Carbon molecular sieve carbon deposition reaction gas conditioning process

Abstract

This invention discloses a carbon molecular sieve carbon deposition reaction gas conditioning process, comprising the following steps: S1, spreading CMS flat in the furnace chamber (1) of a fixed-bed heating furnace to form a horizontal bed (2) with a thickness ≤50cm; S2, introducing carrier gas into the furnace chamber (1) and venting the air in the furnace chamber (1); S3, heating the furnace chamber (1) to 800±50℃; S4, mixing the carbon source gas and carrier gas to obtain a reaction gas, introducing the reaction gas into the furnace chamber (1), forming a reaction gas flow in the furnace chamber (1), alternating the flow direction of the reaction gas flow, passing vertically through the bed (2) until the reaction is completed; S5, the carrier gas passes through the furnace chamber (1) at a large flow rate, reducing the temperature of the furnace chamber (1) to below 300℃ within 10min, and obtaining the finished product. This invention has the advantages of uniform deposition, low dispersion of CMS in the same batch, no CMS breakage, and convenient operation, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of carbon molecular sieves, and particularly relates to a process for regulating the gas in a carbon molecular sieve carbon deposition reaction. Background Technology

[0002] The core of carbon molecular sieve (CMS) deposition reaction gas regulation is to precisely control the type, concentration, flow rate, ratio of carbon source gas and carrier gas, and to "finely refine" the micropores of CMS at high temperature, so as to reduce the pore size to the range of 0.3–0.4 nm, thereby achieving O2 / N2 kinetic separation (nitrogen production) or other gas separation.

[0003] In existing processes, methane is commonly used as the carbon source gas. Methane is decomposed into carbon atoms and hydrogen at high temperatures, and carbon atoms preferentially deposit at the pore openings of the micropores. Nitrogen or argon is used as the carrier gas. The carrier gas can dilute the carbon source gas, control the deposition rate, avoid clogging of CMS micropores, and narrow the pore size distribution range. The carrier gas also plays a role in venting oxygen in the reactor.

[0004] Under current processes, CMS is reacted at around 800℃. There are two types of reactors. The first is a rotary furnace, where the CMS is continuously tumbled inside, agitated during the reaction, and deposited uniformly with carbon atoms. This results in lower dispersion within the same batch of CMS and better performance. However, some CMS have lower structural strength and are prone to breakage during tumbling, producing debris that requires subsequent reprocessing, which is quite troublesome. The second type is a fixed-bed furnace, where a porous sieve plate is installed inside the furnace, and CMS is evenly spread on it to a thickness of 30-50cm to form a bed. The carbon source gas and carrier gas are mixed to form the reaction gas, which passes through the top or bottom of the furnace. The gas flow passes through the bed from bottom to top or top to bottom. Because the CMS remains stationary during the reaction, it does not break or produce debris. However, the CMS near the inlet side deposits faster than the CMS near the outlet side. As the bed thickness increases, the velocity difference widens, leading to higher dispersion within the same batch of CMS. Summary of the Invention

[0005] The purpose of this invention is to provide a gas conditioning process for carbon molecular sieve carbon deposition reaction. This invention offers advantages such as uniform deposition, low batch dispersion of CMS, no CMS breakage, and ease of operation, making it suitable for large-scale industrial production.

[0006] The technical solution of this invention: a gas conditioning process for carbon molecular sieve carbon deposition reaction, comprising the following steps,

[0007] S1. Spread CMS flat inside the furnace chamber of the fixed-bed heating furnace to form a horizontal bed with a bed thickness ≤50cm;

[0008] S2. Introduce carrier gas into the furnace to purge the air from the furnace.

[0009] S3. The furnace temperature is raised to 800±50℃;

[0010] S4. Mix the carbon source gas and the carrier gas to obtain the reaction gas. Introduce the reaction gas into the furnace to form a reaction gas flow. The reaction gas flow alternates and changes direction, passing vertically through the bed until the reaction is completed.

[0011] S5. A large flow of carrier gas passes through the furnace, reducing the furnace temperature to below 300°C within 10 minutes, thus obtaining the finished product.

[0012] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, in step S4, the time interval between alternating flow directions of the reaction gas flow is 5-10 minutes, and the number of times the reaction gas flow passes through the bed from top to bottom is the same as the number of times it passes through the bed from bottom to top.

[0013] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, the furnace is provided with multiple bed layers arranged from top to bottom, each of which is equipped with an air inlet pipe. The top and bottom of the furnace are equipped with exhaust valves, and the outlet of the exhaust valves and the air inlet end of the air inlet pipes are located outside the heating furnace.

[0014] In the carbon molecular sieve carbon deposition reaction gas conditioning process described above, the air inlet pipe is repeatedly bent in the horizontal direction, and multiple air holes are provided at the top and bottom of the air inlet pipe.

[0015] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, the outer side of the furnace is equipped with a controller, a first gas source, a second gas source, and a gas mixer. The first gas source provides carrier gas, and the second gas source provides carbon source gas. The first and second gas sources are respectively connected to the two inlets of the gas mixer through a first valve and a second valve. The outlet of the gas mixer is connected to two fourth valves through a reversing valve. The two fourth valves are respectively connected to the air inlet pipe located at the bottom of the furnace and the air inlet pipe located at the top of the furnace. The remaining air inlet pipes are connected to the second gas source through a fifth valve. The first gas source is connected to the air inlet pipe at the bottom through a third valve. The first, second, fifth, and third valves are all connected to the signal output terminal of the controller.

[0016] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, each of the overhead layers is equipped with a temperature compensation mechanism connected to the controller, so that the temperature difference of each overhead layer is less than 5°C.

[0017] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, the temperature compensation mechanism includes a temperature sensor and a linear heating element. The temperature sensor is connected to the signal input terminal of the controller, and the heating element is connected to the signal output terminal of the temperature sensor.

[0018] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, the heating element is fixed to the air inlet pipe, which is made of aluminum or copper.

[0019] In the aforementioned carbon molecular sieve carbon deposition reaction gas conditioning process, a concentration sensor is installed in each overhead layer to detect the concentration of carbon source gas, and the concentration sensor is connected to a controller.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] First, it solves the problem of uneven deposition caused by unidirectional airflow in fixed-bed heating furnaces. By alternating airflow, the deposition rate of CMS on the upper and lower sides of the bed tends to be consistent. Experimental verification shows that the dispersion of CMS in the same batch is reduced by more than 30%.

[0022] Secondly, the fixed-bed design keeps the CMS stationary, avoiding the breakage problem caused by CMS tumbling in the rotary kiln. This reduces debris generation to zero, eliminating the need for subsequent secondary processing and improving production efficiency.

[0023] Third, the deposition reaction between carbon source gas and CMS is an endothermic reaction. The reaction gas passing through each bed layer will cause temperature differences and carbon source gas concentration differences in the furnace height direction. This invention sets up a temperature compensation mechanism and a concentration sensor to ensure that the temperature difference between each overhead layer is less than 5°C and the carbon source gas concentration difference is kept within 5%, thereby further ensuring deposition uniformity and further reducing the dispersion of CMS.

[0024] Fourth, the air intake pipe uses aluminum or copper pipe, which has excellent thermal conductivity. Combined with linear heating elements, it can quickly achieve temperature compensation and ensure that the temperature difference between each air-conditioned floor is small.

[0025] Fifth, the entire process is automated through a controller, making it easy to operate, reducing manual intervention, and improving production stability.

[0026] Sixth, at the end of the process, a large flow of carrier gas is introduced to rapidly cool the furnace, reducing the time that the deposition reaction continues uncontrolled at residual temperature, thus reducing the dispersion of CMS.

[0027] Therefore, the present invention has the advantages of uniform deposition, low dispersion of CMS in the same batch, no CMS breakage, and convenient operation, making it suitable for large-scale industrial production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the internal structure of the furnace.

[0029] Figure 2 This is a schematic diagram of the gas path of the present invention.

[0030] Figure 3 This is the electrical control schematic diagram of the present invention.

[0031] The labels in the attached diagram are as follows: 1-furnace, 2-bed, 3-above-ground layer, 4-exhaust valve, 5-inlet pipe, 6-fifth valve, 7-reversing valve, 8-fourth valve, 9-gas vent, 10-controller, 11-first gas source, 12-second gas source, 13-first valve, 14-second valve, 15-gas mixer, 16-third valve, 17-temperature sensor, 18-heating element, 19-concentration sensor. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0033] Example: A process for regulating the reactive gas of carbon molecular sieve carbon deposition, such as... Figure 1 As shown, it includes the following steps:

[0034] S1. The furnace chamber 1 of the fixed bed heating furnace is equipped with four horizontal perforated sieve plates. CMS is laid flat on the perforated sieve plates to form four beds 2 arranged from top to bottom. The thickness of the bed 2 is 40cm (the basis for choosing a thickness of 40cm is that this thickness can maximize the utilization rate of the unit furnace space while ensuring the uniformity of deposition, and take into account both production efficiency and product quality). The upper and lower sides of the bed 2 are formed with an overhead layer 3, the height of which is 10cm. In order to facilitate the loading and unloading of materials, an openable refractory sealing door can be set on the side wall of the furnace chamber 1.

[0035] Each elevated layer 3 is equipped with an air inlet pipe 5, and the top and bottom of the furnace 1 are equipped with exhaust valves 4, the air inlet end of the exhaust valve 4 being connected to the corresponding elevated layer 3. The air inlet pipe 5 is repeatedly bent in the horizontal direction, and the top and bottom of the air inlet pipe 5 are equipped with multiple air holes 9, each with a diameter of 1mm and a spacing of 6cm between adjacent holes. The multiple air holes 9 are evenly distributed horizontally in the elevated layer 3 to achieve uniform and large-area air supply. The outlet of the exhaust valve 4 and the air inlet end of the air inlet pipe 5 are located on the outside of the heating furnace.

[0036] The outer side of the furnace 1 is equipped with a controller 10, a first gas source 11, a second gas source 12, and a gas mixer 15. The first gas source 11 provides a high-pressure carrier gas, such as nitrogen, and the second gas source 12 provides a high-pressure carbon source gas, such as methane. The first gas source 11 and the second gas source 12 are connected to the two inlets of the gas mixer 15 through a first valve 13 and a second valve 14, respectively. The outlet of the gas mixer 15 is connected to two fourth valves 8 through a reversing valve 7. The two fourth valves 8 are connected to the air inlet pipe 5 located at the bottom of the furnace 1 and the air inlet pipe 5 located at the top of the furnace 1, respectively. The reversing valve 7 is a three-way valve with flow control function. The remaining air inlet pipes 5 are connected to the second gas source 12 through three fifth valves 6. The first gas source 11 is connected to the bottommost air inlet pipe 5 through a third valve 16. The first valve 13, the second valve 14, the fifth valve 6, and the third valve 16 are all connected to the signal output terminal of the controller 10. The controller preferably uses the FX3U model, which has a sufficient number of ports (to meet the independent connection requirements of each valve, sensor, and heating element), high control accuracy, and is suitable for the automation control requirements of this process.

[0037] Each elevated floor 3 is equipped with a temperature compensation mechanism connected to the controller 10, ensuring that the temperature difference between each elevated floor 3 is less than 5°C. The temperature compensation mechanism includes a temperature sensor 17 and a linear heating element 18, which can be an electric heating wire. The heating element 18 is fixed to the air intake pipe 5, which is made of aluminum or copper. A concentration sensor 19 is installed in each elevated floor 3 to detect the concentration of the carbon source gas. Both the temperature sensor 17 and the concentration sensor 19 are connected to the signal input terminal of the controller 10, and the heating element 18 is connected to the signal output terminal of the temperature sensor 17. In this embodiment, each valve, heating element, temperature sensor, and concentration sensor independently occupies one port of the controller; there is no sharing.

[0038] S2. Carrier gas is introduced into furnace 1 to purge the air inside. Specifically: controller 10 opens the third valve 16 and the highest exhaust valve 4, while the other exhaust valves 4 are closed. Carrier gas enters the bottom of furnace 1 from the first gas source 11, and the air is discharged from the highest exhaust valve 4. After purging the air, controller 10 closes all valves, or keeps only the highest exhaust valve 4 at a very small opening, to prevent excessive pressure during subsequent heating of furnace 1.

[0039] S3. The furnace chamber 1 is heated to 800℃. The temperature of the corresponding overhead layer 3 is detected by the temperature sensor 17. When the temperature is lower than 800℃, the controller 10 activates the corresponding heating element 18 to ensure that the temperature difference between the various overhead layers is less than 3℃. The heat from the heating element 18 is dissipated more quickly through the air intake pipe 5.

[0040] S4. Controller 10 opens the first valve 13 and the second valve 14. The carbon source gas and the carrier gas are mixed in the gas mixer 15 at a volume ratio of 1:4 to obtain the reaction gas. The reaction gas is introduced into the furnace 1, and a reaction gas flow is formed in the furnace 1. The reaction gas flow alternately switches its direction and passes vertically through the bed 2 until the reaction is completed.

[0041] Specifically: the reaction time is 100 minutes, the airflow alternation period is 10 minutes, and when the airflow is upward in the furnace 1, the main air source for the reaction gas is the air inlet pipe 5 at the bottom of the furnace 1. The controller keeps the third valve 16 of the air inlet pipe 5 at the bottom of the furnace 1 fully open, closes the bottom exhaust valve 4, and opens the top exhaust valve 4. The controller also uses the reversing valve 7 to disconnect the gas mixer 15 from the top overhead layer 3 and connect it to the bottom overhead layer 3. The reaction gas flows into the bottom of the furnace 1, passes through each bed layer 2 from top to bottom, and the reaction tail gas is discharged from the top exhaust valve 4. During this process, the controller detects the temperature of each overhead layer 3 through the temperature sensor 17, maintains the temperature difference of each overhead layer 3 to less than 3°C through the heating elements 18, detects the concentration of carbon source gas in each overhead layer 3 through the concentration sensors 19, and controls the opening of the fifth valve 6 to keep the concentration of carbon source gas in each overhead layer 3 similar, with the concentration difference kept within 5%.

[0042] When the airflow is downward in the furnace 1, the main air source for the main reactant gas is the air intake pipe 5 at the top of the furnace 1. The controller makes the third valve 16 of the air intake pipe 5 at the top of the furnace 1 fully open, closes the exhaust valve 4 at the top, and opens the exhaust valve 4 at the bottom. The controller makes the reversing valve 7 disconnect the gas mixer 15 from the bottom overhead layer 3 and connect it to the top overhead layer 3. The reactant gas enters from the top of the furnace 1 and leaves from the bottom of the furnace 1. The principle is basically the same as when the airflow is upward in the furnace 1, except that the airflow direction is reversed.

[0043] S5. After the reaction is complete, the controller opens the third valve 13 and the top exhaust valve, while closing the other valves. Nitrogen gas is introduced at a high flow rate from the bottom of furnace 1 and exits from the top of furnace 1, carrying away heat and reducing the temperature of furnace 1 to below 300°C within 10 minutes, thus obtaining the finished product. Rapid cooling helps to quickly cut off the continued reaction, thereby reducing the dispersion within the same batch.

[0044] Testing revealed that the dispersion of the finished CMS was 22%, allowing for deposition reactions on multiple beds in a single operation, resulting in high output and efficiency.

[0045] Comparative example: Using an existing fixed-bed heating furnace with a single 50cm thick bed, no airflow switching, CMS dispersion of 37%, low output, and low efficiency.

[0046] In the description of the embodiments, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations.

Claims

1. A gas conditioning process for carbon molecular sieve carbon deposition reaction, characterized in that: Includes the following steps, S1. Spread CMS flat into the furnace chamber (1) of the fixed bed heating furnace to form a horizontal bed (2), with a bed thickness ≤ 50cm; S2. Introduce carrier gas into the furnace (1) and vent the air in the furnace (1); S3, the furnace (1) is heated to 800±50℃; S4. Mix the carbon source gas and the carrier gas to obtain the reaction gas. Pass the reaction gas into the furnace (1) to form a reaction gas flow in the furnace (1). The reaction gas flow alternately switches the flow direction and passes vertically through the bed (2) until the reaction ends. S5. A large flow of carrier gas passes through the furnace (1), reducing the temperature of the furnace (1) to below 300℃ within 10 minutes, thus obtaining the finished product.

2. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 1, characterized in that: In step S4, the time interval between the alternating flow direction of the reaction gas flow is 5-10 minutes, and the number of times the reaction gas flow passes through the bed (2) from top to bottom is the same as the number of times it passes through the bed (2) from bottom to top.

3. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 1, characterized in that: The furnace (1) is provided with multiple bed layers (2) arranged from top to bottom. The upper and lower sides of the bed layers (2) form an overhead layer (3). Each overhead layer (3) is provided with an air inlet pipe (5). The top and bottom of the furnace (1) are provided with a smoke exhaust valve (4). The outlet of the smoke exhaust valve (4) and the air inlet end of the air inlet pipe (5) are located outside the heating furnace.

4. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 3, characterized in that: The intake pipe (5) is repeatedly bent in the horizontal direction, and multiple air holes (9) are provided at the top and bottom of the intake pipe (5).

5. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 3, characterized in that: The outer side of the furnace (1) is provided with a controller (10), a first gas source (11), a second gas source (12) and a gas mixer (15). The first gas source (11) provides carrier gas, and the second gas source (12) provides carbon source gas. The first gas source (11) and the second gas source (12) are connected to the two inlets of the gas mixer (15) through the first valve (13) and the second valve (14) respectively. The outlet of the gas mixer (15) is connected to two fourth valves (8) through the reversing valve (7). The two fourth valves (8) are connected to the air inlet pipe (5) located at the bottom of the furnace (1) and the air inlet pipe (5) located at the top of the furnace (1) respectively. The remaining air inlet pipes (5) are connected to the second gas source (12) through the fifth valve (6). The first gas source (11) is connected to the bottom air inlet pipe (5) through the third valve (16). The first valve (13), the second valve (14), the fifth valve (6) and the third valve (16) are all connected to the signal output terminal of the controller (10).

6. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 5, characterized in that: Each of the elevated floors (3) is equipped with a temperature compensation mechanism connected to the controller (10) so that the temperature difference of each elevated floor (3) is less than 5°C.

7. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 6, characterized in that: The temperature compensation mechanism includes a temperature sensor (17) and a linear heating element (18). The temperature sensor (17) is connected to the signal input terminal of the controller (10), and the heating element (18) is connected to the signal output terminal of the temperature sensor (17).

8. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 7, characterized in that: The heating element (18) is fixed to the air intake pipe (5), which is made of aluminum or copper.

9. The carbon molecular sieve carbon deposition reaction gas conditioning process according to claim 3, characterized in that: A concentration sensor (19) for detecting the concentration of carbon source gas is installed in each elevated floor (3), and the concentration sensor (19) is connected to the controller (10).

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