A NOx measurement system and method based on current signals of nitrogen ions in flames

Abstract

The invention discloses a NO based on the current signal of N ions in flame. x Measurement system and method, the NO x The measurement system includes: a burner, a combustion chamber, a flue gas filter, a quadrupole mass analyzer 1, a quadrupole mass analyzer 2, a positive ion collector, a negative ion collector, a current amplifier, a current signal processor and a computer. The system is mainly based on the fact that the combustion process of hydrocarbon fuel and air oxidant will produce N-containing ions (mainly NO + and NO2 ‑ ), and the concentrations of these two ions have an obvious positive correlation with NO and NO2 in flue gas. By using a quadrupole mass analyzer to analyze the target ion NO in flue gas, + and NO2 ‑ The positive and negative ions are collected and converted into current signals by positive and negative ion collectors. The corresponding NO and NO2 concentration values ​​are obtained through current signal processing and empirical correlation conversion to achieve NO x The device of the present invention is simple and highly sensitive, and can realize NO x Rapid electrical measurement of emissions.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion pollutant emission analysis and measurement, and in particular to a nitrogen oxide concentration electrical measurement system and method. Background Art

[0002] Nitrogen oxides, usually nitrogen dioxide and nitrogen monoxide, are byproducts of many industrial processes, especially in the combustion of fossil fuels and biomass fuels. Nitrogen oxides have certain hazards to the environment and human health. In view of these hazards, it is very important to monitor nitrogen oxide concentrations, which can not only help us understand air quality and environmental health, but also provide a basis for formulating policies to reduce nitrogen oxide emissions. Through monitoring, we can also identify the main sources of pollution so that more effective control measures can be taken.

[0003] At present, there are mainly the following methods for measuring the concentration of nitrogen oxides at home and abroad: (1) Chemical absorption method: This is the most common measurement method. It uses a chemical reagent (usually a solution containing ferrous sulfate) to absorb nitrogen oxides, and determines the concentration of nitrogen oxides by measuring the chemical reaction in the solution after absorption. (2) Infrared spectroscopy: This method uses an infrared spectrometer to measure the absorption of nitrogen oxides at a specific wavelength to derive their concentration. This method has high accuracy, but the equipment is complex and the cost is relatively high. (3) Ultraviolet absorption spectroscopy: This method determines the concentration of nitrogen oxides by measuring the absorption of nitrogen oxides in a specific ultraviolet light band. The operation is simple but the accuracy is slightly lower than that of infrared spectroscopy. The overall optical detection principles include non-dispersive infrared (NDIR), microflow NDIR, non-dispersive ultraviolet (NDUV), and ultraviolet differential absorption spectroscopy (UV-DOAS). The detection principles are different, and the measurement accuracy and results are also different. In addition to the different detection principles, there are also two differences in measurement methods: one is direct measurement, which measures NO x It is divided into two components, NO and NO2, and the measured concentrations are added to get NO x The other is indirect measurement, which uses a converter to convert NO2 into NO, and indirectly obtains NO2 and NO by measuring NO. x concentration.

[0004] At present, the traditional method of measuring nitrogen oxides is mainly based on optical means, but its convenience needs to be improved. For situations where rapid on-site measurement of nitrogen oxide concentrations is required, methods such as infrared spectroscopy, which require complex equipment and difficult operation, are not very suitable. At the same time, infrared spectroscopy and ultraviolet absorption spectroscopy require complex instruments and equipment, which greatly increases the cost of measurement. Summary of the invention

[0005] The present invention aims at the problem of effective and rapid measurement of nitrogen oxide concentration in the combustion process, and takes a unique approach. The combustion process of hydrocarbon fuels will produce nitrogen-containing charged ions, and the main nitrogen-containing positive and negative charged ions NO + and NO2 - The latest research found that there is an obvious conversion correlation and correspondence between NO and NO2 produced during the combustion process. A NOx measurement system and method based on the current signal of N ions in the flame was proposed, which effectively made up for the shortcomings of the existing optical measurement methods.

[0006] The purpose of the present invention is achieved through the following technical solutions: a NOx measurement system and method based on the current signal of N ions in the flame, the NOx measurement system comprising: a burner, a combustion chamber, a flue gas filter, a quadrupole mass analyzer 1, a quadrupole mass analyzer 2, a positive ion collector, a negative ion collector, a current amplifier, a current signal processor and a computer and other devices. The burner is placed in the combustion chamber, the combustion chamber is in a closed state as a whole, and a flue gas channel is left at the upper end, the flue gas channel is led out from the combustion chamber and connected to the flue gas filter; after passing through the flue gas filter, it is divided into two paths and connected to the quadrupole mass analyzer 1 and the quadrupole mass analyzer 2 respectively; the quadrupole mass analyzer 1 and the quadrupole mass analyzer 2 are respectively installed with positive and negative ion collectors to collect ion NO screened by the quadrupole mass analyzer. + and NO2 - , and convert it into a current signal; a current amplifier is connected to the positive and negative ion collectors for current signal amplification; a current signal processor is installed after the current amplifier, and the current signal processor converts NO, NO2 and NO obtained in the previous scientific research into + and NO2 - The measurement of the current signal generated by the ion concentration corresponds to the line graph and the experimental experience correlation formula. The corresponding current signal is processed to obtain the concentration values ​​of NO and NO2. Finally, the corresponding signal is stored and displayed on the computer. The display content includes the current signal and the converted NO and NO2 concentration values.

[0007] A method for effectively and quickly measuring the concentration of nitrogen oxides in a combustion process using the above system comprises the following steps: a hydrocarbon fuel and an air oxidant are burned in a burner to generate nitrogen-containing ions (mainly NO + and NO2 - The flue gas is drawn out from the combustion chamber and filtered through the flue gas filter to remove the solid soot particles. Then, the flue gas is divided into two paths and enters the quadrupole mass analyzer 1 and the quadrupole mass analyzer 2 for ion screening to form the target ion NO + and NO2 - , the screened ions NO + and NO2 -The positive and negative ions are collected by the corresponding collectors and converted into current signals. The corresponding current signals are amplified by the current amplifier and then processed by the current signal processor. The current signal processor is based on the NO, NO2 and NO obtained in the previous scientific research. + and NO2 - The measurement of the current signal generated by the ion concentration corresponds to the line graph and the experimental experience correlation formula. The corresponding current signal is processed to obtain the concentration values ​​of NO and NO2. Finally, the corresponding signal is stored and displayed on the computer. The display content includes the current signal and the converted NO and NO2 concentration values.

[0008] The present invention has the following advantages:

[0009] 1. Compared with the existing chemical and optical measurement methods of nitrogen oxide concentration, the present invention innovatively measures the nitrogen oxide concentration from the nitrogen ion generated during the combustion process. x Based on the intrinsic correlation between the concentrations, the electrical signal measurement method is used to realize the nitrogen oxide NO x Concentration measurement. Since the response speed of electrical signals is faster than that of chemical methods, and the simplicity, stability and applicability of the device are wider than those of optical methods, the entire system has the advantages of low cost, good flexibility and fast measurement speed.

[0010] 2. Compared with other mass analyzers, the quadrupole mass analyzer used in the present invention is small in size, light in weight, easy to operate, fast in scanning speed, and high in resolution. By setting a suitable voltage, it can ensure that only NO + and NO2 - Successfully passed with high accuracy.

[0011] 3. The current signal processor used in the present invention is embedded with the latest combustion process containing N ion generation and nitrogen oxides NO x The corresponding line graph and experimental empirical correlation formula between concentrations are simple to calculate and have high corresponding conversion accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the overall system diagram of the present invention.

[0013] Explanation of the reference numerals: (1) burner, (2) combustion chamber, (3) flue gas filter, (4) quadrupole mass analyzer 1, (5) quadrupole mass analyzer 2, (6) positive ion collector, (7) negative ion collector, (8) current amplifier, (9) signal processor, (10) computer.

[0014] Figure 2 It is a corresponding relationship diagram between the main N-containing positive and negative charged ions in the signal processor mentioned in the present invention and the NO and NO2 produced in the combustion process. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the idea and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0016] like Figure 1 As shown, the present invention is a NO based on the current signal of N ions in the flame x Concentration measurement

[0017] The NOx measurement system comprises: (1) a burner, (2) a combustion chamber, (3) a flue gas filter, (4) a quadrupole mass analyzer 1, (5) a quadrupole mass analyzer 2, (6) a positive ion collector, (7) a negative ion collector, (8) a current amplifier, (9) a signal processor, and (10) a computer. The burner (1) is placed in the combustion chamber (2), and the combustion chamber (2) is in a sealed state as a whole, with a flue gas channel left at the upper end.

[0018] The flue gas channel is led out from the combustion chamber (2) and connected to the flue gas filter (3); after passing through the flue gas filter (3), the flue gas is divided into two paths and connected to the quadrupole mass analyzer 1 (4) and the quadrupole mass analyzer 2 (5) respectively; the quadrupole mass analyzer 1 (4) and the quadrupole mass analyzer 2 (5) are respectively equipped with positive and negative ion collectors (6) and (7) for collecting ions NO filtered by the quadrupole mass analyzer (4) and (5). + and NO2 - , and convert it into a current signal; a current amplifier (8) is connected to the positive and negative ion collectors (6) and (7) for current signal amplification; a current signal processor (9) is installed behind the current amplifier (8), and the current signal processor (9) is based on the NO, NO2 and NO obtained in the previous scientific research. + and NO2 - The measurement of the current signal generated by the ion concentration corresponds to the line graph and the experimental experience correlation formula. The corresponding current signal is processed to obtain the concentration values ​​of NO and NO2, and finally the corresponding signal is stored and displayed on the computer.

[0019] The specific implementation steps of the present invention are as follows: hydrocarbon fuel and air oxidant are burned by a burner to produce nitrogen-containing ions (mainly NO + and NO2 - The flue gas is drawn out from the combustion chamber and filtered through the flue gas filter to remove the solid soot particles. Then, the flue gas is divided into two paths and enters the quadrupole mass analyzer 1 and the quadrupole mass analyzer 2 for ion screening to form the target ion NO + and NO2 - , the screened ions NO + and NO2- The positive and negative ions are collected by the corresponding collectors and converted into current signals. The corresponding current signals are amplified by the current amplifier and then processed by the current signal processor. The current signal processor is based on the NO, NO2 and NO obtained in the previous scientific research. + and NO2 - The measurement of the current signal generated by the ion concentration corresponds to the line graph and the experimental experience correlation formula. The corresponding current signal is processed to obtain the concentration values ​​of NO and NO2. Finally, the corresponding signal is stored and displayed on the computer. The display content includes the current signal and the converted NO and NO2 concentration values.

Claims

1. A NO based on the current signal of N ions in flame x A measuring system, characterized in that: The NO x The measuring system comprises: a burner (1), a combustion chamber (2), a flue gas filter (3), a quadrupole mass analyzer 1 (4), a quadrupole mass analyzer 2 (5), a positive ion collector (6), a negative ion collector (7), a current amplifier (8), a signal processor (9), and a computer (10). The hydrocarbon fuel and the air oxidant are burned by the burner (1) to generate flue gas containing nitrogen ions. The flue gas is drawn out from the upper end of the combustion chamber (2) and filtered through the flue gas filter (3) to remove solid carbon soot particles. The flue gas is divided into two paths and enters the quadrupole mass analyzer 1 (4) and the quadrupole mass analyzer 2 (5) respectively for ion screening to form target ions NO. + and NO2 - , the screened ions NO + and NO2 - The positive and negative ion collectors (6) and (7) respectively collect and convert the ions into current signals. The corresponding current signals are amplified by the current amplifier (8) and then enter the current signal processor (9) for processing. The current signal processor calculates the NO, NO2 concentration and NO + and NO2 - The measurement of the current signal generated by the ion concentration corresponds to the line graph and the experimental experience correlation formula, and the corresponding current signal is processed to obtain the concentration values ​​of NO and NO2. Finally, the corresponding signal is stored and displayed on the computer (10). The display content includes the current signal and the converted NO and NO2 concentration values. The measurement uses the charged ions directly generated by combustion, and no additional ion source is required to achieve ionization of the measured substance.

2. The NO based on the current signal of N ions in flame according to claim 1 x A measuring system, characterized in that: By using quadrupole mass analyzer 1 (4) and quadrupole mass analyzer 2 (5), a specific voltage is applied to ensure that only NO with a single charge-to-mass ratio is detected. + and NO2 - The ions pass through two mass analyzers respectively and are finally collected by corresponding ion collectors to form current signals.

3. The NO based on the current signal of N ions in flame according to claim 1 x Measuring system, characterized in that The current signal processor (9) is embedded with NO + and NO2 - The measured corresponding line graph of current value and NO, NO2 concentration and the experimental empirical correlation formula.

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