CN110360593B - Coal mill trip control method under low-load three-coal-mill operation mode - Google Patents
Coal mill trip control method under low-load three-coal-mill operation mode Download PDFInfo
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- CN110360593B CN110360593B CN201910734721.8A CN201910734721A CN110360593B CN 110360593 B CN110360593 B CN 110360593B CN 201910734721 A CN201910734721 A CN 201910734721A CN 110360593 B CN110360593 B CN 110360593B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C25/00—Control arrangements specially adapted for crushing or disintegrating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
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- Combustion & Propulsion (AREA)
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- Control Of Steam Boilers And Waste-Gas Boilers (AREA)
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Abstract
The invention relates to a coal mill trip control method under the running mode of three low-load coal mills, which judges whether the coal mill trips or not under the running mode of three low-load coal mills, if so, judges according to the actual output of a unit and the maximum output of the remaining two coal mills, and adopts different control strategies for unit fuel control, water supply control and steam turbine control respectively to maintain the safe and stable running of the unit. Compared with the prior art, the invention solves the problem of trip control of the coal mill in a low-load three-mill operation mode.
Description
Technical Field
The invention relates to the technical field of automatic control and protection of thermal engineering, in particular to a coal mill trip control method under the operation mode of three low-load coal mills of a thermal power generating unit (hereinafter referred to as a low-load three-mill mode).
Background
The installation of new energy units is increasing day by day, and the low-load working condition operation of the thermal generator set becomes a normal state. The coal mill is used as an important auxiliary device of a boiler system, and the running mode of the coal mill directly influences the safe, stable and economic running of a unit. At present, in consideration of safe and stable operation of the unit during low load, four coal mills are still kept to operate under the low load working condition, any one coal mill trips, and the other three coal mills can quickly increase output power, maintain the heat load of a boiler, and reduce the influence of tripping of the coal mills on the safe and stable operation of the unit. However, the operation of 4 low-load coal mills has the problems that the coal quantity of a single coal mill is low, the operation reliability and stability of the coal mill are reduced, the overall power consumption of a pulverizing system is high, the low-load operation economy of a unit is influenced, and the like. By adopting a low-load three-mill operation mode, the actual coal quantity of operation of a single coal mill can be effectively improved, the long-time safe and stable operation of the coal pulverizing system is improved, the power consumption of the operation of the coal pulverizing system is reduced, and the operation economy of a unit is improved.
In the existing coal mill trip control technology, the method mainly aims at medium and high loads (the number of running coal mills is more than 3), belongs to the RB (auxiliary machine fault load reduction) category, and does not relate to the running working conditions of three low-load coal mills. In the low-load three-mill operation mode, any one coal mill trips in a fault, and because the output of the remaining two coal mills is limited by the output of the maximum coal amount of a single coal mill, the normal output of a unit cannot be maintained, the thermal load of a boiler drops suddenly, and the stable combustion of the boiler is seriously influenced; meanwhile, the water supply flow of the low-load unit is low, the rotating speed of the small unit is close to the lower limit, the water supply flow under the tripping working condition of the coal mill is difficult to control, the steam temperature fluctuation of the boiler is large, the wet operation is easy to enter, and the safe and stable operation of the unit is influenced. In the steam turbine set adopting the sequence valve steam inlet mode, the steam pressure of the steam turbine set is maintained under the tripping working condition of the coal mill, and the serious throttling working condition that the last two valves of the sequence valve are closed easily occurs, so that the safe and stable operation of a steam turbine is influenced. Therefore, aiming at the low-load three-mill operation mode, in order to meet the requirements of long-term operation of the three-mill operation mode and safe and stable operation of a unit under accident conditions, a coal mill trip control strategy and a system under the mode need to be designed and developed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a tripping control method of a coal mill in a low-load three-coal-mill operation mode.
The purpose of the invention can be realized by the following technical scheme:
a coal mill trip control method under the running mode of three low-load coal mills is characterized in that whether the coal mill trips is judged under the running mode of the three low-load coal mills, if yes, the judgment is carried out according to the actual output of a unit and the maximum output of the remaining two coal mills, different control strategies are adopted for unit fuel control, water supply control and steam turbine control respectively, and the safe and stable running of the unit is maintained.
Preferably, the judging whether the coal mill tripping occurs specifically includes:
and under the running mode of three coal mills with low load of the unit, the running condition of the coal pulverizing system is monitored in real time, and if any coal mill trips due to faults, tripping signals of the three coal mills with low load are triggered to run.
Preferably, the actual total coal quantity Q of the unit before the coal mill is trippedfuelThe total coal output Q of two coal mills in normal operationmaxComparing, and adopting different control strategies,
Preferably, if Qfuel＞QmaxThe following control strategy was employed:
1) the CCS control mode of the unit is removed, the main control and the fuel control of the boiler are switched to manual control, the coal feeding amount instructions of the remaining two coal mills which normally operate are directly set to be the single maximum coal amount, and the output of a coal pulverizing system of the unit is maintained to be Qmax；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) judgment of QfuelAnd QmaxIf the deviation exceeds a set value, connecting a recirculation valve of the feed water pump to a set position, accelerating the feed water flow rate reduction speed and maintaining the boiler steam temperature stable; meanwhile, triggering the water supply control to output a blocking pulse increasing signal, and setting the lower limit of the rotating speed instruction as the minimum safe rotating speed of the steam pump; if not, maintaining the normal control mode of the water supply flow;
4) if the steam turbine steam inlet regulating valve full-open operation mode is adopted, the full-open of the steam turbine regulating valve is maintained; if a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed.
Preferably, the set value in the step 3) is 5 +/-1 t/h.
Preferably, if Qfuel≤QmaxThe following control strategy was employed:
1) the CCS control mode of the unit is removed, the boiler main control is switched to manual control, the output of the coal mill before tripping is kept unchanged, the fuel main control is kept automatic, and the rest two coal mills which normally run are used as fuelThe output is automatically increased under the action of the master control, and the output of the unit pulverizing system is maintained to be Qfuel；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) if the steam turbine steam inlet regulating valve full-open operation mode is adopted, the full-open of the steam turbine regulating valve is maintained; if a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed.
Compared with the prior art, the invention solves the problem of trip control of the coal mill in the low-load three-mill operation mode, makes up for the technical blank, and meets the requirements of ensuring safe and stable operation of the unit under long-term operation and accident conditions in the three-mill operation mode.
Drawings
FIG. 1 is a flow chart of the operation of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
As shown in fig. 1, in the low-load three-mill operation mode of the present invention, when the coal mill trips, different control strategies are respectively adopted for the unit fuel control, the water supply control and the steam turbine control according to the actual output of the unit and the maximum output of the remaining two coal mills, so as to maintain the safe and stable operation of the unit:
and under the running mode of the unit low-load three-mill, the running condition of the coal pulverizing system is monitored in real time, and if any coal mill trips due to faults, a tripping signal of the low-load three-mill running coal mill is triggered. Actual total coal quantity Q of unit before tripping of coal millfuelThe total coal output Q of two coal mills in normal operationmaxMaking comparisons, e.g. Qfuel＞QmaxThen the following control strategy is adopted:
1) the CCS control mode of the unit is removed, the main control and the fuel control of the boiler are switched manually, the coal feeding amount commands of the remaining two coal mills which normally operate are directly set to be the maximum coal amount of a single coal mill, and the output of a coal pulverizing system of the unit is maintained to be Qmax；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) judgment of QfuelAnd QmaxIf the deviation exceeds a certain value (about 5 t/h), if the condition is met, the recirculation valve of the feed water pump is connected to a certain position, the feed water flow rate is accelerated, and the steam temperature of the boiler is kept stable. Meanwhile, triggering the water supply control to output a locking pulse increasing signal, and setting a lower limit of a rotating speed instruction according to a safe operation boundary of the small machine;
4) if the steam turbine steam inlet adjusting valve is in a full-open operation mode, the full opening of the steam turbine adjusting valve is maintained. If a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed.
And under the running mode of the unit low-load three-mill, the running condition of the coal pulverizing system is monitored in real time, and if any coal mill trips due to faults, a tripping signal of the low-load three-mill running coal mill is triggered. Actual total coal quantity Q of unit before tripping of coal millfuelThe total coal output Q of two coal mills in normal operationmaxMaking comparisons, e.g. Qfuel≤QmaxThen the following control strategy is adopted:
1) the CCS control mode of the unit is removed, the boiler main control is switched manually, the output of the coal mill before tripping is kept unchanged, the fuel main control is kept automatic, the output of the rest two coal mills in normal operation is automatically increased under the action of the fuel main control, and the output of the pulverizing system of the unit is kept to be Qfuel；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) if the steam turbine steam inlet adjusting valve is in a full-open operation mode, the full opening of the steam turbine adjusting valve is maintained. If a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The trip control of the coal mill is implemented under the low-load three-mill operation mode of a certain 660MW unit:
1) the unit operation load is 370MW, a B/C/D three-mill operation mode is adopted, and a DCS control system monitors the operation condition of the pulverizing system in real time. C, tripping the coal mill in case of fault, and triggering a tripping signal of the low-load three-mill running coal mill. C, before the coal mill trips, the actual total coal amount 126t/h of the unit is larger than the maximum output total coal amount 120t/h of the two remaining coal mills in normal operation (the maximum output of a single coal mill is 60t/h), and the following control strategy is adopted:
1) the CCS control mode of the unit is removed, the boiler main control and the fuel control are manually switched, the coal feeding amount commands of the remaining two normally-operated coal mills are directly set to be 60t/h of the maximum coal amount of a single coal mill, and the output of a pulverizing system of the unit is maintained to be 120 t/h;
2) starting a boiler CD layer oil gun in a combined mode to maintain stable combustion of the boiler;
3) and a recirculation valve of the water feeding pump is connected to a position of 30%, so that the feed water flow rate is accelerated, and the steam temperature of the boiler is kept stable. Meanwhile, water supply control is triggered to output a locking pulse increasing signal (pulse width is 20s), and the lower limit of a rotating speed instruction is set to be 3150r/min according to the safe operation boundary of the small machine;
4) the unit adopts the full open mode of steam turbine admission governing valve, then maintains the steam turbine governing valve and opens.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (3)
1. A coal mill trip control method under three coal mills of underload operation mode, characterized by that, this method is under three coal mills of underload operation modes, judge whether the coal mill trips, if yes, judge according to actual output and maximum output of two coal mills of the rest of the unit, adopt different control strategies to fuel control, water supply control and steam turbine control of the unit respectively, maintain the safe and stable operation of the unit;
actual total coal quantity Q of unit before tripping of coal millfuelThe total coal output Q of two coal mills in normal operationmaxComparing, and adopting different control strategies according to a comparison result;
if Qfuel＞QmaxThe following control strategy was employed:
1) the CCS control mode of the unit is removed, the main control and the fuel control of the boiler are switched to manual control, the coal feeding amount instructions of the remaining two coal mills which normally operate are directly set to be the single maximum coal amount, and the output of a coal pulverizing system of the unit is maintained to be Qmax；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) judgment of QfuelAnd QmaxIf the deviation exceeds a set value, connecting a recirculation valve of the feed water pump to a set position, accelerating the feed water flow rate reduction speed and maintaining the boiler steam temperature stable; meanwhile, triggering the water supply control to output a blocking pulse increasing signal, and setting the lower limit of the rotating speed instruction as the minimum safe rotating speed of the steam pump; if not, maintaining the normal control mode of the water supply flow;
4) if the steam turbine steam inlet regulating valve full-open operation mode is adopted, the full-open of the steam turbine regulating valve is maintained; if a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed;
if Qfuel≤QmaxThe following control strategy was employed:
1) the CCS control mode of the unit is removed, the boiler main control is switched to manual control, the output of the coal mill before tripping is kept unchanged, the fuel main control is kept automatic, the output of the rest two coal mills which normally run is automatically increased under the action of the fuel main control, and the unit is keptThe output of the pulverizing system is Qfuel；
2) Jointly starting oil guns adjacent to the rest running coal seam of the boiler to maintain stable combustion of the boiler;
3) if the steam turbine steam inlet regulating valve full-open operation mode is adopted, the full-open of the steam turbine regulating valve is maintained; if a sequence valve steam inlet mode is adopted, the unit is switched to a TF operation mode, and a steam turbine main control output lower limit is set, wherein the lower limit is a corresponding steam turbine main control output instruction when the last two valves of the sequence valve are closed.
2. The coal mill trip control method under the operation mode of three coal mills with low load according to claim 1, wherein the step of judging whether the coal mill trip occurs is specifically as follows:
and under the running mode of three coal mills with low load of the unit, the running condition of the coal pulverizing system is monitored in real time, and if any coal mill trips due to faults, tripping signals of the three coal mills with low load are triggered to run.
3. The method for controlling the trip of a coal pulverizer when operating with a low load of three coal pulverizers as claimed in claim 1, wherein the set value in step 3) is 5 ± 1 t/h.
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| CN111013803B (en) * | 2019-12-17 | 2021-04-30 | 浙江浙能技术研究院有限公司 | Coal mill power distribution-based thermal power generating unit coal amount distribution control method |
| CN112393228A (en) * | 2020-11-30 | 2021-02-23 | 华北电力科学研究院有限责任公司 | RB (reverse bearing) jumping and grinding control device and method for octagonal tangential coal-fired boiler |
| CN112628711A (en) * | 2021-01-11 | 2021-04-09 | 大唐黄岛发电有限责任公司 | Auxiliary engine fault stable combustion control method based on 600MW supercritical unit low load |
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| JPH10281401A (en) * | 1997-04-09 | 1998-10-23 | Nippon Steel Corp | Method and apparatus for preventing trip in low load operation of coal fired boiler |
| CN101482449B (en) * | 2008-01-08 | 2011-08-31 | 浙江省电力试验研究院 | Risk limitation method for fast runback test of thermoelectric generating set |
| CN103438419B (en) * | 2013-08-07 | 2015-10-28 | 华电电力科学研究院 | Pulverized coal preparation system method is started before the red switch of a kind of 1000MW one-level large bypath system unit |
| CN105289830B (en) * | 2015-11-30 | 2018-07-03 | 上海明华电力技术工程有限公司 | A kind of medium-speed pulverizer start-up and shut-down control method based on coal amount online compensation |
| CN105929710A (en) * | 2016-04-18 | 2016-09-07 | 中国神华能源股份有限公司 | RB overall working condition simulation test device and method |
| CN107185701B (en) * | 2017-06-01 | 2018-09-14 | 中国神华能源股份有限公司 | The method and apparatus resumed operation after tripping for coal pulverizer |
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