JPH046313A - Air supplying device for boiler - Google Patents

Abstract

PURPOSE:To enable the optimum amount of air to be always supplied with a simple configuration of equipment by a method wherein an air supplying device is provided with an air supplying amount in response to each of detected values of a fuel flow rate sensing means, an air flow rate sensing means, an oxygen concentration sensing means and a smoke concentration sensing means. CONSTITUTION:Each of flow rates of residue gas, mixed gas, cold oil, hot oil and air supplied to a boiler 1 is detected through transmittors 21, 25 or 27, 41 and 49 as an electrical current signal and inputted to an air flow rate control means 88. The air flow rate control means 88 at first calculates a theoretical air amount in response to these detected values. A correcting calculation for a predetermined air ration is carried out in response to the detected values of O2 concentration meter 17 and a smoke concentration motor 19. The corrected air ratio is multiplied by the theoretical air volume to obtain a target air amount SP and this is set to a control throttle 97. The control throttle 97 may output an electrical current signal corresponding to a difference OV between the target air volume SP and a supplied air flow rate PV to an electro- air convertor 91.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an air supply device for a boiler that optimally controls and supplies the amount of air for fuel combustion to a boiler to improve combustion efficiency and reduce NOx. .

[Prior Art] FIG. 2 is a schematic diagram showing the configuration of a boiler air supply control device according to a conventional example. In the figure, 1 is a boiler, and 3 is a transmitter that outputs air pressure corresponding to the flow rate of residual gas and butane gas supplied to the boiler 1.Based on each output pressure, the air pressure corresponding to the theoretical air amount commensurate with the fuel is calculated. A pneumatic calculator 5 outputs an air pressure that corresponds to the theoretical air amount by manually inputting the air pressure output by the calculator 3 and the air pressure corresponding to the flow rate of cold oil supplied to the boiler 1. A formula calculator 7 is a pneumatic calculator which manually inputs the air pressure from the calculator 5 and the air pressure according to the flow rate of hot oil supplied to the boiler 1, and outputs the air pressure corresponding to the theoretical air amount commensurate with them. , 9 is a pneumatic calculator that corrects and outputs the air pressure corresponding to the theoretical air amount input from the calculator 7 according to fluctuations in the master pressure of the boiler 1; 11 is a pneumatic calculator that outputs the air pressure corresponding to the theoretical air amount input from the calculator 7; An air amount regulator 13 manually adjusts the air pressure according to the supplied air flow rate and outputs an air pressure corresponding to the difference between the two. Reference numeral 13 manually multiplies the output pressure from the air amount regulator 11 by a desired coefficient (air ratio). 15 is a fan that supplies air to the boiler 1 while increasing or decreasing the supply amount according to the air pressure from ratio 13;
17 is a 0° concentration meter for measuring the oxygen concentration in the exhaust gas of the boiler 1, and 19 is a soot concentration meter for measuring the concentration of smoke in the exhaust gas of the boiler 1.

When the air pressure corresponding to the amount of residual gas, butane gas, and cold oil supplied to the boiler 1 is manually input to the calculator 3, 5.7,
Air pressure corresponding to the theoretical air amount suitable for burning each fuel is generated by each computing unit and added sequentially to the computing unit 7.
pressure from Then, this is further corrected via the computing unit 9 and the air amount regulator 1 in accordance with the mask pressure of the boiler and the air flow rate being supplied, and is output to the ratio 13.

This air pressure is roughly multiplied by the air ratio at ratio 13, and the amount of air supplied by the fan 15 is adjusted according to this pressure, but the air ratio at ratio 13 is set by the operator. ? This is done manually by looking at the a degree meter 17 or by directly observing the exhaust gas.

On the other hand, instead of this operator, CO. CO2
There is also known a device that analyzes the air pressure and 02 and reflects the results in the air supply amount.

[Question to be solved by the invention] However, according to the prior art shown in Fig. 2, feedback of the combustion result to the air supply amount is performed manually based on the judgment of the operator, so delicate control is not possible. However, the variation is large, and variations in the boiler load may result in excess air or incomplete combustion. Also, since the ratio is usually set so as not to emit soot, excessive air is inevitably produced. In addition, each computing unit has a rough G value scale, so calculations are not accurate, and since it is a pneumatic type, the calculation speed and adjustment speed are slow.

Furthermore, there is a problem in that the device that reflects the above-mentioned exhaust gas analysis results is very expensive.

In view of the problems of the prior art, an object of the present invention is to
To provide an air supply device for a boiler that can always supply an optimum amount of air with a simple equipment configuration.

[Means for Solving the Problems] In order to achieve the above object, the boiler air supply device of the present invention includes a fuel flow rate detection means for detecting the flow rate of fuel supplied to the boiler, and a fuel combustion air supply device for supplying fuel combustion air to the boiler. an air supply means; an air flow rate detection means for detecting the flow rate of fuel combustion air supplied to the boiler by the air supply means;
An oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas of the boiler, a soot concentration detection means for detecting the soot concentration in the boiler exhaust gas, a fuel flow rate detection means, an air flow rate detection means, an oxygen concentration detection means, and the soot concentration It is equipped with an air co-supply amount control means for controlling the air supply means, which controls the air supply amount based on each detection value of the detection means.

The fuel flow rate detection means usually detects the flow rate of fuel supplied to the boiler as an electric signal, and the air flow rate detection means detects the flow rate of combustion air supplied to the boiler as an electric signal.

optimally controlled.

[Operation] In this configuration, the flow rate of fuel supplied to the boiler is detected as an electrical signal via a transmitter, a pneumatic converter, etc., and the air supply amount control means, for example, burns the fuel based on the detected value. A computer or the like can be used to determine the theoretical amount of air that is sufficient or insufficient to cause the problem. However, normally, a larger amount of air is required than this theoretical value, and the value obtained by multiplying this theoretical value by a predetermined coefficient (air ratio) is set as the target air amount. Base corrections are added. That is, if the 02 concentration is high, the target air volume is set to be small, and if the soot and smoke density is high, the target air volume is set to be larger. The air supply amount control means controls the air supply means so that the difference between the thus set target value and the currently supplied air amount becomes small.

Therefore, the amount of air to be supplied is always adjusted to be sufficient or insufficient under the monitoring of the 02 concentration in the exhaust gas and the soot concentration. [Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an air supply device according to an embodiment of the present invention. In the figure, the same elements as in FIG. 2 are given the same reference numerals.

In the computing unit 3, a transmitter 21 is connected to a transmission line 23, which outputs air pressure according to the flow rate of register gas supplied to the boiler 1.
Oscillators 25 and 27, which output air pressure according to the flow rate of the mixed gas supplied to the boiler 1, are connected to the other input end via a transmission line 29. The oscillator 25° 27 and the transmission line 29 are connected to each other by a range switching cock 31, so that the oscillator 25
The measurement range can be switched by selecting and using one of the ranges 1 and 27. In addition, a switching cock 33 is provided in the middle of the transmission line 29 for when mixed gas is used and for extinguishing, and the pressure is 0.2 kg/cm.
2 air sources are connected, and when extinguishing a mixed gas, the pressure in the transmission line 29 is reduced to 0.2 by operating the switching cock 33.
kg/Cm2 (corresponding to the mixed gas supply flow rate of zero).

On the other hand, the transmission line 35 from the computing unit 3 to the computing unit 5 is provided with a switch cock 37 for switching between use of residual gas and extinguishing, and a transmission line 39 branched from the transmission line 29 is connected to this, and the switching cock 37 is connected to the switching cock 37 for switching between use of residual gas and extinguishing. By operating the cock 37, the pressure in the transmission line 29 is directly input to the calculator 5 without being input from the calculator 3. A transmitter 41 that outputs air pressure corresponding to the flow rate of cold oil supplied to the boiler 1 is connected to a transmission line 43 at the other input end of the calculator 5.
The transmission line 43 is provided with a switching cock 45 having the same function as the cock 33 and connected to a 0.2 kg/cm 2 air source. The output of the calculator 5 is input to the calculator 7 via a transmission line 47, and an oscillator 49 that outputs air pressure corresponding to the flow rate of hot oil supplied to the boiler 1 is transmitted to the other input terminal. Road 51
0.2 kg/cm' to the transmission line 51.
A switching cock 53 having the same function as the cock 33 is provided, which is connected to an air source. The output of the calculator 7 is input to the calculator 9 via the transmission line 55, and
A transmitter 57 that outputs the master pressure of the boiler 1 is connected to the other input terminal. Calculator 9 for air volume regulator 1
The output is input manually via a transmission line 59, and a transmitter 61 that outputs air pressure corresponding to the air flow rate supplied to the boiler 1 is connected to the other input end via a transmission line 63.

The above configuration corresponds to the configuration of the similar part in FIG. 2 according to the conventional example, and the theoretical air amount corresponding to each fuel is are calculated and summed up, the calculation unit 9 makes a correction according to the pressure fluctuation of the boiler 1, and the air amount regulator 11
Air pressure corresponding to the difference between the corrected target air amount and the currently supplied air amount is output to the fan via the transmission line 65. As the output destination, either the transmission line 69 or the transmission line 71 connected to the transmission line 65 is selected by the switching circuit, and if the transmission line 69 (home output) is selected, The rotational speed of the fan is controlled according to the pressure, and when transmission line 71 (bend damper output) is selected, the valve at the inlet of the fan, which rotates at a constant rate, is controlled to open and close. Further, in either of the transmission lines 69 and 71, the pressure can be switched to a manually adjustable pressure from an air source using a changeover switch 73 or 74.

Next, the configuration of the parts related to the present invention will be explained.

In FIG. 1, 76-80 are transmission lines 82-8, respectively.
Each transmission line 82 is a pneumatic converter connected to the transmission lines 23,29,4351 and 63 via -86 pressure is converted to a corresponding current in the range of 4-20 mA and output. 88 are these current values and O
2 air supply amount control means that outputs a current in the range of 4 to 20 mA corresponding to the difference between the target air amount to be supplied and the current air supply flow rate based on the detected values of the concentration meter 17 and the soot concentration meter 19; It is. 91 indicates this output current value as the corresponding 0
It is an electro-pneumatic converter that converts into air pressure in the range of 2 to 1.0 kg/Cm2 and outputs it, and its output is connected to the transmission line 65 by a switching cock 95 via a transmission line 93.

That is, the output to the fan can be selected from either the output of the electro-pneumatic converter 91 or the output to the air amount regulator 11 by operating the switching cock 95.

The air supply amount control means 88 controls current signals output from the pneumatic converters 76 to 79 and the 02 concentration meter 17 and the smoke concentration meter 1.
9 into digital data, a computer that performs predetermined calculations based on this digital data, and a current air supply flow rate PV that is set based on the target air tsp and the output of the pneumatic converter 80. There is a control slot 97 that outputs a current signal in the range of 4 to 20 mA corresponding to the difference OV. It also has an operator station where the target air amount SP can be set manually.

In this configuration, the flow rates of resist gas, mixed gas, cold oil, hot oil and air supplied to the boiler 1 are controlled by transmitters 21, 25 or 27, respectively.
41.49 and 61, transmission lines 82 to 86, and pneumatic converters 76 to 80, it is detected as a current No. 48 of 4 to 20 mA, and is manually inputted to air flow rate control means 88.

Then, the air flow rate control means 88 first calculates the theoretical air amount based on these detected values. The theoretical air amount is determined by calculating the theoretical air amount for each fuel and summing these values. Next, a correction calculation is performed for a predetermined air ratio based on the detected values of the 02 densitometer 17 and the soot densitometer 19, and the thus corrected air ratio is multiplied by the theoretical air amount to set the target air amount SP. Set in control slot 97. On the other hand, the control slot 97 is set with the current air supply amount PV detected via the pneumatic converter 80, and the control slot 97 is set with a current signal corresponding to the difference OV between the target air amount SP and the air supply flow rate pv. is output to the electro-pneumatic converter 91.

However, if this difference O■ is excessive, an alarm message is displayed on the operator station etc. to prompt the operator to check the situation, and the previous output is maintained until the message is confirmed.

The above processing in the air control means 88 is continuously performed at a predetermined timing so as to always ensure the optimum air flow rate for each fuel flow rate variation.

Here, when the operator station switches to manual mode, the control according to the above sequence is put into a hold state, but when the mode is set to auto mode, the automatic mode is instantaneously set, and the above sequence control is restarted. However, when returning to auto mode, an air ratio calculation is performed to prevent the output from fluctuating, and a target air amount is set based on this calculation.

If the fuel flow rate current signal suddenly changes, a rate of change alarm is activated, sequence control is stopped, and the system enters manual mode. Moreover, when this current signal becomes below the lower limit setting value, an alarm message is pressed.

[Effects of the Invention] As explained above, according to the present invention, in addition to the supplied fuel flow rate, the oxygen concentration and soot concentration in the exhaust gas are detected, and the air supply is performed taking these into consideration. Since we controlled the amount of
A simple configuration can supply just the right amount of air. Furthermore, since the fuel supply flow rate and the like are converted into electrical signals and processed, it is possible to control the air supply amount with greater precision and responsiveness.

Total, 19° smoke density meter, 21,25.2741,
49. 57. 61 + speech device,
76-8o: Pneumatic converter, 88: Air supply amount control means.

Claims (2)

[Claims] (1) A fuel flow rate detection means for detecting the flow rate of fuel supplied to the boiler, an air supply means for supplying air for fuel combustion to the boiler, and a flow rate of the fuel combustion air supplied to the boiler by the air supply means. an air flow rate detection means for detecting the oxygen concentration in the boiler exhaust gas; an oxygen concentration detection means for detecting the oxygen concentration in the boiler exhaust gas; a soot concentration detection means for detecting the soot concentration in the boiler exhaust gas; a fuel flow rate detection means; an air flow rate detection means 1. An air supply device for a boiler, comprising: air supply amount control means for controlling the air supply means to control the air supply amount based on each detection value of the oxygen concentration detection means and the soot concentration detection means. (2) The fuel flow rate detection means detects the flow rate of fuel supplied to the boiler as an electrical signal, and the air flow rate detection means detects the flow rate of combustion air supplied to the boiler as an electrical signal. The air supply device for a boiler according to claim 1.