WO2022267152A1

WO2022267152A1 - Salt melting system for solar thermal power station based on molten salt solar heat collection field

Info

Publication number: WO2022267152A1
Application number: PCT/CN2021/108067
Authority: WO
Inventors: 栾海峰
Original assignee: 北京蓝海翌能新能源集团有限公司
Priority date: 2021-06-23
Filing date: 2021-07-23
Publication date: 2022-12-29
Also published as: ES2960658A1; CN113304694A

Abstract

A salt melting system for a solar thermal power station based on a molten salt solar heat collection field (2), the system comprising a salt melting furnace (1), the molten salt solar heat collection field (2), and a molten salt storage tank (3), wherein the salt melting furnace (1) is in communication with an inlet of the molten salt solar heat collection field (2) by means of a molten salt pipeline (4); the salt melting furnace (1) is in communication with the molten salt storage tank (3) by means of a conveying pump (5); and an outlet of the molten salt solar heat collection field (2) is in communication with the salt melting furnace (1) by means of a first pipeline (11).

Description

A Salt Chemical System of Solar Photothermal Power Station Based on Molten Salt Solar Collector Field

technical field

The invention relates to a molten salt melting salt system of a solar photothermal power station, which belongs to the technical field of salt melting systems.

Background technique

Before the molten salt is put into the solar thermal power station, it is mainly supplied in solid form (because molten salt is solid at room temperature), and the supply in solid form is convenient for the transportation and storage of molten salt. And when the molten salt needs to be put into the solar thermal power station for heat storage, it is necessary to convert a large amount of solid molten salt into high temperature liquid molten salt. A key procedure before the system enters commissioning and operation. The molten salt changes from solid to liquid through this process. The high-temperature molten salt enters the system and starts to circulate, and remains liquid throughout the life of the power station.

In the existing photothermal solar photothermal power station, there are roughly two schemes to realize the salt transformation. One is to use the electric heater to initialize the salt, and then use the molten salt circulation pump to pump the low-temperature liquid molten salt into the natural gas salt furnace In the process, the molten salt in the coil in the molten salt furnace is heated to a high temperature state by the high-temperature flue gas generated by burning natural gas, and then transported back to the molten salt tank. Sodium nitrate and potassium nitrate (solid molten salt) are added to the molten salt tank in proportion. When the temperature of the molten salt in the molten salt tank meets the requirements, the molten salt is transported to the molten salt tank through another molten salt delivery pump; The second is that sodium nitrate and potassium nitrate are pulverized and mixed in proportion, and then directly enter the natural gas salt furnace. A heat exchange coil is installed in the furnace, and the pipe contains high-temperature flue gas. Its flow direction is opposite to that of the liquid in the furnace. The molten salt overflows into the buffer tank through the overflow pipe, and then pumps from the buffer tank into the molten salt tank. Both of the above two traditional salt melting methods use the flue gas after natural gas combustion as the heat source for heating solid molten salt particles, and a large amount of natural gas is consumed in the salt melting process. Due to the technical limitations of the natural gas furnace itself and for safety reasons, the salt melting speed is about 30-40 t/h. After the desalination is completed, the supporting desalination equipment has no use value in this project and can only be used for the next project to desalt again or put aside for waste.

In addition to the above statements, the conventional way of salting also has the following disadvantages:

1. The cost of the built-up salt melting furnace system using natural gas heating to realize salt melting is high, and after the salt melting is realized once, the molten salt is put into the solar thermal system for use, and there is no need to melt salt again, so The supporting natural gas salt furnace system equipment cannot be used reasonably;

2. When using the natural gas salt furnace system to realize salt conversion, natural gas needs to be burned. In the molten salt project of a large-scale solar thermal power station with tens of thousands of tons, the cost of natural gas consumed is relatively high;

3. The use of natural gas salt furnace system to burn natural gas emits a large amount of carbon dioxide, which has certain pollution to the environment;

4. The heating capacity of the natural gas salt furnace system is limited. In the molten salt project of a large-scale solar thermal power station with tens of thousands of tons, the salt melting speed is relatively slow and the salt melting cycle is long.

Based on the above situation, it is of great significance to carry out the research on the technical solution of salt to shorten the cycle of salt, to reduce the cost of salt, to improve the speed and quality of salt, and to ensure the balance between solar thermal power generation and salt.

technical problem

The present invention aims at shortening the period of desalting and reducing the cost of desalting. A brief overview of the invention is given below in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical parts of the invention nor to delineate the scope of the invention.

technical solution

A salt chemical system of a solar photothermal power station based on a molten salt solar heat collection field, including a salt furnace, a molten salt solar heat collection field and a molten salt storage tank, and the salt furnace is connected to a molten salt solar heat collection through a molten salt pipeline The salt furnace communicates with the molten salt storage tank through a delivery pump, and the outlet of the molten salt solar heat collection field communicates with the salt furnace through the first pipeline.

Preferably: an auxiliary electric heater is also included, the inlet of the auxiliary electric heater communicates with the molten salt pipeline, and the auxiliary electric heater communicates with the salt furnace through the second pipeline.

Preferably: valves and temperature measuring instruments are respectively installed on the first pipeline and the second pipeline.

Preferably: the electric energy used in the auxiliary electric heater comes from abandoned wind power, abandoned photovoltaic power or low valley power.

Preferably: a circulation pump is installed on the connection pipeline between the salt furnace, the molten salt solar heat collection field and the auxiliary electric heater.

Beneficial effect

1. The salt melting system of the present invention solves the problem that the solid molten salt of conventional photothermal power plants is melted through the special natural gas salt melting furnace system, while the conventional special natural gas salt melting furnace realizes the salt melting process. The consumption and other factors are limited, the salt conversion efficiency is not high, the entire salt conversion cycle cannot be guaranteed, and the cost of salt conversion fuel is high.

2. The present invention utilizes the photothermal power generation system to carry out the salt conversion work, so that both power generation and salt conversion are correct, and the salt conversion capacity is much greater than that of the dedicated natural gas salt conversion furnace system;

3. In the present invention, when there is sun in the daytime, salt is converted by light and heat, and when there is no sun at night, electric heating is used to absorb abandoned electricity or low-peak electricity to convert salt, which effectively shortens the cycle of salt conversion.

4. Compared with the conventional way of salt melting, the present invention realizes salt melting through photothermal method, and its speed of salt melting is significantly improved, and the system is simple, easy to operate, high in safety, energy-saving and environment-friendly.

5. Compared with the conventional salt conversion method, the present invention is affected by the equipment environment, the equipment itself, and the plant environment, and the cleanliness of the salt is low, while the salt conversion is performed by the light-heat heat exchange method, which is clean and efficient.

6. Using the salt solution solution of the present invention, the sodium nitrate and potassium nitrate are crushed and transported to the salt furnace in proportion. After initializing the salt with an electric heater, the low-temperature liquid in the salt furnace is melted The salt is pumped into the molten salt solar heat collection field, and the high temperature of solar energy is absorbed by the molten salt solar heat collection field, the molten salt is heated to a high temperature state, and then transported back to the salt furnace, and the high temperature liquid salt is mixed with the normal temperature solid molten salt to form 270 The low-temperature liquid molten salt above ℃ is transported and stored in the molten salt storage tank.

The salt melting speed of the photothermal salt system exceeds 210 t/h, which is 5-7 times faster than the traditional salt melting speed. Photothermal salt uses solar energy as the heat source for salt melting, without any fossil fuels, and is clean and environmentally friendly. Due to the use of the original heat exchange equipment of the photothermal power station, the construction cost is saved. After the salt is completed, the supporting feeding system can be disassembled and recycled for reuse, and the salt furnace and electric heater can be directly converted into a high-temperature energy storage system, which is used to absorb abandoned wind and light, and realize energy storage.

7. Using the salt melting system of the present invention, the salt melting speed exceeds 210 tons per hour, which is five times faster than the traditional salt melting speed, and can exceed 4,000 tons per day, which is more than four times the previous single-day salt melting world record. It only takes two and a half weeks to melt 70,000 tons of salt, which is two months faster than the traditional way of salt melting. The energy storage system can generate electricity in advance, saving tens of millions of fossil fuels for salt melting, and saving 20% in equipment investment compared with traditional salt melting systems. .

Description of drawings

Fig. 1 is a salt system diagram of a solar thermal power station based on a molten salt solar collector field;

Fig. 2 is the diagram of the chemical salt system of the second embodiment;

Fig. 3 is a schematic diagram of the relationship between the amount of salt and the period of salt in the traditional way of salt and the way of salt in the present invention;

In the figure, 1- chemical salt furnace, 2- molten salt solar thermal field, 3- molten salt storage tank, 4- molten salt pipeline, 5- delivery pump, 8- valve, 9- temperature measuring instrument, 10- auxiliary electric Heater, 11-first pipeline, 12-second pipeline, 14-circulation pump.

Embodiments of the present invention

In order to make the object, technical solution and advantages of the present invention clearer, the present invention is described below through specific embodiments shown in the accompanying drawings. It should be understood, however, that these descriptions are exemplary only and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

Specific implementation mode one:

Referring to Fig. 1, the present embodiment provides a salt chemical system of a solar thermal power station based on a molten salt solar heat collecting field, including a chemical salt furnace 1, a molten salt solar heat collecting field 2 and a molten salt storage tank 3. The chemical salt furnace 1 is connected to the entrance of the molten salt solar heat collection field 2 through the molten salt pipeline 4, the chemical salt furnace 1 is connected to the molten salt storage tank 3 through the delivery pump 5, and the outlet of the molten salt solar heat collection field 2 is passed through the first pipeline 11 It is connected with the salt furnace 1.

In this embodiment, in the salt furnace 1, solid salt and 300-440 degree high temperature molten salt are mixed in the salt furnace 1 to form a 280-340 degree medium temperature liquid molten salt, and the formed medium temperature liquid molten salt is It is sent to the molten salt storage tank 3 through the delivery pump 5 for storage, and the other part is pumped into the molten salt solar heat collection field 2 through the circulation pump, and the medium-temperature liquid molten salt (280-340°C) is heated and transformed through the molten salt solar heat collection field 2 It is a high-temperature liquid molten salt (300-440°C). Subsequently, the high-temperature molten salt is transported to the salt furnace 1 to realize the circulation of salt. The amount of delivery ensures that the solid molten salt newly added to the salt furnace 1 can reach a certain level temperature, and melt the solid molten salt.

In this embodiment, the molten salt solar heat collection field 2 is used to increase the temperature of the medium-temperature molten salt to the high-temperature molten salt, and the temperature of the high-temperature molten salt is used to realize the work of converting salt, realizing both power generation and converting salt, and converting salt The capacity is much larger than that of the salt furnace system;

In this embodiment, the molten salt solar heat collection field 2 includes molten salt tank type, tower type heat collectors and the like.

The salt conversion system in this embodiment solves the problem that the solid molten salt of conventional photothermal power plants is converted into salt through a dedicated natural gas salt conversion furnace system, while the conventional dedicated natural gas salt conversion furnace realizes the salt conversion process. Due to the limitation of factors such as the amount of natural gas used, the entire salt chemical cycle cannot be guaranteed, and the cost of salt chemical remains high.

In this embodiment, using the salt chemical system of this embodiment, the salt chemical speed exceeds 210 tons per hour, which is five times faster than the traditional salt chemical process, and can exceed 4,000 tons per day, which is four times the previous single-day salt chemical world record As mentioned above, if it only takes two and a half weeks to melt 70,000 tons of salt continuously, which is two months faster than the traditional way of salt melting, it can realize heat storage island power generation in advance, save tens of millions of fossil fuels for salt melting, and the investment in equipment is also higher than that of traditional salt melting The system saves 20%, the specific comparison is shown in the figure:

Table 1. Comparison of photothermal salt system and traditional salt system

It should be noted that in solar power generation projects, the current international conventional salt system uses natural gas salt furnace, which uses the flue gas after natural gas combustion to provide heat to melt solid molten salt into a liquid state.

When a solar power generation project needs salt, the conventional way is to buy a natural gas salt furnace, and then use the flue gas after natural gas combustion to provide heat to melt the solid molten salt into a liquid state;

Different from the conventional way of salt melting, in this embodiment, the original equipment of the solar power plant is used for the salt melting operation, for example, the molten salt solar collector field 2 used in this embodiment is the existing equipment of the power plant , the original function of this equipment is to be used for solar power generation, in this embodiment, according to the cooperation and connection mode of each technical feature in this embodiment, it is composed of a salt system, and the system is used to realize the salt, so That is to say, it saves the cost of purchasing and building a natural gas salt furnace, reduces the carbon dioxide emission in the salt process, and improves the speed and cycle of salt by using existing equipment (as shown in Figure 3);

It should be noted that the heat storage medium used in the solar-thermal power station project is high-temperature molten salt. Taking the 100 MW trough-type heat-conducting oil solar-thermal power generation project in Wulate Zhongqi as an example, the power station is equipped with a high-temperature molten salt heat storage system. The high-temperature molten salt used in the system is a mixture of 40% potassium nitrate and 60% sodium nitrate by mass fraction. Before the molten salt energy storage system is put into operation, the solid molten salt must be melted and injected into the cold salt tank. This step (saltification) plays a vital role in the smooth commissioning and official commissioning of the heat storage system. At present, the conventional salt melting systems in the world all use natural gas salt melting furnaces, which use the flue gas after natural gas combustion to provide heat to melt the solid molten salt into a liquid state. This conventional salt conversion system not only has a low rate of salt conversion and cannot put the heat storage system into normal operation in a short period of time, but also consumes a large amount of fossil fuels, which is contrary to the "double carbon" commitment. However, limited by the high melting temperature of molten salt and many technical difficulties in the salt melting system, practical exploration of high-speed, low-carbon new salt melting technology at home and abroad is almost zero.

The use of the salt chemical system of this embodiment can ensure both solar thermal power generation and salt chemical conversion, and it is of great significance to realize salt chemical conversion in a solar thermal power generation project.

Specific implementation mode two:

As shown in FIG. 2 , a solar thermal power plant salt system based on a molten salt solar heat collection field includes a salt furnace 1, a molten salt solar heat collection field 2 and a molten salt storage tank 3. The salt furnace 1 The entrance of the molten salt solar heat collection field 2 is connected through the molten salt pipeline 4, the salt furnace 1 is communicated with the molten salt storage tank 3 through the delivery pump 5, and the outlet of the molten salt solar heat collection field 2 is connected with the salt furnace through the first pipeline 11 1, and also includes an auxiliary electric heater 10, the inlet of the auxiliary electric heater 10 communicates with the molten salt pipeline 4, and the auxiliary electric heater 10 communicates with the salt furnace 1 through the second pipeline 12.

In this embodiment, in the salt furnace 1, solid salt and 300-440 degree high temperature molten salt are mixed in the salt furnace 1 to form a 280-340 degree medium temperature liquid molten salt, and the formed medium temperature liquid molten salt is Send it to the molten salt storage tank 3 for storage through the delivery pump 5, and the other part is driven into the molten salt solar heat collection field 2 and/or the auxiliary electric heater 10 through the circulation pump, and passes through the molten salt solar heat collection field 2 or auxiliary electric heating The device 10 heats the medium-temperature liquid molten salt (280-340°C) into a high-temperature liquid molten salt (300-440°C), and then transports the high-temperature molten salt to the salt furnace 1 to realize the circulation of salt. Ensure that the solid molten salt newly added into the salt furnace 1 can reach a certain temperature and melt the solid molten salt.

Specific implementation mode three:

With reference to Fig. 1, shown in Fig. 2, and on the basis of specific embodiment one and specific embodiment two, valve 8 and temperature measuring instrument 9 are respectively installed on described first pipeline 11 and second pipeline 12, valve 8 uses To control the switch of the pipeline, the temperature measuring instrument 8 is used to measure the temperature of the fluid in the pipeline. The opening and closing of the molten salt in the first pipeline 11 and the second pipeline 12 is monitored in real time by using the information interaction between the valve 8 and the temperature measuring instrument 9, so as to ensure the smooth progress of the salt melting work.

Specific implementation mode four:

On the basis of Embodiment 2, the electric energy used in the auxiliary electric heater 10 comes from low-cost electricity such as abandoned wind power, abandoned photovoltaic power, and low-peak electricity. The cost of this electric energy is lower than the cost of electric energy provided by conventional power stations.

Specific implementation mode five:

Referring to Fig. 1 and Fig. 2, and in conjunction with the specific embodiment 1, a circulation pump 14 is installed on the connection pipeline between the salt furnace 1, the molten salt solar heat collection field 13 and the auxiliary electric heater 10. The circulation pump 14 is used to pump the low-temperature liquid molten salt in the chemical salt furnace into the molten salt solar heat collection field.

It should be noted that the terminology used here is only used to describe specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

The relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. At the same time, it should be understood that, for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the Authorized Specification. In all examples shown and discussed herein, any specific values should be construed as illustrative only, and not as limiting. Therefore, other examples of the exemplary embodiment may have different values. It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

In the description of the present invention, it should be understood that orientation words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" etc. indicate the orientation Or positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description. In the absence of a contrary description, these orientation words do not indicate or imply the device or element referred to. It must have a specific orientation or be constructed and operated in a specific orientation, so it should not be construed as limiting the protection scope of the present invention; the orientation words "inner and outer" refer to the inner and outer relative to the outline of each component itself.

For the convenience of description, spatially relative terms may be used here, such as "on ...", "over ...", "on the surface of ...", "above", etc., to describe the The spatial positional relationship between one device or feature shown and other devices or features. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, devices described as "above" or "above" other devices or configurations would then be oriented "beneath" or "above" the other devices or configurations. under other devices or configurations". Thus, the exemplary term "above" can encompass both an orientation of "above" and "beneath". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

It should be noted that the terms "first" and "second" in the description and claims of the present application and the above drawings are used to distinguish similar objects, but not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein.

It should be noted that, in the above embodiments, as long as the technical solutions that do not contradict each other can be permutated and combined, those skilled in the art can exhaust all possibilities according to the mathematical knowledge of permutations and combinations, so the present invention is no longer concerned with the technical solutions after permutations and combinations. Each will be described, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

This embodiment is only an exemplary description of this patent, and does not limit its protection scope. Those skilled in the art can also make partial changes to it, as long as it does not exceed the spirit and essence of this patent, all within the protection scope of this patent.

Claims

A solar thermal power plant salt system based on a molten salt solar heat collection field, characterized in that it includes a salt furnace (1), a molten salt solar heat collection field (2) and a molten salt storage tank (3), the The salt furnace (1) is connected to the entrance of the molten salt solar heat collection field (2) through the molten salt pipeline (4), and the salt furnace (1) is connected to the molten salt storage tank (3) through the delivery pump (5), and the molten salt The outlet of the solar heat collecting field (2) communicates with the salt furnace (1) through the first pipeline (11).
According to claim 1, a solar thermal power plant salt system based on molten salt solar heat collection field is characterized in that: it also includes an auxiliary electric heater (10), and the entrance of the auxiliary electric heater (10) is connected with the lava The pipeline 4 communicates, and the auxiliary electric heater (10) communicates with the chemical salt furnace (1) through the second pipeline (12).
Type in claim item 3 here. According to claim 2, a solar thermal power station salt system based on molten salt solar thermal field, characterized in that: the first pipeline (11) and the second pipeline ( 12) are respectively equipped with a valve (8) and a temperature measuring instrument (9).
According to claim 2, a solar thermal power plant salt system based on a molten salt solar heat collection field is characterized in that: the electric energy used in the auxiliary electric heater (10) comes from abandoned wind power, abandoned photovoltaic power or Low power.
According to claim 2, a solar thermal power station chemical salt system based on a molten salt solar heat collection field is characterized in that: the salt furnace (1) is connected with the molten salt solar heat collection field (13) and the auxiliary electricity A circulating pump (14) is installed on the connecting pipeline of the heater (10).