Mixed gas purification device

Abstract

The utility model relates to the field of multi-step methods for purifying coal gas, in particular to a mixed coal gas purifying device. The mixed gas purification device comprises a deacidification device (1) and is characterized by further comprising a first gas mixing device (2), a pressurizing machine (3), a first cooler (4), a temperature swing adsorption pretreatment tower (5), a heater (6), a hydrolysis tower (7), a second cooler (8), a fine desulfurization tower (9) and a second gas mixing device (10). The desulfurization device is high in desulfurization efficiency and environment-friendly.

Description

Technical Field

[0001] The utility model relates to the field of a multi-step method for purifying coal gas, in particular to a mixed coal gas purification device. Background Art

[0002] At present, the steel mill rolling process generally uses a mixture of coke oven gas, blast furnace gas and converter gas produced as by-products of the main steel production processes such as coking, ironmaking and steelmaking as fuel for the heat treatment furnace. This can make full use of the thermal energy of the gas, reduce gas emissions, and reduce pollution to the environment. It is an effective means of energy conservation and emission reduction. However, the sulfur components such as hydrogen sulfide (H2S) and carbonyl sulfide (COS), CS2, thiophene, etc. contained in the gas are burned as SO2 in the flue gas and discharged into the atmosphere to cause pollution. Flue gas that has not been purified cannot meet the SO2 concentration limit of ≤50mg / m3 for flue gas (baseline oxygen content of dry flue gas is 8%) in the "Opinions on Promoting the Implementation of Ultra-low Emissions in the Steel Industry" 3 requirements.

[0003] In this regard, the traditional environmental protection transformation technology route is post-combustion desulfurization, installing a desulfurization device in the flue gas discharge flue of the furnace, and using calcium method (limestone / gypsum as desulfurizer), magnesium method (magnesium oxide as desulfurizer), ammonia method (synthetic ammonia as desulfurizer), sodium method (sodium hydroxide as desulfurizer) and other processes for desulfurization. However, the amount of flue gas doubles after combustion, and large steel companies often have dozens of steel rolling heat treatment furnaces with scattered locations. If a desulfurization device is installed in the flue of each heating furnace, there are problems such as a large amount of flue gas to be purified, a large number of flue gas desulfurization devices, high investment, difficult management, tight location in the general plan of the old factory, and difficulty in implementation due to limited sites.

[0004] In recent years, the steel enterprises have explored and applied the technology route of desulfurization of coke oven gas or blast furnace gas before combustion. Various types of fine desulfurization devices such as microcrystals / DDS / iron oxide, activated carbon / hydrolysis catalytic conversion are installed at the outlet of the gas refining system of the coking unit, which is the source of coke oven gas; organic sulfur hydrolysis devices and hydrogen sulfide removal devices are installed before and after the blast furnace TRT, which is the source of blast furnace gas. This reduces the sulfur content of coke oven gas and blast furnace gas sent out of the coking unit and blast furnace unit and entering the gas pipeline network of the whole plant. In this way, the back-end process of using these purified gases can achieve ultra-low emission standards. Taking a large steel joint venture with an annual steel output of 11 million tons / a as an example, the average calendar hour generation of blast furnace gas is about 2.04 million standard m 3 / h, and the average calendar hourly generation of coke oven gas is about 230,000 standard m 3 / h. If these coal gases are desulfurized at the source, the gas processing volume is 2.27 million standard m 3 / h, but there are also problems such as large amount of gas to be purified, high investment and operating costs, and desulfurization at the source of the blast furnace affecting the TRT power generation output.

[0005] In the past decade, as my country's restrictions on air pollutant emissions have become increasingly stringent, many steel companies have built blast furnace hot blast stove flue gas desulfurization, sintering flue gas desulfurization equipment, boiler flue gas desulfurization, self-provided power plant flue gas desulfurization equipment, etc. through environmental protection transformation. The main users of steel plant gas - iron-making blast furnace hot blast stoves, sintering, coking coke oven chimneys, boilers, self-provided power plants and other processes have achieved ultra-low emission standards; cold rolling heating furnaces and annealing furnaces are also able to meet the standards because the current ultra-low emission standards stipulate that the baseline oxygen content of dry flue gas is 15%; only the problem of non-compliance with emissions from steel rolling (hot rolling) heat treatment furnaces is more prominent because it is difficult to solve. The amount of blast furnace gas and coke oven gas used by these users only accounts for about 7% to 10% of the total amount.

[0006] The sulfur component brought by blast furnace gas in the coal gas used for hot rolling accounts for about 30% of the total sulfur. Therefore, it is impossible to achieve ultra-low emission standards by only implementing fine desulfurization of blast furnace gas.

[0007] The fine desulfurization of coke oven gas requires the organic sulfur components in the coke oven gas to react with hydrogen under high temperature (about 300°C) and high pressure (about 3.0MPa) conditions under the action of a catalyst, and then be fully converted into hydrogen sulfide for removal. This method has a high desulfurization rate, but high energy consumption. It is mostly used in coal chemical gas production processes and is not suitable for environmental protection management of steel enterprises. Other coke oven gas fine desulfurization technologies under medium and low temperature and low pressure conditions are not yet mature and cannot guarantee the high organic sulfur desulfurization efficiency required for ultra-low emission standards.

[0008] Therefore, steel enterprises often need to implement coke oven gas desulfurization and blast furnace gas desulfurization or blast furnace gas / coke oven gas desulfurization at the same time, supplemented by a large amount of blending converter gas, natural gas and other sulfur-free gases as a control measure to meet the standards. Blending a large amount of sulfur-free gas has the disadvantages of large fluctuations in converter gas supply and calorific value, difficulty in control, and high natural gas costs.

[0009] The steel plant gas pipeline network system is complex and has many branches. It is difficult to install a fine desulfurization device on a section of blast furnace gas or coke oven gas main pipe sent to hot rolling. Usually, the fine desulfurization of the entire blast furnace gas and coke oven gas can only be implemented at the gas source, which results in repeated installation of desulfurization facilities, excessive treatment, and high cost and uneconomical realization of environmental protection goals. Figure 1 shown. Utility Model Content

[0010] In order to overcome the defects of the prior art and provide a rolling auxiliary equipment with high desulfurization efficiency and environmental protection, the utility model discloses a mixed coal gas purification device.

[0011] The utility model achieves the invention purpose through the following technical solutions:

[0012] A mixed gas purification device, including a deacidification device, is characterized in that it also includes a first gas mixing device, a compressor, a first cooler, a temperature swing adsorption pretreatment tower, a heater, a hydrolysis tower, a second cooler, a fine desulfurization tower and a second gas mixing device.

[0013] The first coal gas mixing device is connected to the deacidification device, the air inlet of the compressor is connected to the outlet of the first coal gas mixing device, and the air outlet of the compressor is connected to the air inlet of the first cooler;

[0014] The air outlet of the first cooler is connected to the air inlet of the temperature swing adsorption pretreatment tower, the air outlet of the temperature swing adsorption pretreatment tower is connected to the heater, and the temperature swing adsorption pretreatment tower is filled with adsorbent;

[0015] The air inlet of the regeneration gas heater is connected to the air outlet of the fine desulfurization tower, and the air outlet of the regeneration gas heater is connected to the air inlet of the temperature swing adsorption pretreatment tower;

[0016] The air inlet of the heater is connected to the outlet of the temperature swing adsorption pretreatment tower, the air outlet of the heater is connected to the air inlet of the hydrolysis tower, the air outlet of the hydrolysis tower is connected to the air inlet of the second cooler, and the catalyst is filled in the hydrolysis tower;

[0017] The air outlet of the second cooler is connected to the air inlet of the fine desulfurization tower, the air outlet of the fine desulfurization tower is connected to the air inlet of the second mixing device, and the fine desulfurization tower is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer;

[0018] The gas outlet of the second mixing device is connected to the main gas pipe of the steel rolling heating furnace.

[0019] The mixed coal gas purification device is characterized by:

[0020] The deacidification device comprises an alkali washing tower, a spray port and an alkali liquid pump. The bottom and top of the alkali washing tower are respectively provided with an air inlet and an air outlet, the upper part of the alkali washing tower is provided with a spray port, the alkali liquid pump is arranged below the alkali washing tower, the inlet of the alkali liquid pump is connected to the alkali liquid source, and the outlet of the alkali liquid pump is connected to the spray port;

[0021] The adsorbent filled in the temperature swing adsorption pretreatment tower is a combination of activated carbon and coke;

[0022] The hydrolysis tower is filled with a metal-based catalyst including at least one metal element selected from aluminum, titanium and silicon;

[0023] The first gas mixing device includes a blast furnace gas pipe, a blast furnace gas flow meter, a blast furnace gas flow regulating valve, a coke oven gas pipe, a coke oven gas flow meter, a coke oven gas flow regulating valve, a first cut-off valve, a first ratio calculator, a first flow indicating controller and a calorific value controller. The air inlet end of the blast furnace gas pipe is connected to the air outlet of the deacidification device alkali washing tower, and the air outlet end is connected to the air inlet of the compressor. The blast furnace gas pipe is connected in series with the blast furnace gas flow meter and the blast furnace gas flow regulating valve; the air inlet end of the coke oven gas pipe is connected to the air outlet of the coke oven, and the air outlet end is connected to the air outlet end of the blast furnace gas pipe. The air inlet end of the coke oven gas pipe is connected to the air outlet end of the coke oven gas pipe sent to hot rolling, and the air outlet end is connected to the air outlet end of the blast furnace gas pipe sent to hot rolling. The coke oven gas pipe is connected in series with a coke oven gas flow meter, a coke oven gas flow regulating valve and a first shut-off valve in sequence; the first ratio calculator is connected to the blast furnace gas flow meter, the coke oven gas flow meter and the coke oven gas flow regulating valve respectively through signal lines, the calorific value controller is connected to the blast furnace gas flow meter, the coke oven gas flow meter and the coke oven gas flow regulating valve respectively through signal lines, and the first ratio calculator and the calorific value controller are connected to each other through signal lines;

[0024] The second gas mixing device includes a mixed gas pipe, a mixed gas flowmeter, a mixed gas flow regulating valve, a converter gas pipe, a converter gas flowmeter, a converter gas flow regulating valve, a second shut-off valve, a second ratio calculator, a second flow indicating controller and a calorific value meter. The air inlet end of the mixed gas pipe is connected to the air outlet of the fine desulfurization tower, and the air outlet end is connected to the heating furnace. The mixed gas pipe is connected in series with the mixed gas flowmeter and the mixed gas flow regulating valve in sequence; the air inlet end of the converter gas pipe is connected to the air outlet of the converter, and the air outlet end is connected to the gas outlet end of the mixed gas pipe. The converter gas pipe is connected in series with the converter gas flowmeter, the converter gas flow regulating valve and the second shut-off valve; the second ratio calculator is connected to the mixed gas flowmeter, the converter gas flowmeter and the converter gas flow regulating valve through a signal line; the calorific value meter is arranged at the outlet end of the mixed gas pipe; the calorific value controller and the calorific value meter are connected through a signal line.

[0025] When the utility model is used, the following steps are implemented in sequence:

[0026] Deacidification: The acidic component Cl of blast furnace gas from the blast furnace gas network in the deacidification device - Neutralize with alkali solution to reduce Cl - Corrosion to pipelines and equipment and reduction of impact on the efficiency and life of hydrolysis catalysts;

[0027] Blast furnace gas-coke mixing: the deacidified blast furnace gas and coke oven gas are mixed into two mixed gases in a certain proportion in the first gas mixing device. The mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter.

[0028] Pressurization: The mixed coal gas is pressurized in the compressor, so that the pressure of the mixed coal gas can overcome the resistance drop of the subsequent process equipment and pipelines, and meet the gas pressure of the steel rolling heat treatment furnace;

[0029] Cooling: The pressurized mixed gas is cooled to room temperature in the first cooler;

[0030] Temperature swing adsorption: The two mixed coal gases enter the temperature swing adsorption pretreatment tower from the bottom of the tower. The adsorbent in the temperature swing adsorption pretreatment tower selectively adsorbs impurities such as H2S, tar, naphthalene, benzene, etc. in the two mixed coal gases at room temperature. When the impurities adsorbed by the adsorbent in the temperature swing adsorption pretreatment tower reach saturation, it enters the regeneration process;

[0031] Regeneration: During regeneration, a stream of purified gas is taken from the fine desulfurization tower and connected to the temperature swing adsorption pretreatment tower. The purified gas is used as the "regeneration gas" to heat and desorb the impurities in the inner pores of the adsorbent. After the regeneration is complete, the regeneration gas is used to cool the adsorbent bed to bring it down to room temperature. In order to achieve the purpose of continuous production, the temperature swing adsorption pretreatment tower is set with program-controlled valves to switch multiple towers to alternately adsorb and regenerate. The regeneration gas goes to the end users such as boilers equipped with flue gas desulfurization facilities;

[0032] Heating: After removing impurities such as H2S, tar, naphthalene, benzene, etc., the two mixed coal gases are heated to 80℃~150℃ by heat exchange in the heater;

[0033] Hydrolysis: At a temperature of 80℃ to 150℃, the organic sulfur in the two mixed coal gases in the hydrolysis tower, including COS and CS2, reacts with the water vapor contained in the two mixed coal gases under the action of the catalyst to generate H2S.

[0034] Cooling: After hydrolysis, the two mixed coal gases are cooled to room temperature in the second cooler;

[0035] Fine desulfurization: In the fine desulfurization tower, H2S in the two mixed coal gases reacts with the desulfurizer and oxygen to generate elemental sulfur which is stored in the desulfurizer. The desulfurizer is replaced after it is saturated with adsorption.

[0036] High-coke-converter mixing: The purified two-mixed gas and converter gas are mixed in a certain proportion in the second mixing device to form a three-mixed gas, so as to make full use of the converter gas. The mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter to form a calorific value of 1800kcal / standard m 3 ~2400kcal / standard m 3 The three-mixed gas is then sent to the users of steel rolling heat treatment furnace through pipelines.

[0037] During use:

[0038] During deacidification: blast furnace gas is input from the air inlet at the bottom of the deacidification device alkali washing tower, and 5% NaOH solution is sprayed from the spray port at the top of the deacidification device alkali washing tower driven by the alkali liquid pump. The rising blast furnace gas and the sprayed alkali liquid react with each other to remove Cl in the blast furnace gas. - Acidic components make Cl - ≤10mg / Nm 3 The deacidified blast furnace gas enters the first gas mixing device, and the alkali solution absorbs the acidic components of the blast furnace gas and then is pressurized by the alkali solution pump. A part of it is circulated back to the upper spray port of the alkali washing tower, and the other part is output from the deacidification device;

[0039] When blast furnace gas and coke oven gas are mixed: the deacidified blast furnace gas and the coke oven gas from the external coke oven gas network are mixed in the first gas mixing device to form two mixed gases. When the flow rate of the blast furnace gas as the main flow changes, the flow signal of the blast furnace gas is transmitted to the first ratio calculator via the blast furnace gas flow meter, and the flow signal of the coke oven gas is transmitted to the first ratio calculator via the coke oven gas flow meter. The first ratio calculator calculates the flow rate ratio of the blast furnace gas and the coke oven gas according to the preset flow ratio coefficient of the blast furnace gas and the coke oven gas (blast furnace gas: coke oven gas = 29.2%: 45.8 %) calculates the flow value of coke oven gas as the secondary flow, and uses the calculated coke oven gas flow value as the set value of coke oven gas flow control, and controls the coke oven gas flow regulating valve to adjust the flow of coke oven gas through the first ratio calculator, so that the flow ratio of blast furnace gas and coke oven gas remains stable. At this time, the coke oven gas control is a follow-up system, and the coke oven gas flow automatically follows the change of the blast furnace gas flow through the control action, so that the blast furnace gas flow and the coke oven gas flow maintain a certain ratio relationship stably under different working conditions;

[0040] During high-coke-converter mixing, the mixed coal gas after high-coke mixing is mixed with the converter gas from the external converter gas pipeline network in the second gas mixing device to form a three-mixed coal gas. When the flow rates of the two mixed coal gases as the main flow rates change, the flow signals of the two mixed coal gases are transmitted to the second ratio calculator via the mixed gas flow meter, and the flow signal of the converter gas is transmitted to the second ratio calculator via the converter gas flow meter. The second ratio calculator calculates the flow value of the converter gas as the secondary flow rate according to the preset flow ratio coefficient of the two mixed coal gases and the converter gas, and uses the calculated converter gas flow value as the set value of the converter gas flow control. The second ratio calculator controls the converter gas flow rate by The coke oven gas flow regulating valve adjusts the flow of the converter gas so that the flow ratio of the two mixed gases and the converter gas remains stable, thereby keeping the calorific value of the final three mixed gases stable. At this time, the converter gas control is a follow-up system. Through the control action, the converter gas flow automatically follows the change of the mixed gas flow, so that the mixed gas flow and the converter gas flow can stably maintain a certain ratio relationship under different working conditions. The calorific value meter measures the calorific value of the three mixed gases in real time and transmits it to the calorific value controller. When the calorific value of the three mixed gases deviates from the set value, the first ratio calculator adjusts the flow of the coke oven gas by controlling the coke oven gas flow regulating valve to keep the calorific value of the three mixed gases stable.

[0041] The utility model discloses a novel mixed coal gas purification system, the process flow is as follows: Figure 2 As shown, the blast furnace gas and coke oven gas sent to the steel rolling heat treatment furnace are subjected to alkaline washing, deacidification, mixing, pressurization, temperature swing adsorption detarring, naphthalene removal, and heating, and then undergo a hydrolysis conversion reaction. The organic sulfur components in the gas are converted into hydrogen sulfide, and then the hydrogen sulfide is removed by a carbon-based desulfurizer or an iron oxide desulfurizer. The purified gas is then mixed with the converter gas that is basically sulfur-free and sent to the steel rolling heat treatment furnace as fuel. The SO2 concentration in the flue gas emitted after combustion meets the ultra-low emission environmental protection requirements.

[0042] The technical solution of the utility model adopts the technology of mixed coal gas desulfurization before combustion. Compared with the flue gas desulfurization after combustion and the desulfurization of coke oven gas and blast furnace gas at the source before combustion, it has the advantages of small scale of purification equipment, low investment and operation cost, and convenient implementation. It is very suitable for steel mills whose main users of coal gas - blast furnace hot blast stoves, sintering, coking, boilers, self-contained power plants and other processes have already met the ultra-low emission standards and only the steel rolling heat treatment furnace emissions do not meet the standards to achieve ultra-low emission standards for all processes at a relatively low economic cost.

[0043] The utility model organically combines the following five methods: i. wet deacidification, ii. high, coke and converter gas controlled mixing according to calorific value ratio, iii. dry temperature swing adsorption purification, iv. organic sulfur hydrolysis conversion into inorganic sulfur, v. dry removal of hydrogen sulfide, so as to achieve the SO2 concentration of flue gas emission of steel rolling heat treatment furnace meeting the standard.

[0044] The utility model has the following beneficial effects: high desulfurization efficiency, environmental protection, integrated purification, wide applicability, small footprint, and low investment and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Flow chart of the prior art source desulfurization of coke oven gas and blast furnace gas,

[0046] Figure 2 This is a process flow chart of the utility model.

[0047] Figure 3 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0048] The present invention is further described below through specific embodiments. Example 1

[0049] A mixed coal gas purification device, comprising a deacidification device 1, a first coal gas mixing device 2, a compressor 3, a first cooler 4, a temperature swing adsorption pretreatment tower 5, a heater 6, a hydrolysis tower 7, a second cooler 8, a fine desulfurization tower 9 and a second coal gas mixing device 10, such as Figure 3 As shown, the specific structure is:

[0050] The first coal gas mixing device 2 is connected to the deacidification device 1, the air inlet of the compressor 3 is connected to the outlet of the first coal gas mixing device 2, and the air outlet of the compressor 3 is connected to the air inlet of the first cooler 4;

[0051] The air outlet of the first cooler 4 is connected to the air inlet of the temperature swing adsorption pretreatment tower 5, the air outlet of the temperature swing adsorption pretreatment tower 5 is connected to the heater 6, and the temperature swing adsorption pretreatment tower 5 is filled with adsorbent;

[0052] The air inlet of the regeneration gas heater 51 is connected to the air outlet of the fine desulfurization tower 9, and the air outlet of the regeneration gas heater 51 is connected to the air inlet of the temperature swing adsorption pretreatment tower 5;

[0053] The air inlet of the heater 6 is connected to the outlet of the temperature swing adsorption pretreatment tower 5, the air outlet of the heater 6 is connected to the air inlet of the hydrolysis tower 7, the air outlet of the hydrolysis tower 7 is connected to the air inlet of the second cooler 8, and the catalyst is filled in the hydrolysis tower 7;

[0054] The gas outlet of the second cooler 8 is connected to the gas inlet of the fine desulfurization tower 9, and the gas outlet of the fine desulfurization tower 9 is connected to the gas inlet of the second mixing device 10. The fine desulfurization tower 9 is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer;

[0055] The gas outlet of the second mixing device 10 is connected to the main gas pipe of the heating furnace for conveying rolled steel.

[0056] In this embodiment:

[0057] The deacidification device 1 comprises an alkali washing tower 11, a spray port 12 and an alkali liquid pump 13. The bottom and top of the alkali washing tower 11 are respectively provided with an air inlet and an air outlet. The upper part of the alkali washing tower 11 is provided with a spray port 12. The alkali liquid pump 13 is arranged below the alkali washing tower 11. The inlet of the alkali liquid pump 13 is connected to an alkali liquid source, and the outlet of the alkali liquid pump 13 is connected to the spray port 12.

[0058] The adsorbent filled in the temperature swing adsorption pretreatment tower 5 is a combination of activated carbon and coke;

[0059] The hydrolysis tower 7 is filled with a metal-based catalyst including at least one metal element of aluminum, titanium and silicon;

[0060] The first gas mixing device 2 comprises a blast furnace gas pipe 21, a blast furnace gas flow meter 22, a blast furnace gas flow regulating valve 23, a coke oven gas pipe 24, a coke oven gas flow meter 25, a coke oven gas flow regulating valve 26, a first shut-off valve 27, a first ratio calculator 28 and a calorific value controller 29. The air inlet end of the blast furnace gas pipe 21 is connected to the air outlet of the alkali washing tower 11 of the deacidification device 1, and the air outlet end is connected to the air inlet of the compressor 3. The blast furnace gas pipe 21 is connected in series with the blast furnace gas flow meter 22 and the blast furnace gas flow regulating valve 23 in sequence; the air inlet end of the coke oven gas pipe 24 is connected to the coke oven gas sent to the hot rolling mill; The gas outlet end of the pipe is connected to the gas outlet end of the blast furnace gas pipe 21 sent to hot rolling, and the coke oven gas pipe 24 is connected in series with a coke oven gas flowmeter 25, a coke oven gas flow regulating valve 26 and a first shut-off valve 27 in sequence; the first ratio calculator 28 is connected to the blast furnace gas flowmeter 22, the coke oven gas flowmeter 25 and the coke oven gas flow regulating valve 26 through signal lines, and the calorific value controller 29 is connected to the blast furnace gas flowmeter 22, the coke oven gas flowmeter 25 and the coke oven gas flow regulating valve 26 through signal lines, and the first ratio calculator 28 and the calorific value controller 29 are connected to each other through signal lines;

[0061] The second gas mixing device 10 comprises a mixed gas pipe 101, a mixed gas flow meter 102, a mixed gas flow regulating valve 103, a converter gas pipe 104, a converter gas flow meter 105, a converter gas flow regulating valve 106, a second shut-off valve 107, a second ratio calculator 108, and a calorific value meter 109. The gas inlet end of the mixed gas pipe 101 is connected to the gas outlet of the fine desulfurization tower 9, and the gas outlet end is connected to the heating furnace. The mixed gas pipe 101 is connected in series with the mixed gas flow meter 102 and the mixed gas flow regulating valve 103 in sequence; the converter gas pipe 104, the converter gas flow meter 105, the converter gas flow regulating valve 106, the second shut-off valve 107, the second ratio calculator 108, and the calorific value meter 109. The air inlet end of the gas pipe 104 is connected to the air outlet of the converter, and the air outlet end is connected to the air outlet end of the mixed gas pipe 101. The converter gas pipe 104 is connected in series with a converter gas flowmeter 105, a converter gas flow regulating valve 106 and a second shut-off valve 107 in sequence; the second ratio calculator 108 is connected to the mixed gas flowmeter 102, the converter gas flowmeter 105 and the converter gas flow regulating valve 106 through a signal line; the calorific value meter 109 is arranged at the outlet end of the mixed gas pipe 101; the calorific value controller 29 and the calorific value meter 109 are connected through a signal line.

[0062] When this embodiment is used, the following steps are implemented in sequence:

[0063] Deacidification: The acidic component Cl of blast furnace gas from the blast furnace gas network in the deacidification device 1 - Neutralize with alkali solution to reduce Cl - Corrosion to pipelines and equipment and reduction of impact on the efficiency and life of hydrolysis catalysts;

[0064] Specifically, during deacidification, blast furnace gas is input from the air inlet at the bottom of the alkali washing tower 11 of the deacidification device 1, and a 5% NaOH solution is sprayed from the spray port at the top of the alkali washing tower 11 of the deacidification device 1 under the drive of the alkali liquid pump 13. The rising blast furnace gas and the sprayed alkali liquid react with each other to remove Cl in the blast furnace gas. - Acidic components make Cl - ≤10mg / Nm 3 The deacidified blast furnace gas enters the first gas mixing device 2, and the alkali solution absorbs the acidic components of the blast furnace gas and is then pressurized by the alkali solution pump 13. A part of it is circulated back to the upper spray port of the alkali washing tower 11, and the other part is output from the deacidification device 1.

[0065] Blast furnace gas-coke mixing: the deacidified blast furnace gas and coke oven gas are mixed into two mixed gases in a certain proportion in the first gas mixing device 2, and the mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter;

[0066] Specifically, when blast furnace gas and coke oven gas are mixed, the deacidified blast furnace gas and the coke oven gas from the external coke oven gas network are mixed into two mixed gases in the first gas mixing device 2. When the flow rate of the blast furnace gas as the main flow changes, the flow signal of the blast furnace gas is transmitted to the first ratio calculator 28 via the blast furnace gas flow meter 22, and the flow signal of the coke oven gas is transmitted to the first ratio calculator 28 via the coke oven gas flow meter 25. The first ratio calculator 28 calculates the flow rate of the coke oven gas as the secondary flow rate according to the preset flow ratio coefficient of the blast furnace gas and the coke oven gas (blast furnace gas: coke oven gas = 29.2%: 45.8%). The coke oven gas flow rate value calculated is used as the set value of the coke oven gas flow rate control. The first ratio calculator 28 adjusts the flow rate of the coke oven gas by controlling the coke oven gas flow rate regulating valve 26 to keep the flow rate ratio of the blast furnace gas and the coke oven gas stable. At this time, the coke oven gas control is a follow-up system. Through the control action, the coke oven gas flow rate automatically follows the change of the blast furnace gas flow rate, so that the blast furnace gas flow rate and the coke oven gas flow rate can stably maintain a certain ratio relationship under different working conditions. The coke oven gas flowmeter 25, the blast furnace gas flowmeter 22 and the coke oven gas flow rate regulating valve 26 realize the flow indication control function, namely, Flow Indicate Control, referred to as FIC.

[0067] Pressurization: The mixed two coal gases are pressurized in the compressor 3, so that the pressure of the two coal gases can overcome the resistance drop of the subsequent process section equipment and pipelines, and meet the gas pressure of the steel rolling heat treatment furnace.

[0068] Cooling: The pressurized mixed coal gas is cooled to room temperature in the first cooler 4.

[0069] Temperature swing adsorption: The two mixed coal gases enter the temperature swing adsorption pretreatment tower 5 from the bottom of the temperature swing adsorption pretreatment tower 5. The adsorbent in the temperature swing adsorption pretreatment tower 5 selectively adsorbs impurities such as H2S, tar, naphthalene, benzene, etc. in the two mixed coal gases at room temperature. When the impurities adsorbed by the adsorbent in the temperature swing adsorption pretreatment tower 5 reach saturation, it enters the regeneration process.

[0070] Regeneration: During regeneration, a stream of purified gas is taken from the fine desulfurization tower 9 and connected to the temperature swing adsorption pretreatment tower 5. The purified gas is used as the "regeneration gas" to heat and desorb the impurities in the inner pores of the adsorbent. After the regeneration is complete, the regeneration gas is used to cool the adsorbent bed to bring it down to room temperature. In order to achieve the purpose of continuous production, the temperature swing adsorption pretreatment tower 5 is equipped with a programmable valve to switch multiple towers to alternately adsorb and regenerate. The regeneration gas goes to the end users such as the boiler equipped with flue gas desulfurization facilities.

[0071] Heating: After removing impurities such as H2S, tar, naphthalene, benzene, etc., the two mixed coal gases are heated to 80°C~150°C by heat exchange in the heater 6.

[0072] Hydrolysis: At a temperature of 80°C to 150°C, the organic sulfur in the two mixed coal gases in the hydrolysis tower 7, including COS and CS2, undergoes a hydrolysis reaction with the water vapor contained in the two mixed coal gases under the action of a catalyst, and about 50% to 80% of the organic sulfur components are converted into H2S. The reaction equation is as follows:

[0073] COS+H2O=H2S+CO2,

[0074] CS2+2H2O=2H2S+CO2.

[0075] Cooling: After hydrolysis, the two mixed coal gases are cooled to room temperature in the second cooler 8.

[0076] Fine desulfurization: In the fine desulfurization tower 9, H2S in the two mixed coal gases reacts with the desulfurizer and oxygen to generate elemental sulfur which is stored in the desulfurizer. The desulfurizer is replaced after being saturated with adsorption. The reaction equation is as follows:

[0077] 2H2S+O2→2S↓+2H2O,

[0078] 2RS+O2→2S↓+2R+2H2O,

[0079] Fe2O3∙H2O+3H2S=Fe2S3∙H2O+3H2O,

[0080] 2Fe2S3∙H2O+3O2=2Fe2O3∙H2O+6S.

[0081] High-coke-converter mixing: The purified two mixed coal gases and converter gas are mixed in a second mixing device 10 in a certain proportion to form three mixed coal gases, so as to make full use of converter gas. The mixing is controlled by flow meter, flow regulating valve and calorific value meter to form a calorific value of 1800kcal / standard m 3 ~2400kcal / standard m 3 The three-mixed gas is then sent to the users of steel rolling heat treatment furnaces through pipelines;

[0082] Specifically, during high-coke-converter mixing, the mixed coal gas after high-coke mixing is mixed with the converter gas from the external converter gas pipeline network in the second gas mixing device 10 to form a three-mixed coal gas. When the flow rates of the two mixed coal gases as the main flow rate change, the flow signals of the two mixed coal gases are transmitted to the second ratio calculator 108 via the mixed coal gas flow meter 102, and the flow signal of the converter gas is transmitted to the second ratio calculator 108 via the converter gas flow meter 105. The second ratio calculator 108 calculates the flow value of the converter gas as the secondary flow rate according to the preset flow ratio coefficient of the two mixed coal gases and the converter gas, and uses the calculated converter gas flow value as the set value for converter gas flow control. The second ratio calculator 108 adjusts the converter gas flow rate by controlling the converter gas flow regulating valve 106. The flow rate of the three mixed coal gases is controlled so that the flow rate ratio of the two mixed coal gases and the converter gas remains stable, thereby making the calorific value of the final three mixed coal gases stable. At this time, the converter gas control is a follow-up system. Through the control action, the converter gas flow rate automatically follows the change of the mixed coal gas flow rate, so that the mixed coal gas flow rate and the converter gas flow rate can stably maintain a certain ratio relationship under different working conditions. The calorific value meter 109 measures the calorific value of the three mixed coal gases in real time and transmits it to the calorific value controller 29. When the calorific value of the three mixed coal gases deviates from the set value, the first ratio calculator 28 adjusts the flow rate of the coke oven gas by controlling the coke oven gas flow regulating valve 26 to make the calorific value of the three mixed coal gases stable. The calorific value meter 109, the first ratio calculator 28 and the calorific value controller 29 realize the analysis indication control function, namely Analysis Instruction Control, referred to as AIC, which means that the calorific value data measured by the on-site analysis instrument, i.e., the calorific value meter 109 in this embodiment, can be displayed on the spot and participate in the control at the same time.

[0083] Some of the process parameters used in this embodiment are as follows:

[0084] Calorific value of mixed gas required for heating furnace: 1800kcal / standard m 3 ~2400kcal / standard m 3 ,

[0085] Blast furnace gas calorific value: 796kcal / standard m 3 ,

[0086] Coke oven gas calorific value: 4050kcal / standard m 3 ,

[0087] Converter gas calorific value: 1650kcal / standard m 3 ,

[0088] Blast furnace gas flow: coke oven gas flow: 29.2%: 45.8%.

[0089] When the user's gas load suddenly changes, the pressure before gas mixing suddenly changes, or the regulating valves or controllers fail, the pressure at the mixing point may become higher than the coke oven gas pressure, causing the blast furnace gas to flow back into the coke oven gas pipeline, causing the calorific value of the coke oven gas to decrease, thereby affecting other gas consumption points. Therefore, a first shut-off valve 207 and a second shut-off valve 1007 are respectively provided on the coke oven gas pipe 204 and the converter gas pipe 1004 to detect the mixed gas pressure and compare it with the set value, and then output a "high pressure" or "low pressure" signal to determine whether the first shut-off valve 207 and the second shut-off valve 1007 need to be disconnected.

Claims

1. A mixed coal gas purification device, comprising a deacidification device (1), characterized in that: It also includes a first coal gas mixing device (2), a compressor (3), a first cooler (4), a temperature swing adsorption pretreatment tower (5), a heater (6), a hydrolysis tower (7), a second cooler (8), a fine desulfurization tower (9) and a second coal gas mixing device (10). The first coal gas mixing device (2) is connected to the deacidification device (1), the air inlet of the compressor (3) is connected to the outlet of the first coal gas mixing device (2), and the air outlet of the compressor (3) is connected to the air inlet of the first cooler (4); The air outlet of the first cooler (4) is connected to the air inlet of the temperature swing adsorption pretreatment tower (5), the air outlet of the temperature swing adsorption pretreatment tower (5) is connected to the heater (6), and the temperature swing adsorption pretreatment tower (5) is filled with an adsorbent; The air inlet of the regeneration gas heater (51) is connected to the air outlet of the fine desulfurization tower (9), and the air outlet of the regeneration gas heater (51) is connected to the air inlet of the temperature swing adsorption pretreatment tower (5); The air inlet of the heater (6) is connected to the outlet of the temperature swing adsorption pretreatment tower (5), the air outlet of the heater (6) is connected to the air inlet of the hydrolysis tower (7), the air outlet of the hydrolysis tower (7) is connected to the air inlet of the second cooler (8), and the hydrolysis tower (7) is filled with a catalyst; The gas outlet of the second cooler (8) is connected to the gas inlet of the fine desulfurization tower (9), the gas outlet of the fine desulfurization tower (9) is connected to the gas inlet of the second mixing device (10), and the fine desulfurization tower (9) is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer; The gas outlet of the second mixing device (10) is connected to the main gas pipe of the steel rolling heating furnace.

2. The mixed coal gas purification device according to claim 1, characterized in that: The deacidification device (1) comprises an alkali washing tower (11), a spray port (12) and an alkali liquid pump (13); the bottom and top of the alkali washing tower (11) are respectively provided with an air inlet and an air outlet; the upper part of the alkali washing tower (11) is provided with a spray port (12); the alkali liquid pump (13) is arranged below the alkali washing tower (11); the inlet of the alkali liquid pump (13) is connected to an alkali liquid source; and the outlet of the alkali liquid pump (13) is connected to the spray port (12); The first coal gas mixing device (2) comprises a blast furnace gas pipe (21), a blast furnace gas flow meter (22), a blast furnace gas flow regulating valve (23), a coke oven gas pipe (24), a coke oven gas flow meter (25), a coke oven gas flow regulating valve (26), a first shut-off valve (27), a first ratio calculator (28) and a calorific value controller (29); the gas inlet end of the blast furnace gas pipe (21) is connected to the gas outlet of the alkali washing tower (11) of the deacidification device (1), and the gas outlet end is connected to the gas inlet of the pressurizing machine (3); the blast furnace gas flow meter (22) and the blast furnace gas flow regulating valve (23) are connected in series in sequence on the blast furnace gas pipe (21); the gas inlet end of the coke oven gas pipe (24) is connected to the coke oven gas pipe (25) and the coke oven gas pipe (26) is connected to the coke oven gas pipe (26) and the coke oven gas pipe (26) is connected to the coke oven gas pipe (26) and the coke oven gas pipe (26) is connected to the coke oven gas pipe (26) and the coke oven gas pipe (26) is connected to the coke oven gas pipe (26) and the coke oven gas pipe (26) is connected to the coke oven gas pipe (26) and the coke oven gas pipe (26) The gas outlet end of the blast furnace gas pipe is connected to the gas outlet end of the blast furnace gas pipe (21) for hot rolling, and the coke oven gas pipe (24) is connected in series with a coke oven gas flow meter (25), a coke oven gas flow regulating valve (26) and a first shut-off valve (27); the first ratio calculator (28) is connected to the blast furnace gas flow meter (22), the coke oven gas flow meter (25) and the coke oven gas flow regulating valve (26) through signal lines, the calorific value controller (29) is connected to the blast furnace gas flow meter (22), the coke oven gas flow meter (25) and the coke oven gas flow regulating valve (26) through signal lines, and the first ratio calculator (28) and the calorific value controller (29) are connected to each other through signal lines; The second coal gas mixing device (10) comprises a mixed coal gas pipe (101), a mixed coal gas flow meter (102), a mixed coal gas flow regulating valve (103), a converter coal gas pipe (104), a converter coal gas flow meter (105), a converter coal gas flow regulating valve (106), a second shut-off valve (107), a second ratio calculator (108) and a calorific value meter (109); the gas inlet end of the mixed coal gas pipe (101) is connected to the gas outlet of the fine desulfurization tower (9), and the gas outlet end is connected to the heating furnace; the mixed coal gas flow meter (102) and the mixed coal gas flow regulating valve (103) are sequentially connected in series on the mixed coal gas pipe (101); The gas inlet end of the gas pipe (104) is connected to the gas outlet of the converter, and the gas outlet end is connected to the gas outlet end of the mixed gas pipe (101). The converter gas pipe (104) is connected in series with a converter gas flow meter (105), a converter gas flow regulating valve (106) and a second shut-off valve (107). The second ratio calculator (108) is connected to the mixed gas flow meter (102), the converter gas flow meter (105) and the converter gas flow regulating valve (106) via a signal line. The calorific value meter (109) is arranged at the outlet end of the mixed gas pipe (101). The calorific value controller (29) and the calorific value meter (109) are connected via a signal line.

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