SU1288432A1 - Method for automatic control of contact waste heat recovery unit operation - Google Patents

Abstract

The invention relates to a power system and allows an increase in the degree of utilization of the heat of combustion products. The heat utilizer with a closed circulation circuit of the intermediate heat carrier contains a surface heat exchanger 5 with a circulation circuit of a heated medium, a pump 4 and a flow regulator 6. The regulation of the utilizer is made by changing the flow rate of the intermediate coolant depending on the parameter indirectly characterizing the degree of utilization. In quality of this. the parameter uses the temperature difference (St) of the intermediate heat transfer medium at the exit of the heat exchanger, measured by the sensor 7, and the heated medium at its input, measured by the sensor 9. The signal (81) is compared in the adder 14 with the converted signal (oj) received from the medium temperature sensor 10 after the heat exchanger. 1 il. (L to the consumer m p n p - From the village №O

Description

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The invention relates to a power system and can be used to control the operation of contact heat exchangers of the flue combustion products with an intermediate heat carrier in a boiler room and thermal power plants.

The aim of the invention is to increase the degree of heat utilization of combustion products.

The drawing shows the installation diagram that implements the proposed method.

The installation contains a boiler 1 with a closed circulation circuit of a high-temperature heat carrier e which includes parallel reheating heat exchanger 2 and heat consumers (not shown). The tract of waste combustion products of the boiler 1 is switched on a contact heat exchanger 3 of heat with a closed circulation circuit of intermediate heat carrier j containing a pump 4, an intermediate heat exchanger 5 and a flow regulator 6. A temperature sensor 7 is installed in the circulation circuit of the intermediate heat transfer medium after the intermediate heat exchanger 5. The heated water path includes an intermediate heat exchanger 5, a preheat heat exchanger 2, and 8 hot water consumers. In the path of the heated water to the intermediate heat exchanger 5, a temperature sensor 9 is installed, after the heat exchanger 35 a temperature sensor 10 is installed. The automatic control system contains an adder 11, to which the control device 12 is connected and, through the amplifier 13, a temperature sensor 10. The output of the adder 11 is connected to the direct input of the adder 14, to the second inverse input of which sensors 7 and 9 are connected, differentially connected. Summatr 14 through the amplifier 15 is connected to the flow regulator 6.

The method is implemented as follows.

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In boiler 1, heat is generated during combustion of fuel to consumers. Combustion products leaving boiler 1 with a temperature of 150 ° C enter heat contact heat exchanger 3, from where they are removed from a smoke exhaust system to a chimney with a temperature of 25-45 ° C. Heated in contact utilizer 3 warmth-to-temp5

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Celsies ZZ-ZO C intermediate heat transfer fluid is collected in the pallet of contact heat exchanger 3, from where it is pumped to pump 4 to intermediate heat exchanger 5 and returned to heat contact heat exchanger 3 with a temperature of 19-36 ° C. Water from the water supply system with a temperature of 16-21 C enters the intermediate heat exchanger 5, where it is heated to 31- 44 C, into the heat exchanger 2 reheating, where it is heated to 65 ° C with hot water from boiler 1, and then consumers 8 hot water.

The operation of the contact heat exchanger 3 of the heat is controlled as follows.

The signal (o ,,) received from the sensor 10. Water temperature after the intermediate heat exchanger 3, is amplified (b) in the amplifier 13, is fed to the input of the adder 11 and algebraically summed in it with a constant value signal (a) from the setpoint 1-2 . The output of the adder 11 .signal (a + bllg) goes to one of the inputs of the adder 14 and is compared in it with the signal (St) received from the differentially connected temperature sensors 7 and 9 and corresponding to the actual difference between the temperature of the intermediate heat exchanger at the output of the intermediate heat exchanger 5 and the temperature of the heated water at the entrance to it.

In the optimal mode, the mismatch of these signals is absent. one

Since one signal goes to the direct and the other to the inverted input of the adder 14, then at the output of the adder 14 there is a signal in, this case is equal to zero.

In case of a change in the flow rate of the heated water, the values of St and C change, a mismatch of the signals (a + b t) and (8t) occurs, and a regulating signal of the corresponding polarity is formed at the output of the sum MciTopa 14. which is amplified by amplifier 15 and fed to an actuator, a flow controller 6.

With a negative polarity of the regulating signal (when S t a + b t), the flow rate of the heat transfer fluid increases in proportion to the signal size; with a positive polarity, the flow is similarly reduced. With a change in the flow rate of the intermediate coolant, St and

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After the condition St (a + bf) is satisfied, in the absence of a mismatch between these signals, the regime is optimal for a given initial temperature range of the leaving combustion products, i.e. the maximum water heating and the minimum temperature of the combustion waste products after the contact heat exchanger 3, the empirical coefficients a and b for the range of initial temperatures of the combustion exhaust products 130-170 ° С are equal respectively (-28.25) and 1.04, and for the range 240 - 280 ° С - respectively (-22.2) and 0.9.

Claims (1)

Invention Formula The method of automatic control of the contact heat exchanger of combustion products with a closed circulation loop intermediate heat carrier containing a surface heat exchanger with the circulation circuit of the heated medium by varying the flow rate of the intermediate heat carrier depending on the parameter indirectly characterizing the degree of heat utilization, characterized in that, in order to increase the degree of heat utilization, the temperature of the heated medium is additionally measured and the temperature of the intermediate heat transfer medium at the exit of the heat exchanger, determine the temperature difference of the intermediate heat transfer medium ode of the heat exchanger and the heated medium at its inlet, and which ispolzz dissolved in an indirect parameter, the latter being further corrected for temperature of the heated medium at the outlet of the heat exchanger.,