CN103148602A - Solid particle accumulation bed-type air heat absorber for solar thermal power station - Google Patents

Abstract

A solid particle stacked bed air heat absorber for a solar thermal power station, consisting of quartz glass tube bundles (1), solid particles (2), cold air headers (3), hot air headers (4), and cold air inlets (5) and hot air outlet (6). The quartz glass tube bundle (1) is composed of multiple quartz glass tubes. Solid particles (2) are accumulated inside the quartz glass tubes in the quartz glass tube bundle (1), and the solid particles (2) remain static during the working process. The cold air header (3) is located at the lower part of the quartz glass tube bundle (1) and is sealed and connected with the lower part of the quartz glass tube bundle (1), and the hot air header (4) is located at the upper part of the quartz glass tube bundle (1) and is connected with the quartz glass tube bundle (1) ) of the upper seal connection. The cold air inlet (5) is located on the cold air header (3), and the hot air outlet (6) is located on the hot air header (4). The present invention can obtain high-temperature air of 700°C-1300°C, normal pressure or pressure above 1MPa, and utilize its own sensible heat storage at the same time.

Description

Solid Particle Packed Bed Air Heater for Solar Thermal Power Station

technical field

The invention relates to an air heat absorber for a solar thermal power station.

Background technique

Solar energy is an inexhaustible renewable energy source. Today, as fossil fuels are decreasing year by year and the international energy situation is becoming increasingly severe, the development and utilization of solar energy is one of the important ways to realize the diversification of energy supply and ensure energy security. The basic principle of the tower thermal power generation device is to use many heliostats to reflect solar radiation to the solar receiver placed on the tower, and generate superheated steam or high-temperature air with the help of heating medium to drive the generator set to generate electricity. The high temperature solar heat absorber is the core component of the tower thermal power generation system. Many studies on this technology have been carried out abroad, mainly in the United States, Spain, Germany, Israel, Australia, South Korea and so on. Among them, the most widely used is the volumetric heat absorber, which is a heat absorber composed of a three-dimensional matrix to receive solar radiation, and the working fluid flowing through it is heated by direct heat exchange with it. The volumetric solar heat absorber usually has a hollow shell for containing the volumetric solar absorbing device, and the shell is covered by a glass light-transmitting window to form a closed heat absorbing device cavity, which can accommodate the direct contact with the absorbing device. Working fluid, the working fluid flows through the cavity of the heat absorbing device and absorbs heat from the absorbing device. U.S. Patent 4394859 discloses a cylindrical metal tube heat absorber with air as the heat transfer fluid. temperature of the air. US Patent No. 4,777,934 discloses a solar heat absorber that uses compressed air with particles as a heat transfer fluid, and its temperature can be heated to 700° C., but the heat absorber cannot be applied to higher temperatures. U.S. Patent US6668555B1 discloses a solar power generation system based on a heat absorber. A heat pipe solar heat absorber is used. The heat transfer medium is air. Although the heat transfer efficiency is high, it is necessary to use metal sodium and other substances as the heat pipe for high temperature applications. phase change materials, which have strict requirements on safety. Chinese patent CN2758657 proposes a cavity-type solar absorber, which is divided into two cavities inside and outside. The inner cavity is coated with a solar selective absorption coating near the surface of the quartz glass window, and different materials are used for heat transfer and heat storage. High temperature occasions, but its structure is more complex. Chinese patent CN2872208 proposes a cavity-type solar air heat absorber, which uses a needle tube to cool the glass window and a tubular heat absorber. The heat transfer surface area of the tubular heat absorber is small, the heat transfer efficiency is not high, and the cooling glass window is also difficult to manufacture. for larger sizes.

To sum up, in order to obtain high-temperature and high-pressure air, the current air heat sinks mostly use quartz glass windows to achieve light transmission and sealing functions. Due to the limitation of the production process of quartz glass, it is difficult to process a single piece of quartz glass into a larger area. , limiting the power of the pressurized air heater. In the usual volumetric air heat absorber, there will be local "hot spots" on the ceramic or metal heat absorber, which will cause damage to the heat absorber, and in high-power applications, there are problems in the preparation and connection of large-scale ceramic bodies. technical challenge.

Contents of the invention

The purpose of the present invention is to overcome the disadvantage that the existing pressurized air heat absorber is difficult to be used for larger power, and provide a new air heat absorber.

In the present invention, the quartz glass tube of the quartz glass tube bundle is used as the air flow channel, the high light transmittance and high temperature resistance characteristics of the quartz glass are used, and the solid particles in the stacked quartz glass tube are used as the heat absorber, and the high absorption rate of the solid particles and the high temperature resistance are used. High temperature, high thermal conductivity, and large specific surface area for efficient heat absorption and heat transfer.

The solid particles also have a heat storage function when receiving solar radiation, which can avoid large fluctuations in air temperature within a certain period of time. The present invention can build larger-capacity air heat absorbers according to usage requirements, and can be used in normal pressure and high pressure systems.

Selecting silicon carbide, silicon nitride, graphite and other high temperature-resistant materials as solid particles can be used in the temperature range of 1200 ° C and higher, which ensures that the air heat absorber of the present invention can be used at higher temperatures. The thermal conductivity of silicon carbide, graphite and other solid particles can be greater than 10W/(mK) at high temperature, and has a high radiation absorption rate. By designing the shape and size of the particles, the input solar radiation energy can be absorbed to the maximum. The solid particle group accumulated in the quartz glass tube has a large specific surface area, which ensures a high heat transfer efficiency between the air and the heat absorber during the heat exchange process.

The solid particle stacked bed type air heat absorber of the present invention uses the solid particles accumulated in the quartz glass tube as the heat absorbing medium, and the air as the heat transfer fluid. The heat absorber comprises an upper hot air header, a lower cold air header, and a quartz glass tube bundle sealingly connected with the hot air header and the cold air header. The quartz glass tube bundle is formed by arranging a plurality of quartz glass tubes with the same or different diameters. The quartz glass tube is filled with solid particles. One or more hot air outlets are opened on the side or bottom of the hot air header, and one or more cold air inlets are opened on the side or bottom of the cold air header. The solid particles are spherical, ellipsoid or other shapes, and the particle size can be the same or different. The parameters such as the shape, particle diameter and particle density of the solid particles are determined by the velocity distribution of the air flowing into the quartz glass tube bundle. The principle is to realize the solid particles and air Fully heat exchange, the heat absorber works in a high temperature environment, and the part of the heat absorber that is not used to receive sunlight is covered with a high-temperature heat-resistant insulation layer to control heat loss.

The working process of the present invention is as follows:

The concentrated radiant energy flow collected by the concentrating equipment is projected onto the surface of the quartz glass tubes that form the quartz glass tube bundle, part of the radiant energy is reflected by the surface of the quartz glass tube facing the radiation energy input side, part of the radiant energy flow is absorbed by the quartz glass tube, and part of the radiant energy is absorbed by the quartz glass tube. The radiant energy flow is reflected and absorbed by the solid particles filled in the quartz glass tube. There are gaps between the solid particles, and the radiant energy flow propagates in the gaps. The convective heat transfer between the cold air and the surface of the solid particles with higher temperature, because there are gaps between the solid particles, the heat transfer area between the air and the solid particles is larger, and the heat transfer efficiency is higher. The solid particle diameter is selected between 0.1-10mm, and a suitable particle diameter can realize efficient absorption of concentrated radiation energy flow and efficient heat transfer between air and solid particles.

The invention has a simple structure, and the size of the solid particles can be designed according to requirements, and the flow velocity of the air can be adjusted to realize the purposes of efficiently absorbing solar radiation energy and efficiently transferring heat to the air. The invention can obtain high-temperature air with a temperature range of 700°C-1600°C and normal pressure or pressure above 1MPa. At the same time, solid particles have the function of heat storage, which can control the fluctuation of air temperature output parameters within a certain time interval.

Description of drawings

Fig. 1 Working principle diagram of solid particle packed bed air heat absorber;

Figure 2 is a schematic diagram of the operation of a solar thermal power station using non-compressed air as a heat transfer fluid;

Figure 3 is a schematic diagram of the operation of a solar thermal power station in which compressed air is the heat transfer fluid;

In the figure: 1 quartz glass tube bundle, 2 solid particles, 3 cold air header, 4 hot air header, 5 cold air inlet, 6 hot air outlet, 7 concentrated radiation energy flow, 8 heliostat field, 9 support tower , 10 solid particle stacked bed air heat absorber, 11 cold air, 12 fan, 13 hot air, 14 steam generator, 15 water pump, 16 steam turbine, 17 generator, 18 water heat exchanger, 19 air compressor, 20 Cold compressed air, 21 hot compressed air, 22 air turbine.

Detailed ways

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

Fig. 1 shows the solid particle packed bed air heat absorber of the present invention. The heat absorber is composed of quartz glass tube bundle 1, solid particles 2, cold air header 3, hot air header 4, cold air inlet 5 and hot air outlet 6. The quartz glass tube bundle 1 is composed of a plurality of quartz glass tubes. The diameters of the quartz glass tubes can be the same or different, and the arrangement of the quartz glass tubes can be sequential or crossed. The arrangement form and quantity of the quartz glass tube bundles 1 are determined by the characteristics of the input concentrated radiation energy flow 7, and the principle is to ensure that all the concentrated radiation energy flows 7 put into the heat absorber are composed of solid particles 2 and composed of quartz glass The multiple quartz glass tubes of tube bundle 1 absorb. Solid particles 2 are filled in each quartz glass tube. The solid particles 2 have high radiation absorption rate and can be used for a long time at a temperature above 1600°C. The diameters of the solid particles 2 can be the same or different. The shape, particle diameter and particle size of the solid particles Parameters such as density are determined by the velocity distribution of the air flowing into the quartz glass tube bundle 1. The principle is to realize sufficient heat exchange between the solid particles 2 and the air. The material of the solid particles 2 can be silicon carbide ceramics, graphite, silicon nitride ceramics, etc. The cold air header 3 is located at the lower part of the quartz glass tube bundle 1 and is sealed and connected with the lower part of the quartz glass tube bundle 1 . The cold air header 3 can realize the collection of cold air and the distribution of air pressure and flow. The side or bottom of the cold air header 3 is provided with one or more cold air inlets 5. The position, size and quantity of the cold air inlets 5 are based on the cold air determined by the characteristics of the flow field. The hot air header 4 is located on the upper part of the quartz glass tube bundle 1 and is hermetically connected with the upper part of the quartz glass tube bundle 1 to realize hot air collection and air pressure distribution. One or more hot air headers are arranged on the side or top of the hot air header 4 The position, size and quantity of the outlet 6 and the hot air outlet 6 are determined according to the flow field characteristics of the hot air and solid particles 2 .

When working, the concentrated radiant energy flow 7 provided by the solar concentrating field is projected onto the quartz glass tube surface of the quartz glass tube bundle 1, and most of the radiant energy of the concentrated radiant energy flow 7 passes through the quartz glass tube wall to the quartz glass tube bundle On the solid particles 2 accumulated in 1, the solid particles 2 always maintain a static state during the working process. Because the solid particle 2 has a high radiation absorption rate, the concentrated radiation energy flow 7 is absorbed by the solid particle 2 and converted into heat energy of the solid particle 2, and a small part of the radiant energy is absorbed by the wall of the quartz glass tube and converted into heat energy of the quartz glass tube, which is absorbed by the solid particle 2. The temperature of the heated solid particles 2 and the quartz glass tube wall rises to conduct convective heat exchange with the cold air from the cold air header 3, and the cold air is heated to become hot air that flows into the hot air header 4 and flows out from the hot air outlet 6, The cold air inlet 5 continuously delivers cold air to the quartz glass tube bundle 1, and the concentrated radiant energy flow 7 passes through the absorption of solid particles 2 and the tube wall of the quartz glass tube bundle 1 and the convective heat exchange with the cold air, realizing the conversion of radiant energy to air heat energy conversion.

Figure 2 shows the operating principle of a solar thermal power station using non-compressed air as the heat transfer fluid. During operation, the heliostat field 8 concentrates sunlight to the solid particle stacked bed air heat absorber 10 on the support tower 9 , the cold air 11 in the environment is blown into the solid particle stacked bed type air heat absorber 10 through the fan 12, the solid particle 2 remains in a static state during the working process, and the temperature of the solid particle 2 rises after absorbing solar radiation energy, and the cooling The air 11 is heated into hot air 13 after convective heat exchange with the solid particles 2, and the hot air 13 flows into the steam generator 14 and exchanges heat with the high-pressure water pumped in by the water pump 15 to generate superheated steam, which is input to the steam turbine 16 to do work to drive the generator 17 generates electricity, and the superheated steam after the steam turbine 16 has done work flows back to the steam generator 14 under the action of the water pump 15 after exchanging heat in the water heat exchanger 18 to complete the circulation of the hydraulic medium.

Fig. 3 is the operating principle of a solar thermal power station using compressed air as the heat transfer fluid. During operation, the heliostat field 8 converges sunlight to the solid particle stacked bed air heat absorber 10 on the support tower 9, The cold air 11 in the environment becomes cold compressed air 20 after being compressed by the air compressor 19, and the cold compressed air 20 enters the solid particle accumulated bed type air heat absorber 10, and the solid particle 2 remains motionless during the working process, and the solid particle 2 After absorbing solar radiation energy, the temperature rises, and the cold compressed air 20 is heated to hot compressed air 21 after convective heat exchange with the solid particles 2, and the hot compressed air 21 flows into the air turbine 22 to do work to drive the generator 17 to generate electricity and push the air to compress Machine 19 rotates and does work. After doing work in the air turbine 22, the hot compressed air 21 flows into the steam generator 14 to exchange heat with the high-pressure water pumped by the water pump 15 to generate superheated steam, which is input to the steam turbine 16 to do work to drive the generator 17 to generate electricity. The superheated steam flows back to the steam generator 14 under the action of the water pump 15 after exchanging heat in the water heat exchanger 18 to complete the circulation of the water working medium.

Claims (3)

1. A solid particle stacked bed air heat absorber for a solar thermal power station, characterized in that the heat absorber is composed of a quartz glass tube bundle (1), solid particles (2), and a cold air header (3) , hot air header (4), cold air inlet (5) and hot air outlet (6); the quartz glass tube bundle (1) is composed of a plurality of quartz glass tubes, and the solid particles (2) The inside of the quartz glass tube is filled, and the solid particles (2) are always in a static state during the working process; the cold air header (3) is located at the lower part of the quartz glass tube bundle (1), and the quartz glass tube bundle (1) The lower part of the lower part is sealed; the hot air header (4) is located on the upper part of the quartz glass tube bundle (1), and is sealed with the upper part of the quartz glass tube bundle (1); the side of the cold air header (3) or A cold air inlet (5) is opened at the bottom, and a hot air outlet (6) is opened on the side or top of the hot air header (4). 2. The air heat absorber according to claim 1, characterized in that said solid particles (2) are solid particles resistant to temperatures above 1200°C. 3. The air heat sink according to claim 1, characterized in that the cold air (11) in the environment becomes cold compressed air (20) after being compressed by the air compressor (19), and the cold compressed air (20) enters the solid In the particle stacked bed air heat absorber (10), the cold compressed air (20) and the solid particles (2) are heated to hot compressed air (21) after convective heat exchange, and the hot compressed air (21) flows into the air turbine ( 22) The internal work drives the generator (17) to generate electricity and pushes the air compressor (19) to rotate to do work, and the hot compressed air (21) flows into the steam generator (14) after doing work in the air turbine (22) to be exchanged with high-pressure water. The heat generated superheated steam is input to the steam turbine (16) to do work to drive the generator (17) to generate electricity.

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