Why can the heat absorber of the first high-tech solar thermal power station be listed as the first (set) major technical equipment in the energy field?

Time:2023-01-13

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On May 13, the National Energy Administration issued the "National Energy Administration Announcement No. 2 of 2022", and decided to list 75 technical equipment (projects) such as "300MW variable speed pumped storage unit complete equipment" as the energy field in 2021. The first (set) major technical equipment project,The first high-tech 100MW molten salt tower-type thermal power station heat absorber "is listed among them.

 

 

As one of the key equipment of the photothermal power station, the heat absorber is like the "heart" of the photothermal power station ". It plays a vital role in absorbing solar energy in the operation of the whole tower solar thermal power station. Its operation reliability and performance, as well as the coupling with the concentrator system and heat storage system, directly affect the safety and economy of the entire power station.

 

 

Based on the working characteristics of the heat absorber in the tower-type photothermal power station, its technology has the following characteristics:

1) The incident load is large, the local heat load is high, and the heat load distribution is uneven.

2) sensitive to surface temperature changes.

3) The surface temperature of the position directly receiving solar radiation is high, and the temperature gradient changes greatly, and the thermal stress is sensitive.

4) The condensing ratio is high, and the surface temperature of the equipment is high.

5) Start and stop at least once a day, with serious thermal fatigue.

6) The installation height of the heat absorber is relatively high, which has a large impact on the descending pipeline and is prone to vibration.

 

And because of the above characteristics, the difficulty of the heat absorber technology is large and the technical content is high. after years of exploration and practice,Shouhang High Tech has mastered the design, production, installation and commissioning technology of a full set of heat absorbers, established a complete technical system, and formed the core process design package of heat absorbers for 100MW power stations.

R & D Design:

The condensing and heat transfer process on the surface of the heat absorber is a complex process of photothermal aggregation, conversion and coupled heat transfer.The heat absorber is an external type, and its convective heat loss has a great influence on the thermal efficiency of the heat absorber. Therefore, how to solve the instantaneous heat flow distribution on the surface of the heat absorber and how to solve the heat absorption of the heat absorber are the basic input conditions that determine the design, and it is also a difficult problem.

 

 

According to the heat flux distribution on the surface of the heat absorption screen, the first flight research and development team used numerical simulation to obtain the temperature distribution and thermal stress of the heat absorption tube, so as to ensure that the heat absorber operates under the temperature and stress range permitted by the material. At the same time, in order to ensure the optimal effect of the flow characteristics of the heat absorber, the pressure drop of the heat absorption system is calculated by empirical formula and CFD analysis of fluid dynamics, and the structure of the heat absorber is continuously optimized.

 

Production and manufacturing aspects

1. Due to the requirements of the working conditions of the heat absorber, the materials used in the heat absorber need to have high temperature resistance, high temperature fatigue resistance and other characteristics, and a new high-temperature alloy SHBG-2 has been developed.

ByThe heat absorption system is faced with frequent start-stop and load rate changes, and changes in cloud cover also require the heat absorber to have high adaptability and anti-fatigue performance. At present, the development of heat absorber materials is a technical barrier for domestic enterprises, and Shouhang is committed to the development and research of alternative materials to promote the localization of core materials in the manufacture of heat absorbers. Shouhang cooperated with Baosteel to develop the domestic nickel-based alloy material SHBG-2. Through the unremitting efforts of the research and development team, it has overcome the difficult SHBG-2 deformation and other process difficulties. At present, it has been successfully used in the two photothermal power stations built by Shouhang.

 

 

2. The manufacturing process is innovative, the heat sink header adopts the self-developed production process, and the header has superior fatigue resistance.

SuctionThe difficulty in the manufacturing process of the heater lies in the production process of the header and the welding of the thin-walled metal tube, and the characteristics of the operating conditions of the heat absorber determine that the header has a large fatigue stress level. After continuous exploration and testing, the first flight broke through the new production process of the header, and obtained the heat absorber header with excellent fatigue resistance. The heat absorption screen welding production line also adopts automatic welding, and the welding current is strictly controlled during the welding process to ensure the welding quality. The non-destructive testing of the endothermic screen includes 100% non-destructive testing, 100% penetration testing, hydraulic testing and other processes to ensure that the product is defect-free, and the design and manufacture of the entire heat absorber are completely independent.

 

3. Structural innovation, the heat absorber and its ancillary equipment, pipeline support structure adopts a reasonable layout, to meet the requirements of the support conditions, saving weight. 

Due to technological innovation and reasonable arrangement, the weight of the equipment and steel structure above the 212-meter conversion layer platform of the heat absorption tower in the Dunhuang 100MW molten salt tower photothermal power station demonstration project is far less than the load of more than 2000 tons in other projects..

 

 

During the development of the heat absorber of Shouhang Gaoke Photothermal Power Station, it has broken through many technical difficulties, achieved major technological breakthroughs, and has independent intellectual property rights.Dunhuang 100MW molten salt tower solar thermal power station demonstration project is the first project to be connected to the grid among the first batch of solar thermal demonstration projects in China, and it is one of the only two 100MW molten salt tower solar thermal power stations in operation in the world. The power station has been running smoothly for three years, which proves the good performance of its heat absorber. The complete operation control strategy of the heat absorber ensures the safe and stable operation of the heat absorber under various working conditions, especially under sudden conditions.