SU1575003A1 - System of automatic control of fuel supply to boiler furnace - Google Patents

Abstract

The invention relates to fuel control systems and makes it possible to increase the stability of the temperature regime of the boiler steam line in variable operating modes. The system automatically adjusts the gain of the regulator when the transmitting properties of the object / boiler change / uses multiplication unit 3, the first input of which is connected to the output of comparison unit 4, and output to the input of regulating unit 2. Multiplication unit 3 here operates in an inertia-free mode with varying gain, the value of which is proportional to the signal at its second input. At that, the value inverse to the current gain / transfer / object / boiler / factor can be determined in pressure block 9 by dividing two signals: the output signal of the regulating unit 2, which determines the frequency of rotation of the electric motors of the fuel supply units, and the output signal of the adder 10, which is equal to signal, ie the sum of the main and speed signals. The main signal is either steam temperature at the output of the primary path or a heat signal, and the speed signal is either a signal for flue gas temperature, or a signal for water temperature in the lower radiation part of the boiler steam path, or a flame signal . 1 il.

Description

The invention relates to a power system, namely to the regulation of thermal processes in a power unit.

The aim of the invention is to increase the stability of the temperature mode of the steam duct of the boiler in variable operating modes.

The drawing shows a structural diagram of the system of automatic control of fuel supply.

The system contains the stations 1 for controlling the frequency of rotation of the electric motors of the fuel-feeding devices, the regulating unit 2, the multiplication unit 3, the comparison unit 4, the driver 5, the main signal sensor 6, the speed signal sensor 7, the differentiation unit 8, the division unit 9 and the adder 10.

The system works as follows.

In the steady state, when there are no fire disturbances and the speed signal (the signal at the output of differentiation unit 8) is zero, the signal at the output of the adder 10 is equal to the main signal, i.e. sensor 6 output signal. This signal in the comparison block 4 fully compensates the master signal equal to the specified value of the main signal and output from the driver 5. In this mode, the signal input to the first input of the multiplication unit 3 is zero, the output signal of the block 3 the multiplication that arrives at the input of regulating unit 2 is also zero. In this case, the electric motors of the fuel-feeding devices rotate with a constant rotation frequency determined by the output signal of the regulating unit 2, which is fed to the inputs of the stations 1 that control the frequency of rotation of these electric motors.

Occurrence of furnace disturbances (for example, deterioration of fuel quality), reduction of feed water temperature, etc. leads to a decrease

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of the regulated signal (i.e., the speed signal first appears, and then the main signal decreases), which, with the same output of the regulating unit 2, causes a decrease in the object’s transmission coefficient and, consequently, an increase in the output signal of the dividing unit 9, leading to increase the gain of the regulator.

Since a deviation signal appears at the output of the comparator unit 4, which, after amplification in multiplication unit 3, enters the input of the regulating unit 2, the latter begins to increase its output signal, thereby increasing the frequency of rotation of the electric motors of the fuel supply units, leading to an increase in the amount of fuel fed to the furnace.

Since, as the amount of fuel introduced into the furnace increases, the control value deviation decreases, i.e. the increase in the regulated value to the previous level, the output signal of the dividing unit 9, determining the controller gain factor, in this mode will remain approximately constant corresponding to the new coefficient value transferred to the object.

The main signal is either the vapor temperature at the output of the primary path (usually before the first injection), or the heat signal, formed by summing up the steam flow rate and rate of change in vapor pressure, used to indirectly estimate heat generation in the furnace.

As a high-speed (advance) signal, which enters the regulator through the differentiator, they use either a flue gas temperature signal, or a water signal signal in the lower radiation section of the boiler steam path, or a torch radiation signal.

Thus, in the proposed fuel controller, the presence in the control channel of two elements with mutually inverse characteristics (the object and the multiplication unit) ensures the stability of the gain factor of this channel, which makes it possible to stabilize the control quality when the characteristics of the object change.

Claims (1)

Invention Formula The system of automatic control of the fuel supply to the boiler furnace containing sensors of the main and speed signals, the last of which is connected to a differential, block dividing and serially connected setting unit, comparison unit, multiplication unit, regulating unit and rotational speed control stations of electric motors of fuel supply devices; the output of the regulating unit is connected to the first input of the division unit whose output is connected to the unit multiplying, in order to increase the stability of the temperature regime of the boiler steam line in variable operating modes, the system additionally holds the adder, to the inputs of which the sensor of the main signal and the differentiator are connected, l to the outputs - the blocks of division and comparison.