NF-process total sulfur removal system for coke oven gas at normal temperature and normal pressure

Abstract

The utility model is applicable to the technical field of total sulfur removal of coal gas, and provides a system for removing total sulfur of coke oven gas by an NF method at normal temperature and normal pressure, which comprises a primary cooler, a precooling tower, an adsorption impurity removal module, an NF method hydrogen sulfide removal module, a hydrolysis conversion module and an NF method hydrogen sulfide and organic sulfur removal module, and the precooling tower is used for receiving the coke oven gas introduced by the primary cooler through an air blower; the precooling tower is used for controlling the temperature of the coke oven gas between 25 DEG C and 27 DEG C and washing and removing tar and naphthalene in the coke oven gas; the adsorption impurity removal module is used for receiving the coke oven gas treated by the precooling tower and removing naphthalene and tar; an NF method hydrogen sulfide removal module; the hydrolysis conversion module is used for hydrolyzing and converting organic sulfur into hydrogen sulfide at low temperature by an NF method; the NF-method hydrogen sulfide and organic sulfur removal module is used for removing hydrogen sulfide and organic sulfur by adopting an NFA desulfurization solvent; the total sulfur after desulfurization does not exceed 50 mg / Nm < 3 >; and it is ensured that SO2 in flue gas of a subsequent heating furnace meets the ultra-low emission requirement.

Description

TECHNICAL FIELD

[0001] The utility model relates to total sulfur removal technical field, more specifically, especially, it relates to coke oven gas NF method total sulfur removal system under normal temperature and normal pressure. BACKGROUND

[0002] The coke oven gas, blast furnace gas, coal gas, natural gas and cellulose raw gas of steel metallurgy, coal chemical industry, natural gas and cellulose chemical industry need the total sulfur removal industry of hydrogen sulfide and organic sulfur etc. 3 ; The organic sulfur content is generally 300-500 mg / m 3 ; The coke oven gas is used for heating, and the SO2 in flue gas is difficult to reach the requirement that less than 35 mg / m 3 .

[0003] At present, the removal process of hydrogen sulfide and organic sulfur in coke oven gas mainly has HPF method, vacuum potassium carbonate method and the like. 3 But the removal rate of organic sulfur is low, and the total sulfur in outlet gas is 120-300 mg / m 3 ; The hydrogen sulfulfide in outlet gas of vacuum potassium carbonate is about 200 mg / m 3 , and the removal rate of organic sulfur is low.

[0004] The total sulfur of coke oven gas used for heating is generally required to be less than 50 mg / m 3 ; The above method is difficult to meet the requirement. INVENTION CONTENTS

[0005] The utility model discloses a kind of total sulfur removal systems of coke oven gas under normal temperature and normal pressure, to solve the shortcomings in prior art: the total sulfur of coke oven gas used for heating is generally required to be less than 50 mg / m 3 ; The method of existing total sulfur removal technology is difficult to meet the requirement, and the total sulfur removal system of coke oven gas NF method under normal temperature and normal pressure is proposed.

[0006] Specific technical solutions are as follows: the total sulfur removal system of coke oven gas NF method under normal temperature and normal pressure, comprising:

[0007] Primary cooler;

[0008] Precooling tower, for the coke oven gas of primary cooler through blower introduction;The precooling tower is used to control the temperature of coke oven gas at 25-27 DEG C, and washes and removes tar and naphthalene in coke oven gas;

[0009] Adsorption impurity removal module, for receiving the coke oven gas after the pre-cooling tower treatment, for adsorption, further removing naphthalene and tar;

[0010] NF method desulfurization hydrogen sulfide module, for NFA desulfurizer selectively adsorbing hydrogen sulfide, with 20-50% mass concentration NFA desulfurization solvent absorbing H2S, organic acid and part of CO2 from gas;

[0011] Hydrolysis conversion module, for low-temperature hydrolysis conversion of organic sulfur into hydrogen sulfide by NF method, for low-temperature hydrolysis conversion of carbonyl sulfur and carbon disulfide into hydrogen sulfide;

[0012] NF method hydrogen sulfide and organic sulfur removal module, for hydrogen sulfide and organic sulfur removal by using NFA desulfurization solvent.

[0013] In the technical scheme of the utility model, the pre-cooling tower is further used for guiding the coke oven gas into the pre-cooled ammonia water, filtering the tar and ash in the coke oven gas through the PM membrane.

[0014] In the technical scheme of the utility model, the adsorption impurity removal module further removes naphthalene and tar through the adsorption of fiber microcrystal.

[0015] In the technical scheme of the utility model, the fiber microcrystal is replaced by activated carbon, and the activated carbon is used for removing naphthalene and tar.

[0016] In the technical scheme of the utility model, the adsorption impurity removal module is used for processing the tar concentration in the coke oven gas to 0-20 mg / m³ and naphthalene to not more than 200 mg / m³.

[0017] Another object of the utility model is to provide a coke oven gas NF method total sulfur removal process under normal temperature and pressure, comprising the following steps:

[0018] Step one, coke oven gas pre-cooling

[0019] S1, the primary cooler guides the coke oven gas into the pre-cooling tower through the air blower;

[0020] S2, the temperature of the coke oven gas is controlled at 25-27 DEG C;

[0021] S3, further removing the tar and naphthalene in the coke oven gas through washing;

[0022] S4, guiding the coke oven gas into the pre-cooled ammonia water, filtering the tar and ash through the PM membrane;

[0023] S5, the pre-cooling tower is provided with a steam purging process and a tar and naphthalene removal process, and the resistance of the pre-cooling tower is less than 1KPa;

[0024] Step two, adsorption impurity removal

[0025] Impurities including tar and naphthalene are removed by fiber microcrystal adsorption; after adsorption, the tar concentration in the coke oven gas is treated to 0-20 mg / m³ and the naphthalene is not more than 200 mg / m³;

[0026] Step three, NF method desulfurization hydrogen sulfide, for NFA desulfurizer selective adsorption of hydrogen sulfide, with mass concentration of 20-50% NFA desulfurization solvent aqueous solution from the gas chemical absorption H2S, organic acid and part of CO2;

[0027] Step four, carbonyl sulfur and carbon disulfide low temperature hydrolysis, for NF method organic sulfur low temperature hydrolysis into hydrogen sulfide, for carbonyl sulfur and carbon disulfide low temperature hydrolysis into hydrogen sulfide;

[0028] Step five, NF method hydrogen sulfide and organic sulfur removal, using NFA desulfurization solvent for carbonyl sulfur and carbon disulfide removal.

[0029] In the technical scheme of the utility model, in the step five NF method hydrogen sulfide and organic sulfur removal, carbonyl sulfur uses the NFA desulfurization solvent of adding activation absorbent.

[0030] In the technical scheme of the utility model, in the step five NF method hydrogen sulfide and organic sulfur removal, carbon disulfide removal includes physical absorption and catalytic hydrolysis.

[0031] In the technical scheme of the utility model, in the step five NF method hydrogen sulfide and organic sulfur removal, carbon disulfide removal still includes carbon disulfide and alcohol amine class material, a part generates reaction and generates xanthate class material, a part hydrolysis, still a part and amine complex absorption.

[0032] Compared with the prior art, the utility model can achieve:

[0033] 1, total sulfur after desulfurization is not more than 50 mg / Nm 3 ; Ensure that the SO2 in the subsequent heating furnace flue gas reaches the ultra-low emission requirement (the SO2 content in the flue gas is less than 35 mg / Nm 3 );

[0034] 2, in the desulfurization process, the chlorine ion content in the coal gas is greatly reduced, and the quality of the subsequent ammonium sulfate and crude benzene is effectively improved;

[0035] 3, in the low temperature hydrolysis, the coal gas is heat exchanged through the heat pipe technology, energy is fully recovered, and energy consumption is reduced;

[0036] 4, the low temperature hydrolysis catalyst of nonmetallic base is used, the service life is long, the hydrolysis rate is high, and the harmful impurities in the coal gas have no influence;

[0037] 5, the high-efficiency advanced compound NFA desulfurization liquid is used, the concentration is high, the corrosion is small, the equipment investment is low, and the energy consumption is low;

[0038] 6. High desulfurization efficiency, low total sulfur at outlet; desulfurization effect is not dependent on volatile ammonia content in coal gas, and production operation is more stable;

[0039] 7. The process does not produce sulfur foam, does not need filter pressing and molten sulfur, does not produce waste desulfurization liquid, does not need salt extraction or desulfurization liquid concentration incineration, does not need to treat the regeneration tail gas of conventional HPF, the production process is closed and odorless, environmentally friendly, fully automatic process control, greatly improves the working environment and reduces the labor burden;

[0040] 8. The remaining ammonia water entering the precooling tower is filtered by a PM membrane, which purifies the tar, dust and the like in the sprayed cooling ammonia water, and further optimizes the operation of the precooling tower;

[0041] 9. Desulfurization does not need ammonia source in coal gas, and the precooling tower does not need to control ammonia loss; the ammonia in this part is used for ammonium sulfate production, increasing enterprise benefits;

[0042] 10. Since NF method desulfurization also removes part of CO2 in coke oven gas, the calorific value of coke oven gas is increased. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 NF method coke oven gas total sulfur removal process diagram;

[0044] Figure 2 NFA desulfurizer mechanism diagram for improving carbonyl sulfur removal rate;

[0045] Figure 3 Mechanism diagram for low-temperature hydrolysis of carbonyl sulfur into hydrogen sulfide. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with specific examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0047] It should be noted that the NFA desulfurizer is MDEA composite alcohol amine.

[0048] Example 1, NF method total sulfur removal system of coke oven gas at room temperature and normal pressure, comprising:

[0049] Primary cooler;

[0050] A pre-cooling tower is used to receive the coke oven gas from the primary cooler through a blower. The pre-cooling tower is used to control the temperature of the coke oven gas at 25-27°C, and to remove tar and naphthalene from the coke oven gas through washing;

[0051] An adsorption impurity removal module is used to receive the coke oven gas after the pre-cooling tower treatment, for adsorption, further removal of naphthalene and tar;

[0052] An NF method hydrogen sulfide removal module is used to selectively adsorb hydrogen sulfide by using NFA desulfurization agent, to chemically absorb H2S, organic acid and part of CO2 from the gas by using a NFA desulfurization agent aqueous solution with a mass concentration of 20-50%;

[0053] A hydrolysis conversion module is used for low-temperature hydrolysis conversion of organic sulfur into hydrogen sulfide by using the NF method, for low-temperature hydrolysis conversion of carbonyl sulfur and carbon disulfide into hydrogen sulfide;

[0054] An NF method hydrogen sulfide and organic sulfur removal module is used to remove hydrogen sulfide and organic sulfur by using NFA desulfurization solvent.

[0055] Example 2: A coke oven gas NF method total sulfur removal process at normal temperature and pressure, including the following steps:

[0056] Step one: coke oven gas pre-cooling

[0057] S1: The primary cooler is used to guide the coke oven gas into the pre-cooling tower through a blower;

[0058] S2: The temperature of the coke oven gas is controlled at 25-27°C;

[0059] S3: Tar and naphthalene in the coke oven gas are further removed through washing;

[0060] S4: The coke oven gas is guided into pre-cooled ammonia water, and tar and ash are filtered through a PM membrane;

[0061] S5: The pre-cooling tower is provided with a steam purging process and a tar and naphthalene removal process, and the resistance of the pre-cooling tower is controlled to be less than 1 KPa;

[0062] Step two: adsorption impurity removal

[0063] Impurities including tar and naphthalene are removed through fiber microcrystal adsorption. After adsorption, the tar concentration in the coke oven gas is treated to be 0-20 mg / m³, and the naphthalene is not more than 200 mg / m³;

[0064] Step three: NF method hydrogen sulfide removal, selectively adsorbing hydrogen sulfide by using NFA desulfurization agent, chemically absorbing H2S, organic acid and part of CO2 from the gas by using a NFA desulfurization agent aqueous solution with a mass concentration of 20-50%;

[0065] Step four, low-temperature hydrolysis of carbonyl sulfur and carbon disulfide, which is converted into hydrogen sulfide by the NF method for low-temperature hydrolysis of carbonyl sulfur and carbon disulfide into hydrogen sulfide;

[0066] Step five, NF method hydrogen sulfide and organic sulfur removal, NFA desulfurization solvent is used for carbonyl sulfur and carbon disulfide removal.

[0067] Example 3,

[0068] The NF method total sulfur removal process of coke oven gas at normal temperature and pressure is described in detail in Figure 1 , which specifically includes the following steps:

[0069] (1) Pre-cooling of coke oven gas

[0070] Purpose of the pre-cooling tower:

[0071] 1) Control the temperature of the entering gas at 25-27°C to enter the next process, effectively maintaining the desulfurization efficiency;

[0072] 2) Further remove tar and naphthalene in the gas through washing;

[0073] 3) The ammonia water entering the pre-cooling is filtered through the PM membrane to remove tar and ash, improving the pre-cooling effect;

[0074] 4) The pre-cooling tower is provided with a steam purging process, a tar and naphthalene removal process, and the resistance of the stabilizing tower is less than 1 KPa.

[0075] Currently, there are two typical ways of gas pre-cooling, one is direct cooling (referred to as direct cooling) and the other is indirect cooling (referred to as indirect cooling) of the packed pre-cooling tower process. The indirect cooling pre-cooling process is that the gas passes through the pre-cooling tower from top to bottom and indirectly exchanges heat with the refrigerated water in the horizontal pipe to cool the gas to the required temperature. The direct cooling pre-cooling tower is that the gas passes through the packing in the tower from bottom to top and directly contacts with the low-temperature spraying liquid from top to bottom to cool the gas to the required temperature. Both processes can be used.

[0076] Adsorption of impurities

[0077] After pre-cooling, the tar, naphthalene and other impurities in the gas are further removed by adsorption. Adsorption can be through fiber microcrystalline adsorption or activated carbon adsorption.

[0078] After adsorption, the tar concentration in the coke oven gas is treated to 0-20 mg / m³, and the naphthalene is not more than 200 mg / m³; which can effectively reduce the filterate of the subsequent NF desulfurization liquid, greatly help to improve the desulfurization efficiency and save the NFA desulfurization reagent.

[0079] (3) Selective adsorption of hydrogen sulfide by NFA desulfurizer

[0080] Chemical absorption of H2S, organic acids and a portion of CO2 from gas with 20-50% (mass concentration) aqueous NFA desulfurizer.

[0081] R2NCH3 + H2S = R2NCH3 + HS (1)

[0082] R2NCOH3 + CO2 = R2NCH3 + HCO8 (2)

[0083] 2R2NH + H2S = (R2NH)2S (3)

[0084] (R2NH)2S + H2S = 2R2NH2S (4)

[0085] R2NH + H2O + CO2 = (R3NH)2CO3 (5)

[0086] (R3NH)2CO3 + H2O + CO2 = 2R3NH2CO3 (6)

[0087] Tertiary amines cannot react with CO2 to form carbamates, and give a much slower reaction rate than H2S with primary, secondary or tertiary amines. The reaction rate of CO2 with various tertiary amines is slower than that of primary or secondary amines in all cases. Therefore, the solvent for selective absorption of H2S is selected from tertiary amines.

[0088] NFA desulfurizer has a good selectivity or special solution for removing part of CO2 while maintaining H2S removal rate. It can meet the requirement of purifying gas with H2S less than 4 ppm.

[0089] (4) Carbonyl sulfide and carbon disulfide low-temperature hydrolysis

[0090] COS catalytic hydrolysis reaction is a widely used technology in coal gasification process, and the catalyst has been industrialized for many years. However, the purification of coke oven gas and the purification of blast furnace gas in steel industry have great differences in operation from the coal gasification process. In the coal gasification process, the operating pressure is usually 2,000-4,000 KPa, and the operating temperature is 250-300℃, while in the treatment of coke oven gas, the operating pressure and temperature are lower, which is difficult to meet the reaction requirements of general hydrolysis catalysts.

[0091] The composition of coke oven gas is also completely different from that of general coal gasification process, and HCl in coke oven gas has a great influence on the life and performance of COS hydrolysis catalyst. Therefore, the traditional catalyst is not suitable for coke oven gas, and a special catalyst suitable for the special conditions of coke oven gas operation needs to be developed to operate at low pressure, low temperature and high HCl content in the gas without poisoning.

[0092] Lower operating temperature is beneficial to balance the COS reaction, but the hydrolysis efficiency of COS is lower at low temperature. Therefore, in order to purify the content of COS in the gas as low as possible, a catalyst with high reaction rate at low temperature must be used.

[0093] When COS and water are adsorbed on the catalyst surface and close to each other, the hydrolysis reaction occurs on the catalyst surface to generate carbon dioxide and hydrogen sulfide (see Figure 3 ).

[0094] The technical challenge for traditional catalysts is that their catalytic function and activity depend on the additives. In the case of coke oven gas, these additive components such as Na or K will be occupied by HCl in the gas, which will quickly deactivate the catalyst.

[0095] Main features of COS-LTCTM low-temperature hydrolysis catalyst:

[0096] 1) Catalyst activation temperature 90°C;

[0097] 2) High conversion efficiency - up to 99.5% verified by actual project;

[0098] 3) High removal efficiency for both CS2 and COS;

[0099] 4) Low pressure drop;

[0100] 5) No need for regeneration;

[0101] 6) Hydrolysis efficiency greater than 90%.

[0102] (5) Conversion principle of organic sulfur such as carbonyl sulfur and carbon disulfide

[0103] NFA desulfurization solvent is used. Organic sulfur such as carbonyl sulfur and special formula components of the solvent undergo intermolecular addition reaction. This reaction is a reversible reaction that is relatively slow and the product is very unstable. A special treated metal packing catalyst is used to accelerate this reversible reaction process. When the product formed and other weak electrolytes in the solution come into contact, a multi-step decomposition reaction will immediately occur. The final product of the reaction is a special formula component and an inorganic weak acid product (such as CO2, H2S), which is then further subjected to alcohol amine H2S removal.

[0104] NF method desulfurization mechanism - the main reaction for COS removal is as follows:

[0105] COS conversion: amine solution with special formula is added as desulfurization solvent (see Figure 2). Organic sulfur such as carbonyl sulfur and special formula components of the solvent intermolecular addition reaction, the reaction is a reversible reaction is relatively slow and the product is very unstable, using a special treatment of metal catalyst to accelerate the reversible reaction process, when the product and other weak electrolytes in solution contact will immediately occur in a multi-step complex reaction, the final product of the reaction is a special formula components and inorganic weak acid products (such as CO2, H2S), COS catalytic hydrolysis and then absorption.

[0106] COS + RNH2 = RNH2 + COS - (zwitterion)

[0107] B + RNH2 + COS = RNHCOS - + BH - +

[0108] COS + R2NH = R2NH + COS - (zwitterion)

[0109] B + R2NH + COS = R2NHCOS - + BH - -

[0110] NF method of desulfurization mechanism-CS2 removal, including:

[0111] 1) physical dissolution;

[0112] 2) CS2 reaction removal;

[0113] 3) CS2 and alcohol amine, a part of the reaction to generate xanthate substances, a part of the hydrolysis, and a part of the amine complex absorption;

[0114] 4) CS2 catalytic hydrolysis;

[0115] 5) series hydrolysis reaction control steps:

[0116] CS2 + H2O → COS + H2S

[0117] COS + H2O → CO2 + H2S

[0118] The entire catalytic hydrolysis reaction macroscopic course can be expressed as:

[0119] CS2 → COS → H2S

[0120] Absorption purification principle of H2S and the like

[0121] ​​The alcohol amine H2S removal method is a typical absorption-regeneration reaction process, and the reaction mechanism is as follows: H2S and CO2 dissolved in water are slightly acidic, react with amine (weak alkaline) to generate salt which can be decomposed at high temperature. The main reactions are as follows:

[0122] 2R2NH+H2S → (R2NH)2S (1)

[0123] (R2NH)2S+H2S →2R2NH2S (2)

[0124] R2NH+H2O+CO2 →(R3NH)2CO3 (3)

[0125] (R3NH)2CO3+H2O +CO2 →2R3NH2CO3 (4)

[0126] Finally, it should be noted that the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application has been described in detail, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement, within the spirit and principles of the present application, any modification, equivalent replacement, improvement, etc., should be included within the scope of the present application.

Claims

1. A total sulfur removal system for coke oven gas using the NF method under ambient temperature and pressure, characterized in that, include: Primary cooler; The precooling tower is used to receive the coke oven gas introduced into the primary cooler by a blower. The precooling tower is used to control the temperature of coke oven gas between 25°C and 27°C, and to wash and remove tar and naphthalene from the coke oven gas. The adsorption and impurity removal module is used to receive coke oven gas after precooling tower treatment, and to adsorb it for further removal of naphthalene and tar. The NF method hydrogen sulfide removal module selectively adsorbs hydrogen sulfide using NFA desulfurizing agent, and chemically absorbs H2S, organic acids and part of CO2 from the gas using NFA desulfurization solvent with a mass concentration of 20-50%. The hydrolysis conversion module is used for the low-temperature hydrolysis of organic sulfur by the NF method to convert it into hydrogen sulfide, and is used for the low-temperature hydrolysis of carbonyl sulfur and carbon disulfide to convert them into hydrogen sulfide. The NF method hydrogen sulfide and organic sulfur removal module uses NFA desulfurization solvent for hydrogen sulfide and organic sulfur removal.

2. The NF method total sulfur removal system for coke oven gas under ambient temperature and pressure according to claim 1, characterized in that, The precooling tower is also used to introduce coke oven gas into precooled ammonia water and filter the tar and ash in the coke oven gas cooling ammonia water through a PM membrane.

3. The coke oven gas NF method total sulfur removal system under ambient temperature and pressure according to claim 1, characterized in that, The adsorption and impurity removal module further removes naphthalene and tar through the adsorption of fiber microcrystals.

4. The coke oven gas NF method total sulfur removal system under ambient temperature and pressure according to claim 3, characterized in that, The fiber microcrystals are replaced with activated carbon, which is used for naphthalene removal and tar removal.

5. The NF method total sulfur removal system for coke oven gas under ambient temperature and pressure according to claim 1, characterized in that, The adsorption and impurity removal module is used to treat the tar concentration in coke oven gas to 0-20 mg / m³ and naphthalene to no more than 200 mg / m³.

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