A device for detecting the condensation characteristics of volatile organic compounds

Abstract

A device for detecting the desublimation characteristics of volatile organic compounds includes an exhaust gas configuration part, a cryogenic part, a bypass part, a rewarming part, and first and second organic concentration detection ports. The exhaust gas configuration part includes an air source, an organic saturator, and an organic filter. The air source is connected to the organic saturator, and the outlet of the organic saturator is connected to the inlet of the organic filter. The cryogenic part includes a precooling heat exchanger, a vortex tube, and a capture condensation tank; the hot side inlet of the precooling heat exchanger is connected to the outlet of the organic filter, the hot side outlet of the precooling heat exchanger is connected to the cold side inlet of the vortex tube, and the cold side outlet of the vortex tube is connected to the inlet of the capture condensation tank. The bypass part includes a bypass pipeline, and the air source is connected to the cold side inlet of the precooling heat exchanger through the bypass pipeline. The rewarming part includes a rewarming heat exchanger; the cold side inlet of the reset heat exchanger is connected to the outlet of the capture condensation tank, and the hot side inlet of the reset heat exchanger is used to input heat medium. The present invention can detect the desublimation characteristics of volatile organic compounds.

Description

Technical Field

[0001] The invention relates to the field of low-temperature condensation degree test devices, in particular to a volatile organic matter condensation characteristic detection device. Background Art

[0002] Exhaust gas contains volatile organic compounds, which are the main source of air pollution. Exhaust gas treatment has always been a concern of the country and enterprises. The national environmental protection standards are becoming more and more stringent, and the requirements for exhaust gas treatment processes are also becoming more stringent. The existing volatile organic compound treatment processes include condensation, adsorption, thermal cracking, cryogenics, etc.

[0003] The condensation method is suitable for tail gas with high concentration of volatile organic compounds, but has poor effect on low concentration tail gas. The adsorption method is suitable for low concentration tail gas, but the tail gas often contains a variety of organic components. It is difficult to completely desorb all organic components during the regeneration of the adsorbent. Therefore, there is a problem of fast deactivation of the adsorbent and the difficulty in handling the deactivated adsorbent. The thermal cracking method can effectively treat low concentration tail gas, but there are problems of high consumption, high cost, and inability to recover organic matter. The cryogenic method utilizes the characteristics of organic matter sublimation at low temperature, and uses the expansion of tail gas to cool it down. After the tail gas is reduced to an extremely low temperature, it is captured in a hot melt condensation box and then the organic matter is removed. It can better solve the problems of the previous processes and can also recover organic matter. However, the cryogenic method requires the mastery of the sublimation and crystallization of organic matter at extremely low temperatures, as well as data such as gas-solid phase equilibrium. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a volatile organic compound desublimation characteristic detection device, which can detect the desublimation characteristics of volatile organic compounds at low temperatures.

[0005] A volatile organic compound desublimation characteristic detection device according to an embodiment of the present invention comprises an exhaust gas configuration part, a cryogenic part, a bypass part, a rewarming part, a first organic compound concentration detection port and a second organic compound concentration detection port; the exhaust gas configuration part comprises an air source, an organic compound saturator and an organic compound filter, the air source is connected to the organic compound saturator, the outlet of the organic compound saturator is connected to the inlet of the organic compound filter; the organic compound saturator is filled with liquid-phase volatile organic compounds; the cryogenic part comprises a precooling heat exchanger, a vortex tube and a capture condensation tank; the hot side inlet of the precooling heat exchanger is connected to the outlet of the organic compound filter, the hot side outlet of the precooling heat exchanger is connected to the cold side inlet of the vortex tube, the cold side outlet of the vortex tube is connected to the inlet of the capture condensation tank, and a control valve is provided at the hot side outlet of the vortex tube; The part includes a bypass pipeline; the gas source is connected to the cold side inlet of the precooling heat exchanger through the bypass pipeline; the gas entering the cold side inlet of the precooling heat exchanger is used for heat exchange with the organic mixed gas entering the hot side inlet of the precooling heat exchanger; the rewarming part includes a rewarming heat exchanger; the cold side inlet of the reset heat exchanger is connected to the outlet of the capture condensation box, and the hot side inlet of the reset heat exchanger is used to input heat medium, and the heat medium is used to heat exchange with the organic mixed gas entering the cold side inlet of the reset heat exchanger; the first organic concentration detection port is respectively connected to the outlet of the organic filter and the hot side inlet of the precooling heat exchanger, and the second organic concentration detection port is connected to the cold side outlet of the reset heat exchanger; the first organic concentration detection port and the second organic concentration detection port are respectively used to access an external concentration detection device.

[0006] Preferably, dry ice is provided in the precooling heat exchanger; the capture condensation box is entirely immersed in a container filled with dry ice, and heat preservation is achieved by the dry ice.

[0007] The present invention has at least the following advantages:

[0008] 1. The embodiment of the present invention can detect the desublimation characteristics of volatile organic compounds at low temperatures, providing theoretical support for the design of cryogenic process;

[0009] 2. The embodiment of the present invention can easily obtain very low temperature gas through the cooperation of dry ice and vortex tube, and can detect the condensation characteristics of most volatile organic compounds at low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic structural diagram of a volatile organic compound desublimation characteristic detection device according to an embodiment of the present invention is shown.

[0011] Figure 2 Shows Figure 1 A local enlarged schematic diagram of part P. DETAILED DESCRIPTION

[0012] The present invention is described in detail below in conjunction with specific embodiments, but this is not intended to limit the present invention.

[0013] Figure 1 FIG. 1 is a schematic diagram showing the structure of a device for detecting the desublimation characteristics of volatile organic compounds according to an embodiment of the present invention. Figure 1 As shown, a volatile organic compound desublimation characteristic detection device according to an embodiment of the present invention includes an exhaust gas configuration part, a deep cooling part, a bypass part, a rewarming part, a first organic compound concentration detection port and a second organic compound concentration detection port.

[0014] The tail gas configuration part includes a gas source 1, an organic matter saturator 2 and an organic matter filter 3. The gas source 1 is connected to the organic matter saturator 2, and the outlet of the organic matter saturator 2 is connected to the inlet of the organic matter filter 3.

[0015] In this embodiment, the gas source 1 is cylinder nitrogen. In other embodiments, according to the properties of volatile organic compounds, dried compressed air can also be selected as the gas source.

[0016] The organic saturator 2 is filled with liquid-phase volatile organic matter. In the present embodiment, the volatile organic matter is cyclohexane. In other embodiments, the volatile organic matter may also be benzene, toluene, xylene, etc. according to different working conditions. The organic saturator 2 includes a shell 21. The outer shape of the shell 21 includes but is not limited to a cylinder, a cube, a cuboid, a cone, etc. In the present embodiment, a cylindrical shape is adopted for the convenience of processing. The shell 21 has an inner cavity 20 for storing liquid-phase volatile organic matter. A wire mesh demister 22 is provided on the upper part of the inner cavity 20. The outlet 28 of the organic saturator is connected to the inner cavity 20 and is located above the wire mesh demister 22. An air inlet pipeline 23 is provided at the bottom of the inner cavity 20. One end of the air inlet pipeline 23 is connected to the gas source 1, and the other end of the air inlet pipeline 23 is closed. A plurality of air outlet holes 231 are provided on the side of the air inlet pipeline 23 (please refer to Figure 2 ). Optionally, the plurality of air outlet holes 231 are evenly distributed, and the diameter of each air outlet hole is 0.2 cm to 0.5 cm, so as to ensure even distribution of the air intake.

[0017] Furthermore, the tail gas configuration part includes a temperature control device 9, which is used to control the temperature of the mixed gas (a mixture of nitrogen and cyclohexane in this embodiment) output from the organic saturator outlet 28. The temperature control device 9 can be a water bath device, an oil bath device, or a sand bath device, and the lower part of the organic saturator 2 is placed in the water bath device, the oil bath device, or the sand bath device. In this embodiment, the temperature control device is a water bath device, and the water bath device 9 has no top cover, and ice or water can be placed inside, so that the gas temperature at the outlet of the organic saturator 2 is controlled at the design temperature.

[0018] In this embodiment, the organic matter filter 3 can filter out liquid organic matter with a diameter of more than 20 μm.

[0019] The cryogenic part includes a precooling heat exchanger 4, a vortex tube 5 and a capture condensation tank 6. The hot side inlet of the precooling heat exchanger 4 is connected to the outlet of the organic filter 3, the hot side outlet of the precooling heat exchanger 4 is connected to the inlet of the vortex tube 5, the cold side outlet 56 of the vortex tube 5 is connected to the inlet 67 of the capture condensation tank 6, and a control valve is provided at the hot side outlet 58 of the vortex tube 5 (not shown in the figure, the control valve is provided at the hot side outlet of the vortex tube 5 is a prior art), and the flow rate and temperature of the airflow output from the cold side outlet 56 and the hot side outlet 58 of the vortex tube 5 can be adjusted by controlling the control valve.

[0020] In this embodiment, the precooling heat exchanger 4 is a coil heat exchanger with a cylindrical shape, which has the advantages of good heat exchange effect and long gas residence time. In other embodiments, the precooling heat exchanger 4 can also be a shell and tube heat exchanger or a U-tube heat exchanger.

[0021] Preferably, dry ice is provided in the precooling heat exchanger 4. The melting point of dry ice is -78.5°C. By adding dry ice into the precooling heat exchanger 4 and purging it with nitrogen, the organic mixed gas can be reduced to a sufficiently low temperature. The vortex tube 5 selected in this embodiment has a temperature reduction effect of not less than 30°C, and can reach a minimum of -80°C when the intake air temperature is guaranteed.

[0022] In this embodiment, the capture condensation box 6 includes a box body 61. The shape of the box body 61 includes but is not limited to a rectangular parallelepiped, a cube, a cylinder, etc. For the purpose of convenient processing, this embodiment adopts a rectangular parallelepiped shape. The box body 61 is provided with a chamber 60. A plurality of transverse baffles 62 are arranged in the chamber 60 in a staggered manner from left to right or from front to back. The plurality of transverse baffles 62 are arranged from top to bottom and are detachable. The material of the baffle 62 includes but is not limited to stainless steel, carbon steel, plastic, cardboard, etc. A filter screen 63 is also detachably provided in the chamber 60. The filter screen 63 is arranged above the plurality of transverse baffles 62 and is detachable and replaceable. The outlet 68 of the capture condensation box 6 is arranged above the filter screen 63, and the inlet 67 of the capture condensation box 6 is arranged below the plurality of transverse baffles 62. Preferably, the capture condensation box 6 is entirely immersed in a container (not shown in the figure) filled with dry ice, and the dry ice is used to achieve heat preservation.

[0023] The bypass part includes a bypass pipe 7, and the gas source 1 is connected to the cold side inlet of the precooling heat exchanger 4 through the bypass pipe 7. The gas entering the cold side inlet of the precooling heat exchanger 4 is used for heat exchange with the organic mixed gas entering the hot side inlet of the precooling heat exchanger 4.

[0024] The rewarming part includes a rewarming heat exchanger 8. The cold side inlet 85 of the rewarming heat exchanger 8 is connected to the outlet 68 of the capture condensation tank 6, and the hot side inlet 87 of the rewarming heat exchanger 8 is used to input a heat medium, which is used to perform heat exchange with the organic mixed gas entering the cold side inlet 85. The heat medium can be air or water. The hot side outlet 88 of the rewarming heat exchanger 8 is also shown in the figure.

[0025] In this embodiment, the rewarming heat exchanger 8 is a coil heat exchanger. In other embodiments, a shell-and-tube heat exchanger or a U-tube heat exchanger can be used instead, or other rewarming forms can be used, including but not limited to a jacket, a water bath, an oil bath, etc.

[0026] The first organic matter concentration detection port 101 is connected to the outlet of the organic matter filter 3 and the hot side inlet of the precooling heat exchanger 4, respectively, and the second organic matter concentration detection port 102 is connected to the cold side outlet 86 of the reset heat exchanger 8; the first organic matter concentration detection port 101 and the second organic matter concentration detection port 102 are respectively used to connect to an external concentration detection device. A temperature detection device is respectively provided at the outlet of the organic matter saturator 3, the inlet of the vortex tube 5 and the cold side outlet of the vortex tube 5, and the temperature detection device is, for example, a temperature transmitter.

[0027] The working process of the volatile organic compound desublimation characteristic detection device according to the embodiment of the present invention is roughly as follows.

[0028] The cylinder nitrogen is used as the gas source of the whole system and is divided into two routes. One route is used as a purge gas to enter the precooling heat exchanger 4 to purge the dry ice, accelerate the sublimation of the dry ice and obtain cooling capacity; the other route is used as a simulated exhaust gas to enter the organic saturator 2, and after fully contacting with the liquid phase organic matter, the liquid droplets are removed by the wire mesh demister 22 and the organic filter 3, and then enter the precooling heat exchanger 4 to cool to -40 to -50 ° C, and then enter the vortex tube 5 to expand and do work, and obtain a deep cold gas with a temperature of -50 to -80 ° C. At this time, the gas phase organic matter contained in it undergoes condensation and crystallization on the pipe wall along the way. The simulated exhaust gas after deep cooling enters the capture condensation box 6 for free sedimentation, and the unsettled cyclohexane particles are filtered through the filter 63, and then the organic mixed gas enters the reheating heat exchanger 8 to exchange heat with the circulating water to 0 to 20 ° C, and then the cyclohexane concentration is measured.

[0029] The test device of this embodiment can obtain data such as the starting condensation temperature of volatile organic matter at low temperature, the relationship between condensation and temperature, and the organic matter concentration at different temperatures. By controlling the opening of the control valve of the vortex tube 5, the temperature of the organic mixed gas output from the cold side outlet of the vortex tube 5 can be changed, and then the concentration of organic matter in the airflow output from the cold side outlet of the rewarming heat exchanger 8 can be changed. By recording the temperature of the organic mixed gas output from the cold side outlet of the vortex tube 5 and the concentration of organic matter in the airflow output from the rewarming heat exchanger 8, data on the organic matter concentration at different temperatures can be obtained. By calculating the difference between the organic matter concentration measured by the first organic matter concentration detection port 101 and the second organic matter concentration detection port 102, the relationship between the condensation rate and the temperature of the organic mixed gas output from the cold side outlet of the vortex tube can also be obtained. The temperature of the organic mixed gas output by the organic saturator 2 can be controlled by the temperature control device 9. By combining the difference in organic concentration measured by the first organic concentration detection port 101 and the second organic concentration detection port 102, the starting condensation temperature of volatile organic matter at low temperature can be determined.

[0030] The embodiment of the present invention can better remove volatile organic compounds through two-stage cooling of dry ice precooling + vortex tube expansion deep cooling, and can obtain simulated exhaust gas with any concentration between 1-2000ppm and any temperature between 0 and -75°C, and can detect the condensation characteristics of volatile organic compounds in the exhaust gas after deep cooling.

[0031] The above description is a further explanation of the present invention in combination with specific implementation methods and drawings. However, the present invention can obviously be implemented in a variety of other methods different from the description, and those skilled in the art can generalize and deduce according to actual usage without violating the content of the present invention. Therefore, the content of the above specific embodiments should not limit the protection scope determined by the present invention.

Claims

1. A volatile organic compound desublimation characteristic detection device, characterized in that: It includes an exhaust gas configuration part, a deep cooling part, a bypass part, a rewarming part, a first organic matter concentration detection port and a second organic matter concentration detection port; The tail gas configuration part includes an air source, an organic saturator and an organic filter, the air source is connected to the organic saturator, the outlet of the organic saturator is connected to the inlet of the organic filter; the organic saturator contains liquid volatile organic matter; the organic saturator includes a shell, the shell has an inner cavity for storing liquid volatile organic matter, and a wire mesh demister is provided on the upper part of the inner cavity; the outlet of the organic saturator is connected to the inner cavity and is located above the wire mesh demister; an air intake line is provided at the bottom of the inner cavity, one end of the air intake line is connected to the air source, the other end of the air intake line is closed, and a plurality of air outlet holes are opened on the side of the air intake line; The cryogenic part includes a precooling heat exchanger, a vortex tube and a capture condensation box; dry ice is arranged in the precooling heat exchanger, the hot side inlet of the precooling heat exchanger is connected to the outlet of the organic filter, the hot side outlet of the precooling heat exchanger is connected to the inlet of the vortex tube, the cold side outlet of the vortex tube is connected to the inlet of the capture condensation box, and a control valve is arranged at the hot side outlet of the vortex tube; the capture condensation box is immersed in a container filled with dry ice as a whole, and heat preservation is achieved by dry ice; The bypass part includes a bypass pipeline; the gas source is connected to the cold side inlet of the precooling heat exchanger through the bypass pipeline; the gas entering the cold side inlet of the precooling heat exchanger is used to perform heat exchange with the organic mixed gas entering the hot side inlet of the precooling heat exchanger; The rewarming part includes a rewarming heat exchanger; the cold side inlet of the rewarming heat exchanger is connected to the outlet of the capture condensation box, and the hot side inlet of the rewarming heat exchanger is used to input heat medium, and the heat medium is used to perform heat exchange with the organic mixed gas entering the cold side inlet of the rewarming heat exchanger; The first organic matter concentration detection port is respectively connected to the outlet of the organic matter filter and the hot side inlet of the pre-cooling heat exchanger, and the second organic matter concentration detection port is connected to the cold side outlet of the rewarming heat exchanger; the first organic matter concentration detection port and the second organic matter concentration detection port are respectively used to connect to an external concentration detection device.

2. A volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: The tail gas configuration part includes a temperature control device, and the temperature control device is used to control the temperature of the mixed gas output from the outlet of the organic matter saturator.

3. A volatile organic compound desublimation characteristic detection device according to claim 2, characterized in that: The temperature control device is a water bath device, an oil bath device or a sand bath device, and the lower part of the organic matter saturator is placed in the water bath device, the oil bath device or the sand bath device.

4. A volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: The diameter of the air outlet hole is 0.2 cm to 0.5 cm.

5. A volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: The precooling heat exchanger is a coil heat exchanger, a shell and tube heat exchanger or a U-tube heat exchanger.

6. A volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: The retemperature heat exchanger is a coil heat exchanger, a shell and tube heat exchanger or a U-tube heat exchanger.

7. A volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: The capture condensation box comprises a box body, the box body is provided with a chamber, a plurality of transverse baffles are arranged in a staggered manner from left to right or from front to back in the chamber, and the plurality of transverse baffles are arranged from top to bottom; A filter screen is also detachably provided in the chamber, and the filter screen is arranged above the plurality of transverse baffles; the inlet of the condensate collection box is arranged below the plurality of transverse baffles, and the outlet of the condensate collection box is arranged above the filter screen.

8. The volatile organic compound desublimation characteristic detection device according to claim 1, characterized in that: Temperature detection devices are respectively provided at the outlet of the organic matter saturator, the inlet of the vortex tube and the cold side outlet of the vortex tube.

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