A nitrogen oxide analyzer

Abstract

The invention discloses a nitrogen oxide analyzer, comprising a reaction chamber, a photomultiplier tube arranged in the reaction chamber, a signal processor connected to the photomultiplier tube signal, and a gas input device to be measured and an ozone input device connected to the reaction chamber. The gas input device to be measured comprises a double-layer tube, a five-way valve, a temporary storage tank for gas to be measured and a molybdenum furnace which are arranged in sequence. The temporary storage tank for gas to be measured comprises a sealed tank body and a pressure membrane arranged in the sealed tank body. The pressure membrane separates the sealed tank body into a gas area to be measured and a pressure gas area. The gas area to be measured is connected with a gas inlet to be measured and a gas outlet to be measured. The pressure gas area is connected with a pressure gas inlet and a pressure gas outlet. The five-way valve and the molybdenum furnace are respectively connected to the gas inlet to be measured and the gas outlet to be measured. The pressure gas inlet and the pressure gas outlet are respectively connected with a pressure gas intake pump and a pressure gas exhaust valve. The nitrogen oxide analyzer of the invention effectively ensures that the content of the gas to be measured is the same when NO and the total nitrogen content are detected and calculated.

Description

Technical Field

[0001] The invention belongs to the field of gas monitoring and detection, and more specifically relates to a nitrogen oxide analyzer. Background Art

[0002] Since NO is unstable, it quickly turns into NO2 in the air due to ultraviolet rays and ozone, causing irritation. Nitrogen oxides mainly damage the respiratory tract. In the early stage of inhalation, there are only mild eye and respiratory irritation symptoms, such as throat discomfort and dry cough. Delayed pulmonary edema and adult respiratory distress syndrome often occur after a latent period of several hours to more than ten hours or longer, with chest tightness, respiratory distress, cough, foamy sputum, cyanosis, etc., and may be complicated by pneumothorax and mediastinal emphysema. Delayed obstructive bronchiolitis may occur about two weeks after the pulmonary edema subsides. High NO concentration can cause methemoglobinemia and other diseases, seriously affecting the health and life span of human beings and other organisms.

[0003] In the prior art, it is necessary to monitor the content of NO or nitrogen oxides in many places, strictly control and master the content of NO or nitrogen oxides in the gas to ensure absorption, elimination or conversion to avoid harm to the human body or organisms. In the prior art, the detection or monitoring of NO mainly uses ultraviolet detection method, that is, NO is converted into excited state NO2 under excessive ozone oxidation, and the excited state NO2 will emit light with a wavelength of 600-1200nm during the process of returning to the ground state NO2. The light intensity signal is detected by a photomultiplier tube to judge the content of NO2 and convert it into NO content.

[0004] In the prior art, nitrogen oxide detection equipment has a complex structure, and it is difficult to ensure that the gas content detected in the same set of data is calculated during detection, which affects the detection accuracy and real-time monitoring. Summary of the invention

[0005] The object of the present invention is to provide a nitrogen oxide analyzer which can effectively ensure that the contents of the gas to be measured are the same when NO and the total nitrogen content are detected and calculated.

[0006] The technical solution of the present invention is a nitrogen oxide analyzer, comprising a reaction chamber, a photomultiplier tube arranged in the reaction chamber, a signal processor connected to the photomultiplier tube signal, and a test gas input device and an ozone input device connected to the reaction chamber, the test gas input device comprises a double-layer tube, a five-way valve, a test gas temporary storage tank and a molybdenum furnace arranged in sequence, the test gas temporary storage tank comprises a sealed tank body and a pressure membrane arranged in the sealed tank body, the pressure membrane separates the sealed tank body into a test gas area and a pressure gas area, the test gas area is connected to a test gas inlet and a test gas outlet, the pressure gas area is connected to a pressure gas inlet and a pressure gas outlet, the five-way valve and the molybdenum furnace are respectively connected to the test gas inlet and the test gas outlet, and the pressure gas inlet and the pressure gas outlet are respectively connected to a pressure gas intake pump and a pressure gas exhaust valve.

[0007] Preferably, the double-layer tube includes an inner tube and an outer tube, and an inner tube air inlet and an inner tube exhaust port are respectively provided at both ends of the inner tube. The outer tube is connected to an outer tube air inlet for inputting balancing gas into the outer tube, and the inner tube exhaust port is connected to the five-way valve to input the gas to be tested into the five-way valve. The inner tube air inlet is connected to an input pump for the gas to be tested.

[0008] Preferably, the exhaust port of the gas input pump to be tested is connected to a first oxidation filter and a first air duct in parallel, and the air outlet of the first oxidation filter and the end of the first air duct away from the gas input pump to be tested are both connected to the inner tube air inlet on the inner tube of the double-layer tube.

[0009] Preferably, the five-way valve includes a total air inlet connected to the inner tube exhaust port on the inner tube of the double-layer tube, a first air outlet connected to the test gas inlet of the sealed tank, a second air outlet connected to the ozone input device, a third air outlet connected to the outer tube air inlet on the outer tube of the double-layer tube, and a fourth air outlet connected to the external environment.

[0010] Preferably, the molybdenum furnace includes a furnace body, a molybdenum heating wire placed in the furnace body, and a molybdenum furnace air inlet and a molybdenum furnace air outlet arranged on the furnace body, the molybdenum furnace air inlet is connected to the test gas outlet of the sealed tank body, and the molybdenum furnace air outlet is connected to the reaction chamber; an air guide coil is also arranged in the furnace body, and both ends of the air guide coil extend out of the furnace body and are respectively connected to the exhaust gas outlet of the reaction chamber and the external environment.

[0011] Preferably, a second air duct is connected to the outlet of the gas to be tested of the sealed tank body, and the second air duct is arranged in parallel with the molybdenum furnace and the other end of the second air duct is connected to the reaction chamber.

[0012] Preferably, the ozone input device comprises a second oxidation filter and an ozone generator which are arranged in sequence, the air inlet of the second oxidation filter is connected to the second air outlet of the five-way valve, and the air outlet of the ozone generator is connected to the reaction chamber.

[0013] Preferably, the exhaust gas outlet of the reaction chamber is connected to the air inlet of the second oxidation filter, and the air outlet of the second oxidation filter is connected to one end of the air guide coil in the molybdenum furnace.

[0014] The beneficial effects of a nitrogen oxide analyzer of the technical solution of the present invention are:

[0015] 1. By setting up a gas storage tank, the gas to be tested obtained from a single sampling is collected, and then the NO and total nitrogen content are tested respectively to ensure that the contents of the gas to be tested for NO and total nitrogen are consistent, thereby improving the accuracy of the test.

[0016] 2. By collecting and treating the post-reaction gas in the reaction chamber, the emission of ozone and excited nitrogen dioxide, nitric oxide and ozone can be avoided, thus protecting the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a block diagram of the principles of a nitrogen oxide analyzer according to the technical solution of the present invention.

[0018] Figure 2 This is a schematic diagram of gas transportation during calibration of this nitrogen oxide analyzer.

[0019] Figure 3 This is a gas transport diagram of the nitrogen oxide analyzer when detecting NO.

[0020] Figure 4 This is a gas transport diagram of the nitrogen oxide analyzer when detecting the total nitrogen content.

[0021] Figure 5 Schematic diagram of gas transportation when exhaust gas is discharged from the reaction chamber. DETAILED DESCRIPTION

[0022] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0023] like Figure 1As shown, the technical solution of the present invention is a nitrogen oxide analyzer, comprising a reaction chamber 7, a photomultiplier tube 10 arranged in the reaction chamber 7, a signal processor connected to the photomultiplier tube 10, and a gas input device to be measured and an ozone input device connected to the reaction chamber 7. The ozone input device generates ozone and inputs the ozone into the reaction chamber 7, and uses the ozone to oxidize NO transported into the reaction chamber through the gas input device to be measured, so that NO in the gas is excited and converted into excited NO2, and the excited NO2 is extremely unstable. The excited NO2 releases light energy in the process of returning to the ground state of NO2, and the light signal is received by the photomultiplier tube 10, and the light signal is transmitted to the signal processor, and the signal processor analyzes it to obtain the NO2 concentration, and the NO concentration or the total nitrogen content in the gas to be measured is measured by calculation.

[0024] In the present technical solution, the input device for the gas to be measured includes a double-layer tube 3, a five-way valve 4, a temporary storage tank 5 for the gas to be measured and a molybdenum furnace 6 which are arranged in sequence. The temporary storage tank 5 for the gas to be measured includes a sealed tank body and a pressure membrane 53 arranged in the sealed tank body. The pressure membrane 53 separates the sealed tank body into a gas area 51 to be measured and a pressure gas area 52. The gas area 51 to be measured is connected with an inlet 55 for the gas to be measured and an outlet 55 for the gas to be measured. The pressure gas area 52 is connected with an inlet 56 for the pressure gas and an outlet 57 for the pressure gas. The five-way valve 4 and the molybdenum furnace 6 are respectively connected with the inlet 54 for the gas to be measured and the outlet 55 for the gas to be measured. The pressure gas inlet 56 and the outlet 57 are respectively connected with a pressure gas intake pump and a pressure gas exhaust valve.

[0025] Based on the above technical solution, firstly, sufficient sampled gas to be tested is input into the gas area 51 of the gas storage tank 5 to be tested for temporary storage, and then the gas sampling is suspended or the gas is input into the gas area 51 of the gas storage tank 5 to be tested. Instead, a certain amount of pressure regulating gas is input into the pressure gas area 52 of the gas storage tank 5 to be tested through the pressure gas inlet pump, and the pressure membrane 53 is squeezed by the pressure regulating gas, so that the pressure membrane 53 squeezes the gas to be tested in the gas area 51 to be tested, and the gas to be tested in the gas area 51 to be tested is output from the gas outlet 55 to the reaction chamber 7. After the gas to be tested enters the reaction chamber 7, it is excited and oxidized under the action of ozone, so as to detect the amount of nitric oxide or the total amount of nitrogen in the gas to be tested, and the information of the amount of nitric oxide or the total amount of nitrogen is stored through the signal processor.

[0026] After the operation process of the previous section is completed, the gas in the reaction chamber 7 is evacuated, and then a certain amount of pressure regulating gas is continuously input into the pressure gas area 52 of the temporary storage tank 5 of the gas to be measured through the pressure gas inlet pump, and the pressure regulating gas continues to squeeze the pressure membrane 53, so that the pressure membrane 53 continues to squeeze the gas to be measured in the gas to be measured area 51, and the gas to be measured in the gas to be measured area 51 continues to be output to the reaction chamber 7 through the gas to be measured outlet 55. After the gas to be measured enters the reaction chamber 7, it is excited and oxidized under the action of ozone, and the total amount of nitrogen or nitric oxide in the gas to be measured is detected, and the information is saved by the signal processor, and the amount of NO, NO2 and the total amount of nitrogen in the gas to be measured is calculated with the amount of nitric oxide or the total amount of nitrogen obtained by the previous detection, and the amount of NO, NO2 and the total amount of nitrogen in the gas to be measured is obtained.

[0027] Based on the above technical scheme, through the setting of the temporary storage tank 5 for the gas to be tested and the method of discharging the gas to be tested, sufficient gas to be tested with consistent component content can be obtained after one sampling or continuous sampling for a period of time, and then the amounts of NO, NO2 and total nitrogen content in the gas to be tested are detected to improve the detection accuracy and avoid the concentration or content of the gas to be tested changing too fast when detecting the amount of NO and the total nitrogen content, thereby affecting the detection precision and accuracy.

[0028] In the technical solution, the double-layer tube 3 includes an inner tube 31 and an outer tube 32. The inner tube 31 is provided with an inner tube air inlet 33 and an inner tube exhaust port 34 at both ends, and the outer tube 32 is connected with an outer tube air inlet 35 for inputting balancing gas into the outer tube. The inner tube exhaust port 34 is connected with the five-way valve 4, and the gas to be measured is input into the five-way valve 5. The inner tube air inlet 33 is connected with the gas input pump 1 to be measured.

[0029] By providing the double-layer tube 3, water vapor in the gas entering the reaction chamber 7 is removed to prevent water vapor from absorbing light generated in the reaction chamber during the gas detection, thereby affecting the detection effect. In the double-layer tube 3, gas is added to the outer tube through the outer tube air inlet 35 to ensure that the air pressure in the inner tube and the outer tube is balanced, so as to facilitate the discharge of water vapor in the gas to be detected.

[0030] In the technical solution, the exhaust port 11 of the gas input pump 1 to be tested is connected to the first oxidation filter 2 and the first air guide tube 20 in parallel. The gas outlet 21 of the first oxidation filter 2 and the end of the first air guide tube 20 away from the gas input pump 1 to be tested are both connected to the inner tube inlet 33 on the inner tube 31 of the double-layer tube 3.

[0031] A strong oxidant is arranged in the first oxidation filter 2. When the gas to be measured passes through the first oxidation filter 2, NO in the gas to be measured is oxidized to NO2. Figure 2As shown, before detection, when the analyzer is calibrated, the gas to be tested first passes through the first oxidation filter 2, and the NO in the gas to be tested is oxidized into NO2. The gas containing only NO2 does not pass through the molybdenum furnace 6, but directly enters the reaction chamber 7. Because the ground state NO2 will not react with ozone, no light energy is generated inside the reaction chamber 7. At this time, the photomultiplier tube 10 will not obtain a light signal, and the signal processor connected to it has zero information, thereby realizing the calibration of the analyzer.

[0032] In the technical solution, the five-way valve 4 includes a total air inlet 41 connected to the inner tube exhaust port 34 on the inner tube 31 of the double-layer tube 3, a first air outlet 43 connected to the test gas inlet 54 of the sealed tank body, a second air outlet 44 connected to the ozone input device, a third air outlet 42 connected to the outer tube air inlet 35 on the outer tube 32 of the double-layer tube 3, and a fourth air outlet 45 connected to the external environment. The five-way valve 4 is set to supply air to the ozone generator, to the test gas temporary storage tank 5, and to the outer tube of the double-layer tube. The fourth air outlet 45 is connected to the external environment, and the excess gas can be directly discharged into the environment.

[0033] In the present technical solution, the molybdenum furnace 6 includes a furnace body, a molybdenum heating wire placed in the furnace body, and a molybdenum furnace air inlet 62 and a molybdenum furnace air outlet 63 arranged on the furnace body. The molybdenum furnace air inlet 62 is connected to the test gas outlet 55 of the sealed tank body, and the molybdenum furnace air outlet 63 is connected to the reaction chamber 7. An air guide coil 61 is also provided in the furnace body, and both ends of the air guide coil 61 extend out of the furnace body and are respectively connected to the exhaust gas outlet 71 of the reaction chamber 7 and the external environment.

[0034] Based on the above technical solution, the gas to be tested enters the molybdenum furnace 6, and the working principle of the molybdenum furnace is: molybdenum acts as a catalyst to convert NO2 into NO and O2 at a high temperature of 315°C. When the total amount of nitrogen in the gas to be tested is tested, the molybdenum furnace 6 converts all NO2 in the gas to be tested into NO, and the total NO content is measured. Then, the amount of NO2, NO and the total amount of nitrogen in the gas to be tested is calculated by measuring the single NO content in the gas to be tested.

[0035] Based on the above technical solution, an air guide coil 61 is arranged in the molybdenum furnace, and both ends of the air guide coil 61 extend out of the furnace body and are respectively connected to the exhaust gas outlet 71 of the reaction chamber 7 and the external environment. That is, after the reaction in the reaction chamber 7 is completed and this measurement is completed, the exhaust gas in the reaction chamber 7 is passed into the air guide coil 61, and the gas (mainly O3) in the air guide coil 61 is heated by the high temperature in the molybdenum furnace 6, and O3 is decomposed into O2, which is directly discharged into the air.

[0036] In the present technical solution, the test gas outlet 55 of the sealed tank is also connected to a second air guide pipe 60, which is arranged in parallel with the molybdenum furnace 6 and the other end of which is connected to the reaction chamber 7. When the NO content in the test gas is detected, the test gas is directly transported to the reaction chamber 7 through the second air guide pipe 60 without passing through the molybdenum furnace 6, so as to avoid NO2 in the test gas being reduced to NO and affecting the detection result.

[0037] In the present technical solution, the ozone input device includes a second oxidation filter 8 and an ozone generator 9 which are arranged in sequence. The air inlet 81 of the second oxidation filter 8 is connected to the second air outlet 44 of the five-way valve 4, and the air outlet 91 of the ozone generator 9 is connected to the reaction chamber 7. The second oxidation filter 8 is set to oxidize NO in the gas into NO2, and then enter the ozone generator 9 together with oxygen. The ozone generator 9 is ionized at high pressure to oxidize oxygen into ozone, and finally transported to the reaction chamber for reaction with NO. The second oxidation filter 8 is set to oxidize NO in the gas into NO2, so as to prevent NO from entering the reaction chamber through the ozone generator 9 and affecting the detection accuracy.

[0038] In this technical solution, the exhaust gas outlet 72 of the reaction chamber 7 is connected to the air inlet 81 of the second oxidation filter 8, and the air outlet 82 of the second oxidation filter 8 is connected to one end of the air guide coil 61 in the molybdenum reduction furnace 6. After the reaction in the reaction chamber 7 is completed and this test is completed, the gas in the reaction chamber 7 is transported to the second oxidation filter 8 by the pump 70, and the gas after the reaction in the reaction chamber 7 is oxidized and then passed through the air guide coil 61 for heating and decomposition, so that the ozone is decomposed into oxygen and discharged directly to avoid pollution to the air environment.

[0039] The detection process is:

[0040] Step 1: Calibrate the NOx analyzer. At this time, the gas transmission path is as follows: Figure 2 As shown: the gas to be tested passes through the first oxidation filter 2, NO in the gas to be tested is oxidized to NO2, and finally the gas to be tested passes through the double-layer tube 3, the five-way valve 4, the temporary storage tank 5 for the gas to be tested, and the second air guide pipe 60 in sequence, and finally enters the reaction chamber 7. At the same time, part of the gas to be tested is output by the five-way valve 4 and passes through the second oxidation filter 8 and the ozone generator 9 in sequence, and the oxygen in the gas is oxidized to ozone. Ozone and NO2 enter the reaction chamber, and no reaction can be carried out in the reaction chamber, the photomultiplier tube cannot obtain an optical signal, and the signal processor should obtain a zero signal. This step is used as a nitrogen oxide analyzer for calibration.

[0041] Step 2: Detect NO in the gas to be tested. At this time, the gas delivery path is as follows: Figure 3As shown. First, a sufficient diameter of the sampled gas to be tested is sequentially input into the double-layer tube 3, the five-way valve 4 and the temporary storage tank 5 of the gas to be tested through the first gas guide pipe 20. Sufficient gas to be tested is input into the gas area 51 of the temporary storage tank 5 of the gas to be tested for temporary storage, and then the gas sampling is suspended or gas is input into the gas area 51 of the temporary storage tank 5 of the gas to be tested. Instead, a certain amount of pressure regulating gas is input into the pressure gas area 52 of the temporary storage tank 5 of the gas to be tested through the pressure gas inlet pump, and the pressure membrane 53 is squeezed by the pressure regulating gas, so that the pressure membrane 53 squeezes the gas to be tested in the gas area 51 to be tested, and the gas to be tested in the gas area 51 to be tested is output from the gas outlet 55 to be tested, and directly transported to the reaction chamber 7 through the second gas guide pipe 60. At the same time, part of the gas to be measured is output by the five-way valve 4 and passes through the second oxidation filter 8 and the ozone generator 9 in sequence. The second oxidation filter 8 oxidizes the NO in the gas into NO2, and the ozone generator 9 oxidizes the oxygen in the gas into ozone, and the ozone and NO2 enter the reaction chamber. After the NO in the gas to be measured enters the reaction chamber 7, it is excited and oxidized under the action of ozone, realizing the detection of the amount of nitric oxide in the gas to be measured, and the information of the amount of nitric oxide is saved through the signal processor.

[0042] Step 3: Detect the total amount of nitrogen in the gas to be tested. At this time, the gas delivery path is as follows: Figure 4 As shown. After the operation process of the second step is completed, the gas in the reaction chamber 7 is emptied, and then a certain amount of pressure regulating gas is continuously input into the pressure gas area 52 of the temporary storage tank 5 of the gas to be measured through the pressure gas inlet pump, and the pressure regulating gas continues to squeeze the pressure membrane 53, so that the pressure membrane 53 continues to squeeze the gas to be measured in the gas area 51 to be measured, and the gas to be measured in the gas area 51 continues to be output from the gas outlet 55 to be measured, and then the gas to be measured enters the molybdenum furnace 6, and the molybdenum furnace 6 reduces the NO2 in the gas to be measured to NO, and all the NO is transported to the reaction chamber 7. At the same time, the gas input pump 1 to be measured continues to work, and part of the gas is transported into the second oxidation filter 8 and the ozone generator 9 through the five-way valve 4, and the excess gas is discharged into the air from the fourth gas outlet 45 of the five-way valve 4. The gas is output by the five-way valve 4 and passes through the second oxidation filter 8 and the ozone generator 9 in sequence. The second oxidation filter 8 oxidizes the NO in the gas into NO2, and the ozone generator 9 oxidizes the oxygen in the gas into ozone, and the ozone and NO2 enter the reaction chamber. After the gas to be measured (all NO) enters the reaction chamber 7, it is excited and oxidized under the action of ozone, and the total amount of nitrogen in the gas to be measured is detected. The information is saved by the signal processor and calculated with the amount of nitric oxide detected in the second step to obtain the total amount of nitrogen in the gas to be measured. Finally, the amount of NO, NO2 and the total amount of nitrogen in the gas to be measured is calculated.

[0043] In the fourth step, after each reaction in the reaction chamber 7 is completed, the gas in the reaction chamber is discharged and oxidized to be directly discharged, such as Figure 5The gas in the reaction chamber 7 is evacuated by the pump 70 and transported to the second oxidation filter 8, which oxidizes the gas and then transports the gas to the gas guide coil 61 in the molybdenum furnace 6. The gas guide coil 61 is heated to decompose the gas therein, and the ozone is decomposed into oxygen for direct discharge.

[0044] The technical solution of the present invention is described above in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A nitrogen oxide analyzer, comprising a reaction chamber, a photomultiplier tube arranged in the reaction chamber, a signal processor connected to the photomultiplier tube signal, and a gas input device to be measured and an ozone input device connected to the reaction chamber, characterized in that: The gas input device to be measured includes a double-layer tube, a five-way valve, a temporary storage tank for gas to be measured and a molybdenum furnace which are arranged in sequence. The temporary storage tank for gas to be measured includes a sealed tank body and a pressure membrane arranged in the sealed tank body. The pressure membrane separates the sealed tank body into a gas area to be measured and a pressure gas area. The gas area to be measured is connected with a gas inlet to be measured and a gas outlet to be measured. The pressure gas area is connected with a pressure gas inlet and a pressure gas outlet. The five-way valve and the molybdenum furnace are respectively connected with the gas inlet to be measured and the gas outlet to be measured. The pressure gas inlet and the pressure gas outlet are respectively connected with a pressure gas intake pump and a pressure gas exhaust valve. The double-layer tube comprises an inner tube and an outer tube, the inner tube is provided with an inner tube air inlet and an inner tube air outlet at both ends, the outer tube is connected with an outer tube air inlet for inputting balancing air into the outer tube, the inner tube air outlet is connected with the five-way valve, the gas to be tested is input into the five-way valve, and the inner tube air inlet is connected with a gas input pump to be tested; The exhaust port of the gas input pump to be tested is connected to a first oxidation filter and a first air guide pipe in parallel, and the gas outlet of the first oxidation filter and the end of the first air guide pipe away from the gas input pump to be tested are both connected to the inner tube air inlet on the inner tube of the double-layer tube; The outlet of the gas to be tested of the sealed tank is also connected to a second air guide pipe, which is arranged in parallel with the molybdenum furnace and the other end of which is connected to the reaction chamber.

2. A nitrogen oxide analyzer according to claim 1, characterized in that: The five-way valve includes a total air inlet connected to the inner tube exhaust port on the inner tube of the double-layer tube, a first air outlet connected to the test gas inlet of the sealed tank body, a second air outlet connected to the ozone input device, a third air outlet connected to the outer tube air inlet on the outer tube of the double-layer tube, and a fourth air outlet connected to the external environment.

3. A nitrogen oxide analyzer according to claim 1, characterized in that: The molybdenum furnace includes a furnace body, a molybdenum heating wire placed in the furnace body, and a molybdenum furnace air inlet and a molybdenum furnace air outlet arranged on the furnace body. The molybdenum furnace air inlet is connected to the test gas outlet of the sealed tank body, and the molybdenum furnace air outlet is connected to the reaction chamber; an air guide coil is also arranged in the furnace body, and both ends of the air guide coil extend out of the furnace body and are respectively connected to the exhaust gas outlet of the reaction chamber and the external environment.

4. A nitrogen oxide analyzer according to claim 1, characterized in that: The ozone input device comprises a second oxidation filter and an ozone generator which are arranged in sequence, the air inlet of the second oxidation filter is connected to the second air outlet of the five-way valve, and the air outlet of the ozone generator is communicated with the reaction chamber.

5. A nitrogen oxide analyzer according to claim 4, characterized in that: The exhaust gas outlet of the reaction chamber is connected to the air inlet of the second oxidation filter, and the air outlet of the second oxidation filter is connected to one end of the air guide coil in the molybdenum furnace.

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