Method for renewable adsorption desulfurization of coke oven gas

Abstract

The invention relates to the field of coke oven gas purification, and discloses a coke oven gas renewable adsorption desulfurization method which comprises the following steps: 1, directly introducing coke oven gas subjected to a chemical product purification and recovery section into a coke oven gas dry desulfurization tower; and 2, enabling the coke oven gas to sequentially pass through a pretreatment bed layer and a dry desulfurization agent bed layer, and obtaining clean coke oven gas after adsorption saturation. According to the method provided by the invention, high-efficiency desulfurization of the coke oven gas can be realized by using the dry desulfurization agent bed layer prepared from the active carbon with high adsorption capacity, so that hydrogen sulfide and other impurity components in the coke oven gas can be adsorbed and removed together, the adsorbent in the tower can be regenerated, the process flow is simplified, and the production cost is reduced. The equipment investment and the operation cost are effectively reduced, the long-period operation of the desulfurizing agent is ensured, the operation cost is low, and less sulfur-containing solid waste is generated.

Description

Technical Field

[0001] The invention relates to the field of coke oven gas purification, and in particular to a method for regenerative adsorption desulfurization of coke oven gas. Background Art

[0002] In modern industry, blast furnace ironmaking technology has always been the mainstream ironmaking method, and its output accounts for more than 95% of the world's total pig iron production. The indispensable raw material for blast furnace ironmaking is coke. The coking coal in the coke oven is isolated from the air and distilled to produce coke, while producing a large amount of coke oven gas as a by-product. Coke oven gas is a high calorific value (calorific value of 4000-4500 kcal) hydrogen-rich coal gas. It is a high-quality fuel and an important coal chemical raw material. According to production data, the gas production for each ton of coke produced is 400-450Nm 3 In 2021, China's coke production was 464 million tons. China's annual coke production basically maintains this level, and at the same time, a large amount of coke oven gas is produced as a by-product. After being purified by chemical products, nearly half of the coke oven gas is returned to the coke oven combustion chamber as fuel to heat the coke oven, and the other half needs to be further purified as fuel or raw material for chemical synthesis.

[0003] The volume fractions of the main components in coke oven gas are: H2 (55-60%), CH4 (23-27%), CO (5-8%), C m H n (2-4%), CO2 (1.5-3%), N2 (3-7%), O2 (0.3-0.8%). In addition, there are many impurities in coke oven gas, among which the main sulfur components are: H2S (6-8g / m 3 ), CS2 (0.3-0.5g / m 3 ) and COS (0.1-0.2g / m 3 ).

[0004] Before the use of coke oven gas, the essential purification process is desulfurization. The sulfur in coke oven gas will enter the atmosphere after the combustion of coke oven gas, which will cause environmental problems. In addition, the corrosion of sulfur on pipelines and the deactivation of catalysts in chemical synthesis reactions cannot be ignored. Therefore, before the use of coke oven gas, the coke oven gas must be desulfurized with different precisions according to its purpose. For the desulfurization and purification of coke oven gas, according to the desulfurization precision and the location of the desulfurization process, it can be theoretically divided into rough desulfurization, semi-fine desulfurization and fine desulfurization.

[0005] Generally, wet desulfurization is more commonly used for crude desulfurization of coke oven gas. Crude desulfurization can reduce the hydrogen sulfide in coke oven gas from 3-8g / m 3 Remove to 100mg / m 3 The following can also remove some organic sulfur components, while semi-fine desulfurization can further remove hydrogen sulfide in coke oven gas to 10mg / m3 Next, after semi-fine desulfurization, the coke oven gas is subjected to hydrogenation and hydrolysis and further fine desulfurization to remove the total sulfur content in the coke oven gas to 0.1×10 -6 mg / m 3 the following.

[0006] For the semi-fine desulfurization of coke oven gas, the commonly used dry desulfurizers in the industry include activated carbon, iron oxide, etc., and these two desulfurizers have a common disadvantage, that is, high regeneration energy consumption. For example, ordinary activated carbon regeneration requires a high temperature of 450°C to regenerate, and the regeneration stability is poor. At high temperatures, the elemental sulfur is taken out and the pore structure of the activated carbon is destroyed, resulting in a decrease in the desulfurization efficiency of the regenerated activated carbon, which requires frequent replacement of the desulfurizer, resulting in an increase in operating costs. For example, iron oxide also requires a high temperature of 400-700°C to regenerate. For cost considerations, these desulfurizers with high regeneration energy consumption are regarded as one-time desulfurizers in actual industrial applications, that is, the desulfurizer is directly replaced after reaching the sulfur capacity, and the regeneration problem is not considered, which leads to an increase in sulfur-containing solid waste and an increase in solid waste treatment costs.

[0007] The purpose of the present invention is to reduce the operating cost of the semi-fine desulfurization process, achieve high-efficiency desulfurization of coke oven gas, and ensure the long-term operation of desulfurization consumables (desulfurizer). The present invention proposes a regenerative adsorption desulfurization method for coke oven gas. After the coke oven gasification and purification process, the hydrogen sulfide content in the coke oven gas is 100 mg / m 3 After the coke oven gas passes through the desulfurization tower, the hydrogen sulfide in the coke oven gas is physically adsorbed and removed to 10 mg / m 3 After saturation of adsorption, the adsorbent is thermally regenerated by using hot purified gas at 300°C. The adsorbent capable of adsorbing tar, naphthalene and benzene is simultaneously filled in the adsorption tower to further purify the coke oven gas. The thermal regeneration of the adsorbent capable of adsorbing tar is stable at 300°C, and the regeneration temperature of the adsorbent capable of adsorbing naphthalene and benzene is above 180°C. Therefore, when the regeneration temperature of 300°C is used, the tar, naphthalene and benzene can be taken out of the adsorption tower at the same time as the desulfurizer bed is regenerated, and the corresponding adsorbent can be regenerated. Summary of the invention

[0008] The purpose of the present invention is to provide a method for regenerative adsorption desulfurization of coke oven gas, effectively reduce the operating cost of the semi-fine desulfurization process, achieve high-efficiency desulfurization of coke oven gas, ensure long-term operation of the desulfurizer, and have low operating costs and less sulfur-containing solid waste.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A method for regenerative adsorption desulfurization of coke oven gas comprises the following steps:

[0011] The first step is to directly connect the coke oven gas after the chemical product purification and recovery section to the coke oven gas dry desulfurization tower;

[0012] In the second step, the coke oven gas is passed through the pretreatment bed and the dry desulfurization agent bed in sequence. After adsorption saturation, clean coke oven gas can be obtained.

[0013] Furthermore, the coke oven gas coming from the chemical product purification and recovery section has a pressure of 10-20 KPa and a temperature of 30-45°C.

[0014] Furthermore, after the dry desulfurizer is saturated with adsorption, a small amount of clean coke oven gas at 300-320°C is used to thermally regenerate the adsorption tower, and the pretreatment bed is regenerated at this temperature while the dry desulfurizer is regenerated.

[0015] Furthermore, the pretreatment bed is a combination of one or more of activated alumina, low-quality activated carbon, coke, dechlorination agent, etc.

[0016] Furthermore, the dry desulfurization agent bed is prepared from activated carbon with high adsorption capacity.

[0017] In this scheme, in the adsorption state, the coke oven gas is led out through the chemical product recovery section and enters the desulfurization tower from the bottom of the adsorption tower through the pipeline. A pretreatment adsorption and impurity removal bed is set in the tower to adsorb impurities such as tar, naphthalene, benzene, etc. remaining in the coke oven gas. Then, after passing through the desulfurization agent bed of the desulphurization method, the hydrogen sulfide in the coke oven gas is physically adsorbed and removed. After a period of adsorption, it reaches the sulfur capacity of the desulfurizer and switches to the regeneration state of the desulfurization tower. The purified coke oven gas enters the subsequent section.

[0018] In the regeneration state, a small amount of clean coke oven gas is drawn from the outlet of the desulfurization tower, heated by the heater, and then passed into the desulfurization tower from the top of the tower through a pipeline. The hydrogen sulfide in the desulfurizer in the tower and the tar, naphthalene and benzene adsorbed by the pretreatment bed are desorbed at the same time and taken out of the tower together with the analysis gas, and sent to the inlet of the wet desulfurization tower in the chemical product recovery section through a pipeline.

[0019] Furthermore, the adsorption of hydrogen sulfide by the dry desulfurization agent bed is physical adsorption, and when the temperature reaches 250-300°C, the adsorbed hydrogen sulfide will desorb from the adsorbent.

[0020] Furthermore, the desorption temperature of the adsorbed tar from the adsorbent is about 300-310°C, and the adsorbed naphthalene and benzene can be desorbed from the adsorbent at 180-185°C.

[0021] Furthermore, the method for preparing the high adsorption capacity activated carbon comprises the following steps:

[0022] S1: Place bacterial cellulose in deionized water, stir thoroughly for 0.5-1h, then add 2-chloroethylamine and a catalyst, heat to 55-60°C and continue stirring for 3-5h, collect the product after rotary evaporation, and obtain ammoniated bacterial cellulose;

[0023] S2: placing the ammoniated bacterial cellulose in deionized water, adding 1,3-phenylenediboric acid after sufficient stirring, continuing stirring at a rate of 300-350 r / min for 5-8 hours, and collecting the product by vacuum distillation to obtain a desulfurization agent precursor;

[0024] S3: The desulfurizer precursor and the porogen are fully mixed, placed in a porcelain boat, nitrogen is introduced, and the mixture is placed in a tubular furnace and heated to 550-600°C. After keeping the temperature for 30-45 minutes, the mixture is cooled to room temperature to obtain a carbonized product. After washing, drying and grinding, activated carbon with high adsorption capacity is obtained.

[0025] Furthermore, in step S1, the catalyst is pyridine.

[0026] Furthermore, in step S3, the porogen is ammonium chloride.

[0027] In this scheme, under the action of a catalyst, the hydroxyl group in the bacterial cellulose structure undergoes a substitution reaction with the active chlorine in the 2-chloroethylamine structure to obtain aminated bacterial cellulose, and then under sufficient stirring, the amino group in the aminated bacterial cellulose structure interacts with the boric acid group in the 1,3-phenylenediboronic acid structure to obtain a cross-linked desulfurizer precursor, and then under high temperature, the desulfurizer precursor is carbonized to obtain a high adsorption capacity activated carbon doped with nitrogen and boron elements. There is a difference in electronegativity between the nitrogen atom and the carbon atom in this type of high adsorption capacity activated carbon, which can introduce additional active sites on the carbon skeleton to enhance the absorption of hydrogen sulfide. The boron atom contributes electrons in the carbon skeleton, and the obtained boron-doped porous carbon interacts with the electron acceptor hydrogen sulfide, enhancing the adsorption capacity of the high adsorption capacity activated carbon for hydrogen sulfide. At the same time, the doping of the boron element can also enhance the stability of the high adsorption capacity activated carbon, so that it can play a better desulfurization effect.

[0028] Beneficial effects of the present invention:

[0029] The method provided by the present invention can adsorb and remove hydrogen sulfide and other impurity components in coke oven gas together, and the adsorbent in the tower can be regenerated, simplifying the process flow. Multiple regeneration of the adsorbent can reduce the one-time equipment investment and operating costs. In addition, the present invention can further purify the impurity components such as tar, naphthalene, benzene, chlorine, etc. in the coke oven gas by setting a pretreatment bed layer, and the adsorbent loaded at the bottom of the adsorption tower can reduce the loss of the desulfurization adsorbent while increasing the purity of the coke oven gas. By setting a dry desulfurization agent bed prepared from high adsorption capacity activated carbon, high-efficiency desulfurization of coke oven gas can be achieved, the operating cost of the semi-fine desulfurization process can be effectively reduced, and the long-term operation of the desulfurizer is guaranteed, and the operating cost is low, and less sulfur-containing solid waste is generated.

[0030] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0032] Figure 1 This is the UV spectrum of ammoniated bacterial cellulose and desulfurization agent precursor in the embodiment of the present invention;

[0033] Figure 2 This is a scanning electron microscope image of the activated carbon with high adsorption capacity in the embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the process of regenerative adsorption desulfurization and impurity removal of coke oven gas according to the present invention;

[0035] Figure 4 It is a schematic diagram of the internal filling of the coke oven gas adsorption desulfurization tower of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The preparation method of the high adsorption capacity activated carbon in the following examples and comparative examples of the present invention is:

[0038] S1: 3 g of bacterial cellulose was placed in 80 ml of deionized water, and after being stirred for 0.5 h, 2 g of 2-chloroethylamine and 0.02 g of pyridine were added, and the temperature was raised to 55 °C and stirred for 3 h. The product was collected after rotary evaporation to obtain ammoniated bacterial cellulose;

[0039] S2: 3.5 g of ammoniated bacterial cellulose was placed in 100 ml of deionized water, and 3 g of 1,3-phenylenediboric acid was added after sufficient stirring. The mixture was stirred at a rate of 300 r / min for 5 h, and the product was collected by vacuum distillation to obtain a desulfurization agent precursor.

[0040] The ammoniated bacterial cellulose and the desulfurization agent precursor were tested using the Evolut ion300 Thermo Fisher UV spectrophotometer. Figure 1 It can be seen that there is no obvious absorption peak at 240-400nm in the UV spectrum of aminated bacterial cellulose; in the UV spectrum of the desulfurizer precursor, an absorption peak of the benzene ring appears at 255nm. The appearance of the benzene ring absorption peak indicates that the amino group in the structure of aminated bacterial cellulose interacts with the boric acid group in the structure of 1,3-phenylenediboronic acid.

[0041] S3: 5 g of the desulfurizer precursor was fully mixed with 2.6 g of ammonium chloride, placed in a porcelain boat, introduced with nitrogen, placed in a tubular furnace and heated to 550°C. After keeping warm for 30 minutes, it was cooled to room temperature to obtain a carbonized product. After washing, drying and grinding, activated carbon with high adsorption capacity was obtained.

[0042] The morphology of high adsorption capacity activated carbon was tested using a S-4800 Hitach I scanning electron microscope. Figure 2 It can be seen that this type of high adsorption capacity activated carbon has a rich pore structure because the ammoniated bacterial cellulose interacts with 1,3-phenylenediboric acid, which gives it a rich network structure. After high-temperature carbonization and etching with ammonium chloride, a rich pore structure is formed in the activated carbon.

[0043] Example 1

[0044] The coke oven gas from a coking plant through the chemical product purification section has a pressure of 10KPa, a temperature of 30°C, and a coke oven gas flow rate of 60000Nm 3 / h, containing H2S concentration 20mg / Nm 3 , containing tar concentration 20mg / Nm 3 , containing naphthalene concentration 200mg / Nm 3 It is drawn out from the chemical product purification section and introduced into the desulfurization tower from the bottom. It first enters the pretreatment bed layer at the bottom which is filled with a mixture of activated carbon, coke and alumina, and then enters the dry desulfurization agent bed layer. The desulfurization agent is activated carbon with high adsorption capacity.

[0045] After the desulfurization tower is saturated with adsorption, a small amount of clean coke oven gas is heated to about 300°C by a heater and the bed layer in the tower is thermally regenerated from the top of the desulfurization tower. After heating to 300°C, it is maintained for 1 hour and then cold-blown. The regeneration stability is good, and the sulfur concentration and impurity content of the coke oven gas at the outlet of the desulfurization tower meet the requirements.

[0046] The final H2S concentration at the outlet of the desulfurization tower is less than 10mg / Nm 3 , tar<5mg / Nm 3 , naphthalene<50mg / Nm 3 The desulfurization and de-impurity effects meet the design requirements.

[0047] Comparative Example 1

[0048] The coke oven gas from a coking plant through the chemical product purification section has a pressure of 10KPa, a temperature of 30°C, and a coke oven gas flow rate of 60000Nm 3 / h, containing H2S concentration 20mg / Nm 3 , containing tar concentration 20mg / Nm 3 , containing naphthalene concentration 200mg / Nm 3 It is drawn out from the chemical product purification section and introduced into the desulfurization tower from the bottom. It first enters the pretreatment bed layer at the bottom which is filled with a mixture of activated carbon, coke and alumina, and then enters the dry desulfurization agent bed layer. The desulfurization agent is commercially available activated carbon.

[0049] After the desulfurization tower is saturated with adsorption, a small amount of clean coke oven gas is heated to about 300°C by a heater and the bed layer in the tower is thermally regenerated from the top of the desulfurization tower. After heating to 300°C, it is maintained for 1 hour and then cold-blown. The regeneration stability is good, and the sulfur concentration and impurity content of the coke oven gas at the outlet of the desulfurization tower meet the requirements.

[0050] The final H2S concentration at the outlet of the desulfurization tower is less than 20mg / Nm 3 , tar<5mg / Nm 3 , naphthalene<50mg / Nm 3 The impurity removal effect meets the design requirements, but the sulfur removal effect is poor, which is due to the limited adsorption capacity of commercially available activated carbon.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0052] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for regenerative adsorption desulfurization of coke oven gas, characterized in that: The following steps are involved: The first step is to directly connect the coke oven gas after the chemical product purification and recovery section to the coke oven gas dry desulfurization tower; In the second step, the coke oven gas is passed through the pretreatment bed and the dry desulfurization agent bed in sequence. After adsorption saturation, clean coke oven gas can be obtained.

2. The method for regenerative adsorption desulfurization of coke oven gas according to claim 1, characterized in that: The coke oven gas coming from the chemical product purification and recovery section has a pressure of 10-20 KPa and a temperature of 30-45°C.

3. The method for regenerative adsorption desulfurization of coke oven gas according to claim 1, characterized in that: The dry desulfurization agent bed layer and the pretreatment bed layer are filled in layers, and the pretreatment bed layer is at the bottom of the desulfurization tower.

4. The method for regenerative adsorption desulfurization of coke oven gas according to claim 1, characterized in that: After the dry desulfurizer is saturated with adsorption, a small amount of clean coke oven gas at 300-320° C. is used to thermally regenerate the desulfurization tower, and the pretreatment bed is regenerated at this temperature while the dry desulfurizer is regenerated.

5. The method for regenerative adsorption desulfurization of coke oven gas according to claim 1, characterized in that: The pretreatment bed is a combination of one or more of activated alumina, low-quality activated carbon, coke, dechlorination agent, etc.

6. The method for regenerative adsorption desulfurization of coke oven gas according to claim 1, characterized in that: The dry desulfurization agent bed is prepared from activated carbon with high adsorption capacity.

7. The method for regenerative adsorption desulfurization of coke oven gas according to claim 6, characterized in that: The method for preparing the high adsorption capacity activated carbon comprises the following steps: S1: Place bacterial cellulose in deionized water, stir thoroughly for 0.5-1h, then add 2-chloroethylamine and a catalyst, heat to 55-60°C and continue stirring for 3-5h, collect the product after rotary evaporation, and obtain ammoniated bacterial cellulose; S2: placing the ammoniated bacterial cellulose in deionized water, adding 1,3-phenylenediboric acid after sufficient stirring, continuing stirring at a rate of 300-350 r / min for 5-8 hours, and collecting the product by vacuum distillation to obtain a desulfurization agent precursor; S3: The desulfurizer precursor and the porogen are fully mixed, placed in a porcelain boat, nitrogen is introduced, and the mixture is placed in a tubular furnace and heated to 550-600°C. After keeping the temperature for 30-45 minutes, the mixture is cooled to room temperature to obtain a carbonized product. After washing, drying and grinding, activated carbon with high adsorption capacity is obtained.

8. The method for regenerative adsorption desulfurization of coke oven gas according to claim 7, characterized in that: In step S1, the catalyst is pyridine.

9. The method for regenerative adsorption desulfurization of coke oven gas according to claim 7, characterized in that: In step S3, the porogen is ammonium chloride.

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