RU1809913C - Thermal deaerator automatic control device - Google Patents

Abstract

Usage: heat power and can be used in the automation of technological processes in thermal deaerators of thermal and nuclear power plants. SUMMARY OF THE INVENTION: the device comprises a pressure regulator, the outputs of which are connected to actuators of regulatory bodies. The inputs of the pressure regulator are connected through the first and second elements to a dead zone with the outputs of the first and second comparison elements. The inputs of the first and second comparison elements are respectively connected to the outputs of the converter and the saturation temperature calculation unit, the inputs of which are connected to the sensors of parameters characterizing the deaeration process. 1 s.p. and piano, 3 ill.

Description

The invention relates to a power system, in particular to water treatment systems, and can be used in the automation of technological processes in thermal deaerators of thermal and nuclear power plants, as well as industrial heat power plants.

The purpose of the invention is to increase the efficiency of the thermal deaerator,

Significant differences of the claimed device are the introduction of a heating steam flow sensor, a heating steam temperature sensor, a deaerated water flow sensor, a first element with a dead zone, a second element with a dead zone, a saturation temperature calculation unit, a first comparison element, a deaerated water temperature sensor , a deaerated water temperature to pressure transducer, a second comparison element and new connections

ate

WITH

between additionally entered elements and other elements.

New connections (connection of the first input of the saturation temperature calculation unit with the output of the deaerated water flow sensor, the second input - with the output of the deaerated water temperature sensor, the third input - with the output of the heating steam flow sensor, the fourth input - with the output of the heating steam temperature sensor, fifth the input with the output of the deaerated water flow sensor, and the output with the second input of the second comparison element, the first input of which is connected to the output of the deaerated water temperature sensor and to the input of the temperature transducer ature of deaerated water into pressure, and the outlet - with the input of the second element with a dead zone, the output of which is connected to the second input of the steam pressure regulator, the first input of which is connected to the output

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oh che oh

ttl

CA

 CA

the first element with a dead zone, the input of which is connected to the output of the first comparison element, the first input of which is connected to the output of the steam pressure sensor in the deaerator, and the second - with the output of the temperature converter and deaerated water to pressure, can improve the efficiency of the deaerator,

In FIG. 1 is a block diagram of an apparatus for automatically controlling a thermal deaerator.

The device comprises a thermal deaerator 1, a steam pressure sensor 2 in the deaerator, a deaerated water flow sensor 3, a deaerated water temperature sensor 4, a heating steam flow sensor 5, a heating steam temperature sensor b, a deaerated water flow sensor 7, a deaerated water temperature sensor 8, a unit 9, saturation temperature calculation, first comparison element 10, second comparison element 11, deaerated water temperature to pressure transducer 12, first element 13 with dead band, second element 14 with dead band elnosti, the controller 15 steam pressure, the first actuator 1 is used, the second actuator 17, a first regulator 18, second regulator 19.

The saturation temperature calculating unit 9 can be built in both analog and digital versions. In FIG. Figure 2 shows a possible version of the technical implementation of the indicated block based on analog technology.

The saturation temperature calculating unit 9 comprises a first coefficient adjuster 20, a second coefficient adjuster 21, a first analog-to-digital converter 22, a first read-only memory 23, a first digital-to-analog converter 24, a first multiplication unit 25, a second multiplication unit 26, and a third unit 27 multiplication, adder 28, non-linear element 29 and division unit 30.

Unit 9 for calculating the saturation temperature Ts (t) operates in accordance with the following heat balance equation for the deaerator:

Qx (t) + Qn (t) Qg (t) + QBb, n (t), (1)

Qx (t) CP1 Tx (t) Gt (t), (2)

Qn (t) <l (t) -Gn (t), (3)

Qg (t) C P2 Ts (t) - Gg (t), (4)

Wt) i (t) GBb, n (t), (5)

0

5

0

5

0

where Qx (t) is the amount of heat introduced into the deaerator with a flow of non-degassed water;

Qn (t) is the amount of heat introduced into the deaerator with a stream of heating steam;

Qg (t) is the amount of heat removed from the deaerator with a stream of decontaminated water;

Qebin (t) - the amount of heat removed from the deaerator with a vapor stream;

Gx (t) is the flow rate of non-deaerated water;

Gn (t) is the consumption of heating steam;

GgW deaerated water consumption; . GBbin (t) is the evaporation rate;

Tx (t) is the temperature of non-deaerated water;

Tn (t) is the temperature of the heating steam;

Ts (t) is the saturation temperature in the deaerator;

СР1 - heat capacity of non-deaerated water;

СР2 - heat capacity of deaerated water;

i (t) is the enthalpy of heating steam.

In equation (1), the main parameters that determine the heat balance are taken into account, taking into account equations (2-5), it takes the form;

With P1 Tx (t) Gx (t) + Γ (t); Gn (t) C P2 Ts (t) -Gg (t) + i (t) GBbm (t). (6)

Given that the vapor flow rate of 3 $ GBbin (t) is negligible, i.e. Oyp (Ф (0.01 -: - 0.002) -Gx (t), equation (6) can be represented as:

40

With pG Tx (t) -Gx (t) J-i (t) -Gn (t).

C P2 Ts (t) Gg (t).

(7)

From equation (7) we determine the algorithm for calculating the saturation temperature:

TM-C-prTx (t); fi (t) + i (t) -Gn (t) ,,

IsWСр2 -Gg (t) --- W

Block 9 determines the temperature Ts (t) of water saturation in accordance with algorithm (8). .

Taking into account that the vapor enthalpy i (t) is difficult to calculate from the values of the flow rate and temperature of the heating steam, in block 9 it is determined in accordance with the values given in the table of M. Vukalovich. In this case, block 9 determines the enthalpy of heating steam as follows: output analog signal Tn (t)

the steam temperature sensor is fed to the input of the first analog-to-digital converter 22, which converts the signal Tn (t) into a binary digital code, which is fed to the input of the first read-only memory 23, where digital codes corresponding to the enthalpy values I (t ) heating steam, depending on the values of the temperature of the heating steam Tn (t) in the range (105-150) ° С in increments of 1 ° С. The permanent storage device 23, depending on the value of the input digital code at the output, produces a single digital code corresponding to the value of the enthalpy i (t) of the heating steam. The specified code is fed to the input of the digital-to-analog converter 24, which converts the digital code into an analog signal. At the same time, at the output of the converter 24 there is an analog signal Г (t) corresponding to the temperature of the heating steam,

In order to prevent the possibility of obtaining uncertainty during the division operation, when the divider of the division unit 30 has a zero value, the output of the third multiplication unit 27 includes an insensitive element 29, which allows it to keep the minimum set value of D at its output when a signal with zero value.

 The deaerated water temperature to pressure converter 12 comprises a second analog-to-digital converter 31, a second read-only memory 32, and a second digital-to-analog converter 33 (see FIGS. 2 and 3). In the second read-only memory 32 of the converter 12, digital codes are stored corresponding to the pressure values of the deaerated water depending on its temperature in the range of (70-130) ° C in increments of 1 ° C according to the table values of M.P. Vukalovich.

The output analog signal Tg (t) of the deaerated water sensor 8 is fed to the input of the converter 12. In this case, the second analog-to-digital converter 31 converts the analog signal Tg (t) into a binary digital code, which is fed to the input of the second read-only memory 32. depending on the value 1 of the input digital code, the output memory 32 generates a single digital code corresponding to the pressure value under which deaerated water is located. The specified code is fed to the input of the second digital-to-analog converter 33, which converts the digital code into an analog signal Pg (t). Thus, the converter 12

provides high accuracy of converting the current temperature value of deaerated water to the corresponding pressure value, which allows to increase the efficiency of the deaerator.

The device operates as follows.

Non-deaerated water after chemical treatment with a temperature Tx (t) and the required flow rate Gx (t) enters the thermal deaerator 1. Heating steam with a temperature Tn (t) and a flow rate Gn (t) is introduced into the thermal deaerator 1 to heat the undeaerated water to a saturation temperature at which the maximum removal of corrosive gases from the water takes place. The deaerated water with a flow rate of Gg (t) is heated to a temperature of Tg (t) is discharged from deaerator 1, and the non-condensed peer and corrosive gases released from the water with a total flow rate (t) are discharged from deaerator 1.,

In order to maximize the removal of corrosive gases from the water, it is necessary to maintain the temperature of the water in the deaerator on the saturation line. Taking into account that during the operation of the deaerator, various disturbances arise that deviate the temperature of the deaerated water from the saturation temperature, the calculated saturation temperature Ts (t) is calculated by the unit 9 on the basis of the heat balance equation 1 of the deaerator, followed by comparison of the indicated temperature with the actual temperature deaerated water Tg (t).

Taking into account that the process of approximating the actual value of water temperature Tg (t) in deaerator 1 to the value of saturation temperature Ts (t) is inertial and lengthy, in order to increase the efficiency and speed of controlling the thermal deaerator before each input of pressure regulator 15 steam. elements 13,14 are included with a dead band, the value of which for each of these elements is 0.5 ° C. As soon as the current values of the mismatch signals ei (t), Ј2 (t), arriving at the inputs of the controller 15 through the elements 13,14, fall into the deadband of these elements, there is no signal at their output and the controller 15 temporarily stops controlling the thermal deaerator 1 .

At the output of the deaerated water temperature sensor 8, there is a signal proportional to the actual value of the water temperature at the outlet of the deaerator.

The specified signal is input to converter 12 and converts the temperature value Tg (t) of deaerated water to the corresponding pressure value Pg (t) of deaerated water.

The output signal Pg (t) of the converter 12 is compared with the output of the steam pressure sensor 2 Pn (t) in the first comparison element 10. Moreover, if the values of these signals are different, then at the output of the comparison element 10 a mismatch signal Јi (t) arises, defined by the following expression:

Ј1 (t) Pn (t) - Pg (t).

(9)

Then, the signal EI (t) passes through the first element 13 with a dead zone and the first input of the steam pressure regulator 15, which outputs at its first output a control signal Vi (t), which is input to the first actuator 16. The actuator 16 is provided with a control signal Vi (t) acts on the first regulator 18, and the flow rate of the heating steam changes, which helps to bring the pressure under which the deaerated water is closer to the steam pressure in the deaerator and to decrease the value of the mismatch signal ani Ј1 (t). As soon as the value of the mismatch signal ei (t) falls into the dead zone of the first comparison element 13, there is no signal at the output of this element and the controller 15 stops controlling the steam supply, which indicates that the temperature of the deaerated water has reached the saturation temperature.

In order to increase the efficiency of the deaerator and to maximize the removal of corrosive gases from the water, a correction loop has been introduced into the device, the principle of which is that the output signal Tg (t) of the deaerated water temperature sensor is compared with the output signal of the saturation temperature calculation unit 9. If the calculated value of the temperature of saturation of water differs from the actual value Tg (t) of the temperature of the deaerated water, then at the output of the second comparison element 11 a mismatch signal Ј2 (t) defined by the relation:

Ј2 (t) Ts (T) -Tg (t),

(10)

and supplied to the second input of the steam pressure regulator 15 through the second element 14c

dead zone. The steam pressure regulator 15, by the signal Ј2 (t), generates a control signal V2 (t), which from its second output is fed to the input of the actuator 17. The actuator 17 acts on the second regulator 19 and the vapor flow rate changes, which contributes to approximation of the actual temperature value of the deaerated water to the calculated value of the saturation temperature. This also leads to the maximum removal of corrosive gases from the water and increase the efficiency of the deaerator. .

Thus, the proposed technical solution allows high precision to maintain the temperature of the deaerated water on the saturation line, regardless of the change in vapor pressure in the deaerator or

changes in other parameters determining the deaerator operation (Gx (t), Tx (t), Gn (t), Tn (t)). At the same time, corrosive gases are removed as much as possible from the treated water and the deaerator efficiency is significantly improved.

Claims (2)

SUMMARY OF THE INVENTION 1. A device for automatically controlling a thermal deaerator, comprising a temperature sensor for deaerated water and a first regulating body with an actuator mounted on a heating steam supply pipe, distinguishes it so that, in order to increase accuracy, it contains a deaerated water temperature sensor, a deaerator steam pressure sensor, a deaerated water flow sensor, a steam pressure regulator, a second regulating body with an actuator installed on the outlet pipe of the heating flow sensor. steam, a deaerated water flow sensor, a heating steam temperature sensor, a first element with a dead zone, a second element with a dead zone, a saturation temperature calculation unit, the first input of which is connected to the output of the deaerated water flow sensor, the second input with the output of the deaerated water temperature sensor, the third input is with the output of the heating steam flow sensor, the fourth input is with the output of the heating steam temperature sensor, and the fifth input is with the output of the deaerated water flow sensor, the first and second elements with avneni converter deaerated water temperature in the pressure input connected to the output of the sensor temperature deaerated water zgan- Nogo binding to a first input of a second comparing element, the second input of which is connected with the output of the saturation temperature calculation unit, and the output of the second comparison element is connected to the input of the second element with a dead zone, the output of which is connected to the first input of the steam pressure regulator, the outputs of which are connected to the first and second actuators, the first input of the first is connected with the output of the steam pressure sensor in the deaerator, and its second input is with the output of the temperature converter of the deaerated water to pressure, and the output is with the input of the first element with a dead zone, the output to torogo connected to the second input of the regulator pressure steam torus .. 2. The device pop. 1, it is noteworthy that the saturation temperature calculation unit comprises in series a first coefficient setter and a first multiplication unit, a second input which is connected to the output of the deaerated water temperature sensor, and the third input to the output of the deaerated water flow, analog-to-digital converter, read-only memory, digital-to-analog converter, and a second multiplication unit, the second input of which is connected to the output of the first multiplication unit, and the second entrance - from the output of the second multiplication unit, connected in series to the second coefficient adjuster and the third multiplication unit, the second input of which is connected to the output of the deaerated water flow sensor, and output - with the input of a nonlinear element, the output of which is connected to the first input of the division unit, the second input of which is connected to the output of the adder, and the output - with the second input of the second comparison element, 9 and 1.4  Vai. Ј 0W3