RU23953U1 - DEVICE FOR SELECTIVE CONTROL OF THE BURNER FLAME - Google Patents

Abstract

1. Device for selective control of the flame of a burner, comprising an optical sensor and an electronic unit, characterized in that it contains one or more channels, each of these channels includes an optical sensor having at least one light filter, which provides emission of radiation from one of the products combustion, and the electronic unit includes a spectrum analyzer tuned to the frequency of the maximum fluctuation of the radiation of this product. 2. The device according to claim 1, characterized in that said filter of each channel provides emission of water or carbon monoxide or carbon dioxide, respectively. The device according to claim 1 or 2, characterized in that it is equipped with a logic device configured to provide a comparison of the values of the signals measured by different channels. A device according to any one of claims 1 to 3, characterized in that the optical sensor of each channel includes at least one narrow-band filter with a maximum transmission in the wings of the spectral line of radiation of the corresponding combustion product.

Description

The utility model relates to the field of monitoring and controlling the operation of heat power devices and is intended to automatically control the presence of flame in any device that burns fuel.

A device for the selective control of a flame of a burner is known, comprising an optical sensor and an electronic unit 1. This technical solution is adopted as the closest analogue.

The disadvantages of the known device installed in a boiler with a large number of burners with one-sided and opposing arrangement include the need to control the operation of each burner, which is associated with the possibility of emergency situations in case of extinction of the flame of one or more burners and the accumulation of excess fuel in the boiler. The complexity of controlling the operation of a single burner by optical methods is associated with the presence of extraneous radiation sources: torches of adjacent burners, boiler walls and elements of heat exchange devices. In addition, the optical characteristics of the burning torch can change with changing burner operating modes.

The technical result obtained by the implementation of this utility model is to ensure the registration of the torch only “of its burner if there are any number of burning torches in the boiler (including when the burners are in the opposite position), at any load of the boiler, when the coefficient of excess air a on a boiler unit within a range of 0.9-1.5, with a change in the degree of recirculation of the combustion products, when different types of burners (solid, liquid and gaseous) are burned in different tiers of burners.

The specified technical result is achieved by the fact that the device

for selective control of a burner flame, comprising an optical sensor and an electronic unit, according to the invention, includes one or more channels, each of these channels includes an optical sensor having at least one light filter that emits radiation from one of the combustion products, and an electronic unit includes a spectrum analyzer tuned to the frequency of the maximum radiation fluctuation of this product.

In addition, the specified filter of each channel provides the emission of radiation, respectively, of water, or carbon monoxide, or carbon dioxide.

In an embodiment, the device is equipped with a logic device configured to provide a comparison of the values of the signals measured by different channels.

The optical sensor of each channel includes at least one narrow-band filter, for example, an interference filter, with a maximum transmission in the wings of the spectral line of radiation of the corresponding combustion product.

According to a utility model, a device for the selective control of a burner flame consists of two components - an optical sensor (OD) and an electronic unit (EB) for processing and analyzing signals.

In FIG. 1 shows a block-functional diagram of the device.

Figure 2 shows the tomogram of the radiation of carbon dioxide in the cross section of the torch.

The block-functional diagram contains an OD, which includes a tube 1 with apertures, a lens 2, a divider 3, capacitors 4 and 5, interference filters 6 and 7, and radiation receivers 8 and 9 and EB, including signal amplifiers 10 and 11, analyzers 12 and 13 of the frequency spectrum, comparison circuits and logic devices 14, output devices 15 interfaces.

Tube 1 with diaphragms serves to protect the optical system

sensor from extraneous light, as well as pollution. Air is blown through the tube 1, creating a small excess pressure inside the tube 1, which prevents the penetration of contaminants into the optical system.

Lens 2 forms an image of torch torches in the plane of the diaphragm of the field where the torch is spatially selected.

The dividing device 3 distributes the luminous flux through two channels.

Using interference filters 6 and 7, spectral selection of the torch is performed.

Capacitors 4 and 5 are intended for concentration of radiation energy at radiation receivers 8 and 9.

Radiation receivers 8 and 9 convert the radiation energy of the torch into an electrical signal, which is amplified by amplifiers 10 and 11.

The analyzers 12 and 13 of the frequency spectrum produce a frequency (time) analysis of the spectrum of the electrical signal and filter out the desired spectral interval.

Comparison schemes and logic devices 14 are used to generate control signals and control signals.

The output devices 15 interface transmit control signals to the control system in the required form.

The system provides for continuous automatic diagnostics of the health of the device for selective monitoring both during the operation of the controlled burner and when it is inoperative

The sensor monitors the operation of the burner by radiation in the selected spectral range using frequency selection of the recorded signal.

carbon - 4.7 microns) or in other parts of the spectrum determined at

debugging the sensor on a specific type of heat power plant. The frequency interval is selected based on experimental data. The use of radiation of water, carbon dioxide and carbon monoxide allows us to determine the local concentrations of combustible and oxidizing elements by the ratio of their intensities.

The sensor observes the selected flame zone using an optical system using a tube, diaphragms, and other devices with minimal use of optical surfaces that can be dirty.

The composition of the combustion products varies along the length of the torch. Some products of combustion exist mainly in the initial zone of the torch. In addition, significant concentration gradients in the initial zone of the plume and a high degree of turbulence lead to a significant difference in the frequency characteristics of radiation in the initial and terminal zones of the plume. The transparency of the torch at different spectral intervals is also different. The task of diagnosing a burning torch is to register the radiation of a selected zone of the torch, in front of and behind which there are emitting and absorbing regions. This problem is solved by the use of spectral and frequency radiation selection. Diagnosis of the initial (root) zone of the torch is carried out by the radiation characteristic of this zone of combustion products or by the ratio of their radiation intensities. The choice of spectral intervals corresponding to the emission of combustion products present in the end zone of the flare makes it possible to exclude the influence of the root zone of the oncoming flare, since the flare becomes opaque due to the considerable optical thickness.

With increasing temperature, the width of the spectral line increases (thermal broadening of the spectral line). Therefore, taking measurements at the edges of the spectral line contour (in the wings

spectral line), high-temperature radiation can be separated

areas from low temperature. The wings of the spectral line correspond to regions in which the radiation (or absorption) intensity is less than half the maximum intensity value. This is important when measuring the radiation intensity of a selected region of the flame through an area containing combustion products. For example, in burners of heat power devices, flue gas recirculation is used to reduce the concentration of nitrogen oxides. Combustion products are fed into the blast air. In this case, the OD line of sight passes through the zone with combustion products. However, since the temperature of these products is significantly lower than the temperature of the same products in the combustion zone, the width of the spectral line is smaller.

The location of the sensor is selected from the operating conditions taking into account heating, ingress of combustion products, etc.

OD is installed on the external wall of the boiler in a pipe passing through the wall of the boiler and providing sight of the burning torch of only one nozzle. Excess pressure in relation to the boiler must be created in the pipe by blowing the pipe with air.

The electronic unit must be located in the control room near the operator's place. The walls of the boiler must have technological windows through which it is possible to use OD measurements to optimize the parameters of the OD and optimize the relative position of the OD and the nozzle.

The burning torch can be divided into three zones: the initial (root) zone, where the thermal decomposition of the initial components of the fuel occurs; the region of maximum temperatures in which a significant part of gaseous and solid products burns out; and the tail region of the torch, in which mixing of the combustion products at a macroscopic level occurs.

The main combustion products have bands of maximum radiation in the infrared region of the spectrum: Н2О - 2.7 microns, СО2 - 4.3 microns, СО - 4.7 microns.

In the initial zone of the plume, intermediate products are formed whose characteristic groups have emission bands in the infrared region. For example, MH2 (2.82-3.12 μm), CN (4.16-4.76 μm), CNO and CNS (4.55-5.27 μm).

The measurements showed that the flame emission spectrum in the fuel-enriched zone has intense lines at wavelengths: 9.37 microns, 6.1 microns, 3.38 microns.

The nitrogen oxides formed in the high-temperature zone have lines at 4.48 μm, 2.87 μm, 5.25 μm, sulfur oxides at 7, 28 μm and 3.98 μm, and CH4-3.32 microns.

Condensed carbon solid particles and coke residues have a continuous emission spectrum with a maximum intensity depending on the temperature and particle size.

Due to high concentration gradients and microscale turbulence, high-frequency radiation pulsations are observed in the initial zone of the plume and in the combustion zone. So, for the micron region where radiation of water molecules predominates in the initial zone of the plume, pulsations are observed at frequencies from 800 to 1500 Hz. In the tail of the plume, pulsations in this region of the spectrum are less than 200 Hz.

The concentration of the main products of combustion of hydrocarbon liquid fuel in% at different values of the coefficient of excess air a are presented in the table.

The table shows that in the root zone of the torch enriched with fuel (small

values a), the concentration ratio differs significantly from this parameter at the end of the flame, where a is of the order of 1.

The proposed device was tested on an experimental burner. The measurements were carried out by a scanning radiometer operating in the visible and infrared regions of the spectrum. The measured spectral range was determined by the type of photodetector. The measurement field was six diameters of the outlet of the burner in the cross section of the jet and eight diameters in the longitudinal. The measurements were carried out from several directions, which made it possible to construct a tomographic image of the distribution of radiation intensities in the cross section of the jet at various distances from the outlet. The processing technique made it possible to take into account the absorption of radiation from combustion products.

To measure radiation in different spectral ranges (by wavelengths), narrow-band interference filters were used, including those corresponding to individual sections of the emission lines of water, carbon monoxide, and carbon dioxide. Additionally, a continuous emission spectrum was measured in the region of 0.4-5.0 μm. As a result of measurements, the following data were obtained. The lines of water, carbon monoxide and carbon dioxide are clearly distinguished in the spectrum of combustion products, which allows measurements to be made in these spectral ranges. Figure 2 shows a tomographic image of the distribution of carbon dioxide radiation (4.3 μm) in the cross section of the flame.

The measurements were performed using an interference filter with a maximum transmission in the left wing of the spectral line. The width of the spectral lines of the main products of combustion with an increase in temperature from 600 to 2000 ° K almost doubles. Product radiation intensity ratios

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combustion for different zones of flares correlate with the values of a in these

areas. The measured frequency spectrum of the plume radiation showed the presence of maximum amplitudes of fluctuations in the radiation intensities characteristic of each flame zone and each combustion product. So for the region from 2 to 3 μm, where water radiation predominates, a characteristic maximum for the root zone of the plume was found in the frequency range from 800 to 1500 Hz, and for the tail region from 50 to 200 Hz.

Using the obtained data, a prototype of the burner flame control device was developed based on the principles stated above, which showed satisfactory test results. Sources of information

1. RU 2121110 C1, 10.27.1998 class. F 23 N 5/08

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Claims (4)

1. Device for selective control of the flame of a burner, comprising an optical sensor and an electronic unit, characterized in that it contains one or more channels, each of these channels includes an optical sensor having at least one light filter, which provides emission of radiation from one of the products combustion, and the electronic unit includes a spectrum analyzer tuned to the frequency of the maximum fluctuation of the radiation of this product.  2. The device according to claim 1, characterized in that the specified filter of each channel provides the emission of radiation, respectively, of water, or carbon monoxide, or carbon dioxide.  3. The device according to p. 1 or 2, characterized in that it is equipped with a logical device configured to provide a comparison of the values of the signals measured by different channels. 4. The device according to any one of claims 1 to 3, characterized in that the optical sensor of each channel includes at least one narrow-band filter with a maximum transmission in the wings of the spectral line of radiation of the corresponding combustion product.