Waste gas recovery system for producing carbon nanotubes by vapor deposition method and recovery method thereof

Abstract

The invention relates to a system and a method for recovering waste gas generated in production of carbon nanotubes by a vapor deposition method. The waste gas recovery system is technically characterized by comprising a waste gas pipeline, a waste gas cooling device, a waste gas solid separation device, a waste gas static separator, a gas pressurization device, a gas decompression device, a hydrogen membrane separation device, a hydrocarbon gas and nitrogen membrane separation device and a multi-type sensor for collecting the working condition of the recovery system, the equipment controller is used for controlling equipment on the recovery system; the waste gas recovery control server controls the pressure on the two sides of a separation membrane of the hydrogen membrane separation device and the pressure on the two sides of a separation membrane of the hydrocarbon gas and nitrogen membrane separation device to achieve the gas separation function, the pressure on high-risk gas is reduced, and the raw material hydrocarbon gas, the working gas nitrogen and the derivative gas hydrogen in the waste gas can be separated out and reused. And the requirements of energy conservation, emission reduction and efficiency improvement on the premise of safe production are met.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon nanotube production, in particular to a waste gas recovery system and a recovery method for carbon nanotubes produced by a vapor deposition method. Background Art

[0002] As we all know, newly developed or developing structural materials with excellent performance and functional materials with special properties are called new materials. Carbon nanotubes, which were discovered in the 1990s, have attracted widespread attention for their excellent performance. After entering the 21st century, with the mass production of carbon nanotubes, carbon nanotubes have gradually become one of the important new materials.

[0003] The vapor deposition method is a commonly used method in the field of chemical production and is also a commonly used method for carbon nanotube production. The carbon-containing gas raw material is converted into carbon nanotubes in a production equipment in a specific environment, and the unconverted carbon-containing gas raw material is discharged at the same time. When hydrocarbons are used as raw materials and nitrogen is used as working and protective gases, the waste gas contains raw hydrocarbon gas, nitrogen, hydrogen and a small amount of other impurities. How to separate the valuable raw gas from the waste gas and reuse it is an urgent problem that needs to be solved at present. Due to the high-risk, flammable and explosive dangerous goods of the raw hydrocarbon gas and hydrogen in the waste gas, it is not suitable to separate them through a separation membrane with too much pressure, especially when the two are mixed together, which increases the danger of the waste gas. Due to the high-risk nature of the waste gas, it is difficult to handle. The usual practice is to burn these high-risk waste gases. In fact, the main components of the waste gas are valuable raw hydrocarbon gas, hydrogen and nitrogen. The combustion treatment method not only pollutes the environment but also wastes resources. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a waste gas recovery system and a recovery method for the production of carbon nanotubes by vapor deposition, which can effectively separate the raw hydrocarbon gas, hydrogen and nitrogen in the waste gas, and achieve the goal of energy saving, emission reduction and efficiency improvement under the premise of safe production.

[0005] The present invention solves the existing technical problems by adopting the following technical solutions:

[0006] A waste gas recovery system for producing carbon nanotubes by vapor deposition method, comprising a waste gas pipeline, a waste gas cooling device, a waste gas solid separation device, a waste gas static separator, a gas pressurizing device, a gas decompression device, a hydrogen membrane separation device, a hydrocarbon gas and nitrogen membrane separation device, multiple types of sensors for collecting the working conditions of the recovery system, a device controller for controlling the equipment on the recovery system, and a waste gas recovery control server; the waste gas cooling device and the waste gas solid separation device are sequentially installed in the waste gas pipeline to cool the waste gas and perform solid-gas separation treatment, and the treated waste gas enters The static separator of the waste gas installed in the static separation zone performs static separation on the waste gas. The separated hydrogen enters the hydrogen membrane separation device in the hydrogen membrane separation zone through the gas pressurizing device. The hydrogen membrane separation device is connected to the hydrogen storage device through the gas decompression device. The hydrogen membrane separation device performs hydrogen separation under the joint action of the gas pressurizing device and the gas decompression device. The separated hydrogen is sent to the hydrogen storage device for hydrogen collection. The separated hydrocarbon gas, nitrogen mixed gas and residual hydrogen enter the hydrogen storage device installed in the residual hydrogen separation zone through the gas pressurizing device. A gas membrane separation device, wherein the hydrogen membrane separation device is connected to the hydrogen gas storage device through a gas decompression device, and the hydrogen membrane separation device separates the mixed gas under the joint action of the gas pressurizing device and the gas decompression device, and the separated hydrogen is sent to the hydrogen gas storage device for hydrogen collection, and the separated hydrocarbon gas and nitrogen mixed gas enters the hydrocarbon gas and nitrogen membrane separation device installed in the hydrocarbon gas separation area through the gas pressurizing device, and the hydrocarbon gas and nitrogen membrane separation device is connected to the hydrocarbon gas storage device through the gas decompression device, and the hydrocarbon gas and nitrogen membrane separation device is connected to the nitrogen gas storage device through a pipeline The exhaust gas recovery control server is connected to the above-mentioned sensor and the equipment controller, and the sensor collects the operating condition information of the recovery system and transmits it to the exhaust gas recovery control server. The exhaust gas recovery control server controls the gas pressure increasing equipment, the gas pressure reducing equipment and the valves on the exhaust gas pipeline of the recovery system through the equipment controller.

[0007] Furthermore, the installation structure of the hydrogen membrane separation device in the hydrogen membrane separation area is as follows: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and a gas pressure reducing device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet. The above-mentioned gas pressurizing device and gas pressure reducing device are respectively connected to the device controller, and sensors for detecting working conditions are installed on the pipelines of the hydrogen membrane separation device and the gas pressurizing device and the gas pressure reducing device. The exhaust gas recovery control server controls the gas pressurizing device and the gas pressure reducing device according to the working conditions detected by the sensors, so that different pressure differences are formed on both sides of the gas separation membrane for hydrogen separation.

[0008] Furthermore, the installation structure of the hydrogen membrane separation device in the residual hydrogen membrane separation area is as follows: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and a gas pressure reducing device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet. The above-mentioned gas pressurizing device and gas pressure reducing device are respectively connected to the device controller, and sensors for detecting working conditions are installed on the pipelines of the hydrogen membrane separation device and the gas pressurizing device and the gas pressure reducing device. The exhaust gas recovery control server controls the gas pressurizing device and the gas pressure reducing device according to the working conditions detected by the sensors, so that different pressure differences are formed on both sides of the gas separation membrane for hydrogen separation.

[0009] Furthermore, the installation structure of the hydrocarbon gas and nitrogen membrane separation device in the hydrocarbon gas separation is as follows: a gas pressurizing device is installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the hydrogen membrane separation device, and a gas pressure reducing device is installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the hydrocarbon gas outlet. The above-mentioned gas pressurizing device and gas pressure reducing device are respectively connected to the device controller, and a control valve, a one-way valve and a flow control fan are successively installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the nitrogen outlet. Sensors for detecting working conditions are installed on the pipelines of the hydrocarbon gas and nitrogen membrane separation device and the gas pressurizing device and the gas pressure reducing device. The exhaust gas recovery control server controls the gas pressurizing device and the gas pressure reducing device according to the working conditions detected by the sensors, so that the gas forms different pressure differences on both sides of the gas separation membrane to separate the hydrocarbon gas.

[0010] Furthermore, the gas pressurizing equipment includes a control valve, a one-way valve and a compression fan installed in sequence; the gas decompression equipment includes a decompression fan, a one-way valve, a control valve and a flow control fan installed in sequence, and the control valve and the one-way valve are used to control the flow direction and flow of the gas.

[0011] Furthermore, the sensors are installed in the hydrogen separation zone, the residual hydrogen separation zone, the nitrogen separation zone and the exhaust gas pipeline, including gas flow, hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, raw hydrocarbons, VOC, air particles, temperature, humidity, pressure sensors and electric power sensors, and the sensors are connected to the exhaust gas recovery control server through an industrial bus; the equipment controller is installed on the gas pipeline valve, gas pressurization equipment and gas decompression equipment, and is connected to the exhaust gas recovery control server through an industrial bus.

[0012] Furthermore, the exhaust gas recovery control server is also connected to a remote management computer or smart phone via a local area network, a wide area network connector or a wide area network, and performs two-way communication via a data communication interface.

[0013] Furthermore, an emergency discharge device is installed on the control valve, gas pressurizing equipment and gas decompression equipment on the exhaust gas pipeline, and the emergency discharge device includes an emergency discharge pipeline, a channel opening / closing valve, an exhaust gas discharge combustion tower, and an emergency nitrogen filling and cleaning mechanism; a safety control linkage valve is installed at the inlet of the exhaust gas pipeline to discharge the exhaust gas from the carbon nanotube production line to the safety discharge combustion tower.

[0014] A method for recovering waste gas from carbon nanotubes produced by vapor deposition method comprises the following steps:

[0015] Step 1, the waste gas generated in the process of producing carbon nanotubes, including raw hydrocarbon gas, working gas nitrogen and derived gas hydrogen, is cooled by a waste gas cooling device, and solid-gas separation is performed by a waste gas solid separation device to obtain a mixed gas suitable for gas separation conditions and send it to a static separation device;

[0016] Step 2: The static separation equipment uses a natural gravity method to separate the mixed gas, and the separated hydrogen is sent to the hydrogen separation zone, and the separated hydrocarbon gas and nitrogen mixed gas is sent to the residual hydrogen separation zone;

[0017] Step 3: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the gas separation membrane and form different pressure differences to achieve the hydrogen separation function. The separated hydrogen is sent to the hydrogen storage device, and the residual hydrogen is sent to the residual hydrogen separation zone;

[0018] Step 4: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the residual hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the gas separation membrane and form different pressure differences to achieve the hydrogen separation function. The separated hydrogen is sent to the hydrogen storage device, and the separated hydrocarbon gas and nitrogen mixed gas is sent to the hydrocarbon separation zone;

[0019] Step 5, the waste gas recovery control server controls the gas pressurizing equipment and the gas decompression equipment on both sides of the hydrocarbon gas separation device in the hydrocarbon gas separation area, respectively applies positive and negative pressures to the gas on both sides of the gas separation membrane and forms different pressure differences, thereby realizing the hydrocarbon gas separation function. The separated hydrocarbon gas is sent to the hydrocarbon gas storage equipment, and the separated nitrogen is sent to the nitrogen gas storage equipment.

[0020] Furthermore, the waste gas recovery control server implements variable pressure control on the gas separation membrane. When the gas passes through the gas separation membrane, the pressure difference formed on both sides is: P = f (P 前 , P 后 ), where P 前 and P 后 Can be zero separately and simultaneously.

[0021] The advantages and positive effects of the present invention are:

[0022] 1. Aiming at the current situation that the waste gas generated by the production process of carbon nanotubes using hydrocarbon gas as raw material contains a mixed gas of hydrocarbon gas and hydrogen, which is a high-risk, flammable and explosive waste gas that is difficult to treat, the present invention adopts natural static and membrane separation technology to establish a waste gas recovery system, wherein the membrane separation method of applying positive and negative pressures on both sides of the separation membrane respectively reduces the pressure on the high-risk gas and avoids unsafe factors, and can separate the raw hydrocarbon gas, working gas nitrogen and derivative gas hydrogen in the waste gas and reuse them, wherein the hydrocarbon gas is used as production raw material again, the nitrogen is recycled, and the hydrogen is sold as an industrial product, fundamentally solving the waste gas emission problem of producing carbon nanotubes by vapor deposition method. The present invention not only reduces carbon emissions in the production process, but also creates considerable value, and meets the requirements of energy conservation, emission reduction and efficiency improvement under the premise of safe production.

[0023] 2. The present invention can diversify the raw materials for carbon nanotube production by separating and reusing the waste gas. The vapor deposition method for producing carbon nanotubes will try to select hydrocarbon gas with high carbon content and low hydrogen content as raw materials. The price of such hydrocarbon gas is higher than that of low carbon content and high hydrogen content. The present invention recovers the derivative hydrogen in the production of carbon nanotubes, which not only reduces the production cost, but also proposes a way to produce carbon nanotubes and hydrogen at the same time. For example, using low-priced methane CH4 as raw material, one carbon nanotube can also produce 1 / 3 of hydrogen at the same time, which not only increases the economic benefits, but also occupies a favorable technical position in the hydrogen energy era.

[0024] 3. By installing various types of sensors and equipment controllers on the waste gas recovery system, the present invention can not only automatically monitor and detect the working parameters of the production process, but also grasp the working conditions of the production equipment system in real time, and adjust the working parameters according to the instructions issued by the control system server to ensure efficient and safe production.

[0025] 4. The present invention connects the local management computer or the remote management computer and the intelligent terminal device through the local area network or wide area network technology, which can flexibly and effectively control the system and make it more convenient to use and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a connection diagram of the waste gas recovery system of the present invention. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0028] The present invention proposes a waste gas recovery system for producing carbon nanotubes by vapor deposition method, such as Figure 1 As shown, it includes exhaust gas pipelines, exhaust gas cooling devices, exhaust gas solid separation equipment, exhaust gas static separators, gas pressurizing equipment, gas decompression equipment, hydrogen membrane separation equipment, hydrocarbon gas and nitrogen membrane separation equipment, multiple types of sensors for collecting recovery system working conditions, equipment controllers for controlling equipment on the recovery system, and exhaust gas recovery control servers.

[0029] The waste gas cooling device and the waste gas solid separation device are sequentially installed in the waste gas pipeline inlet to cool the waste gas (raw hydrocarbon gas, working gas nitrogen and derived gas hydrogen) and perform solid-gas separation to obtain waste gas that meets the gas separation conditions. The treated waste gas enters the waste gas static separator installed in the static separation area. The waste gas static separator performs static separation on the waste gas, and the separated hydrogen enters the hydrogen membrane separation device in the hydrogen membrane separation area through the gas pressurizing device. The hydrogen membrane separation device is connected to the hydrogen storage device through the gas decompression device. The hydrogen membrane separation device performs hydrogen separation under the joint action of the gas pressurizing device and the gas decompression device. The hydrogen separated by the waste gas static separator is sent to the hydrogen storage device for hydrogen collection. The hydrocarbon gas, nitrogen mixed gas and residual hydrogen separated by the exhaust gas static separator enter the hydrogen membrane separation device installed in the residual hydrogen separation zone through the gas pressurizing equipment, and the hydrogen membrane separation device is connected to the hydrogen storage device through the gas pressure reducing equipment. The hydrogen membrane separation device separates the mixed gas under the joint action of the gas pressurizing equipment and the gas pressure reducing equipment, and the separated hydrogen is sent to the hydrogen storage device for hydrogen collection. The separated hydrocarbon gas and nitrogen mixed gas enters the hydrocarbon gas and nitrogen membrane separation device installed in the hydrocarbon separation zone through the gas pressurizing equipment, and the hydrocarbon gas and nitrogen membrane separation device is connected to the hydrocarbon storage device through the gas pressure reducing equipment. The hydrocarbon gas and nitrogen membrane separation device is connected to the nitrogen storage device through a one-way valve, a control valve and a flow control fan. The hydrocarbon gas and nitrogen membrane separation device separates the mixed gas under the action of the gas pressurizing equipment and the gas pressure reducing equipment, and the separated hydrocarbon gas is sent to the hydrocarbon storage device for hydrocarbon collection, and the separated nitrogen is sent to the nitrogen storage device for nitrogen collection. The waste gas recovery control server is connected to the above-mentioned sensors and equipment controllers through an industrial bus, collects operating information of the recovery system through sensors, and controls the gas pressurizing equipment, gas decompression equipment and valves on the waste gas pipeline of the recovery system through the equipment controller.

[0030] In order to increase the flexibility of recycling system control, the exhaust gas recovery control server is also connected to a remote management computer or smart phone through a LAN, WAN connector, and WAN, and performs two-way communication through a data communication interface, becoming part of the carbon nanotube production line.

[0031] An emergency discharge device is also installed on the control valve, gas pressurizing equipment and gas decompression equipment on the waste gas pipeline. The emergency discharge device includes an emergency discharge pipeline, a channel opening / closing valve, a waste gas discharge combustion tower, and an emergency nitrogen filling and cleaning mechanism. In an emergency, the waste gas recovery control server issues an action command to the emergency discharge device to complete the discharge work and resume production. When the emergency nitrogen filling and cleaning is started, nitrogen is filled into the carbon nanotube production and waste gas emission system to remove the raw hydrocarbon gas and hydrogen and other flammable gases in the production line equipment as soon as possible. When the emergency nitrogen is filled, the emergency control valve and the emission control device are in an open state, and the gas is discharged to the waste gas combustion emission tower.

[0032] The system can also be equipped with a safety control linkage valve at the inlet of the waste gas pipeline. When the waste gas recovery production system stops working, the waste gas introduction valve is closed and the safety control linkage valve is opened at the same time to direct the waste gas of the carbon nanotube production line to the emergency discharge device, so that the waste gas generated during the carbon nanotube production process is discharged to the safety discharge combustion tower, thereby ensuring safe production.

[0033] The waste gas cooling device and waste gas solid separation equipment in the system cool down the waste gas generated in the carbon nanotube production process and separate the gas and solid respectively. In this embodiment, the waste gas cooling device uses but is not limited to a high-efficiency partition wall heat exchanger to reduce the introduced high-temperature waste gas to a temperature suitable for the gas separation membrane; the waste gas cooling device uses but is not limited to a gas-solid two-phase filter, and a dual channel is set for equipment material replacement and maintenance.

[0034] The waste gas static separator in this system statically separates the waste gas treated by the waste gas cooling device and the waste gas solid separation equipment. At atmospheric pressure or slightly below atmospheric pressure, the mass difference of hydrogen, nitrogen and hydrocarbon gas is used to perform natural gravity separation on high-risk waste gas. The separated hydrogen enters the hydrogen separation zone, and the separated hydrocarbon and nitrogen mixed gas enters the residual hydrogen separation zone. After separation treatment by the static separator, the hydrocarbon content in the hydrogen can be greatly reduced, and the hydrogen content in the hydrocarbon and nitrogen mixed gas can be greatly reduced to ensure production safety.

[0035] In this embodiment, the hydrogen membrane separation device in the hydrogen separation zone adopts but is not limited to horizontal and tubular hydrogen membrane separation devices, and the pressure on both sides of the membrane is intelligently adjusted according to the hydrogen content in the exhaust gas, and a multi-stage device can be selected to achieve different recovery indicators. The specific installation method of the hydrogen membrane separation device is: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and the gas pressurizing device includes a control valve, a one-way valve and a compressor fan (air compressor) installed in sequence, and the above-mentioned gas pressurizing devices are respectively connected to the device controller connected to the online exhaust gas recovery control server, and a gas decompression device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet, and the gas decompression device includes a decompression fan (exhaust fan), a one-way valve, a control valve and a flow control fan installed in sequence, and the above-mentioned gas decompression devices are respectively connected to the device controller connected to the online exhaust gas recovery control server. The hydrogen membrane separation device and the pipelines of the gas pressurizing equipment and the gas decompression equipment are all equipped with sensors for detecting working conditions. The sensors are connected to the waste gas recovery control server and transmit the detected working condition data to the waste gas recovery control server, which controls the device controller. The hydrogen membrane separation device purifies the hydrogen separated by the waste gas static separator. The separated hydrogen enters the hydrogen storage device through the hydrogen outlet and becomes commercial hydrogen. The residual hydrogen gas that does not pass through the hydrogen separation membrane returns to the waste gas static separator. The principle of the hydrogen membrane separation device is as follows: the system control server sends instructions to the compressor fan and the steam extraction fan according to the hydrogen content in the mixed gas, controls the air compressor and the exhaust fan to form different pressure differences on both sides of the gas separation membrane, and then controls the gas flow direction and flow rate through the control valve and the one-way valve to adapt to the changes in gases with different contents. The gas pressure P on the separation membrane is P = P 前 -(-P 后 )=P 前 +P 后 The present invention aims at the hydrocarbon raw gas, hydrogen and nitrogen in the mixed gas, and the components are different in different production periods. The content of a certain component is zero in some periods. In the separation stage, variable pressure control is adopted to reduce system pressure and energy consumption. The pressure of high-risk gas when passing through the separation membrane is: P = f (P 前 , P 后 ), where P 前 and P 后 Can be zero separately and simultaneously.

[0036] In this embodiment, the hydrogen membrane separation device in the residual hydrogen separation zone adopts but is not limited to horizontal and tubular hydrogen membrane separation devices, and the pressure on both sides of the membrane is intelligently adjusted according to the hydrogen content in the exhaust gas, and a multi-stage device can be selected to achieve different recovery indicators. The specific installation method of the hydrogen membrane separation device is as follows: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and the gas pressurizing device includes a flow control fan, a control valve, a check valve and a compressor fan (air compressor) installed in sequence, and the above-mentioned gas pressurizing devices are respectively connected to the device controller connected to the online exhaust gas recovery control server; a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet, and the gas decompression device includes a decompression fan (exhaust fan), a check valve, a control valve and a flow control fan, and the above-mentioned gas decompression devices are respectively connected to the device controller connected to the online exhaust gas recovery control server. The pipelines of the hydrogen membrane separation device, gas pressurizing equipment, and gas decompression equipment are all equipped with sensors for detecting working conditions. The sensors are connected to the waste gas recovery control server, and transmit the detected working condition data to the waste gas recovery control server, which controls the device controller. The hydrogen membrane separation device separates the residual hydrogen in the hydrocarbon gas and nitrogen mixed gas separated by the waste gas static separator. The separated hydrogen enters the hydrogen storage device through the hydrogen outlet and becomes commercial hydrogen. The separated hydrocarbon gas and nitrogen mixed gas enters the hydrocarbon separation area. The principle of the hydrogen membrane separation device is as follows: the system control server sends instructions to the compressor fan and the steam extraction fan according to the hydrogen content in the mixed gas, controls the air compressor and the exhaust fan to form different pressure differences on both sides of the gas separation membrane, and then controls the gas flow direction and flow rate through the control valve and the one-way valve to adapt to the changes in gases with different contents. The gas pressure P on the separation membrane is P = P 前 -(-P 后 )=P 前 +P 后 , to adjust working conditions, work efficiency and safe production.

[0037] In this embodiment, the hydrocarbon gas and nitrogen membrane separation device installed in the hydrocarbon gas separation zone adopts but is not limited to horizontal and tubular hydrocarbon gas and nitrogen membrane separation devices, and the pressure on both sides of the membrane is intelligently adjusted according to the hydrocarbon gas and nitrogen content in the waste gas, and a multi-stage device can be selected to achieve different recovery indicators. The specific installation method of the hydrocarbon gas and nitrogen membrane separation device is as follows: a gas pressurizing device is installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the hydrogen membrane separation device, and the gas pressurizing device includes a control valve, a one-way valve and a compressor fan (air compressor) installed in sequence, and the above-mentioned gas pressurizing device is respectively connected to a device controller connected to the online waste gas recovery control server, and a gas decompression device is installed in the two pipelines between the hydrocarbon gas and nitrogen membrane separation device and the hydrocarbon gas outlet, and each gas decompression device includes a decompression fan (exhaust fan), a one-way valve, a control valve and a flow control fan installed in sequence, and the above-mentioned gas decompression equipment is respectively connected to a device controller connected to the online waste gas recovery control server. A control valve, a one-way valve and a flow control blower are installed in sequence in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the nitrogen outlet. Sensors for detecting working conditions are installed on the pipelines of the hydrogen membrane separation device, the gas pressurizing device and the gas decompression device. The sensors are connected to the waste gas recovery control server and transmit the detected working condition data to the waste gas recovery control server, which controls the device controller. The hydrocarbon gas and nitrogen membrane separation device separates hydrocarbon gas and nitrogen mixed gas separated in the residual hydrogen separation zone. The separated hydrocarbon gas enters the hydrocarbon gas storage device through the hydrocarbon gas outlet, and other impurity hydrocarbon gases are discharged together. After purification, they are used as raw materials. The separated nitrogen mixed gas enters the nitrogen gas storage device through the nitrogen outlet and is reused as the working gas for carbon nanotube production after purification. The principle of the hydrocarbon gas and nitrogen membrane separation device is as follows: the system control server sends instructions to the compressor and exhaust fan according to the hydrocarbon gas content in the mixed gas, controls the compressor and exhaust fan to form different pressure differences on both sides of the gas separation membrane, and then controls the gas flow direction and flow rate through the control valve and the one-way valve to adapt to the changes in gas with different contents. The gas pressure on the separation membrane is P = P 前 -(-P 后 )=P 前 +P 后 , to adjust working conditions, work efficiency and safe production.

[0038] In this embodiment, the sensors installed in the recovery system are installed in the hydrogen separation zone, the residual hydrogen separation zone, the nitrogen separation zone and the exhaust gas pipeline, including gas flow, hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, raw hydrocarbons, VOC, air particles, temperature, humidity, pressure sensors, and electric power sensors. The sensors are connected to the exhaust gas recovery control server through the industrial bus. The sensors collect the operating parameters of the production line in real time and collect the data to the exhaust gas recovery control server through the industrial bus. The control server standardizes, stores and gives an analysis report on the operating parameters.

[0039] In this embodiment, the equipment controller is installed on the gas pipeline valve, gas pressurizing equipment and gas decompression equipment, and is connected to the waste gas recovery control server through the industrial bus. The waste gas recovery control server issues action instructions to the equipment controller to adjust the operating conditions of each production line, thereby realizing intelligent control and management of production.

[0040] Based on the above waste gas recovery system for producing carbon nanotubes by vapor deposition method, the present invention also proposes a waste gas recovery method for producing carbon nanotubes by vapor deposition method, comprising the following steps:

[0041] Step 1: The waste gas generated during the production of carbon nanotubes, including raw hydrocarbon gas, working gas nitrogen and derivative gas hydrogen, is cooled by a waste gas cooling device, and solid-gas separation is performed by a waste gas solid separation device to obtain a mixed gas suitable for gas separation conditions and send it to a static separation device.

[0042] Step 2: The static separation equipment uses natural gravity to separate the mixed gas to obtain hydrogen and a mixed gas of hydrocarbon gas and nitrogen. The separated hydrogen is sent to the hydrogen separation zone, and the separated mixed gas of hydrocarbon gas and nitrogen is sent to the residual hydrogen separation zone.

[0043] Step 3: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the separation membrane, respectively, to form different pressure differences on both sides of the separation membrane. The gas pressure on the separation membrane is P = P 前 -(-P 后 )=P 前 +P 后 , realizing the hydrogen separation function, the separated hydrogen is sent to the hydrogen storage equipment, and the residual hydrogen is sent to the residual hydrogen separation area;

[0044] Step 4: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the residual hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the gas separation membrane, respectively, to form different pressure differences on both sides of the gas separation membrane. The gas pressure on the separation membrane is P = P 前 -(-P后 )=P 前 +P 后 , realizing the hydrogen separation function, the separated hydrogen is sent to the hydrogen storage equipment, and the separated hydrocarbon gas and nitrogen mixed gas is sent to the hydrocarbon gas separation area;

[0045] Step 5: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrocarbon gas separation device in the hydrocarbon gas separation zone to apply positive and negative pressures to the gas on both sides of the separation membrane, respectively, to form different pressure differences on both sides of the gas separation membrane. The gas pressure on the separation membrane is P = P 前 -(-P 后 )=P 前 +P 后 , realizing the hydrocarbon gas separation function, the separated hydrocarbon gas is sent to the hydrocarbon gas storage equipment, and the separated nitrogen is sent to the nitrogen gas storage equipment.

[0046] The present invention can efficiently and safely control the waste gas recovery, thereby greatly improving the production efficiency of carbon nanotubes. Propylene gas is used as the raw material for producing carbon nanotubes by the vapor deposition method. Theoretically, 1.167 tons of propylene are required to produce one ton of carbon nanotubes. According to the general production process conditions, a raw material conversion rate of 50% is required, and 2.334 tons of propylene are required. 1.167 tons of unconverted propylene and 0.167 tons of separated hydrogen are discharged. The process nitrogen consumption is about twice that of propylene, and the discharged nitrogen is 2 tons. The value of the three gases discharged is 12,469 yuan (7,000 yuan / ton for propylene, 480 yuan / ton for nitrogen, and 20,000 yuan / ton for hydrogen). According to the calculation of a production line with an annual output of 5,000 tons of carbon nanotubes, the value is 62.35 million yuan, which is equivalent to reducing the production cost by 25% (50,000 yuan / ton for carbon nanotubes).

[0047] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A waste gas recovery system for producing carbon nanotubes by vapor deposition, characterized in that: It includes an exhaust gas pipeline, an exhaust gas cooling device, an exhaust gas solid separation device, an exhaust gas static separator, a gas pressurizing device, a gas decompression device, a hydrogen membrane separation device, a hydrocarbon gas and nitrogen membrane separation device, multiple types of sensors for collecting the working conditions of the recovery system, a device controller for controlling the equipment on the recovery system, and an exhaust gas recovery control server; the exhaust gas cooling device and the exhaust gas solid separation device are sequentially installed in the exhaust gas pipeline to cool the exhaust gas and perform solid-gas separation treatment, and the treated exhaust gas enters the exhaust gas static separator installed in the static separation area The waste gas static separator performs static separation on the waste gas, and the separated hydrogen enters the hydrogen membrane separation device in the hydrogen membrane separation area through the gas pressurizing equipment. The hydrogen membrane separation device is connected to the hydrogen gas storage device through the gas decompression equipment. The hydrogen membrane separation device performs hydrogen separation under the joint action of the gas pressurizing equipment and the gas decompression equipment. The separated hydrogen is sent to the hydrogen gas storage device for hydrogen collection. The separated hydrocarbon gas, nitrogen mixed gas and residual hydrogen enter the hydrogen membrane separation device installed in the residual hydrogen separation area through the gas pressurizing equipment. The hydrogen membrane The separation device is connected to the hydrogen gas storage device through the gas pressure reducing device. The hydrogen membrane separation device separates the mixed gas under the joint action of the gas pressurizing device and the gas pressure reducing device. The separated hydrogen is sent to the hydrogen gas storage device for hydrogen collection. The separated hydrocarbon gas and nitrogen mixed gas enters the hydrocarbon gas and nitrogen membrane separation device installed in the hydrocarbon gas separation area through the gas pressurizing device. The hydrocarbon gas and nitrogen membrane separation device is connected to the hydrocarbon gas storage device through the gas pressure reducing device. The hydrocarbon gas and nitrogen membrane separation device is connected to the nitrogen gas storage device through a pipeline. The hydrocarbon gas and nitrogen membrane separation device separates the mixed gas under the action of the gas pressurizing equipment and the gas decompression equipment. The separated hydrocarbon gas is sent to the hydrocarbon gas storage equipment for hydrocarbon gas collection, and the separated nitrogen is sent to the nitrogen storage equipment for nitrogen collection; the waste gas recovery control server is connected to the above-mentioned sensor and equipment controller, the sensor collects the operating condition information of the recovery system and transmits it to the waste gas recovery control server, and the waste gas recovery control server controls the gas pressurizing equipment, gas decompression equipment and valves on the waste gas pipeline of the recovery system through the equipment controller.

2. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to claim 1, characterized in that: The installation structure of the hydrogen membrane separation device in the hydrogen membrane separation area is as follows: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and a gas decompression device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet. The above-mentioned gas pressurizing device and gas decompression device are respectively connected to the device controller, and sensors for detecting working conditions are installed on the pipelines of the hydrogen membrane separation device and the gas pressurizing device and the gas decompression device. The exhaust gas recovery control server controls the gas pressurizing device and the gas decompression device according to the working conditions detected by the sensors, so that different pressure differences are formed on both sides of the gas separation membrane for hydrogen separation.

3. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to claim 1, characterized in that: The installation structure of the hydrogen membrane separation device in the residual hydrogen membrane separation area is as follows: a gas pressurizing device is installed in the pipeline between the hydrogen membrane separation device and the static separator, and a gas decompression device is installed in the pipeline between the hydrogen membrane separation device and the hydrogen outlet. The above-mentioned gas pressurizing device and gas decompression device are respectively connected to the device controller, and sensors for detecting working conditions are installed on the pipelines of the hydrogen membrane separation device and the gas pressurizing device and the gas decompression device. The exhaust gas recovery control server controls the gas pressurizing device and the gas decompression device according to the working conditions detected by the sensors, so that different pressure differences are formed on both sides of the gas separation membrane for hydrogen separation.

4. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to claim 1, characterized in that: The installation structure of the hydrocarbon gas and nitrogen membrane separation device in the hydrocarbon gas separation is as follows: a gas pressurizing device is installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the hydrogen membrane separation device, and a gas pressure reducing device is installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the hydrocarbon gas outlet. The above-mentioned gas pressurizing device and gas pressure reducing device are respectively connected to the device controller, and a control valve, a one-way valve and a flow control fan are successively installed in the pipeline between the hydrocarbon gas and nitrogen membrane separation device and the nitrogen outlet. Sensors for detecting working conditions are installed on the pipelines of the hydrocarbon gas and nitrogen membrane separation device and the gas pressurizing device and the gas pressure reducing device. The exhaust gas recovery control server controls the gas pressurizing device and the gas pressure reducing device according to the working conditions detected by the sensors, so that different pressure differences are formed on both sides of the gas separation membrane for hydrocarbon gas separation.

5. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to claim 2, 3 or 4, characterized in that: The gas pressurizing equipment includes a control valve, a one-way valve and a compression blower installed in sequence; the gas decompression equipment includes a decompression blower, a one-way valve, a control valve and a flow control blower installed in sequence, and the control valve and the one-way valve are used to control the flow direction and flow of the gas.

6. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to any one of claims 1 to 4, characterized in that: The sensors are installed in the hydrogen separation zone, the residual hydrogen separation zone, the nitrogen separation zone and the exhaust gas pipeline, including gas flow, hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, raw hydrocarbons, VOC, air particles, temperature, humidity, pressure sensors and electric power sensors. The sensors are connected to the exhaust gas recovery control server through an industrial bus; the equipment controller is installed on the gas pipeline valve, gas pressurization equipment and gas decompression equipment, and is connected to the exhaust gas recovery control server through an industrial bus.

7. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to any one of claims 1 to 4, characterized in that: The waste gas recovery control server is also connected to a remote management computer or smart phone via a local area network, a wide area network connector or a wide area network, and performs two-way communication via a data communication interface.

8. The waste gas recovery system for producing carbon nanotubes by vapor deposition method according to any one of claims 1 to 4, characterized in that: An emergency discharge device is also installed on the control valve, gas pressurizing equipment and gas decompression equipment on the exhaust gas pipeline, and the emergency discharge device includes an emergency discharge pipeline, a channel opening / closing valve, an exhaust gas discharge combustion tower, and an emergency nitrogen filling and cleaning mechanism; a safety control linkage valve is installed at the inlet of the exhaust gas pipeline to discharge the exhaust gas from the carbon nanotube production line to the safety discharge combustion tower.

9. A method for recovering waste gas from a system for producing carbon nanotubes by vapor deposition as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, the waste gas generated in the process of producing carbon nanotubes, including raw hydrocarbon gas, working gas nitrogen and derived gas hydrogen, is cooled by a waste gas cooling device, and solid-gas separation is performed by a waste gas solid separation device to obtain a mixed gas suitable for gas separation conditions and send it to a static separation device; Step 2: The static separation equipment uses a natural gravity method to separate the mixed gas, and the separated hydrogen is sent to the hydrogen separation zone, and the separated hydrocarbon gas and nitrogen mixed gas is sent to the residual hydrogen separation zone; Step 3: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the gas separation membrane and form different pressure differences to achieve the hydrogen separation function. The separated hydrogen is sent to the hydrogen storage device, and the residual hydrogen is sent to the residual hydrogen separation zone; Step 4: The waste gas recovery control server controls the gas pressurizing equipment and gas decompression equipment on both sides of the hydrogen separation device in the residual hydrogen separation zone to apply positive and negative pressures to the gas on both sides of the gas separation membrane and form different pressure differences to achieve the hydrogen separation function. The separated hydrogen is sent to the hydrogen storage device, and the separated hydrocarbon gas and nitrogen mixed gas is sent to the hydrocarbon separation zone; Step 5, the waste gas recovery control server controls the gas pressurizing equipment and the gas decompression equipment on both sides of the hydrocarbon gas separation device in the hydrocarbon gas separation area, respectively applies positive and negative pressures to the gas on both sides of the gas separation membrane and forms different pressure differences, thereby realizing the hydrocarbon gas separation function. The separated hydrocarbon gas is sent to the hydrocarbon gas storage equipment, and the separated nitrogen is sent to the nitrogen gas storage equipment.

10. The method for recovering waste gas from a system for producing carbon nanotubes by vapor deposition according to claim 9, characterized in that: The waste gas recovery control server implements variable pressure control on the gas separation membrane. The pressure difference formed on both sides of the gas separation membrane is: P = f (P 前 , P 后 ), where P 前 and P 后 Can be zero separately and simultaneously.

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