SU1455143A1 - System for automatic regulation of fuel feed into steam generator - Google Patents

Abstract

The invention can be used on thermal power plants in steam generators with direct injection mills. The purpose of the invention is to increase the reliability of the system during abrupt discharges of the steam generator operating as part of the power unit. The setpoint device 1 and the power unit power sensor 2 are connected to the control device 3, which has logical comparison units, stack memory, subtraction, timings, and time relays. In device 3, the actual power of the power unit is compared with a predetermined and with power decreases to values less than 60% of the nominal value, which are longer than a predetermined time interval, the device 3 puts into operation a regulator 11, which is connected to the starting fuel consumption sensor 12 and mechanism 13. This eliminates the extinction of the steam generator furnace during abrupt load sheddings. When the power unit modes are close to the nominal, the controller 4, connected to setpoint 1, sensor 2i, through differentiators 5 and logic block 7, to sensors of 6.8 heat generation and power of mills, controls 9 electric motors of 10 pulverized coal mills through station. VA and, accordingly, the filing of the latter in the furnace. 1 hp f-ly, 2 ill., 3tabl. i W yi SP

Description

The invention relates to the automation of thermal power plants, and more specifically to systems for the automatic control and regulation of the supply of fuel to a steam generator with direct-injection dust mills, operating as part of a power unit.

The aim of the invention is to increase the operational reliability during abrupt discharges of the steam generator operating in the power unit.

FIG. 1 shows a block diagram of an automatic control system for supplying fuel to a steam generator; in fig. 2 is a block diagram of the control device.

The system contains (FIG. 1) a setting device 1 of the required (conditional) power of the power unit generator and a power generator power sensor 2 connected to the inputs of the control device 3 and the pulverized fuel supply controller 4, to the other two inputs of the latter through differentiators 5 connected to the sensor 6 heat in the furnace and through a normally closed contact logic unit 7 - sensor 8 total power of the electric motors of the mills; the output of the regulator 4 is connected with the station 9 controlling the electric motors 10 of the raw coal feeders according to the number of mills. The output of the device 3 is connected to the input of the pilot fuel supply controller 11, to another input of which the fuel consumption sensor 12 is connected, and the output of the controller 11 is connected to the actuator 13 of the pilot fuel supply regulator.

Control unit 3 (Fig. 2) contains a block 14, which is a logical unit of comparison, the state of which is determined by the table. one"

Here, H, g, and N are the nominal and nominal power of the generator.

Unit 14 with its first input labeled C1, which is simultaneously the input of the entire control device 3, is connected to setpoint 1, and the second input of this unit with label K1 is connected to the first output of stack unit 15, in which the constants required for operating the control device 3. The outputs of block 14 are labeled with A1 when the output value is zero, and B1 with the output value equal to one.

Block 16, which is an arithmetic subtraction unit, is connected to inputs 1 and sensor 2 (inputs C1 and D1, respectively), and its output, equal to the difference (C1-D1), is connected to the first input of block 17, similarly by the function performed block 14.

The condition of block 17 is determined by the table. 2 (Njpg, is the actual power of the power unit generator).

The inputs of block 18, which is the logical AND block (conjunction), are connected to the outputs B1 and B2 of blocks 14 and 17. The values of the outputs of block 18, depending on the combinations of its inputs, are given in Table. 3

The output of block 18 through time relay 19 is connected to controller 11. Relay 19 has a time setpoint that can be stored as a short circuit constant in block 15 or is set mechanically on the relay 19 itself, the output of which is the output of control unit 3.

The automatic control system for the supply of fuel to the steam generator functions as follows.

During operation of the steam generator in the area of operating operational loads, which for the steam generators operating on pulp coal, is

0.6D

k nom

 D ,, D.

(one)

five

0

five

0

five

where D is the nominal load

t / h

with a constant load D, const the initial steady state takes place. For power unit inequality (1) corresponds to the range of electrical loads

0.6Y „„ „ё.

At the same time, the steam generator operates only on fuel-sized fuel with included mills or, as a last resort (p-1) mills, if one of them is under repair or in reserve. The current value of the specified electrical load comes from the system automation, the dispatcher, or from the power unit power control to the setpoint 1. In the original stationary mode, some constant value of the specified load is maintained within the specified limits. In this case, the magnitudes of the output signals of the setpoint 1 and sensor 2 are equal, i.e. the actual power is equal to the set one; at the output of the regulator 4, the control signal

Neither is there, therefore, the electric motors 10, which are controlled from station 9, rotate at a constant number of revolutions, ensuring a constant consumption of coal to the mills. At the same time, the signal from sensor 6 is constant, since the heat release value of the furnace is constant and, therefore, to controller 4 along differentiator 5 (after sensor 6) - the input of controller 4 will not be a signal. For the initial stationary mode, the number of operating mills is unchanged, and therefore the signal from the sensor 8 is constant and there is no closed contact on the line 5 of the logic unit 7 to the controller 4. The equality of signals from setpoint 1 and power sensor 2 to control device 3 leads to the fact that at the output of block 16 (fig 2) there is no signal, since the difference between the input signals is equal. zero and, therefore, there is no signal from the control device 3 to the controller 11, which is therefore not turned on, and the actuator 13 ensures the closed position of the regulator of the ignition fuel.

Let us consider the functioning of the proposed system in the case of a steam generator operating in the specified load range, but in the presence of some disturbances encountered in actual operation practice. If one of the mills is shut off by a system of technological protection with simultaneous shutdown of the mill and its raw coal source (10-i) or emergency shutdown of one feeder (10-i) with the cessation of fuel supply to the mill, then logic block 7, the normally closed contact of block 7 remains closed. The change in the value of the given load of the power unit, Ы, within the specified range, is, by itself, external disturbance at the input

50

sishal from the sensor. 8 will decrease at 45 ° the automatic PT system of VriMnrnaawMCT ttoggim tg ttttyt and

disconnecting the mill, the differentiator 5 will generate a speed signal, which through the closed contact of the unit 7 will go to the input of the controller 4. The signal from the sensor 6 will also be reduced, since the shutdown of one mill under the action of protection causes a sharp reduction in the fuel supply to the steam generator furnace. In case of emergency shutdown of only the raw coal feeder (10-i), when the mill remained in operation, there would be not a sharp, but a gradual reduction in the fuel supply to the furnace, since in the control mill the fuel supply to the steam generator. The actual load at the first moment of time remains unchanged, which triggers the regulator 4 in the right direction: when a signal appears to increase the speed of rotation of the raw coal feeder motors, and when K ,, КТ - to reduce it.

55

Now consider the operation of the system in case of a sharp reset of the value of a given load N, d beyond the specified range. At the input of the control device 3 (Fig. 2),

0

five

0

In my blowing (hammer, medium, etc.) there is always some coal,

In both cases, the controller 4 will be affected by both speed signals and there will be an increase in the supply of fuel by the mills remaining in operation,

. When one of the mills is disconnected after it has been emasted, t, e, after an early shutdown of the raw coal feeder, for example, to repair it, the normally closed contact of the logic unit 7 is opened and a screeching signal occurs at the input of the speed signal 4 only from the differentiator 5 connected to a heat generator 6 in the furnace. As in the first case, the action of the control device 3 will not be and the controller 11 remains disabled.

If, when the steam generator operates in the specified load range 5, one of the mills turns on, for example, at the command of the functional-group control system, a inhibit signal will be generated in the logic block 7 and the normally closed contact of this block will open to prevent the appearance of a false high-speed signal along the line differentiator 5 - normally closed contact of the block 7 - regulator 4, I A false signal arises in connection. due to the fact that the speed signal by the total power of electric motors

mills acts in the opposite direction to the load.

The change in the magnitude of a given load of the power unit, Ы, д within the specified range, is an external disturbance at the input pre0

five

0

5 ° automatic re system

° automatic PT systems vriMnrnaawMCT ttoggaim tg ttttyt and

boiling fuel supply to the steam generator. The actual load at the first moment of time remains unchanged, which triggers the regulator 4 in the right direction: when a signal appears to increase the speed of rotation of the raw coal feeder motors, and when K ,, КТ - to reduce it.

55

Now consider the operation of the system in case of a sharp reset of the value of a given load N, d beyond the specified range. At the input of the control device 3 (Fig. 2),

514

difference of signals Nj and N. The first of these signals in block 14 is compared with the constant K1, which is numerically equal to 0, because

, 6N, o ",

then a signal is output from output B1 of this block. Arrival: at the input of ari (a metric block 16 of their input signals N, and .. leads to the appearance at the input of block 17 I of a signal C2 exceeding I I 0,1NwoM, which triggers block 17.

 Simultaneous operation of both I blocks 14 and 17 leads in this mode to the appearance at output I of block 18 of a single signal, which i through time relay 19, designed to prevent false triggering of device 3 when short-term signals in its circuit, is fed to the controller 11 (figure 1). This signal starts from this controller to the actuator 13 of the regulating body for supplying heating fuel in accordance with the required flow rate of this fuel, which is measured by the sensor 12 th.

The supply of starting fuel (for example, fuel oil) makes it possible to eliminate the unfavorable combustion mode during an abrupt load shedding of the steam generator and the power unit as a whole.

Formula inventions

Claims (2)

1. An automatic control system for supplying fuel to a steam generator equipped with direct injection mills, containing a regulator for feeding pulverized coal, is output connected to a control station about A36 The electric motor of the raw coal feeder, and the inputs through the differentiators are connected to the heat-transfer sensors in the furnace and the total power of the electric motors of the mills, characterized in that, in order to increase reliability during abrupt load shedding of the steam generator operating as part of the power unit, it additionally contains the sensor and the setpoint of the power of the generator of the power unit, connected to the additionally executed inputs of the regulator of the supply of the ps-coal fuel, and serially connected control device, at the input s is connected to the sensor and setpoint power generator unit, the controller starting fuel supply equipped with starting fuel flow sensor and the executive mechanism telnsh Regulator starting fuel, 2. The system according to claim 1, wherein the control device comprises a stack memory unit, a logical comparison unit and a serially connected arithmetic summing unit, a second logical comparison unit, a logic unit AND the time relayj controlled output of which is the output of the control device, the generator power unit, the power unit is connected to the first inputs of the first logical unit of comparison and the arithmetic summing unit, the generator power sensor is connected to the second input of the arithmetic unit a unit, the unit outputs a stack memory connected to the second inputs of the comparison logic blocks and control input time switch and the output of the first logic comparison unit connected to the second input of the logic block I. five 0 State of block 14  5D 0.6N, N, .6N „„ Н, д БО, 6Ы, о „ Table A1 B1 Block 17 state Inputs Comparison Condition Entry Tags Magnitude C2 (N,) (N, A-N,) O, INHOM A2 К2 0,1N (N ,, - N ,,) бО, 1РЁ «В2 Table 3 two-position inputs of block 18 About About 1 1 ABOUT 1 o Table 2 Outputs Output labels Outward about about about 1