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Talk:Diffusion pump

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I seem to recall that cold traps enhance diffusion pump ability, not detract from it. Baffles probably do interfer though. -rmhermen

To be honest, my experience indicates that pumping ability is improved when the cold trap is in use. However, the book I used as a reference for writing this entry, says that cold traps interfere with pumping ability. My guess is that the additional inlet tube length required for the cold trap reduces conductance and thus pumping speed, so pumping speed may be higher without any cold trap. However, if a cold trap is already installed, using it reduces flow of oil into the chamber, resulting in an improvement relative to not using the already installed cold trap. Admittedly, I'm not an expert, so I'd welcome input from anyone with more knowledge on the subject.

--Matt Stoker

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I think the trouble is that diff pumps are really bad at pumping water, which is mostly what you're pumping when you pump from atmosphere. Thus, employing the cold trap seems to improve pumping speed, since it pumps water very well.

--Brian Perkins

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I have a few years of experience with a variety of pumps and traps, and I've found that cold traps can sometimes improve and sometimes hinder pumping efficiency. Here's why:

1) Cold traps place baffles between the pump and chamber, and this reduces conductance to the pump. Use of undersize cold traps can also create a throat that is smaller than the pump, also reducing efficiency. Cold traps are usually not long enough for the length to have an impact. The problem is that in a high vacuum environment, gas molecules have to diffuse into the pump; they're not pushed into it by a pressure gradient. So the molecules have to accidentally find the hole or path leading to the pump in the course of their random walk around the chamber. Smaller holes and larger baffles hinder pumping.

2) Cold traps cryopump the chamber. You wouldn't know that from reading the wikipedia article on cryopumps, but it's true. Vapor molecules, especially water and other outgassing products, will condense out of your chamber and onto the cold trap. In a general-purpose chamber that has not been baked out, your cold trap will typically reduce your pressure by a factor of 100, until it saturates after about 8 hours of operation. In a tighter chamber with bakeout, the cold trap willl not make as much of an improvement, (because the vacuum is already improved to begin with,) but it won't saturate as fast.

In summary, a cold trap acts as a poor man's cryopump in cheap systems, but act as a hairball in ultra-clean systems. Check out the vacuum page for some more discussion.

--Yannick 04:22, 10 Jun 2005 (UTC)

Use of Cold Traps in the process of Vacuum Metallizing
Has anybody had any gain in the use of these pumps in Vacuum Metallizing?? —The preceding unsigned comment was added by 196.209.22.59 (talk) 17:59, 11 December 2006 (UTC).

In my experience typical systems made for metallizing under vacuum use a diff pump. D6stringer 22:38, 9 July 2007 (UTC)

Contradiction
This article currently says that diffusion pumps cannot discharge directly to atmosphere, and also says that a steam ejector is a diffusion pump. These cannot both be right as steam ejectors can and do operate directly to atmosphere.

I would guess a diffusion pump is to an ejector as a turbomolecular pump is to a fan-superficially similar but designed to work at very low pressures where gases behave as free molecules rather than as a continuum.--QuantumEngineer 17:04, 30 June 2007 (UTC)

These are two different application of diffusion pumps. An injector can exhaust to atmosphere, but they can produce a very poor vaccum. If you use them as high-vacuum pumps, they need forepumping. It should be mentioned that mercury diffusion pumps were used for decades. Generally they are somewhat more efficient than oil diffusion pumps, but due to environmental problems they are very rarely used nowadays. (Valdez from Hungary 9 Oct 2007) —Preceding unsigned comment added by 84.0.211.232 (talk) 17:43, 9 October 2007 (UTC)

I suggest to split the article into two parts: oil diffusion pumps (which are a type of high vacuum pumps) and steam/pressurized air ejectors. For the oil diffusion pumps it is true that they cannot exhaust to atmosphere. (Peter.steier 14:43, 21 October 2007 (UTC))

Ok, I did clean up the contradiction myself (I think), Now the articel is mainly on oil diffusion pumps. (Peter.steier 16:31, 21 October 2007 (UTC))

I have browsed around a little more and think now the ejectors are no diffusion pumps and should be removed from this page. They are well covered in Aspirators and work by the Venturi effect observed in the laminar flow regime and not by momentum transfer in molecular flow. I will do this during the following week if no one protests. (Peter.steier 17:05, 21 October 2007 (UTC))

Unfortunate name: function principle has nothing to do with diffusion
I wonder why this kind of pump is named "diffusion", because diffusion does not seem to play a roll in the pumping principle. I remember that when I encountered this kind of pump the first time - as a student some 20 years ago - another student explained me the principle roughly as:

"The oil is heated in the swamp and the entrapped gas diffuses out, and is pumped away by the forepump. The oil condenses on the cold surfaces and the residual gas diffuses into the oil, which flows back to the swamp."

For sure, this explanation is completely wrong, but maybe this is what also the inventor thought in 1913, spawning the strange name? Who has this paper describing the first diffusion pump?

(Peter.steier 16:40, 21 October 2007 (UTC))

 * In low vacuums, pumping creates a pressure gradient that helps push gas towards the inlet of the pump. At high vacuums, a pressure gradient still exists, but the absolute pressures are so low as to have negligeable effect on the movement of the gas. In this regime, gas movement can be better modelled by diffusion. This is the transition from continuum to molecular flow. The practical consequence is that the seal leakage of your pump is now not nearly as important as the throat diameter, because you have to wait for gas molecules to diffuse into the throat, and the pressures are so low that they can be retained by a very fragile seal like an oil curtain. The diffusion pump was the first of these large open-throat devices meant to accept gas by diffusion. After the turbomolecular pump was invented, they were grouped under the umbrella term of momentum transfer pumps, even though they are both diffusion pumps in the old sense.--Yannick 17:11, 21 October 2007 (UTC)

 * Thanx. This should be probably noted in the article. I try it. However, I lack reeferences. (Peter.steier 17:28, 21 October 2007 (UTC))

 * Aw, be bold and put it in. I have references, and I can sprinkle them in when I have the time, or when anyone challenges us. I'm too busy with other articles to do elegant writing on this particular page right now, so your help would be appreciated. Most people are better at putting things into lay terms than I am anyway. By the way, note I made a minor correction to my post above.--Yannick 17:41, 21 October 2007 (UTC)

 * When I was looking for the year of invention and the inventor, I finally found a paper from which Gaede's reasons for using the name "diffusion" are mentioned. (Peter.steier 20:36, 21 October 2007 (UTC))

 * Good work. If we're going to talk about their widespread use, we may want to mention that they are being replaced by turbomolecular pumps in most modern designs. That's original research on my part, but I suspect it would be possible to find a source. Modern turbomoleculars use magnetic bearings, so the diffusion pump's reliability advantage has disappeared. Its only advantage left is low cost, and the savings can easily be wiped out by your first pump stall.--Yannick 03:05, 22 October 2007 (UTC)

 * Old comment, but even in 2011 the oil diffusion pump isn't going anywhere. The turbo pump still cannot compete price and size wise with the diffusion pump. Many large scale industrial vacuum chambers are still diff pumped as they are very low maintenance, low cost and can scale up easily. The largest diff pumps are over a meter in diameter and can pump upward of 50,000 liters a second of air. Turbo pumps top out around 3000-4000 l/s air. Also, magnetic bearings do nothing to make them more reliable. Sudden pressure changes can destroy the fragile blades in a turbo pump causing the lower blades to ingest the upper broken blades leading to a large pile of scrap metal in the pump. If the diff pump oil burns, just pull the pump and clean it out with some solvent. A large diff pump is a few thousand, a large turbo pump is tens of thousands. A diff pump only needs a power source for a heater plate, a turbo pump needs an expensive and elaborate power supply to supply a high frequency AC current to its motor to get the blades spinning upward of 70,000+ RPM. For sensitive lab experiments and equipment, the turbo pump has indeed replaced the diffusion pump. But for large scale systems and even processes where a turbo pump could be damaged by harmful process vapors, the diffusion pump is the first and only choice. 24.186.130.27 (talk) 13:38, 13 June 2011 (UTC)

laminar vs molecular
"Within the nozzles, the flow changes from laminar, to supersonic and molecular."

Shouldn't this be the other way? i.e. "Within the nozzles, the flow changes from molecular, to supersonic and laminar."?

I am not 100% certain, so thats why I rather ask than change. —Preceding unsigned comment added by Davor (talk • contribs) 00:47, 11 June 2008 (UTC)

Pumping speed and baffles
The figure seems to show that pumping speed at low pressures is constant when the pump is baffled, while it drops off with decreasing pressure with no baffle. I am guessing this refers to baffling the input throat of the diffusion pump. I would expect just the opposite. Not an expert here, so I just note it, that it may be unclearly or incorrectly labeled....

 * The figure is adapted from 3.12 in "Building Scientific Apparatus" (ISBN 0813340063). The pumping speed drops as the pressure above the pump approaches the vapor pressure of the pump oil and backstreaming becomes an issue. This is less an issue with a cold trap or baffle. I will try to clarify this point in the article when I get the chance. Thanks for pointing this out. --Kkmurray (talk) 03:46, 12 September 2009 (UTC)

I'm after a section near the beginning along the lines of "Vacuum pumps for Dummies". I am looking for more general information on how vacuum pumps work and what the issues and problems are or were. I have heard about them in my early science days, but after reading the current article I still don't know exactly whats going on.07:00, 15 June 2014 (UTC) — Preceding unsigned comment added by 118.211.175.2 (talk)

title: Talk:Diffusion pump


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Domenico Alberti

Domenico Alberti (c. 1710 – 14 October 1746 (according to other sources: 1740 )) was an Italian singer, harpsichordist, and composer.

Alberti was born in Venice and studied music with Antonio Lotti. He wrote operas, songs, and sonatas for keyboard instruments, for which he is best known today. His sonatas frequently employ arpeggiated accompaniment in the left hand in one of several patterns that are now collectively known as Alberti bass. Alberti was one of the earliest composers to use those patterns, but was not the first or only one. The most well-known of these patterns consists of regular broken chords, with the lowest note sounding first, then the highest, then the middle and then the highest again, with the pattern repeated.

Today, Alberti is regarded as a minor composer, and his works are played or recorded only irregularly. However, the Alberti bass was used by many later composers, and it became an important element in much keyboard music of the classical music era.

An example of Alberti bass (Mozart's Piano Sonata, K 545):

In his own lifetime, Alberti was known as a singer, and often used to accompany himself on the harpsichord. In 1736, he served as a page for Pietro Andrea Cappello, the Venetian ambassador to Spain. While at the Spanish court, the famous castrato singer Farinelli heard him sing. Farinelli was said to have been impressed, although Alberti was an amateur.

Alberti's best known pieces are his keyboard sonatas, although even they are very rarely performed. It is thought he wrote around 36 sonatas, of which 14 have survived. They all have two movements, each in binary form.

It is probable that Mozart's first violin sonatas, written at the age of seven, were modeled on Alberti's work.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Domenico Alberti


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Doris Day

Doris Day (born Doris Mary Anne Kappelhoff; April 3, 1922 – May 13, 2019) was an American actress and singer. She began her career as a big band singer in 1939, achieving commercial success in 1945 with two No. 1 recordings, "Sentimental Journey" and "My Dreams Are Getting Better All the Time" with Les Brown and His Band of Renown. She left Brown to embark on a solo career and recorded more than 650 songs from 1947 to 1967.

Day was one of the leading Hollywood film stars of the 1950s and 1960s. Her film career began with Romance on the High Seas (1948). She starred in films of many genres, including musicals, comedies, dramas and thrillers. She played the title role in Calamity Jane (1953) and starred in Alfred Hitchcock's The Man Who Knew Too Much (1956) with James Stewart. She costarred with Rock Hudson in three successful comedies including Pillow Talk (1959), for which she was nominated for the Academy Award for Best Actress. She also worked with James Garner on both Move Over, Darling (1963) and The Thrill of It All (1963) and starred alongside Clark Gable, Cary Grant, James Cagney, David Niven, Ginger Rogers, Jack Lemmon, Frank Sinatra, Kirk Douglas, Lauren Bacall, and Rod Taylor in various films. After ending her film career in 1968, only briefly removed from the height of her popularity, she starred in her own television sitcom The Doris Day Show (1968–1973).

In 1989, Day was awarded the Golden Globe and the Cecil B. DeMille Award for Lifetime Achievement in Motion Pictures. In 2004, she was awarded the Presidential Medal of Freedom. In 2008, she received the Grammy Lifetime Achievement Award as well as a Legend Award from the Society of Singers. In 2011, she was awarded the Los Angeles Film Critics Association's Career Achievement Award. In 2011, Day released her 29th studio album, My Heart, which contained new material and became a UK Top 10 album. , she was one of eight recording artists to have been the top box-office earner in the United States four times.

Early life
Day was born Doris Mary Anne Kappelhoff on April 3, 1922, in Cincinnati, Ohio, the daughter of German-American parents Alma Sophia (née Welz; 1895–1976) and William Joseph Kappelhoff (1892–1967). She was named after actress Doris Kenyon. Her mother was a homemaker, and her father was a music teacher and choirmaster. Her paternal grandfather Franz Joseph Wilhelm Kappelhoff immigrated to the United States in 1875 and settled within the large German community in Cincinnati. For most of her life, Day stated that she was born in 1924, but on the occasion of her 95th birthday, the Associated Press found her birth certificate that showed a 1922 date of birth.

Day had two older brothers: Richard (1917–1919), who died before her birth, and Paul (1919–1957). Her father's infidelity caused her parents to separate in 1932 when she was 10. She developed an early interest in dance, and in the mid-1930s formed a dance duo with Jerry Doherty that performed in nationwide competitions. On October 13, 1937, while Day was riding with friends, their car collided with a freight train, and she broke her right leg, curtailing her prospects as a professional dancer.

Early career (1938–1947)
While recovering from her car accident, Day sang along with the radio and discovered her singing talent. She later said: "During this long, boring period, I used to while away a lot of time listening to the radio, sometimes singing along with the likes of Benny Goodman, Duke Ellington, Tommy Dorsey, and Glenn Miller. But the one radio voice I listened to above others belonged to Ella Fitzgerald. There was a quality to her voice that fascinated me, and I'd sing along with her, trying to catch the subtle ways she shaded her voice, the casual yet clean way she sang the words."

Day's mother Alma arranged for Doris to receive singing lessons from Grace Raine. After three lessons, Raine told Alma that Day had "tremendous potential" and gave her three lessons per week for the price of one. Years later, Day said that Raine had a greater effect on her singing style and career than had anyone else.

During the eight months when she was receiving singing lessons, Day secured her first professional jobs as a vocalist on the WLW radio program Carlin's Carnival and in a local restaurant, Charlie Yee's Shanghai Inn. During her radio performances, she first caught the attention of Barney Rapp, who was seeking a female vocalist and asked her to audition for the job. According to Rapp, he had auditioned about 200 other singers.

In 1939, Rapp suggested the stage name Doris Day because the Kappelhoff surname was too long for marquees and he admired her rendition of the song "Day After Day". After working with Rapp, Day worked with bandleaders Jimmy James, Bob Crosby and Les Brown. In 1941, Day appeared as a singer in three Soundies with the Les Brown band.

While working with Brown, Day recorded her first hit recording, "Sentimental Journey", released in early 1945. It soon became an anthem for World War II servicemen. The song continues to be associated with Day, and she rerecorded it on several occasions, including a version for her 1971 television special. During 1945–46, Day (as vocalist with the Les Brown Band) had six other top ten hits on the Billboard chart: "My Dreams Are Getting Better All the Time", Tain't Me", "Till the End of Time", "You Won't Be Satisfied (Until You Break My Heart)", "The Whole World Is Singing My Song" and "I Got the Sun in the Mornin. Les Brown said, "As a singer Doris belongs in the company of Bing Crosby and Frank Sinatra."

Early film career (1948–1954)
While singing with the Les Brown band and for nearly two years on Bob Hope's weekly radio program, Day toured extensively across the United States.

Her performance of the song "Embraceable You" impressed songwriter Jule Styne and his partner Sammy Cahn, and they recommended her for a role in Romance on the High Seas (1948). Day was cast for the role after auditioning for director Michael Curtiz. She was shocked to receive the offer and admitted to Curtiz that she was a singer without acting experience. but he appreciated her honesty and felt that "her freckles made her look like the All-American Girl."

The film provided her with a No. 2 hit recording as a soloist, "It's Magic", which occurred two months after her first No. 1 hit "Love Somebody", a duet with Buddy Clark. Day recorded "Someone Like You" before the film My Dream Is Yours (1949), which featured the song. In 1950, she collaborated as a singer with the polka musician Frankie Yankovic, and the U.S. servicemen in Korea voted her their favorite star.

Day continued to appear in light musicals such as On Moonlight Bay (1951), By the Light of the Silvery Moon (1953) and Tea For Two (1950) for Warner Bros. Her most commercially successful film for Warner Bros. was I'll See You in My Dreams (1951), a musical biography of lyricist Gus Kahn that broke box-office records of 20 years. It was Day's fourth film directed by Curtiz. She appeared as the title character in the comedic western-themed musical Calamity Jane (1953). A song from the film, "Secret Love", won the Academy Award for Best Original Song and became Day's fourth No. 1 hit single in the United States.

Between 1950 and 1953, the albums from six of her film musicals charted in the Top 10, including three that reached No. 1. After filming Lucky Me (1954) with Bob Cummings and Young at Heart (1955) with Frank Sinatra, Day elected to not renew her contract with Warner Brothers.

During this period, Day also had her own radio program, The Doris Day Show. It was broadcast on CBS in 1952–1953.

Breakthrough (1955–1958)
Primarily recognized as a musical-comedy actress, Day began to accept more dramatic roles in order to broaden her range. Her dramatic star turn as singer Ruth Etting in Love Me or Leave Me (1955), with top billing above James Cagney, received critical and commercial success, becoming Day's greatest film success to that point. Cagney said that she had "the ability to project the simple, direct statement of a simple, direct idea without cluttering it," comparing her performance to that of Laurette Taylor in the Broadway production The Glass Menagerie (1945). Day felt that it was her best film performance. The film's producer Joe Pasternak said, "I was stunned that Doris did not get an Oscar nomination." The film's soundtrack album became a No. 1 hit.

Day starred in Alfred Hitchcock's suspense film The Man Who Knew Too Much (1956 film) opposite James Stewart. She sang two songs in the film, "Que Sera, Sera (Whatever Will Be, Will Be)", which won an Academy Award for Best Original Song, and "We'll Love Again". The film was Day's 10th to reach the top 10 at the box office. She played the title role in the film noir thriller Julie (1956) with Louis Jourdan.

After three successive dramatic films, Day returned to her musical/comedic roots in The Pajama Game (1957) with John Raitt, based on the Broadway play of the same name. She appeared in the Paramount comedy Teacher's Pet (1958) alongside Clark Gable and Gig Young. She costarred with Richard Widmark and Gig Young in the romantic comedy film The Tunnel of Love (1958) and with Jack Lemmon in It Happened to Jane (1959).

Billboard annual nationwide poll of disc jockeys had ranked Day as the No. 1 female vocalist nine times in ten years (1949 through 1958), but her success and popularity as a singer was now being overshadowed by her box-office appeal.

Box-office success (1959–1968)
In 1959, Day entered her most successful phase as a film actress with a series of romantic comedies beginning with Pillow Talk (1959), costarring Rock Hudson, who became a lifelong friend, and Tony Randall. Day received a nomination for an Academy Award for Best Actress, her only career Oscar nomination. Day, Hudson and Randall appeared in two more films together, Lover Come Back (1961) and Send Me No Flowers (1964).

Along with David Niven and Janis Paige, Day starred in Please Don't Eat the Daisies (1960) and with Cary Grant in the comedy That Touch of Mink (1962). During 1960 and the 1962-1964 period, she ranked No. 1 at the box office, the second woman to be No. 1 four times, an accomplishment equaled by no other actress except Shirley Temple. She set a record that has yet to be matched by receiving seven consecutive Laurel Awards as the top female box-office star.

Day teamed with James Garner starting with The Thrill of It All, followed by Move Over, Darling (both 1963). The film's theme song "Move Over Darling", cowritten by her son, reached No. 8 in the UK. Between these comedic film appearances, Day costarred with Rex Harrison in the thriller Midnight Lace (1960), an update of the stage thriller Gaslight.

Day's next film Do Not Disturb (1965) was popular with audiences, but her popularity soon waned. By the late 1960s, in the period of the emerging sexual revolution, some critics and comics dubbed Day "The World's Oldest Virgin," and she slipped from the list of top box-office stars, last appearing in the top ten with the hit film The Glass Bottom Boat (1966). Among the roles that she declined was that of Mrs. Robinson in The Graduate, a role that eventually went to Anne Bancroft. In her memoirs, Day said that she had rejected the part on moral grounds, finding the script "vulgar and offensive."

Day starred in the Western film The Ballad of Josie in 1967. That same year, Day recorded The Love Album, although it was not released until 1994. In 1968, she starred in the comedy film Where Were You When the Lights Went Out? about the Northeast blackout of November 9, 1965. Her final feature, the comedy With Six You Get Eggroll, was released in 1968.

From 1959 to 1970, Day received nine Laurel Award nominations (and won four times) for best female performance in eight comedies and one drama. From 1959 through 1969, she received six Golden Globe nominations for best female performance in three comedies, one drama (Midnight Lace), one musical (Jumbo) and her television series.

Bankruptcy and television career
After her third husband Martin Melcher died on April 20, 1968, Day was shocked to discover that Melcher and his business partner and advisor Jerome Bernard Rosenthal had squandered her earnings, leaving her deeply in debt. Rosenthal had been her attorney since 1949 when he had represented her in her uncontested divorce action against her second husband, saxophonist George W. Weidler. Day filed suit against Rosenthal in February 1969 and won a successful decision in 1974, but she did not receive compensation until a settlement was reached in 1979.

Day also learned to her displeasure that Melcher had committed her to a television series that became The Doris Day Show.

"It was awful. I was really, really not very well when Marty [Melcher] passed away, and the thought of going into TV was overpowering. But he'd signed me up for a series. And then my son Terry [Melcher] took me walking in Beverly Hills and explained that it wasn't nearly the end of it. I had also been signed up for a bunch of TV specials, all without anyone ever asking me."

Day hated the idea of performing on television but felt obligated to forge ahead with the series. The first episode of The Doris Day Show aired on September 24, 1968, and featured a rerecorded version of "Que Sera, Sera" as its theme song. Day persevered with the show, needing to work to repay her debts, but only after CBS ceded creative control to her and her son. The show enjoyed a successful five-year run, although it may be best remembered for its abrupt season-to-season changes in casting and premise. After the end of the television show's run in 1973, Day largely retired from acting but completed two television specials, The Doris Mary Anne Kappelhoff Special (1971) and Doris Day Today (1975), and she was a guest on various shows in the 1970s.

In the 1985–86 season, Day hosted her own television talk show, Doris Day's Best Friends, on the Christian Broadcasting Network (CBN). The network canceled the show after 26 episodes despite the worldwide publicity that it had received. One episode featured Rock Hudson, who was showing the first public symptoms of AIDS, including severe weight loss and fatigue. He died from the disease later that year. Day later said, "He was very sick. But I just brushed that off and I came out and put my arms around him and said, 'Am I glad to see you'."

1980s and 1990s
In October 1985, the Supreme Court of California rejected Rosenthal's appeal of the multimillion-dollar judgment awarded to Day in her suit against him for legal malpractice and upheld the conclusions of a trial court and an appeals court that Rosenthal had acted improperly. In April 1986, the U.S. Supreme Court refused to review the lower court's judgment. In June 1987, Rosenthal filed a $30 million lawsuit against lawyers whom he claimed had cheated him out of millions of dollars in real-estate investments. He named Day as a codefendant, describing her as an "unwilling, involuntary plaintiff whose consent cannot be obtained." Rosenthal claimed that much of the money that Day had lost was the result of the unwise advice of other attorneys who had suggested that she sell three hotels at a loss, as well as some oil leases in Kentucky and Ohio. He claimed that he had made the investments under a long-term plan and did not intend to sell them until they appreciated in value. Two of the hotels sold in 1970 for about $7 million, and their estimated worth in 1986 was $50 million.

Terry Melcher stated that his father's premature death saved Day from financial ruin. It was not known whether Martin Melcher had himself been duped by Rosenthal, and Day stated publicly that she believed him to be innocent of any deliberate wrongdoing, stating that he "simply trusted the wrong person." Author David Kaufman asserts that Day's former costar Louis Jourdan, maintained that Day disliked her husband, but Day's public statements regarding Melcher appear to contradict that assertion.

Day was scheduled to present, along with Patrick Swayze and Marvin Hamlisch, the award for Best Original Score Oscar at the 61st Academy Awards in March 1989, but she suffered a deep leg cut from a sprinkler and was unable to attend.

Day was inducted into the Ohio Women's Hall of Fame in 1981 and received the Cecil B. DeMille Award for career achievement in 1989. In 1994, Day's Greatest Hits album entered the British charts. Her cover of "Perhaps, Perhaps, Perhaps" was included in the soundtrack of the Australian film Strictly Ballroom.

2000s
Day participated in celebrations of her birthday with an annual Doris Day music marathon.

She declined tribute offers from the American Film Institute and the Kennedy Center Honors because they both require that recipients attend in person. In 2004, she was awarded the Presidential Medal of Freedom by President George W. Bush for her achievements in the entertainment industry and for her work on behalf of animals. President Bush stated:"In the years since, she has kept her fans and shown the breadth of her talent in television and the movies. She starred on screen with leading men from Jimmy Stewart to Ronald Reagan, from Rock Hudson to James Garner. It was a good day for America when Doris Marianne von Kappelhoff (sic) of Evanston, Ohio decided to become an entertainer. It was a good day for our fellow creatures when she gave her good heart to the cause of animal welfare. Doris Day is one of the greats, and America will always love its sweetheart."

Columnist Liz Smith and film critic Rex Reed mounted vigorous campaigns to gather support for an Academy Honorary Award for Day. According to The Hollywood Reporter, the academy had offered her the honorary Oscar multiple times, but she declined as she saw the film industry as a part of her past life. Day received a Grammy for Lifetime Achievement in Music in 2008, albeit again in absentia.

Day received Grammy Hall of Fame Awards in 1998, 1999 and 2012 for her recordings of "Sentimental Journey", "Secret Love" and "Que Sera, Sera", respectively. She was inducted into the Hit Parade Hall of Fame in 2007, and in 2010 received the first Legend Award presented by the Society of Singers.

2010s
At the age of 89, Day released My Heart in the United Kingdom on September 5, 2011, her first new album since the 1994 release of The Love Album, which had been recorded in 1967. The album is a compilation of previously unreleased recordings produced by Day's son Terry Melcher. Tracks include the 1970s Joe Cocker hit "You Are So Beautiful", the Beach Boys' "Disney Girls" and jazz standards such as "My Buddy", which Day originally sang in the film I'll See You in My Dreams (1951).

In the U.S., the album reached No. 12 on Amazon's bestseller list and helped raise funds for the Doris Day Animal League. Day became the oldest artist to score a UK Top 10 with an album featuring new material.

In January 2012, the Los Angeles Film Critics Association presented Day with a Lifetime Achievement Award.

In April 2014, Day made an unexpected public appearance to attend the annual Doris Day Animal Foundation benefit.

Clint Eastwood offered Day a role in a film that he was planning to direct in 2015, but she eventually declined.

Day granted ABC a telephone interview on her birthday in 2016 that was accompanied by photos of her life and career.

Animal-welfare and HIV/AIDS activism
During the filming of The Man Who Knew Too Much, Day observed the mistreatment of animals in a marketplace scene and was inspired to act against animal abuse. She was so appalled at the conditions with which the animals used in filming were kept that she refused to work unless they received sufficient food and proper care. The production company erected feeding stations for the animals and fed them every day before Day would agree to return to work.

In 1971, she cofounded Actors and Others for Animals and appeared in a series of newspaper advertisements denouncing the wearing of fur along with Mary Tyler Moore, Angie Dickinson and Jayne Meadows.

In 1978, Day founded the Doris Day Pet Foundation, now the Doris Day Animal Foundation (DDAF). An independent nonprofit 501(c)(3) grant-giving public charity, DDAF funds other nonprofit causes that promote animal welfare.

To complement the Doris Day Animal Foundation, Day formed the Doris Day Animal League (DDAL) in 1987, a national nonprofit citizens' lobbying organization on behalf of animals. Day actively lobbied the United States Congress in support of legislation designed to safeguard animal welfare on a number of occasions, and in 1995 she originated the annual World Spay Day. The DDAL merged into the Humane Society of the United States (HSUS) in 2006.

The Doris Day Horse Rescue and Adoption Center, which helps abused and neglected horses, opened in 2011 in Murchison, Texas on the grounds of an animal sanctuary started by Day's late friend, author Cleveland Amory. Day contributed $250,000 toward the founding of the center.

A posthumous auction of 1,100 of Day's possessions in April 2020 generated $3 million for the Doris Day Animal Foundation.

Doris Day actively engaged in HIV/AIDS awareness for many years. Her commitment was primarily focused on raising awareness and fundraising for HIV/AIDS research. She co-organized several fundraising events for HIV/AIDS-related charities and provided financial contributions to research and support programs for individuals affected by the disease. In 2011, the Canadian magazine Gay Globe paid tribute to Doris Day by featuring her on the cover of their #79 edition.

Personal life
Day's only child was music producer and songwriter Terry Melcher, who had a hit in the 1960s with "Hey Little Cobra" under the name the Rip Chords before becoming a successful producer whose acts included the Byrds, Paul Revere & the Raiders and the Beach Boys. In the late 1960s, Melcher became acquainted with Charles Manson and nearly signed him to a record deal. In August 1969, the Tate murders, orchestrated by Manson, were committed at the Benedict Canyon house that Melcher had formerly occupied. Melcher died of melanoma in November 2004.

Since the 1980s, Day owned a hotel in Carmel-by-the-Sea called the Cypress Inn, an early pet–friendly hotel that was featured in Architectural Digest in 1999.

Marriages
Day was married four times. From April 1941 to February 1943, she was married to trombonist Al Jorden (1917–1967), whom she met in Barney Rapp's band. Jorden, a violent schizophrenic, committed suicide. When Day became pregnant and refused to have an abortion, he beat her in an attempt to force a miscarriage. Their son was born Terrence Paul Jorden in 1942, and he adopted the surname of Melcher when he was adopted by Day's third husband.

Her second marriage was to George William Weidler (1926–1989), a saxophonist and brother of actress Virginia Weidler, from March 30, 1946, to May 31, 1949. Weidler and Day met again several years later during a brief reconciliation and he introduced her to Christian Science.

Day married American film producer Martin Melcher (1915–1968), who produced many of her films, on April 3, 1951, her 29th birthday, and the marriage lasted until he died in April 1968. Melcher adopted Day's son Terry. As Day and Melcher were both Christian Scientists, she refused to visit a doctor for some time after experiencing symptoms that might have suggested cancer. Following Melcher's death, Day separated from the Church of Christ, Scientist and grew close to charismatic Protestants such as Kathryn Kuhlman, although she never lost interest in Christian Science teaching and practice.

Day's fourth marriage was to Barry Comden (1935–2009) from April 14, 1976, until April 2, 1982. He was the maître d'hôtel at one of Day's favorite restaurants. He knew of her great love of dogs and endeared himself to her by giving her a bag of meat scraps and bones as she left the restaurant. He later complained that Day cared more for her "animal friends" than for him.

Later life
After her retirement from films, Day lived in Carmel-by-the-Sea, California. She had many pets and adopted stray animals. She was a lifelong Republican.

In a rare interview with The Hollywood Reporter on April 4, 2019, the day after her 97th birthday, Day talked about her work on the Doris Day Animal Foundation, founded in 1978. Asked to name the favorite of her films, she answered with Calamity Jane: "I was such a tomboy growing up, and she was such a fun character to play. Of course, the music was wonderful, too—'Secret Love,' especially, is such a beautiful song."

To commemorate her birthday, Day's fans gathered in late March each year for a three-day party in Carmel-by-the-Sea, California. The event was also a fundraiser for her animal foundation. During the 2019 event, there was a special screening of her film Pillow Talk (1959) to celebrate its 60th anniversary. Speaking about the film, Day stated that she "had such fun working with my pal, Rock. We laughed our way through three films we made together and remained great friends. I miss him."

Death
Day died of pneumonia at her home in Carmel Valley, California, on May 13, 2019, at the age of 97. Her death was announced by the Doris Day Animal Foundation. As requested by Day, the foundation announced that there would be no funeral services, grave marker or other public memorials.

Notable films

 * Romance on the High Seas (1948)
 * Calamity Jane (1953)
 * Love Me or Leave Me (1955) (1955)
 * The Man Who Knew Too Much (1956)
 * Pillow Talk (1959)
 * The Thrill of It All (1963)
 * Send Me No Flowers (1964)
 * The Glass Bottom Boat (1966)

Studio albums

 * You're My Thrill (1949)
 * Young Man with a Horn (1950)
 * Tea for Two (1950)
 * Lullaby of Broadway (1951)
 * On Moonlight Bay (1951)
 * I'll See You in My Dreams (1951)
 * By the Light of the Silvery Moon (1953)
 * Calamity Jane (1953)
 * Young at Heart (1954)
 * Love Me or Leave Me (1955)
 * Day Dreams (1955)
 * Day by Day (1956)
 * The Pajama Game (1957)
 * Day by Night (1957)
 * Hooray for Hollywood (1958)
 * Cuttin' Capers (1959)
 * What Every Girl Should Know (1960)
 * Show Time (1960)
 * Listen to Day (1960)
 * Bright and Shiny (1961)
 * I Have Dreamed (1961)
 * Duet (1962)
 * You'll Never Walk Alone (1962)
 *  Billy Rose's Jumbo (1962)
 *  Annie Get Your Gun (1963)
 * Love Him (1963)
 * The Doris Day Christmas Album (1964)
 * With a Smile and a Song (1964)
 * Latin for Lovers (1965)
 * Doris Day's Sentimental Journey (1965)
 * The Love Album (recorded 1967; released in 1994)
 * My Heart (with eight previously unissued tracks recorded in 1985; released in 2011)

Source

title: Doris Day


text:
Distillation

[[File:Simple distillation apparatus.svg|thumb|upright|300px|Laboratory model of a still.

1: The heat source to boil the mixture 2: round-bottom flask containing the mixture to be boiled 3: the head of the still 4: mixture boling-point thermometre 5: the condenser of the still 6: the cooling-water inlet of the condenser 7: the cooling-water outlet of the condenser 8: the distillate-receiving flask 9: vacuum pump and gas inlet 10: the receiver of the still 11: the heat control for heating the mixture 12: stirring mechanism speed control 13: stirring mechanism and heating plate 14: heating bath (oil/sand) for the flask 15: the stirring mechanism (not shown, e.g. boiling chips or mechanical stirring machine) 16: the distillate-cooling water bath. ]]

Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixture and the condensation of the vapors in a still.

Dry distillation (thermolysis and pyrolysis) is the heating of solid materials to produce gases that condense either into fluid products or into solid products. The term dry distillation includes the separation processes of destructive distillation and of chemical cracking, breaking down large hydrocarbon molecules into smaller hydrocarbon molecules. Moreover, a partial distillation results in partial separations of the mixture's components, which process yields nearly-pure components; partial distillation also realizes partial separations of the mixture to increase the concentrations of selected components. In either method, the separation process of distillation exploits the differences in the relative volatility of the component substances of the heated mixture.

In the industrial applications of classical distillation, the term distillation is used as a unit of operation that identifies and denotes a process of physical separation, not a chemical reaction; thus an industrial installation that produces distilled beverages, is a distillery of alcohol. These are some applications of the chemical separation process that is distillation:

 * Distilling fermented products to yield alcoholic beverages with a high content by volume of ethyl alcohol.
 * Desalination to produce potable water and for medico-industrial applications.
 * Crude oil stabilisation, a partial distillation to reduce the vapor pressure of crude oil, which thus is safe to store and to transport, and thereby reduces the volume of atmospheric emissions of volatile hydrocarbons.
 * Fractional distillation used in the midstream operations of an oil refinery for producing fuels and chemical raw materials for livestock feed.
 * Cryogenic Air separation into the component gases — oxygen, nitrogen, and argon — for use as industrial gases.
 * Chemical synthesis to separate impurities and unreacted materials.

Ancient Near East (3000–330 BCE)
Early evidence of distillation was found on Akkadian tablets dated c. 1200 BCE describing perfumery operations. The tablets provided textual evidence that an early, primitive form of distillation was known to the Babylonians of ancient Mesopotamia.

Aristotle
Aristotle knew that water condensing from evaporating seawater is fresh: "I have proved by experiment that salt water evaporated forms fresh, and the vapour does not, when it condenses, condense into sea water again." Letting seawater evaporate and condense into freshwater is not distillation, for distillation involves boiling, but the experiment may have been an important step towards distillation.

Ancient India and China (1–500 CE)
Distillation was practiced in the ancient Indian subcontinent, which is evident from baked clay retorts and receivers found at Taxila, Shaikhan Dheri, and Charsadda in Pakistan and Rang Mahal in India dating to the early centuries of the Common Era. Frank Raymond Allchin says these terracotta distill tubes were "made to imitate bamboo". These "Gandhara stills" were only capable of producing very weak liquor, as there was no efficient means of collecting the vapors at low heat.

Distillation in China may have begun during the Eastern Han dynasty (1st–2nd century CE)

Alexandrian chemists (1–600 CE)
Early evidence of distillation has been found related to alchemists working in Alexandria in Roman Egypt in the 1st century CE.

Desalination by distillation
Distilled water has been in use since at least c. 200 CE, when Alexander of Aphrodisias described the process. Work on distilling other liquids continued in early Byzantine Egypt under Zosimus of Panopolis in the 3rd century.

Islamic Golden Age
Medieval Muslim chemists such as Jābir ibn Ḥayyān (Latin: Geber, ninth century) and Abū Bakr al-Rāzī (Latin: Rhazes, c. 865–925) experimented extensively with the distillation of various substances.

Alcohol distillation
The distillation of wine is attested in Arabic works attributed to al-Kindī (c. 801–873 CE) and to al-Fārābī (c. 872–950), and in the 28th book of al-Zahrāwī's (Latin: Abulcasis, 936–1013) Kitāb al-Taṣrīf (later translated into Latin as Liber servatoris). In the twelfth century, recipes for the production of aqua ardens ("burning water", i.e., ethanol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists. The works of Taddeo Alderotti (1223–1296) describe a method for concentrating alcohol involving repeated distillation through a water-cooled still, by which an alcohol purity of 90% could be obtained.

Fractional distillation
The fractional distillation of organic substances plays an important role in the works attributed to Jābir, such as in the Seventy Books ('The Book of Seventy'), translated into Latin by Gerard of Cremona (c. 1114–1187) under the title Liber de septuaginta. The Jabirian experiments with fractional distillation of animal and vegetable substances, and to a lesser degree also of mineral substances, is the main topic of the De anima in arte alkimiae, an originally Arabic work falsely attributed to Avicenna that was translated into Latin and would go on to form the most important alchemical source for Roger Bacon (c. 1220–1292).

Alcohol distillation
The distillation of beverages began in the Southern Song (10th–13th century) and Jin (12th–13th century) dynasties, according to archaeological evidence. A still was found in an archaeological site in Qinglong, Hebei province, China, dating back to the 12th century. Distilled beverages were common during the Yuan dynasty (13th–14th century).

Modern era
In 1500, German alchemist Hieronymus Brunschwig published Liber de arte distillandi de simplicibus (The Book of the Art of Distillation out of Simple Ingredients), the first book solely dedicated to the subject of distillation, followed in 1512 by a much expanded version. In 1651, John French published The Art of Distillation, the first major English compendium on the practice, but it has been claimed that much of it derives from Braunschweig's work. This includes diagrams with people in them showing the industrial rather than bench scale of the operation.

As alchemy evolved into the science of chemistry, vessels called retorts became used for distillations. Both alembics and retorts are forms of glassware with long necks pointing to the side at a downward angle to act as air-cooled condensers to condense the distillate and let it drip downward for collection. Later, copper alembics were invented. Riveted joints were often kept tight by using various mixtures, for instance a dough made of rye flour. These alembics often featured a cooling system around the beak, using cold water, for instance, which made the condensation of alcohol more efficient. These were called pot stills. Today, the retorts and pot stills have been largely supplanted by more efficient distillation methods in most industrial processes. However, the pot still is still widely used for the elaboration of some fine alcohols, such as cognac, Scotch whisky, Irish whiskey, tequila, rum, cachaça, and some vodkas. Pot stills made of various materials (wood, clay, stainless steel) are also used by bootleggers in various countries. Small pot stills are also sold for use in the domestic production of flower water or essential oils.

Early forms of distillation involved batch processes using one vaporization and one condensation. Purity was improved by further distillation of the condensate. Greater volumes were processed by simply repeating the distillation. Chemists reportedly carried out as many as 500 to 600 distillations in order to obtain a pure compound.

In the early 19th century, the basics of modern techniques, including pre-heating and reflux, were developed. In 1822, Anthony Perrier developed one of the first continuous stills, and then, in 1826, Robert Stein improved that design to make his patent still. In 1830, Aeneas Coffey got a patent for improving the design even further. Coffey's continuous still may be regarded as the archetype of modern petrochemical units. The French engineer Armand Savalle developed his steam regulator around 1846. In 1877, Ernest Solvay was granted a U.S. Patent for a tray column for ammonia distillation, and the same and subsequent years saw developments in this theme for oils and spirits.

With the emergence of chemical engineering as a discipline at the end of the 19th century, scientific rather than empirical methods could be applied. The developing petroleum industry in the early 20th century provided the impetus for the development of accurate design methods, such as the McCabe–Thiele method by Ernest Thiele and the Fenske equation. The first industrial plant in the United States to use distillation as a means of ocean desalination opened in Freeport, Texas in 1961 with the hope of bringing water security to the region. The availability of powerful computers has allowed direct computer simulations of distillation columns.

Applications
The application of distillation can roughly be divided into four groups: laboratory scale, industrial distillation, distillation of herbs for perfumery and medicinals (herbal distillate), and food processing. The latter two are distinctively different from the former two in that distillation is not used as a true purification method but more to transfer all volatiles from the source materials to the distillate in the processing of beverages and herbs.

The main difference between laboratory scale distillation and industrial distillation are that laboratory scale distillation is often performed on a batch basis, whereas industrial distillation often occurs continuously. In batch distillation, the composition of the source material, the vapors of the distilling compounds, and the distillate change during the distillation. In batch distillation, a still is charged (supplied) with a batch of feed mixture, which is then separated into its component fractions, which are collected sequentially from most volatile to less volatile, with the bottoms – remaining least or non-volatile fraction – removed at the end. The still can then be recharged and the process repeated.

In continuous distillation, the source materials, vapors, and distillate are kept at a constant composition by carefully replenishing the source material and removing fractions from both vapor and liquid in the system. This results in a more detailed control of the separation process.

Idealized model
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the pressure around the liquid, enabling bubbles to form without being crushed. A special case is the normal boiling point, where the vapor pressure of the liquid equals the ambient atmospheric pressure.

It is a misconception that in a liquid mixture at a given pressure, each component boils at the boiling point corresponding to the given pressure, allowing the vapors of each component to collect separately and purely. However, this does not occur, even in an idealized system. Idealized models of distillation are essentially governed by Raoult's law and Dalton's law and assume that vapor–liquid equilibria are attained.

Raoult's law states that the vapor pressure of a solution is dependent on 1) the vapor pressure of each chemical component in the solution and 2) the fraction of solution each component makes up, a.k.a. the mole fraction. This law applies to ideal solutions, or solutions that have different components but whose molecular interactions are the same as or very similar to pure solutions.

Dalton's law states that the total pressure is the sum of the partial pressures of each individual component in the mixture. When a multi-component liquid is heated, the vapor pressure of each component will rise, thus causing the total vapor pressure to rise. When the total vapor pressure reaches the pressure surrounding the liquid, boiling occurs and liquid turns to gas throughout the bulk of the liquid. A mixture with a given composition has one boiling point at a given pressure when the components are mutually soluble. A mixture of constant composition does not have multiple boiling points.

An implication of one boiling point is that lighter components never cleanly "boil first". At boiling point, all volatile components boil, but for a component, its percentage in the vapor is the same as its percentage of the total vapor pressure. Lighter components have a higher partial pressure and, thus, are concentrated in the vapor, but heavier volatile components also have a (smaller) partial pressure and necessarily vaporize also, albeit at a lower concentration in the vapor. Indeed, batch distillation and fractionation succeed by varying the composition of the mixture. In batch distillation, the batch vaporizes, which changes its composition; in fractionation, liquid higher in the fractionation column contains more lights and boils at lower temperatures. Therefore, starting from a given mixture, it appears to have a boiling range instead of a boiling point, although this is because its composition changes: each intermediate mixture has its own, singular boiling point.

The idealized model is accurate in the case of chemically similar liquids, such as benzene and toluene. In other cases, severe deviations from Raoult's law and Dalton's law are observed, most famously in the mixture of ethanol and water. These compounds, when heated together, form an azeotrope, which is when the vapor phase and liquid phase contain the same composition. Although there are computational methods that can be used to estimate the behavior of a mixture of arbitrary components, the only way to obtain accurate vapor–liquid equilibrium data is by measurement.

It is not possible to completely purify a mixture of components by distillation, as this would require each component in the mixture to have a zero partial pressure. If ultra-pure products are the goal, then further chemical separation must be applied. When a binary mixture is vaporized and the other component, e.g., a salt, has zero partial pressure for practical purposes, the process is simpler.

Batch or differential distillation
Heating an ideal mixture of two volatile substances, A and B, with A having the higher volatility, or lower boiling point, in a batch distillation setup (such as in an apparatus depicted in the opening figure) until the mixture is boiling results in a vapor above the liquid that contains a mixture of A and B. The ratio between A and B in the vapor will be different from the ratio in the liquid. The ratio in the liquid will be determined by how the original mixture was prepared, while the ratio in the vapor will be enriched in the more volatile compound, A (due to Raoult's Law, see above). The vapor goes through the condenser and is removed from the system. This, in turn, means that the ratio of compounds in the remaining liquid is now different from the initial ratio (i.e., more enriched in B than in the starting liquid).

The result is that the ratio in the liquid mixture is changing, becoming richer in component B. This causes the boiling point of the mixture to rise, which results in a rise in the temperature in the vapor, which results in a changing ratio of A : B in the gas phase (as distillation continues, there is an increasing proportion of B in the gas phase). This results in a slowly changing ratio of A : B in the distillate.

If the difference in vapour pressure between the two components A and B is large – generally expressed as the difference in boiling points – the mixture in the beginning of the distillation is highly enriched in component A, and when component A has distilled off, the boiling liquid is enriched in component B.

Continuous distillation
Continuous distillation is an ongoing distillation in which a liquid mixture is continuously (without interruption) fed into the process and separated fractions are removed continuously as output streams occur over time during the operation. Continuous distillation produces a minimum of two output fractions, including at least one volatile distillate fraction, which has boiled and been separately captured as a vapor and then condensed to a liquid. There is always a bottoms (or residue) fraction, which is the least volatile residue that has not been separately captured as a condensed vapor.

Continuous distillation differs from batch distillation in the respect that concentrations should not change over time. Continuous distillation can be run at a steady state for an arbitrary amount of time. For any source material of specific composition, the main variables that affect the purity of products in continuous distillation are the reflux ratio and the number of theoretical equilibrium stages, in practice determined by the number of trays or the height of packing. Reflux is a flow from the condenser back to the column, which generates a recycle that allows a better separation with a given number of trays. Equilibrium stages are ideal steps where compositions achieve vapor–liquid equilibrium, repeating the separation process and allowing better separation given a reflux ratio. A column with a high reflux ratio may have fewer stages, but it refluxes a large amount of liquid, giving a wide column with a large holdup. Conversely, a column with a low reflux ratio must have a large number of stages, thus requiring a taller column.

General improvements
Both batch and continuous distillations can be improved by making use of a fractionating column on top of the distillation flask. The column improves separation by providing a larger surface area for the vapor and condensate to come into contact. This helps it remain at equilibrium for as long as possible. The column can even consist of small subsystems ('trays' or 'dishes') which all contain an enriched, boiling liquid mixture, all with their own vapor–liquid equilibrium.

There are differences between laboratory-scale and industrial-scale fractionating columns, but the principles are the same. Examples of laboratory-scale fractionating columns (in increasing efficiency) include:
 * Air condenser
 * Vigreux column (usually laboratory scale only)
 * Packed column (packed with glass beads, metal pieces, or other chemically inert material)
 * Spinning band distillation system.

Laboratory procedures
Laboratory scale distillations are almost exclusively run as batch distillations. The device used in distillation, sometimes referred to as a still, consists at a minimum of a reboiler or pot in which the source material is heated, a condenser in which the heated vapor is cooled back to the liquid state, and a receiver in which the concentrated or purified liquid, called the distillate, is collected. Several laboratory scale techniques for distillation exist (see also distillation types).

A completely sealed distillation apparatus could experience extreme and rapidly varying internal pressure, which could cause it to burst open at the joints. Therefore, some path is usually left open (for instance, at the receiving flask) to allow the internal pressure to equalize with atmospheric pressure. Alternatively, a vacuum pump may be used to keep the apparatus at a lower than atmospheric pressure. If the substances involved are air- or moisture-sensitive, the connection to the atmosphere can be made through one or more drying tubes packed with materials that scavenge the undesired air components, or through bubblers that provide a movable liquid barrier. Finally, the entry of undesired air components can be prevented by pumping a low but steady flow of suitable inert gas, like nitrogen, into the apparatus.

Simple distillation
In simple distillation, the vapor is immediately channeled into a condenser. Consequently, the distillate is not pure but rather its composition is identical to the composition of the vapors at the given temperature and pressure. That concentration follows Raoult's law.

As a result, simple distillation is effective only when the liquid boiling points differ greatly (rule of thumb is 25 °C) or when separating liquids from non-volatile solids or oils. For these cases, the vapor pressures of the components are usually different enough that the distillate may be sufficiently pure for its intended purpose.

A cutaway schematic of a simple distillation operation is shown at right. The starting liquid 15 in the boiling flask 2 is heated by a combined hotplate and magnetic stirrer 13 via a silicone oil bath (orange, 14). The vapor flows through a short Vigreux column 3, then through a Liebig condenser 5, is cooled by water (blue) that circulates through ports 6 and 7. The condensed liquid drips into the receiving flask 8, sitting in a cooling bath (blue, 16). The adapter 10 has a connection 9 that may be fitted to a vacuum pump. The components are connected by ground glass joints.

Fractional distillation
For many cases, the boiling points of the components in the mixture will be sufficiently close that Raoult's law must be taken into consideration. Therefore, fractional distillation must be used to separate the components by repeated vaporization-condensation cycles within a packed fractionating column. This separation, by successive distillations, is also referred to as rectification.

As the solution to be purified is heated, its vapors rise to the fractionating column. As it rises, it cools, condensing on the condenser walls and the surfaces of the packing material. Here, the condensate continues to be heated by the rising hot vapors; it vaporizes once more. However, the composition of the fresh vapors is determined once again by Raoult's law. Each vaporization-condensation cycle (called a theoretical plate) will yield a purer solution of the more volatile component. In reality, each cycle at a given temperature does not occur at exactly the same position in the fractionating column; theoretical plate is thus a concept rather than an accurate description.

More theoretical plates lead to better separations. A spinning band distillation system uses a spinning band of Teflon or metal to force the rising vapors into close contact with the descending condensate, increasing the number of theoretical plates.

Steam distillation
Like vacuum distillation, steam distillation is a method for distilling compounds which are heat-sensitive. The temperature of the steam is easier to control than the surface of a heating element and allows a high rate of heat transfer without heating at a very high temperature. This process involves bubbling steam through a heated mixture of the raw material. By Raoult's law, some of the target compound will vaporize (in accordance with its partial pressure). The vapor mixture is cooled and condensed, usually yielding a layer of oil and a layer of water.

Steam distillation of various aromatic herbs and flowers can result in two products: an essential oil as well as a watery herbal distillate. The essential oils are often used in perfumery and aromatherapy while the watery distillates have many applications in aromatherapy, food processing and skin care.

Vacuum distillation
Some compounds have very high boiling points. To boil such compounds, it is often better to lower the pressure at which such compounds are boiled instead of increasing the temperature. Once the pressure is lowered to the vapor pressure of the compound (at the given temperature), boiling and the rest of the distillation process can commence. This technique is referred to as vacuum distillation and it is commonly found in the laboratory in the form of the rotary evaporator.

This technique is also very useful for compounds which boil beyond their decomposition temperature at atmospheric pressure and which would therefore be decomposed by any attempt to boil them under atmospheric pressure.

Molecular distillation
Molecular distillation is vacuum distillation below the pressure of 0.01 torr. 0.01 torr is one order of magnitude above high vacuum, where fluids are in the free molecular flow regime, i.e., the mean free path of molecules is comparable to the size of the equipment. The gaseous phase no longer exerts significant pressure on the substance to be evaporated, and consequently, rate of evaporation no longer depends on pressure. That is, because the continuum assumptions of fluid dynamics no longer apply, mass transport is governed by molecular dynamics rather than fluid dynamics. Thus, a short path between the hot surface and the cold surface is necessary, typically by suspending a hot plate covered with a film of feed next to a cold plate with a line of sight in between. Molecular distillation is used industrially for purification of oils.

Short path distillation
Short path distillation is a distillation technique that involves the distillate travelling a short distance, often only a few centimeters, and is normally done at reduced pressure. A classic example would be a distillation involving the distillate travelling from one glass bulb to another, without the need for a condenser separating the two chambers. This technique is often used for compounds which are unstable at high temperatures or to purify small amounts of compound. The advantage is that the heating temperature can be considerably lower (at reduced pressure) than the boiling point of the liquid at standard pressure, and the distillate only has to travel a short distance before condensing. A short path ensures that little compound is lost on the sides of the apparatus. The Kugelrohr apparatus is a kind of short path distillation method which often contains multiple chambers to collect distillate fractions.

Air-sensitive vacuum distillation
Some compounds have high boiling points as well as being air sensitive. A simple vacuum distillation system as exemplified above can be used, whereby the vacuum is replaced with an inert gas after the distillation is complete. However, this is a less satisfactory system if one desires to collect fractions under a reduced pressure. To do this a "cow" or "pig" adaptor can be added to the end of the condenser, or for better results or for very air sensitive compounds a Perkin triangle apparatus can be used.

The Perkin triangle has means via a series of glass or Teflon taps to allows fractions to be isolated from the rest of the still, without the main body of the distillation being removed from either the vacuum or heat source, and thus can remain in a state of reflux. To do this, the sample is first isolated from the vacuum by means of the taps, the vacuum over the sample is then replaced with an inert gas (such as nitrogen or argon) and can then be stoppered and removed. A fresh collection vessel can then be added to the system, evacuated and linked back into the distillation system via the taps to collect a second fraction, and so on, until all fractions have been collected.

Zone distillation
Zone distillation is a distillation process in a long container with partial melting of refined matter in moving liquid zone and condensation of vapor in the solid phase at condensate pulling in cold area. The process is worked in theory. When zone heater is moving from the top to the bottom of the container then solid condensate with irregular impurity distribution is forming. Then most pure part of the condensate may be extracted as product. The process may be iterated many times by moving (without turnover) the received condensate to the bottom part of the container on the place of refined matter. The irregular impurity distribution in the condensate (that is efficiency of purification) increases with the number of iterations. Zone distillation is the distillation analog of zone recrystallization. Impurity distribution in the condensate is described by known equations of zone recrystallization – with the replacement of the distribution co-efficient k of crystallization - for the separation factor α of distillation.

Closed-system vacuum distillation (cryovap)
Non-condensable gas can be expelled from the apparatus by the vapor of relatively volatile co-solvent, which spontaneously evaporates during initial pumping, and this can be achieved with regular oil or diaphragm pump.

Other types

 * The process of reactive distillation involves using the reaction vessel as the still. In this process, the product is usually significantly lower boiling than its reactants. As the product is formed from the reactants, it is vaporized and removed from the reaction mixture. This technique is an example of a continuous vs. a batch process; advantages include less downtime to charge the reaction vessel with starting material, and less workup. Distillation "over a reactant" could be classified as a reactive distillation. It is typically used to remove volatile impurity from the distillation feed. For example, a little lime may be added to remove carbon dioxide from water followed by a second distillation with a little sulfuric acid added to remove traces of ammonia.
 * Catalytic distillation is the process by which the reactants are catalyzed while being distilled to continuously separate the products from the reactants. This method is used to assist equilibrium reactions in reaching completion.
 * Pervaporation is a method for the separation of mixtures of liquids by partial vaporization through a non-porous membrane.
 * Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture.
 * Flash evaporation (or partial evaporation) is the partial vaporization that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations, being equivalent to a distillation with only one equilibrium stage.
 * Codistillation is distillation which is performed on mixtures in which the two compounds are not miscible. In the laboratory, the Dean-Stark apparatus is used for this purpose to remove water from synthesis products. The Bleidner apparatus is another example with two refluxing solvents.
 * Membrane distillation is a type of distillation in which vapors of a mixture to be separated are passed through a membrane, which selectively permeates one component of mixture. Vapor pressure difference is the driving force. It has potential applications in seawater desalination and in removal of organic and inorganic components.

The unit process of evaporation may also be called "distillation":
 * In rotary evaporation a vacuum distillation apparatus is used to remove bulk solvents from a sample. Typically the vacuum is generated by a water aspirator or a membrane pump.
 * In a Kugelrohr apparatus a short path distillation apparatus is typically used (generally in combination with a (high) vacuum) to distill high boiling (> 300 °C) compounds. The apparatus consists of an oven in which the compound to be distilled is placed, a receiving portion which is outside of the oven, and a means of rotating the sample. The vacuum is normally generated by using a high vacuum pump.

Other uses:
 * Dry distillation or destructive distillation, despite the name, is not truly distillation, but rather a chemical reaction known as pyrolysis in which solid substances are heated in an inert or reducing atmosphere and any volatile fractions, containing high-boiling liquids and products of pyrolysis, are collected. The destructive distillation of wood to give methanol is the root of its common name – wood alcohol.
 * Freeze distillation is an analogous method of purification using freezing instead of evaporation. It is not truly distillation, but a recrystallization where the product is the mother liquor, and does not produce products equivalent to distillation. This process is used in the production of ice beer and ice wine to increase ethanol and sugar content, respectively. It is also used to produce applejack. Unlike distillation, freeze distillation concentrates poisonous congeners rather than removing them; As a result, many countries prohibit such applejack as a health measure. Also, distillation by evaporation can separate these since they have different boiling points.
 * Distillation by filtration: In early alchemy and chemistry, otherwise known as natural philosophy, a form of "distillation" by capillary filtration was known as a form of distillation at the time. In this, a series of cups or bowls were set upon a stepped support with a "wick" of cotton or felt-like material, which had been wetted with water or a clear liquid with each step dripping down through the wetted cloth through capillary action in succeeding steps, creating a "purification" of the liquid, leaving solid materials behind in the upper bowls and purifying the succeeding product through capillary action through the moistened cloth. This was called "distillatio" by filtration by those using the method.

Azeotropic process
Interactions between the components of the solution create properties unique to the solution, as most processes entail non-ideal mixtures, where Raoult's law does not hold. Such interactions can result in a constant-boiling azeotrope which behaves as if it were a pure compound (i.e., boils at a single temperature instead of a range). At an azeotrope, the solution contains the given component in the same proportion as the vapor, so that evaporation does not change the purity, and distillation does not result in separation. For example, 95.6% ethanol (by mass) in water forms an azeotrope at 78.1 °C.

If the azeotrope is not considered sufficiently pure for use, there exist some techniques to break the azeotrope to give a more pure distillate. These techniques are known as azeotropic distillation. Some techniques achieve this by "jumping" over the azeotropic composition (by adding another component to create a new azeotrope, or by varying the pressure). Others work by chemically or physically removing or sequestering the impurity. For example, to purify ethanol beyond 95%, a drying agent (or desiccant, such as potassium carbonate) can be added to convert the soluble water into insoluble water of crystallization. Molecular sieves are often used for this purpose as well.

Immiscible liquids, such as water and toluene, easily form azeotropes. Commonly, these azeotropes are referred to as a low boiling azeotrope because the boiling point of the azeotrope is lower than the boiling point of either pure component. The temperature and composition of the azeotrope is easily predicted from the vapor pressure of the pure components, without use of Raoult's law. The azeotrope is easily broken in a distillation set-up by using a liquid–liquid separator (a decanter) to separate the two liquid layers that are condensed overhead. Only one of the two liquid layers is refluxed to the distillation set-up.

High boiling azeotropes, such as a 20 percent by weight mixture of hydrochloric acid in water, also exist. As implied by the name, the boiling point of the azeotrope is greater than the boiling point of either pure component.

Breaking an azeotrope with unidirectional pressure manipulation
The boiling points of components in an azeotrope overlap to form a band. By exposing an azeotrope to a vacuum or positive pressure, it is possible to bias the boiling point of one component away from the other by exploiting the differing vapor pressure curves of each; the curves may overlap at the azeotropic point, but are unlikely to remain identical further along the pressure axis to either side of the azeotropic point. When the bias is great enough, the two boiling points no longer overlap and so the azeotropic band disappears.

This method can remove the need to add other chemicals to a distillation, but it has two potential drawbacks.

Under negative pressure, power for a vacuum source is needed and the reduced boiling points of the distillates requires that the condenser be run cooler to prevent distillate vapors being lost to the vacuum source. Increased cooling demands will often require additional energy and possibly new equipment or a change of coolant.

Alternatively, if positive pressures are required, standard glassware can not be used, energy must be used for pressurization and there is a higher chance of side reactions occurring in the distillation, such as decomposition, due to the higher temperatures required to effect boiling.

A unidirectional distillation will rely on a pressure change in one direction, either positive or negative.

Pressure-swing distillation
Pressure-swing distillation is essentially the same as the unidirectional distillation used to break azeotropic mixtures, but here both positive and negative pressures may be employed.

This improves the selectivity of the distillation and allows a chemist to optimize distillation by avoiding extremes of pressure and temperature that waste energy. This is particularly important in commercial applications.

One example of the application of pressure-swing distillation is during the industrial purification of ethyl acetate after its catalytic synthesis from ethanol.

Industrial process

Large scale industrial distillation applications include both batch and continuous fractional, vacuum, azeotropic, extractive, and steam distillation. The most widely used industrial applications of continuous, steady-state fractional distillation are in petroleum refineries, petrochemical and chemical plants and natural gas processing plants.

To control and optimize such industrial distillation, a standardized laboratory method, ASTM D86, is established. This test method extends to the atmospheric distillation of petroleum products using a laboratory batch distillation unit to quantitatively determine the boiling range characteristics of petroleum products.

Industrial distillation is typically performed in large, vertical cylindrical columns known as distillation towers or distillation columns with diameters ranging from about 0.65 to 16 m and heights ranging from about 6 to 90 m or more. When the process feed has a diverse composition, as in distilling crude oil, liquid outlets at intervals up the column allow for the withdrawal of different fractions or products having different boiling points or boiling ranges. The "lightest" products (those with the lowest boiling point) exit from the top of the columns and the "heaviest" products (those with the highest boiling point) exit from the bottom of the column and are often called the bottoms.

Industrial towers use reflux to achieve a more complete separation of products. Reflux refers to the portion of the condensed overhead liquid product from a distillation or fractionation tower that is returned to the upper part of the tower as shown in the schematic diagram of a typical, large-scale industrial distillation tower. Inside the tower, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficiency of the distillation tower. The more reflux that is provided for a given number of theoretical plates, the better the tower's separation of lower boiling materials from higher boiling materials. Alternatively, the more reflux that is provided for a given desired separation, the fewer the number of theoretical plates required. Chemical engineers must choose what combination of reflux rate and number of plates is both economically and physically feasible for the products purified in the distillation column.

Such industrial fractionating towers are also used in cryogenic air separation, producing liquid oxygen, liquid nitrogen, and high purity argon. Distillation of chlorosilanes also enables the production of high-purity silicon for use as a semiconductor.

Design and operation of a distillation tower depends on the feed and desired products. Given a simple, binary component feed, analytical methods such as the McCabe–Thiele method or the Fenske equation can be used. For a multi-component feed, simulation models are used both for design and operation. Moreover, the efficiencies of the vapor–liquid contact devices (referred to as "plates" or "trays") used in distillation towers are typically lower than that of a theoretical 100% efficient equilibrium stage. Hence, a distillation tower needs more trays than the number of theoretical vapor–liquid equilibrium stages. A variety of models have been postulated to estimate tray efficiencies.

In modern industrial uses, a packing material is used in the column instead of trays when low pressure drops across the column are required. Other factors that favor packing are: vacuum systems, smaller diameter columns, corrosive systems, systems prone to foaming, systems requiring low liquid holdup, and batch distillation. Conversely, factors that favor plate columns are: presence of solids in feed, high liquid rates, large column diameters, complex columns, columns with wide feed composition variation, columns with a chemical reaction, absorption columns, columns limited by foundation weight tolerance, low liquid rate, large turn-down ratio and those processes subject to process surges. This packing material can either be random or dumped packing (1 - 3 in wide) such as Raschig rings or structured sheet metal. Liquids tend to wet the surface of the packing and the vapors pass across this wetted surface, where mass transfer takes place. Unlike conventional tray distillation in which every tray represents a separate point of vapor–liquid equilibrium, the vapor–liquid equilibrium curve in a packed column is continuous. However, when modeling packed columns, it is useful to compute a number of "theoretical stages" to denote the separation efficiency of the packed column with respect to more traditional trays. Differently shaped packings have different surface areas and void space between packings. Both these factors affect packing performance.

Another factor in addition to the packing shape and surface area that affects the performance of random or structured packing is the liquid and vapor distribution entering the packed bed. The number of theoretical stages required to make a given separation is calculated using a specific vapor to liquid ratio. If the liquid and vapor are not evenly distributed across the superficial tower area as it enters the packed bed, the liquid to vapor ratio will not be correct in the packed bed and the required separation will not be achieved. The packing will appear to not be working properly. The height equivalent to a theoretical plate (HETP) will be greater than expected. The problem is not the packing itself but the mal-distribution of the fluids entering the packed bed. Liquid mal-distribution is more frequently the problem than vapor. The design of the liquid distributors used to introduce the feed and reflux to a packed bed is critical to making the packing perform to it maximum efficiency. Methods of evaluating the effectiveness of a liquid distributor to evenly distribute the liquid entering a packed bed can be found in references. Considerable work has been done on this topic by Fractionation Research, Inc. (commonly known as FRI).

Multi-effect distillation
The goal of multi-effect distillation is to increase the energy efficiency of the process, for use in desalination, or in some cases one stage in the production of ultrapure water. The number of effects is inversely proportional to the kW·h/m3 of water recovered figure and refers to the volume of water recovered per unit of energy compared with single-effect distillation. One effect is roughly 636 kW·h/m3:
 * Multi-stage flash distillation can achieve more than 20 effects with thermal energy input, as mentioned in the article.
 * Vapor compression evaporation – Commercial large-scale units can achieve around 72 effects with electrical energy input, according to manufacturers.

There are many other types of multi-effect distillation processes, including one referred to as simply multi-effect distillation (MED), in which multiple chambers, with intervening heat exchangers, are employed.

Beverages
Carbohydrate-containing plant materials are allowed to ferment, producing a dilute solution of ethanol in the process. Spirits such as whiskey and rum are prepared by distilling these dilute solutions of ethanol. Components other than ethanol, including water, esters, and other alcohols, are collected in the condensate, which account for the flavor of the beverage. Some of these beverages are then stored in barrels or other containers to acquire more flavor compounds and characteristic flavors.

title: Distillation