Sulfur-tolerant shift operation method for raw gas

Abstract

The invention provides a raw gas sulfur-tolerant shift operation method, and relates to the technical field of raw gas shift processes. The sulfur-tolerant shift operation method mainly comprises the following steps: arranging a detoxification tank in front of a first shift furnace and a second shift furnace which are connected in series, filling magnesium aluminate spinel in the detoxification tank, filling a presulfurization catalyst in the first shift furnace and the second shift furnace, and setting the raw gas feeding amount, the system pressure and the water-gas ratio of the whole system and the temperatures of the first shift furnace and the second shift furnace to realize purification of the raw gas. The defects in the prior art are overcome, the CO content at the outlet of the shift converter can be effectively reduced, and the purification efficiency and effect are improved.

Description

Technical Field

[0001] The invention relates to the technical field of raw coal gas conversion process, and in particular to a raw coal gas sulfur-resistant conversion operation method. Background Art

[0002] The main task of the conversion process is to convert CO and H2O in the crude synthesis gas sent from the gasification process into H2 and CO2 through conversion reaction, and to recover heat in stages according to the different temperature ranges of the conversion gas and the crude synthesis gas.

[0003] According to the different catalysts used, the conversion is divided into sulfur-resistant conversion and non-sulfur-resistant conversion. For pressurized gasification using coal as raw material, since the pressure, temperature, water-gas ratio and sulfur content of the crude synthesis gas from gasification are relatively high, in order to avoid "hot and cold diseases" and reduce the energy consumption of the device, sulfur-resistant conversion is currently used both at home and abroad. The conversion adopts the sulfur-resistant conversion process, which can make full use of the saturated water vapor in the crude synthesis gas produced by the gasification section, avoid the demand for medium-pressure steam in the conversion process, and reduce the energy consumption of the device. At the same time, the Co-Mo catalyst has a catalytic effect on the conversion of organic sulfur into hydrogen sulfide, which can reduce the organic sulfur content in the decarbonized gas and improve the purification degree of the synthesis gas. In addition, according to the structure of the conversion furnace and the heat exchange method, it can also be divided into adiabatic conversion and isothermal conversion.

[0004] The conversion process mainly involves separating, heating, detoxifying and filtering the raw coal gas sent out by the gasification device, reacting CO with water vapor to produce hydrogen and carbon dioxide, and recovering by-product steam and waste heat. In the existing technology, the CO content of the final reaction is still relatively high, especially for a large amount of raw coal gas, which seriously affects the purification effect to a certain extent. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a raw coal gas sulfur-resistant conversion operation method, which can effectively reduce the CO content at the outlet of the conversion furnace and improve the purification efficiency and effect.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A crude coal gas sulfur-resistant shift operation method, the operation method comprising the following steps:

[0008] S1. Device setting: a detoxification tank is set before two series-connected converters, and the two series-connected converters are converter 1 and converter 2 respectively;

[0009] S2, filling the detoxification tank with magnesium aluminum spinel as a filter, and setting a presulfurization catalyst in the first and second transformers;

[0010] S3. During operation, the crude gas volume of the entire device is controlled to be 23517-95099.9Nm 3 / h, the system pressure is 3.18-3.6MPa, the water vapor / dry gas ratio is 0.63-0.87, and the temperature of the coal gas entering the first transformer is controlled to be 25℃ higher than the saturated steam temperature, and the inlet temperature of the second transformer is 220-260℃.

[0011] Preferably, in step S1, the first converter is connected in series with a first steam drum, and the second converter is connected in series with a second steam drum.

[0012] Preferably, the filter agent provided in the detoxification tank is strip-shaped magnesium-aluminum spinel particles with a diameter of 3.5-5.0 mm.

[0013] Preferably, the presulfurized catalyst is a Co-Mo based sulfur-resistant shift catalyst.

[0014] Preferably, the presulfurization catalysts arranged in the first transformer and the second transformer are both based on magnesium aluminum spinel as a carrier, and the CoS content in the presulfurization catalyst in the first transformer is ≥3.5wt%, the MoS2 content is ≥7.5wt%, and the balance is magnesium aluminum spinel; the CoS content in the presulfurization catalyst in the second transformer is ≥1.7wt%, the MoS2 content is ≥7.5wt%, and the balance is magnesium aluminum spinel.

[0015] Preferably, during operation, the highest point temperature of the catalyst bed of the first converter is controlled to be ≤400°C, the highest point temperature of the catalyst bed of the second converter is controlled to be ≤270°C, and the catalyst bed resistance of the first and second converters is both ≤20kPa.

[0016] Preferably, during operation, the first steam drum is controlled to discharge high-pressure steam, and the pressure of the high-pressure steam is 4.5 MPa, and the second steam drum is controlled to discharge medium-pressure steam, and the pressure of the medium-pressure steam is 1.15 MPa.

[0017] The present invention provides a crude coal gas sulfur-resistant shift operation method, which has the following advantages compared with the prior art:

[0018] The device connection and operation of the present invention can be used to adjust the gas volume 95099.90Nm 3 / h, the raw coal gas with a steam-gas ratio (steam / dry gas) of 0.87 is transformed to reduce the final CO to below 1.2% (dry basis, mol%);

[0019] (2) The present invention sets a detoxification tank in front of the purification device and sets magnesium aluminum spinel as a filter agent, which not only has high strength and strength stability, but also has high porosity, can effectively remove and adsorb impurities and poisons such as carbon black, tar and dust in the raw gas, protect the sulfur-resistant shift catalyst, and has a certain organic sulfur hydrolysis performance, which can greatly extend the service life of the subsequent CO sulfur-resistant shift catalyst;

[0020] (3) The catalyst of the present invention is a pre-sulfurized catalyst. It does not need to be separately sulfurized before use. It only needs to be heated to the operating temperature with nitrogen, so that it can be started without hydrogen. It does not need to be heated and then slowly sulfurized. The wide temperature and sulfur-resistant conversion catalyst can adapt to the changes in the amount and composition of raw gas under the above-mentioned working conditions. The catalyst cannot be pulverized during loading and use. The catalyst has no FT, methanation and carbon deposition reactions during the entire use period, and the catalyst is not crushed; the volume shrinkage of the catalyst is ≤2% under the operating pressure and temperature conditions;

[0021] (4) The present invention can effectively reduce the cooling capacity loss of low-temperature methanol washing, reduce the wastewater discharge of conversion, and reduce the emission of PSA tail gas by adjusting various parameters such as water-gas ratio and system pressure to optimize the outlet CO content. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the raw coal gas sulfur-resistant conversion system in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0024] Example:

[0025] 1. Raw materials:

[0026] 1. Magnesium aluminum spinel:

[0027] MgO+Al2O3 (m / m%): ≥90, in the form of strip-shaped particles with a diameter of 3.5-5.0 mm, a bulk density of 0.55-0.75 kg / L; crushing resistance ≥120 N / cm;

[0028] 2. Co-Mo series sulfur-resistant shift catalyst: with magnesium aluminum spinel (MgO+Al2O3) as carrier, the manufacturer is Qingdao Lianxin, the first transformer model is QDB-06-1(S) (CoS≥3.5wt%; MoS2: ≥7.5wt%; the balance is carrier), the second transformer model is QDB-06-2(S) (CoS≥1.7wt%; MoS2: ≥7.5wt%; the balance is carrier);

[0029] The operating temperature of the catalyst is 180-500°C; the operating pressure is 1.0-10.0 MPa; the dry gas space velocity is 1000-6000 h -1; Water-gas ratio: 0.2~2.0; Minimum H2S content in process gas: ≥200PPm (dry basis); Estimated service life (years): primary transformer ≥3 years; secondary transformer ≥5 years.

[0030] 2. Device settings: Figure 1 As shown, two parallel detoxification tanks are arranged before the first and second transformers connected in series, and the first and second transformers are connected to the first and second steam drums respectively, and a controllable heat transfer type of the steam drum is adopted to remove the heat and by-product steam in time, and the detoxification tank is filled with magnesium aluminum spinel, and the first and second transformers are filled with Co-Mo sulfur-resistant conversion catalysts.

[0031] 3. Operation:

[0032] Designed crude gas volume 95099.90Nm 3 / h; system pressure 100% load, 3.6MPa, water-gas ratio (steam / dry gas): 0.87, first drum V-03703, by-product 4.5Mpa steam, the highest point temperature of the first transformer bed layer ≤400℃, the outlet conversion gas CO<4.5% (dry basis, mol%), second drum V-03704 by-product 1.15Mpa steam, the highest point temperature of the second transformer bed layer ≤270℃, the outlet conversion gas CO<1.2% (dry basis, mol%);

[0033] Referring to the above operation process, adjust the raw gas volume, system pressure, water-gas ratio, the inlet temperature of the first transformer and the second transformer, and detect the CO content at the outlet of the first transformer and the outlet of the second transformer. The specific results are shown in the following table:

[0034]

[0035]

[0036] It can be seen from the above table that in actual use, the CO content at the outlet of the first transformer is ≤4.3%, and the CO content at the outlet of the second transformer is ≤0.9%, which has a good purification effect.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for sulfur-resistant shift operation of raw coal gas, characterized in that: The operation method comprises the following steps: S1. Device setting: a detoxification tank is set before two series-connected converters, and the two series-connected converters are converter 1 and converter 2 respectively; S2, filling the detoxification tank with magnesium aluminum spinel as a filter, and setting a presulfurization catalyst in the first and second transformers; S3. During operation, the crude gas volume of the entire device is controlled to be 23517-95099.9Nm 3 / h, the system pressure is 3.18-3.6MPa, the water vapor / dry gas ratio is 0.63-0.87, and the temperature of the coal gas entering the first transformer is controlled to be 25℃ higher than the saturated steam temperature, and the inlet temperature of the second transformer is 220-260℃.

2. The method for sulfur-resistant shift operation of raw coal gas according to claim 1, characterized in that: In step S1, the first converter is connected in series with a first steam drum, and the second converter is connected in series with a second steam drum.

3. The method for sulfur-resistant shift operation of raw coal gas according to claim 1, characterized in that: The filter medium provided in the detoxification tank is strip-shaped magnesium-aluminum spinel particles with a diameter of 3.5-5.0 mm.

4. The method for sulfur-resistant shift operation of raw coal gas according to claim 1, characterized in that: The presulfurized catalyst is a Co-Mo series sulfur-resistant shift catalyst.

5. The method for sulfur-resistant shift operation of raw coal gas according to claim 1, characterized in that: The presulfurization catalysts installed in the first transformer and the second transformer are both based on magnesium aluminum spinel as a carrier, and the CoS content in the presulfurization catalyst in the first transformer is ≥3.5wt%, the MoS2 content is ≥7.5wt%, and the balance is magnesium aluminum spinel; the CoS content in the presulfurization catalyst in the second transformer is ≥1.7wt%, the MoS2 content is ≥7.5wt%, and the balance is magnesium aluminum spinel.

6. The method for sulfur-resistant shift operation of raw coal gas according to claim 1, characterized in that: During operation, the highest point temperature of the catalyst bed of the first transformer is controlled to be ≤400℃, and the highest point temperature of the catalyst bed of the second transformer is controlled to be ≤270℃, and the catalyst bed resistance of the first and second transformers is ≤20kPa.

7. The method for sulfur-resistant shift operation of raw coal gas according to claim 2, characterized in that: During operation, the first steam drum is controlled to discharge high-pressure steam, and the pressure of the high-pressure steam is 4.5 MPa, and the second steam drum is controlled to discharge medium-pressure steam, and the pressure of the medium-pressure steam is 1.15 MPa.

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