CN112902135B - Water supply bypass capacity selection method based on water supply bypass frequency modulation - Google Patents
Water supply bypass capacity selection method based on water supply bypass frequency modulation Download PDFInfo
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- CN112902135B CN112902135B CN202110287616.1A CN202110287616A CN112902135B CN 112902135 B CN112902135 B CN 112902135B CN 202110287616 A CN202110287616 A CN 202110287616A CN 112902135 B CN112902135 B CN 112902135B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B33/00—Steam-generation plants, e.g. comprising steam boilers of different types in mutual association
- F22B33/18—Combinations of steam boilers with other apparatus
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B35/00—Control systems for steam boilers
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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
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Abstract
The invention discloses a water supply bypass capacity selection method based on water supply bypass frequency modulation, which comprises the following steps of: the method comprises the steps of obtaining the flow of a water supply bypass required by frequency modulation by taking the variable load requirement of a unit as a target; determining the maximum value of the flow of a water supply bypass for flue gas denitration by taking the standard reaching of the flue gas denitration of the unit boiler as a boundary; determining the water supply bypass capacity meeting the water supply frequency modulation and denitration effects of the thermal power generating unit according to the maximum value of the water supply bypass flow required by frequency modulation and the water supply bypass flow for flue gas denitration, and finishing the selection of the water supply bypass capacity.
Description
Technical Field
The invention belongs to the field of frequency modulation and peak shaving of thermal power generation technologies, and relates to a water supply bypass capacity selection method based on water supply bypass frequency modulation.
Background
The new energy provides a large amount of clean power for people, and simultaneously brings great challenges to the safe operation and power supply guarantee of a power grid. At present, the frequency modulation of most of steam turbine generator units in China is realized by throttling through a high-pressure regulating valve, and the throttling of steam is irreversible loss, so that the running economy of the turbine generator units is reduced, and the reduction is more remarkable for a steam turbine adopting a throttling regulation mode.
Research into various auxiliary power regulation techniques has been the focus of attention of those skilled in the relevant science. The bypass water supply realizes the corresponding change of the high pressure steam extraction amount by quickly changing the water supply amount flowing through the high pressure steam extraction tank, so that the steam amount of the high pressure cylinder and the medium pressure cylinder of the steam turbine for acting changes, the short-time output power of the unit changes, and the essence is to utilize the energy storage of the boiler economizer. The water supply bypass does not have the adjusting capability generally, so the water supply adjusting bypass needs to be additionally arranged in a matching way. In fact, the bypass water supply regulation load has the advantages of fast response, large regulation capacity and simple control strategy, is one of technical routes with minimum modification on a unit and minimum economic influence in a plurality of auxiliary frequency regulation means, and has a small amount of unit trial applications at present.
However, the feed water bypass capacity of the feed water frequency modulation does not have a proper selection mode at present, and the influence of the feed water frequency modulation on the boiler flue gas denitration is not considered. Therefore, a water supply bypass capacity selection method based on the frequency modulation requirement of the unit and comprehensively considering the influence on denitration needs to be provided.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a water supply bypass capacity selection method based on water supply bypass frequency modulation.
In order to achieve the aim, the water supply bypass capacity selection method based on the water supply bypass frequency modulation comprises the following steps of:
the method comprises the steps of obtaining the flow of a water supply bypass required by frequency modulation by taking the variable load requirement of a unit as a target;
determining the maximum value of the flow of a water supply bypass for flue gas denitration by taking the standard reaching of the flue gas denitration of the unit boiler as a boundary;
and determining the water supply bypass capacity meeting the water supply frequency modulation and denitration effects of the thermal power generating unit according to the maximum value of the water supply bypass flow required by frequency modulation and the water supply bypass flow for flue gas denitration, and finishing the selection of the water supply bypass capacity.
The bypass flow Δ Q of the feed water required for frequency modulation is:
wherein, Delta Q is the flow of the water supply bypass, Delta H is the variable load, r is the serial number of the high-pressure heater, n is the serial number of the first-stage high-pressure heater with the highest pressure, t r Is the feed water enthalpy at the outlet of the r-th stage heater, t 5 The enthalpy of feed water at the inlet of the 1 st stage high-pressure heater, eta r The extraction efficiency of the r-th stage heater.
Extraction efficiency eta of r-th stage heater r Comprises the following steps:
wherein H r Is the equivalent enthalpy drop of the extracted steam corresponding to the heater r, q r The heat release in the heater r for 1kg of extracted steam.
The flow of the unit feed water bypass meets the following requirements:
T y -ΔT y ≥T SCR (3)
wherein, T y SCR inlet smoke temperature, delta T, before commissioning of feedwater bypass y For SCR inlet smoke temperature reduction value, T, before and after commissioning of water supply bypass SCR Inlet smoke meeting SCR standard requirementA minimum value of temperature.
SCR inlet smoke temperature reduction value delta T before and after operation of water supply bypass y Comprises the following steps:
wherein, T 1 Is the feed water temperature at the outlet of the high pressure heater, T 3 The main water supply temperature after the water supply bypass is put into operation.
Main water supply temperature T after water supply bypass operation 3 The enthalpy value of the feed water bypass feed water is determined, and the enthalpy value of the feed water bypass feed water and the feed water flow rate passing through the bypass are balanced by heat shown by the formula (5):
h 1 *(Q-ΔQ)+h 2 *ΔQ＝h 3 *Q(5)
wherein Q is the main feed water flow, h 1 The enthalpy value of feed water at the outlet of the high-pressure heater h 2 The enthalpy value h of the water supply at the outlet of the water supply bypass after the operation of the water supply bypass 3 The enthalpy value of the main feed water after the feed water bypass is put into operation.
The water supply bypass flow delta Q required by frequency modulation according to the formula (5) is as follows:
the maximum value of the feedwater bypass flow is calculated using the inlet flue gas temperature required for SCR as a boundary according to equations (3) to (6).
The invention has the following beneficial effects:
the water supply bypass capacity selection method based on the water supply bypass frequency modulation is characterized in that when the method is specifically operated, the water supply bypass flow required by frequency modulation is obtained by taking the variable load requirement of a unit as a target, the maximum value of the water supply bypass flow for flue gas denitration is determined by taking the standard of flue gas denitration of a boiler of the unit as a boundary, and the water supply bypass capacity meeting the water supply frequency modulation and denitration effects of a thermal power unit is determined by the water supply bypass flow required by frequency modulation and the maximum value of the water supply bypass flow for flue gas denitration, so that the water supply bypass capacity selection is finished by considering the influence on denitration on the basis of meeting the frequency modulation requirement of the unit.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Wherein, 1 is the boiler, 2 is the deNOx systems, 3 is the feedwater bypass system, 4 is main water supply system, 5 is turbo generator set, 6 is the electric wire netting.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, the method for selecting the capacity of the water supply bypass based on the water supply bypass frequency modulation simultaneously considers the influence of the flow change of the water supply on the unit load and the unit denitration effect in the water supply frequency modulation process; calculating the flow of a water supply bypass by taking the variable load requirement of the unit as a target; the flue gas denitration standard of the unit boiler is used as a boundary, and the upper limit of the flow of the water supply bypass meeting the flue gas denitration is given.
The invention discloses a water supply bypass capacity selection method based on water supply bypass frequency modulation, which comprises the following steps of:
the method comprises the steps of obtaining the flow of a water supply bypass required by frequency modulation by taking the variable load requirement of a unit as a target;
determining the maximum value of the flow of a water supply bypass for flue gas denitration by taking the standard reaching of the flue gas denitration of the unit boiler as a boundary;
and determining the water supply bypass capacity meeting the water supply frequency modulation and denitration effects of the thermal power generating unit according to the maximum value of the water supply bypass flow required by frequency modulation and the water supply bypass flow for flue gas denitration, and finishing the selection of the water supply bypass capacity.
The bypass flow Δ Q of the feed water required for frequency modulation is:
wherein, Delta Q is the flow of the water supply bypass, Delta H is the variable load, r is the serial number of the high-pressure heater, n is the serial number of the first-stage high-pressure heater with the highest pressure, t r Is the feed water enthalpy at the outlet of the r-th stage heater, t 5 The enthalpy of feed water at the inlet of the 1 st stage high-pressure heater, eta r Is of the r-th orderThe extraction efficiency of the heater.
Steam extraction efficiency eta of r-th stage heater r Comprises the following steps:
wherein H r Is the equivalent enthalpy drop of the extracted steam corresponding to the heater r, q r The heat release in the heater r for 1kg of extracted steam.
The flow of the unit water supply bypass meets the following requirements:
T y -ΔT y ≥T SCR (3)
wherein, T y SCR inlet smoke temperature, delta T, before commissioning of feedwater bypass y For SCR inlet smoke temperature reduction value, T, before and after commissioning of water supply bypass SCR And the minimum value of the inlet smoke temperature required by SCR reaching the standard is obtained.
SCR inlet smoke temperature reduction value delta T before and after operation of water supply bypass y Comprises the following steps:
wherein, T 1 Is the feed water temperature, T, of the outlet of the high pressure heater 3 The main water supply temperature after the water supply bypass is put into operation.
Main water supply temperature T after water supply bypass operation 3 The enthalpy value of the feed water bypass feed water is determined, and the enthalpy value of the feed water bypass feed water and the feed water flow rate passing through the bypass are balanced by heat shown by the formula (5):
h 1 *(Q-ΔQ)+h 2 *ΔQ＝h 3 *Q (5)
wherein Q is the main feed water flow, h 1 The enthalpy value of feed water at the outlet of the high-pressure heater h 2 The enthalpy value of the water supply at the outlet of the water supply bypass after the operation of the water supply bypass, h 3 The enthalpy value of the main feed water after the feed water bypass is put into operation.
The bypass flow Δ Q of the water supply required for frequency modulation is obtained according to equation (5):
the maximum value of the feedwater bypass flow is calculated using the inlet flue gas temperature required for SCR as a boundary according to equations (3) to (6).
The water supply bypass capacity selected by the invention can meet the frequency modulation requirement of the unit, does not influence the denitration effect of the boiler flue gas, and ensures the safe and stable operation of the unit.
Claims (1)
1. A water supply bypass capacity selection method based on water supply bypass frequency modulation is characterized by comprising the following steps:
the method comprises the steps of obtaining the flow of a water supply bypass of a frequency modulation demand by taking the variable load demand of a unit as a target;
determining the maximum value of the flow of a water supply bypass for flue gas denitration by taking the standard reaching of the flue gas denitration of the unit boiler as a boundary;
determining the water supply bypass capacity meeting the water supply frequency modulation and denitration effects of the thermal power generating unit according to the maximum value of the water supply bypass flow required by frequency modulation and the water supply bypass flow for flue gas denitration, and finishing the selection of the water supply bypass capacity;
the bypass flow Δ Q of the feed water required for frequency modulation is:
where, Δ Q is the water supply bypass flow, Δ H is the variable load, r is the high pressure heater serial number, n is the serial number of the highest pressure one-stage high pressure heater, t r Is the feed water enthalpy at the outlet of the r-th stage heater, t 5 Is the feed water enthalpy value of the inlet of the 1 st stage high pressure heater r The steam extraction efficiency of the r-th stage heater;
extraction efficiency eta of r-th stage heater r Comprises the following steps:
wherein H r Is the equivalent enthalpy drop of the extracted steam corresponding to the heater r, q r The heat release of 1kg of extracted steam in the heater r;
the flow of the unit feed water bypass meets the following requirements:
T y -ΔT y ≥T SCR (3)
wherein, T y SCR inlet smoke temperature, Delta T, before commissioning of feedwater bypass y For SCR inlet smoke temperature reduction value, T, before and after commissioning of water supply bypass SCR The minimum value of inlet smoke temperature required by SCR reaching the standard;
SCR inlet smoke temperature reduction value delta T before and after commissioning of water supply bypass y Comprises the following steps:
wherein, T 1 Is the feed water temperature at the outlet of the high pressure heater, T 3 The main water supply temperature after the water supply bypass is put into operation;
main water supply temperature T after water supply bypass operation 3 The enthalpy of the feed water by-pass is determined, and the enthalpy of the feed water by-pass and the flow rate of the feed water by-pass have heat balance shown in the formula (5):
h 1 *(Q-ΔQ)+h 2 *ΔQ＝h 3 *Q (5)
wherein Q is the main feed water flow, h 1 The enthalpy value of feed water at the outlet of the high-pressure heater h 2 The enthalpy value of the water supply at the outlet of the water supply bypass after the operation of the water supply bypass, h 3 The enthalpy value of the main water supply after the water supply bypass is put into operation,
the water supply bypass flow delta Q required by frequency modulation according to the formula (5) is as follows:
the maximum value of the feedwater bypass flow is calculated using the inlet flue gas temperature required for SCR as a boundary according to equations (3) to (6).
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| AU2007201125B2 (en) * | 2006-03-17 | 2008-03-13 | Downer Energy Systems Pty Ltd | A waste heat boiler (WHB) system |
| CN104595884A (en) * | 2015-01-29 | 2015-05-06 | 上海上电电力工程有限公司 | Flue gas temperature rise system for forced circulation of drum boiler to maintain normal operation of SCR (Selective Catalytic Reduction) |
| CN108843417A (en) * | 2018-07-04 | 2018-11-20 | 西安热工研究院有限公司 | The co-generation unit of complete thermoelectricity decoupling based on supercritical carbon dioxide circulation |
| CN108591041B (en) * | 2018-07-06 | 2023-05-26 | 华能国际电力股份有限公司 | Minimum flow recirculation valve control system and method for feed pump |
| CN110056853A (en) * | 2019-05-13 | 2019-07-26 | 国家电投集团电站运营技术（北京）有限公司 | Boiler thermodynamic system and its control method |
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