CN117075655A - Four-valve combined control safe and efficient control method suitable for flue gas recycling - Google Patents
Four-valve combined control safe and efficient control method suitable for flue gas recycling Download PDFInfo
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- CN117075655A CN117075655A CN202311122131.2A CN202311122131A CN117075655A CN 117075655 A CN117075655 A CN 117075655A CN 202311122131 A CN202311122131 A CN 202311122131A CN 117075655 A CN117075655 A CN 117075655A
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 239000003546 flue gas Substances 0.000 title claims abstract description 60
- 238000004064 recycling Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000000779 smoke Substances 0.000 claims abstract description 69
- 230000001105 regulatory effect Effects 0.000 claims description 95
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
- 238000010586 diagram Methods 0.000 claims description 12
- 230000004907 flux Effects 0.000 claims description 4
- 239000007789 gas Substances 0.000 description 8
- 239000000428 dust Substances 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 4
- 239000002918 waste heat Substances 0.000 description 4
- 239000003245 coal Substances 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- PCTMTFRHKVHKIS-BMFZQQSSSA-N (1s,3r,4e,6e,8e,10e,12e,14e,16e,18s,19r,20r,21s,25r,27r,30r,31r,33s,35r,37s,38r)-3-[(2r,3s,4s,5s,6r)-4-amino-3,5-dihydroxy-6-methyloxan-2-yl]oxy-19,25,27,30,31,33,35,37-octahydroxy-18,20,21-trimethyl-23-oxo-22,39-dioxabicyclo[33.3.1]nonatriaconta-4,6,8,10 Chemical compound C1C=C2C[C@@H](OS(O)(=O)=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H]([C@H](C)CCCC(C)C)[C@@]1(C)CC2.O[C@H]1[C@@H](N)[C@H](O)[C@@H](C)O[C@H]1O[C@H]1/C=C/C=C/C=C/C=C/C=C/C=C/C=C/[C@H](C)[C@@H](O)[C@@H](C)[C@H](C)OC(=O)C[C@H](O)C[C@H](O)CC[C@@H](O)[C@H](O)C[C@H](O)C[C@](O)(C[C@H](O)[C@H]2C(O)=O)O[C@H]2C1 PCTMTFRHKVHKIS-BMFZQQSSSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
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Abstract
The four-valve combined control safe and efficient control method is suitable for flue gas recycling. In most automatic control systems, one controlled variable is controlled by one actuator, but for some special systems, there may be cases where multiple actuators together regulate one controlled variable. The invention comprises the following steps: judging the temperature of the outlet flue gas of the low-temperature economizer, executing the second step when the temperature of the outlet flue gas of the low-temperature economizer is more than 92.5 ℃, and executing the fourth step when the temperature of the outlet flue gas of the low-temperature economizer is less than 90 ℃; gradually closing the recirculation valve, and judging the temperature of the flue gas at the outlet of the low-temperature economizer after the recirculation valve is closed, if the temperature of the flue gas is still more than 92.5 ℃, opening the outlet valve of the low-temperature economizer to increase the flow rate; and firstly closing the inlet valve of the low-temperature economizer, and gradually closing the outlet valve of the low-temperature economizer if the smoke temperature is still low after the inlet valve is fully closed. The invention is used for four-valve combined control safe and efficient control.
Description
Technical Field
The invention belongs to the field of automatic control, and particularly relates to an automatic control method suitable for regulating single variables by multiple valves, which is used for accurately and efficiently controlling the outlet smoke temperature of a low-temperature economizer system.
Background
The low-temperature economizer is a device for improving the condensation water temperature by utilizing the flue gas waste heat at the outlet of the air preheater, reduces the flue gas temperature while improving the condensation water temperature, reduces the flue gas loss, and is easy to generate low-temperature corrosion in a low-temperature region of the heat exchanger when the flue gas temperature after heat exchange of the low-temperature economizer needs to be controlled within a reasonable range and the flue gas temperature after heat exchange is high, which indicates that the flue gas waste heat is not fully utilized and still has larger flue gas heat loss. In operation, the influence factors of the exhaust gas temperature at the outlet of the air preheater are more, and the exhaust gas temperature cannot be accurately controlled, so that the exhaust gas temperature at the outlet of the low-temperature economizer is controlled by adjusting the water side temperature of the low-temperature economizer.
In most automatic control systems, one controlled variable is controlled by one actuator, but for some special systems, there may be cases where multiple actuators together regulate one controlled variable. As shown in fig. 1, the booster pump provides circulating power for the water side in the operation of the low-temperature economizer, so as to ensure the pressure required by the flow of the water side. The four valves ABCD ensure the water side flow rate and the flue gas side temperature of the low-temperature economizer system.
The condensed water source at the inlet of the low-temperature economizer has two paths: one water source is condensed water before passing through the low-pressure heater, and is sent to the inlet of the low-temperature economizer after passing through the B-regulated valve, the other water source is condensed water after passing through the #7 and #8 low-pressure heaters, and is sent to the inlet of the low-temperature economizer after passing through the A-powered door, and the two water sources are as follows: the water source of condensed water after passing through the low-pressure heater is used as a common water source of the low-temperature economizer, and in normal operation, the A electric door is kept in a normally open state. The temperature of the water source before the condensed water passes through the low-pressure heater is lower, the water source is used as the inlet water temperature regulating water source of the low-temperature economizer, the inlet water temperature of the low-temperature economizer is controlled by regulating the B regulating valve, when the inlet water temperature needs to be reduced, the A regulating valve is opened to increase the cold water quantity, and when the inlet water temperature needs to be increased, the A regulating valve is closed to reduce the cold water quantity.
There are two ways to go from the outlet water source of the low-temperature economizer: one path of the water enters the deaerator after being mixed with condensed water from the low-price inlet of #6 after the valve is regulated by D, and the other path of the water enters the inlet of the low-temperature economizer again for heating after the valve is regulated by C.
In summary, the final control variable of the low-temperature economizer is the outlet flue gas temperature, when the outlet flue gas temperature of the low-temperature economizer is higher than the expected temperature, the inlet water temperature of the low-temperature economizer needs to be reduced to increase heat exchange, and when the outlet flue gas temperature of the low-temperature economizer is lower than the expected temperature, the inlet water temperature of the low-temperature economizer needs to be increased to reduce heat exchange.
In normal operation, the factors such as unit lifting load, start-stop coal mill, soot blowing and the like all influence the outlet exhaust gas temperature of the air preheater, so that the inlet flue gas temperature of the low-temperature economizer is changed greatly, and when the inlet flue gas temperature of the low-temperature economizer is changed, the inlet valve of the low-temperature economizer is required to be adjusted to adjust the water side temperature in order to ensure that the outlet flue gas temperature is in a reasonable range. Meanwhile, the outlet smoke temperature of the pre-heater is low in winter and deep peak regulation, the outlet smoke temperature requirement of the low-temperature economizer can not be met by adjusting the inlet valve of the low-temperature economizer, the inlet water temperature of the low-temperature economizer is required to be controlled by simultaneously matching with the outlet valve of the low-temperature economizer and the recirculation valve, on one hand, the outlet smoke temperature of the low-temperature economizer is difficult to accurately control during manual adjustment, on the other hand, the unit parameter is frequently changed, and the manual adjustment operation amount is large.
Disclosure of Invention
The invention aims to provide a four-valve combined control safe and efficient control method suitable for flue gas recycling, so as to solve the technical problems.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a four-valve combined control safe and efficient control method suitable for flue gas recycling comprises the following steps:
step one: judging the temperature of the outlet flue gas of the low-temperature economizer, executing the second step when the temperature of the outlet flue gas of the low-temperature economizer is more than 92.5 ℃, and executing the fourth step when the temperature of the outlet flue gas of the low-temperature economizer is less than 90 ℃;
step two: gradually closing the recirculation valve, and judging the temperature of the flue gas at the outlet of the low-temperature economizer after the recirculation valve is closed, if the temperature of the flue gas is still more than 92.5 ℃, opening the outlet valve of the low-temperature economizer to increase the flow rate;
step three: after the outlet valve of the low-temperature economizer is fully opened, if the smoke temperature is still more than 92.5 ℃, an inlet valve automatic adjusting mode of the low-temperature economizer is activated, and the inlet valve is gradually opened;
step four: and firstly closing the inlet valve of the low-temperature economizer, gradually closing the outlet valve of the low-temperature economizer if the smoke temperature is still low after the inlet valve is fully closed, and gradually opening the recycling valve of the low-temperature economizer if the smoke temperature of the outlet valve is still less than 90 ℃ after the outlet valve is closed to the minimum of 50%.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that when the inlet valve of the low-temperature economizer is fully opened, the logic judgment opening degree is more than 98%, if the flue gas temperature of the outlet of the low-temperature economizer is still more than 92.5 ℃, when the inlet valve of the low-temperature economizer is in an automatic state, an automatic valve adjusting mode of the inlet valve of the low-temperature economizer is activated, and the inlet valve is gradually opened to reduce the inlet water temperature of the low-temperature economizer;
if the outlet smoke temperature of the low-temperature economizer is less than 90 ℃, logic judges that the inlet regulating valve of the low-temperature economizer has an opening degree, the #7 low-pressure outlet electric valve is in a full-open state, and meanwhile, when the inlet regulating valve of the low-temperature economizer is in an automatic state, an automatic regulating mode of the inlet regulating valve of the low-temperature economizer is activated, and the inlet regulating valve is gradually closed.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that the valve adjusting and adjusting method of the outlet of the low-temperature economizer comprises the following steps: when the inlet valve of the low-temperature economizer is closed, the opening is smaller than 5%, if the temperature of the smoke at the outlet of the low-temperature economizer is smaller than 90 ℃, the outlet valve of the low-temperature economizer is required to be closed at the moment to reduce the flow rate so as to reduce the heat exchange with the smoke, and when the logic judges that the outlet valve of the low-temperature economizer is in an automatic state, an automatic regulating mode of the outlet valve of the low-temperature economizer is activated, and the outlet valve is gradually closed, so that the flow rate is reduced and the temperature of the smoke at the outlet is increased;
when the outlet smoke temperature of the low-temperature economizer is more than 92.5 ℃, if the recirculation valve of the low-temperature economizer is fully closed and the opening is less than 5%, the outlet valve of the low-temperature economizer needs to be opened, and when the logic judges that the outlet valve is in an automatic state, the outlet valve automatic regulation mode of the low-temperature economizer is activated, the outlet valve is gradually opened, the through flow is increased, and the outlet smoke temperature is reduced.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that the low-temperature economizer recycling valve adjusting method comprises the following steps: when the outlet smoke temperature of the low-temperature economizer is more than 92.5 ℃, the low-temperature economizer recirculation valve needs to be turned off preferentially, the logic judges that the low-temperature economizer recirculation valve has an opening, the opening is more than 5 percent, and when the and recirculation valve is in an automatic state, an automatic low-temperature economizer recirculation valve adjusting mode is activated, the recirculation valve is turned off gradually, and the smoke temperature is reduced;
when the smoke temperature of the outlet of the low-temperature economizer is less than 90 ℃, the inlet regulating valve of the low-temperature economizer is required to be closed preferentially, then the outlet regulating valve of the low-temperature economizer is closed, finally the recirculation regulating valve is opened, the logic judges that the outlet regulating valve of the low-temperature economizer is closed to the lower limit of 50%, and meanwhile, when the recirculation regulating valve is judged to be in an automatic state, the recirculation regulating valve automatic regulating mode of the low-temperature economizer is activated, and the recirculation regulating valve is gradually opened to improve the smoke temperature.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that the valve adjusting logic of the inlet valve of the low-temperature economizer is as follows: after the inlet regulating valve of the low-temperature economizer is activated, the smoke temperature regulating logic operation is started, when the logic judgment is carried out on the inlet regulating valve of the low-temperature economizer in an automatic state, the instruction of the inlet regulating valve of the low-temperature economizer is calculated through PID according to the deviation between the actual value and the set value of the outlet smoke temperature of the low-temperature economizer, and the regulating valve is controlled to automatically follow the action of the outlet smoke temperature.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that the valve adjusting logic of the outlet of the low-temperature economizer is as follows: after the outlet regulating valve of the low-temperature economizer is activated, the smoke temperature regulating logic operation is started, when the outlet regulating valve of the low-temperature economizer is judged to be in an automatic state, the instruction is calculated through PID according to the deviation between the actual smoke temperature value and the set value of the outlet of the low-temperature economizer, the logic diagram is shown in figure 6, and the outlet regulating valve of the low-temperature economizer is different from the inlet regulating valve in that the #7 low-pressure outlet electric door is kept in a normally open state in normal operation, so that the inlet regulating valve of the low-temperature economizer can be fully closed, and the outlet regulating valve of the low-temperature economizer ensures that the regulating lower limit of 50% needs to be set so as to ensure the flux of the low-temperature economizer.
The four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized in that the recirculation valve adjusting logic of the low-temperature economizer is as follows: after the recycling valve of the low-temperature economizer is activated, the smoke temperature adjusting logic operation is started, when the recycling valve of the low-temperature economizer is judged to be in an automatic state by logic, the instruction of the recycling valve of the low-temperature economizer is calculated through PID according to the deviation between the actual value and the set value of the smoke temperature of the outlet of the low-temperature economizer, and the valve is controlled to automatically follow the action of the smoke temperature of the outlet.
Advantageous effects
1. The invention avoids the occurrence of too low inlet water temperature and effectively prevents low-temperature corrosion caused by the too low water temperature by intelligently controlling the through-flow rate and the inlet water temperature of the low-temperature economizer.
2. The invention ensures that the temperature of the outlet smoke of the low-temperature economizer is kept stable at the set temperature on the premise of the maximum flux, reduces the fluctuation of the outlet smoke, ensures the high-efficiency operation of the electric dust removal after the smoke with stable temperature enters the electric dust removal, reduces the dust of the outlet smoke of the electric dust removal, and reduces the electricity consumption of the electric dust removal.
3. The automatic control valve can reduce the exhaust gas temperature to the greatest extent on the premise that the exhaust gas temperature of the outlet of the low-temperature economizer is not lower than the design exhaust gas temperature, ensures energy recovery on the premise that the exhaust gas temperature is controllable, improves the waste heat recovery utilization efficiency, effectively improves the unit efficiency, and reduces the power supply coal consumption.
4. The invention greatly reduces the operation amount of personnel and improves the automatic control level of the low-temperature economizer system.
Drawings
FIG. 1 is a diagram of auxiliary valve control logic for a low-temperature economizer inlet;
FIG. 2 is a low-temperature economizer outlet valve trim auxiliary logic diagram;
FIG. 3 is a low-level economizer recirculation valve adjustment auxiliary logic diagram;
FIG. 4 is a logic diagram of low-temperature economizer inlet valve trim adjustment;
FIG. 5 is a logic diagram of low-temperature economizer outlet valve trim adjustment;
FIG. 6 is a logic diagram of a low-level economizer recirculation valve trim;
fig. 7 is a logic diagram for regulating the electric regulating valve of the condensate water circulation.
Description of the embodiments
The invention seeks automatic control of the inlet valve, the outlet valve and the recirculation valve of the low-temperature economizer, so that each valve is automatically adjusted along with the set smoke temperature of the outlet of the low-temperature economizer in an automatic state, and meanwhile, the time of each valve participating in the action is considered, thereby ensuring that the adjustment achieves economy and simultaneously meeting the safety requirement. The invention can be divided into two parts, one part is the sequential logic of the inlet valve, the outlet valve and the recirculation valve of the low-temperature economizer which participate in regulation, and the other part is the action logic of the inlet valve, the outlet valve and the recirculation valve of the low-temperature economizer which follow the smoke temperature.
The low-temperature economizer comprises a sequential logic of inlet valve adjustment, outlet valve adjustment and recirculation valve adjustment;
the inlet valve adjusting, the outlet valve adjusting and the recirculation valve adjusting of the low-temperature economizer participate in the adjusting sequence as follows:
when the temperature of the flue gas at the low-temperature outlet is more than 92.5 ℃, if the recirculation valve of the low-temperature economizer has an opening degree, the recirculation valve is gradually closed, if the temperature of the flue gas is still more than 92.5 ℃, the outlet valve of the low-temperature economizer is opened to increase the through flow, and after the outlet valve of the low-temperature economizer is fully opened, if the temperature of the flue gas is still more than 92.5 ℃, the inlet valve of the low-temperature economizer is opened to reduce the inlet water temperature of the low-temperature economizer.
When the temperature of the low-temperature outlet flue gas is less than 90 ℃, firstly closing an inlet valve of the low-temperature economizer, reducing the cold water quantity at the inlet of the low-temperature economizer, gradually closing the outlet valve of the low-temperature economizer if the temperature of the flue gas is still low after the inlet valve is fully closed, reducing the flow rate, and gradually opening the recycling valve of the low-temperature economizer if the temperature of the flue gas at the outlet valve is still less than 90 ℃ after the outlet valve is closed to the minimum of 50%;
the specific logic design of the three regulating valves is as follows:
(1) Valve-regulating auxiliary logic for inlet of low-temperature economizer
As shown in FIG. 2, when the outlet valve of the low-temperature economizer is fully opened (the logic judgment opening is more than 98%), if the exhaust temperature of the outlet of the low-temperature economizer is still more than 92.5 ℃, which means that the exhaust temperature waste heat is not fully utilized, the inlet water temperature of the low-temperature economizer needs to be reduced to increase heat exchange, and when the inlet valve of the low-temperature economizer is in an automatic state, an inlet valve automatic regulation mode of the low-temperature economizer is activated, and the inlet valve is gradually opened to be large so as to reduce the inlet water temperature of the low-temperature economizer.
If the outlet smoke temperature of the low-temperature economizer is less than 90 ℃, the water temperature of the low-temperature economizer is supercooled, excessive heat exchange is performed between the low-temperature economizer and smoke, logic judgment is made that the inlet regulating valve of the low-temperature economizer has an opening degree (the opening degree is more than 5 percent), the #7 low-pressure outlet adding electric valve is in a full-open state, and meanwhile, when the inlet regulating valve of the upper low-temperature economizer is in an automatic state, an inlet regulating valve automatic regulating mode of the low-temperature economizer is activated, and the inlet regulating valve is gradually closed so as to improve the inlet water temperature of the low-temperature economizer.
(2) Low-temperature economizer outlet valve-regulating auxiliary logic
As shown in fig. 3, when the inlet valve of the low-temperature economizer is closed (opening is less than 5%), if the temperature of the flue gas at the outlet of the low-temperature economizer is less than 90 ℃, the outlet valve of the low-temperature economizer needs to be closed to reduce the flow rate so as to reduce the heat exchange with the flue gas, and when the logic judges that the outlet valve of the low-temperature economizer is in an automatic state, the outlet valve automatic regulation mode of the low-temperature economizer is activated, and the outlet valve is gradually closed, so that the flow rate is reduced and the temperature of the flue gas at the outlet is increased;
when the outlet flue gas temperature of the low-temperature economizer is more than 92.5 ℃, if the recirculation valve of the low-temperature economizer is fully closed (the opening is less than 5%), the outlet valve of the low-temperature economizer is required to be opened, and when the logic judges that the outlet valve is in an automatic state, the outlet valve automatic regulation mode of the low-temperature economizer is activated, the outlet valve is gradually opened, the flow rate is increased, and the outlet flue gas temperature is reduced.
(3) Low-temperature economizer recirculation valve-regulating auxiliary logic
As shown in fig. 4, when the outlet smoke temperature of the low-temperature economizer is more than 92.5 ℃, the low-temperature economizer recirculation valve needs to be turned off preferentially, and when the logic judges that the low-temperature economizer recirculation valve has an opening (the opening is more than 5 percent) and the and recirculation valve is in an automatic state, the low-temperature economizer recirculation valve automatic regulation mode is activated, the recirculation valve is turned off gradually, and the smoke temperature is reduced.
When the smoke temperature of the outlet of the low-temperature economizer is less than 90 ℃, the inlet regulating valve of the low-temperature economizer is required to be closed preferentially, then the outlet regulating valve of the low-temperature economizer is closed, finally the recirculation regulating valve is opened, the logic judges that the outlet regulating valve of the low-temperature economizer is closed to the lower limit of 50%, and meanwhile, when the recirculation regulating valve is judged to be in an automatic state, the recirculation regulating valve automatic regulating mode of the low-temperature economizer is activated, and the recirculation regulating valve is gradually opened to improve the smoke temperature.
In all logics, when the temperature of the flue gas at the outlet of the low-temperature economizer is between 90 and 92.5 ℃, the current opening degree of each valve is kept unchanged.
The inlet valve, the outlet valve and the recirculation valve of the low-temperature economizer follow the action logic of the smoke temperature;
(1) Valve regulating and adjusting logic for inlet of low-temperature economizer
After the inlet regulating valve of the low-temperature economizer is activated, starting to perform smoke temperature regulation logic operation, and logically judging that when the inlet regulating valve of the low-temperature economizer is in an automatic state, calculating an instruction according to the deviation between the actual value and the set value of the smoke temperature of the outlet of the low-temperature economizer through PID, and controlling the regulating valve to automatically follow the action of the smoke temperature of the outlet, wherein the logic diagram is shown in figure 5:
(2) Low-temperature economizer outlet valve regulating and adjusting logic
After the outlet regulating valve of the low-temperature economizer is activated, the smoke temperature regulating logic operation is started, when the outlet regulating valve of the low-temperature economizer is judged to be in an automatic state, the instruction is calculated through PID according to the deviation between the actual smoke temperature value and the set value of the outlet of the low-temperature economizer, the logic diagram is shown in figure 6, and the outlet regulating valve of the low-temperature economizer is different from the inlet regulating valve in that the #7 low-pressure outlet electric door is kept in a normally open state in normal operation, so that the inlet regulating valve of the low-temperature economizer can be fully closed, and the outlet regulating valve of the low-temperature economizer ensures that the regulating lower limit of 50% needs to be set so as to ensure the flux of the low-temperature economizer.
(3) Low-temperature economizer recirculation valve adjustment logic
After the low-temperature economizer recycling valve is activated, starting to perform smoke temperature adjustment logic operation, and logically judging that when the low-temperature economizer recycling valve is in an automatic state, calculating an instruction according to the deviation between the actual value and the set value of the outlet smoke temperature of the low-temperature economizer through PID, and controlling the valve to automatically follow the action of the outlet smoke temperature, wherein a logic diagram is shown in figure 7:
the invention is suitable for the automatic control method of the single variable of the multi-valve regulation, the automatic control output opening of each valve is influenced by the opening of another valve, the opening of each valve is mutually restricted, and the opening of each valve is logically controlled to lead the system to be in the optimal running state and be quickly and timely regulated.
Claims (7)
1. A four-valve combined control safe and efficient control method suitable for flue gas recycling is characterized by comprising the following steps of: the method comprises the following steps:
step one: judging the temperature of the outlet flue gas of the low-temperature economizer, executing the second step when the temperature of the outlet flue gas of the low-temperature economizer is more than 92.5 ℃, and executing the fourth step when the temperature of the outlet flue gas of the low-temperature economizer is less than 90 ℃;
step two: gradually closing the recirculation valve, and judging the temperature of the flue gas at the outlet of the low-temperature economizer after the recirculation valve is closed, if the temperature of the flue gas is still more than 92.5 ℃, opening the outlet valve of the low-temperature economizer to increase the flow rate;
step three: after the outlet valve of the low-temperature economizer is fully opened, if the smoke temperature is still more than 92.5 ℃, an inlet valve automatic adjusting mode of the low-temperature economizer is activated, and the inlet valve is gradually opened;
step four: and firstly closing the inlet valve of the low-temperature economizer, gradually closing the outlet valve of the low-temperature economizer if the smoke temperature is still low after the inlet valve is fully closed, and gradually opening the recycling valve of the low-temperature economizer if the smoke temperature of the outlet valve is still less than 90 ℃ after the outlet valve is closed to the minimum of 50%.
2. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 1, which is characterized by comprising the following steps: the low-temperature economizer inlet valve regulating and adjusting method is that when the low-temperature economizer outlet valve is fully opened, the logic judgment opening is more than 98 percent, if the low-temperature economizer outlet smoke temperature is still more than 92.5 ℃, when the low-temperature economizer inlet valve is in an automatic state, an automatic low-temperature economizer inlet valve regulating mode is activated, and the inlet valve is gradually opened to reduce the inlet water temperature of the low-temperature economizer;
if the outlet smoke temperature of the low-temperature economizer is less than 90 ℃, logic judges that the inlet regulating valve of the low-temperature economizer has an opening degree, the #7 low-pressure outlet electric valve is in a full-open state, and meanwhile, when the inlet regulating valve of the low-temperature economizer is in an automatic state, an automatic regulating mode of the inlet regulating valve of the low-temperature economizer is activated, and the inlet regulating valve is gradually closed.
3. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 1, which is characterized by comprising the following steps: the outlet valve adjusting method of the low-temperature economizer comprises the following steps: when the inlet valve of the low-temperature economizer is closed, the opening is smaller than 5%, if the temperature of the smoke at the outlet of the low-temperature economizer is smaller than 90 ℃, the outlet valve of the low-temperature economizer is required to be closed at the moment to reduce the flow rate so as to reduce the heat exchange with the smoke, and when the logic judges that the outlet valve of the low-temperature economizer is in an automatic state, an automatic regulating mode of the outlet valve of the low-temperature economizer is activated, and the outlet valve is gradually closed, so that the flow rate is reduced and the temperature of the smoke at the outlet is increased;
when the outlet smoke temperature of the low-temperature economizer is more than 92.5 ℃, if the recirculation valve of the low-temperature economizer is fully closed and the opening is less than 5%, the outlet valve of the low-temperature economizer needs to be opened, and when the logic judges that the outlet valve is in an automatic state, the outlet valve automatic regulation mode of the low-temperature economizer is activated, the outlet valve is gradually opened, the through flow is increased, and the outlet smoke temperature is reduced.
4. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 1, which is characterized by comprising the following steps: the method for adjusting the recirculation valve of the low-temperature economizer comprises the following steps: when the outlet smoke temperature of the low-temperature economizer is more than 92.5 ℃, the low-temperature economizer recirculation valve needs to be turned off preferentially, the logic judges that the low-temperature economizer recirculation valve has an opening, the opening is more than 5 percent, and when the and recirculation valve is in an automatic state, an automatic low-temperature economizer recirculation valve adjusting mode is activated, the recirculation valve is turned off gradually, and the smoke temperature is reduced;
when the smoke temperature of the outlet of the low-temperature economizer is less than 90 ℃, the inlet regulating valve of the low-temperature economizer is required to be closed preferentially, then the outlet regulating valve of the low-temperature economizer is closed, finally the recirculation regulating valve is opened, the logic judges that the outlet regulating valve of the low-temperature economizer is closed to the lower limit of 50%, and meanwhile, when the recirculation regulating valve is judged to be in an automatic state, the recirculation regulating valve automatic regulating mode of the low-temperature economizer is activated, and the recirculation regulating valve is gradually opened to improve the smoke temperature.
5. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 2, which is characterized by comprising the following steps: the inlet valve adjusting logic of the low-temperature economizer is as follows: after the inlet regulating valve of the low-temperature economizer is activated, the smoke temperature regulating logic operation is started, when the logic judgment is carried out on the inlet regulating valve of the low-temperature economizer in an automatic state, the instruction of the inlet regulating valve of the low-temperature economizer is calculated through PID according to the deviation between the actual value and the set value of the outlet smoke temperature of the low-temperature economizer, and the regulating valve is controlled to automatically follow the action of the outlet smoke temperature.
6. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 3, which is characterized by comprising the following steps of: the outlet valve adjusting logic of the low-temperature economizer is as follows: after the outlet regulating valve of the low-temperature economizer is activated, the smoke temperature regulating logic operation is started, when the outlet regulating valve of the low-temperature economizer is judged to be in an automatic state, the instruction is calculated through PID according to the deviation between the actual smoke temperature value and the set value of the outlet of the low-temperature economizer, the logic diagram is shown in figure 6, and the outlet regulating valve of the low-temperature economizer is different from the inlet regulating valve in that the #7 low-pressure outlet electric door is kept in a normally open state in normal operation, so that the inlet regulating valve of the low-temperature economizer can be fully closed, and the outlet regulating valve of the low-temperature economizer ensures that the regulating lower limit of 50% needs to be set so as to ensure the flux of the low-temperature economizer.
7. The four-valve combined control safe and efficient control method suitable for flue gas recycling according to claim 4, which is characterized by comprising the following steps: the recirculation valve adjusting logic of the low-temperature economizer is as follows: after the recycling valve of the low-temperature economizer is activated, the smoke temperature adjusting logic operation is started, when the recycling valve of the low-temperature economizer is judged to be in an automatic state by logic, the instruction of the recycling valve of the low-temperature economizer is calculated through PID according to the deviation between the actual value and the set value of the smoke temperature of the outlet of the low-temperature economizer, and the valve is controlled to automatically follow the action of the smoke temperature of the outlet.
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