Molten salt heat storage steam supply system and steam supply method

Abstract

The present invention provides a molten salt heat storage steam supply system and a steam supply method, belonging to the field of molten salt heat storage technology. The molten salt heat storage steam supply system includes a storage tank, which is used to store molten salt. The molten salt heat storage steam supply system also includes a heat exchange device and a water supply device. The heat exchange device includes a plurality of heat exchange coils arranged in sequence along the height direction of the storage tank. The plurality of heat exchange coils are connected in series and are respectively wound around the outer wall of the storage tank. The uppermost heat exchange coil of the outer wall of the storage tank has a steam outlet; the water supply device includes a water supply pump and a plurality of water supply branches. The water supply pump is used to supply water to the water supply branch, and the plurality of water supply branches are connected one by one with the plurality of heat exchange coils. The above structure allows the molten salt in the storage tank to be divided into a plurality of molten salt heating layers correspondingly. By controlling the water supply of each water supply branch, the molten salt heating layer participating in the heating is controlled. The operation is simple, and it can be regulated according to the residual heat of different molten salt heating layers, so as to make full use of the heat of the molten salt and improve the heat utilization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of molten salt heat storage, and in particular to a molten salt heat storage steam supply system and a steam supply method. Background Art

[0002] There are various occasions in industry where steam is needed. At present, the main energy source for small-scale steam demand is electricity, that is, water is heated by an electric heater to increase the temperature of the water and then generate steam. The method of directly using electricity to heat water to generate steam has the advantage of quickly generating steam, but due to the high peak electricity price, the operating cost of the device that directly uses electricity to heat water to generate steam during the day is very high. Therefore, heat storage technology is usually used to store heat at night and release heat during the day to reduce the operating cost of the steam supply device.

[0003] Thermal storage technology uses thermal storage materials as a medium to store thermal energy such as solar thermal energy, geothermal energy, industrial waste heat, and low-grade waste heat, and releases it when needed. It strives to solve the problems caused by the mismatch between thermal energy supply and demand in time, space or intensity, and to maximize the energy utilization of the entire system. Molten salt thermal storage and steam supply technology is one of the commonly used thermal storage and steam supply technologies. Molten salt thermal storage and steam supply technology mainly stores heat through molten salt in the storage tank, transfers the heat of the molten salt to water through a heat exchanger, and then converts the water into steam.

[0004] At present, there are two main ways to set up the heat exchanger in the molten salt heat storage and steam supply technology: the first is to set the heat exchanger in the storage tank. This method has the problem of vibration of the heat exchanger and the risk of the working fluid flowing out of the heat exchanger and then flowing into the molten salt; the second is to set the heat exchanger on the outer wall of the storage tank. This method has the problem of large temperature difference between the upper and lower molten salt in the storage tank. In particular, the lower molten salt will solidify if it is heated by cold water all the time, which is not conducive to heat transfer. At the same time, the temperature of the lower molten salt rises very slowly during the next cycle of heat charging. When the upper molten salt reaches the upper limit of the use temperature, the temperature of the lower molten salt is still at a relatively low temperature, the molten salt does not release heat fully, and the heat utilization rate is low. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of insufficient heat release and low heat utilization rate of molten salt in the existing molten salt heat storage steam supply technology, and to provide a molten salt heat storage steam supply system and a steam supply method.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] A molten salt heat storage steam supply system, comprising a storage tank, wherein the storage tank is used to store molten salt, and the molten salt heat storage steam supply system further comprises:

[0008] A heat exchange device, the heat exchange device comprising a plurality of heat exchange coils sequentially arranged along the height direction of the storage tank, the plurality of heat exchange coils being connected in series and respectively wound around the outer side wall of the storage tank, the uppermost heat exchange coil on the outer side wall of the storage tank having a steam outlet;

[0009] A water supply device, the water supply device comprises a water supply pump and a plurality of water supply branches, the water supply pump is used to supply water to the water supply branches, and the plurality of water supply branches are connected to the plurality of heat exchange coils in a one-to-one correspondence.

[0010] In this scheme, water is supplied to the heat exchange device through the water supply device, and heat is supplied to the heat exchange device through the molten salt in the storage tank, and then the water is heated into steam through the heat exchange device. Multiple heat exchange coils are arranged in sequence along the height direction of the storage tank and connected in series, so that the molten salt in the storage tank is correspondingly divided into multiple molten salt heating layers, that is, each heat exchange coil corresponds to a molten salt heating layer; the water supply branches supply water to the heat exchange coils one by one, so that the heat utilization of different molten salt heating layers can be relatively independent; by controlling the water supply of each water supply branch, the molten salt heating layer involved in the heating is controlled, which is easy to operate and can be adjusted according to the residual heat of different molten salt heating layers, so as to make full use of the heat of the molten salt and improve the heat utilization rate.

[0011] Preferably, the water supply device further comprises a plurality of water supply valves, and the plurality of water supply valves are arranged one-to-one on the plurality of water supply branch pipes.

[0012] In this scheme, water supply valves and water supply branches are set one by one, and the water supply valves are used to control the water inlet of different water supply branches respectively, so as to realize the independent water supply of each water supply branch, and then control the water inlet of the corresponding heat exchange coil, realize the layered utilization of molten salt, make full use of the heat of each layer of molten salt, and improve the heat utilization rate.

[0013] Preferably, a plurality of the water supply branch pipes are connected in series, and the water supply branch pipe connected to the heat exchange coil at the bottom of the outer side wall of the storage tank is connected to the water supply pump.

[0014] In this solution, the water supply branches are connected in series, and the water supply pump is connected to the water inlet of the water supply branch corresponding to the bottom heat exchange coil. The water supply branch is configured as follows: the internal resistance of the water supply branch is smaller than the internal resistance of the adjacent next-level heat exchange coil, so that the water flow preferentially flows into the water supply branch, and then the water supply of different water supply branches is realized by opening and closing the water supply valves on each water supply branch. The series connection method can save the material consumption of the water supply branch and reduce the space occupied by the water supply branch. Among them, the adjacent next-level heat exchange coil refers to the heat exchange coil connected in series and located below the heat exchange coil connected to the water supply branch in the vertical direction.

[0015] Preferably, a plurality of the water supply branch pipes are connected in parallel, and the plurality of the water supply branch pipes are respectively connected to the water supply pumps.

[0016] In this solution, the water supply branches are connected in parallel and are supplied with water by water supply pumps respectively. The water inlet between each water supply branch is independent of each other and does not interfere with each other, which is convenient for operation.

[0017] Preferably, the molten salt heat storage steam supply system further includes a temperature control device, which includes a first temperature measuring component, the first temperature measuring component is connected to the steam outlet, and the first temperature measuring component is used to measure the temperature of the steam at the steam outlet.

[0018] In this solution, by setting a first temperature measuring element at the steam outlet, the temperature of the steam output by the molten salt heat storage steam supply system can be measured to determine whether the temperature of the steam is within the set temperature range. If the temperature is too high, the steam temperature can be lowered to reach the set value by reducing the number of molten salt heating layers involved in the heating; if the temperature is too low, the steam temperature can be increased to reach the set value by increasing the number of molten salt heating layers involved in the heating.

[0019] Preferably, the temperature control device includes a desuperheating water pump and a desuperheater, the desuperheater is connected to the steam outlet, and the desuperheating water pump is used to inject cold water into the desuperheater to reduce the temperature of the steam flowing through the desuperheater to a set temperature.

[0020] In this scheme, the steam output from the steam outlet flows through the desuperheater. When the temperature of the steam output from the steam outlet is too high, cold water can be injected into the desuperheater through a desuperheating water pump to reduce the temperature of the steam flowing through the desuperheater. This desuperheating method is low in cost and fast in desuperheating speed.

[0021] Preferably, the temperature control device also includes a cooling water pipe and a cooling valve, the two ends of the cooling water pipe are respectively connected to the cooling water pump and the cooler, the cooling valve is arranged on the cooling water pipe, and the cooling valve is used to control the water flow of the cooling water pipe.

[0022] In this scheme, the desuperheater and the desuperheater water pump are connected by a desuperheating water pipe, and the water flow through the desuperheating water pipe is controlled by a desuperheating valve. The water flow in the desuperheating water pipe can be controlled according to the difference between the steam temperature at the steam outlet and the set value, thereby controlling the amount of cold water injected into the desuperheater, so that the steam temperature reaches the set value faster and more accurately.

[0023] Preferably, the temperature control device further comprises a second temperature measuring component, the second temperature measuring component is connected to the desuperheater, and the second temperature measuring component is used to measure the temperature of the steam after being desuperheated by the desuperheater.

[0024] In this solution, the second temperature measuring element is used to measure the temperature of the steam after the desuperheater is cooled, thereby ensuring that the final output steam temperature reaches the set value and the accuracy of the output steam temperature is ensured. When the input steam temperature is too high, the steam temperature can be lowered by adjusting the water flow of the desuperheating water pipe, or by reducing the number of molten salt heating layers involved in the heating; when the steam temperature is too low, the steam temperature can be increased by increasing the number of molten salt heating layers involved in the heating.

[0025] A molten salt heat storage steam supply method comprises the following steps:

[0026] Step S1, providing the molten salt heat storage steam supply system as described above;

[0027] Step S2: The plurality of heat exchange coils are supplied with water in sequence from top to bottom.

[0028] In this scheme, water is first supplied to the heat exchange coil at the top of the outer wall of the storage tank in the vertical direction to make full use of the heat of the molten salt heating layer corresponding to this heat exchange coil. When the heat of this layer of molten salt is not enough to make the temperature of the output steam reach the set value, the water supply to this heat exchange coil is stopped and water is supplied to the adjacent next-level heat exchange coil. At this time, since the above two levels of heat exchange coils are connected in series, the heating path of the water flow is increased, the temperature of the output steam can be increased, and the waste heat of the top layer of molten salt can be utilized; and so on, until water is supplied to the bottom heat exchange coil. At this time, the water flows through all the heat exchange coils, making maximum use of the waste heat of each layer of molten salt, so that the heat of each layer of molten salt from top to bottom can be fully utilized, thereby improving the heat utilization rate of the molten salt.

[0029] Preferably, the molten salt heat storage steam supply system further includes a first temperature measuring component, which is used to measure the temperature of the steam at the steam outlet, and the step S2 includes:

[0030] Step S21, when the temperature of the steam at the steam outlet is lower than the set value for the first time, closing the water supply branch pipe connected to the uppermost heat exchange coil on the outer side wall of the storage tank;

[0031] Step S22, when the temperature of the steam at the steam outlet is lower than the set value for the second time, closing the other water supply branch pipe connected to the other heat exchange coil connected to the uppermost heat exchange coil on the outer side wall of the storage tank;

[0032] Step S23, and so on, until the water supply branch pipe connected to the heat exchange coil at the bottom of the outer wall of the storage tank is closed.

[0033] In this solution, the first temperature measuring component is used to reflect the temperature of the steam output from the steam outlet, and the water supply of each heat exchange coil is controlled accordingly to make the temperature of the output steam more accurate and meet the requirements. When the steam temperature at the steam outlet is lower than the set value for the first time, it means that the heat of the top molten salt heating layer is not enough to make the steam temperature reach the set value. At this time, the water supply of the top heat exchange coil is turned off, and the water supply of the adjacent next-level heat exchange coil is turned on. The molten salt corresponding to the next-level heat exchange coil has not undergone heat exchange and has a higher temperature. In addition, the water flows through the above-mentioned two-level heat exchange coil, which increases the water flow path and the heat exchange area, and can increase the steam temperature to the set value. When the steam temperature at the steam outlet is lower than the set value for the second time, it means that the heat of the top two layers of molten salt heating layers is insufficient. The heat is not enough to make the steam temperature reach the set value. At this time, it is necessary to close the water supply of the top two heat exchange coils and open the water supply of the adjacent next-level heat exchange coil. The water flows through the above three-level heat exchange coils, further increasing the water flow path and the heat exchange area, which can increase the steam temperature to the set value; and so on, until the water supply of the last level of heat exchange coil is opened and the water supply of all the heat exchange coils above it is closed. At this time, the water flows through all the heat exchange coils, the water flow path is the longest, the heat exchange area is the largest, and the steam temperature can be increased to the set value. The above water supply sequence maximizes the use of the heat of the molten salt and improves the heat utilization rate of the molten salt.

[0034] The positive and progressive effects of the present invention are:

[0035] The heat exchange device is supplied with water through the water supply device, and the heat exchange device is supplied with heat through the molten salt in the storage tank, and then the water is heated into steam through the heat exchange device. Multiple heat exchange coils are arranged in sequence along the height direction of the storage tank and connected in series, so that the molten salt in the storage tank is correspondingly divided into multiple molten salt heating layers, that is, each heat exchange coil corresponds to a molten salt heating layer; the water supply branches supply water to the heat exchange coils one by one, so that the heat utilization of different molten salt heating layers can be relatively independent; by controlling the water supply of each water supply branch, the molten salt heating layer involved in the heating is controlled, which is easy to operate and can be adjusted according to the residual heat of different molten salt heating layers, so as to make full use of the heat of the molten salt and improve the heat utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of a molten salt heat storage and steam supply system according to an embodiment of the present invention.

[0037] Figure 2 This is a flow chart of a molten salt heat storage and steam supply method according to an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] Storage tank 1

[0040] Heat exchange coil 2

[0041] Steam outlet 21

[0042] Feedwater pump 31

[0043] Water supply branch pipe 32

[0044] Water supply valve 33

[0045] Connecting pipe 34

[0046] The first temperature measuring element 41

[0047] Desuperheating water pump 42

[0048] Desuperheater 43

[0049] Cooling water pipe 44

[0050] Temperature reducing valve 45

[0051] The second temperature measuring element 46

[0052] Electric heater 5 DETAILED DESCRIPTION

[0053] The present invention will be described more clearly and completely below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments.

[0054] like Figure 1 As shown, the present embodiment provides a molten salt heat storage and steam supply system, including a storage tank 1, the storage tank 1 is used to store molten salt, the molten salt heat storage and steam supply system also includes a heat exchange device and a water supply device, the heat exchange device includes a plurality of heat exchange coils 2 arranged in sequence along the height direction of the storage tank 1, the plurality of heat exchange coils 2 are connected in series and are respectively wound around the outer wall of the storage tank 1, specifically, in the present embodiment, the heat exchange coils 2 are welded to the outer wall of the storage tank 1, and the uppermost heat exchange coil 2 on the outer wall of the storage tank 1 has a steam outlet 21; the water supply device includes a water supply pump 31 and a plurality of water supply branches 32, the water supply pump 31 is used to supply water to the water supply branch 32, and the plurality of water supply branch 32 is connected to the plurality of heat exchange coils 2 one by one.

[0055] The heat exchange device is supplied with water through the water supply device, and the heat exchange device is supplied with heat through the molten salt in the storage tank 1, and then the water is heated into steam through the heat exchange device. A plurality of heat exchange coils 2 are sequentially arranged along the height direction of the storage tank 1 and connected in series, so that the molten salt in the storage tank 1 is correspondingly divided into a plurality of molten salt heating layers, that is, each heat exchange coil 2 corresponds to a molten salt heating layer; the water supply branch pipes 32 respectively supply water to the heat exchange coils 2 one by one, so that the heat utilization of different molten salt heating layers can be relatively independent; by controlling the water supply of each water supply branch pipe 32, the molten salt heating layer involved in the heating is controlled, the operation is simple, and it can be adjusted according to the residual heat of different molten salt heating layers, so as to make full use of the heat of the molten salt and improve the heat utilization rate. At the same time, the heat exchange surface is put into the step, and the heat exchange is uniform, so that the temperature difference between the upper and lower molten salt in the storage tank 1 is small at the end of the heat release, and the molten salt at the bottom does not solidify, so as to avoid affecting the heat exchange rate due to the solidification of the molten salt. Furthermore, the heat exchange coil 2 is connected to the outer wall of the storage tank 1, so there is no risk of the heating medium flowing into the molten salt, and maintenance is convenient.

[0056] In this embodiment, the molten salt heat storage steam supply system further includes an electric heater 5, which is flange-connected to the storage tank 1. The heating end of the electric heater 5 is located in the storage tank 1 and is used to heat the molten salt in the storage tank 1. When the molten salt reaches the upper limit temperature of use, the heating is stopped and the heat is stored in the molten salt. The electric heater 5 can be used to heat and store heat in the molten salt using valley electricity at night and release heat during the day, thereby avoiding the high cost of steam supply caused by directly using peak electricity to heat the molten salt during the day.

[0057] In this embodiment, the water supply device also includes a plurality of water supply valves 33, and the plurality of water supply valves 33 are arranged one by one on the plurality of water supply branches 32, and then the water supply valves 33 are used to control the water inlet of different water supply branches 32 respectively, so as to realize the independent water supply of each water supply branch 32, and then control the water inlet of the corresponding heat exchange coil 2, so as to realize the layered utilization of molten salt, make full use of the heat of each layer of molten salt, and improve the heat utilization rate.

[0058] In this embodiment, a plurality of water supply branches 32 are connected in series, and the water supply branch 32 connected to the bottom heat exchange coil 2 of the outer wall of the storage tank 1 is connected to the water supply pump 31. The water supply branch 32 is configured such that the internal resistance of the water supply branch 32 is smaller than the internal resistance of the adjacent next-stage heat exchange coil 2, so that the water flow preferentially flows into the water supply branch 32, and then the water supply of different water supply branches 32 is realized by opening and closing the water supply valves 33 on each water supply branch 32. The series connection mode can save the material consumption of the water supply branch 32 and reduce the occupied space of the water supply branch 32. Among them, the adjacent next-stage heat exchange coil 2 refers to the heat exchange coil 2 connected in series and located below the heat exchange coil 2 connected to the water supply branch 32 in the vertical direction. Specifically in this embodiment, the water supply branch 32 is a straight pipe or a nearly straight pipe, and the water path is much shorter than the adjacent next-stage heat exchange coil 2, so the water path resistance of the water supply branch 32 is smaller than that of the next-stage heat exchange coil 2. In other embodiments, other structures may also be used to control the waterway resistance.

[0059] In this embodiment, the molten salt heat storage steam supply system further includes a plurality of connecting pipes 34, which are connected to the water supply branch pipes 32 one by one, and the two ends of the connecting pipes 34 are respectively connected to the water supply branch pipes 32 and the corresponding heat exchange coils 2. Specifically, the water supply branch pipe 32 has three connecting ports, which are respectively connected to the water supply branch pipes 32 and the connecting pipes 34 connected in series with the upper and lower water supply branch pipes 32, so that the water supply is more convenient and faster.

[0060] In other embodiments, multiple water supply branch pipes 32 can also be arranged in parallel. The multiple water supply branch pipes 32 are respectively connected to the water supply pumps 31, and are respectively supplied with water by the water supply pumps 31. The water inlet between each water supply branch pipe 32 is independent of each other and does not interfere with each other, which is convenient for operation.

[0061] In this embodiment, the molten salt heat storage steam supply system further includes a temperature control device, which includes a first temperature measuring element 41, which is connected to the steam outlet 21, and is used to measure the temperature of the steam at the steam outlet 21 to determine whether the temperature of the steam is within a set temperature range. If the temperature is too high, the steam temperature can be lowered to reach the set value by reducing the number of molten salt heating layers participating in the heating; if the temperature is too low, the steam temperature can be increased to reach the set value by increasing the number of molten salt heating layers participating in the heating.

[0062] In this embodiment, the temperature control device includes a desuperheating water pump 42 and a desuperheater 43. The desuperheater 43 is connected to the steam outlet 21. The desuperheating water pump 42 is used to inject cold water into the desuperheater 43 to reduce the temperature of the steam flowing through the desuperheater 43 to a set temperature. The steam output from the steam outlet 21 flows through the desuperheater 43. When the temperature of the steam output from the steam outlet 21 is too high, cold water can be injected into the desuperheater 43 by the desuperheating water pump 42 to reduce the temperature of the steam flowing through the desuperheater 43. Specifically, in this embodiment, the cold water channel and the steam channel in the desuperheater 43 are not connected to each other. This cooling method is low-cost and has a fast cooling speed. In other embodiments, other structures can also be used for cooling.

[0063] In this embodiment, the temperature control device further includes a cooling water pipe 44 and a cooling valve 45. The two ends of the cooling water pipe 44 are connected to the cooling water pump 42 and the desuperheater 43 respectively. The cooling valve 45 is arranged on the cooling water pipe 44. The cooling valve 45 is used to control the water flow of the cooling water pipe 44. The desuperheater 43 and the desuperheater pump 42 are connected through the cooling water pipe 44, and the water flow flowing through the cooling water pipe 44 is controlled by the cooling valve 45. The water flow of the cooling water pipe 44 can be controlled according to the difference between the steam temperature of the steam outlet 21 and the set value, thereby controlling the cold water injection amount of the desuperheater 43, so that the steam temperature reaches the set value faster and more accurately.

[0064] In this embodiment, the temperature control device further includes a second temperature measuring element 46, which is connected to the desuperheater 43. The second temperature measuring element 46 is used to measure the temperature of the steam after being desuperheated by the desuperheater 43, thereby ensuring that the final output steam temperature reaches the set value and the accuracy of the output steam temperature. When the input steam temperature is too high, the steam temperature can be lowered by adjusting the water flow of the desuperheating water pipe 44, or by reducing the number of molten salt heating layers participating in the heating; when the steam temperature is too low, the steam temperature can be increased by increasing the number of molten salt heating layers participating in the heating.

[0065] like Figure 2 As shown, this embodiment also provides a molten salt heat storage steam supply method, which includes the following steps:

[0066] Step S1, providing the molten salt heat storage steam supply system as described above;

[0067] Step S2: Multiple heat exchange coils 2 are supplied with water in order from top to bottom.

[0068] In the vertical direction, water is first supplied to the heat exchange coil 2 at the top of the outer wall of the storage tank 1 to make full use of the heat of the molten salt heating layer corresponding to this heat exchange coil 2. When the heat of this layer of molten salt is not enough to make the temperature of the output steam reach the set value, the water supply to this heat exchange coil 2 is stopped, and water is supplied to the adjacent next-level heat exchange coil 2. At this time, since the above-mentioned two-stage heat exchange coil 2 is connected in series, the heating path of the water flow is increased, the temperature of the output steam can be increased, and the waste heat of the top layer of molten salt can be utilized; and so on, until water is supplied to the bottom heat exchange coil. At this time, the water flows through all the heat exchange coils 2, and the waste heat of each layer of molten salt is utilized to the maximum extent, so that the heat of each layer of molten salt from top to bottom can be fully utilized, thereby improving the heat utilization rate of the molten salt.

[0069] In this embodiment, the molten salt heat storage steam supply system further includes a first temperature measuring element 41, which is used to measure the temperature of the steam at the steam outlet 21. Step S2 includes:

[0070] Step S21, when the temperature of the steam at the steam outlet 21 is lower than the set value for the first time, the water supply branch pipe 32 connected to the uppermost heat exchange coil 2 on the outer wall of the storage tank 1 is closed;

[0071] Step S22, when the temperature of the steam at the steam outlet 21 is lower than the set value for the second time, close another water supply branch pipe 32 connected to another heat exchange coil 2 connected to the uppermost heat exchange coil 2 on the outer side wall of the storage tank 1;

[0072] Step S23, and so on, until the water supply branch pipe 32 connected to the bottom heat exchange coil 2 on the outer wall of the storage tank 1 is closed.

[0073] The first temperature measuring component 41 is used to reflect the temperature of the steam output from the steam outlet 21, and the water supply of each heat exchange coil 2 is controlled accordingly to make the temperature of the output steam more accurate and meet the requirements. When the steam temperature at the steam outlet 21 is lower than the set value for the first time, it means that the heat of the top molten salt heating layer is not enough to make the steam temperature reach the set value. At this time, the water supply of the top heat exchange coil 2 is turned off, and the water supply of the adjacent next-level heat exchange coil 2 is turned on. The molten salt corresponding to the next-level heat exchange coil 2 has not undergone heat exchange and has a higher temperature. In addition, the water flows through the above-mentioned two-level heat exchange coil 2, which increases the water flow path and the heat exchange area, and can increase the steam temperature to the set value. When the steam temperature at the steam outlet 21 is lower than the set value for the second time, it means that the top two layers of molten salt heating are insufficient. The heat of the layer is not enough to make the steam temperature reach the set value. At this time, it is necessary to close the water supply of the top two heat exchange coils 2 and open the water supply of the adjacent next-level heat exchange coil 2. The water flows through the above three-level heat exchange coil 2, further increasing the water flow path and increasing the heat exchange area, which can increase the temperature of the steam to the set value; and so on, until the water supply of the last level of heat exchange coil 2 is opened, and the water supply of all the heat exchange coils 2 above it is closed. At this time, the water flows through all the heat exchange coils 2, the water flow path is the longest, the heat exchange area is the largest, and the steam temperature can be increased to the set value. The above water supply sequence maximizes the use of the heat of the molten salt and improves the heat utilization rate of the molten salt. When the steam temperature at the steam outlet 21 is lower than the set value again, the heat release ends.

[0074] The molten salt heat storage and steam supply method of this embodiment can invest the least heating surface when the overall temperature of the molten salt in the storage tank 1 is the highest and the heat storage capacity is the largest, and gradually invest more heating surface when the overall temperature of the molten salt in the storage tank 1 gradually decreases and the heat storage capacity gradually decreases, so that the heat release of the molten salt can be more uniform; at the same time, the closer the molten salt is to the bottom, the shorter the time it participates in heat release, which can avoid the solidification of the molten salt in the lower part of the traditional method due to continuous heating of cold water.

[0075] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A molten salt heat storage steam supply system, comprising a storage tank, wherein the storage tank is used to store molten salt, characterized in that: The molten salt heat storage steam supply system also includes: A heat exchange device, the heat exchange device comprising a plurality of heat exchange coils sequentially arranged along the height direction of the storage tank, the plurality of heat exchange coils being connected in series and respectively wound around the outer side wall of the storage tank, the uppermost heat exchange coil on the outer side wall of the storage tank having a steam outlet; A water supply device, the water supply device comprising a water supply pump and a plurality of water supply branches, the water supply pump is used to supply water to the water supply branches, the plurality of water supply branches are connected to the plurality of heat exchange coils in a one-to-one correspondence, the water supply device further comprising a plurality of water supply valves, the plurality of water supply valves are arranged on the plurality of water supply branches in a one-to-one correspondence; A temperature control device, the temperature control device comprising a first temperature measuring element, the first temperature measuring element is connected to the steam outlet, and the first temperature measuring element is used to measure the temperature of the steam at the steam outlet, The molten salt heat storage steam supply system controls the opening and closing of the plurality of water supply valves according to the detected temperature of the first temperature measuring component so that the water supply pump supplies water to the corresponding heat exchange coil.

2. The molten salt heat storage steam supply system according to claim 1, characterized in that: A plurality of water supply branch pipes are connected in series, and the water supply branch pipe connected to the lowest heat exchange coil on the outer wall of the storage tank is connected to the water supply pump. The water supply branch pipe is configured such that the internal resistance of the water supply branch pipe is smaller than the internal resistance of the adjacent next-level heat exchange coil.

3. The molten salt heat storage steam supply system according to claim 1, characterized in that: The plurality of water supply branch pipes are connected in parallel, and the plurality of water supply branch pipes are respectively connected to the water supply pumps.

4. The molten salt heat storage steam supply system according to claim 1, characterized in that: The temperature control device also includes a desuperheating water pump and a desuperheater. The desuperheater is connected to the steam outlet. The desuperheating water pump is used to inject cold water into the desuperheater to reduce the temperature of the steam flowing through the desuperheater to a set temperature.

5. The molten salt heat storage steam supply system according to claim 4, characterized in that: The temperature control device also includes a cooling water pipe and a cooling valve. The two ends of the cooling water pipe are respectively connected to the cooling water pump and the cooler. The cooling valve is arranged on the cooling water pipe and is used to control the water flow of the cooling water pipe.

6. The molten salt heat storage steam supply system according to claim 4, characterized in that: The temperature control device also includes a second temperature measuring component, which is connected to the desuperheater and is used to measure the temperature of the steam after being desuperheated by the desuperheater.

7. A molten salt heat storage steam supply method, characterized in that: The following steps are involved: Step S1, providing a molten salt heat storage and steam supply system as described in any one of claims 1 to 6; Step S2, the plurality of heat exchange coils are supplied with water in order from top to bottom; The molten salt heat storage steam supply system further includes a first temperature measuring component, which is used to measure the temperature of the steam at the steam outlet. The step S2 includes: Step S21, when the temperature of the steam at the steam outlet is lower than the set value for the first time, closing the water supply branch pipe connected to the uppermost heat exchange coil on the outer side wall of the storage tank; Step S22, when the temperature of the steam at the steam outlet is lower than the set value for the second time, closing the other water supply branch pipe connected to the other heat exchange coil connected to the uppermost heat exchange coil on the outer side wall of the storage tank; Step S23, and so on, until the water supply branch pipe connected to the heat exchange coil at the bottom of the outer wall of the storage tank is closed.

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