Desulfurization and thallium removal process purification system for thallium-containing flue gas
By adding dethallium agent and sodium carbonate to the flue gas desulfurization and dethallium process, the separation of gypsum and thallium compounds is achieved, solving the problem of high gypsum disposal cost in the prior art, and improving the economic and safety of the process.
Patent Information
- Application Number
- CN202510050205.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-05-30
AI Technical Summary
In the prior art, in the desulfurization and dethallium process, gypsum is mixed with thallium compounds, resulting in high cost of disposal of hazardous waste and difficult to separate the desulfurization and dethallium processes, affecting process efficiency.
By adding dethallium dethallium agent to the absorption tower system, the thallium compound in the sodium sulfate solution is first removed, and the sludge formed after dethallium is disposed of separately as hazardous waste. The remaining solution is used to form gypsum slurry, and sodium carbonate is added during the gypsum generation process to neutralize excess calcium hydroxide to reduce the risk of scaling.
The separation of flue gas desulfurization and dethallium solids is achieved, the cost of gypsum disposal is reduced, the safety and economics of the process are improved, and the gypsum can be comprehensively utilized.
Smart Images
Figure CN120054189A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of chemical processing, and in particular to a desulfurization and thallium removal process purification system for thallium-containing flue gas. More specifically, it relates to a process flow for separately generating thallium-removed hazardous waste and gypsum solid waste during the integrated desulfurization and thallium removal of thallium-containing flue gas, reducing the disposal cost of gypsum generated during the desulfurization of thallium-containing flue gas. Background Art
[0002] Thallium is one of the rare and dispersed elements widely distributed on the earth, existing in valence states of 0, +1, and +3. It is widely associated with minerals such as galena, sphalerite, chalcopyrite, pyrite, marcasite, coal, and rocks such as mica and feldspar. It is a highly toxic substance and one of the most toxic metal elements, with toxicity comparable to arsenic. Thallium compounds are one of the main hazardous wastes listed in the WHO's key restricted list and are also included in the list of pollutants that China gives priority to controlling and are incorporated into the appendix of the "Hazardous Waste Identification Standard - Identification of Toxic Substance Content".
[0003] During the smelting process in industries such as iron and steel and non-ferrous metals, the flue gas generated contains a certain amount of thallium and also a large amount of SO 2 , and during desulfurization, the thallium in the flue gas is also removed and enters the slurry together with SO 2 . If the conventional desulfurization and thallium removal process route is adopted, during the dehydration of gypsum, the thallium compound and gypsum are mixed together and become hazardous waste, which cannot be utilized as solid waste. Currently, the country has strict regulations on the disposal of hazardous waste, and the disposal cost of hazardous waste is relatively high. Finding a process route for separating thallium removal and desulfurization will greatly reduce the operating cost. Summary of the Invention
[0004] The purpose of the present invention is to achieve the separation of flue gas desulfurization and thallium-removed solids. Before generating gypsum, thallium compounds in the sodium sulfate solution are removed by adding thallium removal agents. After thallium removal, calcium hydroxide is added to the sodium sulfate solution to generate gypsum slurry, and then a certain amount of sodium carbonate is added to the gypsum slurry to neutralize some of the excessive calcium hydroxide in the gypsum slurry, reducing the risk of scaling in the absorption tower. The desulfurized saturated flue gas enters the washing tower to be mixed and cooled with low-temperature circulating water. After heat exchange, the low-temperature flue gas passes through a wet electrostatic precipitator to remove the remaining thallium and other pollutants in the saturated flue gas. The generated thallium-containing acidic condensate and the sodium sulfate solution in the absorption tower are sent to the thallium removal system together.
[0005] To achieve the above object, the present invention provides the following technical solution: A desulfurization and thallium removal process purification system for thallium-containing flue gas, including an absorption tower system, a flue gas condensation and cooling system, a thallium removal system, and a gypsum generation and dehydration system; The absorption tower system consists of a booster fan, an absorption tower, and a slurry circulation pump; The flue gas condensation and cooling system consists of a scrubbing tower, a circulating water pump, a heat exchanger, and a wet electrostatic precipitator; The thallium removal system consists of an absorption tower solution discharge pump, a thallium removal solution buffer tank, a clarifier 1, a thallium-containing sludge transfer pump, a plate and frame filter press 1, and a condensate transfer pump; The gypsum generation and dehydration system consists of a calcium hydroxide dosing tank, a sodium carbonate dosing tank, a clarifier 2, a clear water tank, a sludge transfer pump, a plate and frame filter press 2, a filtrate water pump, and a clear water pump.
[0006] Compared with the prior art, the technical effects and advantages of the present invention are as follows: For the desulfurization and thallium removal process purification system of the thallium-containing flue gas, an improved double-alkali method is used for desulfurization. Before adding calcium hydroxide to the desulfurized solution, a thallium removal agent is added for thallium removal. The thallium-containing sludge after thallium removal is disposed of separately as hazardous waste. After thallium removal, calcium hydroxide is added to the solution to generate solid waste gypsum, which can be comprehensively utilized; For the desulfurization and thallium removal process purification system of the thallium-containing flue gas, after adding calcium hydroxide to the solution, sodium carbonate is added, which reduces the concentration of Ca2+ in the solution and solves the scaling problem in the double-alkali method desulfurization process; For the desulfurization and thallium removal process purification system of the thallium-containing flue gas, the process flow is technically mature, operates safely and reliably; the cost is low, and the cost performance is high; For the desulfurization and thallium removal process purification system of the thallium-containing flue gas, a scrubbing tower and a wet electrostatic precipitator are added to the absorption tower. The saturated flue gas is mixed and heat-exchanged with low-temperature circulating water, removing other pollutants in the flue gas while removing thallium in the flue gas, making the flue gas reach ultra-super-clean; For the desulfurization and thallium removal process purification system of the thallium-containing flue gas, the solutions in the absorption tower and the scrubbing tower can enter the thallium removal solution buffer tank together for thallium removal. The process is simple and reduces the initial investment. Description of the Drawings
[0007] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0008] Figure 1 It is a schematic diagram of the present invention.
[0009] Description of the Reference Numerals in the Drawings: In the figure: 1. Booster fan; 2. Absorption tower solution discharge pump; 3. Thallium removal solution buffer tank; 4. Clarifier 1; 5. Thallium-containing sludge transfer pump; 6. Plate and frame filter press 1; 7. Calcium hydroxide dosing tank; 8. Sodium carbonate dosing tank; 9. Clarifier 2; 10. Clean water tank; 11. Sludge transfer pump; 12. Plate and frame filter press 2; 13. Filtrate water pump; 14. Filtrate water pump; 15. Heat exchanger; 16. Wet electrostatic precipitator; 17. Condensate transfer pump; 18. Slurry circulation pump. Detailed implementation manners
[0010] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other instances, some well-known technical features are not described to avoid confusion with the present invention.
[0011] Unless otherwise defined, the directions such as up, down, left, right, front, back, inside and outside involved herein are based on the up, down, left, right, front, back, inside and outside in the figures shown in the present invention, and are hereby explained together.
[0012] The connection method can adopt existing methods such as bonding, welding, bolt connection, etc., depending on actual needs. The technologies, methods and equipment known to those of ordinary skill in the relevant fields may not be discussed in detail. However, in appropriate cases, the said technologies, methods and equipment should be regarded as part of the specification, and the proportions of the devices in the drawings are for reference only and can be adjusted to a certain extent according to actual usage.
[0013] Please refer to Figure 1 As shown, a desulfurization and thallium removal process purification system for thallium-containing flue gas. This embodiment includes an absorption tower system, a flue gas condensation and cooling system, a thallium removal system, and a gypsum generation and dehydration system; The absorption tower system consists of a booster fan 1, an absorption tower, and a slurry circulation pump 18; The flue gas condensation and cooling system consists of a washing tower, a circulation water pump 14, a heat exchanger 15, and a wet electrostatic precipitator 16; The thallium removal system consists of an absorption tower solution discharge pump 2, a thallium removal solution buffer tank 3, a clarifier 1 4, a thallium-containing sludge transfer pump 5, a plate and frame filter press 1 6, and a condensate transfer pump 17; The gypsum generation and dehydration system consists of a calcium hydroxide dosing tank 7, a sodium carbonate dosing tank 8, a clarifier 2 9, a clean water tank 10, a sludge transfer pump 11, a plate and frame filter press 2 12, a filtrate water pump 13, and a clean water pump.
[0014] The raw flue gas is pressurized by the booster fan 1 and then enters the absorption tower, where it is mixed and contacted with the solution containing sodium hydroxide transported by the slurry circulation pump 18 to remove thallium and SO in the flue gas2 Pollutants such as HCL, HF, and dust. The saturated flue gas enters the scrubbing tower and exchanges heat with the circulating cooling water transported by the circulating water pump 14 after passing through the heat exchanger 15, and then enters the scrubbing tower to mix and contact with the saturated flue gas for heat exchange. The saturated flue gas after temperature reduction is discharged into the chimney after wet electrostatic precipitation and demisting by the wet electrostatic precipitator 16.
[0015] The solution in the absorption tower solution tank is transported to the thallium removal solution buffer tank 3 by the absorption tower solution discharge pump 2, and the condensed water in the scrubbing tower water tank is also transported to the thallium removal solution buffer tank 3 by the condensed water transport pump 17. Thallium removal agent is added in the thallium removal solution buffer tank 3, and the solution after thallium removal enters the clarifier 1 - 4 for separation. The solution with a high solid content at the bottom is sent to the plate and frame filter press 1 - 6 by the thallium - containing sludge transport pump 5 for solid - liquid separation. The thallium - containing sludge is disposed of separately, and the filtrate is sent to the wastewater treatment system. The supernatant of the clarifier 4 is transported to the gypsum generation and dehydration system.
[0016] The supernatant from the clarifier 1 - 4 enters the calcium hydroxide dosing tank 7 to add calcium hydroxide. The slurry for generating gypsum enters the sodium carbonate dosing tank 8, and then sodium carbonate is added to react with the excessive calcium hydroxide to form calcium carbonate. Then the slurry enters the clarifier 2 - 9 for separation. The solution with a high concentration at the bottom is transported to the plate and frame filter press 2 - 12 by the sludge transport pump 11 for pressing and solid - liquid separation. The generated gypsum can be sold externally, and the filtrate returns to the absorption tower.
[0017] It should be noted that in this article, relational terms such as "one" and "two" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.
[0018] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A desulfurization and thallium removal process purification system for thallium-containing flue gas, characterized in that: Including absorption tower system, flue gas condensation and cooling system, thallium removal system, gypsum generation and dehydration system; The absorption tower system is composed of a booster fan (1), an absorption tower, and a slurry circulation pump (18); The flue gas condensation and cooling system is composed of a washing tower, a circulating water pump (14), a heat exchanger (15), and a wet electric (16); The thallium removal system is composed of an absorption tower solution discharge pump (2), a thallium removal solution buffer tank (3), a clarifier (4), a thallium-containing sludge delivery pump (5), a plate and frame filter press (6), and a condensate delivery pump (17); The gypsum production and dehydration system is composed of a calcium hydroxide dosing tank (7), a sodium carbonate dosing tank (8), a second clarifier (9), a clean water tank (10), a sludge delivery pump (11), a second plate and frame filter press (12), a filtrate water pump (13), and a clean water pump.