Tower type photo-thermal power station fused salt heat collection system and operation method thereof

Abstract

The invention belongs to the technical field of fused salt heat collection systems, and provides a tower type photo-thermal power station fused salt heat collection system and an operation method thereof.The tower type photo-thermal power station fused salt heat collection system comprises a cold fused salt tank, a cold fused salt pump connected with the cold fused salt tank, a cold fused salt pump outlet branch pipe, a cold fused salt pump outlet main pipe, an ascending pipe, a heat absorber and an outlet buffer tank; a shut-off valve is arranged on a heat absorber deflation pipeline, and a cold molten salt pump outlet branch pipe, a cold molten salt pump outlet mother pipe, an ascending pipe, a heat absorber and a heat absorber deflation pipeline which are sequentially connected from a cold molten salt tank to an outlet buffer tank are arranged in a mode that the height is gradually increased. The shut-off valve on the deflation pipeline of the heat absorber also serves as a deflation valve of the whole pipeline system, and the arrangement mode that the height of the pipeline of the coupling pipeline equipment combination system is gradually increased is adopted, so that the phenomenon that a liquid bag is formed when the pipeline system normally operates is avoided, a salt dredging tank and a salt dredging pump do not need to be independently arranged in a storage tank area, and cost is reduced; the cold molten salt tank has the functions of storing molten salt and receiving and draining salt.

Description

Technical Field

[0001] The present invention belongs to the technical field of molten salt thermal collection systems, and in particular relates to a molten salt thermal collection system for a tower-type solar thermal power station and an operation method thereof. Background Art

[0002] Tower solar thermal power generation generally uses molten salt as a heat absorption and storage medium. The heat absorption process of tower molten salt solar thermal power generation is to extract cold molten salt at about 290°C from the cold salt tank and transport it to the absorber at the top of the tower through the riser. The cold molten salt absorbs the radiation energy of the mirror field in the absorber and is heated to about 565°C. Then it flows back to the hot salt tank through the downcomer with the help of gravity.

[0003] The layout of the molten salt heat collection system of a traditional tower-type solar thermal power station is that the pipeline is first bent downward from the outlet of the cold molten salt pump and then connected to the absorber upward, thus forming a liquid bag. Since the lowest point of the liquid bag is lower than the top of the cold molten salt tank, a salt-discharging tank lower than the liquid bag must be separately arranged in the tank area to receive the salt discharged from the liquid bag. In addition, a salt-discharging pump and electric heating of the salt-discharging pipeline are required, which is costly, and the operation and maintenance process adds the process of starting and stopping the salt-discharging pump and the electric heating of the salt-discharging pipeline, which is relatively complicated and inconvenient. Among them, the patent CN217031638U "A molten salt circulation system for a tower-type solar thermal power station" includes a cold salt tank, an absorber assembly and a hot salt tank. The cold salt tank is connected to the absorber assembly through an ascending pipe, and the absorber assembly is connected to the hot salt tank through a descending pipe. An ascending regulating valve is arranged on the ascending pipe, and a descending regulating valve is arranged on the descending pipe. It does not involve the pipeline equipment combination at the outlet of the molten salt pump, nor does it involve the coupling relationship between the pipeline equipment combination and its pipeline layout type. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a molten salt heat collection system for a tower-type solar thermal power station and an operation method thereof, wherein the cold molten salt pump outlet branch pipe, the cold molten salt pump outlet main pipe, the riser pipe and the absorber vent pipe between the cold molten salt tank and the outlet buffer tank are arranged in a gradually increasing height. The shut-off valve on the absorber vent pipe also serves as the vent valve of the entire pipeline system. The molten salt heat collection system adopts a layout pattern in which the pipeline height of the coupled pipeline equipment combination system is gradually increased, which avoids the formation of liquid bags during the normal operation of the pipeline system, and does not need to be separately provided with a salt drain tank and a salt drain pump in the tank storage area, thereby reducing costs.

[0005] In order to achieve the above-mentioned object, in the first aspect, the present invention provides a molten salt heat collection system for a tower-type solar thermal power station, which adopts the following technical scheme:

[0006] A molten salt heat collection system for a tower-type solar thermal power station, comprising a cold molten salt tank, a cold molten salt pump connected to the cold molten salt tank, a cold molten salt pump outlet branch connected to the cold molten salt pump, a cold molten salt pump outlet main pipe connected to the cold molten salt pump outlet branch, a riser connected to the cold molten salt pump outlet main pipe, a heat absorber connected to the riser, and an outlet buffer tank connected to the heat absorber at least through a heat absorber venting pipe;

[0007] A shut-off valve is provided on the absorber venting pipeline, and the cold molten salt pump outlet branch pipe, the cold molten salt pump outlet main pipe, the riser, the absorber and the absorber venting pipeline are sequentially connected from the cold molten salt tank to the outlet buffer tank, and are arranged in a gradually increasing height.

[0008] Furthermore, the absorber and the outlet buffer tank are connected via a pipeline from the absorber salt outlet to the outlet buffer tank, and the pipelines from the cold molten salt tank to the outlet buffer tank, the outlet branch pipe of the cold molten salt pump, the outlet main pipe of the cold molten salt pump, the riser to the absorber salt outlet to the outlet buffer tank, also adopt a layout with gradually increasing heights.

[0009] Furthermore, the outlet branch of the cold molten salt pump is connected to the minimum flow recirculation branch through a tee; a regulating valve is provided on the minimum flow recirculation branch, and the minimum flow recirculation branch is connected to the cold molten salt tank; the minimum flow recirculation branch from the tee to the cold molten salt tank, and then to the cold molten salt tank are connected in sequence, and a layout with a gradually decreasing height is adopted.

[0010] Furthermore, the minimum flow recirculation branch pipe is connected to the cold molten salt tank through a minimum flow recirculation main pipe; a vacuum breaking hole is provided on the pipe section of the minimum flow recirculation main pipe inserted into the cold molten salt tank; the vacuum breaking hole is located below the top of the cold molten salt tank and above the highest liquid level of the cold molten salt tank.

[0011] Furthermore, a check valve and a shut-off valve are sequentially arranged on the outlet branch of the cold molten salt pump along the outlet flow direction of the pump; the tee connecting the outlet branch of the cold molten salt pump and the minimum flow recirculation branch is located between the check valve and the shut-off valve on the outlet branch of the cold molten salt pump.

[0012] Furthermore, a plurality of cold molten salt pumps are connected to the cold molten salt tank, each cold molten salt pump is respectively connected to a cold molten salt pump outlet branch pipe, and a plurality of cold molten salt pump outlet branch pipes are commonly connected to a cold molten salt pump outlet mother pipe.

[0013] Furthermore, a first flow meter is arranged on the outlet main pipe of the cold molten salt pump; the outlet main pipe of the cold molten salt pump is connected to a riser, and a fifth regulating valve and a second flow meter are arranged on the pipeline between the riser and the heat absorber.

[0014] Furthermore, the outlet buffer tank is connected to the downcomer, and a fifth shut-off valve and a fourth regulating valve are provided on the downcomer; the downcomer is connected to the hot molten salt tank through a downcomer main line, and a sixth shut-off valve is provided on the downcomer main line; the downcomer is connected to the cold molten salt tank through a downcomer bypass, and a seventh shut-off valve is provided on the downcomer bypass.

[0015] Furthermore, a downcomer salt filling main pipe is provided between the cold molten salt pump outlet main pipe and the downcomer, and a fourth shut-off valve is provided on the downcomer salt filling main pipe.

[0016] Furthermore, a heat absorber salt filling main pipe is arranged between the ascending pipe and the downcomer, and a ninth shut-off valve is arranged on the heat absorber salt filling main pipe; the heat absorber salt filling main pipe is connected to the heat absorber through a heat absorber salt filling upper salt pipe, and a tenth shut-off valve is arranged on the heat absorber salt filling upper salt pipe.

[0017] In order to achieve the above-mentioned purpose, in a second aspect, the present invention also provides a method for operating a molten salt collector system of a tower-type solar thermal power station, which adopts the following technical solution:

[0018] A method for operating a molten salt thermal collection system of a tower-type solar thermal power station uses the molten salt thermal collection system of the tower-type solar thermal power station as described in the first aspect, including: the shut-off valve on the absorber venting pipeline also serves as the venting valve of the entire system.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In the present invention, a shut-off valve is arranged on the venting pipeline of the heat absorber, and the outlet branch pipe of the cold molten salt pump, the outlet main pipe of the cold molten salt pump, the riser, and the venting pipeline from the heat absorber to the heat absorber are connected in sequence, and a layout type with gradually increasing height is adopted; the shut-off valve on the venting pipeline of the heat absorber also serves as the venting valve of the entire pipeline system, and a layout type with gradually increasing pipeline height of the coupled pipeline equipment combination system is adopted, thereby avoiding the formation of liquid bags during normal operation of the pipeline system, and there is no need to separately set up a salt draining tank and a salt draining pump in the storage tank area, thereby reducing costs, and all the drained salt of the cold molten salt pump outlet pipeline system can be directly drained into the cold molten salt tank.

[0021] 2. In the present invention, a vacuum breaking hole is provided on the pipe section of the minimum flow recirculation mother pipe inserted into the cold molten salt tank. When the last running molten salt pump is shut down, the air or nitrogen in the tank enters the minimum flow recirculation mother pipe of the pump through the vacuum breaking hole, and then enters the pump outlet branch pipe through the regulating valve, thereby destroying the vacuum behind the check valve caused by the sudden stop of the pump, avoiding the gasification of the molten salt caused by the sudden drop in the molten salt pressure and the resulting gas-liquid two-phase flow impact, salt hammer hitting the valve, pipeline vibration, sudden increase in structural load and other problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0023] Figure 1 This is a system schematic diagram of Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the cold molten salt pump outlet pipeline arrangement of Example 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the pipeline arrangement between the outlet of the cold molten salt pump and the flow meter on the outlet mother pipe of the cold molten salt pump in Example 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of a system with a vacuum breaking hole according to Example 1 of the present invention;

[0027] Figure 5 This is a schematic diagram of the vacuum breaking hole structure of Example 1 of the present invention;

[0028] Among them, 1A, the first cold molten salt pump; 1B, the second cold molten salt pump; 1C, the third cold molten salt pump; 2A, the first check valve; 2B, the second check valve; 2C, the third check valve; 3A, the first shut-off valve; 3B, the second shut-off valve; 3C, the third shut-off valve; 4A, the first regulating valve; 4B, the second regulating valve; 4C, the third regulating valve; 5, the fourth shut-off valve; 6, the fifth shut-off valve; 7, the fourth regulating valve; 8, the sixth shut-off valve; 9, the seventh shut-off valve; 10, the eighth shut-off valve; 11, the ninth shut-off valve; 12, the tenth shut-off valve; 13, the eleventh shut-off valve; 14, the fifth regulating valve; 16A, the first three-way; 16B, the second three-way; 16C, the third three-way; 17, the minimum flow recirculation main pipe of the pump; 17A, the first minimum flow recirculation branch pipe; 17B, the second minimum flow recirculation branch pipe ; 17C, the third minimum flow recirculation branch; 21, the first flow meter; 22, the second flow meter; 31, the cold molten salt tank; 32, the hot molten salt tank; 33, the absorber; 34, the outlet buffer tank; 61A, the first cold molten salt pump outlet branch; 61B, the second cold molten salt pump outlet branch; 61C, the third cold molten salt pump outlet branch; 62, the cold molten salt pump outlet main pipe; 63, the riser; 64, the pipeline from the absorber to the outlet buffer tank; 71, the downcomer; 72, the downcomer bypass; 73, the downcomer main line; 81, the downcomer salt filling main pipe; 91, the absorber salt filling main pipe; 92, the absorber salt filling and salt supply pipeline; 93, the absorber venting pipeline; N1, the first connection port; N2, the second connection port; N3, the third connection port; N4, the fourth connection port; N5, the fifth connection port; N6, the sixth connection port. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0031] Embodiment 1:

[0032] When it is near night or the incident energy of sunlight is insufficient, the absorber enters the shutdown state. In order to reduce the heat loss of the entire system and prevent the solidification of molten salt equipment and pipelines and cause safety accidents, the molten salt in the entire system including the absorber, riser, and downcomer will be drained into the cold molten salt tank, and the entire system will be emptied. The system will be refilled with salt the next day and enter the normal operation mode. The tower solar thermal power generation unit repeats the process of salt filling and salt draining every day.

[0033] In order to complete the debugging and operation of the cold molten salt pump, start-up of the pump, operation of multiple pumps in parallel, daily salt filling and salt removal of the absorber in one system, it is necessary to design a scientific, economical and reasonable cold molten salt pump outlet pipeline system for the tower solar thermal power station and its debugging and operation method.

[0034] On the one hand, when starting up, a venting system needs to be set up at the highest point of the pipeline layout, and the venting system includes a venting valve, a venting pipeline, etc.; on the other hand, when stopping operation, a salt release system needs to be reasonably set up at the low point of the pipeline layout, and the salt release system includes a salt release valve, a salt release pipeline, etc. However, the venting pipeline and the salt release pipeline are both pipelines with smaller diameters. During normal operation, when the venting valve and the salt release valve are closed, there is a flow dead zone between the above-mentioned venting valve, the salt release valve and the main pipeline, which objectively increases the risk of molten salt solidification in this dead zone during operation.

[0035] In order to measure the flow rate of molten salt, expensive ultrasonic flowmeters are usually configured. The use of different combinations of pipeline equipment (such as valves, flowmeters, etc.) at the outlet of the cold molten salt pump, as well as different pipeline layout methods, plays a critical and decisive role in the functional realization of the cold molten salt pump outlet pipeline system of the tower thermal power station. In order to reduce the project investment of the tower thermal power station, the number of pipeline equipment should be minimized while ensuring that the required functions can be achieved. In the past, the cold molten salt pump outlet pipeline system of the tower thermal power station was relatively complex, and failed to combine the combination of pipeline equipment and pipeline layout of the cold molten salt pump outlet. Therefore, multiple sets of expensive valves and flowmeters were set up, resulting in a high investment cost of the tower thermal power station, which in turn led to poor economic efficiency of the tower thermal power station project.

[0036] In order to solve at least one of the above problems, Figure 1 As shown, this embodiment provides a tower-type solar thermal power station molten salt heat collection system, including a cold molten salt pump outlet pump valve subsystem, a heat absorber riser subsystem, a downcomer salt filling subsystem, a heat absorber salt filling subsystem and a downcomer system. The number of cold molten salt pumps ≥ 1, Figure 1 Take three cold molten salt pumps as an example.

[0037] The cold molten salt pump outlet pump valve subsystem includes a first cold molten salt pump 1A, a second cold molten salt pump 1B and a third cold molten salt pump 1C; the first cold molten salt pump 1A, the second cold molten salt pump 1B and the third cold molten salt pump 1C are connected to the cold molten salt tank 31 through a first connection port N1, a second connection port N2 and a third connection port N3 located on the cold molten salt tank 31, respectively. The first cold molten salt pump 1A, the second cold molten salt pump 1B and the third cold molten salt pump 1C are respectively connected to the first cold molten salt pump outlet branch 61A, the second cold molten salt pump outlet branch 61B and the third cold molten salt pump outlet branch 61C; the first cold molten salt pump outlet branch 61A, the second cold molten salt pump outlet branch 61B and the third cold molten salt pump outlet branch 61C are respectively provided with a first check valve 2A, a second check valve 2B and a third check valve 2C at one end close to the cold molten salt tank 31; the first cold molten salt pump outlet branch 61A, the second cold molten salt pump outlet branch 61B and the third cold molten salt pump outlet branch 61C are respectively provided with a first check valve 2A, a second check valve 2B and a third check valve 2C. On the outlet branch pipe 61C, at one end away from the cold molten salt tank 31, the first shut-off valve 3A, the second shut-off valve 3B and the third shut-off valve 3C are respectively provided; the first cold molten salt pump outlet branch pipe 61A, the second cold molten salt pump outlet branch pipe 61B and the third cold molten salt pump outlet branch pipe 61C are respectively connected with the first regulating valve 4A, the second regulating valve 4B and the third regulating valve 4C through the first three-way 16A, the second three-way 16B and the third three-way 16C; the first regulating valve 4A, the second regulating valve 4B and the third regulating valve 4C are connected in parallel through the pipeline and connected to the cold molten salt tank 31 through the fourth connecting port N4. The first three-way 16A is located between the first check valve 2A and the first shut-off valve 3A, the second three-way 16B is located between the second check valve 2B and the second shut-off valve 3B, and the third three-way 16C is located between the third check valve 2C and the third shut-off valve 3C.

[0038] The first cold molten salt pump outlet branch 61A is connected to the first minimum flow recirculation branch 17A through the first tee 16A, and the first regulating valve 4A is arranged on the first minimum flow recirculation branch 17A. The second cold molten salt pump outlet branch 61B is connected to the second minimum flow recirculation branch 17B through the second tee 16B, and the second regulating valve 4B is arranged on the second minimum flow recirculation branch 17B. The third cold molten salt pump outlet branch 61C is connected to the third minimum flow recirculation branch 17C through the third tee 16C, and the third regulating valve 4C is arranged on the third minimum flow recirculation branch 17C.

[0039] The first minimum flow recirculation branch 17A, the second minimum flow recirculation branch 17B and the third minimum flow recirculation branch 17C are connected to a minimum flow recirculation main pipe 17 of a pump; the minimum flow recirculation main pipe 17 of the pump is connected to the cold molten salt storage tank 31 through a fourth connection port N4.

[0040] The first cold molten salt pump outlet branch pipe 61A, the second cold molten salt pump outlet branch pipe 61B and the third cold molten salt pump outlet branch pipe 61C are connected in parallel and are connected to the cold molten salt pump outlet main pipe 62 after being combined. The cold molten salt pump outlet main pipe 62 is connected to the riser 63; the cold molten salt pump outlet main pipe 62 is provided with a first flow meter 21.

[0041] The absorber riser subsystem includes a riser 63 connected to the cold molten salt pump outlet main pipe 62, a fifth regulating valve 14 arranged between the absorber 33 and the first flow meter 21, a second flow meter 22 arranged between the absorber 33 and the first flow meter 21, the absorber 33, a pipeline 64 from the absorber salt outlet to the outlet buffer tank, and the outlet buffer tank 34.

[0042] The downcomer salt filling subsystem includes a downcomer salt filling mother pipe 81 and a fourth shut-off valve 5 arranged on the downcomer salt filling mother pipe 81. The downcomer salt filling subsystem is connected to the cold molten salt pump outlet mother pipe 62 and is connected in parallel with the riser 63 through a tee.

[0043] The absorber salt filling subsystem includes an absorber salt filling main pipe 91, an absorber salt filling and upper salt pipe 92, an absorber venting pipe 93, an eighth shut-off valve 10 arranged at the cold end of the absorber salt filling main pipe 91, a ninth shut-off valve 11 arranged at the hot end of the absorber salt filling main pipe 91, a tenth shut-off valve 12 arranged on the absorber salt filling and upper salt pipe 92, and an eleventh shut-off valve 13 arranged on the absorber venting pipe 93. One end of the absorber salt filling main pipe 91 is connected to the eighth shut-off valve 10, and the other end is respectively connected to the absorber salt filling and salting pipeline 92 and the ninth shut-off valve 11; one end of the absorber salt filling and salting pipeline 92 is connected to the absorber salt filling main pipe 91, and the other end is connected to the absorber 33; one end of the absorber venting pipeline 93 is connected to the absorber 33, and the other end is connected to the outlet buffer tank 34; in addition to being connected through the absorber venting pipeline 93, the outlet buffer tank 34 and the absorber 33 are also connected through a pipeline 64 from the absorber salt outlet to the outlet buffer tank.

[0044] The downcomer subsystem includes a downcomer 71 , a fifth shut-off valve 6 , a fourth regulating valve 7 , a downcomer main line 73 , a sixth shut-off valve 8 , a downcomer bypass 72 and a seventh shut-off valve 9 .

[0045] The downcomer 71 is connected to the outlet buffer tank 34, the end of the ninth shut-off valve 11 away from the eighth shut-off valve 10 is connected to the downcomer 71, and the two ends of the downcomer salt filling main pipe 81 are respectively connected to the cold molten salt pump outlet main pipe 62 and the downcomer 71; the fifth shut-off valve 6 and the fourth regulating valve 7 are arranged on the downcomer 71; the end of the fourth regulating valve 7 away from the fifth shut-off valve 6 is connected to the downcomer bypass 72 and the downcomer main road 73 through the downcomer 71, wherein the downcomer bypass 72 and the downcomer main road 73 are connected in parallel; the downcomer bypass 72 is connected to the cold molten salt tank 31 through the fifth connecting port N5, and the downcomer main road 73 is connected to the hot molten salt tank 32 through the sixth connecting port N6; the sixth shut-off valve 8 is arranged on the downcomer main road 73, and the seventh shut-off valve 9 is arranged on the downcomer bypass 72.

[0046] In some embodiments, Figure 2 and Figure 3 As shown, a piping system arrangement is provided for use with the cold molten salt pump outlet pump valve subsystem. The outlet pipe of the cold molten salt pump is connected in a horizontal direction, and then a check valve and a tee for recycling are arranged in sequence on the horizontal pipe. The third end of the tee for recycling is connected to a minimum flow recycling branch in a horizontal direction. The minimum flow recycling branch is inserted into the cold molten salt storage tank 31 downward after passing through at least one elbow.

[0047] From the outlet of the cold molten salt storage tank 31 to the heat absorber 33, a layout with gradually increasing height is adopted, that is, starting from the outlet of the cold molten salt storage tank 31, as the pipe section is extended, the elevation of each pipe section gradually increases or at least remains horizontal until it reaches the inlet of the heat absorber 33.

[0048] From the heat absorber 33 to the outlet buffer tank 34, a layout with gradually increasing height is adopted, that is, the venting pipeline at the outlet of the heat absorber 33 gradually rises or at least remains horizontal until it is connected to the inlet of the outlet buffer tank 34. Therefore, among all the valves in the pipeline system from the outlet of the cold molten salt pump to the outlet buffer tank, the eleventh shut-off valve 13 at the outlet of the heat absorber 33 is the valve with the highest arrangement height, and the eleventh shut-off valve 13 also serves as the venting valve of the entire pipeline system, that is, the eleventh shut-off valve 13 used for venting the outlet of the heat absorber 33 also has the function of venting the entire pipeline system.

[0049] From the tee for recycling to the cold molten salt storage tank 31, a layout with gradually decreasing height is adopted, that is, starting from the tee for recycling, as the pipe section is extended, the elevation of each pipe section is gradually reduced or at least kept horizontal until it is connected to the cold molten salt storage tank 31.

[0050] According to the above arrangement, in the pipeline system from the outlet of the cold molten salt pump to the outlet buffer tank and / or the cold molten salt tank, the regulating valve on the minimum flow recirculation branch is the valve with the lowest arrangement height among all the valves in the pipeline system; therefore, the regulating valve on the minimum flow recirculation branch also serves as the salt discharge valve of the entire pipeline system, that is, the minimum flow recirculation branch also has the function of a salt discharge pipeline.

[0051] In the traditional arrangement, starting from the outlet of the molten salt pump, the pipeline is first bent downward and then connected to the heat absorber upward, thereby forming a liquid bag. Since the lowest point of the liquid bag is lower than the top of the cold molten salt tank, a salt discharge tank lower than the position of the liquid bag must be separately set up in the storage tank area to receive the salt discharged from the liquid bag. In this embodiment, due to the arrangement type in which the pipeline height of the coupled pipeline equipment combination system is gradually increased, a liquid bag is not formed when the pipeline system is operating normally, and there is no need to separately set up a salt discharge tank and a salt discharge pump in the storage tank area. All the discharged salt in the cold molten salt pump outlet pipeline system can be directly discharged to the cold molten salt tank, that is, the cold molten salt tank has the functions of storing molten salt and receiving discharged salt.

[0052] Specifically, when a molten salt pump stops running, the interlock opens the regulating valve of the minimum flow recirculation branch corresponding to the molten salt pump on the same side, thereby effectively reducing the pipeline vibration caused by salt hammer; the salt hammer effect refers to the sudden change in the flow rate of molten salt in a pressurized molten salt pipeline due to some external reasons (such as sudden closure of the valve, sudden shutdown of the molten salt pump), which causes shock waves and causes the pipeline to vibrate under force. The regulating valve of the minimum flow recirculation branch has a quick opening function; the molten salt in the pipeline system can rely on gravity to flow into the cold molten salt tank through the regulating valve of the minimum flow recirculation branch arranged at the lowest point of the entire pipeline system, thereby minimizing the probability of intermittent flow of the molten salt column, thereby minimizing the probability of gas-liquid two-phase flow impact, thereby minimizing the pipeline vibration caused by salt hammer and reducing the damage and failure of the pipeline system caused by salt hammer hitting the valve.

[0053] The heat absorber salt filling mother pipe 91 is arranged close to the heat absorber, and the downcomer salt filling mother pipe 81 is arranged close to the fifth shut-off valve. Further, the heat absorber salt filling mother pipe 91 is more than 30 meters higher than the downcomer salt filling mother pipe 81.

[0054] Embodiment 2:

[0055] This embodiment provides an operation method of a molten salt thermal collection system of a tower-type solar thermal power station, using the molten salt thermal collection system of a tower-type solar thermal power station as described in Embodiment 1, including: an eleventh shut-off valve 13 also serves as a vent valve for the entire system.

[0056] Embodiment 3:

[0057] This embodiment provides a method for operating a molten salt collector system of a tower-type CSP power station, using the molten salt collector system of a tower-type CSP power station described in Example 1 and / or the method in Example 2, to realize the startup of a single molten salt pump, and to start the first molten salt pump. Taking the first cold molten salt pump 1A as an example, the startup of the first cold molten salt pump 1A is carried out according to the following contents:

[0058] When the first cold molten salt pump 1A is turned on, the first regulating valve 4A on the minimum flow recirculation branch on the same side is fully opened as the first cold molten salt pump 1A is started; at the same time, the first shut-off valve 3A at the pump outlet on the same side is opened as the first cold molten salt pump 1A is started;

[0059] During the load increase process of the first cold molten salt pump 1A, the first regulating valve 4A is remotely operated according to the flow rate of the cold molten salt pump outlet main pipe flowmeter, and its adjustment opening is gradually closed. When the flow rate of the first cold molten salt pump 1A on the same side (converted according to the flow rate measured by the first flowmeter 21) reaches or exceeds a certain set value, the first regulating valve 4A is closed.

[0060] The specific conversion examples are as follows:

[0061] Since the molten salt flow rate of the cold molten salt pump = the molten salt flow rate measured by the first flowmeter 21 + the molten salt flow rate flowing into the cold molten salt tank through the first regulating valve 4A, when the flow rate measured by the first flowmeter 21 is ≥ the minimum flow rate of a cold molten salt pump (for example, 15% of the rated flow rate of a cold molten salt pump), it can be concluded that the molten salt flow rate of the cold molten salt pump is ≥ the minimum flow rate of a cold molten salt pump (for example, 15% of the rated flow rate of a cold molten salt pump), thereby concluding that the first regulating valve 4A can be gradually closed until it is closed.

[0062] Embodiment 4:

[0063] This embodiment provides a method for operating a molten salt collector system of a tower-type CSP power station, using the molten salt collector system of a tower-type CSP power station described in Example 1, the method in Example 2, and / or the method in Example 3, to implement a method for debugging a molten salt pump. When debugging a molten salt pump, when debugging a first cold molten salt pump 1A, the second cold molten salt pump 1B and the third cold molten salt pump 1C are in a shutdown state, and the debugging of the first cold molten salt pump 1A is carried out according to the following contents:

[0064] The first cold molten salt pump 1A is started according to the starting method of the first cold molten salt pump 1A in Example 3;

[0065] Close the eighth shut-off valve 10 and the ninth shut-off valve 11 of the absorber salt filling subsystem; close the fifth regulating valve 14, open the fourth shut-off valve 5, the fifth shut-off valve 6 and the fourth regulating valve 7, close the sixth shut-off valve 8, and open the seventh shut-off valve 9, thereby forming a flow circuit of the first cold molten salt pump 1A-the first check valve 2A-the first cold molten salt pump outlet branch pipe 61A-the first shut-off valve 3A-the cold molten salt pump outlet main pipe 62-the first flow meter 21-the fourth shut-off valve 5-the fifth shut-off valve 6-the fourth regulating valve 7-the seventh shut-off valve 9-the cold molten salt tank 31, thereby realizing the single-unit debugging of the first cold molten salt pump 1A.

[0066] Similarly, the second cold molten salt pump 1B and the third cold molten salt pump 1C can be debugged separately.

[0067] Embodiment 5:

[0068] This embodiment provides a method for operating a molten salt heat collection system of a tower-type CSP power station, using the molten salt heat collection system of a tower-type CSP power station described in Example 1, the method in Example 2, the method in Example 3 and / or the method in Example 4, to realize salt charging of a heat absorber. Before the heat absorber 33 is started, salt charging of the heat absorber is carried out, and the salt charging of the heat absorber is carried out according to the following contents:

[0069] Filling the downcomer with salt: starting at least one cold molten salt pump, for example, the first cold molten salt pump 1A;

[0070] Open the pump outlet shut-off valve corresponding to the cold molten salt pump on the same side, for example, the first shut-off valve 3A corresponding to the first cold molten salt pump 1A, and open the fourth shut-off valve 5; close the eighth shut-off valve 10, the ninth shut-off valve 11, the fifth regulating valve 14, the fifth shut-off valve 6 and the fourth regulating valve 7, and the molten salt at the outlet of the cold molten salt pump enters the downcomer salt filling subsystem;

[0071] After the downcomer salt filling subsystem is filled with molten salt, since the fifth shut-off valve 6 and the fourth regulating valve 7 are in a closed state, as the pump continues to operate, the molten salt flows upward along the downcomer 71 into the outlet buffer tank 34. When the liquid level in the outlet buffer tank 34 reaches the first set value, the downcomer salt filling process is completed.

[0072] Embodiment 6:

[0073] This embodiment provides a method for operating a molten salt heat collection system of a tower-type CSP power station, using the molten salt heat collection system of a tower-type CSP power station described in Example 1, the method in Example 2, the method in Example 3, the method in Example 4 and / or the method in Example 5, to realize salt filling of a heat absorber. Before the heat absorber 33 is started, salt filling of the heat absorber is carried out, and the salt filling work of the heat absorber is carried out according to the following contents:

[0074] Salt filling of the absorber: after the liquid level of the outlet buffer tank 34 reaches the first set value, the ninth shut-off valve 11, the tenth shut-off valve 12 and the eleventh shut-off valve 13 are opened, and the molten salt flows upward along the absorber salt filling pipeline 92 into the absorber 33, and then enters the outlet buffer tank through the absorber venting pipeline 93;

[0075] When the liquid level of the outlet buffer tank 34 reaches the second set value, the salt filling process of the heat absorber is completed.

[0076] Embodiment 7:

[0077] The present embodiment provides a method for operating a molten salt collector system of a tower-type solar thermal power station, using the molten salt collector system of a tower-type solar thermal power station as described in Example 1, the method in Example 2, the method in Example 3, the method in Example 4, the method in Example 5 and / or the method in Example 6, to realize the operation of the salt filling and downcomer subsystem of the absorber 33, and carry out the startup process of the absorber 33 according to the following content.

[0078] Complete the salt filling process of the heat absorber 33;

[0079] Close the fourth shut-off valve 5, the eighth shut-off valve 10, the ninth shut-off valve 11, the tenth shut-off valve 12 and the eleventh shut-off valve 13, open the fifth regulating valve 14, and apply salt to the heat absorber 33 through the heat absorber riser pipe system.

[0080] Start the heliostat field and focus on the absorber tube panel, and the absorber 33 enters the heat absorption operation state;

[0081] When the molten salt temperature of the outlet buffer tank 34 is less than 400°C, it indicates that the heat absorber 33 is in the startup or low-load state. At this time, the sixth shut-off valve 8 is closed, the seventh shut-off valve 9 is opened, and the molten salt in the downcomer 71 enters the cold molten salt tank 31 through the downcomer bypass 72;

[0082] When the molten salt temperature of the outlet buffer tank 34 is greater than or equal to 400°C, it indicates that the heat absorber 33 has completed the startup process and is in normal operation. At this time, the sixth shut-off valve 8 is opened, the seventh shut-off valve 9 is closed, and the molten salt in the downcomer 71 enters the hot molten salt tank 32 through the downcomer main line 73.

[0083] Embodiment 8:

[0084] The present embodiment provides an operation method of a molten salt collector system of a tower-type CSP power station, which uses the molten salt collector system of a tower-type CSP power station described in Example 1, the method in Example 2, the method in Example 3, the method in Example 4, the method in Example 5, the method in Example 6 and / or the method in Example 7, realizes the parallel operation of multiple molten salt pumps, and starts the multiple molten salt pumps according to the increase in the load required by the heat absorber 33; when the first cold molten salt pump 1A is started, the second cold molten salt pump 1B and the third cold molten salt pump 1C are in a shutdown state, and the second cold molten salt pump 1B is started and paralleled according to the following contents, thereby increasing the inlet flow of the heat absorber 33, and then increasing the heat load of the heat absorber 33:

[0085] The first cold molten salt pump 1A is started according to the starting method of the first cold molten salt pump 1A in the above embodiment;

[0086] When the second cold molten salt pump 1B is turned on, the second regulating valve 4B corresponding to the pump on the same side is fully opened as the second cold molten salt pump 1B is started; at the same time, the second shut-off valve 3B is opened as the second cold molten salt pump 1B is started;

[0087] During the load increase process of the second cold molten salt pump 1B on the same side, the second regulating valve 4B is remotely operated according to the flow of the first flow meter 21, and its adjustment opening is gradually closed. When the flow of the second cold molten salt pump 1B on the same side (converted according to the flow measured by the first flow meter 21) reaches or exceeds a certain set value, the second regulating valve 4B is closed.

[0088] Embodiment 9:

[0089] This embodiment provides an operation method of a molten salt thermal collection system of a tower-type CSP power station, using the molten salt thermal collection system of a tower-type CSP power station described in Example 1, the method in Example 2, the method in Example 3, the method in Example 4, the method in Example 5, the method in Example 6, the method in Example 7 and / or the method in Example 8, to achieve salt release in the molten salt thermal collection system:

[0090] The heliostat field is defocused, and the absorber 33 is adjusted from the heat absorbing operation state to the non-heat absorbing operation state, and the molten salt in the outlet buffer tank 34 enters the hot molten salt tank 32 through the downcomer system;

[0091] The ninth shut-off valve 11 is opened, and the molten salt in the heat absorber 33 enters the hot molten salt tank 32 through the downcomer system;

[0092] During the shutdown process of the last running cold molten salt pump, when the forward flow measured by the first flow meter 21 drops to a certain set value, the regulating valve on the minimum flow recirculation branch corresponding to the molten salt pump on this side is opened, so that when the last running molten salt pump is shut down, the molten salt in the heat absorber riser system flows back into the cold molten salt tank 31 through the cold molten salt pump outlet mother pipe 62. Among them, the forward flow refers to the flow from the cold molten salt pump to the heat absorber 33.

[0093] Since the pipeline equipment combination of the molten salt solar collector system can be deeply coupled with its layout type and used in conjunction with it, the salt discharged from the entire molten salt solar collector system can be directly discharged into the cold molten salt tank or the hot molten salt tank by gravity.

[0094] Embodiment 10:

[0095] The present embodiment provides a method for operating a molten salt thermal collection system of a tower-type solar thermal power station, using the molten salt thermal collection system of a tower-type solar thermal power station as described in Example 1, the method in Example 2, the method in Example 3, the method in Example 4, the method in Example 5, the method in Example 6, the method in Example 7, the method in Example 8 and / or the method in Example 9.

[0096] like Figure 4 and Figure 5 As shown, a vacuum breaking hole is provided on the pipe section where the minimum flow recirculation main pipe of the pump is inserted into the cold molten salt tank, above the highest liquid level of the storage tank and below the top of the storage tank. When the last running cold molten salt pump is shut down, the air in the tank enters the minimum flow recirculation main pipe of the pump through the vacuum breaking hole, and enters the pump outlet branch pipe through the minimum flow recirculation regulating valve of the pump that has been interlocked and opened with the shutdown of the cold molten salt pump and the forward flow of the flow measured by the first flow meter 21 ≤ the first set value, thereby destroying the vacuum behind the check valve caused by the sudden stop of the pump, avoiding the gasification of molten salt caused by the sudden pressure drop and the resulting gas-liquid two-phase flow impact, salt hammer hitting the valve, pipeline vibration, sudden increase in structural load and other problems.

[0097] In summary, the system of the present invention only needs to set a flow meter on the outlet main pipe of the cold molten salt pump, and does not need to set a flow meter on each outlet branch pipe of the cold molten salt pump, thereby saving expensive flow meter investment; the regulating valve of the minimum flow recirculation branch of the cold molten salt pump is the valve with the lowest arrangement height, and the regulating valve of the minimum flow recirculation branch also serves as the salt discharge valve of the entire pipeline system, that is, the minimum flow recirculation branch of the cold molten salt pump also has the function of the salt discharge pipeline, thereby saving the investment in the salt discharge valve and reducing the risk of molten salt freezing and blockage; the vent valve at the outlet of the heat absorber is the valve with the highest arrangement height, therefore, the vent valve at the outlet of the heat absorber also serves as the vent valve of the entire pipeline system, That is to say, the vent valve at the outlet of the heat absorber also has the function of venting the entire pipeline system; when a molten salt pump stops running, the interlock opens the regulating valve of the minimum flow recirculation branch of the pump corresponding to the cold molten salt pump on the same side. On the one hand, at the moment when the regulating valve of the minimum flow recirculation branch of the cold molten salt pump is opened, the gas in the cold molten salt storage tank enters the outlet branch of the cold molten salt pump through the vacuum breaking hole, which plays a role in destroying the vacuum. On the other hand, after the regulating valve of the minimum flow recirculation branch of the cold molten salt pump is opened, a leakage channel leading to the cold molten salt tank through the outlet branch of the cold molten salt pump and the minimum flow recirculation branch of the cold molten salt pump is formed. The above two aspects can prevent the generation of molten salt gas-liquid two-phase flow, thereby effectively reducing the pipeline vibration caused by salt hammer. All the discharged salt in the outlet pipeline system of the cold molten salt pump can be directly discharged to the cold molten salt tank, so there is no need to set up a separate salt discharge tank, salt discharge pump and related salt discharge pipelines, salt discharge related equipment and pipeline electric heating in the storage tank area, which saves both investment and operation and maintenance costs.

[0098] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. The tower-type solar thermal power station molten salt collector system is characterized by: It includes a cold molten salt tank, a cold molten salt pump connected to the cold molten salt tank, a cold molten salt pump outlet branch connected to the cold molten salt pump, a cold molten salt pump outlet main pipe connected to the cold molten salt pump outlet branch pipe, a riser connected to the cold molten salt pump outlet main pipe, a heat absorber connected to the riser, and an outlet buffer tank connected to the heat absorber at least through a heat absorber venting pipe; A shut-off valve is provided on the absorber venting pipeline, and the cold molten salt pump outlet branch pipe, the cold molten salt pump outlet main pipe, the riser, the absorber and the absorber venting pipeline are sequentially connected from the cold molten salt tank to the outlet buffer tank, and are arranged in a gradually increasing height.

2. The tower-type solar thermal power station molten salt heat collection system according to claim 1, characterized in that: The outlet branch of the cold molten salt pump is connected to the minimum flow recirculation branch through a tee; a regulating valve is provided on the minimum flow recirculation branch, and the minimum flow recirculation branch is connected to the cold molten salt tank; the minimum flow recirculation branch from the tee to the cold molten salt tank and then to the cold molten salt tank are connected in sequence, and a layout with a gradually decreasing height is adopted.

3. The tower-type solar thermal power station molten salt heat collection system according to claim 2, characterized in that: The minimum flow recirculation branch pipe is connected to the cold molten salt tank through the minimum flow recirculation main pipe; a vacuum breaking hole is provided on the pipe section of the minimum flow recirculation main pipe inserted into the cold molten salt tank; the vacuum breaking hole is located below the tank top of the cold molten salt tank and above the highest liquid level of the cold molten salt tank.

4. The tower-type solar thermal power station molten salt heat collection system according to claim 2, characterized in that: On the outlet branch of the cold molten salt pump, a check valve and a shut-off valve are arranged in sequence along the outlet flow direction of the pump; the tee connecting the outlet branch of the cold molten salt pump and the minimum flow recirculation branch is located between the check valve and the shut-off valve on the outlet branch of the cold molten salt pump.

5. The tower-type solar thermal power station molten salt heat collection system according to claim 1, characterized in that: The cold molten salt tank is connected to a plurality of cold molten salt pumps, each of the cold molten salt pumps is respectively connected to a cold molten salt pump outlet branch pipe, and the plurality of cold molten salt pump outlet branch pipes are commonly connected to a cold molten salt pump outlet main pipe.

6. The tower-type solar thermal power station molten salt heat collection system according to claim 5, characterized in that: The outlet main pipe of the cold molten salt pump is provided with a first flow meter; the outlet main pipe of the cold molten salt pump is connected with a riser, and a regulating valve and a second flow meter are provided on the pipeline between the riser and the heat absorber.

7. The tower-type solar thermal power station molten salt heat collection system according to claim 6, characterized in that: The outlet buffer tank is connected to the downcomer, and the downcomer is provided with relevant shut-off valves and regulating valves; the downcomer is connected to the hot molten salt tank through a downcomer main line, and the downcomer main line is provided with relevant shut-off valves; the downcomer is connected to the cold molten salt tank through a downcomer bypass, and the downcomer bypass is provided with relevant shut-off valves.

8. The tower-type solar thermal power station molten salt heat collection system according to claim 7, characterized in that: A downcomer salt filling main pipe is arranged between the cold molten salt pump outlet main pipe and the downcomer, and a shut-off valve is arranged on the downcomer salt filling main pipe.

9. The tower-type solar thermal power station molten salt heat collection system according to claim 7, characterized in that: A heat absorber salt filling mother pipe is arranged between the ascending pipe and the descending pipe, and a relevant shut-off valve is arranged on the heat absorber salt filling mother pipe; the heat absorber salt filling mother pipe is connected to the heat absorber through a heat absorber salt filling and salt supplying pipeline, and a relevant shut-off valve is arranged on the heat absorber salt filling and salt supplying pipeline.

10. Operation method of molten salt heat collection system of tower type solar thermal power station, characterized in that: The tower-type solar thermal power station molten salt collector system as described in any one of claims 1 to 9 is used, comprising: the shut-off valve on the absorber vent pipe also serves as the vent valve of the entire system.

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