SU1636644A1 - Method for automatically controlling temperature of superheated steam in utility and process waste heat boiler - Google Patents

Description

The invention relates to a power system and can be used to control the temperature of superheated steam in an energy technological waste heat boiler (ETKU) using heat from the flue gases of the heater.

stove with a multistage superheater with superheaters installed between its steps.

The aim of the invention is to improve the accuracy of regulation.

The drawing shows the structures on the scheme of the system for controlling the temperature of superheated steam in the ETCU, which makes it possible to implement this method.

The energy-technology waste heat boiler 1, which uses heat from the flue gases of the furnace 2, has a multi-stage steam superheater 3, desuperheaters 4 and 5, drum 6.

The superheated steam temperature control system contains a sensor 7 for the fuel consumption entering the

furnace 2, sensor 8 for oxygen content in flue gases coming from furnace 2 to waste-heat boiler 1, sensor 9 for fuel consumption entering the sub-heating of waste-heat boiler 1. The first input of multiplying unit 10 is connected to sensor 7 for fuel entering into furnace 2 The second inlet is with a unit 11 of the specific volume of flue gases generated during the combustion of the fuel entering the furnace 2 under stoichiometric conditions. Setting device

12 coefficient of excess air, reduced by one, and unit

The 13th flow of air required for burning the fuel entering the underfloor of the waste-heat boiler 1, under stoichiometric conditions, is connected respectively to the second

and the third inputs of the unit 14 for calculating the amount of excess air supplied to the underfloor of the waste-heat boiler. The sensor 9 of the fuel input to the refilling of the recovery boiler is connected to the first input of the unit 14, and the unit 15 of the value of the air excess factor correction is connected to the fourth input of this unit. The sensor 9 is also connected to the first input of the multiplier 16, the unit 17 is connected to the second input of the unit 17 of the specific volume of flue gases generated during combustion of the fuel entering the sub-heating of the waste-heat boiler 1, under stoichiometric conditions. The second, third and fourth inputs of the summation unit 18 are connected to the outputs of blocks 10, 16, 14, respectively; its first input is connected to the output of block 19

five

0

five

0

five

the amount of air contained in the flue gases flowing from the furnace into the waste heat boiler per unit of time. The first inlet of block 19 is connected to the outlet of block 10, the second inlet is connected with sensor 8 of oxygen content in flue gases coming from the furnace to the waste heat boiler, and the third is connected to unit 20% of oxygen content in air.

The superheated steam temperature control system also includes a flue gas temperature sensor 21 on the superheater 3, a flue gas temperature sensor 22 at the superheater outlet 3, a superheated steam temperature sensor 23 at the entrance to the last superheater stage 3, a steam superheater temperature sensor 24, the sensor 25 superheated steam consumption. The sensor 21 of the flue gas temperature at the inlet to the superheater 3 is connected to the first (summing) input of the summation unit 26, the sensor 22 of the flue gas temperature at the outlet of the superheater 3 is connected to the second (subtractive) input of this block, the output of which is connected to the first input of the multiplication unit 27 The output of block 18 is connected to the second input. A superheated steam temperature sensor 23 at the entrance to the last stage of the superheater 3 is connected to the input of the differentiation unit 28. The first input of the dividing unit 29 is connected to the output of the unit 27, the second input is connected to the superheated steam flow sensor 25, and the output is connected to the input of the differentiation unit 30, the output of which is connected to the first input of the regulator 31. The second input of the regulator 31 is connected to the output of the unit 28 differentiation, a third input with a superheated steam temperature sensor 24 at the output of the superheater 3. The regulator 31 is connected to the actuator 32 of the regulator 33. The first input of the regulator 34 is connected to the output of the division unit 29, to the second input of the regulator 34 tchik 35 condensate flow to the desuperheater torus 5. The regulator 34 is connected to an actuator 36, regulator body 37. i

The method using the system is carried out as follows.

The signal of the fuel consumption sensor 7, - I entering the furnace 2 (В „), is supplied to the first input of the multiplication unit 10, and the signal of the setting device 1 1 is the specific volume of flue gases generated during the combustion of the fuel supplied to the furnace 2 , in stoichiometric conditions () - at its second input The output signal of unit 10 is the theoretical amount of flue gases generated during the combustion of fuel entering the furnace per unit time

toz

m / h

VA.r.O V VA.r.n

m3 / h

20

25

This signal arrives at the first inlet of the unit 19 for calculating the amount of air contained in the flue gases coming from the furnace into the ECCU unit at a time, and at the second entrance of the summing unit 18 for calculating the disturbing effect — the volume of flue gases at the inlet to the steam superheater. The second input of block 19 receives a signal from sensor 8 of oxygen in the flue gases of the furnace () to the third input a signal of the setter 20 percent oxygen content in air (21.0) Block 19 generates a signal of the amount of excess air in the furnace FROM &

V8.n 02n Vn-Bn / (21- ° zn arriving at the first input of block 18. The signal of the fuel consumption sensor 9 entering the EHTC sub-wall (VK) goes to the first input of the multiplication unit 16, to the second of its input the control signal 17 specific volume of flue gases generated during the combustion of fuel entering the ETKU underflooding under stoichiometric conditions (V. G1 /). Output signal

, -1 S of block 16, entering the third inlet d of block 18, is the theoretical amount of flue gases generated during fuel combustion in the subfloor of ETKU per unit time

35

40

thirty

Vr.K - VV, e

m3 / h

A.g.k.

The sensor signal 9 also enters the first input of the unit 14 for calculating the amount of excess air supplied to the subsoil ETKU, at its second input comes the signal of the setting unit 12 of the excess air ratio reduced by one (0 1), the third input is the setting signal of the setting device 13

0

five

0

five

the specific air flow required for burning the fuel entering the ETKU underfloating, under stoichiometric conditions (vЈK), to the fourth input is the signal of the setting unit 15 of the excess air coefficient correction value unit 14 generates a signal of the amount of excess air supplied to the fuel in flooding ETKU per unit of time

vj.f (Oi - rVk-1) VK-V ° 6K, m / h,

where the second value of the correction coefficient of excess air.

This signal arrives at the fourth input of summation unit 18. Block 18 generates a signal for the volume V of flue gases at the entrance to the superheater per unit time by the ratio

V.V.U.d.g.k (tf - / 5B% -). VJyBK +

ABOUT

+ В „

V VA.r.n.

V ™

Zn 2T - 02P

where V - disturbing effect, BK fuel consumption, incoming

d

35

40

30 UAA to

in the heating of the recovery boiler, m / h;

specific volume of flue gases generated during fuel combustion under stoichiometric conditions in a waste-heat boiler, m3 / m3;

C - coefficient of excess air in the underflooding of the recovery boiler;

/ 3 - the value of the correction coefficient. K

excess air; specific air flow rate required for combustion of fuel entering the subfloor of a waste heat boiler under stoichiometric conditions, m

3 / MY

d

B „fuel consumption coming

0

five

in the oven

V, v ,, is the specific volume of flue gases generated by the combustion of fuel under stoichiometric conditions in the furnace, the percentage of oxygen in the air; the percentage of oxygen in the flue gases of the furnace. The signal from the sensor 21 of the flue gas temperature at the entrance to the superheater (t., Hail) is fed to the summing input of the summation unit 26,

A.h.P.

21 ° 2P

its subtracting input receives a signal from the flue gas temperature sensor 22 at the output of the superheater (t2, rpafl). The output signal () of block 26 is fed to the first input of multiplication unit 27, its second input receives a signal of block 18, which is a disturbing effect (V ) by quantity of flue gases

The signal generated by block 27 of the amount of heat given off to the steam superheater by flue gases

V (t {- t), m / h-degrees, is fed to the first input of the dividing unit 29, to the second input - the signal of the flow sensor 25 of superheated steam. The output signal of the unit 29, which is a correction parameter

- V (- hail

D

pp

t

h

: „

arrives at the first input of block 30

Differentiation Regulator 31 receives a signal from block 30 of the rate of change of the correction parameter. The signal from the sensor 23 temperature overheated steam at the entrance to the last

the superheater stage enters the input of the unit 28 The output signal of the unit 28 is proportional to the rate of change of steam temperature at the entrance to the last stage of the superheater, as well as the sensor signal 24 of the steam temperature at the steam superheater and the bodies come to the second and third inputs of the regulator 31, respectively. The regulator acts through the actuator 32 on the regulator 33, which changes the flow of condensate to the latter along the steam cooler 4 The regulator 34 receives a signal according to the value of the corrective parameter t unit 29 and signal sensor 35 the superheated steam flow. The controller 34 is connected to an actuator 36, which is connected to the regulator 37, which changes the flow of condensate to the penultimate desuperheater 5.

invention formula

The method of automatic regulation of the temperature of superheated steam in an energy technological waste heat boiler using heat from smoke hectares

0

five

0

35

five

about

.-

50

call of the heating furnace and having a sub-flooded and multistage superheater with intercoolers installed between its stages, by changing the flow rate of cooling water for the latter along the steam superheater by changing the steam temperature at the outlet of the superheater, the rate of change of the steam temperature at the entrance to the last superheater stage and speed the change in the correction parameter equal to the ratio of the product of the volume of flue gases entering the superheater per unit of time, by the difference Perform flue gas inlet and outlet of the superheater to steam consumption, and by changing the flow rate of cooling water for the penultimate one along the steam superheater by changing the said correction parameter and the flow rate of cooling water, characterized in that, in order to improve the control accuracy, it is also measured the consumption of fuel entering the refining of the recovery boiler, the consumption of fuel entering the heating furnace, and the oxygen content in the flue gases flowing from the furnace into the recovery boiler, t is the value of the excess air ratio in the sub-heating of the waste-heat boiler, reduced by one, the correction value of the excess air ratio, the percentage of oxygen in the air, the specific volumes of flue gases formed during fuel combustion under stoichiometric conditions, respectively utilization boiler, the value of the specific air flow required for burning the fuel entering the sub-heating boiler in stoichiometric conditions, and determine the volume V of the smoke x gases entering the superheater per unit of time, by ratio

to vA.r + (V- (Bvk -i) -vB (,. BK +

+ VVn +

° SnBnVArn 21 - Og

where By, is the fuel consumption entering the sinking of the recovery boiler;

-rk

 R

V ° 6K

91636644

the specific volume of flue gases formed during fuel combustion under stoichiometric conditions in the boiler,

utilizer;

coefficient of excess air in the flooding of the recovery boiler;

the correction value of the coefficient of air excess JQ; specific air flow rate required for burning the fuel entering the sub-heating boiler at j

.G-P

ten

stoichiometric conditions; BV - fuel consumption entering the furnace;

specific volume of flue gases generated during fuel stopping under stoichiometric conditions in the furnace; 21 - the percentage of oxygen in the air;

Od is the percentage of oxygen in the flue gases flowing from the furnace into the recovery boiler.

 ,

Claims (1)

Claim A method for automatically controlling the temperature of superheated steam in an energy-technology recovery boiler using heat from the flue gases of a heating furnace and having underfloor and a multi-stage superheater with desuperheaters installed between its steps, by changing the flow rate of cooling water for the last desuperheater along the vapor temperature at the outlet of the desuperheater superheater, rate of change of steam temperature at the entrance to the last stage of the superheater and rate of change correctly parameter, equal to the ratio of the product of the volume of flue gases entering the superheater per unit time, by the temperature difference between the flue gases at the inlet and outlet of the superheater to the steam flow rate, and by changing the cooling water flow rate for the penultimate steam cooler next to the last along the steam, changing the mentioned correction parameter and the value cooling water flow rate, characterized in that, in order to improve the accuracy of regulation, additionally measure the flow rate of fuel entering the reuse of the waste heat boiler, the fuel consumption entering the heating furnace and the oxygen content in the flue gases entering the waste heat boiler from the furnace set the coefficient of excess air in the underflooding of the waste heat boiler, reduced by one, the amount of correction of the coefficient of excess air, the percentage of oxygen in the air , the values of specific volumes, flue gases generated during fuel combustion under stoichiometric conditions, respectively, in a heating furnace and boiler — utilization —. torus, the specific air flow rate required for the day of fuel combustion entering the boiler reheater under stoichiometric conditions, and the volume V of flue gases entering the superheater per unit time is determined by the ratio + where In to - fuel consumption entering the underflooding of the waste heat boiler; V ^{0 v} A.G. to - specific volume of smoke ha— a call arising from the combustion of fuel under stoichiometric conditions in a boiler utilizer; 5 & - coefficient of excess air in the underflooding of the waste heat boiler; R - the value of the correction coefficient 10 0 a percentage of excess air; - specific consumption of air necessary for burning fuel entering the sub- furnace boiler-utilizer in fifteen stoichiometric conditions; In _p - fuel consumption entering the furnace; specific volume of flue gases generated during fuel combustion under stoichiometric conditions in the furnace; 21 - percentage of oxygen in the air; O — percentage of oxygen in the flue gases coming from the furnace to the boiler.