RU2115865C1 - Burner flame control device - Google Patents

Abstract

FIELD: power generating and industrial steam generators and other low power fire plants combusting different kind fuels. SUBSTANCE: device has two photoelectric transducers 1 and 2 with similar spectral response characteristics in region of 2.0 - 3.5 μm with maximum of 3.0 μm corresponding to maximum absorption of optical signal by fuel combustion products. Two channel electrical circuit with identical channels 3 and 4 for processing optical signals passed to transducers 1,2, respectively, is connected to outputs of transducers 1 and 2. Device has adder 5 and control arrangement 10 connected to output of adder 5. Transducers 1,2 are installed in sight channels of opposite burners and oriented along their common axis to root zones of flame tongues. Electrical schemes of both channels 3,4 are identical. At normal operation of both burners, resultant signal passing from output of adder 5 to control arrangement 10 is zero. In case of vanishing of flame in one of burners, resultant signal differs from zero, and its polarity indicates defective burners. EFFECT: improved reliability of selective control of burner flame by tuning away from false signals. 1 dwg

Description

 The invention relates to the field of automatic control of the presence of a flame in the combustion chamber of a fire-fighting installation equipped with oncoming burners and can be used to control the operation of the corresponding energy and industrial steam generators, as well as any other fire-fighting installations burning various types of fuel.

 Selective control of the flame of each burner is necessary to prevent accidents related to the possibility of an explosion or overflow of the combustion chamber with unburned fuel. The problem of such control is associated with the possibility of false signals passing about the presence of flame from neighboring burners and the red-hot walls of the combustion chamber, as well as the absence of a flame in case of a malfunction of the control system.

 Closest to the invention is a burner flame monitoring device comprising two photoelectric sensors with the same spectral characteristics, a two-channel electrical circuit for processing optical signals received by the sensors, an adder with two inputs connected respectively to the outputs of the first and second channels, and a control device connected to the output of the adder . In this device, photoelectric sensors are oriented to the same flame zone of one burner not parallel to its axis at different angles. During normal operation of the burner (flame), the difference in the amplitude of the signals at the output of the adder is zero. It is assumed that when the flame goes out, sensors oriented at different angles will receive radiation from different temperature zones of the furnace, which will lead to the appearance of a signal at the output of the adder that is non-zero, causing the control device to trip.

 However, it is possible that in case of flame extinction, the spatial zones of the furnace, sighted by the sensors, can have close temperatures, which will lead to a false response of the control device. Provided in the prototype of the measures for this case significantly complicate the electrical circuit of the device, which can adversely affect the reliability of its operation. In addition, the orientation of the sensors not on the axis of the burner causes difficulties in constructive implementation, requiring the organization of emergency passes in the boiler lining.

 The result of the invention is improving the reliability of selective flame control by improving the detuning from false signals.

 To achieve this result, in a burner flame control device containing two photoelectric sensors with the same spectral characteristics, a two-channel electrical circuit for processing optical signals received by the sensors, an adder with two inputs connected respectively to the outputs of the first and second channels, and a control device connected to the output of the adder , according to the invention, the sensors are installed in opposite burners along their common axis, each oriented to the root zone flame torch of the corresponding burner, and the spectral characteristic of the sensors is selected in the range of 2.0 - 3.5 microns.

 The drawing shows a schematic diagram of a device according to the invention.

 The device contains two photoelectric sensors 1 and 2 with the same spectral characteristics in the region of 2.0 - 3.5 μm with a maximum of 3.0 μm, corresponding to the maximum absorption of the optical signal by the products of fuel combustion. In particular, a photoresistor with an optical filter in the above range can be used as each of the photoelectric sensors. To the outputs of sensors 1 and 2, a two-channel electrical circuit is connected with identical channels 3 and 4 of the processing of optical signals arriving to sensors 1 and 2, respectively. The device also contains an adder 5 with inputs 6 and 7, respectively connected to the outputs 8 and 9 of channels 3 and 4, and a control device (UU) 10 connected to the output of the adder 5. Sensors 1 and 2 are installed in the inspection channels of the opposite burners (not shown) not shown) and are oriented along their common axis to the root zones of the flame torches of the respective burners. The electrical circuit of both channels 3.4 is made identically and contains serially connected pre-amplifier 11 coming from sensors 1, 2 of electrical signals, a high-pass filter (HPF) 12, an amplitude detector (HELL) 13, an adjustable amplifier (RU) 14 of the sensitivity of photoelectric sensors 1 , 2 and a smoothing filter (SF) 15. An additional electric circuit 16 for isolating the self-diagnosis signal from the light emission generator 17 with a frequency of 2 kHz connected to the emitting LED 18 is connected to the outputs of the RU 14. holds tuned band-pass filters (PF) 19, logic device (LU) 20 "OR" and threshold device (LI) 21. The level of the diagnostic signal is selected so that it is about 10 times less than the level of the working signal.

 The operation of the proposed flame control device is based on the principle of emitting pulsations of the brightness of the flame during combustion of fuel, which allows you to tune out the radiation from the walls of the furnace, which does not have pulsations, as well as from the radiation of neighboring and oncoming burners by selecting the spectral characteristics of the sensors and the frequency bandwidth of the two-channel electric tract.

 The device operates as follows.

 The electrical signals generated by sensors 1 and 2 from the root of the torches of the oncoming burners are fed through the corresponding channels 3.4 to the amplifiers 11, then to the high-pass filter 12, where the amplitude-frequency characteristic is formed, limited from below by a frequency of 300 Hz. This frequency is determined on the basis of reliably suppressing a signal that can penetrate into the field of view of sensors 1 and 2, caused by fluctuations in the edges of the flame of adjacent burners with a frequency of less than 100 Hz. Next, the signals are fed to HELL 13, where, by diode detection, useful signals of flame pulsations arriving at the RU 14 are extracted from the common signal, with which the sensitivity of sensors 1 and 2 is regulated under conditions of reliable operation of the SU 10. From the RU 14, the signals arrive at SF 15, and from there to the inputs 6 and 7 of the adder 5, at the output of which their difference is formed. During normal operation of both burners, the resulting signal entering the control unit 10 from the output of the adder 5 is equal to zero. In the event of the extinction of the flame of one of the burners, the resulting signal becomes nonzero, and its polarity makes it possible to identify a faulty burner. To implement such a program, UU 10 can be equipped with a threshold device of three levels. When one of the two emergency levels of the threshold device is triggered, the UU 10 turns on the alarm or the automatic shutdown of the fuel supply to the corresponding burner (not shown in the drawing). In SF 15 of each channel 3.4, by changing the constant time of the charge and discharge of the capacitance, the delay time of the operation and release of the output relay (not shown) of the UU 10 is adjusted in accordance with the requirements of the technical operation of a particular fire-fighting installation. The output of the RU 14 is also taken self-diagnosis signals received in the channels 3.4 from the LED 2. These signals are extracted from the useful signals using PF 19 and processed in the LU 20, the resulting signal from which is fed to the PU 21, including an alarm (not shown shown) about a malfunction in the control circuits. An additional function of the SF 15 is to prevent the self-diagnosis signal from passing through the control unit 10.

 The selectivity of the control of the proposed device is due to the choice of the spectral characteristic of the sensors 1,2, corresponding to the maximum absorption of the optical signal by the products of fuel combustion, the principle of emitting flame pulsations and the use of the high-pass filter 12. The absorption of the optical signal by the products of combustion eliminates the formation of a false signal about one of the burners the presence of radiation from the flame of the opposite burner; the allocation of pulsations of the flame eliminates the effects of optical radiation from the heated walls of the furnace; HPF 12 eliminates the formation of a false signal from the radiation of the edges of the torches of adjacent burners.

 If it is necessary to introduce the operation of UU 10 when both counter-burners are extinguished, the adder 5 can be configured to issue two resulting signals - differential and summing. In this case, the difference signal will still give information about the extinction of the torch of one of the burners, and the summing one will give information about the extinction of the torch of both burners (by the absence of the resulting signal). Difference and summing signals can be supplied to UU 10 using two threshold devices (not shown in the drawing).

 This device in particular can be recommended for low power boilers equipped with oncoming burners, where the choice of the integrated optical radiation of the furnace space as a reference signal is not reliable due to the noticeable dependence of the intensity of this radiation on the operation of each burner.

Claims (1)

 A flame control device for a burner of a fire-fighting installation containing two photoelectric sensors with the same spectral characteristics, a two-channel electrical circuit for processing optical signals received by the sensors, an adder with two inputs connected respectively to the outputs of the first and second channels, and a control device connected to the output of the adder, characterized in that in relation to a fire-fighting installation equipped with counter-mounted burners, sensors are installed in these rods along their common axis, each oriented to the root zone of the flame of the corresponding burner, and the spectral characteristic of the sensors is selected in the region of 2.0 - 3.5 microns.