WO2006051650A1

WO2006051650A1 - Apparatus and method for removing mercury

Info

Publication number: WO2006051650A1
Application number: PCT/JP2005/017156
Authority: WO
Inventors: Hiroyuki Akiho; Shigeo Ito; Takashi Kiga; Noriyuki Iiyama; Kenji Takano
Original assignee: Central Research Institute Of Electric Power Industry; Ishikawajima-Harima Heavy Industries Co., Ltd.
Priority date: 2004-11-15
Filing date: 2005-09-16
Publication date: 2006-05-18
Also published as: JP2006136856A

Abstract

A method for separating and removing a zero-valent mercury gas from a gas to be treated, which comprises contacting an aqueous solution having a pH of about 1 or less and containing a mercury-oxidizing agent having a tri-valent iron Fe3+ as a component with the gas to be treated, to thereby convert the zero-valent mercury gas to a di-valent mercury gas and simultaneously dissolve it into the aqueous solution. The above method allows the separation and removal of a zero-valent mercury gas from a gas to be treated with a satisfactory removal percentage while suppressing the amount of the mercury-oxidizing agent to be used.

Description

Specification

Mercury removal apparatus and method

Technical field

[0001] The present invention relates to a mercury removal apparatus and method.

Background art

[0002] For example, Japanese Patent Application Laid-Open No. 10-216476 discloses several exhaust gas treatment apparatus powers S for removing zero-valent mercury Hg in exhaust gas, which is an object to be treated. Among the exhaust gas treatment devices described in JP-A-10-216476, the exhaust gas treatment device shown in FIG. 3 is an exhaust gas treatment device equipped with a two-column wet desulfurization device comprising a cooling tower and an absorption tower. In the equipment, mercury removal agents such as sodium hypochlorite, copper chloride, manganese chloride, iron chloride, chelating agent, coal ash, etc. are added to the circulating water of the cooling tower placed in the previous stage, so that This product converts and removes the mercury Hg ^G into water-soluble divalent mercury Hg ²⁺ .

Patent Document 1: Japanese Patent Laid-Open No. 10-216476

Disclosure of the invention

Problems to be solved by the invention

[0003] Incidentally, the exhaust gas treatment apparatus of Patent Document 1 has the following problems.

(1) When the above mercury removing agent is added to low pH circulating water, the mercury removing agent decomposes at a strong rate, so it is necessary to add a large amount of mercury removing agent.

(2) Mercury removal when sulfur dioxide SO is contained in the exhaust gas to be treated

2

Since the agent reacts with sulfur dioxide so that it is consumed, a large amount of mercury removing agent is still used.

2

It is necessary to add.

[0004] The present invention has been made in view of the above-described circumstances, and aims to suppress and reduce the amount of mercury oxidant used and to separate and remove zero-valent mercury gas at a sufficient removal rate for the gas to be processed. It is a life.

Means for solving the problem

[0005] In order to achieve the above object, according to the present invention, as a first solution for the mercury removal apparatus, zero-valent mercury gas is converted into water-soluble divalent mercury gas and separated from the gas to be treated. The apparatus for removal comprises a reaction separation means for bringing an aqueous solution containing a mercury oxidant ^composed of trivalent iron Fe ³⁺ and having a pH of about 1 or less into contact with the gas to be treated. Adopt means.

[0006] As a second solving means relating to the mercury removing apparatus, in the first means, the reaction separating means includes a nozzle for spraying an aqueous solution onto the gas to be treated, and after contacting the gas to be treated by the nozzle. A recovery container for recovering the aqueous solution of the aqueous solution, a circulation pump for supplying the aqueous solution recovered in the recovery container to the nozzle, a mercury oxidant addition device for adding a mercury oxidant to the aqueous solution, and the recovery container A pH meter that measures the pH of the aqueous solution, and a pH adjuster addition unit that adds a pH adjuster to the aqueous solution so that the pH of the aqueous solution sprayed from the nozzle is 1 or less based on the measurement result of the pH meter T ヽぅ The solution method is adopted.

[0007] As a third solution relating to the mercury removing apparatus, in the second means, the nozzle, the recovery container, and the circulation pump constitute a cooling tower arranged in the preceding stage in the two-column type wet desulfurization apparatus. The reaction separation means adopts the solution means that the cooling tower is configured with a pH measuring device, a pH adjuster addition unit, and a mercury oxidizer addition device.

[0008] As a fourth means for solving the mercury removal apparatus, in any one of the above first to third means, the mercury oxidizing agent is iron chloride FeCl containing iron Fe ³⁺ as a component. Sampling

Three

Use.

[0009] As a fifth solution relating to the mercury removing apparatus, any one of the above first to fourth means is adopted. If the pH adjuster is hydrochloric acid HC1, the solution is adopted. As a sixth solving means relating to the mercury removing apparatus, the above-described solving means is adopted in which any one of the above first to fifth means is that the gas to be treated is combustion exhaust gas from a combustion furnace.

[0010] On the other hand, in the present invention, as a first solution for the mercury removal method, a method of converting zero-valent mercury gas into water-soluble divalent mercury gas and separating it from the gas to be treated is removed. The zero-valent mercury gas is converted to the divalent mercury gas by contacting an aqueous solution containing a mercury oxidizer containing trivalent iron Fe ³⁺ and having a pH of about 1 or less with the gas to be treated. At the same time, a solution is adopted that is dissolved in an aqueous solution and separated and removed from the gas to be treated.

[0011] As a second solution for the mercury removal method, in the first means, a pH adjuster and a mercury oxidant for reducing the pH to about 1 or less are used in a two-stage wet desulfurization apparatus. A solution is adopted in which zero-valent mercury gas is separated and removed from the gas to be treated by adding it to the washing water or circulating water of the cooling tower.

[0012] As a third solution for the mercury removal method, in the first or second method described above, a solution is used in which the mercury oxidizer is iron chloride FeCl containing trivalent iron Fe ³⁺ as a component.

Three

Use.

[0013] As a fourth solution for the mercury removal method, any one of the above first to third methods is adopted. If the pH adjuster is hydrochloric acid HC1, the solution is adopted.

[0014] As a fifth solution relating to the mercury removal method, any one of the above first to fourth means is adopted. If the gas to be treated is combustion exhaust gas from a combustion furnace, the solution is adopted. . The invention's effect

[0015] According to the present invention, the zero-valent mercury gas is divalent mercury by bringing an aqueous solution of a mercury oxidizing agent containing trivalent iron Fe ³⁺ into a pH 1 or lower and bringing it into gas-liquid contact with the gas to be treated. Since it is converted into a gas and dissolved in an aqueous solution and separated from the gas to be treated, zero-valent mercury gas can be separated from the gas to be treated with a sufficient removal rate while suppressing the amount of mercury oxidizing agent used.

Brief Description of Drawings

FIG. 1 is a system diagram of an exhaust gas treatment apparatus to which a mercury removal apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a detailed configuration of a mercury removing apparatus according to an embodiment of the present invention.

FIG. 3 is an experimental result showing the effectiveness of using trivalent iron Fe ³⁺ as a component as a mercury oxidizing agent in an embodiment of the present invention.

FIG. 4 is an experimental result showing the effect of pH on the Hg capture rate when using iron chloride FeCl having excellent oxidation performance against zero-valent mercury Hg according to an embodiment of the present invention. is there.

FIG. 5 is an experimental result showing the dependence of the Hg ^G trapping rate on the concentration of trivalent iron Fe ³⁺ in one embodiment of the present invention.

[FIG. 6] In one embodiment of the present invention, simulation according to the circulation rate of an aqueous solution of salted pig iron FeCl

Three

Hg of combustion exhaust gas. It is an experimental result which shows a removal rate.

FIG. 7 is an experimental result showing the influence of gas-liquid contact on the simulated combustion exhaust gas in one embodiment of the present invention.

Explanation of symbols

[0017] 1 boiler

2 Denitration equipment

Su V Shin

4 Two-column desulfurization equipment

5 Chimney

6 Tower body (collection container)

7 Spray nozzle

8 Circulation pump

9 pH meter

10 pH adjuster addition device

11 Mercury oxidizer addition equipment

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of an exhaust gas treatment apparatus to which the mercury removal apparatus according to this embodiment is applied. As shown in this figure, this exhaust gas treatment device is composed of a boiler 1, a denitration device 2, an electric dust collector 3, a two-column desulfurization device 4 and a chimney 5. The boiler 1 is for generating steam for power generation at, for example, a thermal power plant, and generates steam using oil, natural gas, coal, or the like as fuel. Exhaust gas generated by burning such fuel in the boiler 1 is supplied from the boiler 1 to the denitration device 2.

[0019] The denitration apparatus 2 removes nitrogen oxides NOx contained in the exhaust gas. This The denitrification apparatus 2 decomposes nitrogen oxides NOx into nitrogen N and water HO, for example, by causing ammonia to act on exhaust gas in the presence of a catalyst. The electric dust collector 3 is

twenty two

The dust contained in the exhaust gas is adsorbed and removed by the electric field. The double tower type desulfurization apparatus 4 is a double tower type wet desulfurization apparatus that wet-removes sulfur oxide SOx contained in the exhaust gas, and as shown in the drawing, the cooling tower 4A arranged in the preceding stage and the absorption arranged in the latter stage. It is composed of power with Tower 4B.

[0020] The cooling tower 4A has both a function of cooling the exhaust gas using circulating water and a function as a mercury removing apparatus according to the present embodiment. Here, since the cooling tower in a general two-column desulfurization apparatus aims at cooling and dust removal of exhaust gas, the circulating water is general water, but the circulating water W in this embodiment cools and removes the exhaust gas. In addition to the function, it is necessary to have the function of oxidizing the zero-valent mercury (Hg °) gas contained in the exhaust gas into the water-soluble divalent mercury (Hg ²⁺ ) gas. This is an aqueous solution containing a mercury oxidizer containing iron Fe ³⁺ as a component.

[0021] The use of such an aqueous solution as the circulating water W is one of the features of this embodiment. The mercury oxidizer is preferably salted pig iron FeCl, but contains trivalent iron Fe ³⁺ as a component.

Three

However, the present invention is not limited to this. Instead of the circulating water w, the washing water for the cooling tower 4A may be an aqueous solution containing a mercury oxidizing agent.

FIG. 2 is a block diagram showing a detailed configuration of the cooling tower 4A, that is, the mercury removing apparatus according to the present embodiment. As shown in Fig. 2, this mercury removal device is composed of a tower body 6 (collection container), a spray nozzle 7, a circulation pump 8, a pH meter 9, a pH adjuster addition device 10, a mercury oxidant addition device 11 Isometric composition. The tower body 6 is, for example, a hollow cylindrical container. A spray nozzle 7 that injects the circulating water downwards in the upper part of the tower, and a sealed structure that receives and collects the circulating water in the lower part of the inside. It has become. This mercury removal device has the essential components for a cooling tower, that is, the main body 6, the spray nozzle 7 and the circulation pump 8. Agent addition device 10 and mercury oxidant addition device 11 are added.

[0023] Further, an exhaust gas inlet 6a is provided at the side of the tower body 6, and a treated gas outlet 6b is provided at the upper part. The exhaust gas taken into the tower body 6 from the inlet 6a The circulating water injected from the swell 7 moves upward while making gas-liquid contact, and is discharged to the outside of the tower main body 6 as a treated gas. The spray nozzle 7 is arranged with a spread at the upper part in the tower body 6 so that the circulating water is in uniform gas-liquid contact with the exhaust gas in a wide area in the tower body 6.

The circulation pump 8 pumps out the circulating water accumulated in the lower part of the tower body 6 and supplies it to the spray nozzle 7. When the circulating pump 8 is continuously operated with respect to the exhaust gas that is continuously supplied into the tower body 6 due to the continuous operation of the thermal power plant, the circulating water is sequentially supplied from the spray nozzle 7 to the exhaust gas. Injected, gas-liquid contact between exhaust gas and circulating water is continuously performed.

The pH measuring device 9 is provided between the circulation pump 8 and the spray nozzle 7. The pH measuring device 9 measures the pH value of the circulating water supplied from the circulation pump 8 to the spray nozzle 7, that is, the circulating water injected into the exhaust gas, and outputs the pH value to the pH adjuster adding device 10 as pH information. The pH adjuster addition device 10 supplies the pH adjuster to the circulating water so that the pH value of the circulating water measured by the pH meter 9 is maintained at about 1 or less. This pH adjuster is preferably HC1 hydrochloride. For example, sulfuric acid HSO lowers the removal performance of zero-valent mercury gas.

twenty four

This is not preferable. Mercury oxidizer addition device 11 can be used for example,

It is supplied to the circulating water as 3 agents.

On the other hand, the absorption tower 4B is for removing the oxalic acid SOx from the treated gas discharged from the cooling tower 4A (that is, the mercury removing device). The absorption tower 4B separates the oxalic acid SOx as gypsum Ca SO into the absorption liquid by reacting the exhaust gas with an absorption liquid containing, for example, lime slurry. The chimney 5 has an absorption tower 4B, that is, a two-column desulfurization device 4

Four

The exhaust gas exhausted from the power is released to the high air outside.

[0027] Next, the action and effect of the mercury removing apparatus configured as described above will be described with reference to experimental data shown in Figs.

[0028] Fig. 3 shows experimental results showing the effectiveness of using a trivalent iron Fe ³⁺ component as a mercury oxidant. More specifically, salty iron-iron FeCl containing trivalent iron Fe ³⁺ as a component, iron chloride FeCl containing divalent iron Fe ²⁺ as a component, tetravalent titanium Ti used in this embodiment. ⁴⁺

3 2

Salt-titanium TiCl as a component, Trivalent titanium Ti3 ⁺ Salt-titanium TiCl as a component, Trivalent titanium Aluminum ³ Aluminum A1C1 with Al ³⁺ as component, and phosphoric acid HP with pentavalent phosphorus P ⁵⁺ as component

3 2

Prepare an aqueous solution containing O, and add a mixture of zero-valent mercury (Hg) gas and nitrogen (N) gas.

4 2

This shows the capture rate of zero-valent mercury Hg ^G when gas-liquid contact is made. In this experiment, the concentration of the target components (Fe ³⁺ , Fe ²⁺ , Ti ⁴⁺ , Ti ³⁺ , Al ³⁺ , P ⁵⁺ ) was adjusted to 100 ppm, and the pH of each aqueous solution was obtained by caloring hydrochloric acid HC1. Was adjusted to about 1.

[0029] As is clear from this experimental result, the aqueous solution of salty iron FeCl containing trivalent iron Fe ³⁺ as a component.

Although the 3rd liquid shows a high Hg ^G trapping rate, it repels salted iron iron FeCl containing divalent iron Fe2 ^+.

The other 2 aqueous solutions show very low Hg ^G trapping rate. Trivalent iron Fe ³⁺ is zero-valent mercury Hg. Against acidity, that is, zero-valent mercury Hg. The force electron acceptor to the ability to divalent mercury Hg ² + very high than the other components of interest! I understand that it is a trap.

FIG. 4 is an experimental result showing the influence of pH on the Hg trapping rate when iron chloride FeCl having excellent oxidation performance against zero-valent mercury Hg ° as described above is used.

Three

In this experiment, the concentration of trivalent iron Fe ³⁺ in the aqueous solution of iron chloride FeCl was lOOppm.

Three

The pH was adjusted by keeping it constant and adding HC1 hydrochloric acid.

[0031] This experimental result shows that when the pH of an aqueous solution of salted pig iron FeCl drops to around 1, Hg ^G trapping

Three

As the rate increases rapidly, the Hg capture rate hardly increases even when the chlorine C1 concentration, that is, the amount of HC1 added, is increased in the region below pHl. Therefore, the amount of salty pig iron FeCl used as the mercury oxidizer is minimized, and a high Hg capture rate is obtained.

Three

For this purpose, it can be seen that it is preferable to set the pH to about 1 or less, preferably about 1 or less.

[0032] Next, FIG. 5 is an experimental result showing the dependence of the Hg ^G trapping rate on the concentration of trivalent iron Fe ³⁺ . In this experiment, the and when set to approximately 2.5 to pH without added Caro and hydrochloric acid when the pH is set to 1 or less by adding hydrochloric acid, trivalent iron concentration Fe ³⁺ (Fe ^{3 +} 5 μg / m ³ N of zero-valent mercury (Hg ^G ) gas and nitrogen (N) gas

2

The Hg capture rate was measured by circulating a mixed gas.

[0033] The experimental results force to Bunryokuru so, if: PHL, trivalent iron Fe ³⁺ concentration our relatively low Vヽregion (approximately 50ppm neighboring region), on 3-valent iron Fe ³⁺ As the concentration increases, the Hg ^G trapping rate increases rapidly, and in the region where the trivalent iron Fe ³⁺ concentration is about lOOppm or more, the Hg trapping rate is It rises relatively slowly. On the other hand, when the pH is about 2.5, the Hg trapping rate increases with a substantially constant slope with respect to the increase of the trivalent iron Fe ³⁺ concentration, but the pH is 1 or less. Compared with, Hg capture rate is low. Therefore, in a region where the concentration of trivalent iron Fe ³⁺ is relatively low, that is, in a state where the amount of iron chloride FeCl used as a mercury oxidizer is minimized,

Three

It can be seen that it is preferable to set _PH to about 1 or less in order to obtain a high Hg capture rate.

[0034] The experimental results shown in Fig. 3 to Fig. 5 show that the composition of the components differs from the exhaust gas discharged from the boiler 1 of the actual thermal power plant, that is, zero-valent mercury (Hg) gas and nitrogen (N) gas. Mixed gas

2

It is about. On the other hand, the experimental results shown in FIGS. 6 and 7 show that Hg related to simulated combustion exhaust gas having substantially the same composition as the exhaust gas of boiler 1 containing nitrogen oxides N Ox and sulfur oxides SOx. . Show the removal rate.

[0035] In Fig. 6, a counter-current spray type wet scrubber having the same configuration as the cooling tower 4A described above is used, and the circulation rate of the aqueous solution of iron chloride FeCl as the circulating water is 2 lZmin, 4 lZmin or 5 lZmi.

Three

The Hg removal rate of the simulated combustion exhaust gas when switching to n is shown. According to the results of this experiment, it was confirmed that the simulated combustion exhaust gas having substantially the same composition as the exhaust gas of boiler 1 can achieve a Hg removal rate of nearly 80% regardless of the circulation amount. It was done.

FIG. 7 shows Experimental Examples 1 and 2 regarding the influence of gas-liquid contact on the simulated combustion exhaust gas. In this experiment, each was filled with 100 ml of absorption liquid (aqueous solution of salted iron iron FeCl).

Three

In addition, prepare multiple containers (impinger) for publishing simulated combustion exhaust gas, and the amount of absorbed liquid when publishing simulated combustion exhaust gas with one impinger is 100 ml, and simulated combustion exhaust gas is connected with three impingers connected in series. The Hg removal rate was measured when the amount of liquid absorbed was 300 ml, and the amount of liquid absorbed was 500 ml when publishing simulated combustion exhaust gas with five impingers connected in series. Experimental example 1 shows the case where the concentration of trivalent iron Fe ³⁺ is lOOppm, and Experimental example 2 shows the case where the concentration of trivalent iron Fe ³⁺ is 400 ppm.

[0037] That is, in this experiment, the absorption liquid volume of 100 ml indicates the number of publishing times, the absorption liquid volume of 300 ml indicates the publishing frequency of 3, and the absorption liquid volume of 500 ml indicates the publishing frequency of 5 times. According to the results of this experiment, the number of publishing times, that is, simulated combustion exhaust gas Hg removal rate increases as the number of gas-liquid contact between the liquid and the absorbent (iron chloride FeCl aqueous solution) increases.

Three

It was confirmed to rise. In this experiment, it was confirmed that an Hg ^G removal rate of over 80% was obtained with 5 publishings.

[0038] The experimental results in Fig. 7 show that the number of contact with the simulated combustion exhaust gas and the gas-liquid greatly affects the Hg ° removal rate, but this gas-liquid contact state is improved. Therefore, it is extremely important to increase the contact area and the contact time. Therefore, by devising the shape of the spray nozzle 7 and the tower main body 6 or the exhaust gas passage method in the tower main body 6, the contact area and the contact time are increased, and the zero-valent mercury (Hg) gas removal rate is increased. It is important to improve.

[0039] According to the present embodiment, salted pig iron FeCl containing trivalent iron Fe ³⁺ as a component is converted to mercury acid.

3) An aqueous solution that is contained as a soot agent and that has a pH set to about 1 or less by adding a pH adjuster such as hydrochloric acid HC1 is gas-liquid contacted with the gas to be treated such as the exhaust gas (combustion exhaust gas) of boiler 1. By touching, it is possible to remove the zero-valent mercury (Hg) gas at a high removal rate while keeping the addition amount (use amount) of the mercury oxidizing agent as small as possible.

[0040] In addition, this mercury removal apparatus is an essential component for the cooling tower, that is, a component for adding a function as a mercury removal apparatus to the tower body 6, the spray nozzle 7 and the circulation pump 8, ie, pH. A measuring instrument 9, a pH adjuster addition device 10 and a mercury oxidant addition device 11 are added. Therefore, by adding a pH meter 9, pH adjuster addition device 10 and mercury oxidizer addition device 11 to an existing thermal power plant, a zero-valent mercury gas removal function can be realized. There are advantages to being able to introduce it easily.

[0041] It should be noted that the present invention is not limited to the above-described embodiment, and for example, the following modifications can be considered.

(1) Mercury oxidizer is not limited to iron chloride FeCl. It is a compound containing trivalent iron Fe ³⁺ as a component.

Three

Others are acceptable as long as they are present.

(2) The pH adjuster is not limited to HC1 hydrochloric acid, but other ones may be used.

(3) The gas to be treated is not limited to the combustion exhaust gas of the combustion furnace of the boiler 1.

(4) The configuration of the mercury removal device is not limited to the above embodiment. ヽ. Any other configuration may be used as long as it can achieve good gas-liquid contact between the gas to be treated and the aqueous solution of the mercury oxidizing agent.

Claims

The scope of the claims

[1] A device that converts zero-valent mercury gas into water-soluble divalent mercury gas and separates it from the gas to be treated.

A mercury removing apparatus comprising a reaction separation means for bringing an aqueous solution containing a mercury oxidizing agent containing trivalent iron (Fe ³⁺⁾ and having a pH of about 1 or less into contact with the gas to be treated. .

[2] The reaction separation means is

A nozzle for spraying an aqueous solution onto the gas to be treated;

A recovery container for recovering the aqueous solution after contact with the gas to be treated by the nozzle; a circulation pump for supplying the aqueous solution recovered in the recovery container to the nozzle; and a mercury oxidant addition device for adding a mercury oxidant to the aqueous solution When,

A pH meter for measuring the pH of the aqueous solution recovered in the recovery container;

Based on the measurement result of the pH measuring device, a pH adjusting agent adding section for adding a pH adjusting agent to the aqueous solution so that the pH of the aqueous solution sprayed by the nozzle force is maintained at 1 or less.

The mercury removing apparatus according to claim 1, comprising:

[3] The nozzle, the recovery container, and the circulation pump constitute a cooling tower placed in the previous stage in a two-column wet desulfurization system, and the reaction separation means is connected to the cooling tower with a pH meter, pH ^3. The mercury removing apparatus according to claim ^2, further comprising a regulator adding unit and a mercury oxidizing agent adding device.

[4] The mercury oxidizer is a salty iron-iron FeCl containing trivalent iron Fe ³⁺ as a component.

Three

The mercury removing apparatus according to claim 1.

[5] The mercury oxidizer is salted iron iron FeCl containing trivalent iron Fe ³⁺ as a component.

Three

The mercury removing apparatus according to claim 2.

[6] The mercury oxidizing agent is a salty iron-iron FeCl containing trivalent iron Fe ³⁺ as a component.

Three

The mercury removing device according to claim 3.

[7] The mercury removing apparatus according to [2], wherein the pH adjuster is HC1 hydrochloric acid.

[8] The mercury removing apparatus according to [3], wherein the pH adjuster is HC1 hydrochloric acid.

[9] The mercury removing apparatus according to claim 4, wherein the pH adjusting agent is HC1 hydrochloric acid.

[10] The mercury removing apparatus according to claim 5, wherein the pH adjusting agent is HC1 hydrochloric acid.

[11] The mercury removing apparatus according to [6], wherein the pH adjusting agent is HC1 hydrochloric acid.

[12] The mercury according to claim 1, wherein the gas to be treated is combustion exhaust gas from a combustion furnace

13. The mercury removal apparatus according to claim 2, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

14. The mercury removal apparatus according to claim 3, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

15. The mercury removal apparatus according to claim 4, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

16. The mercury removal apparatus according to claim 5, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

17. The mercury removal apparatus according to claim 6, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

18. The mercury removal apparatus according to claim 7, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

19. The mercury removal apparatus according to claim 8, wherein the gas to be treated is a combustion exhaust gas from a combustion furnace.

20. The mercury removal apparatus according to claim 9, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

21. The water removal apparatus according to claim 10, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

[22] The water according to claim 11, wherein the gas to be treated is combustion exhaust gas from a combustion furnace

[23] A method of converting zero-valent mercury gas into water-soluble divalent mercury gas and separating it from the gas to be treated.

The zero-valent mercury gas is converted into divalent mercury gas by bringing an aqueous solution containing a mercury oxidant ^composed of trivalent iron Fe ³⁺ and having a pH of about 1 or less into contact with the gas to be treated. And dissolved in an aqueous solution and separated from the gas to be treated

A method for removing mercury.

The zero-value mercury gas is treated by adding a pH adjuster and mercury oxidizer to reduce the pH to about 1 or less to the washing water or circulating water of the cooling tower placed in the previous stage in a two-column wet desulfurization system. The method for removing mercury according to claim 23, wherein the mercury is separated and removed from the target gas.

The mercury oxidizer is a salty iron-iron FeCl containing trivalent iron Fe ³⁺ as a component.

Three

The method for removing mercury according to Claim 23.

Three

The method for removing mercury according to Claim 24.

25. The mercury removing method according to claim 24, wherein the pH adjuster is hydrochloric acid HC1. 26. The method for removing mercury according to claim 25, wherein the pH adjuster is hydrochloric acid HC1. 27. The mercury removing method according to claim 26, wherein the pH adjuster is HC1 hydrochloric acid. 24. The mercury removal method according to claim 23, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

25. The mercury removal method according to claim 24, wherein the treatment target gas is combustion exhaust gas from a combustion furnace.

26. The mercury removal method according to claim 25, wherein the gas to be treated is a combustion exhaust gas from a combustion furnace.

27. The mercury removal method according to claim 26, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

28. The mercury removal method according to claim 27, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

29. The mercury removal method according to claim 28, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.

30. The mercury removal method according to claim 29, wherein the gas to be treated is combustion exhaust gas from a combustion furnace.