Removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption

Abstract

The present invention relates to the technical field of flue gas treatment, and specifically to a removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, comprising a removal tower and an absorbent circulation system; the removal tower comprises, from bottom to top, a lower catalytic oxidation absorption zone, a middle absorption zone and an upper deep absorption zone. The beneficial effects of the present invention are: the removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption provided by the present invention adopts a technical process of three-zone three-circulation integrated removal to achieve simultaneous desulfurization, denitrification and decarbonization of multiple pollutants and greenhouse gases in flue gas, achieving the goal of combined desulfurization, denitrification and decarbonization of an absorbent, saving the investment cost of multi-component treatment and pollution reduction and carbon reduction equipment in flue gas, and improving the level of pollutant treatment.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment, and in particular to a removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption. Background Art

[0002] With increasingly stringent air pollutant emission standards and the gradual tightening of coal and petroleum fossil energy policies, my country's coal consumption has shown a clear downward trend, and oil demand will peak around 2025 (about 730 million tons). According to the National Bureau of Statistics, in 2020, my country's coal consumption increased by 0.6%, and its share of total energy consumption fell by 0.9 percentage points from the previous year to 56.8%. However, considering factors such as energy security, coal and oil will remain the main forms of energy consumption in my country for a long period of time in the future.

[0003] Coal combustion can produce sulfur oxides (SO x ), nitrogen oxides (NO x ), fine particulate matter and other atmospheric pollutants. Among them, SO x Most of them are sulfur dioxide (SO2) and sulfur trioxide (SO3), and the amount of SO3 is 0.1%-5% of SO2. In addition, the combustion of petroleum can also produce SO x and NO x The power and industrial sectors contribute more than 80% to SO2 emissions and NO x The contribution to emissions is close to 60%.

[0004] In order to implement the national pollution reduction and emission reduction policy, it is necessary to further control and reduce SO x and NO x Emissions. Traditional SO2 control technologies can be divided into pre-combustion desulfurization, in-combustion desulfurization and post-combustion flue gas desulfurization. Pre-combustion desulfurization refers to the removal of sulfur from coal before combustion through physical coal washing, biological / chemical coal washing, coal gasification and liquefaction, water-coal slurry technology, etc., to reduce the sulfur content in the raw coal. Physical coal washing technology is the most widely used and economical, but it can only remove inorganic sulfur; biological / chemical desulfurization can remove inorganic sulfur and organic sulfur, but the production cost is expensive and there is still a long way to go before industrial application; coal gasification and liquefaction still need further research and improvement; water-coal slurry is a new type of low-pollution oil-substitute fuel that has been commercialized, but the transportation cost of water-coal slurry is extremely high, and the equipment maintenance and replacement costs are high, which is not conducive to the large-scale use of energy. Desulfurization during combustion is in-furnace desulfurization, which is to add a certain amount of calcium or other alkaline substances as absorbents to remove SO during coal combustion. x, the general desulfurization efficiency is 20%-40%, and the typical application is the circulating fluidized bed (CFB) desulfurization technology. Post-combustion flue gas desulfurization is to install desulfurization equipment at the flue to desulfurize the flue gas. It is the most widely used. Typical technologies include wet limestone gypsum method (WFGD), etc., but this technology is difficult to capture micron-level fine mist SO3.

[0005] NO x Emission concentration and total amount are still one of the important monitoring indicators. NOx control technology can be divided into combustion control and flue gas denitrification technology. Typical technologies mainly include low-nitrogen combustion, air staging, fuel reburning, flue gas recirculation, selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR), etc. Among them, SCR technology is the most mature and widely used, but there are problems such as catalyst deactivation, ammonia leakage, and high later operating costs.

[0006] Research shows that CO2 accounts for the largest proportion of greenhouse gas emissions. Existing carbon reduction technologies mainly include carbon capture and storage and carbon resource utilization. Among them, carbon capture and storage technology has been widely studied, and pilot tests are also gradually advancing; carbon resource utilization technology is still in the laboratory research stage. In short, most carbon reduction technologies have not yet been industrialized. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, comprising a removal tower and an absorbent circulation system; the removal tower comprises, from bottom to top, a lower catalytic oxidation absorption zone, a middle absorption zone and an upper deep absorption zone;

[0009] The lower catalytic oxidation absorption zone includes a first gas distribution plate, a first spray layer, a first detachable temperature control device and a first detachable demisting device; the absorbent circulation system includes an absorbent circulation storage tank cyclically connected to the first spray layer;

[0010] The middle absorption zone includes a second gas distribution plate, a second spray layer, a second detachable temperature control device and a second detachable demisting device; the second spray layer is cyclically connected to the absorbent circulation storage tank;

[0011] The upper deep absorption zone includes a third gas distribution plate, a third spray layer, a third detachable temperature control device and a third detachable demisting device; the third spray layer is cyclically connected to the absorbent circulation storage tank.

[0012] Furthermore, in the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, the first detachable temperature control device, the second detachable temperature control device and the third detachable temperature control device all include anti-corrosion coils filled with media.

[0013] Furthermore, in the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, the absorption medium in the anti-corrosion coil is air, water or heat transfer oil.

[0014] Furthermore, in the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, the first spray layer includes a plurality of first atomizing nozzles, the first absorbent circulation system includes a first circulation pump, and the first atomizing nozzle, the first circulation pump and the absorbent circulation storage tank are connected by a pipeline;

[0015] The second spray layer includes a plurality of second atomizing nozzles, the second absorbent circulation system includes a circulation pump, and the second atomizing nozzles, the second circulation pump and the absorbent circulation storage tank are connected by pipelines;

[0016] The third spray layer includes a plurality of third atomizing nozzles, the third absorbent circulation system includes a third circulation pump, and the third atomizing nozzles, the third circulation pump and the absorbent circulation storage tank are connected by pipelines.

[0017] Furthermore, in the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, an absorbent is arranged in the absorbent circulation storage tank, and the absorbent is a mixed solution of one or more reagents selected from the group consisting of sodium hydroxide, sodium hypochlorite, sodium chlorite, triethanolamine, ethylenediamine, ammonia water, sodium metaborate, sodium carbonate and sodium chloride dissolved in solvent water or hydrogen peroxide, and the solute mass percentage of hydrogen peroxide is 0.5%-2.5%.

[0018] Furthermore, in the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, the absorbent is obtained by dissolving sodium hypochlorite and sodium hydroxide in water, the mass percentage of sodium hypochlorite in the absorbent is 1.0%, and the mass percentage of sodium hydroxide in the absorbent is 0.5%.

[0019] The beneficial effect of the present invention is that most of the existing desulfurization and denitrification technologies use independent desulfurization and denitrification systems, which require initial investment and later operation and maintenance respectively, and there are currently no examples of decarbonization technologies that can be applied and promoted on a large scale in China. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption provided by the present invention adopts a technical process of three-zone three-cycle integrated removal to achieve simultaneous desulfurization, denitrification and decarbonization of multiple pollutants and greenhouse gases in flue gas, which can achieve the goal of combined desulfurization, denitrification and decarbonization of an absorbent, save the investment cost of multi-component treatment and pollution reduction and carbon reduction equipment in flue gas, and improve the level of pollutant treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A removal device for simultaneous desulfurization, denitration and decarbonization based on wet absorption according to a specific embodiment of the present invention;

[0021] Description of labels:

[0022] 1. Lower catalytic oxidation absorption zone; 11. First air distribution plate; 12. First spray layer; 13. First detachable temperature control device; 14. First detachable demisting device; 15. First circulation pump;

[0023] 2. Middle absorption zone; 21. Second air distribution plate; 22. Second spray layer; 23. Second detachable temperature control device; 24. Second detachable demisting device; 25. Second circulation pump;

[0024] 3. Upper deep absorption zone; 31. Third air distribution plate; 32. Third spray layer; 33. Third detachable temperature control device; 34. Third detachable demisting device; 35. Third circulation pump;

[0025] 4. Absorbent circulation storage tank; 5. Flue gas heat exchange device; 6. Water washing device; 7. Absorbent new liquid storage tank; 8. Chimney. DETAILED DESCRIPTION

[0026] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0027] Example 1

[0028] Please refer to Figure 1 , a removal device for simultaneous desulfurization, denitration and decarbonization based on wet absorption, comprising a removal tower and an absorbent circulation system; the removal tower comprises, from bottom to top, a lower catalytic oxidation absorption zone 1, a middle absorption zone 2 and an upper deep absorption zone 3;

[0029] The lower catalytic oxidation absorption zone 1 includes a first gas distribution plate 11, a first spray layer 12, a first detachable temperature control device 13 and a first detachable demisting device 14; the absorbent circulation system includes an absorbent circulation storage tank 4 which is cyclically connected to the first spray layer 12;

[0030] The middle absorption zone 2 comprises a second gas distribution plate 21, a second spray layer 22, a second detachable temperature control device 23 and a second detachable demisting device 24; the second spray layer 22 is cyclically connected to the absorbent circulation storage tank 4;

[0031] The upper deep absorption zone 3 comprises a third gas distribution plate 31 , a third spray layer 32 , a third detachable temperature control device 33 and a third detachable demisting device 34 ; the third spray layer 32 is in circulation communication with the absorbent circulation storage tank 4 .

[0032] The first detachable temperature control device 13, the second detachable temperature control device 23 and the third detachable temperature control device 33 all include an anti-corrosion coil filled with a medium. The absorption medium in the anti-corrosion coil is air, water or heat transfer oil.

[0033] The first spray layer 12 includes a plurality of first atomizing nozzles, the first absorbent circulation system includes a first circulation pump 15, and the first atomizing nozzle, the first circulation pump 15 and the absorbent circulation tank 4 are connected by a pipeline; the second spray layer 22 includes a plurality of second atomizing nozzles, the second absorbent circulation system includes a circulation pump, and the second atomizing nozzle, the second circulation pump 25 and the absorbent circulation tank 4 are connected by a pipeline; the third spray layer 32 includes a plurality of third atomizing nozzles, the third absorbent circulation system includes a third circulation pump 35, and the third atomizing nozzle, the third circulation pump 35 and the absorbent circulation tank 4 are connected by a pipeline.

[0034] The absorbent circulation storage tank 4 is provided with an absorbent, and the absorbent is sodium hydroxide (NaOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO2), triethanolamine (C6H 15 One or more of the following reagents: NO3), ethylenediamine (C2H8N2), ammonia water (NH3·H2O), sodium metaborate (NaBO2·2H2O), sodium carbonate (Na2CO3), and sodium chloride (NaCl) are mixed and dissolved in a solvent water or a mixed solution of hydrogen peroxide, wherein the mass percentage of the solute of hydrogen peroxide is 0.5%-2.5%

[0035] The present invention uses a removal device for simultaneous desulfurization, denitration and decarbonization based on wet absorption:

[0036] The absorbent is delivered to the absorbent fresh liquid storage tank through a feeder, a meter and a powder conveyor, the absorbent is configured in the absorbent fresh liquid storage tank 7, and the configured absorbent is pumped into the absorbent circulation storage tank 4 at the bottom of the removal tower through a circulation pipeline with a flow meter by a slurry circulation pump;

[0037] After the tail flue gas after dust removal has been heat exchanged in the flue gas heat exchange device 5, it enters the lower catalytic oxidation absorption zone 1 in the tower from the bottom of the removal tower, and is sprayed out in the first gas distribution plate 11. The absorbent circulation storage tank 4 is connected to a slurry circulation pump, and the slurry circulation pump sends the absorbent from the absorbent circulation storage tank 4 to the multiple atomizing nozzles of the first spray layer 12 of the lower catalytic oxidation absorption zone 1 for spraying. The absorbent after spraying is recycled to the absorbent circulation storage tank 4 below the removal tower. The flue gas and the atomized absorbent undergo gas-liquid convection absorption and desulfurization, denitrification and decarbonization reactions; a detachable temperature control device is also provided in the lower catalytic oxidation absorption zone 1, and the detachable temperature control device includes an anti-corrosion coil filled with a medium, and the anti-corrosion coil performs gas-liquid or gas-to-gas heat exchange with the flue gas outside the coil; a detachable demisting device is provided on the upper part of the lower catalytic oxidation absorption zone 1, and the detachable demisting device performs a primary demisting on the residual products of the convection absorption reaction, and the remaining flue gas enters the middle absorption zone 2 of the removal device;

[0038] After the flue gas enters the middle absorption zone 2, it is sprayed out in the second gas distribution plate 21. The slurry circulation pump sends the absorbent in the absorbent circulation storage tank 4 to the multiple atomizing nozzles of the second spray layer 22 of the middle absorption zone 2 for spraying. The absorbent after spraying is recycled to the absorbent circulation storage tank 4 below the removal tower. The flue gas sprayed out from the second gas distribution plate 21 reacts with the absorbent for desulfurization, denitrification and decarbonization again. The medium in the anti-corrosion coil of the second detachable temperature control device 23 continues to exchange gas-liquid or gas-gas heat with the flue gas outside the coil. After that, the flue gas enters the upper deep absorption zone 3 of the removal device after being defogged by the second detachable demisting device 24 of the middle absorption zone 2.

[0039] After the flue gas enters the upper deep absorption zone 3, it is sprayed out in the third gas distribution plate 31. The slurry circulation pump sends the absorbent in the absorbent circulation storage tank 4 to the multiple atomizing nozzles of the third spray layer 32 of the upper deep absorption zone 3 for spraying. The sprayed absorbent is recycled to the absorbent circulation storage tank 4 below the removal tower. The atomized absorbent undergoes a deep absorption reaction with the flue gas, and the medium in the anti-corrosion coil of the detachable temperature control device continues to exchange gas-liquid or gas-gas heat with the flue gas outside the coil. After that, the flue gas is defogged by the detachable defogger in the deep absorption zone, and then the flue gas passes through the water washing device 6 and is discharged through the chimney 8;

[0040] The desulfurization, denitration and decarbonization products in the absorbent circulation storage tank 4 recycled from the three zones can be used as agricultural fertilizers or other resource utilization after evaporation and low-temperature crystallization. The medium in the temperature-controlled anti-corrosion coil can be used for heat transfer, mass transfer or combustion processes.

[0041] The process conditions of the desulfurization, denitration and decarbonization removal device based on wet absorption are as follows: flue gas temperature is 10-50°C, absorbent solute mass concentration is 0.5%-15%, liquid-gas ratio is 5-20L / m 3The pH value of the absorbent slurry circulation is 4.5-10.5, the slurry temperature is 5-45°C, the desulfurization efficiency is 90%-99.99%, the denitrification efficiency is 41%-85%, and the decarbonization efficiency is 10%-50%.

[0042] The use example of the above-mentioned removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption is as follows, wherein the flue gas is flue gas generated by a boiler, and the pollutants in the flue gas include sulfur dioxide (SO2), sulfur trioxide (SO3), hydrogen sulfide (H2S), nitric oxide (NO), nitrogen dioxide (NO2), and the greenhouse gas is carbon dioxide (CO2).

[0043] 1. The flue gas temperature is 12℃, the absorbent is NaClO and NaOH dissolved in water, the solute mass percentage is NaClO1.0%-NaOH0.5%, and the liquid-gas ratio is 10L / m 3 , the pH of absorbent slurry and absorbent slurry circulation is 5.5, the slurry temperature is 35°C, the desulfurization efficiency is 98%, the denitrification efficiency is 70%, and the decarbonization efficiency is 30%;

[0044] 2. Flue gas temperature is 20℃, absorbent solute mass percentage is NH3·H2O1.5%-NaOH 0.1%, liquid-gas ratio is 15L / m 3 , the pH of absorbent slurry and absorbent slurry circulation is 5.5, the slurry temperature is 25°C, the desulfurization efficiency is 99%, the denitrification efficiency is 75%, and the decarbonization efficiency is 45%;

[0045] 3. Flue gas temperature is 50℃, absorbent solute mass percentage is C2H8N21.3%-Na2CO3 0.8%, liquid-gas ratio is 7L / m 3 , the pH of absorbent slurry and absorbent slurry circulation is 6.0, the slurry temperature is 45°C, the desulfurization efficiency is 90%, the denitrification efficiency is 42%, and the decarbonization efficiency is 10%;

[0046] 4. Flue gas temperature is 45℃, absorbent solute mass percentage is Na2CO311.6%-NaBO2·2H2O 0.4%, liquid-gas ratio is 12L / m 3 , the pH of the absorbent slurry and the absorbent slurry circulation was 5.0, the slurry temperature was 30°C, the desulfurization efficiency was 95%, the denitrification efficiency was 67%, and the decarbonization efficiency was 14%.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption, characterized in that: It includes a removal tower and an absorbent circulation system; the removal tower includes a lower catalytic oxidation absorption zone, a middle absorption zone and an upper deep absorption zone from bottom to top; The lower catalytic oxidation absorption zone includes a first gas distribution plate, a first spray layer, a first detachable temperature control device and a first detachable demisting device; the absorbent circulation system includes an absorbent circulation storage tank cyclically connected to the first spray layer; The middle absorption zone includes a second gas distribution plate, a second spray layer, a second detachable temperature control device and a second detachable demisting device; the second spray layer is cyclically connected to the absorbent circulation storage tank; The upper deep absorption zone includes a third gas distribution plate, a third spray layer, a third detachable temperature control device and a third detachable demisting device; the third spray layer is cyclically connected to the absorbent circulation storage tank.

2. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption according to claim 1 is characterized in that: The first detachable temperature control device, the second detachable temperature control device and the third detachable temperature control device all include an anti-corrosion coil filled with a medium.

3. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption according to claim 2 is characterized in that: The absorption medium in the anti-corrosion coil is air, water or heat transfer oil.

4. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption according to claim 1 is characterized in that: Also included is a first absorbent circulation system, a second absorbent circulation system and a third absorbent circulation system; The first spray layer includes a plurality of first atomizing nozzles, the first absorbent circulation system includes a first circulation pump, and the first atomizing nozzles, the first circulation pump and the absorbent circulation storage tank are connected by pipelines; The second spray layer includes a plurality of second atomizing nozzles, the second absorbent circulation system includes a circulation pump, and the second atomizing nozzles, the second circulation pump and the absorbent circulation storage tank are connected by pipelines; The third spray layer includes a plurality of third atomizing nozzles, the third absorbent circulation system includes a third circulation pump, and the third atomizing nozzles, the third circulation pump and the absorbent circulation storage tank are connected by pipelines.

5. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption according to claim 1 is characterized in that: The absorbent circulation storage tank is provided with an absorbent, which is a mixed solution of one or more reagents selected from sodium hydroxide, sodium hypochlorite, sodium chlorite, triethanolamine, ethylenediamine, ammonia water, sodium metaborate, sodium carbonate and sodium chloride dissolved in solvent water or hydrogen peroxide, and the solute mass percentage of the hydrogen peroxide is 0.5%-2.5%.

6. The removal device for simultaneous desulfurization, denitrification and decarbonization based on wet absorption according to claim 1 is characterized in that: The absorbent is obtained by dissolving sodium hypochlorite and sodium hydroxide in water, wherein the mass percentage of sodium hypochlorite in the absorbent is 1.0%, and the mass percentage of sodium hydroxide in the absorbent is 0.5%.

Images