A heat storage peak regulation system based on desalted water tank and its operation method

Abstract

The present invention discloses a heat storage and peak-shaving system based on a desalted water tank and an operating method, comprising an existing steam-water system of a steam turbine unit, reused equipment, and an additional system; by connecting the condensate pipes at the outlets of multiple low-pressure heaters to a first desalted water tank, connecting the outlet pipe of the first desalted water tank to the condensate pipe at the inlet of a deaerator, and adding a hot water delivery pump to the outlet pipe of the first desalted water tank, the function of storing or delivering hot water to the condensate pipe at the inlet of the deaerator is achieved. By connecting the outlet pipe of the condensate pump to a second desalted water tank, connecting the outlet pipe of the second desalted water tank to the condenser hot well, and adding a cold water delivery pump to the outlet pipe of the second desalted water tank, the function of controlling the condensate flow rate and further regulating the power generation load of the unit is achieved. The purpose of being able to increase the output of the unit in a short time is achieved, especially for units whose output has not reached the rated value, the power generation capacity of the unit can be significantly improved.

Description

Technical Field

[0001] The present invention belongs to the field of thermal power generation, and in particular relates to a heat storage peak regulation system based on a desalted water tank and an operation method thereof. Background Art

[0002] In order to ensure the safe and stable operation of the power grid system while the new energy power generation system is developing rapidly, higher requirements are objectively placed on the peak-shaving capacity of traditional thermal power units.

[0003] In order to enable conventional thermal power units to have stronger deep peak-shaving capabilities, foreign research institutions are exploring the flexibility transformation and operation technology of thermal power units. For example, Denmark is the main country in Europe for thermal power flexibility transformation. Its thermal power flexibility transformation is a market-driven and gradually in-depth process, and is also an important part of its power system transformation.

[0004] Technologies currently being promoted include low-load stable combustion for boilers and thermoelectric decoupling technology, which is being explored for heating units. Low-load stable combustion is subject to boiler safety restrictions, limiting the minimum operating load. Thermoelectric decoupling requires a large number of heat users near the power plant.

[0005] Therefore, for the units that have already adopted boiler low-load stable combustion technology and thermoelectric decoupling technology to achieve deep peak regulation, research on how to further tap the peak regulation capacity of the units, especially how to maximize the use of existing equipment or achieve further deep peak regulation with the lowest investment, is of great significance to the fate of traditional thermal power generation and energy strategic planning. Summary of the Invention

[0006] The purpose of the present invention is to provide a heat storage peak-shaving system and operation method based on a desalted water tank. By slightly modifying and utilizing the existing desalted water tank, the unit can have the re-peaking capability under deep peak-shaving conditions to a certain extent.

[0007] The present invention is achieved by adopting the following technical solutions:

[0008] A heat storage peak-shaving system based on a desalted water tank comprises a steam-water system of a steam turbine unit, reused equipment, and an additional system; wherein the steam-water system of the steam turbine unit comprises a deaerator and a condenser; the reused equipment comprises a first desalted water tank and a second desalted water tank; the additional system comprises a connecting pipe; and a valve group is provided on the connecting pipe.

[0009] A water supply main pipe is provided from the condensate pipe of the steam-water system of the steam turbine unit to the water inlet of the first desalted water tank; a condensate pipe is provided from the water outlet of the first desalted water tank to the inlet of the deaerator;

[0010] A first water supply branch pipe is provided from the outlet condensate pipe of the secondary low-pressure heater of the steam-water system of the steam turbine unit to the first desalted water tank; a second water supply branch pipe is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank; a third water supply branch pipe is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank; a fourth water supply branch pipe is provided from the outlet condensate pipe of the final low-pressure heater to the first desalted water tank;

[0011] A water outlet pipe is provided from the second desalted water tank to the condenser hot well; a water supply pipe is provided from the condensate pump outlet to the second desalted water tank.

[0012] As a further improvement of the present invention, a hole is opened and a tee is added on the condensate water pipe at the outlet of the last-stage low-pressure heater to connect the fourth water supply branch pipe, and the first water supply branch pipe valve group is installed on the fourth water supply branch pipe; a hole is opened and a tee is added on the condensate water pipe at the outlet of the second-last-stage low-pressure heater to connect the first water supply branch pipe, and the second water supply branch pipe valve group is installed on the first water supply branch pipe; a hole is opened and a tee is added on the condensate water pipe at the outlet of the second-second-last-stage low-pressure heater to connect the second water supply branch pipe, and the third water supply branch pipe valve group is installed on the second water supply branch pipe; a hole is opened and a tee is added on the condensate water pipe at the outlet of the second-second-last-stage low-pressure heater to connect the third water supply branch pipe, and the fourth water supply branch pipe valve group is installed on the third water supply branch pipe.

[0013] As a further improvement of the present invention, the first water supply branch pipe, the second water supply branch pipe, the third water supply branch pipe and the fourth water supply branch pipe are merged into a water supply main pipe, and a water supply main pipe valve group is installed on the pipe.

[0014] As a further improvement of the present invention, the water outlet pipe is provided with a water outlet pipe valve group; the water supply pipe is provided with a water supply pipe valve group; and the condensate water pipe is provided with a condensate water pipe valve group.

[0015] As a further improvement of the present invention, a valve group is installed on the downstream condensate pipeline from the condensate pump outlet to the pipeline water supply three-way point of the steam-water system of the steam turbine unit.

[0016] As a further improvement of the present invention, a valve group and a hot water delivery pump are installed on the condensate pipeline; and a valve group and a cold water delivery pump are installed on the outlet pipeline.

[0017] As a further improvement of the present invention, an insulation layer is added to the outside of the first desalted water tank and the second desalted water tank, and the insulation layer can meet the requirement that the water temperature of the desalted water tank does not drop by more than 4°C when the tank is full and left standing for 2 hours.

[0018] As a further improvement of the present invention, the steam-water system of the steam turbine unit further includes a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder; the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder coaxially drive a generator to generate electricity.

[0019] An operating method of a heat storage peak regulation system based on a desalted water tank, comprising a heat storage peak regulation operating mode and an energy release operating mode;

[0020] A. Thermal storage peak load regulation operation modes include:

[0021] The second desalted water tank is filled with cold water, and the first desalted water tank is empty;

[0022] According to the outlet water temperature of each level of low-pressure heater, the water temperature of the water supply main pipe is controlled to not exceed 97℃ by using the opening of the valve group;

[0023] According to the peak load depth and peak load duration, the flow rate adjustment range of the water supply main pipe is t / h~F cp_out , where F cp_out is the condensate flow rate under the original maximum deep adjustment load of the steam turbine;

[0024] During heat storage, cold water from the second desalted water tank is continuously injected into the condenser hot well through the cold water delivery pump, and the water level in the second desalted water tank continuously decreases until the liquid level reaches zero; hot water flows into the first desalted water tank through the pipeline, and the water level in the tank continuously rises until the liquid level reaches the upper limit, and the water temperature is maintained at 97°C;

[0025] When the grid load demand is low and the unit needs to be in deep peak-shaving operation conditions, a large amount of 97°C condensate is stored from the condensate pipeline to the first desalted water tank, which increases the steam extraction of the low-pressure cylinder of the turbine, thereby reducing the unit load; cold water from the second desalted water tank is continuously injected into the condenser, increasing the condensate flow through the low-pressure heater.

[0026] B. Energy release reset operation mode and implementation function are:

[0027] Before the energy is released, the second desalted water tank is empty and the first desalted water tank is filled with hot water;

[0028] The hot water in the first desalted water tank enters the deaerator inlet condensate pipe through the condensate pipe;

[0029] The condensate at the outlet of the condensate pump enters the second desalted water tank through the water supply pipe;

[0030] When the grid load does not require the unit to perform deep peak regulation and the unit output meets the grid requirements, the unit will release energy at an appropriate time and operate in this energy release reset mode; hot water from the first desalted water tank will continuously enter the condensate system until the liquid level reaches zero, and cold water will continuously be injected into the second desalted water tank until the liquid level reaches the upper limit;

[0031] When the unit's power output is insufficient in the summer, the unit also operates in the energy release and reset operation mode, increasing the unit's output by controlling the valve group opening and transmission output.

[0032] As a further improvement of the present invention, the method for opening the valve group in the thermal storage peak regulation operation mode is:

[0033] a) When T P4 When the temperature is less than 97℃, only the first water supply branch pipe valve group is opened; the second water supply branch pipe valve group, the third water supply branch pipe valve group, and the fourth water supply branch pipe valve group are closed;

[0034] b) When T P4 ≥97℃ and T<97℃, open the first and second water supply branch pipe valve groups, and close the third and fourth water supply branch pipe valve groups;

[0035] c) When T P1 ≥97℃ and T<97℃, open the second and third water supply branch pipe valve groups, and close the first and fourth water supply branch pipe valve groups;

[0036] d) When T P2 ≥97℃, and T<97℃, open the third water supply branch pipe valve group and the fourth water supply branch pipe valve group, and close the first water supply branch pipe valve group and the fourth water supply branch pipe valve group.

[0037] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0038] The present invention utilizes the desalted water tanks of a power plant, where the source of the reused equipment is multiple desalted water tanks, by appropriately modifying the desalted water tanks without affecting their original functionality. The system connection and method of the present invention redevelops and reuses the existing desalted water tanks without affecting their functionality, saving the significant investment required to construct separate hot water storage tanks and enabling the units to achieve re-peaking under deep peaking conditions. The system connection and method of the present invention also allows for a short-term boost in unit output when the power grid is insufficient in the summer, significantly improving the generating capacity of units whose output has not yet reached its rated value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings:

[0040] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0041] Description of reference numerals:

[0042] A first desalted water tank 1; a second desalted water tank 2; a hot water delivery pump 3; and a cold water delivery pump 4.

[0043] The first water supply branch pipe valve group V1; the second water supply branch pipe valve group V2; the third water supply branch pipe valve group V3; the fourth water supply branch pipe valve group V4; the condensate pipeline valve group V5; the outlet pipeline valve group V6; the water supply pipeline valve group V7; the main pipe pipeline valve group V8; the water supply main pipe valve group V9.

[0044] First water supply branch pipe P1; second water supply branch pipe P2; third water supply branch pipe P3; fourth water supply branch pipe P4; water supply main pipe P5; water outlet pipe P6; water supply pipe P7; condensate pipe P8. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0046] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an element centered thereon. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an element centered thereon. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] like Figure 1 As shown, the present invention is a heat storage peak regulation system based on a desalted water tank, including a steam-water system of a steam turbine unit, reuse equipment and an additional system;

[0049] The steam-water system of the steam turbine unit includes a deaerator and a condenser; the reused equipment includes a first desalted water tank 1 and a second desalted water tank 2; the additional system includes a connecting pipe; a valve group is provided on the connecting pipe;

[0050] A water supply main pipe P5 is provided from the condensate pipe of the steam-water system of the steam turbine unit to the water inlet of the first desalted water tank 1; a condensate pipe P8 is provided from the water outlet of the first desalted water tank 1 to the inlet of the deaerator;

[0051] A first water supply branch pipe P1 is provided from the outlet condensate pipe of the secondary low-pressure heater of the steam-water system of the steam turbine to the first desalted water tank 1; a second water supply branch pipe P2 is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank 1; a third water supply branch pipe P3 is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank 1; a fourth water supply branch pipe P4 is provided from the outlet condensate pipe of the final low-pressure heater to the first desalted water tank 1;

[0052] A water outlet pipe P6 is provided from the second desalted water tank 2 to the condenser hot well; a water supply pipe P7 is provided from the condensate pump outlet to the second desalted water tank 2.

[0053] The additional system includes valve blocks, equipment, and connecting pipes. By connecting the condensate pipes at the outlets of multiple low-pressure heaters to the first desalted water tank 1, connecting the outlet pipe of the first desalted water tank 1 to the condensate pipe at the inlet of the deaerator, and adding a hot water transfer pump to the outlet pipe of the first desalted water tank 1, hot water can be stored or transferred to the condensate pipe at the inlet of the deaerator. By connecting the condensate pump outlet pipe to the second desalted water tank 2, connecting the outlet pipe of the second desalted water tank 2 to the condenser hot well, and adding a cold water transfer pump to the outlet pipe of the second desalted water tank 2, condensate flow can be controlled, further regulating the unit's power generation load. This method, without affecting the original function of the desalted water tank equipment, redevelops and reuses the functions of the existing equipment, enabling the unit to achieve re-peaking under deep peak-shaving conditions. Furthermore, in the summer, when the grid output is insufficient, it can temporarily increase the unit's output, significantly improving the unit's power generation capacity, especially for units whose output does not reach the rated value.

[0054] The present invention will be described in detail below with reference to the accompanying drawings.

[0055] like Figure 1 The heat storage peak regulation system based on the desalted water tank shown includes a steam-water system of a steam turbine unit, reused equipment and an additional system; wherein the additional system includes a valve group, equipment and connecting pipes.

[0056] The reused equipment includes the first desalted water tank 1 and the second desalted water tank 2. The reused equipment is sourced from power plants with multiple desalted water tanks. These tanks are then appropriately modified without affecting their original functionality. The modifications involve adding insulation to the exterior of the first and second desalted water tanks 1 and 2 to ensure that the desalted water temperature does not drop by more than 4°C after four hours of standing, even when the tanks are full.

[0057] The additional equipment includes: a hot water delivery pump 3; a cold water delivery pump 4.

[0058] Among them, the additional valve group includes:

[0059] V1 is the water supply branch pipe valve group from the outlet of the last-stage low-pressure heater to the first desalted water tank 1; V2 is the water supply branch pipe valve group from the outlet of the second-last-stage low-pressure heater to the first desalted water tank 1; V3 is the water supply branch pipe valve group from the outlet of the second-second-last-stage low-pressure heater to the first desalted water tank 1; V4 is the water supply branch pipe valve group from the outlet of the second-second-last-stage low-pressure heater to the first desalted water tank 1; V5 is the condensate pipe valve group from the first desalted water tank 1 to the deaerator inlet; V6 is the water outlet pipe valve group from the second desalted water tank 2 to the condenser hot well; V7 is the water supply pipe valve group from the condensate pump outlet to the second desalted water tank 2; V8 is the condensate main pipe pipe valve group; V9 is the water supply main pipe valve group from condensate to the first desalted water tank 1.

[0060] The V1, V2, V3, V4, and V7 valve groups have pressure reducing, shutoff, and flow adjustment functions; the V5, V6, V8, and V9 have shutoff and flow adjustment functions.

[0061] The additional pipelines include:

[0062] P1 is the water supply branch pipe from the outlet of the secondary low-pressure heater to the first desalted water tank 1; P2 is the water supply branch pipe from the outlet of the secondary low-pressure heater to the first desalted water tank 1; P3 is the water supply branch pipe from the outlet of the secondary low-pressure heater to the first desalted water tank 1; P4 is the water supply branch pipe from the outlet of the final low-pressure heater to the first desalted water tank 1; P5 is the water supply main pipe from the condensate pipe to the first desalted water tank 1; P6 is the water outlet pipe from the second desalted water tank 2 to the condenser hot well; P7 is the water supply pipe from the condensate pump outlet to the second desalted water tank 2; P8 is the condensate pipe from the outlet of the first desalted water tank 1 to the inlet of the deaerator.

[0063] like Figure 1 As shown in the figure, the connection method between the additional system, the reused equipment and the steam-water system of the existing steam turbine unit is:

[0064] A hole is drilled and a tee is added on the condensate water pipe at the outlet of the last-stage low-pressure heater to connect it to the fourth water supply branch pipe P4, and the first water supply branch pipe valve group V1 is installed on the fourth water supply branch pipe P4; a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-last-stage low-pressure heater to connect it to the first water supply branch pipe P1, and the second water supply branch pipe valve group V2 is installed on the first water supply branch pipe P1; a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-second-last-stage low-pressure heater to connect it to the second water supply branch pipe P2, and the third water supply branch pipe valve group V3 is installed on the second water supply branch pipe P2; a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-second-last-stage low-pressure heater to connect it to the third water supply branch pipe P3, and the fourth water supply branch pipe valve group V4 is installed on the third water supply branch pipe P3. The first water supply branch pipe P1, the second water supply branch pipe P2, the third water supply branch pipe P3, and the fourth water supply branch pipe P4 converge into the water supply main pipe P5. The other end of the water supply main pipe P5 is connected to the first desalted water tank 1, and the water supply main pipe valve group V9 is installed on the water supply main pipe P5.

[0065] A condensate pipe P8 is installed from the first desalted water tank 1 to connect the first desalted water tank 1 and the deaerator inlet condensate pipe. A condensate pipe valve group V5 and a hot water delivery pump 3 are installed on the condensate pipe P8.

[0066] Install the outlet pipe P6 from the second desalted water tank 2 to connect the second desalted water tank 2 and the condenser hot well. Install the outlet pipe valve group V6 and the cold water delivery pump 4 on the outlet pipe P6;

[0067] Drill a hole in the condensate pipe at the condensate pump outlet and add a tee to lead out the water supply pipe P7, which is connected to the second desalted water tank 2. Install the water supply pipe valve group V7 on the water supply pipe P7;

[0068] Install the main pipe valve group V8 on the downstream condensate pipe from the condensate pump outlet to the water supply tee point P7 of the water supply pipe.

[0069] The operation modes of the system include heat storage peak regulation operation mode and energy release operation mode. The specific operation methods are as follows:

[0070] A. Thermal storage peak load regulation operation mode and its functions are as follows:

[0071] (1) The main status of the system equipment is: valve groups V1, V2, V3, V4, V6, V8, and V9 are open, valve groups V5 and V7 are closed, and the main pipe valve group V8 is in automatic state; the hot water delivery pump 3 is closed, and the cold water delivery pump 4 is closed; before starting heat storage, the second desalted water tank 2 is filled with cold water, and the first desalted water tank 1 is empty;

[0072] (2) According to the outlet water temperature of each level of low-pressure heater, use the opening of valve groups V1, V2, V3, and V4 to control the water temperature of the water supply main pipe P5 to be close to but less than 97°C. The opening principle of valve groups V1, V2, V3, and V4 is:

[0073] a) When T P4 When the temperature is less than 97℃, only V1 is turned on, and V2, V3 and V4 are turned off;

[0074] b) When T P4 ≥97℃, and T P1 <97℃, open V1 and V2, and close V3 and V4;

[0075] c) When T P1 ≥97℃, and T P2 <97℃, open V2 and V3, and close V1 and V4;

[0076] d) When T P2 ≥97℃, and T P3 <97℃, turn on V3 and V4, and close V1 and V2.

[0077] (3) According to the peak load depth and peak load duration, the flow rate adjustment range of P5 pipeline is 0t / h~F cp_out , where F cp_out is the condensate flow rate under the original maximum deep adjustment load of the steam turbine;

[0078] (4) The system is in operation as follows: during heat storage, cold water from the second desalted water tank 2 is continuously injected into the condenser hot well via the cold water delivery pump 4, and the water level in the second desalted water tank 2 is continuously reduced until the liquid level reaches zero; hot water flows into the first desalted water tank 1 via the P5 pipe, and the water level in the tank is continuously increased until the liquid level reaches the upper limit, and the water temperature is maintained at approximately 97°C;

[0079] (5) System operation conditions and implementation functions: When the grid load demand is low and the unit needs to be in deep peak-shaving operation, in order to further reduce the peak-shaving depth of the unit, the system operates in this heat storage peak-shaving mode. Since a large amount of 97°C condensate is stored from the condensate pipeline to the first desalted water tank 1, the steam extraction of the low-pressure cylinder of the turbine is increased, thereby reducing the load of the unit; at the same time, cold water from the second desalted water tank 2 is continuously injected into the condenser, increasing the condensate flow through the low-pressure heater, thereby significantly increasing the steam extraction of the deaerator, further reducing the operating load of the unit.

[0080] B. Energy release reset operation mode and implementation function are:

[0081] (1) The main status of the system equipment is: valve groups V5 and V7 are open, valve groups V1, V2, V3, V4, V6, and V9 are closed, and valve group V8 is in automatic state; hot water delivery pump 3 is turned on and cold water delivery pump 4 is turned off; before starting to release energy, the second desalted water tank 2 is empty and the first desalted water tank 1 is filled with hot water;

[0082] (2) The hot water in the first desalted water tank 1 enters the deaerator inlet condensate pipe through the condensate pipe P8 under the operation of the hot water delivery pump 3;

[0083] (3) The condensate at the outlet of the condensate pump enters the second desalted water tank 2 through the water supply pipe P7;

[0084] (4) System operation conditions and implementation functions:

[0085] 1) When the grid load does not require the unit to perform deep peak shaving and the unit output meets the grid's requirements, the unit selects an opportunity to release energy in preparation for the next peak shaving period. The unit operates in this energy release reset mode. Hot water from the first desalted water tank 1 continuously enters the condensate system until the liquid level reaches zero, and cold water is continuously added to the second desalted water tank 2 until the liquid level reaches the upper limit. The entire system is ready for the unit to operate in thermal storage peak shaving mode again.

[0086] 2) When the unit's power output is insufficient in the summer, the unit also operates in the energy release and reset operation mode. By controlling the opening of the V5 and V7 valve groups and the output of the hot water delivery pump 3, the unit's output can be significantly increased in a short period of time, especially for those units whose output has not reached the rated value, which can significantly improve the unit's power generation capacity.

[0087] Table 1 is a comparison of the operating states of the main valve groups and equipment of the system under the two operating modes of the present invention.

[0088] Table 1 Operating status of main valve groups and equipment in the system under two operating modes

[0089]

[0090] Example:

[0091] Taking a 320MW subcritical unit as an example, we performed calculations and statistical analysis of its operating performance after retrofitting using the technical solution of the present invention. As shown in Table 2, the original unit's rated load was 320MW, its rated main steam flow was 921t / h, its maximum deep regulation load was 110.367MW, and its deep peak load rate was 35%. At 35% load, the original water temperature at the outlet of the final-stage LP heater was 116.5°C, and the water temperature at the outlet of the next-final-stage LP heater was 80.9°C.

[0092] The power plant where the unit is located has multiple units and eight 3,000-ton desalted water tanks. Two of these tanks were retrofitted according to the technical solution of this invention. After the retrofit, the system can operate in both thermal storage and peak-shaving modes, as well as energy release and load-increasing modes.

[0093] When the unit is in the heat storage peak-shaving operation mode, the condensate temperature at the outlet of the last stage low-pressure heater in the heat storage peak-shaving operation mode is 99.5℃, the condensate temperature at the outlet of the next last stage low-pressure heater is 69.4℃, the condensate injection flow rate to the desalted water tank for heat storage is 750t / h, the unit load after re-peaking is 103.296MW, the unit load is reduced by 7.071MW, and the re-peaking load is 2.21%. The unit can continuously peak-shave for 4 hours in the heat storage peak-shaving operation mode.

[0094] When the unit is in the energy release and load increase operation mode, with the main steam flow rate of the unit maintained at the same as the rated load at 921t / h, the water injection flow rate from the desalted water tank to the condensate is 673t / h, and the unit load reaches 324.628MW. With the main steam flow rate unchanged, the unit load increases by 4.628MW compared with the original unit rated load, a relative increase of 1.45%. The unit can operate continuously for 4.8 hours in the energy release and load increase operation mode.

[0095] Table 2 Statistical data of peak load regulation capability and operating parameters of units under two conditions in the example

[0096]

[0097] As described above, by utilizing the method of the present invention, the existing functions of the desalting water tank equipment are redeveloped and reused, without affecting the existing functions of the desalting water tank equipment, thereby saving the huge investment cost of building a separate hot water storage tank, and enabling the unit to achieve the re-peaking function under deep peak-shaving conditions; in addition, when the power grid output is insufficient in the summer, the purpose of temporarily increasing the unit output is achieved, especially for those units whose output has not reached the rated value, which can significantly improve the power generation capacity of the unit.

Claims

1. An operating method of a heat storage peak regulation system based on a desalted water tank, characterized in that: It includes a steam-water system of a steam turbine unit, reused equipment and an additional system; wherein the steam-water system of the steam turbine unit includes a deaerator and a condenser; the reused equipment includes a first desalted water tank (1) and a second desalted water tank (2); the additional system includes a connecting pipe; a valve group is provided on the connecting pipe; A water supply main pipe (P5) is provided from the condensate pipe of the steam-water system of the steam turbine unit to the water inlet of the first desalted water tank (1); a condensate pipe (P8) is provided from the water outlet of the first desalted water tank (1) to the inlet of the deaerator; A first water supply branch pipe (P1) is provided from the outlet condensate pipe of the secondary low-pressure heater of the steam-water system of the steam turbine to the first desalted water tank (1); a second water supply branch pipe (P2) is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank (1); a third water supply branch pipe (P3) is provided from the outlet condensate pipe of the secondary low-pressure heater to the first desalted water tank (1); a fourth water supply branch pipe (P4) is provided from the outlet condensate pipe of the final low-pressure heater to the first desalted water tank (1); A water outlet pipe (P6) is provided from the second desalted water tank (2) to the condenser hot well; a water supply pipe (P7) is provided from the condensate pump outlet to the second desalted water tank (2); A hole is drilled and a tee is added on the condensate water pipe at the outlet of the final low-pressure heater to connect to the fourth water supply branch pipe (P4), and a first water supply branch pipe valve group (V1) is installed on the fourth water supply branch pipe (P4); a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-final low-pressure heater to connect to the first water supply branch pipe (P1), and a second water supply branch pipe valve group (V2) is installed on the first water supply branch pipe (P1); a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-second-final low-pressure heater to connect to the second water supply branch pipe (P2), and a third water supply branch pipe valve group (V3) is installed on the second water supply branch pipe (P2); a hole is drilled and a tee is added on the condensate water pipe at the outlet of the second-second-final low-pressure heater to connect to the third water supply branch pipe (P3), and a fourth water supply branch pipe valve group (V4) is installed on the third water supply branch pipe (P3); The first desalted water tank (1) and the second desalted water tank (2) are provided with an external insulation layer, which can ensure that the water temperature of the desalted water tank does not drop by more than 4°C when the tank is full and the water is left standing for 4 hours; The operating method includes a heat storage peak regulation operating mode and an energy release operating mode; A. Thermal storage peak load regulation operation modes include: The second desalted water tank (2) is filled with cold water, and the first desalted water tank (1) is empty; According to the outlet water temperature of each level of low-pressure heater, use the opening of the valve group to control the water temperature of the water supply main pipe (P5) to not exceed 97℃; According to the peak load depth and peak load duration, the flow rate adjustment range of the water supply main pipe (P5) is 0 t / h~F cp_out， Among them, F cp_out is the condensate flow rate under the original maximum deep adjustment load of the steam turbine; During heat storage, cold water from the second desalted water tank (2) is continuously injected into the condenser hot well via the cold water delivery pump (4), and the water level in the second desalted water tank (2) is continuously reduced until the liquid level reaches zero; hot water flows into the first desalted water tank (1) via the water supply main pipe (P5), and the water level in the water tank is continuously increased until the liquid level reaches the upper limit, and the water temperature is maintained at 97°C; When the load demand of the power grid is low and the unit needs to be in a deep peak-shaving operation condition, a large amount of 97°C condensate is stored from the condensate pipe to the first desalted water tank (1), which increases the steam extraction of the low-pressure cylinder of the steam turbine, thereby reducing the load of the unit; cold water from the second desalted water tank (2) is continuously injected into the condenser, increasing the condensate flow through the low-pressure heater; B. The energy release reset operation mode and functions are as follows: Before the energy is initially released, the second desalted water tank (2) is empty and the first desalted water tank (1) is filled with hot water; The hot water in the first desalted water tank (1) enters the deaerator inlet condensate pipe through the condensate pipe (P8); The condensate at the outlet of the condensate pump enters the second desalted water tank (2) through the water supply pipe (P7); When the grid load does not require the unit to perform deep peak regulation and the unit output meets the grid requirements, the unit selects an opportunity to release energy, and the unit operates in this energy release reset operation mode; the hot water in the first desalted water tank (1) continuously enters the condensate water system until the liquid level reaches zero, and the second desalted water tank (2) continuously injects cold water until the liquid level reaches the upper limit; When the unit's power output is insufficient in the summer, the unit also operates in the energy release and reset operation mode, increasing the unit's output by controlling the valve group opening and transmission output.

2. The method for operating a heat storage peak-shaving system based on a desalted water tank according to claim 1, characterized in that: The first water supply branch pipe (P1), the second water supply branch pipe (P2), the third water supply branch pipe (P3) and the fourth water supply branch pipe (P4) are merged into a water supply main pipe (P5), and a water supply main pipe valve group (V9) is installed on the water supply main pipe (P5).

3. The method for operating a heat storage peak-shaving system based on a desalted water tank according to claim 1, characterized in that: The water outlet pipe (P6) is provided with a water outlet pipe valve group (V6); the water supply pipe (P7) is provided with a water supply pipe valve group (V7); and the condensate water pipe (P8) is provided with a condensate water pipe valve group (V5).

4. The method for operating a heat storage peak-shaving system based on a desalted water tank according to claim 3, characterized in that: A valve group (V8) is installed on the downstream condensate pipeline from the outlet of the condensate pump of the steam-water system of the steam turbine unit to the water supply three-way point of the water supply pipeline (P7).

5. The method for operating a heat storage peak-shaving system based on a desalted water tank according to claim 3, characterized in that: The condensate pipeline (P8) is equipped with a condensate pipeline valve group (V5) and a hot water delivery pump (3); the outlet pipeline (P6) is equipped with an outlet pipeline valve group (V6) and a cold water delivery pump (4).

6. The method for operating a heat storage peak-shaving system based on a desalted water tank according to claim 1, characterized in that: The steam-water system of the steam turbine unit further comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder; the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder coaxially drive a generator to generate electricity.

7. The method for operating a thermal storage peak-shaving system based on a desalted water tank according to claim 1, characterized in that: The opening method of the valve group in the thermal storage peak regulation operation mode is: a) When T P4 When the temperature is less than 97℃, only the first water supply branch pipe valve group (V1) is opened; the second water supply branch pipe valve group (V2), the third water supply branch pipe valve group (V3), and the fourth water supply branch pipe valve group (V4) are closed; b) When T P4 ≥97℃, and T P1 <97°C, open the first water supply branch pipe valve group (V1) and the second water supply branch pipe valve group (V2), and close the third water supply branch pipe valve group (V3) and the fourth water supply branch pipe valve group (V4); c) When T P1 ≥97℃, and T P2 <97°C, open the second water supply branch pipe valve group (V2) and the third water supply branch pipe valve group (V3), and close the first water supply branch pipe valve group (V1) and the fourth water supply branch pipe valve group (V4); d) When T P2 ≥97℃, and T P3 <97°C, open the third water supply branch pipe valve group (V3) and the fourth water supply branch pipe valve group (V4), and close the first water supply branch pipe valve group (V1) and the fourth water supply branch pipe valve group (V4).

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