Fixed bed reaction evaluation device and method for catalytic reduction of carbon dioxide by coke and / or petroleum coke

Abstract

The present invention relates to the technical field of carbon dioxide reduction, and discloses a fixed-bed reaction evaluation device and a method for catalytic reduction of carbon dioxide by coke and / or petroleum coke. The device includes: an intake unit, a reaction unit, a product treatment unit, a tail gas treatment unit, and a system control unit connected in sequence; wherein, the reaction unit includes a reactor, and the reactor includes a horizontal heating furnace and a reaction tube horizontally arranged in the horizontal heating furnace. The reaction tube includes an outer corundum tube and an inner corundum tube. A graphite sealing ring is arranged between the outer corundum tube and the inner corundum tube, and a gas distribution plate with through holes is arranged at the inlet end of the inner corundum tube. The fixed-bed reaction evaluation device provided by the present invention, with the reaction tube placed horizontally and the double-tube setting of the outer corundum tube and the inner corundum tube, can solve the problem of catalyst bed plugging and has a high safety factor.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide reduction, and in particular to a fixed bed reaction evaluation device and a method for catalytic reduction of carbon dioxide by coke and / or petroleum coke. Background Art

[0002] Since the Industrial Revolution, the fossil energy consumed by humans has increased day by day, resulting in an increasing content of greenhouse gases in the atmosphere. High levels of greenhouse gases have already brought about significant global warming effects. Among the many greenhouse gases, carbon dioxide has the greatest impact on global warming, accounting for about 55% of the total global warming effect. How to achieve the conversion and utilization of carbon dioxide is an important means of reducing carbon dioxide emissions, which has attracted widespread attention from countries around the world.

[0003] Reducing carbon dioxide to carbon monoxide is one of the main ways to utilize carbon dioxide chemically. At present, laboratories generally use fixed bed reactors to study carbon dioxide reduction reactions. Studies have found that coke and / or petroleum coke have the advantage of high catalytic activity when used for catalytic reduction of carbon dioxide. However, the reaction temperature of coke and / or petroleum coke for catalytic reduction of carbon dioxide is above 1000°C. Under high temperature conditions, the colloidal substances contained in coke and / or petroleum coke are easily liquefied and precipitated, which prevents the normal use of conventional fixed bed reactors. It is easy to cause catalyst bed blockage, causing the reactor pressure to surge, and thus causing safety accidents. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that when coke and / or petroleum coke are used for catalytic reduction of carbon dioxide, the reactor cannot be operated normally, and a fixed bed reaction evaluation device and a method for catalytic reduction of carbon dioxide by coke and / or petroleum coke are provided. The device is used to use coke and / or petroleum coke as a catalyst bed in a fixed bed reactor, and the reactor can operate normally for a long time without the risk of blockage.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a fixed bed reaction evaluation device, which includes: an air intake unit, a reaction unit, a product treatment unit, an exhaust gas treatment unit and a system control unit connected in sequence; wherein, the reaction unit includes a reactor, the reactor includes a horizontal heating furnace and a reaction tube horizontally arranged in the horizontal heating furnace, the reaction tube includes an outer corundum tube and an inner corundum tube, a graphite sealing ring is arranged between the outer corundum tube and the inner corundum tube, and a gas distribution plate with through holes is arranged at the inlet end of the inner corundum tube.

[0006] The second aspect of the present invention provides a method for catalytic reduction of carbon dioxide with coke and / or petroleum coke. The method includes contacting a raw material gas with the coke and / or petroleum coke to carry out a reduction reaction to obtain carbon monoxide. Among them, the method is carried out in the evaluation device described in the first aspect of the present invention, and the raw material gas includes carbon dioxide and optionally oxygen.

[0007] Through the above technical solutions, the technical effects achieved by the technical solutions provided by the present invention are as follows:

[0008] 1) The fixed-bed reaction evaluation device provided by the present invention has a reaction tube placed horizontally and a double-tube setting of an outer corundum tube and an inner corundum tube, so that the coke and / or petroleum coke is placed in the inner corundum tube to form a catalyst bed layer, realizing the horizontal transverse passage of the reaction inlet gas containing carbon dioxide through the catalyst bed layer. When the coke and / or petroleum coke undergoes a carbon dioxide reduction reaction at a high temperature (above 1000 °C), even if the colloidal substances contained in the coke and / or petroleum coke are liquefied and precipitated, there is only a change in the vertical direction of the catalyst bed layer, without affecting the blockage of the reaction inlet gas from passing horizontally through the catalyst bed layer. The problem of catalyst bed layer blockage can be solved, and the safety factor of the catalytic reduction of carbon dioxide fixed-bed reaction evaluation device constructed with the coke and / or petroleum coke as the catalyst bed layer is high.

[0009] 2) The fixed-bed reaction evaluation device provided by the present invention uses a catalyst loading mesh to shape the catalyst placed in the horizontally placed inner corundum tube. The loading is convenient, and it can ensure that the loaded catalyst remains cylindrical in the inner corundum tube, making the contact between the raw material gas and the catalyst more uniform.

[0010] 3) The fixed-bed reaction evaluation device provided by the present invention has a tail gas treatment unit including a reaction furnace for catalytic combustion of the gas phase separated from the gas-liquid separator, which can prevent carbon monoxide from polluting the environment.

[0011] 4) The method for catalytic reduction of carbon dioxide with coke and / or petroleum coke provided by the present invention enables the coke and / or petroleum coke to achieve carbon dioxide reduction at a high temperature of up to 1100 - 1450 °C and can operate stably, and the content of carbon monoxide in the reaction product is above 45 v%. Description of the Drawings

[0012] Figure 1 is a schematic structural diagram of a reactor in a preferred embodiment provided by the present invention.

[0013] Description of the Reference Numerals in the Drawings

[0014] 1, reaction tube; 11, outer corundum tube; 12, inner corundum tube

[0015] 13, graphite sealing ring; 14, gas distribution plate; 15, catalyst loading mesh

[0016] 16, Thermocouple 161, Corundum thermocouple wire segment 162, Stainless steel thermocouple wire segment Detailed implementation mode

[0017] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0018] The first aspect of the present invention provides a fixed-bed reaction evaluation device, which includes: an air inlet unit, a reaction unit, a product treatment unit, a tail gas treatment unit, and a system control unit connected in sequence; wherein, the reaction unit includes a reactor, and the reactor includes a horizontal heating furnace and a reaction tube 1 horizontally arranged in the horizontal heating furnace. The reaction tube includes an outer corundum tube 11 and an inner corundum tube 12. A graphite sealing ring 13 is arranged between the outer corundum tube and the inner corundum tube. The inlet end of the inner corundum tube is provided with a gas distribution plate 14 with through holes, specifically as Figure 1 shown.

[0019] In the air inlet unit:

[0020] In a preferred implementation mode, the air inlet unit includes a purge gas inlet, a carbon dioxide inlet, a mixer, a preheater, and an optional oxygen inlet; wherein, the purge gas inlet, the carbon dioxide inlet, and the optional oxygen inlet are all connected to the mixer, the mixer is connected to the preheater, and the preheater is connected to the reaction unit.

[0021] In a preferred implementation mode, the air inlet unit further includes at least two filters and at least two flow meters; wherein, along the gas flow direction, on the pipeline connecting the carbon dioxide inlet and the mixer, a filter and a flow meter are arranged in sequence, and on the pipeline connecting the oxygen inlet and the mixer, a filter and a flow meter are arranged in sequence.

[0022] In the present invention, the filter is used to remove solid particles below 7μm. The filtered carbon dioxide gas is adjusted in flow rate by the flow meter and then enters the preheater through the mixer for preheating to obtain preheated gas; or the filtered carbon dioxide and oxygen are respectively adjusted in mass ratio by the flow meter and then first mixed in the mixer and then enter the preheater for preheating to obtain preheated gas. The obtained preheated gas then enters the reactor to contact the catalyst and react.

[0023] In a preferred implementation mode, the preheater is connected to the outer corundum tube 21 in the reaction unit.

[0024] In the reaction unit:

[0025] In a preferred embodiment, the horizontal heating furnace has a double-layer shell structure, the furnace tubes are made of high-purity special materials, and the furnace chamber is made of polycrystalline alumina fiber.

[0026] Among them, the setting of the double-layer shell structure and the selection of the materials for the furnace tubes and the furnace chamber can improve the high-temperature resistance of the fixed-bed reaction evaluation device. The high-purity special material tube refers to a porcelain corundum tube with a purity of 99%.

[0027] In a preferred embodiment, the porosity of the gas distribution plate 14 is 70-95%, preferably 80-85%.

[0028] Among them, the inventors of the present invention have found through research that by arranging a gas distribution plate at the inlet end of the inner corundum tube, the raw material gas can be more evenly distributed in the inner corundum tube, which helps to improve the mixing uniformity of the raw material gas and the catalyst and improve the catalytic effect.

[0029] In a preferred embodiment, the diameter of the through holes on the gas distribution plate 14 is 1-10 mm, preferably 3-6 mm.

[0030] In a preferred embodiment, the reactor further includes a catalyst loading mesh 15, and the catalyst loading mesh 15 is arranged inside the inner corundum tube 12 for fixing the catalyst.

[0031] Among them, in the present invention, the coke and / or petroleum coke used as the catalyst is first loaded into the catalyst loading mesh, and then the catalyst loading mesh is placed inside the inner corundum tube, and the catalyst placed in the horizontally placed inner corundum tube is shaped, filling the inner corundum tube to form a catalyst bed layer, and ensuring that the loaded catalyst remains cylindrical in the inner corundum tube, so that the raw material gas contacts the catalyst more evenly. The formed catalyst bed layer is adjacent to the gas distribution plate 14. The raw material gas first passes through the gas distribution plate 14 and then immediately passes through the catalyst bed layer.

[0032] In a preferred embodiment, the reaction unit further includes a thermocouple 16 arranged inside the inner corundum tube. The thermocouple wire of the thermocouple includes a corundum thermocouple wire segment 161 and a stainless steel thermocouple wire segment 162. Among them, the corundum thermocouple wire segment 161 is close to the inlet end of the inner corundum tube, and the stainless steel thermocouple wire segment 162 is close to the outlet end of the inner corundum tube.

[0033] In the present invention, the thermocouple wire in series with corundum and stainless steel can improve the heat resistance of the thermocouple and the temperature control performance of the fixed-bed reaction evaluation device.

[0034] In a preferred embodiment, the reaction unit further includes a safety valve, which is connected to the inner corundum tube. When the pressure in the inner corundum tube exceeds the pressure set by the safety valve, the safety valve will automatically open for venting to relieve pressure, and the vented gas directly enters the tail gas treatment unit.

[0035] In a preferred embodiment, graphite sealing rings 13 are respectively arranged between the outer corundum tube and the inner corundum tube, at the inlet end and the outlet end of the inner corundum tube.

[0036] In the product treatment unit:

[0037] In a preferred embodiment, the product treatment unit includes an air cooler, a water cooler, a gas-liquid separator, and a liquid-phase storage tank connected in sequence; among them, the air cooler is connected to the reactor.

[0038] The gas coming out of the inner corundum tube enters the gas-liquid separator after being cooled by the air cooler and the water cooler in two stages. The liquid phase separated from the gas-liquid separator enters the liquid-phase storage tank for storage, and the gas phase separated from the gas-liquid separator enters the tail gas treatment unit.

[0039] In the tail gas treatment unit:

[0040] In a preferred embodiment, the tail gas treatment unit includes a tail gas sampling port and a reaction furnace, and the tail gas sampling port and the reaction furnace are respectively connected to the gas-liquid separator; among them, the tail gas sampling port is used for sampling and analysis. For example, the gas phase separated from the gas-liquid separator can be introduced into a concentration analysis device for product analysis; the reaction furnace is used for catalytic combustion of the gas phase separated from the gas-liquid separator to prevent carbon monoxide from polluting the environment.

[0041] In the present invention, when the gas phase separated from the gas-liquid separator is introduced into the concentration analysis device for product analysis, the gas discharged from the concentration analysis device can also be introduced into the reaction furnace for combustion treatment.

[0042] In a preferred embodiment, to prevent carbon monoxide in the tail gas from reaching the explosion limit and causing an explosion, preferably, an air inlet is provided on the pipeline connecting the gas-liquid separator and the reaction furnace. By mixing the gas phase separated from the gas-liquid separator with air and then introducing it into the reaction furnace, the concentration of carbon monoxide can be diluted to avoid safety accidents.

[0043] In the control system:

[0044] In a preferred embodiment, the present invention does not make special limitations on the control system, and it can be selected according to the conventional operations in the art, and the present invention will not elaborate one by one.

[0045] The second aspect of the present invention provides a method for catalytic reduction of carbon dioxide with coke and / or petroleum coke. The method includes contacting a raw material gas with coke and / or petroleum coke to carry out a reduction reaction to obtain carbon monoxide. Among them, the method is carried out in the evaluation device described in the first aspect of the present invention, and the raw material gas includes carbon dioxide and optionally oxygen.

[0046] In a preferred embodiment, before contacting the raw material gas with coke and / or petroleum coke, it is preferred to preheat the raw material gas. The preheating temperature is 350 - 650 °C, preferably 500 - 550 °C.

[0047] In a preferred embodiment, the reaction temperature of the reduction reaction is 1100 - 1450 °C, preferably 1200 - 1350 °C.

[0048] In a preferred embodiment, the reduction reaction is carried out at normal pressure. Among them, the present invention does not make special limitations on normal pressure, and it can be understood according to the conventional understanding.

[0049] In a preferred embodiment, the volumetric space velocity of the carbon dioxide is 15 - 75 min -1 , preferably 62.5 - 75 min -1 .

[0050] In a preferred embodiment, the volumetric space velocity of the oxygen is 15 - 37.5 min -1 , preferably 20 - 27.5 min -1 .

[0051] In a preferred embodiment, the method is carried out in the evaluation device described in the first aspect of the present invention and includes the following steps: 1) Charge coke and / or petroleum coke in the catalyst loading mesh, and then compact it on the gas distribution plate of the inner corundum tube, so that the catalyst loading mesh filled with coke and / or petroleum coke remains cylindrical in the inner corundum tube; 2) Use a graphite sealing ring to seal and connect the inner corundum tube horizontally placed in the outer corundum tube to the outer corundum tube, then insert a thermocouple into the inner corundum tube, and seal and connect the reaction tube to the evaluation device; 3) First, open the connected purge gas pipeline for purging, then switch the connected carbon dioxide gas pipeline. The carbon dioxide with the flow rate adjusted by the flow meter enters the reactor after being preheated in the preheater and reacts with the coke and / or petroleum coke in the reactor. The reaction products leave the reactor and then enter the air cooler, water cooler, and gas-liquid separator in sequence; or first, open the connected purge gas pipeline for purging, then switch the connected carbon dioxide gas pipeline and oxygen gas pipeline. The carbon dioxide and oxygen with the flow rates adjusted by the flow meters are first mixed in the mixer, then preheated in the preheater, and then enter the reactor, where they react with the coke and / or petroleum coke. The reaction products leave the reactor and then enter the air cooler, water cooler, and gas-liquid separator in sequence; 4) The liquid-phase product separated from the gas-liquid separator is stored in the liquid-phase storage tank. For the gas-phase product separated from the gas-liquid separator, part of it is introduced into the concentration analysis device through the tail gas sampling port for product analysis, and part of it can be introduced into the reaction furnace for combustion or stored.

[0052] The present invention will be described in detail below through examples.

[0053] The fixed-bed reaction evaluation device used in the examples includes an intake unit, a reaction unit, a product treatment unit, a tail gas treatment unit, and a system control unit connected in sequence;

[0054] Among them, the intake unit includes a purge gas inlet, a carbon dioxide inlet, and an oxygen inlet. The purge gas inlet, carbon dioxide inlet, and oxygen inlet are all connected to the mixer. On the pipeline connecting the carbon dioxide inlet to the mixer, a filter and a flow meter are arranged in sequence. On the pipeline connecting the oxygen inlet to the mixer, a filter and a flow meter are arranged in sequence. The mixer is connected to the preheater, and the preheater is connected to the reactor in the reaction unit; the purge gas inlet is connected to a nitrogen gas cylinder, the carbon dioxide inlet is connected to a carbon dioxide cylinder, and the oxygen inlet is connected to an oxygen cylinder;

[0055] The reaction unit is as Figure 1Shown as follows: including a reactor, a thermocouple and a safety valve. Among them, the reactor includes a horizontal heating furnace and a reaction tube horizontally arranged in the horizontal heating furnace. The furnace tube of the horizontal heating furnace is a double-layer shell structure, the furnace tube is a high-purity special material tube, and the furnace chamber is a polycrystalline alumina fiber; the reaction tube includes an outer corundum tube, an inner corundum tube and a catalyst loading net, a graphite sealing ring for sealing and connecting the outer corundum tube and the inner corundum tube, a gas distribution plate is arranged at the inlet end of the inner corundum tube, through holes with a diameter of 3 mm are uniformly arranged on the gas distribution plate, and the porosity of the gas distribution plate is 85%; a thermocouple is arranged in the inner corundum tube, the front end of the thermocouple wire is a corundum thermocouple wire, and the rear end is a stainless steel thermocouple wire; the inner corundum tube is also respectively connected to the safety valve and the air cooler in the product treatment unit;

[0056] The product treatment unit includes an air cooler, a water cooler, a gas-liquid separator and a liquid-phase storage tank connected in sequence; the tail gas treatment unit includes a tail gas sampling port and a reaction furnace, the tail gas sampling port and the reaction furnace are respectively connected to the gas-liquid separator, and an air inlet is arranged on the pipeline connecting the reaction furnace and the gas-liquid separator.

[0057] Example 1

[0058] First, 200 g of petroleum coke is loaded into the catalyst loading net, put into the inner corundum tube, and compacted on the gas distribution plate of the inner corundum tube to keep it cylindrical; then the horizontally placed inner corundum tube is sealed and connected to the outer corundum tube by using a graphite sealing ring, and then the thermocouple is inserted into the inner corundum tube, and the reaction tube is sealed and connected to the evaluation device;

[0059] Under normal pressure, first use nitrogen to purge the fixed-bed reaction evaluation device for 15 min to evacuate the air, and then start heating. When the reactor is heated to 1200 °C, carbon dioxide preheated to 500 °C and with a flow rate of 1.5 L / min is introduced and the timing starts;

[0060] Part of the gas phase separated from the gas-liquid separator is mixed with air and sent to the reaction furnace for combustion, and part is introduced into the concentration analysis device through the tail gas sampling port for tail gas analysis, and the tail gas discharged from the concentration analysis device is sent to the reaction furnace for combustion.

[0061] Among them, the performance of catalytic reduction of carbon dioxide by petroleum coke is studied by using the fixed-bed reaction evaluation device of the present invention. The inlet and outlet gas flow rates are stable, the pressure basically remains unchanged, there will be no problem of blocking the catalyst bed layer, and the device can operate stably for a long time. After the device has been operating stably for 10 h, through analysis, it can be known that the CO2 content in the tail gas is 45.1 v%, the CO content is 49.3 v%, and the O2 content is 0.

[0062] Example 2

[0063] Same as Example 1, the difference is that: the reactor is heated to 1250 °C.

[0064] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 20.5 v%, the CO content is 69.8 v%, and the O2 content is 0.

[0065] Example 3

[0066] Same as Example 1, the difference is that the reactor is heated to 1300 °C.

[0067] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 16.0 v%, the CO content is 74.7 v%, and the O2 content is 0.

[0068] Example 4

[0069] Same as Example 1, the difference is that the reactor is heated to 1350 °C.

[0070] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 13.2 v%, the CO content is 76.8 v%, and the O2 content is 0.

[0071] Example 5

[0072] Same as Example 1, the difference is that the raw material gas is carbon dioxide and oxygen. Among them, the flow rate of carbon dioxide is 1.5 L / min, and the flow rate of oxygen is 0.5 L / min.

[0073] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 39.2%, the CO content is 53.4 v%, and the O2 content is 0.8 v%.

[0074] Example 6

[0075] Same as Example 5, the difference is that the reactor is heated to 1250 °C.

[0076] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 18.3 v%, the CO content is 74.6 v%, and the O2 content is 0.6 v%.

[0077] Example 7

[0078] Same as Example 5, the difference is that the reactor is heated to 1300 °C.

[0079] The device can operate stably for 12 h. Among them, after operating stably for 10 h, in the gas phase separated from the gas-liquid separator, the CO2 content is 15.7 v%, the CO content is 77.9 v%, and the O2 content is 0.2 v%.

[0080] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for catalytic reduction of carbon dioxide with coke and / or petroleum coke, characterized in that, The method includes contacting a raw material gas with coke and / or petroleum coke to carry out a reduction reaction to obtain carbon monoxide; wherein, the method is carried out in a fixed-bed reaction evaluation device, and the raw material gas includes carbon dioxide. The fixed-bed reaction evaluation device includes: an intake unit, a reaction unit, a product treatment unit, a tail gas treatment unit, and a system control unit connected in sequence. Among them, the reaction unit includes a reactor, and the reactor includes a horizontal heating furnace and a reaction tube horizontally arranged in the horizontal heating furnace. The reaction tube includes an outer corundum tube and an inner corundum tube. A graphite sealing ring is arranged between the outer corundum tube and the inner corundum tube. The inlet end of the inner corundum tube is provided with a gas distribution plate having through holes. Among them, the reactor further includes a catalyst loading mesh, and the catalyst loading mesh is arranged inside the inner corundum tube to fix the catalyst to form a catalyst bed layer, and the formed catalyst bed layer is adjacent to the gas distribution plate.

2. The method according to claim 1, wherein, The raw material gas further includes oxygen.

3. The method according to claim 2, wherein, The intake unit includes a purge gas inlet, a carbon dioxide inlet, a mixer, a preheater, and an oxygen inlet; wherein, the purge gas inlet, the carbon dioxide inlet, and the oxygen inlet are all connected to the mixer, the mixer is connected to the preheater, and the preheater is connected to the reaction unit.

4. The method according to claim 1, wherein The horizontal heating furnace has a double-layer shell structure, the furnace tube is a high-purity special material tube, and the furnace chamber is a polycrystalline alumina fiber.

5. The method according to claim 1, wherein The porosity of the gas distribution plate is 70-95%.

6. The method according to claim 5, wherein, The porosity of the gas distribution plate is 80-85%.

7. The method according to claim 5, wherein The diameter of the through holes on the gas distribution plate is 1-10 mm.

8. The method according to claim 5, wherein The diameter of the through holes on the gas distribution plate is 3-6 mm.

9. The method according to claim 1, wherein, The reaction unit further includes a thermocouple arranged inside the inner corundum tube. The thermocouple wire of the thermocouple includes a corundum thermocouple wire section and a stainless steel thermocouple wire section; wherein, the corundum thermocouple wire section is close to the inlet end of the inner corundum tube, and the stainless steel thermocouple wire section is close to the outlet end of the inner corundum tube.

10. The method according to claim 1, wherein, The product treatment unit includes an air cooler, a water cooler, a gas-liquid separator, and a liquid-phase storage tank connected in sequence; wherein, the air cooler is connected to the reactor.

11. The method according to claim 1, wherein The tail gas treatment unit includes a tail gas sampling port and a reaction furnace, and the tail gas sampling port and the reaction furnace are respectively connected to the gas-liquid separator.

12. The method according to claim 11, wherein, An air inlet is provided on the pipeline connecting the gas-liquid separator and the reaction furnace for diluting the tail gas.

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