US4076576A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for the evaporation of liquids
Assignee: Ahlstrom Corp
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Filing: 1975-12-29
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Granted: 1978-02-28
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Expires: 1995-12-29
Abstract
Abstract Liquids which, when dilute, tend to froth during mixing or boiling are evaporated in an evaporator by feeding the entire liquid quantity to be evaporated into the evaporator, bringing only part of it in indirect heat exchange contact with a hot medium to concentrate the liquid, recycling part of the concentrated liquid to the heat exchange to prevent frothing of the liquid to be evaporated, and withdrawing the vaporized portion and the concentrated liquid from the evaporator.
Inventors
- 👤 Lauri Tapani Marttala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:27
CPC Classifications
B; B01; B01D; B01D1/00; B01D1/22; B01D1/26; D; D21; D21C; D21C11/00; D21C11/10
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
188 words
An apparatus for evaporating liquids which, when dilute, tend to froth during mixing or boiling, the apparatus having an evaporation chamber and in the chamber: a heat exchanger and means for causing the liquid to be evaporated to flow along the heat exchange surfaces of the heat exchanger in order to boil and concentrate the liquid, a feed inlet for feeding into the chamber the liquid to be evaporated, an outlet, in the lower part of the chamber, for removing the concentrated liquid, and an outlet, in the upper part, for removing the vapor from the chamber; and means for recirculating onto the heat exchange surfaces of the heat exchanger the concentrated liquid from the heat exchanger accumulated in the lower part of the chamber, and a member which divides the lower part of the evaporation chamber into two liquid compartments having a joint vapor space, said means for recirculating the concentrated liquid having the inlet connected to the first liquid compartment and to the feed inlet for the liquid to be expansion evaporated and the outlet for concentrated liquid having been connected to the second liquid compartment.
Claim 2
Independent Claim
188 words
An apparatus for evaporating liquids which, when dilute, tend to froth during mixing or boiling, the apparatus having an evaporation chamber and in the chamber: a heat exchanger and means for causing the liquid to be evaporated to flow along the heat exchange surfaces of the heat exchanger in order to boil and concentrate the liquid, a feed inlet for feeding into the chamber the liquid to be evaporated, an outlet, in the lower part of the chamber, for removing the concentrated liquid, and an outlet, in the upper part, for removing the vapor from the chamber; and means for recirculating onto the heat exchange surfaces of the heat exchanger the concentrated liquid from the heat exchanger accumulated in the lower part of the chamber, and a member which divides the lower part of the evaporation chamber into two liquid compartments having a joint vapor space, said means for recirculating the concentrated liquid having the inlet connected to the first liquid compartment and to the feed inlet for the liquid to be expansion evaporated and the outlet for concentrated liquid having been connected to the second liquid compartment.
Claim 3
Dependent Claim
57 words
An apparatus according to claim 1, comprising a distribution device which is located above the heat exchanger and connected to the outlet of the recirculating means in order to cause the liquid to flow onto the heat exchange surfaces of the heat exchanger, the heat exchanger being supported above the liquid at the bottom of the chamber.
Claim 4
Dependent Claim
37 words
An apparatus according to claim 1, comprising a control device connected to said recirculating means in order to control the amount of the liquid to be added to the portion concentrated by heat exchange prior to recycling.
Claim 5
Dependent Claim
59 words
An apparatus according to claim 1 comprising means for connecting the two liquid compartments whereby the liquid which has been concentrated by indirect heat exchange collects in the first compartment, the inlet for the liquid to be evaporated is in the second liquid compartment and part of the concentrated liquid flows from the first to the second liquid compartment.
Claim 6
Dependent Claim
49 words
An apparatus according to claim 4, wherein said member which divides the lower part of the evaporation chamber into two liquid compartments is a partition which is located at the bottom of the evaporation chamber and which allows a flow of liquid between the liquid compartments over the partition.
Claim 7
Dependent Claim
37 words
An apparatus according claim 4, in which the partition is located below the heat exchanger so that at least part of the liquid concentrated by indirect heat exchange which flows downwardly flows into the first liquid compartment.
Claim 8
Dependent Claim
35 words
An apparatus according to claim 4, wherein a guiding surface is located between the heat exchanger and the partition in order to direct the liquid concentrated by indirect heat exchange into the first liquid compartment.
Claim 9
Independent Claim
106 words
A method of concentrating a liquid which when dilute would have a tendency to froth which comprises introducing the liquid into an evaporation zone, concentrating the liquid by expansion, simultaneously bringing a portion of the liquid in indirect heat exchange contact with a hot medium and concentrating said portion by indirect heat exchange, recycling part of the solution concentrated by indirect heat exchange to said indirect heat exchange zone, mixing the remainder of said concentrated solution with the liquid to be concentrated only by expansion, concentrating the combined portion by subjecting said combined portion to expansion evaporation and separately removing the vapor and the condensate liquid.
Claim 10
Independent Claim
106 words
A method of concentrating a liquid which when dilute would have a tendency to froth which comprises introducing the liquid into an evaporation zone, concentrating the liquid by expansion, simultaneously bringing a portion of the liquid in indirect heat exchange contact with a hot medium and concentrating said portion by indirect heat exchange, recycling part of the solution concentrated by indirect heat exchange to said indirect heat exchange zone, mixing the remainder of said concentrated solution with the liquid to be concentrated only by expansion, concentrating the combined portion by subjecting said combined portion to expansion evaporation and separately removing the vapor and the condensate liquid.
Claim 11
Dependent Claim
61 words
A method according to claim 8 wherein the liquid to be concentrated is sulfate black liquor obtained from the digestion of cellulose and the liquid to be evaporated is added to the liquid concentrated by indirect heat exchange in such an amount that the liquid to be recycled to the indirect heat exchange zone is at a minimum of 20% concentration.
Claim 12
Dependent Claim
24 words
The method according to claim 8 wherein the hot medium in the indirect heat exchange zone is the vapor removed from the expansion zone.
Claim 13
Dependent Claim
93 words
The process according to claim 8 wherein the concentrate removed from the evaporation zone after one stage is subjected to subsequent stages and at each stage only part of the liquid is subjected to indirect heat exchange, the entire liquid is evaporated by expansion, part of the liquid concentrated by indirect heat exchange is recycled to the indirect heat exchange zone and the remainder is combined with the liquid which is to be evaporated by expansion and the concentration of the liquid subjected to indirect heat exchange is at a minimum of 20%.
Claim 14
Dependent Claim
38 words
The process according to claim 11 wherein the portion of liquid subjected to indirect heat exchange is 19% in the first stage, 54% in the second stage, 59% in the third stage and 100% in the fourth stage.
Claim 15
Dependent Claim
70 words
A method according to claim 8, wherein in order to heat, by an indirect heat exchange contact, the liquid to be evaporated, the liquid is distributed evenly onto hot heat exchange surfaces and caused to flow substantially downwards along the heat exchange surfaces, whereafter concentrated liquid is recovered and part of it is recycled for distribution onto the heat exchange surfaces, together with the more dilute liquid to be evaporated.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-27 | 1981-08-29 | 1982-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-27 | 1985-08-29 | 1986-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-27 | 1989-08-29 | 1990-02-28 | $7700.00 | Window Closed / Lapsed |