WO1997002885A1 - Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate - Google Patents

Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate Download PDF

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Publication number
WO1997002885A1
WO1997002885A1 PCT/GB1996/001603 GB9601603W WO9702885A1 WO 1997002885 A1 WO1997002885 A1 WO 1997002885A1 GB 9601603 W GB9601603 W GB 9601603W WO 9702885 A1 WO9702885 A1 WO 9702885A1
Authority
WO
WIPO (PCT)
Prior art keywords
alkali metal
agent
flue gas
weight
carbamate
Prior art date
Application number
PCT/GB1996/001603
Other languages
French (fr)
Inventor
Malcolm John Thorpe
Original Assignee
Brunner Mond (Uk) Limited
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 Brunner Mond (Uk) Limited filed Critical Brunner Mond (Uk) Limited
Priority to AU63134/96A priority Critical patent/AU6313496A/en
Priority to EP96922152A priority patent/EP0843586A1/en
Publication of WO1997002885A1 publication Critical patent/WO1997002885A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • B01D53/565—Nitrogen oxides by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/508—Sulfur oxides by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/68—Halogens or halogen compounds
    • B01D53/685—Halogens or halogen compounds by treating the gases with solids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/30—Alkali metal compounds
    • B01D2251/304—Alkali metal compounds of sodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/606—Carbonates

Definitions

  • the present invention relates to the treatment of flue gases.
  • flue gas as used herein relates to gases produced in industrial
  • Flue gases generally contain acidic gases which, if not removed prior to
  • Such acidic gases include sulphur oxides (SO nitrogen
  • flue gases For example, it is known to treat flue gases by injection of dry
  • powder sorbents e.g. CaO, Ca(OH) 2 , Na 2 C0 3 , NaHCO 3 , MgO, sodium
  • sesquicarbonate or mixtures thereof. These materials are generally more effective for
  • Techniques for reducing NO x gases include injection of ammonia gas into the
  • the method of the invention may be used for treating a flue gas containing
  • the amount of water in the treatment agent will not exceed 0.5% by
  • the water content does not exceed 0.2% by weight
  • the treatment agent comprises at least 3%, preferably 3% - 15% by
  • the balanc being substantially comprised of the
  • alkali metal bicarbonate and water (if present).
  • the alkali metal is sodium.
  • the treatment agent preferably has a maximum median particle size of 80
  • the treatment agent is comprised of alkali metal
  • the treatment agent may be prepared by reaction of an ammoniacal solution of
  • an alkali metal salt (preferably the halide, most preferably the chloride) with carbon
  • the treatment agent is produced from a saturated solution of the
  • alkali metal salt which is then substantially saturated with respect to ammonia prior to
  • the treatment agent is crude sodium bicarbonate as
  • the product may be dried at a temperature which reduces
  • the moisture content of the product (preferably to less than 0.5%) without causing
  • the effectiveness of the product may be further increased by addition of other
  • reducible nitrogen species e.g. ammonium carbamate, urea, ammonium bicarbonate
  • the treatment agent may be used in a number of ways.
  • the treatment agent may be used in a number of ways.
  • the treatment agent may be used in a number of ways.
  • agent may be injected into the flue gas using conventional injection equipment.
  • a filter will be provided in the flue gas stream to remove the solid product
  • the gas will be at least 150°C (e.g. in the range of 160°-300°C). This gives
  • the treatment agent should be
  • agent for use in reducing the content of acidic gases in a flue gas the agent for use in reducing the content of acidic gases in a flue gas

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treating Waste Gases (AREA)

Abstract

A method of treating a flue gas to reduce the content of acidic gases therein comprises treating the flue gas with an effect amount of a treatment agent which comprises an alkali metal bicarbonate and an alkali metal carbamate.

Description

FLUE GAS TREATMENT ITH MIXTURE OF ALKALI METAL BICARBONATE AND ALKALI METAL CARBAMATE
The present invention relates to the treatment of flue gases.
The term "flue gas" as used herein relates to gases produced in industrial
combustion processes. Thus, for example, flue gases are produced in the combustion
processes employed in power generation plant, waste incinerators, steam raising
boilers, glass production furnaces and metal refining furnaces.
Flue gases generally contain acidic gases which, if not removed prior to
discharge ofthe flue gas into the atmosphere, may cause an unacceptable deterioration
of air quality. Examples of such acidic gases include sulphur oxides (SO nitrogen
oxides (NO*) and hydrogen halides (HX).
Various processes are known and used for the removal of acidic gases from
flue gases. Thus, for example, it is known to treat flue gases by injection of dry
powder sorbents, e.g. CaO, Ca(OH)2, Na2C03, NaHCO3, MgO, sodium
sesquicarbonate, or mixtures thereof. These materials are generally more effective for
removing SOx and HX gases than NOx gases.
Techniques for reducing NOx gases include injection of ammonia gas into the
flue gas or, more conveniently, injection of urea as a solution or dry powder sorbent
into the flue gas.
When it is desired to reduce both SOx (and HX) and NOx gases it is generally
necessary to deploy a SOJHX reduction technique simultaneously or sequentially
with a NOx reduction technique. This does however require two different sorbents with the associated costs of purchasing and using each such separate sorbent via separate installations.
It is therefore an object of the present invention to obviate or mitigate the
abovementioned disadvantages.
According to a first aspect of the present invention there is provided a method
of treating a flue gas to reduce the content of acidic gases therein the method
comprising treating the flue gas with an effective amount of a treatment agent which
comprises a combination of an alkali metal bicarbonate and an alkali metal carbamate.
The method of the invention may be used for treating a flue gas containing
SOx> NOx or HX gases or any combination thereof.
The alkali metal bicarbonate is primarily effective for reducing SOx and HX
gases whereas the alkali metal carbamate provides a source of ammonia effective for
reducing NOx gases. Thus a single treatment agent may used for the reducing SOx,
HX and NOx gases in a flue gas. Ifthe flue gas contains SOx and NOx gases, reaction
of the SOx gases with the bicarbonate gives the alkali metal sulphate which catalyses
reduction of NOx gases.
Generally the amount of water in the treatment agent will not exceed 0.5% by
weight thereof.
It is highly preferred that the water content does not exceed 0.2% by weight,
even more preferably does not exceed 0.1% by weight, and most preferably does not
exceed 0.05%. Preferably the treatment agent comprises at least 3%, preferably 3% - 15% by
weight ofthe alkali metal carbamate, the balanc being substantially comprised ofthe
alkali metal bicarbonate and water (if present).
Preferably the alkali metal is sodium.
The treatment agent preferably has a maximum median particle size of 80
microns and is free flowing.
It is also preferred that the treatment agent is comprised of alkali metal
bicarbonate which has been co-produced with the alkali metal carbamate. The co-
production proceeds initially with crystallisation of the carbamate which provides nuclei on which the bicarbonate crystals grow. The resulting product is comprised of
particles of alkali metal bicarbonate which at least partially enclose the alkali metal
carbamate.
The treatment agent may be prepared by reaction of an ammoniacal solution of
an alkali metal salt (preferably the halide, most preferably the chloride) with carbon
dioxide. Preferably the treatment agent is produced from a saturated solution of the
alkali metal salt which is then substantially saturated with respect to ammonia prior to
carbonation.
The reaction of an ammoniacal solution of an alkali metal salt and carbon
dioxide produces a precipitate comprising particles of alkali metal bicarbonate which
at least partially enclose the alkali metal carbamate.
Most conveniently, the treatment agent is crude sodium bicarbonate as
produced during the Ammonia Soda process (also known as the Solvay process). This process involves reaction of carbon dioxide with ammoniacal brine (sodium chloride
solution) which initially produces a crude sodium bicarbonate containing sodium
carbamate. Normally this crude product is either converted to sodium carbonate or
refined to produce 'pure' sodium bicarbonate. However the crude product (possibly
after further treatment as described below) is eminently useful as a treatment agent for
use in accordance with the invention.
Thus, for example, the product may be dried at a temperature which reduces
the moisture content of the product (preferably to less than 0.5%) without causing
significant decomposition of the alkali metal carbamate and the bicarbonate. If
desired, the effectiveness of the product may be further increased by addition of other
reducible nitrogen species, e.g. ammonium carbamate, urea, ammonium bicarbonate
etc.
The treatment agent may be used in a number of ways. Thus, for example, the
agent may be injected into the flue gas using conventional injection equipment.
Generally a filter will be provided in the flue gas stream to remove the solid product
resulting from reaction of the treatment agent and acidic gases. If the flue gas to be
treated contain only SOx and/or HX gases, then it is convenient that injection of the
treatment agent takes place at a position close to the filter where the temperature of
the gas will be at least 150°C (e.g. in the range of 160°-300°C). This gives
stoichiometric reduction of SOx and HX gases.
It is however more preferred to introduce the treatment agent into or close to
the combustion zone where the temperature is sufficiently high to cause possible decrepitation (i.e. auto-disintegration of the agent into smaller particles) thus
increasing the surface area of the treatment agent and rendering it more effective for
removal of acid gases. To achieve decrepitation, the treatment agent should be
introduced into the flue gas at a region where the temperature thereof is 500 to
1000°C, more preferably 750 to 900°C. Such temperamres also cause reduction of
NOx gases.
Certain of the treatment agents described herein are novel compositions and
therefore according to a second aspect ofthe present invention we provide a treatment
agent for use in reducing the content of acidic gases in a flue gas, the agent
comprising a combination of an alkali metal bicarbonate and an alkali metal carbamate, the agent optionally containing water in an amount no more than 0.5% by
weight.
Preferred features of the treatment agent described in relation to the first aspect
of the invention are also applicable to the second aspect.

Claims

1. A method of treating a flue gas to reduce the content of acidic gases therein the
method comprising treating the flue gas with an effective amount of a treatment agent
which comprises a combination of an alkali metal bicarbonate and an alkali metal
carbamate.
2. A method as claimed in claim 1 wherein the agent optionally contains water in
an amount of up to 0.5% by weight.
3. A method as claimed in claim 2 wherein the agent optionally contains water in
an amount up to 0.2% by weight.
4. A method as claimed in claim 3 wherein the agent optionally contains water in
an amount up to 0.1% by weight.
5. A method as claimed in claim 4 wherein the agent contains water in an amount
up to 0.05% by weight of water.
6. A method as claimed in any one of claims 1 to 5 wherein the agent contains at
least 3% ofthe alkali metal carbamate.
7. A method as claimed in claim 6 wherein the agent contains 3 to 15% by
weight ofthe alkali metal carbamate.
8. A method as claimed in any one of claims 1 to 7 wherein the alkali metal is
sodium.
9. A method as claimed in any one of claims 1 to 8 wherem the treatment agent is
comprised of particles of alkali metal bicarbonate which at least partially enclose the
alkali metal carbamate.
10. A method as claimed in any one of claims to 1 to 9 wherein the treatment
agent has been prepared by a reaction of an ammonical solution of an alkali metal salt
with carbon dioxide.
11. A method as claimed in any one of claims 1 to 10 wherein the treatment agent
is introduced into the flue gas at a region where the temperature thereof is in the range
of l60°C to 300°C.
12. A method as claimed in any one of claims 1 to 10 wherein the treatment agent
is introduced into the flue gas at a region where the temperature thereof is in the range
of500 to lOOO°C.
13. A method as claimed in any one of claims 1 to 12 wherein the treatment agent
is introduced into the flue gas at a region where the temperature thereof is in the range
of 750 to 900°C.
14 A method as claimed in any one of claims 1-13 wherein the treatment agent is
injected into the flue gas.
15. A treatment agent for use in reducing the content of acidic gases in a flue gas,
the agent comprising a combination of an alkali metal bicarbonate and an alkali metal
carbamate, the agent optionally containing water in an amount no more than 0.5% by
weight.
16. An agent as claimed in claim 15 wherein the agent optionally contains water in
an amount up to 0.2% by weight.
17. An agent as claimed in claim 16 wherein the agent optionally contains water in
an amount up to 0.1 % by weight.
18. An agent as claimed in claim 17 wherein the agent contains water in an
amount up to 0.05% by weight of water.
19. An agent as claimed in any one of claims 15 to 18 wherein the agent contains
at least 3% ofthe alkali metal carbamate.
20. An agent as claimed in claim 19 wherein the agent contains 3 to 15% by
weight ofthe alkali metal carbamate.
21. An agent as claimed in any one of claims 15 to 20 wherein the alkali metal is
sodium.
PCT/GB1996/001603 1995-07-08 1996-07-04 Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate WO1997002885A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU63134/96A AU6313496A (en) 1995-07-08 1996-07-04 Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate
EP96922152A EP0843586A1 (en) 1995-07-08 1996-07-04 Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9513989.5A GB9513989D0 (en) 1995-07-08 1995-07-08 Treatment of flue gases
GB9513989.5 1995-07-08

Publications (1)

Publication Number Publication Date
WO1997002885A1 true WO1997002885A1 (en) 1997-01-30

Family

ID=10777370

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/001603 WO1997002885A1 (en) 1995-07-08 1996-07-04 Flue gas treatment with mixture of alkali metal bicarbonate and alkali metal carbamate

Country Status (4)

Country Link
EP (1) EP0843586A1 (en)
AU (1) AU6313496A (en)
GB (1) GB9513989D0 (en)
WO (1) WO1997002885A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2131019A1 (en) * 1997-10-10 1999-07-01 Unisystems S A Procedure for the purification of smoke which contains acid contaminants.
EP1155730A1 (en) * 2000-05-17 2001-11-21 Asahi Glass Co., Ltd. Method for treating a gas containing SO3 using Na2CO3
DE102009035714A1 (en) * 2009-07-31 2011-02-03 Brewa Wte Gmbh Method for removing toxic substance from flue gas in waste incinerator utilized for combustion of waste, involves introducing reactant into flue gas stream at flue gas temperature, where reactant reacts with toxic substance to be removed

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942610A (en) * 1932-03-02 1934-01-09 Mathieson Alkali Works Inc Process for production of water soluble metal carbamates
US2067013A (en) * 1935-10-02 1937-01-05 Mathieson Alkali Works Inc Process for producing the disodium salt of imidodicarboxylic acid
WO1992002291A1 (en) * 1990-08-01 1992-02-20 Nalco Fuel Tech Gmbh Process for the in-line hydrolysis of urea
EP0506132A1 (en) * 1991-03-29 1992-09-30 Oriental Technical Research Industry Co., Ltd. Method for removal of mercury in exhaust gas
WO1993007087A1 (en) * 1991-10-03 1993-04-15 Nalco Fuel Tech Hardness suppression in urea solutions
JPH05146492A (en) * 1991-11-26 1993-06-15 Matsushita Electric Works Ltd Deodorant

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942610A (en) * 1932-03-02 1934-01-09 Mathieson Alkali Works Inc Process for production of water soluble metal carbamates
US2067013A (en) * 1935-10-02 1937-01-05 Mathieson Alkali Works Inc Process for producing the disodium salt of imidodicarboxylic acid
WO1992002291A1 (en) * 1990-08-01 1992-02-20 Nalco Fuel Tech Gmbh Process for the in-line hydrolysis of urea
EP0506132A1 (en) * 1991-03-29 1992-09-30 Oriental Technical Research Industry Co., Ltd. Method for removal of mercury in exhaust gas
WO1993007087A1 (en) * 1991-10-03 1993-04-15 Nalco Fuel Tech Hardness suppression in urea solutions
JPH05146492A (en) * 1991-11-26 1993-06-15 Matsushita Electric Works Ltd Deodorant

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DATABASE CHEMABS CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; FILIPESCU, LAURENTIU ET AL: "Mechanism of sodium bicarbonate crystallization", XP002017025 *
DATABASE WPI Section Ch Week 9328, Derwent World Patents Index; Class A97, AN 93-223563, XP002017026 *
REV. CHIM. (BUCHAREST) (1983), 34(11), 1000-3 CODEN: RCBUAU, 1983 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2131019A1 (en) * 1997-10-10 1999-07-01 Unisystems S A Procedure for the purification of smoke which contains acid contaminants.
EP1155730A1 (en) * 2000-05-17 2001-11-21 Asahi Glass Co., Ltd. Method for treating a gas containing SO3 using Na2CO3
US6780385B2 (en) 2000-05-17 2004-08-24 Asahi Glass Company, Limited Method for treating a gas
DE102009035714A1 (en) * 2009-07-31 2011-02-03 Brewa Wte Gmbh Method for removing toxic substance from flue gas in waste incinerator utilized for combustion of waste, involves introducing reactant into flue gas stream at flue gas temperature, where reactant reacts with toxic substance to be removed

Also Published As

Publication number Publication date
AU6313496A (en) 1997-02-10
EP0843586A1 (en) 1998-05-27
GB9513989D0 (en) 1995-09-06

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