GB2087422A - Process for removing ammonia and hydrogen sulfide from a vapor stream - Google Patents

Process for removing ammonia and hydrogen sulfide from a vapor stream Download PDF

Info

Publication number
GB2087422A
GB2087422A GB8133774A GB8133774A GB2087422A GB 2087422 A GB2087422 A GB 2087422A GB 8133774 A GB8133774 A GB 8133774A GB 8133774 A GB8133774 A GB 8133774A GB 2087422 A GB2087422 A GB 2087422A
Authority
GB
United Kingdom
Prior art keywords
ammonia
hydrogen sulfide
vapor stream
distillation
stream
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8133774A
Other versions
GB2087422B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
USS Engineers and Consultants Inc
Original Assignee
USS Engineers and Consultants Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by USS Engineers and Consultants Inc filed Critical USS Engineers and Consultants Inc
Publication of GB2087422A publication Critical patent/GB2087422A/en
Application granted granted Critical
Publication of GB2087422B publication Critical patent/GB2087422B/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10KPURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00Purifying combustible gases containing carbon monoxide
    • C10K1/08Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10KPURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00Purifying combustible gases containing carbon monoxide
    • C10K1/08Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/12Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Industrial Gases (AREA)
  • Treating Waste Gases (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

A process for the removal of hydrogen sulfide and ammonia from a vapor stream, and from a dilute aqueous solution containing free and fixed ammonia salts and acid gases comprises scrubbing the vapor stream in a scrubber (202) by contacting it with an aqueous ammonia solution, subjecting the dilute aqueous solution to a free and fixed ammonia still process (214, 224) passing an overhead vapor stream from the second still (224) through an indirect heat exchanger (226a) to heat the liquid in the first still (214) and then passing the overhead vapor stream to the scrubber (202) for the removal of the hydrogen sulfide. <IMAGE>

Description

SPECIFICATION Process for removing ammonia and hydrogen sulfide from a vapor stream The present invention relates to the removal of hydrogen sulfide and ammonia from a vapor stream.
Various methods have been proposed for removing hydrogen sulfide and ammonia from vapor streams such as coke oven gas. Hydrogen sulfide is generally removed from such vapor streams by passing the vapor stream through a hydrogen sulfide scrubber which is operated with aqueous ammonia as the scrubbing liquid. By maintaining a high concentration of ammonia in the scrubber relative to the concentration of hydrogen sulfide in the vapor stream, it is possible to remove high percentages such as over 98% of the hydrogen sulfide from the vapor stream.
Various ways have been suggested for removing the ammonia from the vapor stream and reusing this ammonia for the hydrogen sulfide scrubber. Some of these methods are descirbed in United States Patent Specification No. 4,009,243 which discloses distilling the wash waters from the hydrogen sulfide scrubber to produce a vapor stream of hydrogen sulfide and ammonia. This vapor stream and also the vapor stream leaving the hydrogen sulfide scrubber are then treated to separate the ammonia.
This treatment is accomplished by passing these vapor streams through one or more ammonia absorbers, such as those using aqueous ammonium phosphate solution. Ammonia vapors are then separated from the ammonia-enriched solution by distillation. These ammonia vapors are then recycled to the hydrogen sulfide scrubber.
According to the present invention, there is provided a process for removing hydrogen sulfide and ammonia from a vapor stream and from a dilute aqueous solution containing free and fixed ammonium salts and acid gases, the process comprising scrubbing said vapor stream in a hydrogen sulfide scrubber by contacting said vapor stream with an aqueous ammonia scrubbing solution to remove said hydrogen sulfide and produce an aqueous ammonia solution enriched with hydrogen sulfide, subjecting said dilute aqueous solution to a first counter-current multi-stage continuous distillation conducted by heating said solution by means of a stripping vapor, withdrawing from said first distillation an overhead vapor stream containing said acid gases in said solution and the ammonia from said free ammonium salts, withdrawing from said first distillation an aqueous bottom stream which contains substantially all of said fixed ammonium salts, adding alkali to said withdrawn bottom stream and thereafter subjecting said withdrawn bottom stream to a second counter-current multi-stage continuous distillation, withdrawing from said second distillation an aqueous bottom stream and an overhead vapor stream containing ammonia from said fixed ammonium salts, passing said overhead vapor stream from said second distillation through an indirect heat exchanger to partially condense said vapor stream, passing liquid from the first distillation through said indirect heat exchanger to produce said stripping vapor, and passing the ammonia in the second distillation overhead stream from the indirect heat exchanger into the hydrogen sulfide scrubber to provide at least in part the ammonia in said scrubbing solution.
The invention is further described, by way of example, with reference to the accompanying drawing which is a flow diagram illustrating a preferred embodiment of the invention.
Referring to the drawing, a vapor stream, such as coke oven gas, including acid gases and ammonia flow by line 201 into a hydrogen sulfide scrubber 202 where it is contacted with scrubbing liquids and vapors brought in by lines 203, 204, 205 and 206. An aqueous ammonia solution enriched with hydrogen sulfide leaves through line 217 and an ammonia-containing vapor stream passes through line 207 to an ammonia absorber 208 where the ammonia-containing vapor stream is contacted with a lean absorber solution such as an aqueous ammonium phosphate solution. The stripped vapor stream leaves through line 210 from the absorber 208. An ammonia-rich absorber solution leaves the absorber 208 through line 211 and passes on to a second ammonia absorber 212.
An aqueous solution, such as coke plant waste water, containing fixed and free ammonium salts and acid gases flows by line 213 into a first counter-current, multi-stage continuous distillation column 214. Overhead vapors containing acid gases, ammonia and water vapor leave the first distillation column 214 through line 21 5. The vapors in line 215 pass to a deacidification vessel 216 along with the aqueous ammonia solution enriched with hydrogen sulfide from line 217. Steam is added through line 21 8 to the deacidification vessel 21 6 to cause removal by distillation of ammonia and hydrogen sulfide which leaves through line 219 and passes to the second ammonia absorber 212. Bottom liquid from the vessel 21 6 passes through line 203 to the scrubber 202.A vapor stream containing acid gases leaves the second absorber 212 through line 220 and an ammonia-enriched absorber solution leaves the second absorber 212 through line 221. The ammonia can be removed from the absorber solution in line 221 by stripping.
The pH in the first distillation colum 214 is such that substantially all of the acid gases and substantially all of the ammonia from the free ammonium salts are removed from the aqueous solution passing into the column 214 from line 213. An aqueous bottom stream having a pH of less than 8 (preferably 5 to 6) and containing fixed ammonium salts passes from the column 214 through line 222.
Lime is added to this bottom stream at point 223. Precipitated solids may be removed at this point. The bottom stream, which now has a higher pH, passes into a second counter-current, multi-stage continuous distillation column 224 to which steam is added through line 226, and a vapor stream of substantially pure ammonia and steam leaves through line 225. An aqueous bottom stream with a pH of 9.5 to 12 leaves the second column 224 through line 227 where it may be passed to a biological treatment facility.
The vapor stream in line 225 is passed through an indirect heat exchanger 226a where liquid passing through lines 227 between the first distillation column 214 and heat exchanger 226a is vaporized to serve as stripping vapor for the first distillation. A partially condensed vapor stream from the heat exchanger 226a passes through line 228 and may be fed directly into the hydrogen sulfide scrubber 202 or, as shown, may be separated into liquid and vapor streams in a separator 229. An aqueous ammonia stream passes from the separator 229 through line 230. At this point, the aqueous ammonia stream may be passed through line 231 to the second distillation column 224 or may be passed through line 232 to the hydrogen sulfide scrubber 202.The ammonia vapor stream from the separator 229 passes through line 233 where it may go directly to the hydrogen sulfide scrubber 202 or, as shown, may pass through a condenser 234 where the vapor is converted to a liquid stream and passed on through line 204 to the scrubber 202.
The dilute aqueous solution supplied to the first distillation column 214 will typically contain CO2, H25, and HCN as well as the fixed and free ammonium salts. Commonly, the acid gases and free and fixed ammonium comprise up to about 0.6% by weight of the aqueous solution. Where the solution is waste water from coke plants or coal conversion plants, other components may include tars, phenols, fluorides, chlorides, sulfates, thiosulfates, and thiocyanates. In this circumstances, the tars would be removed by decanting. The waste waters from coke of other coal conversion plants are often referred to as ammoniacal liquors. The principal free and fixed salts present in the liquors are as foliows: Free Salts Fixed Salts ammonium carbonate ammonium chloride ammonium bicarbonate ammonium thiocyanate ammonium sulfide ammonium ferrocyanide ammonium cyanide ammonium thiosulfate ammonium sulfate In addition to ammonia and ammonium salts, the waste waters contain low concentrations of suspended and dissolved tarry compounds. The most important of these compounds are the phenols or "tar acids", the concentration of which usually ranges from about 0.3 to about 1 5 grams per liter of liquor. Pyridine bases, neutral oils, and carboxylic acids are also present in much lower concentrations.
The foilowing Table illustrates the range of compositions in coke plant waste water that comprise aqueous solutions especially suitable in the practice of the invention.
TABLE Typical Compositions, ppm Composition Waste Waste Waste Range, Water Water Water Component ppm No. 1 No.2 No.3 Free ammonia 450 to 10000 1900 770 1350 Fixed ammonia 700 to 4000 1900 1190 2440 Cyanide 2 to 1000 210 35 65 Sulfide O to 1300 500 1 10 Carbonate 150 to 4000 2180 190 350 Chloride 750 to 8500 2300 1920 4460 Sulfate/Sulfite 150 to 3000 310 325 415 Thiosulfate 90 to 600 440 115 300 Thiocyanate 100 to 1000 700 150 310 Total sulfur 200 to 2000 1300 250 550 Fluoride 30 to 150 60 40 75 Phenols 300 to 3600 1500 400 725 pH 7 to 9.1 9.0 7.5 7.6 The inlet feed temperature in the line 213 may be in the range of about 60 265 F, the overhead temperatures in the line 21 5 may be in the range of about 1 40a265a F, and the bottom temperatures in the line 222 may be in the range of about 1600--2750F. The first distillation will be conducted at a pressure in the range of about 0.3 to 3.0 atmospheres absolute. In this first distillation, substantially all of the free ammonium salts, e.g. sulfide, carbonate and cyanide, are decomposed into ammonia and acid gases that are removed by the stripping vapor.
The lime added at the point 223 reacts both with fixed ammonium salts to liberate ammonia and with any residual acid gases.
In the second distillation, the feed temperature in the line 222 may be in the range of about 1550--2700F, the overhead vapors in the line 225 may be at a temperature of about 1400--2900F, and the bottom stream in the line 227 may be at a temperature of about 1 600--2950F. The pressure may be up to about 4 atmospheres absolute. The bottoms stream from the second distillation will have a low concentration of total ammonia and of cyanides. The pH will be in the range 9.5-12. The total ammonia may be as low as 25 ppm. The total cyanides including complexed cyanides and free cyanides expressed in terms of equivalent HCN concentration, may be as low as 2 ppm; the free cyanides, (cyanides amendable to chlorination) in some cases may even be less than 1 ppm.This bottom stream can be clarified and then treated to remove other organic materials, such as phenols.
Passing the overhead vapor stream from the second distillation through an indirect heat exchanger to produce stripping vapor for the first distillation instead of using the overhead vapor stream from the second distallation avoids the introduction of extra ammonia into the first distillation and enables the pH in the first distillation to be kept low, preferably in the mildly acid range, so as to enhance the removal of acid gases in the first distillation.
By having substantially all of the acid gases and free ammonia removed in the first distillation, the second distillation can be conducted for the optimum removal of ammonia from the alkaline fixed ammonium salt solution. Also, the fixed ammonium salt solution will have minimal deposits of salts that would arise from the presence of the acid gases.

Claims (6)

1. A process for removing hydrogen sulfide and ammonia from a vapor stream and from a dilute aqueous solution containing free and fixed ammonium salts and acid gases, the process comprising scrubbing said vapor stream in a hydrogen sulfide scrubber by contacting said vapor stream with an aqueous ammonia scrubbing solution to remove said hydrogen sulfide and produce an aqueous ammonia solution enriched with hydrogen sulfide, subjecting said dilute aqueous solution to a first counter-current multi-stage continuous distillation conducted by heating said solution by means of a stripping vapor, withdrawing from said first distillation an overhead vapor stream containing said acid gases in said solution and the ammonia from said free ammonium salts, withdrawing from said first distillation an aqueous bottom stream which contains substantially all of said fixed ammonium salts, adding alkali to said withdrawn bottom stream and thereafter subjecting said withdrawn bottom stream to a second counter-current multi-stage continuous distillation, withdrawing from said second distillation an aqueous bottom stream and an overhead vapor stream containing ammonia from said fixed ammonium salts, passing said overhead vapor stream from said second distillation through an indirect heat exchanger to partially condense said vapor stream, passing liquid from the first distillation through said indirect heat exchanger to produce said stripping vapor, and passing the ammonia in the second distillation overhead stream from the indirect heat exchanger into the hydrogen sulfide scrubber to provide at least in part the ammonia in said scrubbing solution.
2. Process as claimed in claim 1, wherein said ammonia is introduced into the hydrogen sulfide scrubber as an aqueous ammonia stream.
3. Process as claimed in claim 1, wherein said ammonia is introduced into the hydrogen sulfide scrubber as a vapor stream.
4. Process as claimed in claim 1, wherein condensate produced in the indirect heat exchanger is returned to said second continuous distillation and wherein the uncondensed portion of the vapor stream is introduced into said hydrogen sulfide scrubber.
5. Process as claimed in claim 1, wherein both the condensed and uncondensed portions of said vapor stream from the heat exchanger are introduced into said hydrogen sulfide scrubber.
6. A process for removing hydrogen sulfide and ammonia from a vapor stream and from a dilute aqueous solution containing free and fixed ammonium salts and acid gases, substantially as hereinbefore described with reference to the accompanying drawing.
GB8133774A 1980-11-12 1981-11-09 Process for removing ammonia and hydrogen sulfide from a vapor stream Expired GB2087422B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US20612180A 1980-11-12 1980-11-12

Publications (2)

Publication Number Publication Date
GB2087422A true GB2087422A (en) 1982-05-26
GB2087422B GB2087422B (en) 1984-02-08

Family

ID=22765070

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8133774A Expired GB2087422B (en) 1980-11-12 1981-11-09 Process for removing ammonia and hydrogen sulfide from a vapor stream

Country Status (10)

Country Link
JP (1) JPS57145180A (en)
AU (1) AU7740381A (en)
BR (1) BR8107202A (en)
CA (1) CA1155637A (en)
DE (1) DE3137905A1 (en)
FR (1) FR2493723A1 (en)
GB (1) GB2087422B (en)
IT (1) IT8124952A0 (en)
RO (1) RO85214A (en)
SE (1) SE8106662L (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012495A1 (en) * 1988-06-23 1989-12-28 Still Otto Gmbh Process for removing hydrosulphide from coke oven gas
EP0521308A1 (en) * 1991-07-04 1993-01-07 Krupp Koppers GmbH Process for joint treatment of NH3 and/or H2S containing process waste waters as well as sodium sulfide containing caustic soda

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE360283C (en) * 1922-09-30 Johann Terwelp Dr Dephlegmator and preheater for ammonia abortion devices
US4009243A (en) * 1970-11-18 1977-02-22 Firma Carl Still Continuous process for scrubbing out hydrogen sulfide and ammonia from coke oven gas
DE2705280C2 (en) * 1977-02-09 1982-05-13 Dr. C. Otto & Comp. Gmbh, 4630 Bochum Process for stripping ammonia from solutions containing ammonia
NL7803765A (en) * 1978-04-10 1979-10-12 Hoogovens Ijmuiden Bv PROCESS FOR THE REMOVAL OF AMMONIA AND AMMONIUM SALTS FROM INDUSTRIAL WASTE WATER.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012495A1 (en) * 1988-06-23 1989-12-28 Still Otto Gmbh Process for removing hydrosulphide from coke oven gas
EP0521308A1 (en) * 1991-07-04 1993-01-07 Krupp Koppers GmbH Process for joint treatment of NH3 and/or H2S containing process waste waters as well as sodium sulfide containing caustic soda

Also Published As

Publication number Publication date
AU7740381A (en) 1982-05-20
GB2087422B (en) 1984-02-08
CA1155637A (en) 1983-10-25
SE8106662L (en) 1982-05-13
IT8124952A0 (en) 1981-11-10
DE3137905A1 (en) 1982-06-24
RO85214A (en) 1986-01-30
BR8107202A (en) 1982-07-27
FR2493723A1 (en) 1982-05-14
RO85214B (en) 1984-10-30
JPS57145180A (en) 1982-09-08
FR2493723B1 (en) 1984-12-28

Similar Documents

Publication Publication Date Title
US4594131A (en) Process for removing ammonia and acid gases from process streams
US4260462A (en) Process for separating acid gases and ammonia from dilute aqueous solutions thereof
US4111759A (en) Process for separating ammonia and acid gases from waste waters containing fixed ammonia salts
US4323430A (en) Process for separating ammonia and acid gases from streams containing fixed ammonia salts
US5236557A (en) Process for purification of aqueous solutions containing hydrogen sulfide, hydrogen cyanide, and ammonia
US2106734A (en) Gas purification process
US4060591A (en) Continuous process for recovering pure, concentrated ammonia
US4002565A (en) Waste-water process
US4105545A (en) Process for removing cyanide-containing components from aqueous media
CA1090281A (en) Process for separating acid gases and ammonia from dilute aqueous solutions thereof
US4104131A (en) Process for separating ammonia and acid gases from waste waters containing fixed ammonia salts
US3985863A (en) Process for the separation and recovery of ammonia and acid gases
MXPA03008336A (en) Process for producing ammonium thiosulphate.
US4522730A (en) Process for the treatment of an aqueous condensate
EP0857509A1 (en) Process for scrubbing ammonia and hydrogen sulfide from a fluid acid stream
CA1155637A (en) Process for removing ammonia and hydrogen sulfide from a vapor stream
US4778490A (en) Process for removal of volatile matter from coke-oven plant waters
EP0002880B1 (en) Regeneration of an absorbent liquid
US3804757A (en) Process for treating waste water from industrial processes
CA1093791A (en) Method of stripping chemically combined ammonia from the aqueous condensates and waste waters of low and high temperature carbonization processes
US1942050A (en) Gas purification
SU979492A1 (en) Process for purifying coking gas from acid components
GB2080274A (en) Method of recovering ammonia from process streams
GB2057411A (en) Process for the removal of hydrogen sulphide from gases
US4765969A (en) Continuous process for scrubbing hydrogen sulfide to produce elemental sulfur

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee