SU1490379A2 - Method of automatic control for straight-through boiler - Google Patents

Abstract

The invention relates to the automation of continuous steam generators and allows for greater control accuracy over a wide range of loads. In the established boiler operation mode, the signal of the setting device 6 is compensated by the signal of the water flow sensor 5 at the input of the differentiator 4 and the signal of the root extractor 15 at the input of the regulator 7. The signal of the temperature sensor 3 is compensated by the static setting of the power regulator 1, therefore the controller is balanced. In the process of operation, as the water pressure in front of the boiler approaches the new value, the signal of the differentiator 14 decreases, and the signals of the adders 11 and 12, as well as the multiplier 13, increase. At the same time, the signal of block 13 increases faster than the signal of differentiator 14 decreases in the upper part of the load range, and slower in the lower part of the range, and the signal of the root extractor 15 increases at a rate close to the decrease rate of the signal of differentiator 14 over the entire load range. Thus, unit 15 linearizes the dependence of the static component of the parameter characterizing heat generation in the furnace from the boiler load, as a result of which the control accuracy is improved. 1 il.

Description

The invention relates to automatic regulation, in particular to the automation of direct-flow steam generators, and is an improvement of the avtoSV technical solution. No. 1325248.

The purpose of the invention is to improve the accuracy of regulation in a wide range of loads.

The drawing shows the scheme of implementation of the method

The boiler power regulator 1 acts on the control valve 2 and receives signals from the sensor 3 of the medium temperature at the intermediate point of the boiler path and from the differentiator 4, to the inputs of which the water flow sensor 5 and the boiler setpoint 6 are connected. Unit 6 is also connected to the controller 7 of the fuel, which acts on the valve 8, which regulates the flow of fuel. Sensors 9 and 10 of the vapor pressure behind the boiler and feedwater are connected to the inputs of the adders 11 and 12. The inputs of the adders 11 and 12 are connected to the input of the multiplication unit 13. The water pressure sensor 10 in front of the boiler is connected to the second inputs of the combiners I and 12, as well as to the input of the differentiator 14, the output of which is connected to the third vertical input of the fuel regulator 7. The output of the multiplication unit 13 is connected to the input of the root extraction unit 15, and the output of the unit 15 is connected to the second inverting input of the regulator 7 ,,

Automatic regulation of the flow boiler is as follows.

In steady state operation j; the boiler setpoint 6 signal is compensated by the signal of the water flow sensor 3 at the input of the differentiator 4 and the root extractor 15 signal at the input of the controller 7. The temperature sensor 3 signal is compensated for by the static setting of the power regulator 1, and therefore the controller 1 is in balance.

The signal of the differentiator 14 is zero, since the water pressure in front of the boiler does not vary with time. Therefore, the sum of the signals at the input of the regulator 7 is zero and the regulator 7 is also in the state of balance.

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To increase the load of the boiler, affect the setting unit 6 load. The increment of the setpoint signal 6 violates the compensation of the signals at the input of the differentiator 4, which transmits a signal of the unbalance to the input of the power supply controller 1. The regulator 1 influences the opening of the valve 2 until the water flow increases so much that by increasing the signal of the sensor 5 the increment of the setpoint signal 6 is compensated. At the same time, the increment of the setpoint signal 6 disrupts the balance of the fuel regulator 7, which causes the regulator 7 opening the valve 8, which increases the fuel consumption and, consequently, the heat gap in the furnace. With an increase in heat generation, the signal of differentiator 14 increases. When the increment of this signal reaches the value of the signal increment of the setting device 6, the controller 7 will stop increasing the fuel supply. The required ratio of changes in the flow rates of water and fuel is achieved by adjusting the controller by selecting the transfer coefficient and differentiation time of differentiator 14, therefore the temperature of the medium at the intermediate point of the boiler path, measured by sensor 3, does not change and controller 1 remains in balance. the water pressure in front of the boiler to the new steady-state value of the signal of the differentiator 14 decreases, and the signals of the adders II and 12, as well as the multiplication unit 13, increase. At the same time, the signal of block 13 increases faster than the signal of differentiator 14 decreases, in the upper part of the load range and slower in the lower part of the range, and the signal of the root extractor 15 increases at a rate close to the decrease rate of the signal of differentiator 14 over the entire load range. As a result, the sum of the signals of the differentiator 14 and the block 15 remains approximately constant throughout the transition process, and the controller 7 maintains a constant fuel consumption corresponding to the required ratio of water and fuel consumption until the end of the transition process. Thus, the root extraction unit 15 linearizes the dependence of the static component of the parameter characterizing heat generation in the firebox on the boiler load.

In the same way as described above, the control process proceeds with a decrease in the boiler load.

In this case, the signal of unit 15 maintains a constant scale of heat generation, and the scale of the signal of multiplication unit 13 decreases with decreasing load and reaches a minimum at the lower limit of the load range.

Claims (1)

Invention Formula The method of automatic regulation of the flow boiler on the auth. No. 1325248, characterized in that, in order to increase the control accuracy over a wide load range, additionally, before adding the product, the difference of the measured pressures by their sum with the rate of change of water pressure in front of the boiler, takes the square root from the product of the pressure difference of water before the boiler and the vapor pressure behind the boiler for the sum of these pressures.