Improved VOC waste gas non-methane total hydrocarbon and benzene series on-line monitoring system

Abstract

The invention relates to an improved VOC waste gas non-methane total hydrocarbon and benzene series on-line monitoring system, and belongs to the technical field of waste gas monitoring, the improved VOC waste gas non-methane total hydrocarbon and benzene series on-line monitoring system comprises a VOC monitoring subsystem, the VOC monitoring subsystem comprises a sampling probe, a heat tracing pipeline, a pretreatment unit and a VOC analyzer, the heat tracing pipeline comprises a sample gas conveying pipe, a standard gas conveying pipe, a probe blowback conveying pipe, a heat conduction supporting frame and a heat tracing belt, the heat conduction supporting frame is provided with three attaching grooves in the circumferential direction of the heat conduction supporting frame, and the sample gas conveying pipe, the standard gas conveying pipe and the probe blowback conveying pipe are located in the three attaching grooves respectively; the heat tracing band is spirally wound and wrapped outside the sample gas transmission pipe, the standard gas transmission pipe and the probe blowback transmission pipe, and the heat conduction support frame is propped against the heat tracing band. The method has the effects that the heat conduction uniformity of the heat tracing pipeline is improved, and the data accuracy is guaranteed to a certain extent.

Description

Technical Field

[0001] The present application relates to the technical field of waste gas monitoring, and in particular to an improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas. Background Art

[0002] VOC is the English abbreviation of volatile organic compounds, which generally refers to any volatile organic solid or liquid under normal temperature and pressure. In the packaging and printing industry, solvent-based raw and auxiliary materials used in printing, pre-press and post-press processes involve organic solvents such as ink, toluene, xylene, gasoline, and alcohol. In the drying ink process of the gravure printing process, a large amount of VOCs waste gas will be generated. In order to protect the atmospheric environment, it is necessary to monitor the components such as non-methane total hydrocarbons and benzene series in the VOCs waste gas generated in the printing process.

[0003] In related technologies, for example, the Chinese patent document with the publication number CN107132318A discloses a fixed pollution source VOC on-line monitoring system, which includes a VOC monitoring subsystem, a flue gas parameter monitoring subsystem, and a data acquisition and processing subsystem. The VOC monitoring subsystem includes a sampling probe arranged in the chimney, a heating pipeline connected to the sampling probe, a pretreatment unit arranged in the middle of the heating pipeline, and a VOC analyzer connected to the heating pipeline. During measurement, the flue gas passes through the sampling probe, the heating pipeline and the pretreatment unit and is introduced into the VOC analyzer for measurement, and relevant parameters such as methane, non-methane total hydrocarbons, total hydrocarbons, and benzene series in the waste gas can be continuously monitored. Through the flue gas parameter monitoring subsystem, relevant parameters such as flue gas temperature, pressure, and flow rate can be monitored, and the measured data can be effectively managed.

[0004] In view of the above related technologies, at present, the heating pipeline mainly includes a sample gas transmission pipe, a standard gas transmission pipe, and a probe backflush transmission pipe. One end of the sample gas transmission pipe is connected to the sampling probe, and the other end is connected to the VOC analyzer. One end of the standard gas transmission pipe is connected to the standard gas gas source, and the other end is connected to the VOC analyzer. One end of the probe backflush transmission pipe is connected to the gas source, and the other end is connected to the sampling probe. For convenient centralized heating, the middle parts of the sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe usually use the same bundle of heating. Since the middle parts of the sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe are jointly wrapped in the heating tape, it is easy to cause uneven heat conduction on the inner side of the sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe far from the heating tape, affecting the data accuracy. Summary of the Invention

[0005] In order to help improve the heat conduction uniformity of the heating pipeline and ensure the data accuracy to a certain extent, the present application provides an improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas.

[0006] An improved online monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas provided by this application adopts the following technical solutions: An improved online monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas, including a VOC monitoring subsystem. The VOC monitoring subsystem includes a sampling probe, a heating pipeline, a pretreatment unit, and a VOC analyzer. The heating pipeline includes a sample gas transmission pipe, a standard gas transmission pipe, a probe backflush transmission pipe, a heat-conducting support frame, and a heating tape. The heat-conducting support frame has three fitting grooves along its circumferential direction. The sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe are respectively located in the three fitting grooves. The heating tape is spirally wound and wrapped outside the sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe. The heat-conducting support frame is in contact with the heating tape.

[0007] Preferably, the heating pipeline further includes a fitting ring. The fitting ring includes two semi-rings hinged to each other, a fitting head arranged on the semi-ring, and a fixing member arranged on the semi-ring. The fitting head is aligned between adjacent fitting grooves. The fitting head is used to fit the heating tape on the outer walls of the sample gas transmission pipe, the standard gas transmission pipe, and the probe backflush transmission pipe. The fixing member is used to relatively fix or unfold the two semi-rings.

[0008] Preferably, a support bar is slidably arranged on the heat-conducting support frame. There are three support bars, and the three support bars are respectively located between adjacent fitting grooves. An elastic member for supporting the support bar is arranged inside the heat-conducting support frame. The fitting head corresponds to the support bar one by one and is used to abut against the corresponding support bar through the heating tape.

[0009] Preferably, the elastic member includes a spring for supporting the support bar. One end of the spring is arranged on the heat-conducting support frame, and the other end is arranged on the support bar.

[0010] Preferably, when the spring is in a natural state, the distance from the side of the support bar away from the center of the heat-conducting support frame to the center of the heat-conducting support frame is equal to the distance from the side of the sample gas transmission pipe away from the center of the heat-conducting support frame to the center of the heat-conducting support frame.

[0011] Preferably, the fixing member includes a screw. One ends of the two semi-rings away from the hinged part are detachably fixed by the screw.

[0012] Preferably, the heating pipeline further includes a heat-insulating layer and a protective layer. The heat-insulating layer is wrapped outside the fitting ring, and the protective layer is wrapped outside the heat-insulating layer.

[0013] Preferably, the heat-insulating layer is a fiberglass layer, and the protective layer is a heat-resistant rubber layer.

[0014] Preferably, the heat-conducting support frame is provided with a clamping group, and the clamping groups correspond to the fitting grooves one by one. Each clamping group includes two clamping pieces arranged on the heat-conducting support frame. The two clamping pieces are located on opposite sides of the fitting groove, and the two clamping pieces are used to fit with the corresponding sample gas transmission pipe, standard gas transmission pipe or probe back-blow transmission pipe.

[0015] Preferably, the heat-conducting support frame is a copper alloy support frame.

[0016] In summary, the present application includes the following beneficial technical effects: When the heating tape is heated, since the heat-conducting support frame abuts against the heating tape, heat can be transferred to the inner sides of the sample gas transmission pipe, the standard gas transmission pipe and the probe back-blow transmission pipe away from the heating tape, which helps to improve the heat conduction uniformity of the sample gas transmission pipe, the standard gas transmission pipe and the probe back-blow transmission pipe, and ensures the data accuracy to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of an embodiment of the present application.

[0018] Figure 2 is Figure 1 the cross-sectional view taken along line A-A in

[0019] Figure 3 is an exploded view of the partial structure of an embodiment of the present application.

[0020] Description of the reference numerals: 1, sampling probe; 2, heat tracing pipeline; 21, sample gas transmission pipe; 22, standard gas transmission pipe; 23, probe back-blow transmission pipe; 24, heat-conducting support frame; 25, heating tape; 26, fitting ring; 261, half ring; 262, fitting head; 27, heat preservation layer; 28, protective layer; 3, pretreatment unit; 4, VOC analyzer; 5, fitting groove; 6, support bar; 7, spring; 8, clamping group; 81, clamping piece; 9, guiding telescopic rod. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following Figures 1-3 is a further detailed description of the present application.

[0022] An embodiment of the present application discloses an improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas. Referring to Figure 1 , the improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas includes a VOC monitoring subsystem. The VOC monitoring subsystem includes a sampling probe 1, a heat tracing pipeline 2, a pretreatment unit 3 and a VOC analyzer 4. Among them, the sampling probe 1, the pretreatment unit 3 and the VOC analyzer 4 are all prior arts, and their structures and principles will not be elaborated herein.

[0023] Referring toFigure 1 and Figure 2 Specifically, the tracing pipeline 2 includes a sample gas transmission pipe 21, a standard gas transmission pipe 22, a probe backflush transmission pipe 23, a heat conduction support frame 24, and a tracing tape 25. One end of the sample gas transmission pipe 21 is connected to the sampling probe 1, and the other end is connected to the VOC analyzer 4. The pretreatment unit 3 is arranged at one end of the sample gas transmission pipe 21 close to the VOC analyzer 4. The flue gas passes through the sampling probe 1, the sample gas transmission pipe 21, and the pretreatment unit 3 and enters the VOC analyzer 4 for measurement, so that relevant parameters such as methane, non-methane total hydrocarbons, total hydrocarbons, and benzene series in the waste gas can be continuously monitored.

[0024] Refer to Figure 1 and Figure 2 One end of the standard gas transmission pipe 22 is connected to the standard gas source, and the other end is connected to the VOC analyzer 4 to realize the full-course calibration of the standard gas; one end of the probe backflush transmission pipe 23 is connected to the gas source, and the other end is connected to the sampling probe 1 to realize the backflush cleaning of the sampling probe 1. The sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 are all made of 316L stainless steel, which can reduce gas adsorption.

[0025] Refer to Figure 1 and Figure 2 Both ends of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 are respectively traced by the electric tracing tape, and the middle transmission position is traced by the same bundle; the heat conduction support frame 24 is a copper alloy support frame, which can transfer heat efficiently. The heat conduction support frame 24 is located at the same bundle tracing position of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23.

[0026] Refer to Figure 2 Specifically, the heat conduction support frame 24 has three circular arc-shaped fitting grooves 5 along its circumferential direction. The sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 are respectively located in the three fitting grooves 5. The tracing tape 25 is specifically an electric tracing tape with constant power. The tracing tape 25 is spirally wound and wrapped outside the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23. The heat conduction support frame 24 is in contact with the tracing tape 25.

[0027] When the tracing tape 25 is heated, the tracing tape 25 generates heat to jointly heat the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23. Since the heat conduction support frame 24 is in contact with the tracing tape 25, the heat can be transferred to the inner sides of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 far from the tracing tape 25, which helps to improve the heat conduction uniformity of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 and ensures the data accuracy to a certain extent.

[0028] Refer toFigure 2 and Figure 3 For the convenience of installing the sample gas transfer pipe 21, the standard gas transfer pipe 22, and the probe backflush transfer pipe 23, the heat conduction support frame 24 is provided with a clamping group 8. The clamping group 8 corresponds to the fitting groove 5 one by one. Each clamping group 8 includes two clamping pieces 81 integrally formed on the heat conduction support frame 24. The two clamping pieces 81 are located on the opposite sides of the corresponding fitting groove 5. The clamping piece 81 is arc-shaped, and the two clamping pieces 81 are used to fit with the corresponding sample gas transfer pipe 21, standard gas transfer pipe 22, or probe backflush transfer pipe 23. Specifically, the clamping piece 81 is made of the same material as the heat conduction support frame 24, has good heat conduction performance and certain elasticity, and is convenient for limiting the transfer pipe. The setting of the clamping piece 81 can respectively snap the sample gas transfer pipe 21, the standard gas transfer pipe 22, and the probe backflush transfer pipe 23 into the corresponding fitting groove 5 to relatively fix their positions, thereby facilitating the winding of the heating tape 25.

[0029] Refer to Figure 2 and Figure 3 To further improve the heat conduction effect, the heating pipeline 2 further includes a fitting ring 26. Specifically, the fitting ring 26 includes a half-ring 261, a fitting head 262, and a fixing member. There are two half-rings 261. One end of the two half-rings 261 is hinged to each other. The hinge axis of the two half-rings 261 is parallel to the length direction of the heat conduction support frame 24, so that the two half-rings 261 can be enclosed into a ring shape for wrapping around the heating tape 25. The fitting head 262 is integrally formed on the inner side of the half-ring 261. The fitting heads 262 on the two half-rings 261 correspond to the gaps between the adjacent fitting grooves 5 one by one, and the fitting heads 262 are aligned with the gaps between the adjacent fitting grooves 5. The fitting heads 262 are used to fit the heating tape 25 on the outer walls of the sample gas transfer pipe 21, the standard gas transfer pipe 22, and the probe backflush transfer pipe 23. The fixing member is arranged on the half-ring 261 and is used to relatively fix or unfold the two half-rings 261.

[0030] Refer to Figure 2 and Figure 3 To facilitate the relative fixing or unfolding of the two half-rings 261, the fixing member includes a screw, and one end of the two half-rings 261 away from the hinge is detachably fixed by the screw.

[0031] After the heating tape 25 is wound, put the two half-rings 261 on the outside of the heating tape 25, align the fitting heads 262 with the gaps between the corresponding adjacent fitting grooves 5, then enclose the two half-rings 261, and fix the ends of the two half-rings 261 away from the hinge by screws. The heating tape 25 is abutted by the fitting heads 262 and fitted between the adjacent two transfer pipes, thereby expanding the fitting area between the heating tape 25 and the sample gas transfer pipe 21, the standard gas transfer pipe 22, and the probe backflush transfer pipe 23, and further helping to improve the heat conduction effect.

[0032] Reference Figure 2 and Figure 3 On the heat-conducting support frame 24, a support bar 6 is slidably arranged. The sliding direction of the support bar 6 is perpendicular to the length direction of the heat-conducting support frame 24. The support bar 6 is made of the same material as the heat-conducting support frame 24 and also has good heat-conducting performance. There are three support bars 6, and the three support bars 6 are respectively located between adjacent fitting grooves 5, that is, the support bar 6 is located between adjacent clamping groups 8. To facilitate the guiding of the sliding of the support bar 6, a plurality of guiding telescopic rods 9 are fixed between each support bar 6 and the heat-conducting support frame 24. The guiding telescopic rods 9 are arranged on the heat-conducting support frame 24, so that the support bar 6 can slide to abut against the heat-conducting support frame 24. An elastic member for supporting the support bar 6 is arranged in the heat-conducting support frame 24. The fitting heads 262 correspond to the support bars 6 one by one and are used to abut against the corresponding support bars 6 with the spacer heating tape 25 in between.

[0033] Reference Figure 2 and Figure 3 To facilitate the support of the support bar 6, the elastic member includes a spring 7. The spring 7 corresponds to the guiding telescopic rod 9 one by one. The spring 7 is movably sleeved on the corresponding guiding telescopic rod 9. One end of the spring 7 is fixed on the inner wall of the heat-conducting support frame 24, and the other end is fixed on the side where the guiding telescopic rod 9 is connected to the support bar 6. When the spring 7 is in the natural state, the distance from the side of the support bar 6 away from the center of the heat-conducting support frame 24 to the center of the heat-conducting support frame 24 is equal to the distance from the side of the sample gas transmission pipe 21 away from the center of the heat-conducting support frame 24 to the center of the heat-conducting support frame 24, so as to be able to support the heating tape 25. To reduce the interference between structures, the guiding telescopic rods 9 corresponding to the three support bars 6 are arranged in a staggered manner, so that the plurality of guiding telescopic rods 9 will not interfere with each other inside the heat-conducting support frame 24.

[0034] Due to the limited elasticity and toughness of the heating tape 25, when the heating tape 25 is wound, through the support of the three support bars 6, the heating tape 25 can be supported and expanded to a certain extent. Thus, when the fitting ring 26 is installed, it is convenient for the fitting head 262 to abut against the support bar 6 and move towards the direction close to the heat-conducting support frame 24, so that the heating tape 25 can be better attached between adjacent transmission pipes, expanding the attachment area and preventing the transmission pipes from being damaged due to the tight extrusion of the heating tape 25.

[0035] Reference Figure 2 To facilitate the protection of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23, the heat tracing pipeline 2 further includes a heat insulation layer 27 and a protective layer 28. The heat insulation layer 27 is wrapped outside the fitting ring 26, specifically a fiberglass layer; the protective layer 28 is wrapped outside the heat insulation layer 27, specifically a heat-resistant rubber layer, which helps to ensure that the pipeline is not easily damaged and improve the transmission stability. In other embodiments, the heat insulation layer 27 can also be a ceramic fiber layer, and the protective layer 28 can also be a polyethylene layer, a polyvinyl chloride layer, etc.

[0036] The implementation principle of the embodiment of this application is as follows: After the tracing pipeline 2 is installed, the fitting ring 26 is wrapped around the tracing tape 25, and the fitting head 262 of the fitting ring 26 abuts against the support bar 6, so that the support bar 6 abuts against the heat conduction support frame 24. The fitting head 262 closely fits the tracing tape 25 between adjacent transmission pipes, expanding the contact area between the tracing tape 25 and the outer walls of the three transmission pipes. The heat conduction support frame 24 abuts against the tracing tape 25 through the support bar 6, and good heat conduction can be achieved.

[0037] When the tracing tape 25 is heated, the tracing tape 25 generates heat to jointly heat the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23. Since the heat conduction support frame 24 abuts against the tracing tape 25 through the support bar 6, the heat can be transferred to the inner sides of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23 that are far away from the tracing tape 25, which helps to improve the heat conduction uniformity of the sample gas transmission pipe 21, the standard gas transmission pipe 22, and the probe backflush transmission pipe 23, and ensures the data accuracy to a certain extent.

[0038] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this application.

Claims

1. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas, including a VOC monitoring subsystem, the VOC monitoring subsystem includes a sampling probe (1), a heating pipeline (2), a pretreatment unit (3) and a VOC analyzer (4), characterized in that, The traced pipeline (2) includes a sample gas transmission pipe (21), a standard gas transmission pipe (22), a probe backflush transmission pipe (23), a heat-conducting support frame (24), and a heating tape (25). The heat-conducting support frame (24) has three fitting grooves (5) along its circumferential direction. The sample gas transmission pipe (21), the standard gas transmission pipe (22), and the probe backflush transmission pipe (23) are respectively located in the three fitting grooves (5). The heating tape (25) is spirally wound and wrapped outside the sample gas transmission pipe (21), the standard gas transmission pipe (22), and the probe backflush transmission pipe (23). The heat-conducting support frame (24) is in contact with the heating tape (25).

2. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 1, characterized in that: The traced pipeline (2) further includes a fitting ring (26). The fitting ring (26) includes two half rings (261) hinged to each other, a fitting head (262) provided on the half ring (261), and a fixing member provided on the half ring (261). The fitting head (262) is aligned between adjacent fitting grooves (5). The fitting head (262) is used to fit the heating tape (25) on the outer walls of the sample gas transmission pipe (21), the standard gas transmission pipe (22), and the probe backflush transmission pipe (23). The fixing member is used to relatively fix or unfold the two half rings (261).

3. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 2, characterized in that: A support bar (6) is slidably arranged on the heat-conducting support frame (24). There are three support bars (6), and the three support bars (6) are respectively located between adjacent fitting grooves (5). An elastic member for supporting the support bar (6) is arranged in the heat-conducting support frame (24). The fitting head (262) corresponds to the support bar (6) one by one and is used to abut against the corresponding support bar (6) with the heating tape (25) in between.

4. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 3, characterized in that: The elastic member includes a spring (7) for supporting the support bar (6). One end of the spring (7) is arranged on the heat-conducting support frame (24), and the other end is arranged on the support bar (6).

5. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 4, characterized in that: When the spring (7) is in a natural state, the distance from the side of the support bar (6) away from the center of the heat-conducting support frame (24) to the center of the heat-conducting support frame (24) is equal to the distance from the side of the sample gas transmission pipe (21) away from the center of the heat-conducting support frame (24) to the center of the heat-conducting support frame (24).

6. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 2, characterized in that: The fixing member includes a screw. One ends of the two half rings (261) away from the hinge are detachably fixed by the screw.

7. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 2, characterized in that: The traced pipeline (2) further includes a heat-insulating layer (27) and a protective layer (28). The heat-insulating layer (27) is wrapped outside the fitting ring (26), and the protective layer (28) is wrapped outside the heat-insulating layer (27).

8. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 7, characterized in that: The heat-insulating layer (27) is a fiberglass layer, and the protective layer (28) is a heat-resistant rubber layer.

9. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to claim 1, characterized in that: The heat-conducting support frame (24) is provided with a clamping group (8), and the clamping group (8) corresponds to the fitting groove (5) one by one. Each clamping group (8) includes two clamping pieces (81) arranged on the heat-conducting support frame (24). The two clamping pieces (81) are located on opposite sides of the fitting groove (5), and the two clamping pieces (81) are used to fit with the corresponding sample gas transmission pipe (21), standard gas transmission pipe (22) or probe backflush transmission pipe (23).

10. An improved on-line monitoring system for non-methane total hydrocarbons and benzene series in VOC waste gas according to any one of claims 1-9, characterized in that: The heat-conducting support frame (24) is a copper alloy support frame.

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