Process method for removing H2S and HCN from coke oven gas

Abstract

The invention provides a process method for removing H2S and HCN from coke oven gas, which comprises the following steps: A) contacting the coke oven gas with alkali liquor for gas-liquid reaction to obtain purified coke oven gas and absorption liquid; b) returning part of the absorption liquid to the gas-liquid reaction in the step A), and carrying out a synthetic reaction on the residual absorption liquid and sulfur under the condition of a catalyst; c) filtering the product obtained by the synthetic reaction, returning the solid-phase substance to the gas-liquid reaction in the step B), and evaporating and concentrating the filtrate; and D) extracting the solution obtained by evaporation and concentration with methanol, then carrying out solid-liquid separation, drying the solid phase to obtain a Na2S product, distilling the liquid phase to remove methanol, and then carrying out evaporative crystallization and centrifugal separation to obtain a NaSCN product. The process provided by the invention not only effectively reduces the pollution burden of the atmospheric environment, but also realizes high-value utilization of H2S and HCN, and has wide popularization and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of coke oven gas purification, and in particular relates to a process for removing H2S and HCN from coke oven gas. Background Art

[0002] At present, the purification technology of coke oven gas is mainly divided into two categories: dry process and wet process. The dry process uses solid absorbent to efficiently remove hydrogen sulfide from coal gas. Its advantages are simple operation and high desulfurization accuracy. However, its limitations are small processing scale and frequent replacement of desulfurizer. In contrast, the wet process uses liquid desulfurizer, which has the advantages of high desulfurization efficiency and sulfur recovery, but the operation is relatively cumbersome and is accompanied by the need to treat a large amount of waste liquid.

[0003] Despite this, the desulfurization of coke oven gas still faces multiple challenges. On the one hand, the waste liquid, waste gas and other pollutants generated in the desulfurization process need to be effectively treated, and the generated sulfur paste and other products are difficult to achieve high added value due to their poor quality; on the other hand, the HCN in the gas is not fully utilized, but is removed from the desulfurization liquid as a harmful component, which not only raises the operating cost, but also leads to unnecessary waste of resources. Summary of the invention

[0004] The object of the present invention is to provide a process for removing H2S and HCN from coke oven gas. The process of the present invention converts H2S and HCN into high-value products such as sodium sulfide and sodium thiocyanate. This process not only significantly reduces environmental pollution, but also successfully realizes the resource utilization of H2S and HCN.

[0005] A process for removing H2S and HCN from coke oven gas comprises the following steps:

[0006] A) contacting the coke oven gas with alkaline solution to carry out gas-liquid reaction to obtain purified coke oven gas and absorption liquid;

[0007] B) returning part of the absorption liquid to the gas-liquid reaction in step A), and performing a synthesis reaction between the remaining absorption liquid and sulfur under catalyst conditions;

[0008] The temperature of the synthesis reaction is 90-95°C, and the insulation time of the synthesis reaction is 90-120min;

[0009] The catalyst comprises one or more of benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is 1.5% to 2% of the mass of sulfur;

[0010] C) filtering the product obtained from the synthesis reaction, returning the solid phase material to the gas-liquid reaction in step B), and evaporating and concentrating the filtrate;

[0011] D) extracting the solution obtained by evaporation and concentration with methanol and then performing solid-liquid separation, the solid phase is dried to obtain the Na2S product, and the liquid phase is distilled to remove methanol and then evaporated, crystallized and centrifuged to obtain the NaSCN product.

[0012] Preferably, the alkali solution in step A) comprises NaOH, and the pH value of the alkali solution is 9-10.

[0013] Preferably, the temperature of the gas-liquid reaction in step A) is 30-35°C, the residence time of the gas-liquid reaction is 5-8s, and the liquid-gas ratio of the gas-liquid reaction is 10-20L / m 3 .

[0014] Preferably, the absorption liquid returned to the gas-liquid reaction in step A) accounts for 90-100% of the total absorption liquid.

[0015] Preferably, in the step B), the concentration of Na2S in the absorption liquid entering the synthesis reaction is controlled at 80-100 g / L, and the concentration of NaCN is controlled at 35-45 g / L.

[0016] Preferably, in step B), the molar ratio of sulfur to NaCN is (1.0-1.1):1.

[0017] Preferably, the condensed water produced by evaporation and concentration in step C) is returned to the alkali solution.

[0018] Preferably, in the step D), in the solution obtained by evaporation and concentration, the concentration of Na2S is controlled at 200-250 g / L, and the concentration of NaSCN is controlled at 140-180 g / L.

[0019] Preferably, in the step D), the mass concentration of methanol in the solution obtained by evaporation and concentration is 40-60%;

[0020] The temperature for solid-liquid separation in step D) is 75-85°C.

[0021] Preferably, in step D), the distillation temperature is 65-75°C;

[0022] In the step D), the evaporation crystallization temperature is 95 to 100° C., and the vacuum degree of the evaporation crystallization is -50 to -70 kPa.

[0023] The present invention provides a process for removing H2S and HCN from coke oven gas, comprising the following steps: A) contacting the coke oven gas with alkali solution to carry out gas-liquid reaction to obtain purified coke oven gas and absorption liquid; B) returning part of the absorption liquid to the gas-liquid reaction in step A), and carrying out synthesis reaction with the remaining absorption liquid and sulfur under catalyst conditions; the temperature of the synthesis reaction is 90-95°C, and the insulation time of the synthesis reaction is 90-120min; the catalyst comprises benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, One or more of ammonium bromide, tetradecyl trimethyl ammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is 1.5-2% of the mass of sulfur; C) filtering the product obtained by the synthesis reaction, returning the solid phase to the gas-liquid reaction in step B), and evaporating and concentrating the filtrate; D) extracting the solution obtained by evaporation and concentration with methanol and then performing solid-liquid separation, drying the solid phase to obtain the Na2S product, and distilling the liquid phase to remove methanol and then performing evaporation crystallization and centrifugal separation to obtain the NaSCN product. The process of the present invention first uses alkali liquid to absorb H2S and HCN in coal gas, and then converts these harmful substances into sodium sulfide and sodium thiocyanate products through a series of steps such as synthesis reaction, evaporation concentration, solid-liquid separation and distillation. This process not only effectively reduces the pollution burden of the atmospheric environment, but also realizes the high-value utilization of H2S and HCN. The method has the advantages of green environmental protection, resource conservation and low operating cost, and has broad prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 The process flow chart of the process for removing H2S and HCN from coke oven gas in the present invention is shown in FIG. DETAILED DESCRIPTION

[0026] The present invention provides a process for removing H2S and HCN from coke oven gas, comprising the following steps:

[0027] A) contacting the coke oven gas with alkaline solution to carry out gas-liquid reaction to obtain purified coke oven gas and absorption liquid;

[0028] B) returning part of the absorption liquid to the gas-liquid reaction in step A), and performing a synthesis reaction between the remaining absorption liquid and sulfur under catalyst conditions;

[0029] The temperature of the synthesis reaction is 90-95°C, and the insulation time of the synthesis reaction is 90-120min;

[0030] The catalyst comprises one or more of benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is 1.5-2% of the mass of sulfur;

[0031] C) filtering the product obtained from the synthesis reaction, returning the solid phase material to the gas-liquid reaction in step B), and evaporating and concentrating the filtrate;

[0032] D) extracting the solution obtained by evaporation and concentration with methanol and then performing solid-liquid separation, the solid phase is dried to obtain the Na2S product, and the liquid phase is distilled to remove methanol and then evaporated, crystallized and centrifuged to obtain the NaSCN product.

[0033] The process flow diagram of the present invention is as follows Figure 1 As shown, the present invention first contacts the coke oven gas with alkaline liquid to carry out gas-liquid reaction, absorbs H2S and HCN in the coke oven gas, obtains purified coke oven gas with H2S and HCN concentrations reaching the required level, and simultaneously obtains alkaline liquid, i.e., absorption liquid, which absorbs H2S and HCN.

[0034] In the present invention, the alkali solution is preferably sodium hydroxide, and the pH value of the alkali solution is preferably 9-10.

[0035] In the present invention, the temperature of the gas-liquid reaction is preferably 30-35°C, more preferably 31-34°C, such as 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, preferably a range value with any of the above values ​​as the upper or lower limit; the residence time of the gas-liquid reaction is preferably 5-8s, more preferably 6-7s; the liquid-gas ratio is preferably 10-20L / m 3 , more preferably 12 to 18 L / m 3 , such as 10L / m 3 , 11L / m 3 , 12L / m 3 , 13L / m 3 , 14L / m 3 , 15L / m 3 , 16L / m 3 , 17L / m 3 , 18L / m 3 , 19L / m 3 , 20L / m 3 , preferably a range value with any of the above numerical values ​​as the upper or lower limit.

[0036] After the gas-liquid absorption is completed, the present invention returns part of the obtained absorption liquid to the gas-liquid reaction in the previous step, and adds sulfur to the remaining absorption liquid to perform a synthesis reaction under catalyst conditions to generate a solution containing NaSCN.

[0037] In the present invention, in the absorption liquid entering the synthesis reaction, the concentration of Na2S is preferably controlled at 80-100 g / L, more preferably 85-95 g / L, such as 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, preferably with the above arbitrary numerical value as the upper or lower limit of the range value, the concentration of NaCN is preferably controlled at 35-45 g / L, more preferably 38-42 g / L, such as 35 g / L, 36 g / L, 37 g / L, 38 g / L, 39 g / L , 40g / L, 41g / L, 42g / L, 43g / L, 44g / L, 45g / L, preferably a range value with any of the above values ​​as the upper or lower limit; the mass of the absorption liquid returned to the gas-liquid reaction in the previous step accounts for 90-100% of the total mass of the absorption liquid, more preferably 92-98%, such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0038] In the present invention, the molar ratio of the added sulfur to the NaCN in the absorption liquid entering the synthesis reaction is preferably (1.0-1.1):1, more preferably (1.02-1.08):1, such as 1.0:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1, 1.1:1, preferably a range value with any of the above values ​​as the upper or lower limit.

[0039] In the present invention, the catalyst is preferably one or more of benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is preferably 1.5% to 2% of the mass of sulfur, such as 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0040] In the present invention, the temperature of the synthesis reaction is preferably 90-95°C, such as 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, preferably a range value with any of the above values ​​as the upper or lower limit; the insulation time of the synthesis reaction is preferably 90-120min, more preferably 100-110min.

[0041] After the synthesis reaction is completed, the obtained synthetic product is filtered, and the solid phase substance is mainly unreacted sulfur. The solid phase substance is returned to the above-mentioned gas-liquid reaction to improve the purity of the subsequent obtained product; the filtrate obtained by filtration is evaporated and concentrated, so that the Na2S concentration in the solution after evaporation and concentration is controlled at 200-250g / L, preferably 210-240g / L, such as 200g / L, 205g / L, 210g / L, 215g / L, 220g / L, 225g / L, 230g / L, 235g / L / L, 240g / L, 245g / L, 250g / L, preferably a range value with the above arbitrary numerical value as the upper or lower limit; the concentration of NaSCN in the solution after evaporation and concentration is preferably controlled at 140-180g / L, more preferably 150-170g / L, such as 140g / L, 145g / L, 150g / L, 155g / L, 160g / L, 165g / L, 170g / L, 175g / L, 180g / L, preferably a range value with the above arbitrary numerical value as the upper or lower limit.

[0042] In the present invention, the condensed water produced by the evaporation and concentration is returned to the alkali solution to maintain the water balance of the system.

[0043] After obtaining the evaporated concentrated solution, the present invention adds methanol therein to perform extraction, and after the extraction is completed, performs solid-liquid separation;

[0044] The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product;

[0045] The liquid phase obtained by solid-liquid separation is distilled, and the methanol obtained is collected and returned to the extraction and solid-liquid separation steps for recycling. The distilled liquid is evaporated, crystallized and centrifuged to obtain the sodium thiocyanate product.

[0046] In the present invention, the mass concentration of the extractant methanol in the solution obtained by the evaporation and concentration is preferably 40-60%, more preferably 45-55%, such as 40%, 45%, 50%, 55%, 60%, preferably a range value with any of the above values ​​as the upper or lower limit; the temperature of the solid-liquid separation is preferably 75-85°C, such as 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, preferably a range value with any of the above values ​​as the upper or lower limit.

[0047] In the present invention, the extractant methanol is recovered by distillation, and the distillation temperature is preferably 65-75°C, more preferably 68-72°C, such as 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, preferably a range value with any of the above values ​​as the upper or lower limit.

[0048] In the present invention, sodium thiocyanate is concentrated by evaporative crystallization, and the temperature of the evaporative crystallization is preferably 95-100°C, such as 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, and preferably a range value with any of the above numerical values ​​as the upper or lower limit; the vacuum degree of the evaporative crystallization is preferably -50 to -70 kPa, more preferably -55 to -65 kPa, such as -50 kPa, -55 kPa, -60 kPa, -65 kPa, -70 kPa, and preferably a range value with any of the above numerical values ​​as the upper or lower limit.

[0049] In the present invention, the centrifugal separation is a commonly used separation method in the art, and the present invention will not be described in detail here.

[0050] The present invention provides a process for removing H2S and HCN from coke oven gas, comprising the following steps: A) contacting the coke oven gas with alkali solution to carry out gas-liquid reaction to obtain purified coke oven gas and absorption liquid; B) returning part of the absorption liquid to the gas-liquid reaction in step A), and carrying out synthesis reaction with the remaining absorption liquid and sulfur under catalyst conditions; the temperature of the synthesis reaction is 90-95°C, and the insulation time of the synthesis reaction is 90-120min; the catalyst comprises benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, One or more of ammonium bromide, tetradecyl trimethyl ammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is 1.5-2% of the mass of sulfur; C) filtering the product obtained by the synthesis reaction, returning the solid phase to the gas-liquid reaction in step B), and evaporating and concentrating the filtrate; D) extracting the solution obtained by evaporation and concentration with methanol and then performing solid-liquid separation, drying the solid phase to obtain the Na2S product, and distilling the liquid phase to remove methanol and then performing evaporation crystallization and centrifugal separation to obtain the NaSCN product. The process of the present invention first uses alkali liquid to absorb H2S and HCN in coal gas, and then converts these harmful substances into sodium sulfide and sodium thiocyanate products through a series of steps such as synthesis reaction, evaporation concentration, solid-liquid separation and distillation. This process not only effectively reduces the pollution burden of the atmospheric environment, but also realizes the high-value utilization of H2S and HCN. The method has the advantages of green environmental protection, resource conservation and low operating cost, and has broad prospects for promotion and application.

[0051] In order to further illustrate the present invention, a process for removing H2S and HCN from coke oven gas provided by the present invention is described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3, HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 5 s, the reaction temperature was 35 °C, and the liquid-gas ratio was 10 L / m 3 Circulate and absorb until the Na2S concentration in the absorption liquid reaches 90g / L and the NaCN concentration reaches 40g / L. Take out part of the liquid after the reaction to react with sulfur. The reaction conditions are: temperature 90℃, insulation time 90min, sulfur addition molar amount n S :n NaCN The catalyst is 1.0, the amount of catalyst added is 1.5% of the mass of sulfur, and the catalyst is composed of 60% benzyltriethylammonium chloride + 40% benzyltrimethylammonium chloride. The solution after the synthetic reaction is filtered and evaporated and concentrated, and the solid phase obtained by filtration is returned to the synthetic reaction link. After evaporation and concentration, the concentration of Na2S in the solution reaches 200g / L, and the concentration of NaSCN reaches 145g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 40%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 75°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0054] Example 2

[0055] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 Circulate and absorb until the Na2S concentration in the absorption liquid reaches 90g / L and the NaCN concentration reaches 40g / L. Take out part of the liquid after the reaction to react with sulfur. The reaction conditions are: temperature 90℃, insulation time 90min, sulfur addition molar amount n S :n NaCNThe catalyst is 1.0, the amount of catalyst added is 1.5% of the mass of sulfur, and the catalyst is composed of 60% benzyltriethylammonium chloride + 40% benzyltrimethylammonium chloride. The solution after the synthetic reaction is filtered and evaporated and concentrated, and the solid phase obtained by filtration is returned to the synthetic reaction link. After evaporation and concentration, the concentration of Na2S in the solution reaches 200g / L, and the concentration of NaSCN reaches 145g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 40%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 75°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0056] Example 3

[0057] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 93°C, insulation time 95min, sulfur addition molar amount n S :n NaCN The catalyst is 1.05, the amount of catalyst added is 1.75% of the mass of sulfur, and the catalyst is composed of 40% hexadecyltrimethylammonium bromide + 30% tetradecyltrimethylammonium chloride + 30% 18-crown ether-6. The solution after the synthetic reaction is filtered and evaporated and concentrated, and the solid phase obtained by filtration is returned to the synthetic reaction link. After evaporation and concentration, the concentration of Na2S in the solution reaches 200g / L, and the concentration of NaSCN reaches 145g / L. The condensed water generated by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 40%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 75°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0058] Example 4

[0059] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 95°C, insulation time 100min, sulfur addition molar amount n S :n NaCN The catalyst is 1.1, the amount of catalyst added is 2% of the mass of sulfur, and the catalyst is composed of 30% benzyltriethylammonium chloride + 30% benzyltrimethylammonium chloride + 20% ethylene glycol + 20% binuclear phthalocyanine cobalt sodium sulfonate. The solution after the synthetic reaction is filtered and evaporated and concentrated, and the solid phase obtained by filtration is returned to the synthetic reaction link. After evaporation and concentration, the concentration of Na2S in the solution reaches 200g / L, and the concentration of NaSCN reaches 145g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 40%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 75°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0060] Example 5

[0061] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 95°C, insulation time 100min, sulfur addition molar amount n S :n NaCNThe catalyst is 1.1, the amount of catalyst added is 2% of the mass of sulfur, and the catalyst is composed of 30% benzyltriethylammonium chloride + 30% benzyltrimethylammonium chloride + 20% ethylene glycol + 20% binuclear phthalocyanine cobalt sodium sulfonate. The solution after the synthesis reaction is evaporated and concentrated. After evaporation and concentration, the concentration of Na2S in the solution reaches 250g / L, and the concentration of NaSCN reaches 180g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 50%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 80°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0062] Example 6

[0063] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 95°C, insulation time 100min, sulfur addition molar amount n S :n NaCN The catalyst is 1.1, the amount of catalyst added is 2% of the mass of sulfur, and the catalyst is composed of 30% benzyltriethylammonium chloride + 30% benzyltrimethylammonium chloride + 20% ethylene glycol + 20% binuclear phthalocyanine cobalt sodium sulfonate. The solution after the synthesis reaction is evaporated and concentrated. After evaporation and concentration, the concentration of Na2S in the solution reaches 250g / L, and the concentration of NaSCN reaches 180g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 60%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 85°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 65°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 95°C, and the vacuum degree is controlled at -50kpa.

[0064] Embodiment 7:

[0065] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 95°C, insulation time 100min, sulfur addition molar amount n S :n NaCN The catalyst is 1.1, the amount of catalyst added is 2% of the mass of sulfur, and the catalyst is composed of 30% benzyltriethylammonium chloride + 30% benzyltrimethylammonium chloride + 20% ethylene glycol + 20% binuclear phthalocyanine cobalt sodium sulfonate. The solution after the synthesis reaction is evaporated and concentrated. After evaporation and concentration, the concentration of Na2S in the solution reaches 250g / L, and the concentration of NaSCN reaches 180g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 50%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 80°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 70°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 100°C, and the vacuum degree is controlled at -60kpa.

[0066] Embodiment 8:

[0067] Gas flow 100m 3 / h, H2S concentration 2600mg / m 3 , HCN concentration 1500mg / m 3 The pH of the absorption liquid was 9.0, the residence time of the gas-liquid contact reaction was 7s, the reaction temperature was 30°C, and the liquid-gas ratio was 15L / m 3 The absorption was circulated until the Na2S concentration in the absorption liquid reached 90g / L and the NaCN concentration reached 40g / L. Part of the liquid after the reaction was taken out to react with sulfur. The reaction conditions were: temperature 95°C, insulation time 100min, sulfur addition molar amount n S :n NaCNThe catalyst is 1.1, the amount of catalyst added is 2% of the mass of sulfur, and the catalyst is composed of 30% benzyltriethylammonium chloride + 30% benzyltrimethylammonium chloride + 20% ethylene glycol + 20% binuclear phthalocyanine cobalt sodium sulfonate. The solution after the synthesis reaction is evaporated and concentrated. After evaporation and concentration, the concentration of Na2S in the solution reaches 250g / L, and the concentration of NaSCN reaches 180g / L. The condensed water produced by evaporation and concentration is returned to the absorption liquid. Methanol is added to the absorption liquid after evaporation and concentration, and the mass concentration of methanol in the absorption liquid is controlled at 50%. After extraction, solid-liquid separation is performed, and the temperature of solid-liquid separation is 80°C. The solid phase obtained by solid-liquid separation is dried to obtain a sodium sulfide product. The liquid phase obtained by solid-liquid separation is distilled, and the distillation temperature is controlled at 75°C. The methanol obtained by distillation is returned to the solid-liquid separation step for recycling. The liquid after distillation is evaporated, crystallized and centrifuged to obtain a sodium thiocyanate product. The evaporation and crystallization temperature is controlled at 100°C, and the vacuum degree is controlled at -70kpa.

[0068] Table 1 Process effect data in Examples 1 to 8

[0069]

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for removing H2S and HCN from coke oven gas, comprising the following steps: A) contacting the coke oven gas with alkaline solution to carry out gas-liquid reaction to obtain purified coke oven gas and absorption liquid; B) returning part of the absorption liquid to the gas-liquid reaction in step A), and performing a synthesis reaction between the remaining absorption liquid and sulfur under catalyst conditions; The temperature of the synthesis reaction is 90-95°C, and the insulation time of the synthesis reaction is 90-120min; The catalyst comprises one or more of benzyltriethylammonium chloride, benzyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, 18-crown ether-6, polyethylene glycol, binuclear sodium phthalocyanine cobalt sulfonate, and disodium anthraquinone disulfonate; the mass of the catalyst is 1.5% to 2% of the mass of sulfur; C) filtering the product obtained from the synthesis reaction, returning the solid phase material to the gas-liquid reaction in step B), and evaporating and concentrating the filtrate; D) extracting the solution obtained by evaporation and concentration with methanol and then performing solid-liquid separation, the solid phase is dried to obtain the Na2S product, and the liquid phase is distilled to remove methanol and then evaporated, crystallized and centrifuged to obtain the NaSCN product.

2. The process according to claim 1, characterized in that: The alkali solution in step A) comprises NaOH, and the pH value of the alkali solution is 9-10.

3. The process according to claim 1, characterized in that: The temperature of the gas-liquid reaction in step A) is 30-35° C., the residence time of the gas-liquid reaction is 5-8 s, and the liquid-gas ratio of the gas-liquid reaction is 10-20 L / m 3 .

4. The process according to claim 1, characterized in that: The absorption liquid returned to the gas-liquid reaction in step A) accounts for 90-100% of the total absorption liquid.

5. The process according to claim 1, characterized in that: In the step B), the concentration of Na2S in the absorption liquid entering the synthesis reaction is controlled at 80-100 g / L, and the concentration of NaCN is controlled at 35-45 g / L.

6. The process according to claim 5, characterized in that: In the step B), the molar ratio of sulfur to NaCN is (1.0-1.1):

1.

7. The process according to claim 1, characterized in that: The condensed water produced by evaporation and concentration in step C) is returned to the alkali solution.

8. The process according to claim 1, characterized in that: In the step D), in the solution obtained by evaporation and concentration, the concentration of Na2S is controlled at 200-250 g / L, and the concentration of NaSCN is controlled at 140-180 g / L.

9. The process according to claim 1, characterized in that: In the step D), the mass concentration of methanol in the solution obtained by evaporation and concentration is 40-60%; The temperature for solid-liquid separation in step D) is 75-85°C.

10. The process according to claim 1, characterized in that: In the step D), the distillation temperature is 65-75°C; In the step D), the evaporation crystallization temperature is 95 to 100° C., and the vacuum degree of the evaporation crystallization is -50 to -70 kPa.

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