Non-methane total hydrocarbon measuring device applying catalytic oxidation-non-dispersive infrared method

Abstract

The utility model belongs to the technical field of gas detection devices, and provides a non-methane total hydrocarbon measuring device applying a catalytic oxidation-non-dispersive infrared method, which comprises a catalytic oxidation mechanism and a detection mechanism, the catalytic oxidation mechanism comprises an injection pump, a first control valve, a second control valve and a catalytic furnace, the first control valve is communicated with an inlet and an outlet of the injection pump, and the second control valve is communicated with an inlet and an outlet of the detection mechanism. The second control valve is communicated with the first control valve and the catalytic furnace, the detection mechanism comprises an infrared optical platform and a methane detection module, a gas inlet of the infrared optical platform is communicated with a gas outlet of the catalytic furnace and the second control valve, and a gas outlet of the infrared optical platform is communicated with a gas inlet of the methane detection module; the first control valve is used for controlling the inlet and outlet of the injection pump to be communicated with the outside or the second control valve, and the second control valve is used for controlling whether the catalytic furnace is connected between the inlet and outlet of the injection pump and the air inlet of the infrared optical platform. The measuring device has the advantages of being simple and compact in structure, high in sensitivity and good in repeatability and stability.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection devices, in particular to a non-methane total hydrocarbon measurement device using a catalytic oxidation-non-dispersive infrared method. Background Art

[0002] The measurement technologies currently used in the online monitoring of volatile organic compounds (VOCs) emissions on the market mainly include: gas chromatography-hydrogen flame ionization detector (GC-FID), catalytic oxidation-hydrogen flame ionization detector (catalytic oxidation-FID), photoionization detector (PID), and catalytic oxidation-non-dispersive infrared. The advantage of FID detection is that it responds to almost all volatile organic compounds, but the disadvantage is that the response is greatly affected by the injection flow rate and has poor stability; the equipment is expensive; the detection process consumes reagents, hydrogen, and auxiliary facilities such as carrier gas, and the operation and maintenance costs are high. The advantage of PID detection is that the equipment is cheap, but the disadvantage is that the responsiveness is relatively poor and the response of different substances varies greatly.

[0003] The principle of the catalytic oxidation-non-dispersive infrared method is: control the switching valve to allow VOC to directly enter the carbon dioxide infrared detector to measure the background carbon dioxide concentration (C1); switch to the catalytic oxidation device to catalyze the carbon atoms of non-methane hydrocarbons in the VOC into carbon dioxide, while methane is not catalyzed, and then enter the carbon dioxide infrared detector to measure the carbon dioxide concentration after oxidation (C2); according to the principle of carbon conservation, the difference (C2-C1) between the carbon dioxide concentration after combustion (C2) and the background carbon dioxide concentration (C1) is equal to the concentration of non-methane hydrocarbons in the VOC, and the carbon concentration is used to characterize the VOC content.

[0004] The advantages of the catalytic-non-dispersive infrared method are:

[0005] (1) It responds to most volatile organic compounds, and its responsiveness is close to that of FID and significantly better than that of PID;

[0006] (2) Infrared carbon dioxide detection technology is mature, with simple structure, easy operation and low operation and maintenance costs;

[0007] (3) The detection process does not consume any reagents, hydrogen, or auxiliary facilities such as carrier gas. Relatively speaking, the equipment has relatively low requirements for site space and environment.

[0008] From the perspective of finding an economically and technically feasible VOCs online monitoring technology, the catalytic oxidation-non-dispersive infrared method has gradually been recognized by the market. At present, the catalytic oxidation-non-dispersive infrared method instruments have been operated in the production sites of industries including automobile coating industry, aluminum profile industry, non-woven fabric industry, shoemaking industry, furniture industry, printing industry, chemical pharmaceutical industry, stainless steel processing industry, etc., with good results.

[0009] However, this method may also cause inaccurate measurements under certain circumstances. For example, if the treatment process of the VOCs treatment device adopts a combustion process, such as the RTO combustion method, a large amount of VOCs will be burned, which will generate a large amount of carbon dioxide (i.e., background carbon dioxide C1) and add it to the sample gas. When these sample gases are discharged, the volume concentration of carbon dioxide fluctuates greatly. The sampling concentration can exceed 10,000 μmol / mol (i.e., background carbon dioxide concentration C1) a few seconds ago, and the sampling may drop to no more than 400 μmol / mol a few seconds later. After the VOC in the sample gas is catalytically oxidized, the increase in carbon dioxide concentration may be only about 50 μmol / mol, so the carbon dioxide concentration (C2) after catalytic oxidation is only about 450 μmol / mol. Then the value obtained according to C2-C1 becomes a negative number, which is an inaccurate measurement value.

[0010] In order to solve the problem of excessive carbon dioxide in the sample gas interfering with the infrared detection sensor's measurement of residual VOCs, the products on the market at this stage generally use a quantitative ring (actually a certain length of air pipe rolled into a spiral ring with a diameter of about 1 meter) in the sampling pipeline to increase the mixing time of the sample gas and eliminate the influence of carbon dioxide as the background gas. However, the sample gas mixing of this method is not sufficient, and it is only limited to the use in the production or treatment process without combustion process, and the exhaust gas emission volume of carbon dioxide background volume concentration does not exceed several thousand μmol / mol. The utility model is developed to improve the above products on the market.

[0011] The technical problem to be solved by the utility model is: how to provide a non-methane total hydrocarbon measuring device using a catalytic oxidation-non-dispersive infrared method with a simple and compact structure and good stability. Utility Model Content

[0012] In order to overcome the deficiencies of the prior art, the purpose of the utility model is to provide a non-methane total hydrocarbon measurement device using a catalytic oxidation-non-dispersive infrared method, which has the characteristics of simple and compact structure, high sensitivity, good repeatability and stability.

[0013] The technical solution adopted by the utility model is: a non-methane total hydrocarbon measuring device using a catalytic oxidation-non-dispersive infrared method, comprising a catalytic oxidation mechanism and a detection mechanism, the catalytic oxidation mechanism comprising an injection pump, a first control valve, a second control valve and a catalytic furnace, the first control valve is connected to the inlet and outlet of the injection pump, the second control valve is connected to the first control valve and the catalytic furnace, the detection mechanism comprises an infrared optical platform and a methane detection module, the air inlet of the infrared optical platform is connected to the air outlet of the catalytic furnace and the second control valve, the air outlet of the infrared optical platform is connected to the air inlet of the methane detection module, the first control valve is used to control the inlet and outlet of the injection pump to be connected to the outside or the second control valve, and the second control valve is used to control whether the inlet and outlet of the injection pump and the air inlet of the infrared optical platform are connected to the catalytic furnace.

[0014] The non-methane total hydrocarbon measurement device using the catalytic oxidation-non-dispersive infrared method of the present application has the advantages of simple and compact structure, high detection sensitivity, good repeatability and stability. The sampling gas can be fully and evenly mixed by using a syringe pump, which solves the problem of large measurement errors caused by large fluctuations in carbon dioxide emissions. It can also achieve quantitative and constant-speed sampling, realize controllable operation of the sampling process, and control the volume of the gas sucked by the syringe pump according to actual needs to obtain samples of different volumes. There is no need to equip sampling quantitative rings of different capacities, and the versatility is better. It can realize online analysis and detection of samples of different concentrations at the treatment outlet, while reducing the volume of the instrument, without having to make a large quantitative ring, making the structure more compact.

[0015] During measurement, the first control valve connects the inlet and outlet of the injection pump to the outside and disconnects the inlet and outlet of the injection pump from the second control valve. At this time, the injection pump draws the sample gas. After the sample gas is fully mixed in the injection pump, the first control valve controls the inlet and outlet of the injection pump to be disconnected from the outside and connect the inlet and outlet of the injection pump to the second control valve. The second control valve controls the sample gas to directly enter the infrared optical platform and the methane detection module without passing through the catalytic furnace (the concentration of methane is not measured at this time), and measures the concentration of carbon dioxide originally contained in the sample gas, that is, the background carbon dioxide concentration (C1); then the second control valve controls the sample gas to first pass through the catalytic furnace for catalytic oxidation reaction, catalyzes the carbon atoms of non-methane total hydrocarbons in the sample gas into carbon dioxide, and then enters the infrared optical platform to measure the concentration of carbon dioxide after oxidation (C2). Because methane cannot be catalyzed, the concentration of methane can be accurately measured by the methane detection module afterwards. According to the principle of carbon conservation, the difference (C2-C1) between the concentration of carbon dioxide after catalysis (C2) and the concentration of background carbon dioxide (C1) is equal to the concentration of non-methane total hydrocarbons in the sample gas. The carbon concentration is used to characterize the VOC content, and the concentration of total hydrocarbons is the sum of the concentration of non-methane total hydrocarbons and the concentration of methane.

[0016] In some embodiments, the first control valve and the second control valve are both three-way solenoid valves, the common end of the first control valve is connected to the inlet and outlet of the injection pump, the normally closed end of the first control valve is connected to the outside, the normally open end of the first control valve is connected to the common end of the second control valve, the normally closed end of the second control valve is connected to the air inlet of the infrared optical platform, and the normally open end of the second control valve is connected to the air inlet of the catalytic furnace.

[0017] By adopting the above technical solution, when the injection pump is to extract a fixed volume of sample gas, the first control valve will be powered on and switched, that is, its common end is connected to the normally closed end, and the common end is closed to the normally open end. The second control valve is not powered at this time, and its common end is connected to the normally open end. The injection pump starts to suck the sample gas from the normally closed end of the first control valve into the injection pump, and the sample gas is quickly mixed inside the injection pump. Because the common end and the normally open end of the first control valve are closed at this time, the inhaled sample gas can only flow into the injection pump from the normally closed end of the first control valve, and cannot be the air sucked in from the outlet of the methane detection module. After inhaling a certain amount of sample gas, the injection pump will stay for a certain period of time to allow the sample gas to be more fully mixed and the gas state to be more stable;

[0018] When the injection pump is exhausting, the first control valve is first switched to a state where the common end is connected to the normally open end and the common end is closed to the normally closed end, and the second control valve is switched to a state where the common end is connected to the normally closed end and the common end is closed to the normally open end. The injection pump then slowly discharges the sample gas outward, slowly passing through the first control valve, the second control valve, the infrared optical platform and the methane detection module in turn, and then discharged into the atmosphere to measure the background carbon dioxide concentration; when the injection pump discharges half of the fully mixed sample gas extracted, the second control valve is switched to a state where the common end is connected to the normally open end and the common end is not connected to the normally closed end. At this time, the sample gas will directly pass through the catalytic furnace for catalytic oxidation. Due to the low flow rate, the reaction between the sample gas and the catalyst in the catalytic furnace is more complete, and the catalytic efficiency is higher. Then it flows into the infrared optical platform and the methane detection module in turn to measure the oxidized carbon dioxide concentration and methane concentration, and then discharged into the atmosphere.

[0019] In some embodiments, the first control valve includes a first two-way solenoid valve and a second two-way solenoid valve, and the second control valve includes a third two-way solenoid valve and a fourth two-way solenoid valve;

[0020] The air inlet of the first two-way solenoid valve is connected to the outside, and the air outlet is connected to the inlet and outlet of the injection pump, the air inlet of the second two-way solenoid valve is connected to the inlet and outlet of the injection pump, and the air outlet is connected to the air inlet of the third two-way solenoid valve and the air inlet of the fourth two-way solenoid valve, the air outlet of the third two-way solenoid valve is connected to the air inlet of the catalytic furnace, and the air outlet of the fourth two-way solenoid valve is connected to the air inlet of the infrared optical platform.

[0021] By adopting the above technical solution, when inhaling, the first two-way solenoid valve is connected, and the second two-way solenoid valve, the third two-way solenoid valve and the fourth two-way solenoid valve remain closed; when measuring the background carbon dioxide concentration, the first two-way solenoid valve and the third two-way solenoid valve are closed, and the second two-way solenoid valve and the fourth two-way solenoid valve are connected; when measuring the carbon dioxide concentration after oxidation, the first two-way solenoid valve and the fourth two-way solenoid valve are closed, and the second two-way solenoid valve and the third two-way solenoid valve are connected.

[0022] In some embodiments, a heating box is further included, wherein the injection pump, the first control valve, the second control valve and the catalytic furnace are built into the heating box, and the infrared optical platform and the methane detection module are installed on the outer wall of the heating box.

[0023] By adopting the above technical solution, the catalytic oxidation mechanism is arranged in the heating box to ensure that the sample gas entering the heating box does not condense and release condensed water during the whole process, thereby avoiding moisture interference with the measurement of the infrared optical platform and ensuring accuracy.

[0024] In some embodiments, the operating temperature range of the heating box is 100-140 degrees Celsius.

[0025] By adopting the above technical solution, the sample gas within this temperature range will not condense during the whole process, thus ensuring the accuracy of the measurement results.

[0026] In some embodiments, the first control valve and the second control valve are high temperature resistant solenoid valves.

[0027] By adopting the above technical solution, the high temperature resistant solenoid valve can work normally at high temperature, ensuring that the measuring device can work normally and extending the service life.

[0028] In some embodiments, the injection pump includes a cylinder, a piston, a push rod and a power component. An inlet and an outlet are provided at one end of the cylinder, the piston is built into the cylinder, the push rod extends into the cylinder from the end away from the inlet and an outlet and is connected to the piston, and the power component is used to drive the push rod to perform reciprocating linear motion along the axial direction of the cylinder.

[0029] By adopting the above technical solution, quantitative and constant-speed sampling can be achieved, and the sampling process can be controlled.

[0030] In some embodiments, the piston is made of polytetrafluoroethylene.

[0031] By adopting the above technical solution, the polytetrafluoroethylene piston is corrosion-resistant and leak-proof, and no lubricating grease needs to be added, thereby preventing the lubricating grease from releasing VOCs and affecting the measurement results.

[0032] In some embodiments, the power component is a motor, a lead screw is connected to the output end of the motor, and a nut that cooperates with the lead screw is connected to the push rod.

[0033] By adopting the above technical solution, the reciprocating motion of the piston in the cylinder is made more stable and reliable.

[0034] In some embodiments, a controller is further included, and the controller is signal-connected to the injection pump, the first control valve, the second control valve, the catalytic furnace, the infrared optical platform, and the methane detection module.

[0035] By adopting the above technical solution, automatic control of the detection process can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of a non-methane total hydrocarbon measurement device using a catalytic oxidation-non-dispersive infrared method according to a first embodiment of the utility model;

[0037] Figure 2 for Figure 1 The structural schematic diagram of the injection pump shown;

[0038] Figure 3 It is a schematic structural diagram of a non-methane total hydrocarbon measuring device using a catalytic oxidation-non-dispersive infrared method according to a second embodiment of the present invention.

[0039] In the figure: 100, non-methane total hydrocarbon measurement device using catalytic oxidation-non-dispersive infrared method; 10, catalytic oxidation mechanism; 11, injection pump; 111, gas cylinder; 112, piston; 113, push rod; 114, power part; 115, screw; 116, nut; 12, first control valve; 121, first two-way solenoid valve; 122, second two-way solenoid valve; 13, second control valve; 131, third two-way solenoid valve; 132, fourth two-way solenoid valve; 14, catalytic furnace; 20, detection mechanism; 21, infrared optical platform; 22, methane detection module; 30, heating box; 40, air inlet nozzle; 50, air outlet nozzle. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0041] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. When the number of an element is referred to as "plurality", it may be any number of two or more. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0043] First embodiment:

[0044] See also Figure 1 and Figure 2 , which is a first embodiment of the utility model, a non-methane total hydrocarbon measurement device 100 using a catalytic oxidation-non-dispersive infrared method, includes a catalytic oxidation mechanism 10 and a detection mechanism 20. The catalytic oxidation mechanism 10 includes an injection pump 11, a first control valve 12, a second control valve 13 and a catalytic furnace 14. The first control valve 12 is connected to the inlet and outlet of the injection pump 11, and the second control valve 13 is connected to the first control valve 12 and the catalytic furnace 14. The detection mechanism 20 includes an infrared optical platform 21 and a methane detection module 22. The air inlet of the infrared optical platform 21 is connected to the air outlet of the catalytic furnace 14 and the second control valve 13. The air outlet of the infrared optical platform 21 is connected to the air inlet of the methane detection module 22. The first control valve 12 is used to control the inlet and outlet of the injection pump 11 to be connected to the outside or the second control valve 13. The second control valve 13 is used to control whether the catalytic furnace 14 is connected between the inlet and outlet of the injection pump 11 and the air inlet of the infrared optical platform 21. It should be noted that the first control valve 12 controls the inlet and outlet of the injection pump 11 to be connected to the outside, which means that the inlet and outlet of the injection pump 11 can be directly connected to the outside through the first control valve 12 .

[0045] The non-methane total hydrocarbon measurement device 100 of the present application using the catalytic oxidation-non-dispersive infrared method has the advantages of simple and compact structure, high detection sensitivity, good repeatability and stability. The injection pump 11 can be used to fully and evenly mix the sampled gas, solving the problem of large measurement errors caused by large fluctuations in carbon dioxide emissions. It can also achieve quantitative and constant-speed sampling, realize controllable operation of the sampling process, and control the volume of the gas sucked by the injection pump 11 according to actual needs to obtain samples of different volumes. There is no need to equip sampling quantitative rings of different capacities, and the versatility is better. It can realize online analysis and detection of samples of different concentrations at the treatment outlet, while reducing the volume of the instrument, without having to make a large quantitative ring, making the structure more compact.

[0046] In this embodiment, the first control valve 12 and the second control valve 13 are both three-way solenoid valves, the common end of the first control valve 12 is connected to the inlet and outlet of the injection pump 11, the normally closed end of the first control valve 12 is connected to the outside, the normally open end of the first control valve 12 is connected to the common end of the second control valve 13, the normally closed end of the second control valve 13 is connected to the air inlet of the infrared optical platform 21, and the normally open end of the second control valve 13 is connected to the air inlet of the catalytic furnace 14. When the injection pump 11 wants to extract a fixed volume of sample gas, the first control valve 12 will be powered on and switched, that is, its common end is connected to the normally closed end, and the common end is closed to the normally open end. The second control valve 13 is not powered on at this time, and its common end is connected to the normally open end. The injection pump 11 starts to suck the sample gas from the normally closed end of the first control valve 12 into the injection pump 11, and the sample gas is quickly mixed inside the injection pump 11. Because the common end and the normally open end of the first control valve 12 are closed at this time, the inhaled sample gas can only flow into the injection pump 11 from the normally closed end of the first control valve 12, and cannot be the air sucked in from the outlet of the methane detection module 22. After a certain amount of sample gas is inhaled, the injection pump 11 will stay for a certain period of time to make the sample gas more fully mixed and the gas state more stable; when the injection pump 11 is exhausted, the first control valve 12 is first switched to a state where the common end is connected to the normally open end and the common end is closed to the normally closed end, and the second control valve 13 is switched to a state where the common end is connected to the normally closed end and the common end is closed to the normally open end, and the injection pump 11 then slowly discharges the sample gas outward, slowly passing through the first control valve 12, the second control valve 13, the infrared optical platform 21 and the methane detection module 22 in sequence, and then discharged to In the atmosphere, the background carbon dioxide concentration is measured; when the injection pump 11 discharges half of the fully mixed sample gas extracted, the second control valve 13 is switched to a state in which the common end is connected to the normally open end, and the common end is not connected to the normally closed end. At this time, the sample gas will directly pass through the catalytic furnace 14 to be catalytically oxidized. Due to the low flow rate, the reaction between the sample gas and the catalyst in the catalytic furnace 14 is more complete, and the catalytic efficiency is higher. Then, the sample gas flows into the infrared optical platform 21 and the methane detection module 22 in turn to measure the oxidized carbon dioxide concentration and methane concentration, and then is discharged into the atmosphere.

[0047] Optionally, in other embodiments, the first control valve 12 and the second control valve 13 may also be configured as other manual, pneumatic, or hydraulic three-way valves that can achieve equivalent functions.

[0048] Preferably, the measuring device further comprises a heating box 30, wherein the injection pump 11, the first control valve 12, the second control valve 13 and the catalytic furnace 14 are built into the heating box 30, and the infrared optical platform 21 and the methane detection module 22 are installed on the outer wall of the heating box 30. The catalytic oxidation mechanism 10 is arranged in the heating box 30 to ensure that the sample gas entering the heating box 30 does not condense during the whole process, and does not release condensed water, so as to avoid moisture interfering with the measurement of the infrared optical platform 21 and ensure accuracy. Optionally, the operating temperature range of the heating box 30 is 100-140 degrees Celsius, and the sample gas in this temperature range does not condense during the whole process, so as to ensure the accuracy of the measurement result.

[0049] Correspondingly, the first control valve 12 and the second control valve 13 are high temperature resistant solenoid valves. High temperature resistant solenoid valves can work normally at high temperatures, ensuring that the measuring device can work normally and extending the service life.

[0050] Optionally, the measuring device also includes an air inlet nozzle 40 and an air outlet nozzle 50. The air inlet nozzle 40 is installed on the side wall of the heating box 30, and the air inlet nozzle 40 is connected to the normally closed end of the first control valve 12, and the air outlet nozzle 50 is connected to the air outlet of the methane detection module 22.

[0051] like Figure 2 As shown, in this embodiment, the syringe pump 11 includes a cylinder 111, a piston 112, a push rod 113 and a power member 114. An inlet and an outlet are provided at one end of the cylinder 111. The piston 112 is built into the cylinder 111. The push rod 113 extends from the end away from the inlet and an outlet into the cylinder 111 and is connected to the piston 112. The power member 114 is used to drive the push rod 113 to perform reciprocating linear motion along the axial direction of the cylinder 111. With the above structure, quantitative and constant speed sampling can be achieved, and the sampling process can be controlled.

[0052] Preferably, the piston 112 is made of polytetrafluoroethylene. The polytetrafluoroethylene piston 112 is corrosion-resistant and leak-proof, and does not require the addition of lubricating grease, thereby preventing the lubricating grease from releasing VOCs and affecting the measurement results.

[0053] In this embodiment, the power member 114 is a motor, the output end of the motor is connected to a lead screw 115, and the push rod 113 is connected to a nut 116 that is in transmission cooperation with the lead screw 115. The reciprocating motion of the piston 112 in the cylinder 111 is made more stable and reliable. Optionally, the motor is a servo motor or a stepper motor. Further, in order to facilitate the control of the air intake and exhaust volume of the injection pump 11, the displacement of the piston 112 can be controlled by setting a travel switch.

[0054] Of course, in other embodiments, a gas cylinder or an oil cylinder may be used as a power source to drive the piston 112 to reciprocate.

[0055] The measuring device also includes a controller, which is signal-connected to the injection pump 11, the first control valve 12, the second control valve 13, the catalytic furnace 14, the infrared optical platform 21 and the methane detection module 22. Automatic control of the detection process can be achieved.

[0056] The working principle of the non-methane total hydrocarbon measurement device 100 using the catalytic oxidation-non-dispersive infrared method of the present application is:

[0057] During measurement, the first control valve 12 connects the inlet and outlet of the injection pump 11 to the outside, and the inlet and outlet of the injection pump 11 are not connected to the second control valve 13. At this time, the injection pump 11 absorbs the sample gas. After the sample gas is fully mixed in the injection pump 11, the first control valve 12 controls the inlet and outlet of the injection pump 11 to be not connected to the outside, and the inlet and outlet of the injection pump 11 are connected to the second control valve 13. The second control valve 13 controls the sample gas to directly enter the infrared optical platform 21 and the methane detection module 22 without passing through the catalytic furnace 14 (the concentration of methane is not measured at this time), and the concentration of carbon dioxide originally contained in the sample gas, that is, the concentration of background carbon dioxide (C1) is measured; then the second control valve 13 controls the sample gas to first pass through the catalytic furnace 14 for catalytic oxidation reaction, catalyzes the carbon atoms of non-methane total hydrocarbons in the sample gas into carbon dioxide, and then enters the infrared optical platform 21 to measure the concentration of carbon dioxide after oxidation (C2). Because methane cannot be catalyzed, the concentration of methane can be accurately measured by the methane detection module 22. According to the principle of carbon conservation, the difference (C2-C1) between the concentration of carbon dioxide after catalysis (C2) and the concentration of background carbon dioxide (C1) is equal to the concentration of non-methane total hydrocarbons in the sample gas. The carbon concentration is used to characterize the VOC content, and the concentration of total hydrocarbons is the sum of the concentration of non-methane total hydrocarbons and the concentration of methane.

[0058] Second embodiment:

[0059] like Figure 3 As shown, a non-methane total hydrocarbon measuring device 100 using a catalytic oxidation-non-dispersive infrared method is a second embodiment of the utility model. The measuring device of this embodiment is similar in structure to the measuring device of the first embodiment, except that, in this embodiment, the first control valve 12 includes a first two-way solenoid valve 121 and a second two-way solenoid valve 122, and the second control valve 13 includes a third two-way solenoid valve 131 and a fourth two-way solenoid valve 132.

[0060] Specifically, the air inlet of the first two-way solenoid valve 121 is connected to the outside, and the air outlet is connected to the inlet and outlet of the injection pump 11; the air inlet of the second two-way solenoid valve 122 is connected to the inlet and outlet of the injection pump 11, and the air outlet is connected to the air inlet of the third two-way solenoid valve 131 and the air inlet of the fourth two-way solenoid valve 132; the air outlet of the third two-way solenoid valve 131 is connected to the air inlet of the catalytic furnace 14, and the air outlet of the fourth two-way solenoid valve 132 is connected to the air inlet of the infrared optical platform 21.

[0061] The working order of the first control valve 12 and the second control valve 13 of the present embodiment is: when inhaling, the first two-way solenoid valve 121 is connected, and the second two-way solenoid valve 122, the third two-way solenoid valve 131 and the fourth two-way solenoid valve 132 remain closed; when measuring the background carbon dioxide concentration, the first two-way solenoid valve 121 and the third two-way solenoid valve 131 are closed, and the second two-way solenoid valve 122 and the fourth two-way solenoid valve 132 are connected; when measuring the carbon dioxide concentration after oxidation, the first two-way solenoid valve 121 and the fourth two-way solenoid valve 132 are closed, and the second two-way solenoid valve 122 and the third two-way solenoid valve 131 are connected.

[0062] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-methane total hydrocarbon measurement device (100) using a catalytic oxidation-non-dispersive infrared method, characterized in that: The invention comprises a catalytic oxidation mechanism (10) and a detection mechanism (20), wherein the catalytic oxidation mechanism (10) comprises an injection pump (11), a first control valve (12), a second control valve (13) and a catalytic furnace (14), wherein the first control valve (12) is connected to the inlet and outlet of the injection pump (11), and the second control valve (13) is connected to the first control valve (12) and the catalytic furnace (14); the detection mechanism (20) comprises an infrared optical platform (21) and a methane detection module (22), wherein the air inlet of the infrared optical platform (21) is connected to the air outlet of the catalytic furnace (14) and the second control valve (13), and the air outlet of the infrared optical platform (21) is connected to the air inlet of the methane detection module (22); the first control valve (12) is used to control whether the inlet and outlet of the injection pump (11) are connected to the outside or the second control valve (13), and the second control valve (13) is used to control whether the catalytic furnace (14) is connected between the inlet and outlet of the injection pump (11) and the air inlet of the infrared optical platform (21).

2. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 1 is characterized in that: The first control valve (12) and the second control valve (13) are both three-way solenoid valves; the common end of the first control valve (12) is connected to the inlet and outlet of the injection pump (11); the normally closed end of the first control valve (12) is connected to the outside; the normally open end of the first control valve (12) is connected to the common end of the second control valve (13); the normally closed end of the second control valve (13) is connected to the air inlet of the infrared optical platform (21); and the normally open end of the second control valve (13) is connected to the air inlet of the catalytic furnace (14).

3. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 1 is characterized in that: The first control valve (12) comprises a first two-way solenoid valve (121) and a second two-way solenoid valve (122), and the second control valve (13) comprises a third two-way solenoid valve (131) and a fourth two-way solenoid valve (132); The air inlet of the first two-way solenoid valve (121) is connected to the outside, and the air outlet is connected to the inlet and outlet of the injection pump (11); the air inlet of the second two-way solenoid valve (122) is connected to the inlet and outlet of the injection pump (11), and the air outlet is connected to the air inlet of the third two-way solenoid valve (131) and the air inlet of the fourth two-way solenoid valve (132); the air outlet of the third two-way solenoid valve (131) is connected to the air inlet of the catalytic furnace (14), and the air outlet of the fourth two-way solenoid valve (132) is connected to the air inlet of the infrared optical platform (21).

4. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 3 is characterized in that: It also includes a heating box (30), wherein the injection pump (11), the first control valve (12), the second control valve (13) and the catalytic furnace (14) are built into the heating box (30), and the infrared optical platform (21) and the methane detection module (22) are installed on the outer wall of the heating box (30).

5. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 4 is characterized in that: The operating temperature range of the heating box (30) is 100-140 degrees Celsius.

6. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 4 is characterized in that: The first control valve (12) and the second control valve (13) are high temperature resistant solenoid valves.

7. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 1 is characterized in that: The injection pump (11) comprises an air cylinder (111), a piston (112), a push rod (113) and a power piece (114); an inlet and an outlet are arranged at one end of the air cylinder (111); the piston (112) is built into the air cylinder (111); the push rod (113) extends into the air cylinder (111) from an end away from the inlet and an outlet and is connected to the piston (112); the power piece (114) is used to drive the push rod (113) to perform reciprocating linear motion along the axial direction of the air cylinder (111).

8. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 7 is characterized in that: The piston (112) is made of polytetrafluoroethylene.

9. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 7, characterized in that: The power member (114) is a motor, the output end of the motor is connected to a lead screw (115), and the push rod (113) is connected to a nut (116) that is transmission-matched with the lead screw (115).

10. The non-methane total hydrocarbon measurement device (100) using catalytic oxidation-non-dispersive infrared method according to claim 1, characterized in that: It also includes a controller, which is signal-connected to the injection pump (11), the first control valve (12), the second control valve (13), the catalytic furnace (14), the infrared optical platform (21) and the methane detection module (22).

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