Desulfurization tail gas treatment device

Abstract

The utility model discloses a desulfurization tail gas treatment device which comprises an ammonia washing tower, a primary alkaline washing tower connected with the ammonia washing tower, an acid washing tower connected with the primary alkaline washing tower, a secondary alkaline washing tower connected with the acid washing tower and a water washing tower connected with the secondary alkaline washing tower, and ammonia-containing liquid is added into the ammonia washing tower. The desulfurization tail gas treatment device disclosed by the utility model can be used for effectively treating hydrogen sulfide in tail gas, so that the environment-friendly requirement is met; through the front-section ammonia washing, the content of hydrogen sulfide in the tail gas is reduced, the consumption of sodium alkali treatment in the subsequent process is reduced, the cost is reduced, and the desulfurization tail gas treatment effect is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of biochemical waste gas treatment, and specifically relates to a desulfurization tail gas treatment device. Background Art

[0002] The technical background of the VOCs treatment device is: in the process of gas purification production, tail gas will be generated due to the flow and storage of various media. Chemical waste gas generally has single or multiple hazards such as flammability, explosiveness, and poisoning. Most of the substances are irritating, corrosive, and highly toxic, and even carcinogenic. These waste gases usually come from the gas discharged during the feeding of chemical product tanks and the transfer of materials between tanks or temperature changes. Since the gas composition is different in different processes, targeted treatment processes need to be adopted. For the above-mentioned exhaust gas, if the process production is in a closed process, it can be led back into the system. If more oxygen is mixed into the process production, a special VOCs treatment device is required for treatment.

[0003] At present, most coking enterprises use the HPF wet ammonia desulfurization process for coke oven gas purification and desulfurization. The sulfur in the gas is recovered through oxidation regeneration and sulfur melting. However, due to the characteristics of the process, the exhaust gas emitted during the whole process contains a large amount of hydrogen sulfide and ammonia. These gases are recovered to the exhaust gas treatment device through negative pressure or fans, and then the hydrogen sulfide content in the gas is brought to the process standard for combustible emissions through alkaline washing, and the ammonia in the exhaust gas is removed through acid washing.

[0004] The working principle of the alkaline washing tower is based on the acid-base neutralization principle. It generally treats chemical substances that are more easily soluble in water, and uses absorption liquids such as sodium hydroxide solution to purify and neutralize waste gas containing acidic gases. After the acid-base waste gas is led out from the air duct, it enters the waste gas neutralization treatment tower, flows upward to the filter material layer, and contacts and reacts with the neutralizing liquid sprayed from the nozzle. The absorbed waste gas continues to flow upward to the second filter material layer, contacts with the neutralizing liquid sprayed from the second-stage nozzle, and reacts with neutralization again, and then passes through the swirl plate or the fog capture layer to enter the next stage of purification. A certain amount of filler is added to the tower, so that the waste gas and the washing liquid can be fully contacted. The washing liquid flowing down from the tower is then lifted to the top of the tower by a delivery pump for spraying, and is continuously recycled. After the circulating washing liquid reaches a certain concentration, it is discharged to the sewage treatment station or desulfurization, ammonia distillation and other systems.

[0005] A large amount of waste gas will be generated during the coking production process, which contains a large amount of hydrogen sulfide. The conventional VOCs treatment process is acid washing - alkali washing - water washing - sending to the coke oven for combustion treatment or RTO device for incineration treatment. However, for the treatment of tail gas with high hydrogen sulfide content such as greater than 1g / l HFP wet desulfurization regeneration, after acid washing - alkali washing - water washing, there is still a high content of hydrogen sulfide in the tail gas. For the subsequent combustion treatment, the generation of sulfur dioxide will still increase, and at the same time, it will increase the possibility of corrosion to subsequent equipment.

[0006] For example, the patent document with publication number CN103566734A discloses a tail gas desulfurization treatment device, including a curved pipe connected to a chimney at one end, and a solution tank containing an alkaline solution at the other end of the curved pipe, an exhaust pipe is arranged above the solution tank, a drain pipe is arranged at the bottom, and the solution tank is connected to a water inlet pipe. One end of the curved pipe extends to the bottom of the solution tank. The solution tank is provided with a mixed solution of alkaline substance and water. The technical solution disclosed in the patent document also cannot solve the technical problems described above. Utility Model Content

[0007] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a desulfurization tail gas treatment device, the purpose of which is to improve the desulfurization tail gas treatment effect.

[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a desulfurization tail gas treatment device, including an ammonia washing tower, a primary alkali washing tower connected to the ammonia washing tower, an acid washing tower connected to the primary alkali washing tower, a secondary alkali washing tower connected to the acid washing tower and a water washing tower connected to the secondary alkali washing tower, and an ammonia-containing liquid is added to the ammonia washing tower.

[0009] The ammonia washing tower is connected to an ammonia washing pump, and the ammonia washing pump delivers the ammonia-containing liquid into the ammonia washing tower.

[0010] The primary alkali washing tower is connected to a primary alkali washing pump, and the primary alkali washing pump delivers the sodium hydroxide solution into the primary alkali washing pump.

[0011] A secondary mist catching layer is arranged on the top of the primary alkali washing tower.

[0012] The pickling tower is connected to a pickling pump, and the pickling pump delivers a pickling solution containing sulfuric acid into the pickling tower.

[0013] The secondary alkali washing tower is connected to a secondary alkali washing pump, and the secondary alkali washing pump delivers the sodium hydroxide solution into the secondary alkali washing pump.

[0014] A secondary acid mist collecting layer is arranged on the top of the pickling tower.

[0015] The water washing tower is connected to a water washing pump, and the water washing pump delivers production water or industrial water to the water washing tower.

[0016] The desulfurization tail gas treatment device of the utility model can effectively treat hydrogen sulfide in the tail gas, meeting the environmental protection needs; through the front-end ammonia washing, the hydrogen sulfide content in the tail gas is reduced, the consumption of sodium alkali in the subsequent process treatment is reduced, the cost is reduced, and the desulfurization tail gas treatment effect is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] This specification includes the following drawings, which show the following contents:

[0018] Figure 1 It is a structural schematic diagram of the desulfurization tail gas treatment device of the utility model;

[0019] The markings in the figure are: 1. Ammonia washing tower; 2. Primary alkali washing tower; 3. Acid washing tower; 4. Secondary alkali washing tower; 5. Water washing tower; 6. Ammonia washing pump; 7. Primary alkali washing pump; 8. Acid washing pump; 9. Secondary alkali washing pump; 10. Water washing pump; 11. Desulfurization section; 12. Ammonia evaporation section; 13. Ammonium sulfate section; 14. Sewage treatment section. DETAILED DESCRIPTION

[0020] The specific implementation methods of the utility model are further explained in detail below with reference to the accompanying drawings through the description of embodiments, with the aim of helping technicians in the field to have a more complete, accurate and in-depth understanding of the concept and technical solution of the utility model and facilitating its implementation.

[0021] like Figure 1 As shown, the utility model provides a desulfurization tail gas treatment device, including an ammonia washing tower 1, a primary alkali washing tower 2 connected to the ammonia washing tower 1, an acid washing tower 3 connected to the primary alkali washing tower 2, a secondary alkali washing tower 4 connected to the acid washing tower 3 and a water washing tower 5 connected to the secondary alkali washing tower 4, and an ammonia-containing liquid is added to the ammonia washing tower 1.

[0022] Specifically, if Figure 1 As shown, in the utility model, by adopting the process of ammonia liquid washing - alkali washing - acid washing - alkali washing - water washing, that is, first using ammonia-containing liquid as an alkali source, the acidic components in the tail gas, especially hydrogen sulfide, will form ammonium sulfide salts with ammonia. During the circulation process, the high-concentration washing liquid can be sent to the desulfurization system for treatment and recycling, thereby reducing the environmental loss of waste liquid purification. At the same time, no sodium salt will be added to the ammonia desulfurization system. Secondly, the waste liquid of sodium hydroxide alkali washing will be discharged to ammonia evaporation and reused as waste alkali liquid, reducing the loss of alkali liquid. After that, the organic matter in the waste alkali liquid is evaporated by ammonia evaporation, which is conducive to reducing the amount of wastewater entering the sewage treatment system and reducing the treatment cost. Thirdly, adding an alkali wash after acid washing helps to neutralize the acid mist entrained by the tail gas in the acid washing tower 3, thereby reducing the corrosion of the acid mist to the subsequent equipment pipelines.

[0023] For H2S content exceeding 1g / m 3The desulfurized tail gas adopts the process of ammonia washing - primary alkali washing - acid washing - secondary alkali washing - water washing - sending to the coke oven for combustion treatment, which is intended to remove more hydrogen sulfide in the initial treatment stage and reduce the impact of flue gas on the coke oven combustion emission indicators. At present, the alkali washing process uses sodium hydroxide as the alkali source and sulfuric acid as the acid source, in which the alkali washing tower and the water washing tower are both cyclic spraying. The desulfurized tail gas treatment device of the utility model can form a tail gas treatment process of washing with ammonia condensate produced by salt extraction - primary sodium hydroxide alkali washing - sulfuric acid washing - secondary sodium hydroxide alkali washing - water washing.

[0024] like Figure 1 As shown, the ammonia scrubber 1 is connected to the ammonia scrubber pump 6, and the ammonia scrubber pump 6 delivers the ammonia-containing liquid into the ammonia scrubber 1. The ammonia scrubber 1 uses the ammonia-containing condensate (also called concentrated (dilute) ammonia water) produced in the salt extraction section to scrub the tail gas and reduce the content of hydrogen sulfide in the tail gas to 0.8 g / m 3 The sulfur foam liquid entrained in the desulfurized tail gas is then washed off.

[0025] Preferably, the ammonia-containing condensate used in the ammonia scrubber 1 can be the concentrated (dilute) ammonia water produced in the HPF wet desulfurization and salt extraction section, which can be further utilized after being washed in the post-desulfurization mist collection tower.

[0026] like Figure 1 As shown, the ammonia wash pump 6 is connected to the top and the bottom of the ammonia wash tower 1 , and the ammonia wash pump 6 is also connected to the desulfurization section 11 .

[0027] The primary alkali washing tower uses sodium hydroxide liquid as the alkali source. The washing liquid containing ammonium sulfide produced after treatment in the ammonia washing tower 1 can be returned to the desulfurization system. The sodium hydroxide solution in the primary alkali washing tower ensures the quality of tail gas alkali washing, which can greatly reduce the loss of liquid alkali.

[0028] like Figure 1 As shown, the primary alkali washing tower 2 is connected to the primary alkali washing pump 7, and the primary alkali washing pump 7 delivers the sodium hydroxide solution to the primary alkali washing pump 7. A secondary mist catching layer is set on the top of the primary alkali washing tower to reduce the amount of alkali solution contained in the tail gas as much as possible, so as not to affect the quality of ammonium sulfate formed in the subsequent pickling process. The top of the ammonia washing tower 1 may not be provided with a mist catching layer, and the tail gas entrained liquid after washing enters the primary alkali washing tower and finally enters the ammonia distillation section 12, and is sent to biochemical treatment after ammonia distillation.

[0029] like Figure 1 As shown, the primary alkali washing pump 7 is connected to the top and the bottom of the primary alkali washing tower 2 , and the primary alkali washing pump 7 is also connected to the ammonia distillation section 12 .

[0030] The pickling tower 3 adopts the method of adding concentrated sulfuric acid to the washing liquid to keep the pH of the washing liquid between 3 and 5. A secondary acid mist trapping layer is set on the top of the pickling tower 3 to minimize the acid mist content in the tail gas brought into the rear section. The loss of alkali solution in the secondary alkali washing tower can be reduced. The pickling tower 3 is regularly discharged and sent to the ammonium sulfate section 13 as a raw material for producing ammonium sulfate.

[0031] like Figure 1 As shown, the pickling tower 3 is connected to the pickling pump 8, and the pickling pump 8 delivers sulfuric acid into the pickling tower 3. The pickling pump 8 is connected to the top and bottom of the pickling tower 3, and the pickling pump 8 is also connected to the ammonium sulfate section 13.

[0032] A secondary alkali washing tower is added after the acid washing tower 3 and before the water washing tower 5. Sodium hydroxide alkali washing is used as the secondary alkali washing to neutralize the acid mist brought out by the gas. The pH is maintained at 9-11 to reduce the acid mist contained in the subsequent tail gas to reduce the corrosion of equipment pipelines. At the same time, the hydrogen sulfide remaining in the tail gas can also be neutralized. A secondary fog collecting layer is set at the top of the secondary alkali washing section to capture the alkali solution entrained in the tail gas to reduce the amount of alkali solution entering the water washing section. At the same time, the alkali content in the water washing section will not be increased, and the impact on the quality of ammonium salt produced by ammonia desulfurization is reduced.

[0033] like Figure 1 As shown, the secondary alkali washing tower 4 is connected to the secondary alkali washing pump 9, and the secondary alkali washing pump 9 delivers the sodium hydroxide solution to the secondary alkali washing pump 9. The secondary alkali washing pump 9 is connected to the top and bottom of the secondary alkali washing tower 4, and the secondary alkali washing pump 9 is also connected to the ammonia distillation section 12.

[0034] The water washing tower 5 uses production water or industrial water for washing. The calcium hardness of the production water or industrial water is not more than 200mg / l. The washing water is replaced once a day and sent to the desulfurization system as supplementary water. After the above multi-tower continuous washing, the hydrogen sulfide in the desulfurized tail gas can be reduced to 50mg / m 3 The following requirements are met for combustion treatment.

[0035] like Figure 1 As shown, the water washing tower 5 is connected to a water washing pump 10, and the water washing pump 10 delivers production water or industrial water to the water washing tower 5. The water washing pump 10 is connected to the top and the bottom of the water washing tower 5.

[0036] Preferably, the alkali solution of the secondary alkali washing tower can be fresh alkali solution, and the waste alkali solution after washing can be discharged to the primary alkali washing tower for reuse to reduce the loss of alkali solution.

[0037] The desulfurization tail gas treatment device of the above structure has the following advantages:

[0038] 1. It can effectively treat hydrogen sulfide in tail gas and meet environmental protection needs.

[0039] 2. Through the front-end ammonia washing, the hydrogen sulfide content in the tail gas is reduced, the consumption of sodium alkali in the subsequent process is reduced, and the cost is reduced.

[0040] 3. The combined product of ammonia water and hydrogen sulfide can be returned to the desulfurization system for recovery, reducing the pressure on sewage treatment.

[0041] 4. Washing first uses ammonia-containing liquid as an alkali source. The acidic components in the tail gas, especially hydrogen sulfide, will form ammonium sulfide salts with ammonia. During the circulation process, the high-concentration washing liquid can be sent to the desulfurization system for treatment and recycling, reducing the environmental loss of waste liquid purification. At the same time, no sodium salt will be added to the ammonia desulfurization system. Moreover, the ammonia-containing condensate used in the ammonia washing tower 1 (section) can be the concentrated (dilute) ammonia water produced by salt extraction, which can be further utilized after washing in the mist collecting tower (section) after desulfurization, effectively reducing the amount of washing water and drainage.

[0042] 5. The waste liquid from alkaline washing with sodium hydroxide will be discharged to ammonia evaporation for reuse as waste alkali liquid, reducing the loss of alkali liquid. After that, the organic matter in the waste alkali liquid will be evaporated through ammonia evaporation, which is beneficial to reduce the amount of wastewater entering the sewage treatment system and reduce the treatment cost.

[0043] 6. Adding an alkaline wash after pickling helps to neutralize the acid mist carried out by the tail gas in the pickling tower 3, thereby reducing the corrosion of the acid mist to the subsequent equipment pipelines. At the same time, it can also neutralize the excessive hydrogen sulfide in the tail gas and reduce the discharge of hydrogen sulfide in the tail gas.

[0044] 7. Fresh alkali solution can be used for the secondary alkali washing tower (section), and the waste alkali solution after washing can be discharged to the primary alkali washing tower (section) for reuse to reduce the loss of alkali solution.

[0045] The above is an exemplary description of the utility model in conjunction with the accompanying drawings. Obviously, the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model; or the above concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A desulfurization tail gas treatment device, characterized in that: The invention comprises an ammonia washing tower, a primary alkali washing tower connected to the ammonia washing tower, an acid washing tower connected to the primary alkali washing tower, a secondary alkali washing tower connected to the acid washing tower and a water washing tower connected to the secondary alkali washing tower. Ammonia-containing liquid is added into the ammonia washing tower.

2. The desulfurization tail gas treatment device according to claim 1, characterized in that: The ammonia washing tower is connected to an ammonia washing pump, and the ammonia washing pump delivers the ammonia-containing liquid into the ammonia washing tower.

3. The desulfurization tail gas treatment device according to claim 1, characterized in that: The primary alkali washing tower is connected to a primary alkali washing pump, and the primary alkali washing pump delivers the sodium hydroxide solution into the primary alkali washing pump.

4. The desulfurization tail gas treatment device according to any one of claims 1 to 3, characterized in that: A secondary mist catching layer is arranged on the top of the primary alkali washing tower.

5. The desulfurization tail gas treatment device according to any one of claims 1 to 3, characterized in that: The pickling tower is connected to a pickling pump, and the pickling pump delivers a pickling solution containing sulfuric acid into the pickling tower.

6. The desulfurization tail gas treatment device according to any one of claims 1 to 3, characterized in that: The secondary alkali washing tower is connected to a secondary alkali washing pump, and the secondary alkali washing pump delivers the sodium hydroxide solution into the secondary alkali washing pump.

7. The desulfurization tail gas treatment device according to any one of claims 1 to 3, characterized in that: A secondary acid mist collecting layer is arranged on the top of the pickling tower.

8. The desulfurization tail gas treatment device according to any one of claims 1 to 3, characterized in that: The water washing tower is connected to a water washing pump, and the water washing pump delivers production water or industrial water to the water washing tower.

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