A method for regenerating H2S desulfurizer and combining desulfurization and denitrification

Abstract

The present invention discloses a method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying, which specifically comprises the following steps: (1) Soaking or rinsing a saturated H2S desulfurizer with a caustic alkali solution, filtering and then washing with water; meanwhile, mixing the soaking solution or rinsing solution and the washing solution to obtain a desulfurization and denitrification solution; (2) Transferring to a dry regeneration device and purging with a gas containing an excessive oxidant, i.e., the regeneration is completed; meanwhile, collecting the purged gas to obtain a purge gas; (3) Mixing the purge gas and a flue gas containing NO / SO2 and reacting to obtain a mixed flue gas containing NO2 / SO3; (4) Spraying and washing the mixed flue gas containing NO2 / SO3 with the desulfurization and denitrification solution, and discharging the flue gas up to the standard. The method of the present invention can not only achieve the complete regeneration of the H2S desulfurizer, but also resourcefully utilize the regeneration waste liquid, purify the flue gas containing NO / SO2, and has both economic benefits and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental engineering, and more specifically to a method for regenerating H2S desulfurizer and jointly desulfurizing and denitrifying flue gas. Background Art

[0002] Hydrogen sulfide (chemical formula: H2S) is a common toxic gas, which is widely generated in industries such as steel, gas, coal chemical industry, synthetic ammonia, sewage treatment and papermaking.

[0003] H2S desulfurizer usually refers to an adsorption or catalytic material prepared by loading active components on carriers such as activated carbon and molecular sieve. Its characteristic is that it has a certain oxidation ability on the surface, can adsorb and oxidize H2S into elemental S and attach it to the surface of the desulfurizer, and the waste gas is purified.

[0004] Due to the complexity of the waste gas conditions, the removal of H2S often takes place in a high-temperature and high-humidity environment, which causes some H2S and active metals to easily combine to form sulfides, leading to a decline in the function of the active components. The accumulation of elemental S on the surface of the desulfurizer and the formation of sulfides are the main reasons for the inactivation of the desulfurizer. Since the amount of H2S waste gas generated in various industries is huge, if the inactivated desulfurizer is directly discarded without regeneration and reuse, it will cause huge waste of resources and a mountain of hazardous waste.

[0005] The current mainstream methods for regenerating H2S desulfurizer mainly include wet method and dry method. However, wet regeneration will produce a large amount of waste water and the S resources cannot be recycled; while dry regeneration requires high-temperature purging with inert gas, and to realize the resource utilization of S, the high-temperature regeneration gas must be condensed, consuming a large amount of energy. In addition, neither the dry method nor the wet method can achieve 100% regeneration. The reason is that the existing regeneration methods can only remove the elemental S on the surface of the desulfurizer and cannot regenerate the active components, which results in a decrease in the desulfurization ability of the regenerated desulfurizer. Enterprises need to frequently replace the desulfurizer, leading to the complication of operation and the waste of labor costs. At the same time, in industries such as electric power, steel, coal chemical industry, and electronics, due to the combustion of coal and the use of acidic gases, a large amount of flue gas containing both NO / SO2 will be generated. The treatment of these flue gases will also cause huge consumption of resources and energy, increasing the burden on enterprises. Thus, it can be seen that in many industries, H2S waste gas and NO / SO2 flue gas coexist. If a process method that can simultaneously achieve the complete regeneration of H2S desulfurizer and remove NO / SO2 in the flue gas can be developed, it can not only greatly alleviate the above-mentioned waste of resources and energy, but also achieve the up-to-standard discharge of flue gas, reducing the economic and environmental protection pressure on enterprises.

[0006] The invention patent "Regeneration Method of Renewable Composite Metal Oxide High-Temperature Coal Gas Desulfurizer" with the application publication number CN 106147885 A, the bed temperature is 600 - 750 °C, and the space velocity is 1000 - 3000 h-1 , the composition of the regeneration gas is 1-3% SO2 balanced with N2. When the concentration of elemental sulfur at the outlet is less than 1 ppm, the regeneration is stopped; during the regeneration of the desulfurizer, the gas at the reactor outlet is cooled to below 70°C, and elemental sulfur in the gas is separated and recovered, and the remaining regeneration gas is recycled for the next step; at the end of the regeneration process, the regenerated desulfurizer is used for the next round of desulfurization, and all the regeneration products are elemental sulfur. Although this invention recovers the S on the surface of the desulfurizer, it cannot restore the sulfided active metal. In addition, the treatment method of SO2 in the regeneration gas is not mentioned.

[0007] The invention patent "A regeneration method of hydrogen sulfide desulfurizer" with the authorization announcement number CN 102489278 B adopts the method of leaching or soaking-leaching combination, and the reagent is acetone, cyclohexane or tetrachloromethane. The eluate can be collected and recycled until the concentration of elemental sulfur in the eluate is stable. This invention recovers the S on the surface of the desulfurizer by wet method, but it also cannot restore the sulfided active metal, and the desulfurizer adsorbed with organic matter needs further treatment. In addition, this invention will produce desulfurization waste liquid.

[0008] The invention "A method for simultaneous desulfurization and denitrification by ozone staged oxidation combined with wet absorption" with the application publication number CN 112138525 A adds ozone to the flue gas to oxidize NO x , and then uses a wet scrubbing and absorption system to absorb the gas product after the oxidation reaction; during the ozone oxidation process, the ozone addition amount is controlled in stages according to the emission standards for flue gas desulfurization and denitrification treatment. Although this invention oxidizes NO to NO2, it does not realize the resource utilization of waste, let alone mention the regeneration of H2S desulfurizer, and the wet absorption uses the traditional CaCO3 / CaO slurry.

[0009] Therefore, how to develop a method for the regeneration of H2S desulfurizer combined with desulfurization and denitrification is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a method for the regeneration of H2S desulfurizer combined with desulfurization and denitrification to solve the deficiencies in the prior art. This method can not only achieve the complete regeneration of H2S desulfurizer, but also recycle the regeneration waste liquid, purify the flue gas containing NO / SO2, and has both economic and environmental benefits.

[0011] To achieve the above purpose, the present invention adopts the following technical solutions:

[0012] A method for the regeneration of H2S desulfurizer combined with desulfurization and denitrification specifically includes the following steps:

[0013] (1) Wet regeneration of H2S desulfurizer

[0014] The saturated H2S desulfurizer is soaked or rinsed with a caustic alkali solution, and after filtration, the H2S desulfurizer is washed with water to obtain the H2S desulfurizer after wet regeneration;

[0015] Meanwhile, the soaking solution or rinsing solution and the washing solution are mixed to obtain a desulfurization and denitrification solution;

[0016] (2) Dry regeneration of H2S desulfurizer

[0017] The H2S desulfurizer after wet regeneration is transferred to a dry regeneration device, and the H2S desulfurizer after wet regeneration is purged with a gas containing an excessive amount of oxidant, and the regeneration of the H2S desulfurizer is completed;

[0018] Meanwhile, the purged gas is collected to obtain a purge gas;

[0019] (3) Preparation of mixed flue gas

[0020] The purge gas in step (2) and the flue gas containing NO / SO2 are mixed and reacted to obtain a mixed flue gas containing NO2 / SO3;

[0021] (4) Desulfurization and denitrification of mixed flue gas

[0022] The mixed flue gas containing NO2 / SO3 in step (3) is spray-washed with the desulfurization and denitrification solution in step (1), and the flue gas is discharged up to the standard.

[0023] Furthermore, in the above step (1), the H2S desulfurizer is a supported desulfurizer, including a carrier and an active component or an auxiliary agent; wherein, the carrier is activated carbon, activated carbon fiber, molecular sieve or zeolite, and the active component or auxiliary agent is a metal oxide, and the metal oxide includes but is not limited to oxides of Cu, Fe, Zn, Mn, Al, Co, Ce, Mo, La, Zr, V, Cr.

[0024] Furthermore, in the above step (1), the caustic alkali is NaOH or KOH; the mass concentration of the caustic alkali in the caustic alkali solution is 1% - 30%; the liquid-solid ratio of the caustic alkali solution and the saturated H2S desulfurizer is 5 - 50 L / kg.

[0025] The beneficial effect of adopting the above further technical solution is that when preparing the caustic alkali solution, solid NaOH or KOH is added to a certain volume of tap water for dissolution to obtain a regeneration solution. Then, the saturated H2S desulfurizer is soaked in a container or rinsed with a rinsing device, so that the S element on the surface of the saturated H2S desulfurizer fully reacts with the caustic alkali to generate an alkaline solution of Na2S or K2S. The reaction formula is as follows:

[0026] 3S + 6NaOH = 2Na2S + Na2SO3 + 3H2O (1)

[0027] 3S + 6KOH = 2K2S + Na2SO3 + 3H2O (2)

[0028] Further, in the above step (1), the temperature for soaking or rinsing is 20 - 100 °C, and the time is more than 30 min. Furthermore, the H2S desulfurizer is soaked or rinsed according to the type of the H2S desulfurizer carrier. Specifically: for the H2S desulfurizer with activated carbon or activated carbon fiber as the carrier, soaking is selected as the wet regeneration method; for the H2S desulfurizer with molecular sieve or zeolite as the carrier, rinsing is selected as the wet regeneration method.

[0029] Further, in the above step (1), it is washed until the pH of the washing liquid ≤ 9.

[0030] Further, in the above step (2), the oxidant is at least one of O3, O2, hydroxyl radical, and ClO2.

[0031] The beneficial effect of adopting the above further technical solution is that the dry regeneration process of the H2S desulfurizer is carried out in specific equipment, and the specific equipment includes but is not limited to a desulfurization tower, a tubular furnace, a fixed bed, a moving bed, and a fluidized bed. The purpose of the dry regeneration of the H2S desulfurizer is to restore the sulfided metal to the oxidized state to achieve the complete regeneration of the desulfurizer (regeneration efficiency ≥ 99%). Taking the active component as CuO and the oxidant as O2 as an example, the reaction formula is as follows:

[0032] 2CuS + 3O2 = 2CuO + 2SO2 (3)

[0033] Furthermore, in the above step (2), the gas is at least one of air, flue gas containing NO x / SO x , clean flue gas, N2, and other inert gases except N2.

[0034] Further, in the above step (2), the temperature of the purge gas is 20 - 150 °C; the space velocity of the purge is 2000 - 20000 h -1 , the time ≥ 30 min; it is purged until the SO2 concentration in the purge gas is reduced to below 1 ppm. Preferably, the specific temperature of the purge gas needs to be determined according to the type of the oxidant and the type of the gas. For example, when using a relatively weak oxidant such as O2, it needs to be heated to a higher temperature; when using relatively strong oxidants such as O3 and hydroxyl radical, no heating or only appropriate heating is required; when using an oxidant with moderate oxidizing property such as ClO2, only appropriate heating is required. When the gas is flue gas containing NO x / SO x , it needs to be appropriately heated to ensure NO x / SO x It is not physically adsorbed on the surface of the H2S desulfurizer, and the purge gas should be kept dry to avoid nitration or sulfation of the active metal; when using air, clean flue gas, N2, or other inert gases except N2 as the purge gas, heating and drying are not required.

[0035] Furthermore, in the above step (3), the reaction device is a flue gas mixing tank or a flue, and the time > 2 s. Preferably, the flue gas mixing tank is spherical or ellipsoidal, and there should be no dead corners in the flue gas mixing tank to ensure complete and uniform mixing of the gas.

[0036] The beneficial effect of adopting the above further technical solution is that by reacting the purge gas and the flue gas containing NO / SO2 in the flue gas mixing tank or the flue in step (2), the remaining oxidant in the purge gas in step (2) can be used to oxidize NO and SO2 into NO2 and SO3 respectively.

[0037] Furthermore, in the above step (4), the device for spray washing is a vertical packed spray tower or a horizontal packed spray tower. Further, the packing in the spray tower includes but is not limited to Pall rings, Raschig rings, and hollow spheres, and the packing material includes but is not limited to PP, PE, PVC, and Teflon. To ensure that the equipment and pipelines are not corroded, the flue gas mixing tank, flue in step (3), and the spray tower in step (4) should be made of anti-corrosion materials, or an anti-corrosion material should be coated on the inner layer of the flue gas mixing tank, flue, and spray tower.

[0038] The beneficial effect of adopting the above further technical solution is that in step (4), the desulfurization and denitrification liquid generated in step (1) is used to remove the NO2 and SO3 oxidized in step (3). Taking the regeneration liquid as an aqueous solution of NaOH, that is, the desulfurization and denitrification liquid is a NaOH solution of Na2S as an example, the reaction formula is as follows:

[0039] 2Na2S + 8NO2 + 6NaOH = 8NaNO2 + Na2S2O3 + 3H2O (4)

[0040] 2NaOH + SO3 = Na2SO4 + H2O (5)

[0041] In addition, the desulfurization and denitrification liquid in step (4) is recycled. After removing NO2 / SO3 and other acidic substances in the flue gas, the flue gas meets the standards and is directly discharged. The desulfurization and denitrification liquid is determined whether to be replaced according to the monitoring of the conductivity and the outlet NO x 、SO x concentration, that is, when its conductivity ≥ 50 ms / cm 2 or the NO in the flue gas at the outlet of the desulfurization and denitrification device x 、SO xWhen it exceeds the standard, it is determined that the desulfurization and denitrification liquid has failed. At this time, the failed desulfurization and denitrification liquid is discharged and fresh desulfurization and denitrification liquid is replenished. The failed desulfurization and denitrification liquid is treated as sewage and can be discharged into the factory's sewage treatment system, or mixed salts can be obtained through evaporation and concentration for solid waste treatment.

[0042] As can be seen from the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] (1) The present invention can completely regenerate the failed H2S desulfurizer, greatly reduce the replacement frequency of the H2S desulfurizer, extend the service life of the H2S desulfurizer, and reduce the enterprise cost;

[0044] (2) The present invention resourcefully utilizes the waste liquid from the regeneration of the H2S desulfurizer and uses it for simultaneous desulfurization and denitrification in the factory. While realizing waste resource utilization, it reduces emissions, combining economic and environmental benefits;

[0045] (3) The waste liquid from the regeneration of the H2S desulfurizer (desulfurization and denitrification liquid) in the present invention is strongly alkaline. While realizing flue gas desulfurization and denitrification, it can also remove other acidic substances in the flue gas, achieving ultra-low emissions;

[0046] (4) The method of the present invention has a simple process and is easy to operate, and the operating temperature of each link is lower than 150 °C, with low safety risks.

[0047] (5) The present invention combines economic and environmental benefits, completely regenerates the H2S desulfurizer at low temperature, realizes waste utilization, and the regenerated waste liquid (desulfurization and denitrification liquid) is reused for flue gas desulfurization and denitrification, simultaneously achieving the purpose of energy conservation and emission reduction, and is suitable for market and industrial promotion and application. Description of the Drawings

[0048] Figure 1 It is a schematic diagram of the device and process flow of the H2S desulfurizer regeneration combined with desulfurization and denitrification method (soaking) in Embodiments 1-2 of the present invention;

[0049] Figure 2 It is a schematic diagram of the device and process flow of the H2S desulfurizer regeneration combined with desulfurization and denitrification method (spray washing) in Embodiment 3 of the present invention.

[0050] Figure 1 and Figure 2 In, 1 - caustic alkali solution storage tank, 2 - caustic alkali solution dosing pump, 3 - wet regeneration device, 4 - electric heater, 5 - dry regeneration device, 6 - thermometer, 7 - flue gas mixing tank, 8 - desulfurization and denitrification liquid storage tank, 9 - desulfurization and denitrification tower, 10 - desulfurization and denitrification liquid circulation pump, 11 - flue gas on-line monitor, 12 - conductivity meter, 13 - flue gas fan. Detailed Embodiments

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] An embodiment of the present invention discloses a combined H2S desulfurizer regeneration and desulfurization and denitrification system, as Figure 1 or Figure 2 shown, which includes a caustic alkali solution storage tank 1, a wet regeneration device 3, a dry regeneration device 5, a flue gas mixing tank 7, a desulfurization and denitrification liquid storage tank 8, and a desulfurization and denitrification tower 9; wherein, the caustic alkali solution storage tank 1, the wet regeneration device 3, the desulfurization and denitrification liquid storage tank 8, and the desulfurization and denitrification tower 9 are connected in sequence, and the dry regeneration device 5, the flue gas mixing tank 7, and the desulfurization and denitrification tower 9 are connected in sequence. In the present invention, the caustic alkali solution storage tank 1 is used to store the caustic alkali solution. The wet regeneration device 3 is used to soak or wash the saturated H2S desulfurizer with the caustic alkali solution, and then wash the H2S desulfurizer with water after filtration to obtain the wet regenerated H2S desulfurizer; at the same time, the soaking liquid or washing liquid and the washing water are mixed to obtain the desulfurization and denitrification liquid. The dry regeneration device 5 is used to transfer the wet regenerated H2S desulfurizer to the dry regeneration device 5, and blow the wet regenerated H2S desulfurizer with a gas containing an excessive amount of oxidant, and the H2S desulfurizer is regenerated; at the same time, the blown gas is collected to obtain the blown gas. The flue gas mixing tank 7 is used to mix and react the blown gas and the flue gas containing NO / SO2 to obtain a mixed flue gas containing NO2 / SO3. The desulfurization and denitrification liquid storage tank 8 is used to store the desulfurization and denitrification liquid. The desulfurization and denitrification tower 8 is used to spray and wash the mixed flue gas containing NO2 / SO3 with the desulfurization and denitrification liquid, and the flue gas is discharged up to standard.

[0053] In one embodiment, it further includes a caustic alkali solution dosing pump 2; the caustic alkali solution dosing pump 2 is arranged between the caustic alkali solution storage tank 1 and the wet regeneration device 3. The caustic alkali solution dosing pump 2 is used to pump the caustic alkali solution in the caustic alkali solution storage tank 1 into the wet regeneration device 3 for wet regeneration treatment of the H2S desulfurizer.

[0054] In one embodiment, it further includes an electric heater 4; the electric heater 4 is connected to the dry regeneration device 5. During the dry regeneration process of the H2S desulfurizer, when the gas used is flue gas containing NO x / SO x , it is necessary to appropriately heat with the electric heater 4 to ensure that NO x / SO x is not physically adsorbed on the surface of the H2S desulfurizer.

[0055] In one embodiment, it further includes a thermometer 6; the thermometer 6 is connected to the dry regeneration device 5. During the dry regeneration process of the H2S desulfurizer, the thermometer 6 is used to detect and control the temperature of the purge gas to be 20 - 150 °C.

[0056] In one embodiment, it further includes a desulfurization and denitrification liquid circulation pump 10; the inlet of the desulfurization and denitrification liquid circulation pump 10 is connected to the bottom of the desulfurization and denitrification tower 9, and the outlet of the desulfurization and denitrification liquid circulation pump 10 is connected to the top of the desulfurization and denitrification tower 9. During the process of hybrid flue gas desulfurization and denitrification, the desulfurization and denitrification liquid is circulated using the desulfurization and denitrification liquid circulation pump 9. After removing NO2 / SO3 and other acidic substances in the flue gas, the flue gas is discharged directly up to standard.

[0057] In one embodiment, it further includes an on-line flue gas monitor 11; the on-line flue gas monitor 11 is connected to the top of the desulfurization and denitrification tower 9.

[0058] In one embodiment, it further includes a conductivity meter 12; the conductivity meter 12 is connected to the bottom of the desulfurization and denitrification tower 9. During the process of hybrid flue gas desulfurization and denitrification, during the process of hybrid flue gas desulfurization and denitrification, the desulfurization and denitrification liquid is determined whether to be replaced according to the conductivity measured by the conductivity meter 12 and the outlet NO x 、SO x concentration, that is, when its conductivity ≥ 50 ms / cm 2 or the NO in the flue gas at the outlet of the desulfurization and denitrification device x 、SO x exceeds the standard, it is determined that the desulfurization and denitrification liquid fails. At this time, the failed desulfurization and denitrification liquid is discharged and fresh desulfurization and denitrification liquid is replenished.

[0059] In one embodiment, it further includes a flue gas fan 13; the flue gas fan 13 is arranged downstream of the desulfurization and denitrification tower 9. The flue gas fan 13 is used for the up-to-standard discharge of the flue gas.

[0060] Example 1

[0061] The H2S desulfurizer for blast furnace gas of a certain iron and steel enterprise is prepared by loading 5% MnO2 on activated carbon. 1000 kg of saturated H2S desulfurizer is taken for regeneration.

[0062] The method for the combined desulfurization and denitrification of the H2S desulfurizer regeneration is as Figure 1 shown, and specifically includes the following steps:

[0063] (1) Wet regeneration of the H2S desulfurizer

[0064] Prepare a NaOH solution with a mass concentration of 10% in the caustic alkali solution storage tank 1, place 1000 kg of saturated H2S desulfurizer in the wet regeneration device 3, and add 10 m in the wet regeneration device 3 using the caustic alkali solution dosing pump 23 The NaOH solution is used to soak the H2S desulfurizer at room temperature for 5 hours until the NaOH solution gradually changes from colorless and transparent to yellow. Then, it is filtered, and the soaking solution is introduced into the desulfurization and denitrification liquid storage tank 8 for temporary storage. Then, the tap water valve is opened, and the soaked H2S desulfurizer is washed 4 times in the wet regeneration device 3, with 10 m of tap water flowing in each time 3 , until the pH of the washing solution is 8, and the H2S desulfurizer after wet regeneration is obtained. Finally, the washing solution is introduced into the desulfurization and denitrification liquid storage tank 8 to be mixed with the soaking solution to obtain the desulfurization and denitrification liquid;

[0065] (2) Dry regeneration of H2S desulfurizer

[0066] Transfer the H2S desulfurizer after wet regeneration to the dry regeneration device 5, and use an electric heater 4 to heat the air containing 1000 ppm O 3 at a flow rate of 5000 m / h to 50 °C measured by the thermometer 6, and blow the H2S desulfurizer after wet regeneration. Use a handheld SO2 detector to detect the blowing gas at the outlet of the dry regeneration device 5. Stop blowing when the SO2 concentration < 1 ppm. The blowing time is 2 hours, and the regeneration of the H2S desulfurizer is completed; 3 Meanwhile, collect the blown gas to obtain the blowing gas;

[0067]

[0068] (3) Preparation of mixed flue gas

[0069] Mix the blowing gas in step (2) and the flue gas containing NO / SO2 in the flue gas mixing tank 7, and react. Under the action of O3, NO is oxidized to NO2, and SO2 is oxidized to SO3 to obtain a mixed flue gas containing NO2 / SO3;

[0070] (4) Desulfurization and denitrification of mixed flue gas

[0071] Introduce the desulfurization and denitrification liquid in step (1) from the desulfurization and denitrification liquid storage tank 8 into the desulfurization and denitrification tower 9, and use the desulfurization and denitrification liquid circulation pump 10 to circulate and spray-wash the mixed flue gas containing NO2 / SO3 in step (3), and the following reactions occur:

[0072] 2Na2S + 8NO2 + 6NaOH = 8NaNO2 + Na2S2O3 + 3H2O;

[0073] 2NaOH + SO3 = Na2SO4 + H2O;

[0074] HCN + NaOH = NaCN + H2O;

[0075] After desulfurization and denitrification, the flue gas is led out by the flue gas fan 13 and discharged into the high altitude through the chimney;

[0076] Meanwhile, an on-line flue gas monitor 11 is used to monitor NO in the outlet flue gas. x , SO x concentrations, and a conductivity meter 12 is used to monitor the conductivity of the desulfurization and denitrification solution. When the conductivity ≥ 50 ms / cm 2 or the NO in the outlet flue gas x , SO x concentrations exceed the standard, the sewage drain valve is opened to discharge the ineffective desulfurization and denitrification solution into the sewage treatment station, and at the same time, fresh desulfurization and denitrification solution is replenished.

[0077] Example 2

[0078] An H2S desulfurizer for treating waste gas in a sewage treatment station of a semiconductor enterprise is prepared by loading 6% CuO on activated carbon fiber. 500 kg of saturated H2S desulfurizer is taken for regeneration.

[0079] A method for regenerating H2S desulfurizer combined with desulfurization and denitrification, as Figure 1 shown, specifically includes the following steps:

[0080] (1) Wet regeneration of H2S desulfurizer

[0081] A KOH solution with a mass concentration of 5% is prepared in the caustic alkali solution storage tank 1. 500 kg of saturated H2S desulfurizer is placed in the wet regeneration device 3, and 5 m 3 of KOH solution is added to the wet regeneration device 3 by the caustic alkali solution dosing pump 2. The H2S desulfurizer is soaked in the KOH solution at room temperature for 10 h until the KOH solution gradually changes from colorless and transparent to yellow, then filtered, and the soaking solution is passed into the desulfurization and denitrification solution storage tank 8 for temporary storage; then the tap water valve is opened, and the soaked H2S desulfurizer is washed 4 times in the wet regeneration device 3, with 5 m 3 of tap water flowing in each time, until the pH of the washing solution = 7.5, and the wet regenerated H2S desulfurizer is obtained; finally, the washing solution is passed into the desulfurization and denitrification solution storage tank 8 to be mixed with the soaking solution to obtain the desulfurization and denitrification solution;

[0082] (2) Dry regeneration of H2S desulfurizer

[0083] The wet regenerated H2S desulfurizer is transferred to the dry regeneration device 5, and air containing 1000 ppm ClO2 at 2000 m 3 / h is heated to 80 °C measured by the thermometer 6 by the electric heater 4 to blow the wet regenerated H2S desulfurizer. The blown gas at the outlet of the dry regeneration device 5 is detected by a hand-held SO2 detector. When the SO2 concentration < 1 ppm, the blowing is stopped, and the blowing time is 5 h, and the regeneration of the H2S desulfurizer is completed;

[0084] Meanwhile, the blown gas is collected to obtain the blown gas;

[0085] (3) Preparation of Mixed Flue Gas

[0086] Mix the purge gas in step (2) and the flue gas containing NO / SO2 in the flue gas mixing tank 7, and react. Under the action of ClO2, NO is oxidized to NO2, and SO2 is oxidized to SO3 to obtain a mixed flue gas containing NO2 / SO3;

[0087] (4) Desulfurization and Denitrification of Mixed Flue Gas

[0088] Introduce the desulfurization and denitrification liquid in step (1) from the desulfurization and denitrification liquid temporary storage tank 8 into the desulfurization and denitrification tower 9, and use the desulfurization and denitrification liquid circulation pump 10 to circulate and spray the mixed flue gas containing NO2 / SO3 in step (3) and the following reactions occur:

[0089] 2K2S + 8NO2 + 6KOH = 8KNO2 + K2S2O3 + 3H2O;

[0090] 2KOH + SO3 = K2SO4 + H2O;

[0091] KOH + HCl = KCl + H2O;

[0092] After desulfurization and denitrification, the flue gas is led out from the flue gas fan 13 and discharged into the air at high altitude through the chimney;

[0093] At the same time, use the on-line flue gas monitor 11 to monitor NO x 、SO x concentrations in the outlet flue gas, use the conductivity meter 12 to monitor the conductivity of the desulfurization and denitrification liquid. When the conductivity ≥ 50 ms / cm 2 or the NO x 、SO x concentrations in the outlet flue gas exceed the standard, open the sewage drain valve to discharge the ineffective desulfurization and denitrification liquid into the sewage station, and at the same time supplement fresh desulfurization and denitrification liquid.

[0094] Example 3

[0095] The H2S desulfurizer for treating the tail gas at the outlet of the H2S concentration tower in the low-temperature methanol washing system of a coking enterprise is prepared by loading 10% Fe2O3 on 13X molecular sieve. Take 2000 kg of saturated H2S desulfurizer for regeneration.

[0096] The method for regenerating the H2S desulfurizer and combining desulfurization and denitrification is as Figure 2 shown, and specifically includes the following steps:

[0097] (1) Wet Regeneration of H2S Desulfurizer

[0098] Prepare a KOH solution with a mass concentration of 20% in the caustic alkali solution storage tank 1. Place 2000 kg of saturated H2S desulfurizer in the wet regeneration device 3, and slowly spray 25 m 3 of the KOH solution in the wet regeneration device 3 using the caustic alkali solution dosing pump 2. Rinse the H2S desulfurizer at 50 °C for 1 h until the rinse liquid gradually changes from colorless and transparent to yellow. Then, transfer the rinse liquid to the desulfurization and denitrification liquid storage tank 8 for temporary storage. Next, open the tap water valve and wash the rinsed H2S desulfurizer in the wet regeneration device 3 three times, with 10 m 3 of tap water flowing in each time, until the pH of the wash liquid is 8.5, to obtain the regenerated H2S desulfurizer after wet regeneration. Finally, transfer the wash liquid to the desulfurization and denitrification liquid storage tank 8 to mix with the rinse liquid to obtain the desulfurization and denitrification liquid;

[0099] (2) Dry regeneration of H2S desulfurizer

[0100] Transfer the regenerated H2S desulfurizer after wet regeneration to the dry regeneration device 5. Heat the air containing 40% O2 at a flow rate of 6000 m 3 / h to 120 °C measured by the thermometer 6 using the electric heater 4, and blow the regenerated H2S desulfurizer after wet regeneration. Detect the blown gas at the outlet of the dry regeneration device 5 using a handheld SO2 detector. Stop blowing when the SO2 concentration < 1 ppm, and the blowing time is 10 h, and the regeneration of the H2S desulfurizer is completed;

[0101] Meanwhile, collect the blown gas to obtain the blown gas;

[0102] (3) Preparation of mixed flue gas

[0103] Mix the blown gas in step (2) and the flue gas containing NO / SO2 in the flue gas mixing tank 7, and react. Under the action of O2, NO is oxidized to NO2, and SO2 is oxidized to SO3 to obtain a mixed flue gas containing NO2 / SO3;

[0104] (4) Desulfurization and denitrification of mixed flue gas

[0105] Transfer the desulfurization and denitrification liquid in step (1) from the desulfurization and denitrification liquid storage tank 8 to the desulfurization and denitrification tower 9. Use the desulfurization and denitrification liquid circulation pump 10 to circulate and spray-wash the mixed flue gas containing NO2 / SO3 in step (3), and the following reactions occur:

[0106] 2K2S + 8NO2 + 6KOH = 8KNO2 + K2S2O3 + 3H2O;

[0107] 2KOH + SO3 = K2SO4 + H2O;

[0108] After desulfurization and denitrification, the flue gas is led out by the flue gas fan 13 and discharged high into the sky through the chimney;

[0109] Meanwhile, the NO in the outlet flue gas is monitored by the on-line flue gas monitor 11 x , SO x concentration, and the conductivity of the desulfurization and denitrification liquid is monitored by the conductivity meter 12. When the conductivity ≥ 50 ms / cm 2 or the NO in the outlet flue gas x , SO x concentration exceeds the standard, the sewage drainage valve is opened, and the ineffective desulfurization and denitrification liquid is introduced into the triple-effect evaporation system of the factory. After evaporation and concentration, a mixed salt of KOH, K2S, K2SO3, KNO3, K2S2O3, and K2SO4 is obtained. Since the amount of the mixed salt is small, it is sold as solid waste for treatment. At the same time, fresh desulfurization and denitrification liquid is supplemented in the desulfurization and denitrification tower 9.

[0110] Performance test

[0111] 1. Regeneration test of H2S desulfurizer

[0112] Take the regenerated H2S desulfurizer after the completion of step (2) in Examples 1-3 respectively, count and calculate its regeneration efficiency respectively, and test whether its activity is restored respectively.

[0113] Among them, the calculation formula of the regeneration efficiency is as follows:

[0114]

[0115] Among them,

[0116] η R represents the regeneration efficiency of the H2S desulfurizer, %;

[0117] M RS represents the sulfur capacity of the regenerated H2S desulfurizer for removing H2S, mg / g;

[0118] M S represents the sulfur capacity of the fresh H2S desulfurizer for removing H2S, mg / g.

[0119] The results are shown in Table 1.

[0120] Table 1 Results of the regeneration test of H2S desulfurizer

[0121]

[0122]

[0123] As can be seen from Table 1, by regenerating the deactivated H2S desulfurizer in Examples 1-3 respectively by the method of the present invention, it is found by testing after regeneration that the regeneration efficiency of the H2S desulfurizer is ≥ 99.0%.

[0124] The regenerated H2S desulfurizer is reused for H2S removal. The service time before the inactivation of the H2S desulfurizer is equivalent to that of the fresh H2S desulfurizer, and it can be considered that the activity of the H2S desulfurizer is well restored.

[0125] 2. Desulfurization and denitrification tests on flue gas mixtures

[0126] Take the flue gas containing NO / SO2 after dust removal and temperature reduction from each enterprise in step (3) of Examples 1 - 3 and the flue gas after desulfurization and denitrification treatment in step (4), and conduct component analysis respectively.

[0127] The results are shown in Table 2.

[0128] Table 2 Desulfurization and denitrification test results of flue gas mixtures

[0129]

[0130] As can be seen from Table 2, the NO x concentration in the raw flue gas of Examples 1 - 3 is in the range of 550 - 2000 mg / Nm 3 , and the SO2 concentration is in the range of 50 - 2200 mg / Nm 3 . After being treated by the methods of Examples 1 - 3 of the present invention, the NO x concentration ≤ 20 mg / Nm 3 , and the SO2 concentration ≤ 20 mg / Nm 3 . Moreover, for the small amount of acidic pollutants such as HCN and HCl existing in the flue gas, simultaneous purification is also carried out.

[0131] The flue gas mixtures after treatment in Examples 1 - 3 all meet the Integrated Emission Standard of Air Pollutants (GB 16297 - 1996), and Example 1 meets the minimum emission control indexes of sulfur dioxide (35 mg / Nm 3 ) and nitrogen oxides (50 mg / Nm 3 ) stipulated in the Opinions on Promoting the Implementation of Ultra - low Emissions in the Iron and Steel Industry jointly issued by the Ministry of Ecology and Environment and other five ministries and commissions in 2019.

[0132] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying, characterized in that, Specifically, it includes the following steps: (1) Wet regeneration of H2S desulfurizer Soak or wash the saturated H2S desulfurizer with caustic alkali solution, filter it, and then wash the H2S desulfurizer with water to obtain the H2S desulfurizer after wet regeneration; At the same time, mix the soaking liquid or washing liquid and the washing water to obtain the desulfurization and denitrification liquid; The H2S desulfurizer is a supported desulfurizer, including a carrier and an active component or an auxiliary agent; the carrier is activated carbon, activated carbon fiber, molecular sieve or zeolite, and the active component or auxiliary agent is a metal oxide; (2) Dry regeneration of H2S desulfurizer Transfer the H2S desulfurizer after wet regeneration to a dry regeneration device, and purge the H2S desulfurizer after wet regeneration with a gas containing an excessive amount of oxidant, and the H2S desulfurizer is regenerated; At the same time, collect the purged gas to obtain the purge gas; (3) Preparation of mixed flue gas Mix and react the purge gas in step (2) with the flue gas containing NO / SO2 to obtain a mixed flue gas containing NO2 / SO3; (4) Desulfurization and denitrification of mixed flue gas Spray and wash the mixed flue gas containing NO2 / SO3 in step (3) with the desulfurization and denitrification liquid in step (1), and the flue gas is discharged up to the standard.

2. The method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (1), the caustic alkali is NaOH or KOH; the mass concentration of the caustic alkali in the caustic alkali solution is 1% - 30%; the liquid-solid ratio of the caustic alkali solution to the saturated H2S desulfurizer is 5 - 50 L / kg.

3. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (1), the temperature of the soaking or washing is 20 - 100 °C, and the time is more than 30 min.

4. A method for regenerating a H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (1), wash until the pH of the washing water ≤ 9.

5. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (2), the oxidant is at least one of O3, O2, hydroxyl radical and ClO2.

6. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1 or 5, characterized in that, In step (2), the gas is at least one of air, flue gas containing NO x / SO x , clean flue gas, N2, and inert gas.

7. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying, according to claim 1, characterized in that In step (2), the temperature of the purging gas is 20~150°C; the space velocity of the purging is 2000~20000 h -1 , the time is ≥30 min; the purging is carried out until the SO2 concentration in the purging gas is reduced to less than 1 ppm.

8. A method for regenerating an H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (3), the reaction device is a flue gas mixing tank or a flue, and the time > 2 s.

9. A method for regenerating H2S desulfurizer and jointly desulfurizing and denitrifying according to claim 1, characterized in that, In step (4), the spray washing device is a vertical packed spray tower or a horizontal packed spray tower.

Images