Thermal power unit heat storage peak regulation device and method, thermal power unit and power generation system

Abstract

The present invention discloses a heat storage peak-shaving device and method for a thermal power unit, a thermal power unit and a power generation system. The peak-shaving device includes: a heat exchanger, whose high-temperature side is connected to the reheat steam pipeline of the thermal power unit; a high-temperature heat exchange medium storage tank; a steam generator, whose heat exchange medium inlet is connected to the outlet of the high-temperature heat exchange medium storage tank; a low-temperature heat exchange medium storage tank, whose inlet is connected to the heat exchange medium outlet of the steam generator, and the outlet of the low-temperature heat exchange medium storage tank is connected to the low-temperature side inlet of the heat exchanger; and a peak-shaving steam turbine connected to the steam outlet of the steam generator. The heat storage peak-shaving device of the thermal power unit of the present invention extracts a certain amount of high-temperature reheat steam during the off-peak period of electricity consumption, and exchanges heat with the low-temperature heat exchange medium to form a high-temperature heat exchange medium, which is stored in the high-temperature heat exchange medium storage tank; during the peak period of electricity consumption, the high-temperature heat exchange medium is sent to the steam generator, and the generated steam drives the peak-shaving steam turbine to generate electricity to achieve high-efficiency cascade utilization of heat.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation, and in particular relates to a heat storage peak-shaving device and method for a thermal power unit, a thermal power unit and a power generation system. Background Art

[0002] At present, the installed capacity of coal-fired power in China is about 1.1 billion kilowatts, which is the supporting and basic power source of my country's power system. With the increase in the proportion of new energy and the increase in the peak-to-valley difference in electricity consumption, the peak-shaving pressure of the power system has increased year by year, and thermal power units have gradually shifted from base load operation to peak-shaving operation. The increase in the peak-shaving pressure of the power system has caused two problems. First, during the period of large-scale new energy production and low electricity consumption, a large number of "wind abandonment", "water abandonment" and even "light abandonment" problems have occurred, resulting in a waste of resources; second, during the period of insufficient new energy production and peak electricity consumption, there has been a shortage of power supply, resulting in "power rationing" problems, affecting the normal operation of the economy and society. With the adjustment of the industrial structure, the peak-to-valley difference in electricity consumption will continue to increase, and with the substantial increase in the scale of new energy, the peak-shaving pressure of the power system will continue to increase, and the system's peak-shaving capacity has become an increasingly scarce capacity.

[0003] For thermal power units, they are in low-load operation during low-power consumption or when new energy is in high demand, and there is still a large amount of idle generating capacity; while during peak power consumption or when new energy is under-developed, the power system hopes that thermal power units will have greater generating capacity to avoid power restrictions. The deep peak-shaving capacity and overload capacity of the existing thermal power units are very limited. After the transformation, the increase in the upward adjustment capacity does not exceed 5% of the original capacity, and the increase in the downward adjustment capacity generally does not exceed 10%. The implementation effect is not obvious. Operation beyond the established peak-shaving range will cause the efficiency of the generator set to decrease and the coal consumption to increase. Summary of the invention

[0004] (I) Purpose of the invention

[0005] The object of the present invention is to provide a thermal storage peak-shaving device and method for a thermal power unit, a thermal power unit and a power generation system to solve the above-mentioned problems.

[0006] (II) Technical solution

[0007] To solve the above problems, the first aspect of the present invention provides a heat storage and peak-shaving device for a thermal power unit, comprising: a heat exchanger, whose high-temperature side is connected to the reheat steam pipeline of the thermal power unit; a high-temperature heat exchange medium storage tank, whose inlet is connected to the low-temperature side outlet of the heat exchanger; a steam generator, whose heat exchange medium inlet is connected to the outlet of the high-temperature heat exchange medium storage tank; a low-temperature heat exchange medium storage tank, the inlet of the low-temperature heat exchange medium storage tank is connected to the heat exchange medium outlet of the steam generator, and the outlet of the low-temperature heat exchange medium storage tank is connected to the low-temperature side inlet of the heat exchanger; and a peak-shaving steam turbine, which is connected to the steam outlet of the steam generator.

[0008] Furthermore, it also includes: a circulation pump; the circulation pump is arranged between the high-temperature heat exchange medium storage tank and the steam generator; and / or the circulation pump is arranged between the low-temperature heat exchange medium storage tank and the heat exchanger.

[0009] Furthermore, the heat exchange medium is one or more of binary molten salt, volcanic rock, magnesia brick, silicone oil and concrete.

[0010] According to another aspect of the present invention, a heat storage peak-shaving method for a thermal power unit is provided, comprising: during a period of low electricity consumption, part of the steam generated by the thermal power unit heats a low-temperature heat exchange medium through a heat exchanger to form a high-temperature heat exchange medium; the high-temperature heat exchange medium is stored in a high-temperature storage tank; during a period of peak electricity consumption, the high-temperature heat exchange medium is transported to a steam generator to obtain steam, and the steam is transported to a peak-shaving steam turbine to generate electricity; the high-temperature heat exchange medium forms a low-temperature heat exchange medium after passing through the steam generator, and the low-temperature heat exchange medium is stored in a low-temperature storage tank.

[0011] Furthermore, it also includes: the high-temperature heat exchange medium in the high-temperature heat exchange medium storage tank enters the steam generator through a circulation pump; the low-temperature heat exchange medium in the low-temperature heat exchange medium storage tank passes through the heat exchanger through a circulation pump and becomes the high-temperature heat exchange medium.

[0012] According to another aspect of the present invention, there is provided a thermal power unit, comprising the heat storage peak-shaving device of the thermal power unit according to any one of the above-mentioned solutions.

[0013] Furthermore, it also includes: a boiler; a main steam turbine high-pressure cylinder, whose inlet is connected to the high-temperature steam outlet of the boiler; and whose outlet is connected to the high-temperature side inlet of the heat exchanger in the peak-shaving device; a steam mixer, whose inlet is connected to the outlet of the main steam turbine high-pressure cylinder and the high-temperature side outlet of the heat exchanger in the peak-shaving device respectively; a main steam turbine intermediate-pressure cylinder, whose inlet is connected to the outlet of the steam mixer, and a main steam turbine low-pressure cylinder, whose inlet is connected to the outlet of the main steam turbine intermediate-pressure cylinder.

[0014] Furthermore, it also includes: a deaerator, the inlet of which is respectively connected to the outlet of the low-pressure cylinder of the main steam turbine, the outlet of the intermediate-pressure cylinder of the main steam turbine and the high-temperature side outlet of the heat exchanger.

[0015] Furthermore, it also includes: a plurality of valves; the valve is arranged between the outlet of the high-pressure cylinder of the main steam turbine and the outlet of the high-temperature side of the heat exchanger; the valve is arranged between the inlet of the steam mixer and the outlet of the high-temperature side of the heat exchanger; the valve is arranged between the outlet of the high-temperature side of the heat exchanger and the inlet of the deaerator.

[0016] Furthermore, it also includes: a reheater, whose inlet is connected to the boiler; and whose outlet is connected to the inlet of the high-pressure cylinder of the main steam turbine.

[0017] Furthermore, it also includes: a boiler; a main steam turbine high-pressure cylinder, whose inlet is connected to the high-temperature steam outlet of the boiler; whose outlet is connected to the high-temperature side inlet of the heat exchanger in the peak-shaving device; a main steam turbine intermediate-pressure cylinder, whose inlet is connected to the high-temperature side outlet of the heat exchanger; and a main steam turbine low-pressure cylinder, whose inlet is connected to the outlet of the main steam turbine intermediate-pressure cylinder.

[0018] Furthermore, it also includes: a deaerator, the inlet of which is connected to the outlet of the low-pressure cylinder of the main steam turbine and the outlet of the intermediate-pressure cylinder of the main steam turbine respectively.

[0019] Furthermore, it also includes: a reheater, whose inlet is connected to the boiler; and whose outlet is connected to the high-temperature side outlet of the heat exchanger in the peak-shaving device.

[0020] Furthermore, it also includes: a condenser, whose inlet is connected to the outlet of the low-pressure cylinder of the main steam turbine; a low-pressure heater, whose inlet is connected to the outlet of the condenser; and whose outlet is connected to the deaerator.

[0021] Furthermore, it also includes: a valve; which is arranged between the intermediate pressure cylinder of the main steam turbine and the inlet of the deaerator.

[0022] According to another aspect of the present invention, there is provided a power generation system, comprising the heat storage peak-shaving device of the thermal power unit described in any one of the above schemes or the thermal power unit described in any one of the above schemes.

[0023] (III) Beneficial effects

[0024] The above technical solution of the present invention has the following beneficial technical effects:

[0025] The heat storage peak-shaving device of the thermal power unit of the present invention extracts a certain amount of reheated steam during the off-peak period of electricity consumption, and exchanges heat with the low-temperature heat exchange medium to form a high-temperature heat exchange medium, which is stored in the high-temperature heat exchange medium storage tank; during the peak period of electricity consumption, the high-temperature heat exchange medium is sent to the steam generator, and the generated steam drives the peak-shaving steam turbine to generate electricity. At the same time, the steam after heat exchange with the molten salt is heat recovered. According to the temperature of the steam after heat exchange, it can be sent to the deaerator for steam-water mixing, while reducing the steam extraction from the medium-pressure cylinder to the deaerator; or sent to the high-pressure heater for steam-water heat exchange, while reducing the steam extraction from the high-pressure cylinder to the high-pressure heater; or sent to the steam mixer and enter the steam turbine intermediate-pressure cylinder, so as to achieve high-efficiency cascade utilization of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a peak shaving device according to an embodiment of the present invention.

[0027] Figure 2 is a schematic diagram of a peak shaving device according to yet another embodiment of the present invention.

[0028] Reference numerals:

[0029] 1: Peak-shaving steam turbine; 2: Low-temperature heat exchange medium storage tank; 3: High-temperature heat exchange medium storage tank; 4: Steam generator; 5: Heat exchanger; 6: Circulating pump; 7: Main steam turbine high-pressure cylinder; 8: Main steam turbine medium-pressure cylinder; 9: Main steam turbine low-pressure cylinder; 10: Steam mixer; 11: Condenser; 12: Low-pressure heater; 13: Deaerator; 14: High-pressure heater; 15: Valve; 16: Reheater; 17: Boiler; 18: Main generator; 19: Peak-shaving generator.

[0030] The dotted lines in the figure represent the rotors of the generators (main generators and peak-shaving generators) in the thermal power units. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0032] The accompanying drawings show schematic diagrams of layer structures according to embodiments of the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clarity. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0033] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0036] Figure 1is a schematic diagram of a peak shaving device according to an embodiment of the present invention.

[0037] Figure 2 is a schematic diagram of a peak shaving device according to yet another embodiment of the present invention.

[0038] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, a heat storage peak-shaving device of a thermal power unit is provided, which may include: a heat exchanger 5, whose high temperature side is connected to the reheat steam pipeline of the thermal power unit; a high temperature heat exchange medium storage tank 3, whose inlet is connected to the low temperature side outlet of the heat exchanger 5; a steam generator 4, whose heat exchange medium inlet is connected to the outlet of the high temperature heat exchange medium storage tank 3; a low temperature heat exchange medium storage tank 2, whose inlet is connected to the heat exchange medium outlet of the steam generator 4, and whose outlet is connected to the low temperature side inlet of the heat exchanger 5; and a peak-shaving steam turbine 1, wherein the peak-shaving steam turbine 1 is connected to the steam outlet of the steam generator 4. The heat storage peak-shaving device of the thermal power unit of the present invention extracts a certain amount of reheat steam during the off-peak period of electricity consumption, and exchanges heat with the low temperature heat exchange medium to form a high temperature heat exchange medium, which is stored in the high temperature heat exchange medium storage tank 3; during the peak period of electricity consumption, the high temperature heat exchange medium is sent to the steam generator 4, and the generated steam drives the small peak-shaving steam turbine 1 to generate electricity. The temperature of reheated steam is close to that of main steam, but the pressure is much lower (generally 3MPa) and much lower than that of main steam (generally more than 15MPa). The heat exchange between medium-pressure high-temperature steam and heat exchange medium is easier to achieve technically, avoiding unnecessary throttling losses and lowering the cost. At the same time, after the reheated steam is heat exchanged with molten salt, it will be sent to the deaerator 13 for steam-water mixing, while reducing the steam extraction from the medium-pressure cylinder to the deaerator 13, realizing high-efficiency step-by-step utilization of heat.

[0039] In an optional embodiment, the heat storage and peak-shaving device of the thermal power unit may also include: a circulating pump 6; the circulating pump 6 is arranged between the high-temperature heat exchange medium storage tank 3 and the steam generator 4; and / or the circulating pump 6 is arranged between the low-temperature heat exchange medium storage tank 2 and the heat exchanger 5.

[0040] In an optional embodiment, the heat exchange medium is one or more of binary molten salt, volcanic rock, magnesia brick, silicone oil and concrete.

[0041] In another embodiment of the present invention, a heat storage peak-shaving method for a thermal power unit is provided, which may include: during a period of low electricity consumption, part of the steam generated by the thermal power unit heats a low-temperature heat exchange medium through a heat exchanger 5 to form a high-temperature heat exchange medium; the high-temperature heat exchange medium is stored in a high-temperature storage tank 3; during a period of peak electricity consumption, the high-temperature heat exchange medium is transported to a steam generator 4 to obtain steam, and the steam is transported to a peak-shaving steam turbine 1 to generate electricity; the high-temperature heat exchange medium forms a low-temperature heat exchange medium after passing through the steam generator 4, and the low-temperature heat exchange medium is stored in a low-temperature storage tank 2.

[0042] In an optional embodiment, the heat storage peak-shaving method of the thermal power unit may also include: the high-temperature heat exchange medium in the high-temperature heat exchange medium storage tank 3 enters the steam generator 4 through the circulating pump 6; the low-temperature heat exchange medium in the low-temperature heat exchange medium storage tank 2 passes through the heat exchanger 5 through the circulating pump 6 to become the high-temperature heat exchange medium.

[0043] In another embodiment of the present invention, a thermal power unit is provided, which may include the heat storage peak-shaving device of the thermal power unit described in any one of the above-mentioned solutions.

[0044] In an optional embodiment, the thermal power unit may also include: a boiler 17; a main steam turbine high-pressure cylinder 7, whose inlet is connected to the high-temperature steam outlet of the boiler 17; and whose outlet is connected to the high-temperature side inlet of the heat exchanger 5 in the peak-shaving device; a steam mixer 10, whose inlet is respectively connected to the outlet of the main steam turbine high-pressure cylinder 7 and the high-temperature side outlet of the heat exchanger 5 in the peak-shaving device; a main steam turbine intermediate-pressure cylinder 8, whose inlet is connected to the outlet of the steam mixer 10, and a main steam turbine low-pressure cylinder 9, whose inlet is connected to the outlet of the main steam turbine intermediate-pressure cylinder 8.

[0045] In an optional embodiment, the thermal power unit may further include: a deaerator 13, whose inlet is connected to the outlet of the main steam turbine low-pressure cylinder 9, the outlet of the main steam turbine intermediate-pressure cylinder 8 and the high-temperature side outlet of the heat exchanger 5 respectively.

[0046] In an optional embodiment, the thermal power unit may further include: a valve 15; the valve 15 is arranged between the outlet of the high-pressure cylinder 7 of the main steam turbine and the high-temperature side outlet of the heat exchanger 5;

[0047] In an optional embodiment, the thermal power unit may further include: a valve 15; the valve 15 is arranged between the inlet of the steam mixer 10 and the high temperature side outlet of the heat exchanger 5;

[0048] In an optional embodiment, the thermal power unit may further include: a valve 15 ; the valve 15 is arranged between the high temperature side outlet of the heat exchanger 5 and the inlet of the deaerator 13 .

[0049] In an optional embodiment, the thermal power unit may further include: a reheater 16 , an inlet of which is connected to the boiler 17 ; and an outlet of which is connected to the inlet of the high-pressure cylinder 7 of the main steam turbine.

[0050] In an optional embodiment, the thermal power unit may further include: a high-pressure heater 14 , whose high-temperature side inlet is connected to the high-temperature side outlet of the heat exchanger 5 , and whose low-temperature side inlet is connected to the outlet of the deaerator 13 .

[0051] In an optional embodiment, the thermal power unit may further include: a pump, which is arranged between the outlet of the deaerator 13 and the high-pressure heater 14 .

[0052] In an optional embodiment, the thermal power unit may further include: a valve 15 ; the valve 15 is arranged between the high temperature side outlet of the heat exchanger 5 and the high temperature side inlet of the high pressure heater 14 .

[0053] In an optional embodiment, the thermal power unit may further include: a pump, which is arranged between the outlet of the deaerator 13 and the high-pressure heater 14 .

[0054] In an optional embodiment, the thermal power unit may also include: a boiler 17; a main steam turbine high-pressure cylinder 7, whose inlet is connected to the high-temperature steam outlet of the boiler 17; whose outlet is connected to the high-temperature side inlet of the heat exchanger 5 in the peak-shaving device; a main steam turbine intermediate-pressure cylinder 8, whose inlet is connected to the high-temperature side outlet of the heat exchanger 5; and a main steam turbine low-pressure cylinder 9, whose inlet is connected to the outlet of the main steam turbine intermediate-pressure cylinder 8.

[0055] In an optional embodiment, the thermal power unit may further include: a deaerator 13, the inlet of which is connected to the outlet of the main steam turbine low-pressure cylinder 9 and the outlet of the main steam turbine intermediate-pressure cylinder 8 respectively.

[0056] In an optional embodiment, the thermal power unit may further include: a reheater 16, whose inlet is connected to the boiler 17; and whose outlet is connected to the high-temperature side outlet of the heat exchanger 5 in the peak-shaving device.

[0057] In an optional embodiment, the thermal power unit may further include: a valve 15 ; which is arranged between the outlet of the reheater 16 and the high temperature side inlet of the heat exchanger 5 .

[0058] In an optional embodiment, the thermal power unit may further include: a valve 15 ; which is arranged between the high temperature side outlet of the heat exchanger 5 and the inlet of the intermediate pressure cylinder 8 of the main steam turbine.

[0059] In an optional embodiment, the thermal power unit may further include: a high-pressure heater 14 , a low-temperature side inlet of which is connected to the outlet of the deaerator 13 .

[0060] In an optional embodiment, the thermal power unit may further include: a pump, which is arranged between the outlet of the deaerator 13 and the high-pressure heater 14 .

[0061] In an optional embodiment, the thermal power unit may further include: a condenser 11, whose inlet is connected to the outlet of the main steam turbine low-pressure cylinder 9; a low-pressure heater, whose inlet is connected to the outlet of the condenser 11; and whose outlet is connected to the deaerator 13.

[0062] In an optional embodiment, the thermal power unit may further include: a valve 15 ; which is arranged between the intermediate pressure cylinder 8 of the main steam turbine and the inlet of the deaerator 13 .

[0063] In an optional embodiment, the thermal power unit may further include: a main generator 18, the rotor of the main generator 18 passes through the main steam turbine high-pressure cylinder 7, the main steam turbine intermediate-pressure cylinder 8 and the main steam turbine low-pressure cylinder 9, and the three cylinders of the main steam turbine drive the rotor to rotate to generate electricity.

[0064] In an optional embodiment, the thermal power unit may further include: a peak-shaving generator 19, wherein the rotor of the peak-shaving generator 19 passes through the peak-shaving steam turbine 1, and the rotor is driven by the peak-shaving steam turbine 1 to rotate to generate electricity.

[0065] In another embodiment of the present invention, a power generation system is provided, comprising the heat storage peak-shaving device of the thermal power unit described in any one of the above schemes or the thermal power unit described in any one of the above schemes.

[0066] The peak-shaving steam turbine 1 is a rotary steam power device that converts steam into mechanical energy, which in turn drives a generator to generate electrical energy. The peak-shaving steam turbine 1 of the present invention generates electricity during peak load periods and is in a standby state during off-peak periods.

[0067] Low temperature heat exchange medium storage tank 2: used to store low temperature liquid molten salt. Molten salt is generally nitrate, and the storage temperature is about 280℃.

[0068] High temperature heat exchange medium storage tank 3: used to store high temperature liquid molten salt. Molten salt is generally nitrate, and the storage temperature is about 570℃.

[0069] Steam generator 4: used to transfer the heat stored in the hot molten salt to water and form steam, driving the peak-shaving steam turbine 1 to generate electricity. The steam generator 4 is a three-stage design, including a preheater, an evaporator and a superheater.

[0070] Heat exchanger 5: used to transfer the heat of the reheated steam to the cold molten salt, and the cold molten salt is heated to form hot molten salt.

[0071] Circulation pump 6: used to adjust the flow rate of the molten salt as needed, and control the heat absorption and temperature of the molten salt.

[0072] Main steam turbine high pressure cylinder 7: A part of the steam turbine of an existing coal-fired power plant, which converts high-temperature and high-pressure main steam into mechanical energy and discharges medium-temperature and medium-pressure steam.

[0073] Main steam turbine intermediate pressure cylinder 8: A part of the steam turbine of an existing coal-fired power plant, which converts high-temperature and low-pressure reheated steam into mechanical energy and discharges low-temperature and low-pressure steam.

[0074] Main steam turbine low pressure cylinder 9: A part of the steam turbine of an existing coal-fired power plant that converts low temperature and low pressure steam into mechanical energy.

[0075] Steam mixer 10: A component that evenly mixes steam of different temperatures and pressures. Its input is reheated steam and steam after heat exchange with molten salt, and the output steam is sent to the intermediate pressure cylinder of the steam turbine.

[0076] Condenser 11: A heat exchanger 5 that condenses turbine exhaust steam into water.

[0077] Deaerator 13: Removes dissolved oxygen and other gases in the feed water of the thermal system to prevent corrosion of thermal equipment. Its input is condensed water and high-temperature steam and outputs feed water.

[0078] Valve 15: A mechanical device for controlling steam flow, with functions such as diversion, cut-off, check and pressure-stabilizing steam.

[0079] Coal-fired boiler 17 reheater 16: located in the flue of the coal-fired boiler 17, it uses high-temperature flue gas to heat the steam discharged from the high-pressure cylinder 7 of the main steam turbine, raising the steam temperature by 100-150°C.

[0080] Boiler 17: The coal-fired boiler 17 of the existing coal-fired power station converts the chemical energy of coal into thermal energy.

[0081] Molten salt (heat exchange medium) heating and steam waste heat recovery

[0082] Process 1: Molten salt heating. If the molten salt is heated by partial reheat steam, the valve 15 of the reheat steam bypass channel is opened during the off-peak period of electricity consumption to extract a certain amount of reheat steam and send it to the heat exchanger 5; if the molten salt is heated by all reheat steam, all reheat steam passes through the heat exchanger 55. At the same time, the circulating pump 6 is started to send the cold molten salt in the low-temperature heat exchange medium storage tank 2 to the heat exchanger 55, the molten salt is heated by steam, and sent to the high-temperature molten salt tank for storage.

[0083] Process 2: Steam mixing. If a partial reheat steam heating molten salt solution is adopted, a portion of the reheat steam after heat exchange with the molten salt is sent to the steam mixer 10 to mix with the remaining reheat steam, and then sent to the main steam turbine intermediate pressure cylinder 8. If a full reheat steam heating molten salt solution is adopted, the reheat steam after heat exchange directly enters the main steam turbine intermediate pressure cylinder 8.

[0084] Process 3: Steam-water mixing. If a partial reheat steam heating molten salt solution is adopted, part of the reheat steam after heat exchange with the molten salt is sent to the deaerator 13 to heat the feed water, and the steam extraction from the intermediate pressure cylinder 9 of the main steam turbine to the deaerator 13 is appropriately reduced. If a full reheat steam heating molten salt solution is adopted, this process does not exist.

[0085] Process 4: Steam-water heat exchange. If a partial reheat steam heating molten salt solution is adopted, part of the reheat steam after heat exchange with the molten salt is sent to the high-pressure heater 14 to heat the feed water, and the steam extraction from the main steam turbine intermediate pressure cylinder 8 or the main steam turbine intermediate pressure cylinder 9 to the high-pressure heater 14 is appropriately reduced. If a full reheat steam heating molten salt solution is adopted, this process does not exist.

[0086] Peaking steam turbine power generation

[0087] During the peak period of electricity consumption, the circulating pump 6 delivers high-temperature molten salt to the steam generator 4, and generates high-temperature and high-pressure steam through the preheater, evaporator and superheater in the steam generator 4. The high-temperature and high-pressure steam enters the peak-shaving steam turbine 1 to drive the steam turbine to generate electricity and meet the electricity demand of the system.

[0088] The present invention proposes a method of heating molten salt by using reheated steam. The present invention proposes to heat molten salt by using reheated steam. This mode solves the problems existing in the existing technology of using high-pressure main steam and molten salt for heat exchange. The technology used is more mature, and the technical solution is more concise, efficient and economical.

[0089] The steam mixing method proposed in the present invention. The temperature of the reheated steam after heat exchange with molten salt drops to about 300°C. Direct discharge will cause energy loss and waste. Therefore, the present invention proposes to use a steam mixer 10 to mix the reheated steam after heat exchange with the remaining reheated steam, and use the temperature deviation space of the reheated steam to recover steam energy.

[0090] The steam-water mixing method proposed by the present invention. The present invention observed that the temperature of the reheated steam after heat exchange is basically equivalent to the steam extraction of the intermediate pressure cylinder. Considering that the allowable deviation space of the reheated steam temperature is small, in order to achieve a larger scale of reheated steam extraction, the present invention proposes to send the reheated steam after heat exchange into the deaeration water tank to replace the original steam extraction of the intermediate pressure cylinder.

[0091] Effects of the present invention:

[0092] (1): Significantly improve the peak load regulation capability of coal-fired power units. By adding a peak load regulation steam turbine, the peak load regulation capability of coal-fired power units can be increased by about 20% to 30% without affecting the safety and stability of the operation of the coal-fired boiler 17 and steam turbine of the existing units.

[0093] (2): High overall efficiency. Reheated steam is used to heat the molten salt. Compared with the efficiency of the medium and low pressure cylinders, the efficiency of the small steam turbine reaches 80% of the efficiency of the medium and low pressure cylinders. At the same time, the present invention proposes to send the steam after heat exchange to the deaerator, high pressure heater or steam mixer according to its temperature, thereby avoiding energy waste caused by direct discharge. Moreover, the pressure of the reheated steam is much lower than that of the main steam, thereby avoiding unnecessary throttling losses. Therefore, the efficiency of the present invention is higher than that of the technical route of using main steam for molten salt heating.

[0094] (3): High energy density, suitable for large-scale promotion. Considering the construction of a 50MW peak-shaving steam turbine 1 for 2×300MW coal-fired power units, the molten salt heat storage hours are considered to be 4 hours (heat storage capacity 500MWh). The project requires an area of ​​only 5,000 square meters, which is only 1 / 8 of the same scale of electric energy storage, and is more suitable for large-scale promotion.

[0095] (4): Low overall cost. The cost of molten salt heat storage is only 50 yuan / kWh, which is much lower than electrochemical energy storage. At the same time, the direct heating method proposed in the present invention reduces the steam heat exchange device, further reducing the cost. The unit kilowatt cost can be reduced to less than 4,000 yuan / kW, which is lower than pumped storage power stations and electrochemical energy storage.

[0096] Consider using this patented technology to transform a coal-fired power plant. The power plant currently has 2×350MW supercritical generating units with a peak-shaving capacity of 40-100%, that is, the power generation range of a single unit is 140MW-350MW. Two of the 350MW units are transformed for peak-shaving.

[0097] (I) Construction plan

[0098] 1. Build a new 50MW small steam turbine with main steam parameters of 14MPa and 550℃.

[0099] 2. New cold and hot molten salt storage tanks are built. The heat storage medium is binary molten salt, the temperature of cold molten salt is 290°C, the temperature of hot molten salt is 565°C, and the heat storage capacity is 500MWhth.

[0100] 3. The steam flow rate of the newly built steam generator is 127.7t / h, and the steam parameters of the reheater 16 are 2.62MPa, 553℃. The feed water temperature is 250.8℃.

[0101] 4. Build 552 sets of new heat exchangers with a heat exchange capacity of 15MW, totaling 30MW.

[0102] 5. Build a new reheat steam extraction pipeline, a new heat exchanger to deaerator pipeline, and a new heat exchanger to high-pressure heater pipeline.

[0103] (II) Reheat steam extraction scheme

[0104] Under full load conditions (BMCR), the reheat steam flow rate is 900 tons / hour; the reheat steam parameters are 4.2MPa, 570℃.

[0105] Considering the extraction of steam at 50% BMCR, the reheat steam flow rate is about 450 tons / hour; the reheat steam parameters are 2.5MPa, 565℃. Under the premise of ensuring axial thrust balance, the reheat steam is extracted at 100 tons / hour, the reheat steam temperature after heat exchange is 320℃, and the molten salt absorption power is 15MW. After heat exchange, part of the reheat steam (60 tons / hour) is sent to the deaerator 13, and the extraction of steam from the intermediate pressure cylinder to the deaerator 13 is reduced accordingly; part (40 tons / hour) is sent to the high-pressure heater 14.

[0106] (III) Operation mode

[0107] The molten salt heat storage period is 15-20 hours, the heat storage power is between 10 and 15MW, the heat storage power is related to the boiler load, and the daily heat storage is about 500MWhth. During the peak power consumption period (usually the evening peak), the small steam turbine is started to generate electricity, and the power generation time is 4 hours.

[0108] The present invention aims to protect a heat storage peak-shaving device and method for a thermal power unit, a thermal power unit and a power generation system, wherein the peak-shaving device comprises: a heat exchanger 5, whose high-temperature side is connected to the reheat steam pipeline of the thermal power unit; a high-temperature heat exchange medium storage tank 3, whose inlet is connected to the low-temperature side outlet of the heat exchanger 5; a steam generator 4, whose inlet is connected to the outlet of the high-temperature heat exchange medium storage tank 3; a low-temperature heat exchange medium storage tank 2, whose inlet is connected to the outlet of the steam generator 4, and whose outlet is connected to the low-temperature side inlet of the heat exchanger 5; and a peak-shaving steam turbine 1, wherein the peak-shaving steam turbine 1 is connected to the steam outlet of the steam generator 4. The heat storage peak-shaving device for the thermal power unit of the present invention extracts a certain amount of reheat steam during the off-peak period of electricity consumption, and exchanges heat with the low-temperature heat exchange medium to form a high-temperature heat exchange medium, which is stored in the high-temperature heat exchange medium storage tank 3; during the peak period of electricity consumption, the high-temperature heat exchange medium is sent to the steam generator 4, and the steam generated drives the peak-shaving steam turbine 1 to generate electricity. The temperature of reheated steam is close to that of main steam, but the pressure is much lower (generally 3MPa) and much lower than that of main steam (generally more than 15MPa). The heat exchange between medium-pressure high-temperature steam and heat exchange medium is easier to achieve technically and the cost is lower. At the same time, after the reheated steam is heat exchanged with molten salt, part of it will be sent to the deaerator 13 for steam-water mixing, while reducing the steam extraction from the medium-pressure cylinder 8 to the deaerator 13; part of it will be sent to the high-pressure heater 14 for steam-water heat exchange, while reducing the steam extraction from the medium-pressure cylinder 8 to the high-pressure heater 14, realizing high-efficiency step-by-step utilization of heat.

[0109] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A thermal power unit, characterized in that: It comprises a heat storage peak regulation device for a thermal power unit; and also comprises: Boiler (17); A main steam turbine high-pressure cylinder (7), whose inlet is connected to the high-temperature steam outlet of the boiler (17); and whose outlet is connected to the high-temperature side inlet of the heat exchanger (5) in the heat storage peak-shaving device; A steam mixer (10), the inlet of which is respectively connected to the outlet of the high-pressure cylinder (7) of the main steam turbine and the high-temperature side outlet of the heat exchanger (5) in the peak-shaving device; The inlet of the intermediate pressure cylinder (8) of the main steam turbine is connected to the outlet of the steam mixer (10). A main steam turbine low-pressure cylinder (9), the inlet of which is connected to the outlet of the main steam turbine intermediate-pressure cylinder (8); a deaerator (13), the inlet of which is respectively connected to the outlet of the main steam turbine low-pressure cylinder (9), the outlet of the main steam turbine intermediate-pressure cylinder (8) and the high-temperature side outlet of the heat exchanger (5); A high-pressure heater (14), wherein a high-temperature side inlet thereof is connected to a high-temperature side outlet of the heat exchanger (5), and a low-temperature side inlet thereof is connected to an outlet of the deaerator (13); The heat storage peak-shaving device of the thermal power unit comprises: A heat exchanger (5), the high temperature side of which is connected to a reheat steam pipeline of a thermal power unit; A high-temperature heat exchange medium storage tank (3), the inlet of which is connected to the low-temperature side outlet of the heat exchanger (5); A steam generator (4), the heat exchange medium inlet of which is connected to the outlet of the high-temperature heat exchange medium storage tank (3); A low-temperature heat exchange medium storage tank (2), wherein the inlet of the low-temperature heat exchange medium storage tank (2) is connected to the heat exchange medium outlet of the steam generator (4), and the outlet of the low-temperature heat exchange medium storage tank (2) is connected to the low-temperature side inlet of the heat exchanger (5); A peak-shaving steam turbine (1), wherein the peak-shaving steam turbine (1) is connected to the steam outlet of the steam generator (4).

2. A thermal power unit according to claim 1, characterized in that: Also includes: A circulation pump (6); the circulation pump (6) is arranged between the high-temperature heat exchange medium storage tank (3) and the steam generator (4); The circulation pump (6) is arranged between the low-temperature heat exchange medium storage tank (2) and the heat exchanger (5).

3. A thermal power unit according to claim 1 or 2, characterized in that: The heat exchange medium is one or more of binary molten salt, volcanic rock, magnesia brick, silicone oil and concrete.

4. The thermal power unit according to claim 1, characterized in that: Also includes: a plurality of valves (15); The valve (15) is arranged between the outlet of the high-pressure cylinder (7) of the main steam turbine and the outlet of the high-temperature side of the heat exchanger (5); the valve (15) is arranged between the inlet of the steam mixer (10) and the outlet of the high-temperature side of the heat exchanger (5); the valve (15) is arranged between the outlet of the high-temperature side of the heat exchanger (5) and the inlet of the deaerator (13).

5. The thermal power unit according to claim 1 or 4, characterized in that: Also includes: a reheater (16), the inlet of which is in communication with the boiler (17); Its outlet is communicated with the inlet of the main steam turbine high-pressure cylinder (7).

6. The thermal power unit according to claim 1, characterized in that: Also includes: A condenser (11) whose inlet is connected to the outlet of the main turbine low-pressure cylinder (9); a low-pressure heater (12) whose inlet is connected to the outlet of the condenser (11); and whose outlet is connected to the deaerator (13).

7. The thermal power unit according to claim 6, characterized in that: Also includes: A valve (15) is arranged between the intermediate pressure cylinder (8) of the main steam turbine and the inlet of the deaerator (13).

8. A thermal storage peak-shaving method for a thermal power unit, used for a thermal power unit according to any one of claims 1 to 7, characterized in that ,include: During the off-peak period of electricity consumption, part of the steam generated by the thermal power unit heats the low-temperature heat exchange medium through the heat exchanger (5) to form a high-temperature heat exchange medium; the high-temperature heat exchange medium is stored in the high-temperature heat exchange medium storage tank (3); During the peak period of electricity consumption, the high-temperature heat exchange medium is transported to a steam generator (4) to obtain steam, and the steam is transported to a peak-shaving steam turbine (1) to generate electricity; The high-temperature heat exchange medium becomes a low-temperature heat exchange medium after passing through the steam generator (4), and the low-temperature heat exchange medium is stored in a low-temperature heat exchange medium storage tank (2).

9. The heat storage peak-shaving method for a thermal power unit according to claim 8, characterized in that: Also includes: The high-temperature heat exchange medium in the high-temperature heat exchange medium storage tank (3) enters the steam generator (4) through a circulation pump (6); The low-temperature heat exchange medium in the low-temperature heat exchange medium storage tank (2) is converted into the high-temperature heat exchange medium by passing through the heat exchanger (5) via a circulation pump (6).

10. A power generation system, characterized in that: A thermal power unit comprising any one of claims 1 to 7.

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