CN113883496B - Water level control method for circulating pump of furnace - Google Patents
Water level control method for circulating pump of furnace Download PDFInfo
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- CN113883496B CN113883496B CN202111128557.XA CN202111128557A CN113883496B CN 113883496 B CN113883496 B CN 113883496B CN 202111128557 A CN202111128557 A CN 202111128557A CN 113883496 B CN113883496 B CN 113883496B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
- F22D5/26—Automatic feed-control systems
- F22D5/34—Applications of valves
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Abstract
The invention discloses a water level control method of a boiler circulating pump, which mainly relates to an automatic control technology of water level adjustment, dry and wet state conversion in the starting and stopping processes of an industrial direct-current boiler (with the boiler circulating pump) of a thermal power plant and the like.
Description
Technical Field
The invention mainly relates to an automatic control technology for water level adjustment, dry and wet state conversion in the starting and stopping processes of industrial direct-current boilers (with circulating pumps) of thermal power plants and the like, in particular to a circulating pump water level control method.
Background
In the current process of starting and stopping a once-through boiler (with a boiler circulating pump), water level adjustment and dry and wet state conversion are very critical operations. For a long time, limited by an automatic control technology, a manual operation mode is always adopted, and according to the operation ticket step, an operator comprehensively considers key points such as boiler water flow, water supply flow, main steam pressure, separator water level, separator water storage tank water level and the like, continuously adjusts adjustment amounts such as boiler water supply valve opening, rotation speed of a water supply pump and the like, and finally completes water level adjustment, dry state conversion and wet state conversion. During operation, there is a greater safety risk for the operation due to the difference in technical strength of personnel.
Disclosure of Invention
According to the problems, the invention discloses a boiler circulating pump water level control method, which is based on the industrial automatic control characteristics of a thermal power plant and the like, and realizes the automatic completion of water level adjustment, dry and wet state conversion and the like of a direct-current boiler (with a boiler circulating pump) from the aspects of intelligence, automation and safety, reduces the operation amount of personnel, reduces the safety risk, lays a foundation for realizing one-key start and stop of a unit in the future, and is used for solving the risk problem of manually completing the water level adjustment, dry and wet state conversion of the direct-current boiler (with the boiler circulating pump) in the prior art.
In some embodiments of the invention, a method of controlling the water level of a boiler circulating pump is disclosed, applied to a once-through boiler having a boiler water circulating pump.
The control method comprises the following steps:
judging the allowable condition of the once-through boiler water level control;
when the current running parameters of the once-through boiler reach the allowable conditions for controlling the water level of the once-through boiler, automatically adjusting the water level of a boiler water circulating pump;
judging the completion condition of the water level control of the once-through boiler in the automatic water level adjustment process of the boiler water circulating pump;
and according to the current water level parameter of the current furnace water circulating pump, when the current operation parameter of the once-through boiler is judged to reach the completion condition, the water level automatic adjustment of the furnace water circulating pump in the current stage is completed.
Based on the basic conception, the technical scheme is mainly divided into three parts, namely, automatic water level adjustment of a water storage tank of the separator, automatic operation from wet state to dry state, automatic operation from dry state to wet state, and automatic completion of water level adjustment, dry state and wet state conversion of a direct-current boiler (with a circulating pump of a furnace) and the like.
In practical technical applications:
1. automatic water level adjustment for water storage tank of separator
The allowable conditions of the once-through boiler water level control are as follows: the first operation state is that the furnace water circulating pump is started, the furnace water circulating pump outlet regulating valve reaches a first opening interval, and the main water supply electric door is closed.
The automatic water level adjusting process of the separator water storage tank comprises the following steps: judging and comparing the magnitude relation between the current separator water level change rate of the once-through boiler and the first change rate of the separator water level, the water level change rate of the separator water storage tank and the first change rate of the separator water storage tank;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively smaller than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, opening a bypass valve of the main water supply electric door;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively larger than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, continuously judging the magnitude relation between the change rate of the main air pressure of the direct-current boiler and the first change rate of the main air pressure;
if the main air pressure change rate of the once-through boiler is larger than the main air pressure first change rate, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the first water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the first water level of the water storage tank, opening a bypass valve of the main water supply electric door, and continuously executing comparison judgment of the current change rate of the water level of the separator and the change rate of the water level of the water storage tank of the direct-current boiler relative to the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator;
if the main air pressure change rate of the once-through boiler is smaller than the first change rate of the main air pressure, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively larger than the first water level of the separator and the first water level of the water storage tank, the bypass valve of the main water supply electric door is closed.
2. Automatic operation from wet to dry
The allowable conditions of the once-through boiler water level control are as follows: the unit operation of the once-through boiler reaches a first load interval, the unit time coal burning quantity reaches a first coal quantity interval and keeps stable, the once-through boiler operates in a wet state, a main water supply electric door is closed, and the rotating speed of a steam pump reaches a first rotating speed value;
the automatic operation process from wet state to dry state is as follows:
judging and comparing the relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the third water level of the water storage tank, continuously judging the magnitude relation between the opening of the outlet valve of the furnace circulating pump and the first opening of the outlet valve of the furnace circulating pump;
if the opening of the outlet valve of the circulating pump of the furnace is larger than the first opening of the outlet valve of the circulating pump of the furnace, closing the outlet valve of the circulating pump of the furnace, continuously judging and comparing the relationship between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank after the duration of the preset time period;
if the opening of the furnace circulating pump outlet regulating valve is smaller than the first opening of the furnace circulating pump outlet regulating valve, the furnace circulating pump outlet electric valve is fully closed, the furnace circulating pump is stopped and the water supply is automatically put into, so that the wet state to dry state automatic operation is completed;
judging and comparing the magnitude relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank, and simultaneously judging and comparing the magnitude relation between the difference between the water flow on the main steam and the boiler and the first difference between the water flow on the main steam and the water flow on the boiler, and the magnitude relation between the water flow on the main steam and the second difference between the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is smaller than the second difference between the main steam flow and the water flow on the boiler, closing the bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the water flow on the boiler, the first difference between the main steam flow and the water flow on the boiler, and the second difference between the main steam flow and the water flow on the boiler.
3. Automatic operation from dry to wet
The allowable conditions of the once-through boiler water level control are as follows: the unit operation of the once-through boiler reaches a first load interval and keeps stable, the boiler is operated in a dry state, the superheat degree of the once-through boiler is smaller than the first superheat degree, the main water supply electric door is closed, and the steam pump is withdrawn from parallel operation;
the automatic operation process from the dry state to the wet state is as follows:
releasing the automatic water supply, starting a furnace water circulating pump, and judging and comparing the relation between the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the water storage tank is greater than the second water level of the water storage tank, opening a large circulating pump outlet regulating valve, and judging and comparing the magnitude relation between the opening of the circulating pump outlet regulating valve and the first opening of the circulating pump outlet regulating valve;
if the opening degree of the outlet valve of the furnace circulating pump is smaller than the first opening degree of the outlet valve of the furnace circulating pump, continuously judging and comparing the relation between the water level of the water storage tank and the second water level of the water storage tank after the preset time length is continued;
if the opening of the boiler circulating pump outlet regulating valve is larger than the first opening of the boiler circulating pump outlet regulating valve, judging and comparing the magnitude relation between the main steam flow and the water flow difference on the boiler and the first difference value between the main steam flow and the water flow on the boiler and the second difference value between the main steam flow and the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the boiler water flow is smaller than the second difference between the main steam flow and the boiler water flow, closing a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is between the first difference between the main steam flow and the water flow on the boiler and the second difference between the main steam flow and the water flow on the boiler, the automatic operation from the dry state to the wet state is completed, and the automatic adjustment of the water level of the water storage tank of the separator is executed.
The three processes are written into the DCS in a modular mode, man-machine interaction is realized in the form of an operation window, the operation amount of personnel is reduced, the operation risk is reduced, and the automation rate is improved.
The invention has the beneficial effects that:
1) Effectively solves the safety risk brought by misoperation of personnel.
2) The operation efficiency is improved, and the working time is saved.
3) And the automatic input rate is improved.
Drawings
FIG. 1 is a flow chart of a process for automatically adjusting the water level of a water storage tank of a separator in a water level control method of a circulating pump of a furnace according to an embodiment of the invention;
FIG. 2 is a flow chart showing a process of automatically operating from a wet state to a dry state in a method for controlling the water level of a circulating pump of a furnace according to an embodiment of the present invention;
FIG. 3 is a flow chart showing a process of automatically operating the pump from a dry state to a wet state in a method for controlling the water level of the circulating pump in the furnace according to an embodiment of the present invention.
Detailed Description
The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
Based on the industrial automatic control characteristics of a thermal power plant and the like, the invention realizes the automatic completion of water level adjustment, dry state and wet state conversion and the like of a once-through boiler (with a boiler circulating pump) from the aspects of intelligence, automation and safety, and discloses a boiler circulating pump water level control method which is applied to the once-through boiler with a boiler water circulating pump.
The water level control method of the circulating pump comprises the following steps:
judging the allowable condition of the once-through boiler water level control;
when the current running parameters of the once-through boiler reach the allowable conditions for controlling the water level of the once-through boiler, automatically adjusting the water level of a boiler water circulating pump;
judging the completion condition of the water level control of the once-through boiler in the automatic water level adjustment process of the boiler water circulating pump;
and according to the current water level parameter of the current furnace water circulating pump, when the current operation parameter of the once-through boiler is judged to reach the completion condition, the water level automatic adjustment of the furnace water circulating pump in the current stage is completed.
Based on the above concept, it should be noted that, judging the allowable conditions of the once-through boiler water level control includes:
presetting a first running state of the once-through boiler, and comparing whether the current running state of the once-through boiler meets the first running state or not;
when the current running state of the once-through boiler meets the condition of the first running state, judging that the once-through boiler reaches the allowable condition of the once-through boiler water level control.
The completion conditions of the once-through boiler water level control include:
presetting a second running state of the once-through boiler, and comparing whether the current running state of the once-through boiler after the automatic adjustment process of the water level of the boiler water circulating pump meets the second running state;
when the current running state of the once-through boiler meets the condition of the second running state, judging that the once-through boiler reaches the completion condition of the once-through boiler water level control.
Based on the above description, the first operation state sets a plurality of different allowable conditions for controlling the water level of the once-through boiler according to preset different once-through boiler operation parameter combinations, and the different first operation states correspond to different automatic adjustment processes of the water level of the boiler water circulating pump.
And setting a plurality of different completion conditions for controlling the water level of the once-through boiler according to different preset once-through boiler operation parameter values in the second operation state, wherein the automatic adjustment process of the water level of the different boiler water circulating pumps corresponds to different second operation states.
In some embodiments of the present invention, the method for controlling the water level of the circulating pump of the furnace may specifically be:
when the current running state of the once-through boiler is judged to meet the first running state, executing an automatic adjustment process corresponding to the current first running state;
according to a plurality of different first operating states, corresponding to different operating parameter thresholds of the once-through boiler, comparing the current operating parameter value of the once-through boiler with the operating parameter threshold;
and adjusting the current operation parameter value according to the operation parameter threshold value to adjust the current operation state of the once-through boiler until the current operation state of the once-through boiler meets the condition of the second operation state corresponding to the current automatic adjustment process, and ending the automatic adjustment process of the water level of the boiler water circulating pump.
In practical production application, the automatic water level adjusting process of the boiler water circulating pump in the technical scheme of the invention mainly comprises three parts, namely automatic water level adjustment of a separator water storage tank, automatic wet-state to dry-state operation, automatic dry-state to wet-state operation, and automatic completion of water level adjustment, dry-state and wet-state conversion of a direct-current boiler (with the boiler circulating pump) and the like.
1. Automatic water level adjustment of separator water storage tank (as in figure 1)
The allowable conditions of the once-through boiler water level control are as follows: the first operation state is that the furnace water circulating pump is started, the furnace water circulating pump outlet regulating valve reaches a first opening interval, and the main water supply electric door is closed.
The operating parameter threshold includes:
the first rate of change of the separator water level, the first rate of change of the separator storage tank water level, the first rate of change of the main steam pressure, the first separator water level, the first storage tank water level and the second storage tank water level.
The automatic water level adjusting process of the separator water storage tank comprises the following steps: judging and comparing the magnitude relation between the current separator water level change rate of the once-through boiler and the first change rate of the separator water level, the water level change rate of the separator water storage tank and the first change rate of the separator water storage tank;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively smaller than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, opening a bypass valve of the main water supply electric door;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively larger than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, continuously judging the magnitude relation between the change rate of the main air pressure of the direct-current boiler and the first change rate of the main air pressure;
if the main air pressure change rate of the once-through boiler is larger than the main air pressure first change rate, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the first water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the first water level of the water storage tank, opening a bypass valve of the main water supply electric door, and continuously executing comparison judgment of the current change rate of the water level of the separator and the change rate of the water level of the water storage tank of the direct-current boiler relative to the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator;
if the main air pressure change rate of the once-through boiler is smaller than the first change rate of the main air pressure, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively larger than the first water level of the separator and the first water level of the water storage tank, the bypass valve of the main water supply electric door is closed.
2. From wet to dry state (see FIG. 2)
The allowable conditions of the once-through boiler water level control are as follows: the unit operation of the once-through boiler reaches a first load interval, the unit time coal burning quantity reaches a first coal quantity interval and keeps stable, the once-through boiler operates in a wet state, a main water supply electric door is closed, and the rotating speed of a steam pump reaches a first rotating speed value;
the operating parameter threshold includes:
the first water level of the separator, the third water level of the water storage tank, the first difference value of the main steam flow and the water flow on the boiler, the second difference value of the main steam flow and the water flow on the boiler, and the first opening of the boiler circulating pump outlet valve.
The automatic operation process from wet state to dry state is as follows:
judging and comparing the relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the third water level of the water storage tank, continuously judging the magnitude relation between the opening of the outlet valve of the furnace circulating pump and the first opening of the outlet valve of the furnace circulating pump;
if the opening of the outlet valve of the circulating pump of the furnace is larger than the first opening of the outlet valve of the circulating pump of the furnace, closing the outlet valve of the circulating pump of the furnace, continuously judging and comparing the relationship between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank after the duration of the preset time period;
if the opening of the furnace circulating pump outlet regulating valve is smaller than the first opening of the furnace circulating pump outlet regulating valve, the furnace circulating pump outlet electric valve is fully closed, the furnace circulating pump is stopped and the water supply is automatically put into, so that the wet state to dry state automatic operation is completed;
judging and comparing the magnitude relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank, and simultaneously judging and comparing the magnitude relation between the difference between the water flow on the main steam and the boiler and the first difference between the water flow on the main steam and the water flow on the boiler, and the magnitude relation between the water flow on the main steam and the second difference between the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is smaller than the second difference between the main steam flow and the water flow on the boiler, closing the bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the water flow on the boiler, the first difference between the main steam flow and the water flow on the boiler, and the second difference between the main steam flow and the water flow on the boiler.
It should be noted that after the end of the sequential control, an operator should monitor the variation of the superheat degree of the outlet of the separator and adjust the bias of the superheat degree in time.
After the boiler circulating pump is stopped, operators should monitor the change conditions of parameters such as the wall temperature of the heating surface of the boiler.
3. Automatic operation from dry to wet (see FIG. 3)
The allowable conditions of the once-through boiler water level control are as follows: the unit operation of the once-through boiler reaches a first load interval and keeps stable, the boiler is operated in a dry state, the superheat degree of the once-through boiler is smaller than the first superheat degree, the main water supply electric door is closed, and the steam pump is withdrawn from parallel operation.
The operating parameter threshold includes:
the second water level of the water storage tank, the first opening of the outlet valve of the boiler circulating pump, the first difference value of the main steam flow and the water flow on the boiler, and the second difference value of the main steam flow and the water flow on the boiler.
The automatic operation process from the dry state to the wet state is as follows:
releasing the automatic water supply, starting a furnace water circulating pump, and judging and comparing the relation between the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the water storage tank is greater than the second water level of the water storage tank, opening a large circulating pump outlet regulating valve, and judging and comparing the magnitude relation between the opening of the circulating pump outlet regulating valve and the first opening of the circulating pump outlet regulating valve;
if the opening degree of the outlet valve of the furnace circulating pump is smaller than the first opening degree of the outlet valve of the furnace circulating pump, continuously judging and comparing the relation between the water level of the water storage tank and the second water level of the water storage tank after the preset time length is continued;
if the opening of the boiler circulating pump outlet regulating valve is larger than the first opening of the boiler circulating pump outlet regulating valve, judging and comparing the magnitude relation between the main steam flow and the water flow difference on the boiler and the first difference value between the main steam flow and the water flow on the boiler and the second difference value between the main steam flow and the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the boiler water flow is smaller than the second difference between the main steam flow and the boiler water flow, closing a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is between the first difference between the main steam flow and the water flow on the boiler and the second difference between the main steam flow and the water flow on the boiler, the automatic operation from the dry state to the wet state is completed, and the automatic adjustment of the water level of the water storage tank of the separator is executed.
It should be noted that, in practical production applications, the parameter threshold values in the three adjustment flows are set:
the first opening interval of the outlet valve of the furnace circulating pump is 50% +/-5%;
the first load interval is 200-240 MW;
the first coal quantity interval is 120-130 t/h;
the first rotational speed value is 4200rpm;
the first superheat degree is 10 ℃;
the first change rate of the water level of the separator is 0%;
the first change rate of the water level of the water storage tank of the separator is 0%;
the first change rate of the main steam pressure is 0%;
the first water level of the separator is 3m;
the first water level of the water storage tank is 6m, and the second water level of the water storage tank is 5.5m; the third water level of the water storage tank is 6.5m;
the first opening of the outlet valve of the circulating pump of the furnace is 50%;
the first difference value between the main steam flow and the water flow on the boiler is 100t/h, and the second difference value between the main steam flow and the water flow on the boiler is 50t/h;
the preset time period is 5s.
The three processes are written into the DCS in a modular mode, man-machine interaction is realized in the form of an operation window, the operation amount of personnel is reduced, the operation risk is reduced, and the automation rate is improved.
In the process of starting and stopping a direct-current boiler (with a boiler circulating pump), water level adjustment, dry and wet state conversion are very critical operations, and the boiler circulating pump water level control method is based on the industrial automatic control characteristics of a thermal power plant and the like, realizes the automatic completion of the water level adjustment, the dry and wet state conversion of the direct-current boiler (with the boiler circulating pump) from the aspects of intelligence, automation and safety, reduces personnel operation amount and safety risk, and lays a foundation for realizing one-key starting and stopping of a unit in the future.
The invention has the beneficial effects that:
1) Effectively solves the safety risk brought by misoperation of personnel.
2) The operation efficiency is improved, and the working time is saved.
3) And the automatic input rate is improved.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present invention, and these modifications and substitutions should also be considered as being within the scope of the present invention.
Claims (5)
1. A water level control method of a boiler circulating pump is applied to a once-through boiler with a boiler water circulating pump;
the method is characterized by judging the allowable condition of the once-through boiler water level control;
when the current running parameters of the once-through boiler reach the allowable conditions for controlling the water level of the once-through boiler, automatically adjusting the water level of the boiler water circulating pump;
judging the completion condition of the water level control of the once-through boiler in the automatic water level adjustment process of the boiler water circulating pump;
according to the current water level parameter of the furnace water circulating pump, when the current operation parameter of the once-through boiler is judged to reach the completion condition, the water level of the furnace water circulating pump at the current stage is automatically adjusted;
judging the allowable conditions of the once-through boiler water level control comprises the following steps:
presetting a first running state of the once-through boiler, and comparing whether the current running state of the once-through boiler meets the first running state or not;
when the current running state of the once-through boiler meets the condition of the first running state, judging that the once-through boiler reaches the allowable condition of the once-through boiler water level control;
the completion conditions of the once-through boiler water level control include:
presetting a second running state of the once-through boiler, and comparing whether the current running state of the once-through boiler after the automatic adjustment process of the water level of the boiler water circulating pump meets the second running state;
when the current running state of the once-through boiler meets the condition of the second running state, judging that the once-through boiler reaches the completion condition of the once-through boiler water level control;
the first operation state sets a plurality of different allowable conditions for the once-through boiler water level control according to the preset different once-through boiler operation parameter combinations;
the different first running states correspond to different automatic adjustment processes of the water level of the furnace water circulating pump;
the second operation state sets a plurality of different completion conditions of the once-through boiler water level control according to different preset once-through boiler operation parameter values;
the automatic adjustment process of the water level of the furnace water circulating pump corresponds to different second running states;
when judging that the current running state of the once-through boiler meets the first running state, executing the automatic adjustment process corresponding to the current first running state;
according to a plurality of different first operating states, corresponding to different operating parameter thresholds of the once-through boiler, comparing the current operating parameter value of the once-through boiler with the operating parameter threshold;
adjusting the current operation parameter value according to the operation parameter threshold value to adjust the current operation state of the once-through boiler until the current operation state of the once-through boiler meets the condition of the second operation state corresponding to the current automatic adjustment process, and ending the automatic adjustment process of the water level of the boiler water circulating pump;
the automatic water level adjustment process of the boiler water circulating pump comprises the following steps:
the water level of the water storage tank of the separator is automatically adjusted, and the water storage tank is automatically operated from a wet state to a dry state and from a dry state to a wet state.
2. The control method of claim 1, wherein the first operating state is set to: the first running state is that the water circulating pump is started, the outlet regulating valve of the furnace water circulating pump reaches a first opening interval, and the main water supply electric door is closed;
when the current running state of the once-through boiler meets the first running state, executing automatic water level adjustment of a water storage tank of the separator;
the operating parameter threshold comprises:
the first change rate of the water level of the separator, the first change rate of the water level of the water storage tank of the separator, the first change rate of the main steam pressure, the first water level of the separator, the first water level of the water storage tank and the second water level of the water storage tank;
judging and comparing the magnitude relation between the current separator water level change rate of the once-through boiler and the first change rate of the separator water level, the water level change rate of the separator water storage tank and the first change rate of the separator water storage tank;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively smaller than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, opening a bypass valve of the main water supply electric door;
if the change rate of the water level of the separator and the change rate of the water level of the water storage tank of the separator are respectively larger than the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator, continuously judging the magnitude relation between the change rate of the main air pressure of the once-through boiler and the first change rate of the main air pressure;
if the main air pressure change rate of the once-through boiler is larger than the first main air pressure change rate, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the first water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the first water level of the water storage tank, opening a bypass valve of the main water supply electric door, and continuously executing comparison judgment of the current change rate of the water level of the separator and the change rate of the water level of the water storage tank of the direct-current boiler relative to the first change rate of the water level of the separator and the first change rate of the water level of the water storage tank of the separator;
if the main air pressure change rate of the once-through boiler is smaller than the first change rate of the main air pressure, continuing to judge the size relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively larger than the first water level of the separator and the second water level of the water storage tank, the bypass valve of the main water supply electric door is closed.
3. The control method of claim 1, wherein the first operating state is set to: the unit operation of the once-through boiler reaches a first load interval, the unit time coal burning amount reaches a first coal amount interval and keeps stable, the once-through boiler operates in a wet state, a main water supply electric door is closed, and the rotating speed of a steam pump reaches a first rotating speed value;
executing automatic operation from wet state to dry state when the current running state of the once-through boiler meets the first running state;
the operating parameter threshold comprises:
the first water level of the separator, the third water level of the water storage tank, the first difference value of the main steam flow and the water flow on the boiler, the second difference value of the main steam flow and the water flow on the boiler, and the first opening of the outlet valve of the boiler water circulating pump;
judging and comparing the relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank;
if the water level of the separator and the water level of the water storage tank are respectively smaller than the first water level of the separator and the third water level of the water storage tank, continuously judging the magnitude relation between the opening of the outlet regulating valve of the furnace water circulating pump and the first opening of the outlet regulating valve of the furnace water circulating pump;
if the opening of the outlet regulating valve of the furnace water circulating pump is larger than the first opening of the outlet regulating valve of the furnace water circulating pump, closing the outlet regulating valve of the furnace water circulating pump, continuously judging and comparing the relationship between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank after the preset time period;
if the opening degree of the outlet regulating valve of the furnace water circulating pump is smaller than the first opening degree of the outlet regulating valve of the furnace water circulating pump, the electric door of the outlet of the furnace water circulating pump is fully closed, the furnace water circulating pump is shut down and the water supply is put into automation, and the automatic operation from a wet state to a dry state is completed;
judging and comparing the magnitude relation between the water level of the separator and the first water level of the separator, the water level of the water storage tank and the third water level of the water storage tank, and simultaneously judging and comparing the magnitude relation between the difference between the water flow on the main steam and the boiler and the first difference between the water flow on the main steam and the water flow on the boiler, and the magnitude relation between the water flow on the main steam and the second difference between the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a main water supply bypass valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is smaller than the second difference between the main steam flow and the water flow on the boiler, closing the bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the water flow on the boiler, the first difference between the main steam flow and the water flow on the boiler, and the second difference between the main steam flow and the water flow on the boiler.
4. The control method of claim 1, wherein the first operating state is set to: the unit operation of the once-through boiler reaches a first load interval and keeps stable, the boiler is operated in a dry state, the superheat degree of the once-through boiler is smaller than the first superheat degree, the main water supply electric door is closed, and the steam pump is withdrawn from parallel operation;
executing automatic operation from a dry state to a wet state when the current running state of the once-through boiler meets the first running state;
the operating parameter threshold comprises:
the second water level of the water storage tank, the first opening of the outlet regulating valve of the boiler water circulating pump, the first difference value of the main steam flow and the water flow on the boiler, and the second difference value of the main steam flow and the water flow on the boiler;
releasing the automatic water supply, starting a furnace water circulating pump, and judging and comparing the relation between the water level of the water storage tank and the second water level of the water storage tank;
if the water level of the water storage tank is greater than the second water level of the water storage tank, opening a gate of an outlet of the large furnace water circulation pump, and judging and comparing the magnitude relation between the gate opening of the outlet of the furnace water circulation pump and the first opening of the outlet of the furnace water circulation pump;
if the opening degree of the outlet regulating valve of the furnace water circulating pump is smaller than the first opening degree of the outlet regulating valve of the furnace water circulating pump, continuously judging and comparing the size relationship between the water level of the water storage tank and the second water level of the water storage tank after the preset time length is continued;
if the opening degree of the outlet regulating valve of the boiler water circulating pump is larger than the first opening degree of the outlet regulating valve of the boiler water circulating pump, judging and comparing the magnitude relation between the main steam flow and the first difference value between the main steam flow and the water flow on the boiler and the second difference value between the main steam flow and the water flow on the boiler;
if the difference between the main steam flow and the boiler water flow is larger than the first difference between the main steam flow and the boiler water flow, opening a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the boiler water flow is smaller than the second difference between the main steam flow and the boiler water flow, closing a bypass valve of the main water supply electric valve, and continuously judging and comparing the magnitude relation between the main steam flow and the boiler water flow, the first difference between the main steam flow and the boiler water flow, and the second difference between the main steam flow and the boiler water flow;
if the difference between the main steam flow and the water flow on the boiler is between the first difference between the main steam flow and the water flow on the boiler and the second difference between the main steam flow and the water flow on the boiler, the automatic operation from the dry state to the wet state is completed, and the automatic adjustment of the water level of the water storage tank of the separator is executed.
5. The control method according to any one of claims 2 to 4, wherein in the process of automatically adjusting the water level of the boiler water circulation pump, when a judgment condition that the operation parameter threshold is not satisfied exists, the current operation state of the once-through boiler satisfies a condition of a second operation state, and it is judged that the current operation parameter of the once-through boiler reaches the completion condition.
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