JP2000296311A - ABSORBENT FOR REMOVING SOx, NOx AND CO2 IN WASTE GAS, REGENERATION AND RECYCLE USE OF ABSORBENT AND EFFECTIVE USE OF BY-PRODUCT (CHEMICALS) BY REACTION PRODUCT WITH WASTE GAS COMPONENT - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate, circulate, recycle and use an absorbent and to use by-product effectively by precipitating the synthetic compd. formed by the neutralization of the absorbent for removing the harmful gas in waste gas and the harmful gas and by decomposing by heating and electrolyzing the precipitate. SOLUTION: In the means in which salt is used as the starting material of the absorbent, and the sodium hydroxide raw soln. obtained by electrolysis is used effectively to the pH 13 adjusting absorbent soln. at the time of initial soln. rising for a by-product and the soln. for replenishing, and the synthetic compd. formed by the neutralization of the absorbent and the harmful gas to be removed is precipitated. decomposed by heating and electrolyzed and a strongly basic alkali component of >=pH 13.5 is converted to regenerated circulating absorbing soln. and the soln. is circulated, recycled and used repeatedly, and the lost regenerated circulating absorbing soln. is replenished with the soln. for replenishing, and a by-product starting material generated at the time of thermal decomposition and a by-product starting material generated at the time of the electrolysis are absorbed in the soln. for a by-product, the effective use of the by-product is executed by absorbing the residual CO2 after removing the harmful gas in the waste gas in the soln. for the by-product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to equipment for harmful gases such as SOx, NOx, CO
_{(2) The present invention} relates to regeneration and recycle use of an absorbent and effective use of by-products by thermal decomposition and electrolysis of a precipitate obtained by precipitating a synthetic compound generated by a ₂ removal absorbent and a harmful gas and a neutralization reaction.

[0002]

2. Description of the Related Art The lime method uses a lime slurry as an absorbent, and after a neutralization reaction with SO ₂ in exhaust gas, a by-product of the absorbent,
Gypsum is collected, the absorption solution separated from gypsum is adjusted for pH, and drained after air oxidation so that COD of water quality is not affected.
The equipment is large and the economic burden of equipment costs is large, and the lime method has a problem that the equilibrium reaction that generates CO ₂ at the same time as the removal reaction of SOx by desulfurization emits CO ₂ , a global warming factor. SOx and semi-dry lime method, economical comparison of absorbent (attached attachment).

2, desulfurization of magnesium hydroxide absorbent,
The magnesium hydroxide absorption solution is brought into gas-liquid contact with SO ₂ in the exhaust gas, and after the neutralization reaction, the pH of the absorption solution is adjusted.
Draining after air oxidation so as not to be affected by OD, no post-treatment equipment cost for waste water, removal component SOx, by-product recovery and absorbent regeneration system installed not attached, when fitted with a device, the device body is complicated, and requires a catalyst regeneration affects the desulfurization costs, economy compared byproducts SO ₂ absorber (Appendix attached)

[0004] 3. Desulfurization method of sodium hydroxide absorbent, adjusting the alkali component of sodium hydroxide absorption solution to pH 8 or less, which is not affected by the influence of CO _{2 in} the exhaust gas, and neutralizing with SOx in the exhaust gas. Adjusting the pH of the absorbed solution, draining after air oxidation so as not to be affected by COD of water quality, no post-treatment equipment cost for drainage, removal component SOx, by-product recovery and absorbent regeneration and recycling equipment, desulfurization If the equipment is installed, it will not be generally installed because it will increase the cost. When the equipment is installed, the reactant accumulates in the absorbent due to the generation of sodium sulfate and sodium nitrate, causing the deterioration of the regenerated absorbent and the effect of absorption of the absorbent The main by-product SO ₂ ,
Sodium sulfite, sodium sulfate, sodium nitrate,
Sodium absorbent desulfurization hydroxide, sulfate recovery system (Wellman load method) production apparatus, the SO ₂ during desulfurization, after absorbed in sodium hydroxide absorption solution, thermolysis absorption solution, SO
₂ gas SO ₃ oxidation in catalyst, sodium sulphate recovered sulfate, problems, degradation of the recycled absorber, the effect of absorption of the absorbent in the course used, produced oxidized by O ₂ in the gas composition of the combustion exhaust gas The reaction product with NOx, sodium nitrate,
Decrease in the generation of neutral salts etc., absorbent cost and, for recovering the absorbent solution directly heated decomposed SO ₂ gas, SO
₍₂ ) The problem of high sulfuric acid cost due to low gas concentration and economic comparison of absorbents (attached in the attached sheet).

[0005] 4. Ammonia water desulfurization method, a method of adjusting ammonia water to pH around 6, draining after desulfurization, recovering ammonium sulfate as a by-product, and heat absorbing SO
₂ After the recovery, the absorbent solution can be recycled and reused, but the economical efficiency of desulfurization is low. In the basic principle of desulfurization, neutralization of acid and alkali, the ratio of absorbent used for neutralizing SO ₂ is SO
_{2 1:} NH 3 0.54, a ratio of the (ammonia 100% conversion), provided that when fitted with absorbent regeneration recycle apparatus, _{O 2} and oxidized products in the exhaust gas, ammonium sulfate Recovered as a by-product, following the cause of deterioration of the absorbent, comparing the economics of the absorbent (attached in the attached sheet).

5, urea absorbent desulfurization, denitration method The operating ratio is low due to cost and equipment cost problems, and the removal components SOx and NO
x.

[Problems to be solved by the invention]

[0007] The above-mentioned conventional techniques 1 to 5 of the currently used desulfurization method absorbents are based on the principle of acid and alkali neutralization reaction as the basic technique of the method for removing SO _{2 from} exhaust gas.
After the neutralization reaction with SO ₂ in the exhaust gas, the pH of the absorbing solution absorbing SO ₂ is adjusted, and the solution is drained after air oxidation.
Even if absorbents with renewable conditions of 5 are economical problems such as equipment costs and desulfurization costs within the range permitted by laws and regulations, even if there is a problem with post-treatment of wastewater, rivers The lime slurry of the lime method, which must take soil and water pollution into consideration when drained to
After the neutralization reaction with ₂ , gypsum is produced as a by-product after air oxidation. If the utility value of gypsum is industrially available or an economic problem arises, industrial waste will be produced in that situation. gypsum is accumulate requires a land reclamation as objects, problems of economic cost burden, lime method, the equilibrium reaction products CO ₂ to generate the SO ₂ upon removal desulfurization is global warming The absorbent of the present invention, which is a factor problem, has no waste generation problem. The absorbent is recycled and recycled without drainage, and the absorbent is effectively used up to the limit of use. allowing reduced to 20 or less, as pollution-free absorbent which does not cause generation of water soil pollution environmental issues, also SOx harmful gas removal, NOx, the product compound of CO _2, when performing reproduction available for absorption agent at the same time Effective use as a by-product It is an object to provide an absorbent that.

[Means for Solving the Problems]

[0008] In order to achieve the above object, the absorbent of the present invention is obtained by electrolyzing an ionic crystal compound and an inexpensive salt (NaCl) solution in (first raw material of the absorbent) to obtain an electrolytic solution. (2 Absorbent) The stock solution of sodium hydroxide solution (NaOH) was adjusted to around pH13 at the start-up of the initial operation and used for absorption solution, 2, for by-products, used as raw material solution for absorption, and at pH13 The problem is solved by adjusting and using it in a replenishing absorption solution of a recirculating absorbent.

(Second absorbent) sodium hydroxide solution (N
aOH) p at the start of initial operation
The absorption solution (third absorbent) adjusted to around H13 is mixed with acidic harmful gas SOx (90%) and NOx (1
5%) and CO ₂ (20%) are simultaneously absorbed into the absorbing solution by a neutralization reaction to solve the problem.

Toxic gases SOx, NOx, CO in exhaust gas
Simultaneous removal and neutralization reaction of ₂ and absorbed product compound, sodium hydrogen sulfite (NaHSO ₃ ) + sodium hydrogen carbonate (NaHCO ₃ ) + sodium nitrate (NaNO ₃ ) +
Neutral salts such as sodium sulfate (Na ₂ SO ₄ ) / weak base p
The present invention solves the problem, characterized in that the generated synthetic compound (fourth absorbent) of H5 to H6 is precipitated in the course of circulating use and separated from the absorbing solution.

[0011] The synthetic compound precipitated and produced by the (fourth absorbent) is thermally decomposed at a temperature within 100 to 200 ° C.
SO ₂ gas (by-product raw material) + CO ₂ gas (absorbent raw material) and sodium sulfite (NaSO ₃ ) + sodium carbonate (Na ₂ CO ₃ ) + sodium nitrate (NaNO 3) +
The problem is solved by decomposing into a synthetic compound generated in sodium sulfate (Na ₂ SO ₄ ) and obtaining an absorbent of a basic alkali component (fifth absorbent) having a pH of about 8.7 by thermal decomposition. .

[0012] The (fifth absorbent) obtained by thermal decomposition is used as a solution for electrolysis. Sodium sulfite (NaSO ₃ ) as a basic alkali component having a pH of about 8.7 + sodium carbonate (Na ₂ CO ₃ ) + sodium nitrate (NaNO 3) + sodium sulfate (Na ₂ SO ₄ ) -absorbing solution is replaced with hydroxide ion OH ⁻ by electrolysis, and an alkali component raw material that performs a neutralization reaction on average around 13.5 (sixth absorbent) The problem is solved by being obtained by electrolysis into an absorption solution of a strong base alkali component.

The neutral salt of a stable product, sodium nitrate (NaNO 3) + sodium sulfate (Na ₂ SO ₄ ), pH 6.2, which coexists in the (fifth absorbent) also has a solution electrolysis law of NO ₃ ⁻ , SO ₄ ^2- , OH ⁻ → O ₂ } and Na, H
^{The present invention} solves the problem by being replaced by ¹ → H ² }, electrolyzed to a strong base alkali component having an average of about 13.7, and also reducing nitrate ions and sulfate ions in sodium nitrate and sodium sulfate by electrolysis.

The regenerated circulating absorption solution obtained by adjusting the pH of the electrolyzed (sixth absorbent) to around 13 is mixed with acidic harmful gases SOx (90%), NOx (15%), and CO _{2 in} flue gas.
The problem is solved by simultaneously removing the (20%) rate, repeating the absorption in the regenerated circulating absorption solution by the neutralization reaction, and performing circulating recycling.

The scale loss during the absorption reaction and the loss during the thermal decomposition and electrolysis of the primary absorption solution (third absorbent) and the secondary recycle circulating absorption solution are compared with the initial (third absorbent) water The object is solved by replenishing a sodium oxide solution (NaOH) with an adjusted absorption solution having a pH of 13 and repeatedly performing recycle use.

SOx (90%), NOx in combustion exhaust gas
(15%) and CO ₂ (20%) rate are simultaneously removed and the absorption solution after the neutralization reaction is not discharged to the outside at all. Solve the problem with the features.

By-product 1) (First absorbent material) Salt (NaC
l) Chlorine gas (C)
l ₂ ), hydrogen gas (H ₂ ) is heated by compounding, and the hydrogen gas is burned and synthesized into hydrogen chloride (HCl).
(Second absorbent) Chlorine gas (Cl ₂ ) is introduced into a solution raw material for a by-product of a sodium hydroxide solution to make a saturated solution, and a salt (N
A problem is solved by effectively utilizing by-products (industrial chemicals) such as aCl) regenerated raw materials for electrolysis and sodium hypochlorite sodium chloride (NaClO) solution in industry for cycle use.

By-product 2) Synthetic compound produced in absorption solution from which harmful gas in exhaust gas was removed, sodium hydrogen sulfite (NaHSO ₃ ) + sodium hydrogen carbonate (NaHCO ₃ )
₃ ) + sodium nitrate (NaNO ₃ ) + sodium sulfate (Na ₂ SO ₄ ) generated synthetic compound precipitate is thermally decomposed, and high-concentration SO ₂ (by-product raw material) is converted to vanadium pentoxide (V ₂ O). ₅ ) High-concentration SO ₂ (by-product raw material) by adding SO ₃ oxidized through a catalyst to sulfuric acid (H ₂ SO ₄ ) by-product and sodium hydroxide (NaOH) solution of (second absorbent) in initial salt solution electrolysis. Absorbs CO ₂ (absorbent raw material) coexisting with water, and uses sodium sulfite (NaSO ₃ ) by-product and sodium carbonate (Na ₂ CO ₃ ) absorbent raw material as an absorbent, and the by-product is (industrial chemical) as industrial recycling The problem is solved by using it effectively for use.

By-product 3) SOx (90
%), NOx (15%), and CO ₂ (20%) rate, and then the residual CO ₂ of the exhaust gas is reduced to 95% by activated carbon catalyst.
Pretreatment for removal, (second absorbent) sodium hydrogen carbonate (NaH) absorbed and saturated in sodium hydroxide solution raw material
The CO ₃₎ heated sodium carbonate _(Na 2 CO ₃₎ by-products (industrial chemicals), the recycling industry, that the effective use of CO ₂ in the exhaust gas, to solve the problems is characterized.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. In FIG. (First absorbent material) Salt (NaCl) is made into a solution and 2. 4. With electrolysis
(Second absorbent) A stock solution of sodium hydroxide (NaOH) solution can be obtained. Chlorine gas (C
l ₂ ), 4. Used as (by-product raw material) that generates hydrogen gas (H ₂ ).

In FIG. (Second absorbent) Use of undiluted solution of sodium hydroxide (NaOH) solution, application, 6. The absorption solution for initial operation startup is 9. (Third absorbent) pH
13 to the adjusted absorption solution; Solution raw material for by-products is 22. 27. For sodium hypochlorite by-product, 30. For sodium sulfite by-product 7. For sodium carbonate by-product The replenishment absorption solution is 19. The (seventh absorbent) is divided and used for absorption reaction loss, heat decomposition, replenishment of absorption solution for loss during electrolysis, and the like.

In FIG. 8. The absorption solution at the start-up of the initial operation 8. supply to (Third absorbent) adjusts the absorption solution to pH 13, and adjusts SOx, (9
(0%) NOx, (15%) CO ₂ (20%) rate was removed simultaneously after gas-liquid contact and neutralization reaction, and absorbed in the absorbing solution.
11.12.13.14.15.16.16.17.18.1
9. Is played back once, and 9. Returning to step 1 as the first recycle absorption solution, To 9. The supply of the absorbing solution at the start-up of the initial operation is stopped, and the first recirculating absorbing solution is replaced and the recycled solution is reused.

The first regenerated recycle absorption solution replaced is 9. In SOx in the combustion exhaust gas, NOx, CO ₂ and liquid contact, after the neutralization reaction, is absorbed into the absorbent solution 10.1
1.12.13.14.15.16.16.18.18.1
9. 8. The recycled circulation absorption solution regenerated from And recycle and recycle use.

In FIG. (Fourth absorbent) 1,
The SOx (90
%), NOx (15%) and CO ₂ (20%) were absorbed into the absorbing solution by the neutralization reaction. (Fourth absorbent)
2, 12. Sodium bisulfite (NaHSO ₃ ) +
13. Sodium bicarbonate (NaHCO ₃ ) and sodium nitrate (NaNO ₃ ) + sodium sulfate (Na ₂ SO
₄ ) Formation of neutral salt / weak base at pH 5-6 The synthesized compound is precipitated in the course of circulating use and separated from the absorbing solution.
The chemical reaction between the removal harmful gas and the absorbing solution is as follows. 1) SO ₂ reaction _{2NaOH + SO 2 → Na 2 SO} 3 + H 2 O Na 2 SO 3 + H 2 O → 2NaHSO 3 2) CO 2 reaction _{2NaOH + CO 3 → Na 2 CO} 3 + H 2 O Na 2 CO 3 + H 2 O + CO 2 → 2NaHCO ₃ 3) NO reaction NO + 1 / 2O ₂ → NO ₂ 2NaOH + 2NO ₂ → NaNO ₃ + NaNO ₂ + H ₂ O NO ₂ + NO + 2NaOH → 2NaNO ₃ + H ₂ O 4) SO ₄ reaction Na ₂ SO ₃ + 1 / 2O ₂ → Na ₂ SO ₄

In FIG. (Fifth absorbent) is 1
2.13. And sodium nitrate (NaNO ₃ ) + sodium sulfate (Na ₂ SO ₄ ) having a pH of 5 to 6 and a neutral salt / weak base formed synthetic compound precipitate were subjected to 100-200.
11. heat decomposition in the range of ° C. Is 15. Sodium sulfite (Na ₂ SO ₃ ) +13. Is 16. Sodium carbonate (Na ₂ CO ₃ ) and sodium nitrate (NaNO ₃ ) +
16. Synthetic compound in which a basic alkali component of about sodium sulfate (Na ₂ SO ₄ ) pH 8.7 is generated. (Fifth absorbent) and SO ₂ (by-product raw material) CO ₂ (absorbent raw material) are thermally decomposed into CO ₂ (absorbent raw material). The chemical reaction of thermal decomposition into the recycled circulation absorption solution of (fifth absorbent) is as follows. 1) 2NaHSO ₃ → Na ₂ SO ₃ + H ₂ O + SO ₂
↑ 2) 2NaHCO ₃ → Na ₂ CO ₃ + H ₂ O + CO ₂
↑ 3) Sodium sulfate, sodium nitrate 100-200 ° C
Stable in the range of thermal decomposition

In FIG. (Sixth absorbent) is 1
7. 14. obtained by thermal decomposition of (fifth absorbent); Sodium sulfite (Na ₂ SO ₃ ) +16. Sodium carbonate (N
a ₂ CO ₃ ) and sodium nitrate (NaNO ₃ ) + sodium sulfate (Na ₂ SO ₄ ) A synthetic compound having a pH of about 8.7 and a base alkali component is formed into a solution, and electrolysis is performed. 18. A raw material of a strongly basic alkali component having an average pH of 13.5 or more.
(Sixth absorbent) It can be electrolyzed to the regenerated circulating absorbent.

The following table shows the results of electrolysis experiments of the following compounds for removing the acidic harmful gas and the composition of the exhaust gas.

In FIG. Sodium sulfate (Na ₂ SO ₄ ) and thorium nitrate (N) generated by gas-liquid contact with SOx, O ₂ , and NOx in the exhaust gas by the (fourth absorbent)
ANO ₃₎ stable product compounds such as neutral salt pH6.2 also the solution and the electrolyte ^{_{law, NO 3, SO4 2, OH}} → O 2
↑ and Na, H ¹ → H ₂電解 are replaced by an electrolytic reaction
H13.7 to strong base alkali components around 13.7. (Sixth absorbent) Electrolyte, and also reduce nitrate ion and sulfate ion of sodium nitrate and sodium sulfate. (Sixth absorbent).

1) The following are the absorbents SOx, NOx, CO
_2. Absorbent performance at the time of absorption, thermal decomposition, electrolysis, and repeated use of recycle The confirmation results of the alkaline components are shown in the following table: 70% of the reagent (NaHSO ₃ ) used in the experiment, (NaH
(CO ₃ ) 15%, (NaNO ₃ ) 5%, (Na ₂ S)
O ₄ ) 5%, (Na ₂ S ₂ O ₅ ) 5% 1N. 100m
l.

2) The following shows a list of the results of comparative verification ion analysis of a stable compound, sodium nitrate (NaNO ₃ ), sodium nitrate ion and sodium ion decrease after electrolysis of sodium sulfate (Na ₂ SO ₄ ) with a reagent. (Sample, using the above experimental sample).

In FIG. (Seventh absorbent)
18. The strong base alkali component having an average pH of 13.5 or more obtained by electrolysis of the (sixth absorbent) is subjected to SOx (90
_{%), NOx (15%)} CO 2 (20%) rate after simultaneous removal can pH13 adjust the playback circulating absorbent solution back and forth, through regeneration recycle absorbent line 9. Return to (Third absorbent).

In FIG. (Seventh absorbent) replenishes for the loss of absorbent during absorption reaction, thermal decomposition, and electrolysis. Supplied from make-up absorption solution.

In FIG. By-product 1) is 1.
(First absorbent material) generated by electrolysis of salt (NaCl),
3. Chlorine gas (Cl ₂ ) 4. Combined heating of hydrogen gas (H ₂ ) to burn hydrogen gas. After synthesis into hydrogen chloride (HCl), 21. 6. By-product, hydrochloric acid, As a solution raw material for by-products,
3. 23. Introduce chlorine gas (Cl ₂ ) to make a saturated solution,
22. salt (NaCl) electrolytic regeneration raw material; It is a by-product such as sodium hypochlorite (NaClO) solution.

In FIG. By-product 2) is 1
5. Sodium sulfite + SO ₂ (by-product raw material)
5. 7. For SO ₂ raw material, The byproduct solution material to absorb SO _2, heated in a saturated solution, 27. 25. After oxidizing SO ₂ by-product to sodium sulfite (Na ₂ SO ₃ ) by-product through vanadium pentoxide catalyst (V ₂ O ₃ ) to SO ₃ ,
11. Sulfuric acid (H ₂ SO ₄ ) by-product The sodium bisulfite (NaHSO ₃ ) precipitate is separated and precipitated by the recrystallization method.
8. By-products such as sodium sulfate, 29 and sodium nitrate are obtained.

In FIG. By-product 3) is composed of SOx (90%) and NOx (15%) CO ₂ (20%) in the exhaust gas.
%), The residual CO ₂ of the exhaust gas is further removed by an activated carbon catalyst, and NO is removed by 95% or more. 30. Absorbed by-product solution material, heated saturated solution of sodium bicarbonate;
High purity sodium carbonate by-product can be obtained.

[0036]

Since the present invention is configured as described above, it has the following effects.

The absorbent of the present invention is a compound of an ionic crystal,
Inexpensive salt (NaCl) as (first absorbent material), Na
(Metallic sodium), electrolysis of solution, NO ₃ ⁻ , S
^{_{O 4 2-, OH - → O}} 2 ↑ and Na, ^{_H 1} → ^H ₂ ↑ replacement ionization reaction, acid, the product compound by a chemical reaction and thermal decomposition of the hydrogen ion ^{H 1} and a base hydroxide ions OH bases Absorption of harmful gas in exhaust gas by absorbent using the law of decomposition, etc. by neutralization reaction, regeneration of generated synthetic compound into absorbent, effective use of by-products and overall effect of absorbent reaction Is done.

Uses of sodium hydroxide solution (NaOH) stock solution obtained by salting and electrolysis. 1. For initial operation start-up, use of absorption solution; 2. Use of solution raw materials for by-products;
The use of the replenishing absorption solution and the like plays the whole role of constituting the absorbent such as the use of the recycled circulating absorbent and the by-product.

The adjustment of the pH 13 region of the absorption solution is performed by using SOx
(90%), NOx (15%) and CO ₂ (20%) at the same time.

The absorption of the absorbent is effected by separating the harmful gas components into the absorption solution by the neutralization reaction and thereby separating the precipitate of the synthetic compound and the absorption solution, and the efficiency of decomposition of the absorbent and by-product raw materials during thermal decomposition. And high concentration gas of by-product raw materials SO ₂ and CO ₂ can be obtained.

The effect of absorbing CO ₂ in the exhaust gas into the absorbing solution, heating and decomposing the absorbing solution, and then reusing the absorbing solution as an alkaline component, sodium carbonate (Na ₂ CO ₃ ).

By the thermal decomposition, the absorbing solution having absorbed the harmful gas is separated from the recycled circulating absorbent and the by-product raw material (SO ₂ ) and the absorbent raw material (CO ₂ ) for effective use.

The electrolysis of the absorbing solution is based on the principle of neutralization of acid and alkali, and the compound absorbed in the absorbing solution from which the acidic harmful gas has been removed is precipitated and decomposed by heating. An effective use effect of repeatedly using an absorption solution of a strong base alkali component obtained by electrolysis to obtain an absorption solution, and repeatedly removing acidic harmful gases by the principle of neutralization reaction of acid and alkali.

The absorption solution does not discharge from the circulation line at all, and has the effect of recycling the absorbent and effectively using it as a by-product. ,

By-products 1) By-products obtained from chlorine gas (Cl ₂ ) and hydrogen gas (H ₂ ) by-product raw materials generated by electrolysis of salt (absorbent principle). Hydrochloric acid, 2. Effective use of sodium hypochlorite etc.

The by-product 2) is composed of SO ₂ and CO ₂ during thermal decomposition.
By-products obtained from by-product raw materials; 1. SO ₂ raw material;
_{Sulfate, (H 2 SO 4),} 3. Sodium sulfite (Na ₂
SO ₃ ) 4. Sodium sulfate, 5. Effective use of by-products such as sodium nitrate.

By-product 3) Harmful gas SOx, N in exhaust gas
After removing Ox and CO ₂ , 95% denitration was performed with a pretreated activated carbon catalyst, and the residual CO ₂ was absorbed into a (second absorbent) sodium hydroxide solution raw material, turned into a saturated solution, and heated, and sodium carbonate (N
a ₂ CO ₃₎ products enable Benefits and CO ₂ byproducts effective use by able help us CO ₂ reduction of global warming.

[0048]

[Table 1] Economic comparison table of absorbents

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the use of an absorbent, a recycled absorbent and a by-product recovery structure.

[Explanation of symbols]

Reference Signs List 1 (first absorbent material) salt (NaCl) 2 electrolysis 3 generated by electrolysis, chlorine gas (Cl ₂ ) 4 generated by electrolysis, hydrogen gas (H ₂ ) 5 (second absorbent) sodium hydroxide stock solution 6 initial Start-up absorption solution 7 By-product solution raw material 8 Replenishment absorption solution 9 (Third absorbent) (Second absorbent) Adjust sodium hydroxide solution raw material to pH 13 Absorbent solution 10 (Fourth absorbent) SOx (90% ), NOx (15
%), CO ₂ (20%) rate simultaneous removal, generated synthetic compound or absorbent having a base pH of 5 to 6, 11 (fourth absorbent) Precipitated precipitate described above, 12 (fourth absorbent) Precipitated sodium bisulfite (N
aHSO ₃ ) 13 (fourth absorbent) Precipitated sodium bicarbonate (Na
The precipitate of HCO ₃ ) 14 (fourth absorbent) was thermally decomposed. 15 (fourth absorbent) sodium sulfite (Na ₂ SO ₃ )
And SO ₂ (by-product raw material) 16 (fourth absorbent) Sodium carbonate (Na ₂ CO ₃ ) and CO ₂ (absorbent raw material) 17 (fourth absorbent) The base alkali component having a pH of about 8.7 after thermal decomposition Generated synthetic compound or absorbent, regenerated circulating absorbent. 18 (fifth absorbent) absorption solution of strong base alkali component of pH 13.5 or more obtained by electrolysis or recycle circulation absorption solution 19 (sixth absorber) strong base alkali component of pH 13.5 or more obtained by electrolysis Absorption solution or regenerated circulating absorption solution adjusted to around pH 20 20 by-product 1) (first absorbent material) All by-products during electrolysis of salt (NaCl) 21 by-product, hydrochloric acid (HCl) 22 by-product, sodium hypochlorite (NaClO) 23 By-product, regenerated raw material for salt (NaCl) electrolysis 24 By-product 2) Overall by-product during thermal decomposition 25 By-product, SO ₂ 26 by-product, sulfuric acid (H ₂ SO ₄ ) 27 By-product, sodium sulfite (Na ₂ SO ₃₎ ) 28 by-product, sodium sulfate (Na ₂ SO ₄ ) 29 by-product, sodium nitrate (Na ₂ NO ₃ ) 30 by-product 3) Residual CO in exhaust gas ₂ Recovery 31 By-product, sodium carbonate (Na ₂ CO ₃ )

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D002 AA02 AA09 AA12 BA02 BA08 BA12 CA06 CA07 DA02 DA12 DA13 DA57 DA66 EA02 EA07 EA08 EA11 EA13 EA14 GA01 GA03 GB09 HA01 4D020 AA03 AA05 AA06 BA01 BA08 BA09 BA03 BC03 BC03 CC02 CC20 CD04 DA01 DA03 DB08

Claims (10)

[Claims] 1. SOx (90%) in combustion exhaust gas, NO
x (15%), CO ₂ (20%) removal rate, regenerated circulating absorbent, electrolysis of salt (NaCl) solution (first absorbent raw material) classified into the process of absorbent, sodium hydroxide solution (NaOH) (second absorbent), the use of sodium hydroxide solution is as follows: 1) use of absorbent solution adjusted to around pH 13 at the start-up of initial operation of (third absorbent) 2) by-product 3) A method of using an absorbent, characterized in that it is used for the use of a recycled circulating absorption solution at the time of circulating recycling and a use of a replenishing absorbing solution. 2. SOx, NOx, CO _{2 in} combustion exhaust gas
The (third absorbent) that classifies the absorption process of the removal and regeneration circulating absorbent is a sodium hydroxide solution (Na) of (second absorbent).
OH) in (a), and the recycled circulation absorption solution was adjusted to around pH 13 in the absorption solution use circulation process in (b).
%), NOx (15%), and CO ₂ (20%) in gas-liquid contact, and are simultaneously removed and absorbed in an absorbing solution by a neutralization reaction of acid and alkali. 3. SOx, NOx, CO _{2 in} flue gas
The removal process of the circulating absorbent is classified into (fourth absorbent): (third absorbent) (a) or (b), a harmful gas is removed, and the product compound absorbed in the absorption solution, sodium bisulfite (NaHSO ₃ ) + sodium bicarbonate (NaH
Neutral salt / weak base such as sodium sulfate (Na ₂ SO ₄ ) generated by gas-liquid contact between CO ₃ ) + sodium nitrate (NaNO ₃ ) and O _{2 in} exhaust gas, and synthesis was performed at pH 5-6. A method of using an absorbent, characterized in that a compound can be separated in the process of circulating and used to separate an absorbed solution and a separated product. 4. SOx, NOx, CO _{2 in} flue gas
Classification of the absorption process of the removal and regeneration circulating absorbent (fifth absorbent) is as follows.
SO ₂ (by-product raw material) that undergoes thermal decomposition in the 200 ° C. range
+ CO ₂ (absorbent raw material) and sodium sulfite (Na ₂
SO ₃ ) + sodium carbonate (Na ₂ CO ₃ ) + sodium nitrate (NaNO ₃ ) + sodium sulfate (Na ₂ S)
The base alkali component of O ₄ ) having a pH of about 8.7 can provide a regenerated circulating absorbent of the generated synthetic compound. It is obtained by thermal decomposition. SO ₂ (by-product raw material) + CO ₂ (absorbent raw material) is a by-product. The method of using an absorbent, characterized in that it is used effectively as a raw material for the absorbent. 5. SOx, NOx, CO _{2 in} flue gas
The (sixth absorbent) classified by the absorption process of the removal and regeneration circulating absorbent was a basic alkali component of the recycled circulation absorbent obtained by thermal decomposition of the (fifth absorbent), with a pH of around 8.7. hydroxide ions OH synthesized compound electrolysis ^- is replace, the electropolished in regeneration recycle absorbent solution of the average pH13.5 more strongly alkaline components, sodium nitrate (NaNO
₃ ) A neutral compound such as sodium sulfate (Na ₂ SO ₄ ), which has a low degree of ionization and is hardly decomposed, is also subjected to electrolysis.
A method of utilizing an absorbent by electrolysis, characterized by effectively utilizing a strongly basic alkali component obtained by electrolysis for a regenerated circulating absorption solution, whereby a regenerated circulating absorption solution having a pH of about 13.7 can be obtained. . 6. SOx, NOx, CO _{2 in} flue gas
The absorption process of the removed and regenerated circulating absorbent was classified (seventh absorbent).
The absorption solution of an alkali component having a strong base of 5 or more is adjusted to a pH of about 13, and SOx (90%), NOx, (15%) C
A method of use characterized by removing at an O ₂ (20%) rate, absorbing into a recycle / circulation absorbing solution by a neutralization reaction, repeatedly using the recycle / circulation recycle, and effectively using the absorbent. 7. The absorption reaction scale loss when the primary and initial operation start-up (third absorbent) and the secondary and regenerated recycle absorbent solution (seventh absorbent) are repeatedly used during recycle recycle, and The amount of loss of the absorbent during thermal decomposition and electrolysis is supplemented with (third absorbent) sodium hydroxide solution (NaOH) adjusted to pH around 13, and repeatedly used for recycling.
SOx (90%), NOx (15%), CO in exhaust gas
₂ Remove the (20%) rate, absorb the harmful gas after the neutralization reaction, do not discharge the harmful gas to the outside at all, use recycling and recycling, make it a recycling and absorbing solution, and use it repeatedly. How to use the absorbent which is characterized. 8. By-products 1) By-product raw materials generated during electrolysis of salt (absorbent raw material) and chlorine gas (Cl
₂ ), the hydrogen gas (H ₂ ) generated on the cathode is compound-heated,
After burning hydrogen gas and synthesizing it into hydrogen chloride (HCl), the chlorine gas is absorbed into hydrochloric acid as a by-product and into sodium hydroxide solution (NaOH) (second absorbent) in the initial salt solution electrolysis, and salt (NaCl) electrolysis is performed. A method for utilizing by-products of an absorbent, characterized by effectively utilizing by-products (industrial chemicals) such as recycled raw materials and sodium hypochlorite solution for industrial recycling. 9. By-product 2) SOx, NOx,
The product compound absorbed in the absorbing solution in the CO ₂ removal and neutralization reaction, sodium bisulfite (NaHSO ₃ ) + sodium hydrogen carbonate (NaHCO ₃ ) + sodium nitrate (NaN
O ₃ ) + sodium sulfate (Na ₂ SO ₄ ) produced by heating and decomposing the resulting precipitate of the synthetic compound.
₂ (By-product raw material) After oxidizing to SO ₃ with a vanadium pentoxide (V ₂ O ₅ ) catalyst that generates gas, sulfuric acid (H ₂ S
O ₄ ) by-product, or electrolysis of initial salt solution (second absorbent)
CO ₂ (absorbent raw material) coexisting with high-concentration SO ₂ is introduced into a sodium hydroxide solution (NaOH) to make a saturated solution,
Sodium sulfite (Na ₂ SO ₃ ) by-product, sodium hydroxide solution (NaOH) having absorbed CO ₂ was made into a saturated solution, and sodium hydrogen carbonate (NaHCO ₃ ) was heated to produce sodium carbonate (Na ₂ CO ₃ ) (sorbent raw material). ) A method of use characterized in that by-products are used effectively as absorbents, and by-products are used as industrial chemicals for industrial recycling. 10. By-product 3) Residual CO in combustion exhaust gas
₂ was subjected to a pretreatment with an activated carbon catalyst after desulfurization to reduce NOx to 9
5% denitration, absorption of sodium hydroxide solution (NaOH) in the (second absorbent) sodium hydroxide solution of the initial salt solution electrolysis, and heating of the saturated solution of sodium hydrogen carbonate (NaHCO ₃ ) to sodium carbonate (Na ₂ CO ₃ ). A method characterized by effectively utilizing CO ₂ in exhaust gas for by-products (industrial chemicals) for industrial recycling.