CN115507346A

CN115507346A - A kind of adoption is reheated outside the stove and realizes the mechanical furnace decoupling and lowers 15794loss the power storage system

Info

Publication number: CN115507346A
Application number: CN202210899872.0A
Authority: CN
Inventors: 林书成
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-04-27
Filing date: 2022-07-28
Publication date: 2022-12-23

Abstract

Machine-furnace decoupling and low realization by adopting reheating outside furnace

The energy-loss energy-storage thermoelectric system is characterized in that a main steam pipeline is connected with a high-pressure bypass pipeline; the reheating bypass outside the furnace is arranged at the outlet of the high-pressure cylinder and the inlet of the intermediate pressure cylinderA decoupling reheater is connected in series on the reheating bypass outside the furnace; the reheating circulation pipeline is arranged between a hot end outlet of the reheater and a cold end inlet of the reheater, and the reheating circulation pipeline is connected with a decoupling reheater in series; the steam in the external reheating bypass exchanges heat with the steam in the reheating circulating pipeline in the decoupling reheater; a path of high-temperature steam is led out from a hot end outlet of the reheater and sent to an energy storage reheater to serve as a heat source, and the heat of the energy storage reheater is used for reheating the inlet steam of the low-pressure cylinder; the system simplifies the type selection and regulation of the ejector and improves the working safety of the high-pressure cylinder; flexible and high-parameter external steam and heat supply is provided; and the up-down peak regulation capability of the unit is obviously optimized.

Description

A kind of adoption is reheated outside the stove and realizes the mechanical furnace decoupling and lowers 15794loss the power storage system

Technical Field

The invention belongs to the field of thermoelectric decoupling of thermal power plants, and particularly relates to a method for realizing machine-furnace decoupling and low-voltage decoupling by adopting external reheating

A thermoelectric system for the loss of energy.

Background

The existing mechanical furnace decoupling system can connect an ejector group with a high-pressure cylinder for steam exhaust and is used for ejecting the high-pressure cylinder for steam exhaust. There are two problems in that: 1. uncertain influences exist on a steam turbine when an injector group works in the operation of a power plant; 2. as the decoupling amplitude of the machine furnace is enlarged, the boosting ratio n of the ejector needs to be increased, the working condition of the ejector is deteriorated, and the decoupling of the machine furnace has a certain upper limit; 3. even if a part of decoupling area is abandoned and the n value of the ejector is controlled within a certain range, the change in the range still causes the instantaneous injection ratio u to fluctuate, the flow rate Ma of power steam caused by the fluctuation still causes the fluctuation of the flow rate Mb of the sucked steam, the airflow of each steam extraction point fluctuates, and a DCS control system needs to realize a complex control process.

Meanwhile, when the existing machine furnace decoupling system deals with the pure condensation working condition of the machine set, the redundant hot reheat steam after the machine furnace decoupling is completely subjected to temperature reduction and pressure reduction and enters a low-pressure cylinder,

the loss is too large, and the efficiency is too low; and with the increase of the installed capacity of new energy, the thermal power plant needs to have not only the capacity of down peak regulation but also the capacity of up peak regulation when the power grid is in short of power. But the existing machine furnace decoupling system cannot additionally provide peak-load regulation capacity for the machine set.

The existing energy storage technical route has the advantages of strong flexibility of battery energy storage, high energy efficiency, high manufacturing cost, limited service life and poor cost performance; the conventional molten salt energy storage adopts electric heat conversion, and a huge electric heating module is needed, so that the system cost is increased; on the other hand, the energy efficiency problem of thermoelectric conversion exists when the unit is in pure condensation working condition to release heat.

Disclosure of Invention

The invention aims to provide a method for realizing machine-furnace decoupling and low temperature by adopting external reheating

And a power loss system. The solution of avoiding interference with the steam turbine is achieved by rearranging the ejector and the high-exhaust system. After the energy storage module is added, the up/down peak regulation capacity under the pure condensation working condition is solved. Can realize decoupling of engine and furnace, large parameter heat supply (steam) and low temperature of thermal power plant

Energy is lost. The invention thoroughly solves the problems of safety and variable working conditions in the decoupling of the engine and the furnace, simultaneously adopts a heat exchange mode in the energy storage/discharge process, has extremely low initial investment of unit power, completes the energy discharge process in a mode of reheating middle exhaust steam, has no cold end loss, and ensures that the integral energy efficiency of the whole storage cycle of the system is extremely high.

The power loss and energy storage thermoelectric system comprises a main steam pipeline, a high-pressure bypass pipeline, a high-pressure turbine cylinder, a medium-pressure turbine cylinder, a boiler reheater and a decoupling reheater; the main steam pipeline is connected with the high-pressure bypass pipeline and the high-pressure cylinder of the steam turbine;

the method is characterized in that a high-pressure cylinder steam exhaust pipeline is connected to a cold end inlet of a boiler reheater; the hot end outlet of the reheater is connected with the intermediate pressure cylinder of the steam turbine through an intermediate pressure cylinder steam inlet pipeline;

the external reheating bypass is arranged between the outlet of the high-pressure cylinder and the inlet of the intermediate pressure cylinder, and a decoupling reheater is mounted on the external reheating bypass in series;

the reheating circulation pipeline is arranged between a hot end outlet of the reheater and a cold end inlet of the reheater, and the reheating circulation pipeline is connected with a decoupling reheater in series;

the steam in the furnace external reheating bypass and the steam in the reheating circulation pipeline exchange heat in the decoupling reheater;

a steam ejector system is arranged in the reheating circulation pipeline; the high-pressure bypass pipeline is connected with a power steam inlet of the steam ejector system; the reheating circulating pipeline is connected with a suction steam port of the steam ejector system; the steam exhaust port of the steam ejector system is connected with the cold end inlet of the reheater.

Compared with the prior art, the invention has the beneficial effects that:

the high-pressure cylinder exhaust bypass is arranged, exhaust steam of the high-pressure cylinder is led out, and the external decoupling reheater is additionally arranged, so that the complete decoupling state of the machine furnace can be smoothly transited after the high-pressure side decoupling reaches the limit.

The ejector group is positioned in the thermal recycling loop, so that the working condition of the ejector becomes simple; only the hot outlet pressure needs to be boosted to the inlet pressure, the boost ratio is very low and is a fixed value (< 1.2), and the ejector group selection and regulation are greatly simplified. The injector group is not associated with the high pressure cylinder, eliminating the indeterminate effect on the high pressure cylinder.

The system has no problem of pressure increase ratio after the ejector is put into operation, and because the high emission does not return to the boiler reheater, the pressure of the boiler reheater is not restricted by the value of the characteristic coefficient N and can be higher than the corresponding value of the boiler load rate. Through the hot section air-vent valve, can artificially control the target pressure value of reheater hot section, reheat steam actual pressure can be higher than the reheat pressure that boiler load corresponds for the steam supply quality (pressure) of unit promotes greatly. Similarly, the injector n value is fixed, the variable working condition trend is single, the space for mutually adjusting the extracted steam of each path is extremely large, and the adaptability of external steam supply is enhanced. The power plant can greatly widen the industrial steam supply market by matching with the improvement of steam supply pressure and the improvement of steam quantity.

According to the system, the energy storage bypass is arranged on the middle-low pressure cylinder communicating pipe, heat is stored during decoupling, and secondary reheating is provided for low-pressure cylinder steam admission when the power grid requires more power generation, so that the up-down peak regulation capability with excellent cost performance is obtained. And an electric heater unit can be additionally arranged and the energy storage scale can be expanded, so that the peak regulation capability of the thermal power plant can be greatly enhanced.

Drawings

Fig. 1 is a system pipeline connection diagram.

In the figure: the system comprises a main steam pipeline 1a, a high-pressure bypass pipeline 1B, a high-pressure cylinder steam exhaust pipeline 1C, a reheater cold section inlet 1d, a reheater hot end outlet 1e, a decoupling reheating inlet pipeline 2, a decoupling reheating outlet pipeline 3, a decoupling reheater 4, a hot section pressure regulating assembly 5, a medium-pressure cylinder steam inlet pipeline 6, a steam ejector steam exhaust pipeline 7, a reheating cycle inlet pipeline 8, a reheating cycle outlet pipeline 9, a steam ejector system 10, a high-bypass external steam supply pipeline 11, a high-exhaust external steam supply pipeline 12, a hot-bypass external steam supply pipeline 13, an energy storage bypass pipeline 14, an energy storage heat exchanger 15, a peak-down regulation steam supply pipeline 16, a reheating cycle steam return pipeline 17, a high-temperature molten salt tank 18a, a low-temperature molten salt tank 18B, a peak-up peak-regulation medium-pressure exhaust reheating pipeline 19, a peak-up steam inlet pipeline 20, an off-site or in-site power grid 21, a medium-low-pressure cylinder communicating pipe 22, a high-side unit interconnecting pipe 23, a power steam inlet A, a suction steam inlet B and a steam exhaust port C.

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 only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme of the invention is not limited by the capacity of the power plant unit.

The technical scheme of the invention is not limited by the newly built or operated power plant unit.

The technical scheme of the invention is not limited by the participation of the power plant unit in deep thermoelectric decoupling and the number of heat supply units.

The technical scheme of the invention is not limited by steam parameters of the plant unit.

The technical scheme of the invention is not limited by the cogeneration or pure condensation working condition of the power plant unit.

The technical scheme of the invention is not limited by a heating thermodynamic system of a power plant.

The technical scheme of the invention is not limited by energy storage working media (molten salt, heat conduction oil, solid heat storage, phase change heat storage and the like), energy storage reheater types and positions.

The loss energy storage thermoelectric system and method can realize complete decoupling of the unit, large-parameter heat (steam) supply and low power consumption on the premise of not transforming a main machine and not interfering a steam turbine

Energy is lost. And the energy distribution among electricity, heat (steam) and storage is flexible and efficient, the high flexibility requirement of a power grid, a heat supply network and a steam network on thermal power can be better met, the scale of heat supply/steam supply can be greatly enlarged, new energy consumption is increased, a power plant can be made into a comprehensive energy supply core (steam supply, heat supply, power supply and refrigeration and flexibility supply), so that the released capacity and electric quantity can meet the requirement of surfing the Internet by more new energy sources, the scale of energy storage construction is reduced, and great contribution is made to a double-carbon target.

The system can be called as a BERL system for short, and consists of three sub-modules:

1. arranging (or utilizing) an original Bypass pipeline (Bypass) on a high-pressure cylinder exhaust pipeline, and installing a steam-steam heat exchanger to form an External Reheater module (External Reheater);

2. a steam ejector group is adopted to construct a heat recycling module (regenerator Recycle), so that the flow balance of a boiler Reheater is realized;

3. realize low

The energy loss and Heat Storage (Low energy-lost Heat Storage), namely the energy Storage reheating module.

The external reheater module and the thermal recirculation module are configured simultaneously to achieve the decoupling function.

If the energy storage module adopts an electric heater mode, the energy storage/heat release process can be independently realized. The energy storage module is matched with the external reheater module and the thermal recycling module, so that the investment of the electric heater can be greatly saved, or the energy storage power of the system can be improved.

The three modules are matched, so that large-parameter heat supply, high-pressure steam supply and flexibility peak regulation can be simultaneously met, efficient thermal power peak regulation can be realized under a pure condensation working condition, and the method is a brand-new subversive technical scheme in the thermal power flexibility field.

As shown in figure 1, the boiler body and the steam turbine body are not modified, all auxiliary machines of the boiler do not need to be modified, and the tail flue does not need to be modified under low load. All rotating machines on the side of the steam turbine do not need to be transformed, a regenerative system needs to be properly changed to adapt to the problem of large water supply quantity and insufficient regenerative steam extraction quantity, the load rate of the steam turbine can be set according to power grid dispatching, the load of a boiler can be determined according to the sum of electric load and thermal load, and in the process, the unit can be smoothly transformed from a conventional extraction condensing state to a complete decoupling state of the turbine.

The system comprises a main steam pipeline 1a, a high-pressure bypass pipeline 1b, a high-pressure cylinder of a steam turbine and a boiler reheater;

the main steam pipeline 1a of the power plant is connected with the high-pressure bypass pipeline 1b, and the main steam pipeline of the power plant is connected with the high-pressure cylinder of the steam turbine. A part of the high-temperature and high-pressure main steam from the main steam pipeline enters the high-pressure cylinder of the steam turbine, and the other part of the high-temperature and high-pressure main steam enters the high-pressure bypass pipeline 1b.

And a steam exhaust pipeline 1c of a high-pressure cylinder of the steam turbine is connected to an inlet 1d of a cold section of the reheater. The high pressure cylinder exhaust pipeline is provided with a valve, and the valve is gradually closed until the valve is completely closed when the furnace is decoupled.

The high-pressure bypass pipeline 1b is also connected with a high-pressure bypass external steam supply pipeline 11 to supply industrial steam to the outside.

The high-pressure bypass pipeline 1b is also connected with a high-side interconnection pipe 23 of an adjacent unit, and two adjacent unit systems are interconnected through the high-side interconnection pipe 23 of the adjacent unit. High side steam of adjacent units are interconnected and communicated so as to solve the problem of insufficient power steam when the units are switched from a normal working condition to a decoupling working condition. In the decoupling starting initial stage of the single unit machine furnace, the working condition point crossing is realized by using the power steam from the adjacent unit, and after the single unit machine furnace is decoupled and operated, the power steam of the local unit is abundant, so that the decoupling starting of the adjacent unit can be reversely supported. And the interconnection and intercommunication of high side steam of adjacent units can also be used for solving the problem of insufficient pressure holding capacity of the high-pressure cylinder.

The high-pressure cylinder steam exhaust pipeline 1c provides industrial steam to the external steam supply pipeline 12.

The system also comprises a steam turbine intermediate pressure cylinder and an intermediate pressure cylinder steam inlet pipeline.

The hot end outlet 1e of the reheater is connected with the steam turbine intermediate pressure cylinder through an intermediate pressure cylinder steam inlet pipeline 6 and used for driving the steam turbine intermediate pressure cylinder to do work.

The steam inlet pipeline 6 of the intermediate pressure cylinder is sequentially provided with a hot section pressure regulating assembly 5, an intermediate pressure cylinder flow control valve and an intermediate pressure regulating valve.

Steam at the outlet of the hot section of the reheater passes through the hot section pressure regulating assembly 5, the flow control valve of the intermediate pressure cylinder and the intermediate regulating valve, and enters the intermediate pressure cylinder after pressure (flow) adaptation.

The hot section pressure regulating component 5 tracks the requirement of heat and then the external steam supply pressure to follow, and can realize the heat and then pressure higher than the boiler load rate through pressure-holding regulation, so that the external steam supply potential of the unit is larger.

The hot section pressure regulating assembly 5 adopts a pressure retaining valve, has a pressure retaining and regulating function, and establishes a required pressure difference between an inlet and an outlet at the front end and the rear end of the hot section pressure regulating assembly under a certain flow parameter to meet a target pressure required by the hot end of the reheater.

The hot section pressure regulating assembly can adopt a multi-pressure-retaining valve parallel arrangement mode, 2 or 3 valves are used for obtaining accurate pressure difference regulation, and the calibers of the valves can be the same or different. For small-caliber pipelines, the hot section pressure regulating assembly can be realized by adopting a single valve.

The flow control valve of the intermediate pressure cylinder can control the steam admission Mm of the intermediate pressure cylinder, so that the Mm is matched with the steam admission Mh of the high pressure cylinder, and the axial thrust balance of the steam turbine is ensured. As the Mm and the Mh of the steam turbine have certain deviation-tolerance capability, the unit can be ensured to be within the safety margin range.

Further included in the system is an external reheat bypass and a decoupled reheater 4.

The reheating bypass outside the furnace is arranged between the outlet of the high-pressure cylinder and the inlet of the intermediate-pressure cylinder. The starting point of the reheating bypass 2 outside the furnace is on the exhaust pipeline of the high-pressure cylinder, and the end point is on the steam inlet pipeline of the intermediate-pressure cylinder.

A bypass connected to the high-pressure cylinder exhaust pipeline is connected to the intermediate-pressure cylinder steam inlet pipeline, and the junction end point of the furnace reheating bypass and the intermediate-pressure cylinder steam inlet pipeline is located at the downstream of the hot section pressure regulating assembly 5 and the intermediate-pressure cylinder flow control valve.

A valve is arranged on the reheating bypass outside the furnace. The external reheating bypass is provided with a decoupling reheater 4, and comprises an inlet pipeline 2 positioned on the upstream side of the decoupling reheater 4 and an outlet pipeline 3 positioned on the downstream side. The decoupling reheater 4 adopts a hairpin heat exchanger, partial or all high-pressure cylinder exhaust steam from a reheating bypass outside the furnace is subjected to shell pass of the hairpin heat exchanger through the inlet pipeline 2, and is merged into a medium-pressure cylinder steam inlet pipeline through the outlet pipeline 3 after being heated.

The external reheating bypass and the decoupling reheater 4 form an external bypass reheating module.

The bypass reheating module outside the furnace introduces high-pressure cylinder exhaust steam which originally enters a boiler reheater by using a bypass, and the high-pressure cylinder exhaust steam is converged with the shunted partial hot reheat steam after completing a heated process through the decoupling reheater 4 and enters an intermediate pressure cylinder to do work and generate power.

The flow rate of the decoupling reheater 4 has a large matching range, and can be designed according to high discharge full flow rate or partial flow rate, so as to reduce the equipment cost.

Further included in the system is a reheat cycle line, steam ejector system 10.

The high pressure bypass line 1b is connected to the motive steam inlet a of the steam ejector system 10. A temperature and pressure reducing device is arranged on the high-pressure bypass pipeline 1b, and the main steam after being subjected to temperature and pressure reduction is used as power steam of the steam ejector;

the hot end outlet 1e of the reheater is connected with two pipelines, and one pipeline is connected to the intermediate pressure cylinder through the intermediate pressure cylinder steam inlet pipeline 6. The other path is connected with a suction steam port B of the steam ejector through a reheating circulating pipeline.

Steam from the reheat cycle line is drawn as steam into the steam ejector.

The steam outlet C of the steam ejector is connected to the reheater cold-end inlet 1d via a steam exhaust line 7.

The decoupling reheater 4 is connected in series on the reheating circulating pipeline, the reheating circulating pipeline comprises an inlet pipeline 8 positioned on the upstream side of the decoupling reheater 4 and an outlet pipeline 9 positioned on the downstream side, the inlet pipeline 8 is connected to a tube pass of the decoupling reheater 4, the outlet pipeline 9 is connected to a suction steam port B, superheated steam in the reheating circulating pipeline is used for reheating high-pressure cylinder exhaust steam flowing through a shell pass of the decoupling reheater 4, and the superheated steam in the reheating circulating pipeline becomes low in temperature after passing through the decoupling reheater 4 and enters the suction steam port B of the ejector along the outlet pipeline 9.

A valve is arranged on the inlet pipeline 8. A desuperheater is mounted on the outlet line 9. The outlet line 9 is also connected to a hot external steam supply line 13 for supplying external industrial steam.

The reheat cycle line and the steam ejector constitute a hot reheat steam recycle module. The exhaust steam of the steam ejector ensures that the reheater inlet parameters meet the boiler requirements. Especially when the unit is in the pure decoupling zero operating mode of congealing, can artificially control the temperature that improves the ejector exhaust steam, reduce the exhaust steam flow, reduce the heat absorption capacity of boiler re-heater, optimize afterbody flue operating mode, improve desulfurization and denitration system and the air preheater operating mode when the boiler low-load.

The steam ejector system 10 can adopt a single or a plurality of steam ejectors, the plurality of steam ejectors form a steam ejector group through combination modes such as series connection, parallel connection or series-parallel connection, the adjustment and optimization of parameters such as an ejection ratio and the like are realized, variable working conditions are completed, and nozzles of the steam ejectors adopt fixed nozzles or adjustable nozzles.

The system further comprises an energy storage bypass pipeline 14 and an energy storage reheating module.

The energy storage reheating module is composed of an energy storage heat exchanger 15, a high-temperature molten salt tank 18a and a low-temperature molten salt tank 18 b. The energy storage heat exchanger 15 adopts a shell-and-tube heat exchanger, two ends of a tube pass of the heat exchanger are respectively connected with a high-temperature molten salt tank and a low-temperature molten salt tank, and molten salt flows in the tube pass and exchanges heat with steam introduced in the shell pass of the heat exchanger.

The energy storage reheating module can complete two different steam heat release processes and a steam heating process.

1) Steam exothermal process.

The exhaust pipe of the intermediate pressure cylinder is connected with the inlet pipe of the low pressure cylinder through the communication pipe 22 of the intermediate and low pressure cylinders.

An energy storage bypass pipeline 14 is led out from a reheater hot end outlet 1e and connected to a shell side first inlet of the molten salt heat exchanger. The shell side first outlet is connected to the upstream of the intermediate and low pressure cylinder communicating pipe 22 through the steam supplementing pipe 16.

The energy storage reheating module can realize the peak regulation function under the pure condensation working condition of the unit: at this time, the boiler is operated at the lowest steady combustion (for example, 30% THA), and the steam turbine is operated at the high and medium pressure cylinders (irrespective of the low pressure cylinder) with the minimum steam admission amount (for example, 5% THA), so as to reduce the unit power generation amount as much as possible. At the moment, all the high-pressure cylinder exhaust steam flows through the decoupling reheater, and enters the intermediate pressure cylinder after being heated.

An energy storage bypass pipeline 14 is arranged at a hot end outlet 1e of the reheater and goes to a low-pressure cylinder, an energy storage heat exchanger 15 is arranged in a conveying process, hot reheat steam flows out of a shell pass of the energy storage heat exchanger 15, is cooled, then enters a middle-low pressure cylinder communicating pipe through a pressure reducing valve of a lower peak regulation steam supplementing pipeline 16, then flows into the low-pressure cylinder, and is supplemented with steam for the low-pressure cylinder. With tubes of heat exchangers of fused salt, absorbing and storing hot re-vapours

Can reduce the generated energy as much as possible and store the redundant units

And simultaneously, the steam inlet quantity of the low pressure cylinder is ensured to be larger than the safety flow.

The shell side first outlet is also connected to a reheating cycle outlet pipeline 9 through a reheating cycle steam return pipe 17, and is used for bringing part of heat-exchanged and temperature-reduced steam into the reheating cycle again.

In the steam heat release process, multi-waste heat reheating section steam generated by machine-furnace decoupling enters an energy storage reheater 15 through an energy storage bypass pipeline 14, the steam is divided into two paths after heat release and temperature reduction, one part of the steam is supplemented to a low pressure cylinder to ensure that the low pressure cylinder does not blow air, and the other part of the steam returns to an ejector suction port B to meet the requirement of heat recirculation flow. At the moment, the unit is in an extremely low power generation amount, and even can reach a rotary standby state (0 electric quantity is on line). While being redundant

Is stored in the molten salt.

2) And (4) a steam heating process.

In order to complete the steam heating process, the system constructs a bypass of a medium-low pressure communicating pipe: a shut-off valve is provided in the intermediate and low pressure cylinder communication pipe 22. The intermediate-row reheat circuit 19 is led out from the upstream of the intermediate-low pressure cylinder communicating pipe 22, and is connected to the shell side second inlet of the accumulator heat exchanger 15. The second outlet of the shell side is connected with the downstream of the low-pressure cylinder communicating pipe 22 through an up-peak-regulation steam inlet pipeline 20. When the shutoff valve is in a closed state, the middle-row reheating pipeline 19 and the upper peak-regulating steam inlet pipeline 20 form a bypass of a middle-low pressure communicating pipe.

The steam heating function is realized by leading the middle exhaust steam into an energy storage reheater for heating through a middle exhaust reheating pipeline 19 and leading the middle exhaust steam into a low pressure cylinder through an upper peak-regulating steam inlet pipeline 20.

When the load of the power grid rises again, even when the power plant needs to provide peak output, the valve on the communicating pipe 22 of the medium and low pressure cylinder is closed, the medium exhaust steam firstly enters the energy storage reheater through the medium exhaust reheating pipeline 19 to be heated, and then enters the low pressure cylinder through the upper peak regulation steam inlet pipeline 20. The heat released by the molten salt reheats the centrally-discharged steam, so that the peak regulation function of the thermal power generating unit is realized.

This energy storage reheat module has the function of row's secondary reheat in, does not increase the cold end loss when exothermic, except heat dissipation loss, does not have other

At the expense of even higher efficiency than the battery energy storage.

The lower peak regulation steam supply pipeline 16 and the middle exhaust reheating pipeline 19 can be respectively and independently provided with pipelines, or can be combined into a bidirectional flow pipeline in part of pipe sections, internal steam reversing is carried out based on different working conditions, and holes of a middle and low pressure communicating pipe can be reduced. In order to meet the arrangement requirement of a power plant, the middle-low pressure communicating pipe can be connected with the middle exhaust steam extraction pipeline without opening holes.

The high-temperature molten salt tank 18a can be connected with a power grid 21, electric heating is carried out on the molten salt by utilizing electric energy of the power grid outside or inside the plant, the high-temperature molten salt tank 18a can be provided with a large-capacity electric heater, and valley electricity of the power grid is absorbed, so that the up-down peak regulation space of the power plant is greatly expanded, and the comprehensive service benefit of the thermal power plant is greatly improved.

Example (b):

taking a certain 300MW subcritical unit as an example, the THA main steam quantity of the unit is 928t, and the output is 300MW.

The system operating parameters are shown in table 1 below:

TABLE 1

When the system is operated and regulated, the following four typical working conditions are provided:

operating condition 1): the boiler 100%.

Working condition 2): the boiler is 100 percent, the steam turbine is 20 percent, and the heat supply and steam extraction capacity of the system is outstanding.

Working condition 3): when the boiler is in stable combustion load (30 percent THA working condition), the unit normally generates electricity and operates when the load is extremely low under the pure coagulation working condition, and the stored energy is subjected to down-peak regulation.

Operating condition 4): the furnaces are all at 100% tha conditions, the grid requires maximum peak-to-peak capacity (superissue), and the discharge can be up-regulated.

When the machine furnace is decoupled and supplies heat to the outside, such as working condition 1) and working condition 2).

Firstly, the bypass reheating module outside the furnace is started, part of high exhaust enters the decoupling reheater 4, and the high exhaust is heated and then heated to return to the hot reheat pipeline to enter the intermediate pressure cylinder.

The hot re-steam recirculation module is then activated. The through flow required by a boiler reheater is realized by injecting heat recirculation through a steam ejector: and part of the reheat hot section steam goes to the intermediate pressure cylinder, and part of the reheat hot section steam enters a recirculation pipeline through an inlet pipeline 8 and enters the decoupling reheater 4 to heat the introduced part of the high-level exhaust. Then spraying water in proper amount to reduce temperature. The power steam of the ejector is used for ejecting and sucking low-pressure steam, and the requirement of a boiler reheater is met.

At the moment, the front and rear hearths of the boiler are balanced, and the high and medium pressure cylinders of the steam turbine are also in a balanced state.

At the moment, the high-discharge pipeline has redundant steam, and the redundant hot re-steam in the hot re-circulation pipeline can be used for supplying heat (steam) to the outside.

Further, if the boiler load is not changed, the steam engine load is reduced. The decoupling range of the machine furnace is continuously enlarged, the steam inlet quantity of the steam turbine is continuously reduced, the external steam supply capacity of the system is increased, and sufficient industrial steam can be supplied to the outside.

When the unit operates in the pure condensing working condition, such as working condition 3).

When the power grid needs to carry out peak shaving, the boiler is reduced to the lowest stable combustion load (30%), the steam turbine operates according to the minimum steam inlet quantity, the hot reheat steam after the decoupling heat exchanger is exhausted is sucked by the ejector and then brought into hot recirculation, and the redundant hot reheat steam enters the energy storage reheating module to store energy and supplement steam for the low-pressure cylinder, so that the low-pressure cylinder does not blast. At the moment, the generating capacity is reduced by the unit through manual control, and meanwhile, the steam temperature of the reheating and cooling section is increased, so that the working condition of a tail flue of the boiler is optimized. And will be effective

Stored in molten salt.

And during peak load adjustment, the energy storage reheating module can be electrically heated by using the electric energy of an off-plant or in-plant power grid, so that the valley electricity of the power grid is consumed.

When the grid requires the plant to provide a peak output, as in condition 4).

When the power grid needs power plant supply pointsWhen the peak power is applied, the valve on the middle and low pressure cylinder communicating pipe 22 is closed, the middle exhaust steam enters the energy storage reheating module to be heated and reheated and enters the low pressure cylinder to do work, and therefore the peak regulation function on the thermal power generating unit is achieved. The heat-releasing process is a reheating process and is originally stored

Can be converted into electricity. Stored by energy-storage reheating module

The low-pressure cylinder is heated to enter steam in the peak load section of the power grid, and the low-pressure cylinder is reheated, so that the peak regulation (super-generation) function of the unit can be realized.

During actual operation regulation and control, when the unit is in a cogeneration mode and needs to reduce peak, the unit operates in a decoupling and energy storage heat absorption mode: high bypass opening, putting a decoupling reheater and an ejector group into operation, and after thermal recycling is established, a boiler can be in high load and a front hearth and a rear hearth are balanced, and a steam turbine is in low load and high-medium pressure cylinder thrust balance; at the moment, the energy of the hot section of the boiler reheater is much abundant, and the redundant energy released to the decoupling reheater and the energy storage reheater is supplied to the outside for heat (steam).

When the unit is in pure condensing condition and needs to adjust peak, the unit operates in decoupling and energy storage heat absorption mode: the boiler operates at the lowest stable combustion load, the steam turbine enters steam according to the minimum allowable steam inlet quantity of the high and medium pressure cylinders, steam in the hot section of the boiler reheater does not flow to the medium pressure cylinder any more, the steam is divided into two parts, one part of the steam is sent to the decoupling reheater, and then the whole steam is sucked by the ejector group to realize hot recirculation; the other path enters an energy storage reheater, and after being cooled, all the energy storage reheater enters a low pressure cylinder, so that the flow of the low pressure cylinder is increased, and no blast is ensured;

when the unit needs to be peaked up (whether cogeneration or straight condensing), the unit is not decoupled and operates in an energy storage and heat release manner: the high bypass, decoupling reheater and ejector are all out of operation; and the communication valve is closed, and the exhaust steam of the intermediate pressure cylinder firstly flows through the energy storage reheater, is heated and then enters the low pressure cylinder, which is equivalent to the process that the low pressure cylinder enters the steam to perform reheating.

From table 1 above, the system is significant for pure coagulation conditions: the energy storage module of the system has extremely high energy efficiency, and the cost performance of the energy storage heat exchanger is superior to that of the electric heater, so the system has extremely high economy.

Bypass reheating module outside stove, hot steam recirculation module, energy storage reheating module in this application system cooperate each other, realize powerful thermal power flexibility function: the device can be used for large-parameter heat (steam) supply working conditions and can also realize the great peak regulation capacity of the unit when being used for pure condensation working conditions. In the system, the steam ejector group does not extract steam from the high-pressure cylinder, so that the dynamic safety problem of the steam turbine is greatly simplified, and the engineering risk is greatly reduced.

The system has the obvious advantages that:

1) Existing METE (utilizing main steam to direct high exhaust back to reheater) systems have one limiting capability: as the turbine to boiler load differential becomes larger and larger, the injector bank step-up ratio n continues to rise, with an upper limit (typically 1.5 times safer). Therefore, the METE system is difficult to decouple in all working conditions, and the high bypass in the system does not return to a boiler reheater, so that the problem does not exist.

2) The behaviour of the ejector group of the BERL system is much better than that of the METE system: the BERL system only needs to boost the hot outlet pressure to the inlet pressure, the boost ratio is low and is a fixed value (< 1.2), greatly simplifying injector bank selection.

3) The monitoring of the DCS on the unit becomes simple: the high exhaust of the steam turbine is superior to that of a steam turbine, and the high exhaust does not need to return to a boiler reheater, so that the greatest difficulty of decoupling the turbine and the boiler is overcome. When the load rate of the power grid to the unit is too low and the decoupling of the unit furnace is needed, only the opening degrees of the high side valve, the thermal pressure relief valve and the flow regulating valve are needed to be adjusted; the load of the boiler is adjusted in a follow-up mode, the flow variable working condition of the ejector is only changed, the process system does not involve too many safety problems, and the safety monitoring difficulty of the DCS on the unit is lower.

4) The model selection design of the ejector group is simpler: the working condition of the injector group becomes excellent, so that the matching of the injection parameters n-u becomes simple. Because the boosting ratio becomes narrower than the variable working condition, only the variable working condition of the flow needs to be considered, the variable working condition of the injector group is changed from multi-dimension to single-dimension, and the design and the model selection are simpler.

5) The steam supply capacity of the high side becomes strong: because the working condition of the ejector group becomes excellent, the consumption of the power steam becomes small, and the steam supply flow at the high side is obviously improved.

6) The steam supply pressure of the hot steam is not limited by the load rate of the boiler: the heat in the new system is physically isolated from the high-level exhaust, the pressure of the heat is not limited by the high-level exhaust, the heat is in closed-loop self-circulation, and the pressure rise of the ejector group only needs to compensate the on-way resistance loss of the heat recirculation (generally, the pressure loss of the boiler reheater is 10% of the heat, namely, the ejector group n =1.11 can realize the recirculation, and the pressure loss of the decoupling reheater is considered and cannot exceed 1.2). At this point, the reheater pressure is no longer constrained by the boiler-to-boiler decoupling relationship and may even be higher than the thermal repressurization pressure for the boiler load rate (e.g., the boiler is operated at 50% THA, the steam turbine is operated at 20% and the thermal repressurization pressure may still be set at 3.5MPa for the boiler at 100% THA). This means that the pressure level of the heat supplying steam to the outside can be full pressure, so that the steam supplying radius of the power plant is greatly expanded, and the market development and application are facilitated.

The system also has obvious advantages of safety, energy conservation and environmental protection:

compared with the existing system, the system is transformed into harmless transformation: 1) The boiler and the steam turbine body do not need to be transformed, and only the pipeline needs to be modified. 2) The system is not transformed irreversibly, and can be switched to a pre-transformation state through a system shutoff door; 3) The ejector, the decoupling reheater and the energy storage reheater adopted by the system have intrinsic safety;

the specially designed 'energy storage reheater' enables the molten salt energy storage to have extremely high efficiency: decoupling of surplus machine-furnace at trough section of electric network

The steam is stored and supplemented to the low-pressure cylinder steam inlet in the peak period, the low-pressure steam inlet is reheated, and the low-pressure cylinder output is improved. Because the cold end increment is not generated in the heat release process, the efficiency is equal to that of 'unit secondary reheating', and therefore the system

The efficiency is extremely high.

If the molten salt system is enlarged in scale and provided with an electrode heating device, a large amount of valley electricity in the power grid can be consumed, and the heat release process of the system is

The efficiency is extremely high, almost can compare favourably with chemical batteries, and the cost performance is far higher than that of the chemical batteries.

Finally, it should be noted that: although the present invention has been described in detail, it will be apparent to those skilled in the art that changes may be made in the above embodiments, and equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Machine-furnace decoupling and low realization by adopting reheating outside furnace

the method is characterized in that a high-pressure cylinder steam exhaust pipeline is connected to a cold end inlet of a boiler reheater; the hot end outlet of the reheater is connected with a steam turbine intermediate pressure cylinder through an intermediate pressure cylinder steam inlet pipeline;

a steam ejector system is arranged in the reheating circulation pipeline; the high-pressure bypass pipeline is connected with a power steam inlet of the steam ejector system; the reheating circulation pipeline is connected with a suction steam port of the steam ejector system; the steam exhaust port of the steam ejector system is connected with the cold end inlet of the reheater.

2. The method as claimed in claim 1 for achieving machine-furnace decoupling and low temperature with external reheating

The power loss and energy storage thermoelectric system is characterized in that a steam ejector system adopts a single or a plurality of steam ejectors; the plurality of steam ejectors form a steam ejector group in a series connection, parallel connection or series-parallel connection combination mode.

3. The method as claimed in claim 1 for achieving machine-furnace decoupling and low temperature with external reheating

The energy-loss-storage thermoelectric system is characterized by comprising an energy-storage reheating module, wherein the energy-storage reheating module consists of an energy-storage heat exchanger, a high-temperature molten salt tank and a low-temperature molten salt tank; an energy storage bypass pipeline is led out from a hot end outlet of the reheater and connected to a first inlet of the energy storage heat exchanger; a first outlet of the energy storage heat exchanger is connected to the low pressure cylinder through a steam supplementing pipeline; the fused salt in the energy storage heat exchanger exchanges heat with the introduced steam.

4. The method as claimed in claim 3 for achieving machine-to-furnace decoupling and low-to-furnace reheating with external reheating

And the energy-loss energy-storage thermoelectric system is characterized in that the first outlet of the energy-storage heat exchanger is also connected to a reheating circulation pipeline through a reheating circulation steam return pipe.

5. The use furnace of claim 3Machine furnace decoupling and low realization by external reheating

The power loss and energy storage thermoelectric system is characterized in that the exhaust steam of the intermediate pressure cylinder is connected to a second inlet of the energy storage heat exchanger through an intermediate row reheating pipeline; and a second outlet of the energy storage heat exchanger is connected to the low pressure cylinder through a steam inlet pipeline.

6. The method as claimed in claim 3 for achieving machine-to-furnace decoupling and low-to-furnace reheating with external reheating

The loss energy storage thermoelectric system is characterized in that the high-temperature molten salt tank is also connected with a power grid, and the electric energy of the power grid outside or inside the plant is utilized to electrically heat the molten salt.

7. The method of claim 1 for achieving machine-to-furnace decoupling and low-to-furnace reheating with external reheating

The loss energy storage thermoelectric system is characterized in that a hot section pressure regulating assembly is arranged on a steam inlet pipeline of the intermediate pressure cylinder, the hot section pressure regulating assembly has a pressure building and regulating function and controls target pressure required by a hot end of a reheater, and the actual pressure of reheated steam is higher than the reheat pressure corresponding to the load of a boiler.

8. The method as claimed in claim 7 for achieving machine-to-furnace decoupling and low through external reheating

The energy-loss-storage thermoelectric system is characterized in that an external reheating bypass is connected out from a high-pressure cylinder steam exhaust pipeline, and the external reheating bypass and a medium-pressure cylinder steam inlet pipeline are converged at the downstream of a hot section pressure regulating assembly.

9. The method as claimed in claim 1 for achieving machine-furnace decoupling and low temperature with external reheating

The high-pressure bypass pipeline is further connected with a high-pressure bypass external steam supply pipeline to externally provide industrial steam, the high-pressure cylinder steam exhaust pipeline is connected with a high-pressure exhaust external steam supply pipeline to externally provide industrial steam, and the reheating circulation pipeline is connected with heat and then externally provides industrial steam for the steam supply pipeline.

10. The method as claimed in claim 1 for achieving machine-furnace decoupling and low temperature with external reheating

The high-pressure bypass pipeline is further connected with a high-side interconnection pipe of an adjacent unit, and the two adjacent units are interconnected through the high-side interconnection pipe of the adjacent unit and used for interconnection and assistance in steam supply during decoupling operation of the boiler.