Sodium ammonia process desulfurization and desulfurizer regeneration device

Abstract

The device comprises a sodium bicarbonate method desulfurization unit, an ammonium bicarbonate supply unit and a desulfurization agent regeneration unit, the sodium bicarbonate method desulfurization unit is connected with the desulfurization agent regeneration unit, and the ammonium bicarbonate supply unit is connected with the desulfurization agent regeneration unit. The desulfurizer regeneration unit regenerates sodium sulfate into sodium bicarbonate and ammonium sulfate, the sodium bicarbonate separated from the regeneration unit is reconfigured into an absorbent to return to the desulfurization unit, and an ammonium sulfate solution is processed into an ammonium sulfate solid product. The device has the advantages that the desulfurization efficiency is high (more than 98%), SO2 is recycled to produce chemical fertilizer ammonium sulfate, useless solid waste, ammonia escape and aerosol phenomena are avoided, the desulfurization cost is low, and the like.

Description

Technical Field

[0001] This utility model belongs to the field of environmental protection technology, specifically relating to a sodium ammonia desulfurization and desulfurizing agent regeneration device for flue gas. Background Technology

[0002] my country is a major coal-consuming country, with coal accounting for 75% of its total primary energy consumption. This massive energy consumption has caused severe air pollution, most notably SO2 and NOx. x The harm of acid rain caused by emissions, and NO x This causes ozone layer depletion and photochemical smog.

[0003] Currently, desulfurization and denitrification are given equal importance in my country. Existing mainstream technologies have many advantages and can meet environmental protection requirements, but their drawbacks include high investment and operating costs, low-value desulfurization byproducts such as calcium sulfate, and even secondary pollution problems. Denitrification produces only the worthless byproduct N2, yet consumes large amounts of ammonia as a reducing agent and expensive catalysts. Therefore, developing low-investment, low-cost combined desulfurization and denitrification technologies is the future direction for new technologies controlling coal-fired pollutants.

[0004] In the 21st century, the world has entered an era of knowledge economy and sustainable development, demanding a balance between development and the environment. With human progress, many resources are facing depletion and even exhaustion. The full and rational utilization of resources, even discarded resources, has become a social responsibility for contemporary scientists and engineers. Theoretically, no production process produces waste, only underutilized resources. This is also true for air pollution. SO2, currently considered one of the major air pollutants, is an important and urgently needed resource in my country. SO2 is a necessary raw material for sulfuric acid production, which in turn is a necessary raw material for fertilizer production, earning it the titles of "mother of industry and father of agriculture." Therefore, research on SO2 pollution control and recovery technologies is of great significance for mitigating acid rain damage and promoting the rational utilization of resources!

[0005] The existing desulfurization technologies mainly include the following:

[0006] Examples include lime-gypsum desulfurization (CN1281747), wet ammonia desulfurization technology (CN1226459), seawater desulfurization process (CN1262145), dual alkali desulfurization process (CN1475298), semi-dry desulfurization technology (CN101249380), circulating fluidized bed desulfurization technology (CN1401411), and electron beam desulfurization technology (Environmental Protection, 2004(9):15-18).

[0007] The lime-gypsum method is currently the most widely used desulfurization technology in China, offering high desulfurization efficiency and producing gypsum as a byproduct. However, because my country is rich in natural gypsum resources, and the quality of the gypsum produced as a byproduct differs significantly from natural gypsum in areas such as color and heavy metal content, the amount of desulfurized gypsum actually utilized in China is still limited, with most of it being stockpiled. With the large-scale construction of desulfurization projects in my country's thermal power plants, the emission of desulfurized gypsum has increased dramatically. How to properly handle this gypsum is a crucial issue. If it is disposed of through stockpiling, specialized slag yards need to be built, which not only involves huge investments and occupies a large amount of land but also easily causes dust and groundwater pollution to the surrounding environment. Furthermore, the operating costs of gypsum treatment are very high. Ammonia desulfurization, a resource-based desulfurization technology, recovers sulfur dioxide from flue gas to produce ammonium sulfate fertilizer. However, ammonia desulfurization still faces problems such as ammonia escape and aerosol (particulate matter) emissions.

[0008] The dual-alkali desulfurization process uses sodium hydroxide or sodium carbonate solution as the absorbent. Inside the desulfurization tower, SO2 is absorbed to form sodium sulfite. The sodium sulfite in the absorbent is then oxidized to form sodium sulfate. Since sodium sulfate has limited uses, inexpensive lime is used for regeneration to address the problem of desulfurization byproducts, thus forming sodium hydroxide again. This allows for the recycling of sodium ions. Sulfate ions and Ca... 2+ The gypsum formed by the combination of these two processes solves the problem of scaling inside the desulfurization tower during the lime-gypsum desulfurization process. However, like the lime-gypsum desulfurization process, the gypsum formed by the dual-alkali method has limited applications and is mostly simply stockpiled.

[0009] However, my country is a sulfur-deficient country and needs to import large quantities of sulfur from abroad every year to produce SO2 or sulfuric acid. my country is also a major SO2 emitter. Most of the existing desulfurization technologies absorb SO2 to form solid waste gypsum. A small number of desulfurization technologies use ammonia desulfurization to produce ammonium sulfate, which has fertilizer effects, but there are problems with ammonia escape and aerosols.

[0010] In summary, among existing desulfurization processes, there is currently no desulfurization technology or device that produces neither solid waste nor ammonia escape or aerosol phenomena. Existing desulfurization technologies need further improvement. Utility Model Content

[0011] The purpose of this invention is to overcome the shortcomings of the existing technology and propose a desulfurization device that can recover SO2 from flue gas, produce ammonium sulfate fertilizer, and eliminate ammonia escape and aerosol phenomena.

[0012] This invention utilizes an alkaline sodium bicarbonate solution as a desulfurization absorbent to absorb SO2 from flue gas, achieving a high removal rate and eliminating the ammonia escape and aerosol problems associated with ammonia-based desulfurization, thus achieving ultra-clean flue gas emissions. The desulfurization byproducts sodium sulfite and sodium bisulfite are oxidized with air to form sodium sulfate and sodium bisulfate, respectively. Sodium bisulfate is then neutralized with sodium bicarbonate to produce sodium sulfate. Sodium sulfate is regenerated through a metathesis reaction with ammonium bicarbonate (or by in-situ reaction of ammonia and CO2 to synthesize ammonium bicarbonate), yielding the desulfurization absorbent sodium bicarbonate and the byproduct ammonium sulfate. This regeneration of the absorbent and recovery of sulfur resources eliminates the drawbacks of the limited use and solid waste generation of the byproduct calcium sulfate in the dual-alkali method. This invention is achieved through the following technical solutions:

[0013] A sodium ammonia desulfurization and desulfurizing agent regeneration device includes a sodium bicarbonate desulfurization unit, an ammonium bicarbonate supply unit, and a desulfurizing agent regeneration unit. The sodium bicarbonate desulfurization unit is connected to the desulfurizing agent regeneration unit, and the ammonium bicarbonate supply unit is connected to the desulfurizing agent regeneration unit.

[0014] The sodium bicarbonate desulfurization unit includes a desulfurization tower, an absorbent circulation tank, a concentrate circulation tank, and a circulation pump.

[0015] The desulfurizer regeneration unit includes a metathesis reaction device, a solid-liquid separation device, a sodium bicarbonate absorbent mixing tank, and a circulating pump. The mother liquor discharge pipe on the solid-liquid separation device is connected to the mother liquor tank, and the mother liquor is sent to the subsequent process to separate ammonium sulfate solid product. In the metathesis reaction device, sodium sulfate and ammonium bicarbonate react to produce sodium bicarbonate and ammonium sulfate.

[0016] The ammonium bicarbonate supply unit includes silo equipment, metering equipment, and screw feeder; or metered ammonia or CO2 gas is introduced into the metathesis equipment to synthesize ammonium bicarbonate in situ.

[0017] The sodium bicarbonate desulfurization unit and the desulfurizing agent regeneration unit are connected via a circulating pump to produce sodium sulfate through desulfurization.

[0018] The concentrated liquid circulation tank of the sodium bicarbonate desulfurization unit is connected to the metathesis reaction equipment of the desulfurizing agent regeneration unit via a circulation pump for desulfurizing agent regeneration.

[0019] The sodium bicarbonate desulfurization unit includes a defoaming zone, an absorption zone, a concentration zone, and an oxidation zone.

[0020] The absorption zone and concentration zone shall each be equipped with at least one layer of circulating liquid distributor, and the oxidation zone shall be equipped with at least one layer of gas distributor.

[0021] The desulfurizing agent is a sodium bicarbonate solution with a concentration of 1-12% (w).

[0022] Liquid-to-gas ratio (liquid L / m³) in sodium bicarbonate desulfurization unit 3The value for gases is 0.8~15.

[0023] In the metathesis reaction apparatus, the amount of ammonium bicarbonate added is 1.0 to 1.3 times (moles) of the amount of sodium sulfate entering the metathesis reaction apparatus, the reaction temperature is 35 to 45°C, and the residence time is 0.5 to 4 hours. Brief description of the attached figures

[0024] Figure 1 This is a schematic diagram of the structure of this utility model.

[0025] Figure 1 The symbols in Chinese are explained as follows:

[0026] 1 - Desulfurization tower; 2 - Absorbent circulation tank; 3, 5, 6, 10 - Circulation pump; 4 - Concentrate circulation tank; 7 - Mother liquor tank; 8 - Solid-liquid separation equipment; 9 - Metathesis reaction equipment; 11 - Absorbent mixing tank; 12 - Flue gas inlet; 13 - Flue gas outlet; 14 - Demister; 15 - Scrubbing zone; 16, 23 - Spraying device; 17 - Gas cap; 18 - Concentration zone; 19 - Oxidation zone; 20 - Solution overflow port; 21 - Absorbent inlet; 22 - Air distributor; 24 - Absorption zone. Example

[0027] See Figure 1 Further explanation of this utility model:

[0028] The SO2-containing flue gas from the boiler fan enters the lower part of the desulfurization tower (1) through the flue gas inlet (12), and the absorbent liquid from the absorbent mixing tank (11) enters the upper part of the desulfurization tower (1) through the spray device (16). The liquid-to-gas ratio (L / m³) is as follows: 3The concentration of SO2 is 3.5. After desulfurization, the flue gas is discharged from the desulfurization tower (1) through the scrubbing zone (15) and the demister (14). The solution (desulfurization liquid) after absorbing SO2 falls from the tray where the gas cap (17) is located into the absorbent inlet (21) of the bottom of the desulfurization tower (1) and enters the oxidation zone (19) for oxidation by air. When the liquid level in the oxidation zone (19) is high, the solution overflows from the outlet (20) into the absorption circulation tank (2). The sodium sulfite and sodium bisulfite in the desulfurization liquid are oxidized by air into sodium sulfate and sodium bisulfate. After passing through the circulation pump (3), part of it is circulated to the concentration zone (18) for concentration, and the other part is returned to the spray device (16). After the liquid level in the concentrated absorption circulation tank (2) is full, it flows from the top into the concentrated liquid circulation tank (4). The pH value in the concentrated liquid circulation tank (4) is adjusted by the absorbent solution from the batching tank (11). Then, it is pumped to the metathesis reaction equipment (9) by the circulation pump (5). A metered ammonia water and CO2 are continuously added, or solid ammonium bicarbonate (the molar ratio of ammonium bicarbonate to sodium sulfate is 1.2) is added. The reaction temperature is controlled at 37~40℃ and the residence time is 2h. The reaction and crystallization occur simultaneously in the metathesis reaction equipment (9) to generate sodium bicarbonate crystals. The crystal suspension is continuously separated by the solid-liquid separation equipment (8). The mother liquor enters the mother liquor tank (7) and enters the subsequent process for separation through the circulation pump (6) to obtain ammonium sulfate product. The solid obtained by the solid-liquid separation equipment (8) falls into the batching tank (11). Process water is continuously added to the mixing tank (11), stirred and dissolved to form an absorbent solution, which is then sent to the upper part of the desulfurization tower (1) by the circulating pump (10).

[0029] The absorbent is a sodium bicarbonate solution with a concentration of 8% (w).

[0030] The advantages of this invention are: SO2-containing flue gas is treated, with a desulfurization efficiency of over 98%, achieving ultra-clean emissions while recovering ammonium sulfate products, with the N content in the ammonium sulfate reaching over 20.5%; at the same time, since there is no ammonia in the absorbent liquid, there is no ammonia escape in the outlet tail gas and no white smoke appears, thus maximizing the value of the waste gas desulfurization resource utilization process and greatly reducing desulfurization costs.

[0031] This utility model is a sodium ammonia desulfurization and desulfurizing agent regeneration device, which fully meets the needs of the desulfurization process and recovers SO2 to produce ammonium sulfate fertilizer. It also eliminates ammonia escape and aerosol phenomena, producing a useful and practical effect. It is a novel, practical and progressive new design.

[0032] The above description is merely a preferred embodiment of this utility model. Those skilled in the art, after understanding the technical means of this utility model, will naturally be able to make changes according to actual needs under the guidance of this utility model.

[0033] Therefore, all equivalent changes and modifications made within the scope of this utility model patent application shall still fall within the scope of this utility model patent.

Claims

1. A sodium ammonia desulfurization and desulfurizing agent regeneration device, characterized in that, The device includes a sodium bicarbonate desulfurization unit, an ammonium bicarbonate supply unit, and a desulfurizing agent regeneration unit. The sodium bicarbonate desulfurization unit is connected to the desulfurizing agent regeneration unit, and the ammonium bicarbonate supply unit is also connected to the desulfurizing agent regeneration unit. The sodium bicarbonate desulfurization unit includes a desulfurization tower, an absorbent circulation tank, a concentrate circulation tank, and a circulation pump. The desulfurizing agent regeneration unit includes a metathesis reaction device, a solid-liquid separation device, a sodium bicarbonate absorbent mixing tank, and a circulation pump. The mother liquor discharge pipe on the solid-liquid separation device is connected to the mother liquor tank, and the mother liquor is used to separate ammonium sulfate solid products.

2. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The ammonium bicarbonate supply unit includes silo equipment, metering equipment, and screw feeder equipment.

3. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The sodium bicarbonate desulfurization unit and the desulfurizing agent regeneration unit are connected via a circulating pump to produce sodium sulfate through desulfurization.

4. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The concentrated liquid circulation tank of the sodium bicarbonate desulfurization unit is connected to the metathesis reaction equipment of the desulfurizing agent regeneration unit via a circulation pump for desulfurizing agent regeneration.

5. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The desulfurization tower of the sodium bicarbonate desulfurization unit includes a demister zone, an absorption zone, a concentration zone, and an oxidation zone.

6. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 5, characterized in that, The absorption zone and concentration zone shall each be equipped with at least one layer of circulating liquid distributor, and the oxidation zone shall be equipped with at least one layer of gas distributor.

7. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The desulfurizing agent is a sodium bicarbonate solution with a concentration of 1-12% (w).

8. The sodium ammonia desulfurization and desulfurizing agent regeneration device as described in claim 1, characterized in that, The liquid-to-gas ratio of the sodium bicarbonate desulfurization unit is 0.8~15, and the liquid volume is L / m³. 3 gas.

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