Heating furnace combustion gas monitoring method and device based on laser Raman telemetry technology

Abstract

The invention discloses a heating furnace combustion gas monitoring method and device based on a laser Raman telemetry technology, and belongs to the technical field of Raman spectrum analysis, the heating furnace combustion gas monitoring device comprises a pulse laser and a time-gated Raman spectrometer which are arranged outside a heating furnace, and an excitation light path is arranged between the pulse laser and the heating furnace. According to the invention, simultaneous detection of multi-component gases in the combustion furnace is realized by adopting a Raman telemetry technology, the defect that homonuclear diatomic molecular gases are difficult to detect by adopting an absorption spectrum technology is made up, and a Raman signal is generated after a laser light path enters the combustion furnace through an external reflection device; and the gas is transmitted to the time-gated Raman spectrometer after being reflected and enhanced, the external reflecting device and the time-gated Raman spectrometer can realize telemetering treatment on the gas environment in the reflectivity, and monitoring equipment can realize gas measurement without being tightly attached to the surface of the heating furnace, so that the damage to the equipment caused by the high temperature of the furnace body of the combustion furnace is favorably avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of Raman spectroscopy analysis, and in particular relates to a method and device for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology. Background Art

[0002] With the further advancement of the dual carbon goals, accelerating the green and low-carbon transformation has become the only way for industrial development. As an important and high-energy-consuming equipment in industrial production, industrial heating furnaces are often used in many industries such as metallurgy, petrochemicals, and mechanical heat treatment. During the production process, heating furnaces usually need to supply specific fuel and oxygen to achieve the purpose of heating, and this process will produce a large amount of gas. The gas concentration in the combustion furnace can reflect the combustion state. Real-time monitoring of the gas component information in the heating furnace can help improve the operating efficiency of the heating furnace, reduce energy consumption, and ensure product quality and operational safety, thereby achieving the goal of energy saving and consumption reduction;

[0003] Heating furnace gas monitoring methods primarily employ extractive measurement, which involves extracting gas samples from the combustion furnace using an extraction device and employing certain sample pretreatment methods, such as condensation, filtration, and drying, to ensure the accuracy and reliability of gas analysis. The pretreated gas is then fed into a gas analyzer for analysis. While extractive measurement instruments can measure gas within heating furnaces, this method has drawbacks such as complex components, measurement lag, and easily distorted results.

[0004] Adjacent technologies include in-situ monitoring of gases in heating furnaces using TDLAS technology, which enables real-time and accurate measurement of characteristic furnace gases such as CO, O2, H2O, and CO2, providing key parameters for regulating low-oxygen combustion and low-carbon emissions in the furnace. Although this technology can achieve simultaneous measurement of multi-component gases, since TDLAS is an absorption spectroscopy technique, the device requires four lasers of different wavelengths as light sources. The device is complex and the operation process is cumbersome, and it is difficult to analyze homonuclear diatomic gases (N2, H2, etc.). Therefore, there is a problem of the need for accurate analysis of multi-component gases in heating furnaces and the lack of effective monitoring methods. Summary of the Invention

[0005] The purpose of the present invention is to propose a method and device for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology in order to solve the problem of accurate analysis of multi-component gases in the heating furnace and the lack of effective monitoring means.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A heating furnace combustion gas monitoring device based on laser Raman telemetry technology includes a pulse laser and a time-gated Raman spectrometer arranged outside the heating furnace, an excitation light path is provided between the pulse laser and the heating furnace, a window is provided on one side of the heating furnace, a reflecting device is provided at the position of the window corresponding to the furnace chamber of the heating furnace, a signal collection light path is provided between the reflecting device and the time-gated spectrometer, and the excitation light path emitted by the pulse laser passes through the window on the side of the furnace chamber of the heating furnace and enters the time-gated spectrometer after being reflected by the reflecting device.

[0008] As a further description of the above technical solution:

[0009] The reflecting device is a reflecting mirror, which is located outside the heating furnace on the side of the laser light path corresponding to the pulse laser. The combustion gas in the heating furnace is remotely measured through the external reflecting device and the time-gated spectrometer to reduce high-temperature damage.

[0010] As a further description of the above technical solution:

[0011] A shaping lens group is installed on the front side of the pulse laser, and the wavelength of the pulse laser covers the molecular absorption spectrum range of the gas component to be measured.

[0012] As a further description of the above technical solution:

[0013] Off-axis parabolic mirrors are installed on the corresponding sides of the pulse laser and the time-gated spectrometer, and the pulse laser signals are collected by the double off-axis parabolic mirrors.

[0014] As a further description of the above technical solution:

[0015] The signal collection optical path includes a time-gated spectrometer, and a lens and a filter are sequentially arranged on the light incident side.

[0016] As a further description of the above technical solution:

[0017] The utility model also includes a control and communication module, which controls the pulse laser and the time-gated Raman spectrometer to perform work control and communication.

[0018] As a further description of the above technical solution:

[0019] A heating furnace combustion gas monitoring method based on laser Raman telemetry technology includes: S1, a pulsed laser emits a first laser, which is spot-shaped and beam-expanded through an excitation optical path before reaching the heating furnace;

[0020] S2: The first laser output interacts with the gas to be measured in the heating furnace to generate a second laser with a Raman signal. The second laser in the laser light path contacts the corresponding side reflector, increases the laser power through reflection, and then reflects through the window;

[0021] S3, the Raman signal passes through the window, is received by the signal collection optical path, and then reaches the time-gated Raman spectrometer after collimation;

[0022] S4. The Raman spectrometer obtains the information of the gas to be tested in the combustion furnace through spectroscopic detection.

[0023] As a further description of the above technical solution:

[0024] There are n first laser beams, and 1≤n≤N, N is the number of gas components to be measured, and the wavelengths of the multiple first laser beams cover the molecular absorption spectrum range of the gas components to be measured.

[0025] As a further description of the above technical solution:

[0026] The signal collection optical path includes a lens and a filter arranged on the light entrance side of the time-gated spectrometer.

[0027] As a further description of the above technical solution:

[0028] As stated.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. In the present invention, Raman telemetry technology is used to achieve simultaneous detection of multi-component gases in the combustion furnace, which makes up for the deficiency of absorption spectroscopy technology in detecting homonuclear diatomic molecular gases. An external reflection device is used to generate a Raman signal after the laser light path enters the combustion furnace, and after reflection enhancement, it is transmitted to the time-gated Raman spectrometer. The external reflection device and the time-gated Raman spectrometer can realize remote sensing processing of the gas environment in the reflectivity. The monitoring equipment does not need to be close to the surface of the heating furnace to achieve gas measurement, which is beneficial to avoid damage to the equipment caused by the high temperature of the combustion furnace body.

[0031] 2. In the present invention, a reflection device is added to the equipment to make the laser incident again into the interior of the furnace, interact with the gas in the furnace, excite the gas to generate Raman signals, enhance the signal intensity, increase the effective laser power through reflection, increase the effective interaction power of the laser and gas, and improve the spectral detection sensitivity. At the same time, by using double off-axis parabolic mirrors to collect the signals, the signal collection efficiency is increased compared with the traditional transmission collection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of a detection structure device of a heating furnace combustion gas monitoring device based on laser Raman telemetry technology proposed by the present invention;

[0033] Figure 2This is a system piping principle diagram of a heating furnace combustion gas monitoring method based on laser Raman telemetry technology proposed by the present invention.

[0034] Legend:

[0035] 1. Heating furnace; 2. Reflection device; 3. Time-gated Raman spectrometer; 4. Signal collection optical path; 5. Excitation optical path; 6. Pulsed laser; 7. Control and communication module; 8. Shaping lens group; 9. Off-axis parabolic mirror; 10. Filter; 11. Lens. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] See also Figure 1 and Figure 2 , the present invention provides a technical solution:

[0038] A heating furnace combustion gas monitoring device based on laser Raman telemetry technology includes a pulse laser and a time-gated Raman spectrometer arranged outside the heating furnace, an excitation light path is provided between the pulse laser and the heating furnace, a window is provided on one side of the heating furnace, a reflecting device is provided at the position of the window corresponding to the furnace chamber of the heating furnace, a signal collection light path is provided between the reflecting device and the time-gated spectrometer, and the excitation light path emitted by the pulse laser passes through the window on the side of the furnace chamber of the heating furnace and enters the time-gated spectrometer after being reflected by the reflecting device.

[0039] The reflecting device is a reflecting mirror, which is located outside the heating furnace on the side of the laser light path corresponding to the pulse laser. The combustion gas in the heating furnace is remotely measured through the external reflecting device and the time-gated spectrometer to reduce high-temperature damage.

[0040] The reflector can be connected to the outside of the combustion furnace or a corresponding position on one side of the workshop side wall through a mounting component, and a corresponding heat exchange component can be provided on the outside of the reflector to avoid heat accumulation.

[0041] Moreover, through the designed reflector, the reflector can redirect the laser light into the furnace again, interact with the gas in the furnace, and excite the gas to generate Raman signals to enhance the signal intensity.

[0042] A shaping lens group is installed on the front side of the pulse laser, and the wavelength of the pulse laser covers the molecular absorption spectrum range of the gas component to be measured;

[0043] Among them, the shaping lens group is usually composed of multiple lenses or lens arrays. By precisely designing the shape, position and coordination relationship of each lens, the incident light beam is redistributed and shaped. Its functions include but are not limited to: converting the light beam into a parallel beam, adjusting the divergence angle of the light beam, and controlling the diameter and shape of the light beam.

[0044] Off-axis parabolic mirrors are installed on the corresponding sides of the pulse laser and the time-gated spectrometer, and the pulse laser signal is collected by the double off-axis parabolic mirrors;

[0045] The signal collection optical path includes a lens and a filter provided in sequence on the light incident side of the time-gated spectrometer, and also includes a control and communication module, which controls the pulse laser and the time-gated Raman spectrometer for work control and communication. The control and communication module mainly controls the working parameters of the laser and the time-gated spectrometer.

[0046] The heating furnace combustion gas monitoring method based on laser Raman telemetry technology specifically includes the following steps:

[0047] S1, the pulse laser emits the first laser, which is spot-shaped and beam-expanded by the excitation optical path before reaching the heating furnace;

[0048] S2: The first laser output interacts with the gas to be measured in the heating furnace to generate a second laser with a Raman signal. The second laser in the laser light path contacts the corresponding side reflector, increases the laser power through reflection, and then reflects through the window;

[0049] S3, the Raman signal passes through the window, is received by the signal collection optical path, and then reaches the time-gated Raman spectrometer after collimation;

[0050] S4. The Raman spectrometer obtains the information of the gas to be tested in the combustion furnace through spectroscopic detection.

[0051] There are n first lasers, and 1≤n≤N, N is the number of gas components to be measured, the wavelengths of the multiple first lasers cover the molecular absorption spectrum range of the gas components to be measured, and the signal collection optical path includes a lens and a filter arranged on the light entrance side of the time-gated spectrometer, wherein the gases to be measured include but are not limited to CO, O2, H2O, CO2, H2 and N2, and can be gases from the furnace of a combustion furnace or a connecting pipe.

[0052] In summary, the gas concentration in the combustion furnace can reflect the state of combustion, and accurate monitoring of the gas composition in the furnace is of great significance for promoting efficient combustion. In view of the problems of existing monitoring methods such as complex equipment and difficulty in monitoring multiple gases, the present invention proposes a method and device for monitoring the combustion process of a heating furnace based on laser Raman telemetry technology. The device is composed of key modules such as a pulsed laser, an excitation optical path, a reflection device, a signal collection optical path, a time-gated Raman spectrometer, and a control and communication module. It has the following outstanding advantages: simultaneous detection of multi-component gases in the combustion furnace; avoiding damage to the equipment caused by the high temperature of the combustion furnace body; adding a reflection device to increase the effective power of the laser and gas and improve the spectral detection sensitivity; using a double off-axis parabolic mirror to collect signals and increase the signal collection efficiency. The invention can monitor the multi-component gases in the heating furnace in real time and accurately, provide key parameters for the regulation of low-oxygen combustion and low-carbon emissions in the combustion furnace, and promote the early realization of the goals of the dual-carbon strategy;

[0053] The gas concentration in the furnace can reflect the combustion status. For example, a high concentration of CO may indicate insufficient fuel supply or insufficient combustion temperature, resulting in incomplete combustion of the fuel. A low oxygen concentration may indicate insufficient fuel supply or poor ventilation, resulting in incomplete combustion. A high oxygen concentration may mean excessive fuel supply, which may affect combustion efficiency and energy utilization.

[0054] Raman scattering spectroscopy is an important spectral analysis technique with advantages such as molecular fingerprint characteristics, simultaneous detection of multiple components, no need for sample preparation, and simple equipment. Analyzing the Raman scattering spectrum of a substance can obtain vibrational or rotational information about the molecules, and is widely used in the field of gas composition analysis. Raman spectroscopy is an analytical technique that uses the Raman scattering phenomenon that occurs when light interacts with matter to study the structure, composition, and properties of a sample. When light interacts with matter, most of the light is scattered at the same frequency and energy as the incident light, which is called Rayleigh scattering. However, a small amount of light is scattered at a different frequency and energy, which is Raman scattering. The frequency difference of Raman scattering is equal to the energy difference between the molecular vibrational energy levels corresponding to the vibrational frequencies of the sample molecules. By analyzing the Raman spectrum of a sample, the chemical substances present in the sample, their concentration, structure, and interaction mode can be determined.

[0055] Raman spectroscopy technology has the advantages of simultaneous detection of multiple components, molecular fingerprint characteristics and no need for sample preparation in sample analysis. It is often used for gas composition analysis. Compared with absorption spectroscopy technology, the outstanding advantage of Raman spectroscopy technology is that it can detect homonuclear diatomic molecular gases (H2, N2, etc.); multiple gases can be detected simultaneously using a single light source, and the device structure is simple.

[0056] In the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless expressly limited otherwise. Terms such as "installed," "connected," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0057] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A heating furnace combustion gas monitoring device based on laser Raman telemetry technology, comprising a pulsed laser and a time-gated Raman spectrometer located outside the heating furnace, characterized in that: An excitation light path is provided between the pulse laser and the heating furnace, a window is provided on one side of the heating furnace, a reflecting device is provided at the position of the window corresponding to the furnace chamber of the heating furnace, a signal collection light path is provided between the reflecting device and the time-gated spectrometer, and the excitation light path emitted by the pulse laser passes through the window on the side of the furnace chamber of the heating furnace and enters the time-gated spectrometer after being reflected by the reflecting device.

2. The heating furnace combustion gas monitoring device based on laser Raman telemetry technology according to claim 1 is characterized in that: The reflecting device is a reflecting mirror, which is located outside the heating furnace on the side of the laser light path corresponding to the pulse laser. The combustion gas in the heating furnace is remotely measured through the external reflecting device and the time-gated spectrometer to reduce high-temperature damage.

3. The heating furnace combustion gas monitoring device based on laser Raman telemetry technology according to claim 1 is characterized in that: A shaping lens group is installed on the front side of the pulse laser, and the wavelength of the pulse laser covers the molecular absorption spectrum range of the gas component to be measured.

4. The heating furnace combustion gas monitoring device based on laser Raman telemetry technology according to claim 1 is characterized in that: Off-axis parabolic mirrors are installed on the corresponding sides of the pulse laser and the time-gated spectrometer, and the pulse laser signals are collected by the double off-axis parabolic mirrors.

5. The heating furnace combustion gas monitoring device based on laser Raman telemetry technology according to claim 1 is characterized in that: The signal collection optical path includes a time-gated spectrometer, and a lens and a filter are sequentially arranged on the light incident side.

6. The heating furnace combustion gas monitoring device based on laser Raman telemetry technology according to claim 1 is characterized in that: The utility model also includes a control and communication module, which controls the pulse laser and the time-gated Raman spectrometer to perform work control and communication.

7. A method for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology, applied to a device for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology according to any one of claims 1 to 6, characterized in that: The specific steps include: S1, the pulse laser emits the first laser, which is spot-shaped and beam-expanded by the excitation optical path before reaching the heating furnace; S2: The first laser output interacts with the gas to be measured in the heating furnace to generate a second laser with a Raman signal. The second laser in the laser light path contacts the corresponding side reflector, increases the laser power through reflection, and then reflects through the window; S3, the Raman signal passes through the window, is received by the signal collection optical path, and then reaches the time-gated Raman spectrometer after collimation; S4. The Raman spectrometer obtains the information of the gas to be tested in the combustion furnace through spectroscopic detection.

8. The method for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology according to claim 7, characterized in that: There are n first laser beams, and 1≤n≤N, N is the number of gas components to be measured, and the wavelengths of the multiple first laser beams cover the molecular absorption spectrum range of the gas components to be measured.

9. The method for monitoring combustion gas in a heating furnace based on laser Raman telemetry technology according to claim 7, characterized in that: The signal collection optical path includes a lens and a filter arranged on the light entrance side of the time-gated spectrometer.

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