The first flight energy saving won the "national excellent development unit of solar thermal power station"




Recently, the 2017 National Photothermal Power Station Design and Equipment Selection Seminar and China Photothermal Power Generation Quality and Standards Conference was held in Xi'an. Shouhang Energy Saving was invited to participate in the forum and won the "National Excellent Development Unit of Photothermal Power Station".

Representatives of the first flight received the award of "National Excellent Development Unit of Photothermal Power Station"

Experts related to photothermal technology gathered in this forum, including Hu Runqing, a researcher from the Energy Research Institute of the National Development and Reform Commission, Sun Jihong, a professor-level senior engineer from the General Institute of Electric Power Planning and Design, and Wang Zhifeng, vice chairman of the National Solar Photothermal Power Industry Technology Innovation Alliance. Some policies, standards, design and equipment selection issues in the power generation project were elaborated and discussed in depth.

The first flight energy saving has been carrying out photothermal power generation business since 2010. Up to now, it can be said that it has gone through three stages: the first stage, 2006-2009, is the learning and strategic positioning stage, the second stage, 2010-2013, is the R & D and experimental stage, and the third stage, 2014-present, is the stage of commercial project development and industrial scale.

According to the construction experience of the tower-type photothermal power station at first voyage energy saving, its design and equipment selection analysis are as follows: the collection of sunlight is carried out by heliostats, and the concentrating capacity, procurement and operation and maintenance costs of heliostats become the basic data for mirror field performance and technical and economic evaluation. The concentrating capacity mainly includes parameters such as reflectivity, spot quality and attenuation, tracking and transmission accuracy, correction capability, etc. The early maiden voyage also tested the quality of the spot. It is also based on this that the heliostats we developed later are all designed with a back plate.

Figure: The first flight energy-saving on-site heliostat

Based on the global completed and under-construction projects and years of experience in the development, production and manufacturing of heliostats, our heliostats have undergone continuous changes from the first generation to the fifth generation since 2010. The final development appeared in the fifth generation of heliostat products. For example, the first 10MW project in Dunhuang will use SH4 generation products, while the second 100MW demonstration project will use SH5 generation products. The comparison between the 4th generation and the 5th generation is mainly in the transmission mode, which is upgraded from gear transmission to RV cycloid transmission with higher transmission efficiency, higher transmission accuracy and stronger resistance to instantaneous impact.

Of course, this only roughly reflects the more macro direction we are developing heliostats, specifically we have parameterized the core indicators. These parameters are very critical in the subsequent arrangement and optimization of the mirror field. In the end, we are pursuing the investment return rate of the photothermal power station. Under the condition of the same DNI input time by time, after calculation, the optimal investment return rate between different generations is also higher generation by generation. At the same time, the mirror field can be made larger generation by generation and can support larger capacity generation by generation. Therefore, we believe that there is room for improvement in the size of a single tower, and technical optimization can also reduce the cost of levelized energy (LEC).

The coupling between the mirror field and the heat absorber is also very critical, and the light spot overflowing the heat absorber will cause energy loss and a decrease in the overall heat absorption efficiency. The figure shows the simulated light spot under different surface parameters:

Figure: Surface sigmaSLR = 2.5mrad

Figure: Surface sigmaSLR = 1.6mrad

Figure: Surface sigmaSLR = 0.8mrad

Fig.: Spot of Field Heat Receiver

Based on the excellent performance and good control ability of the condenser system, combined with the parameter logic simulation of various working conditions of the heat absorber, and the process realization of the material and structure, the average rated power of the first heat absorber can reach 750KW/㎡, which is the highest parameter in the tower power station in the world.

Of course, the above is only a small part of the work on the optimization and selection of the concentrator and heat absorption system and its equipment. The rest include the optimization of the mirror field in different combinations of mirror field area, heat absorber power and heat storage time, the optimization of tower height and so on, which are all based on the optimal investment income and calculated with actual technical parameters and implementation cost. The concentrator and heat absorption system can refer to fewer cases and the system is more complex, the use of economic and technical models for comprehensive assessment can avoid human decision-making errors caused by inexperience and one-sidedness. Here, the construction of the model and the acquisition of basic data are the key.

In the closed-loop heat exchange power generation, it is relatively conventional and the technology is more mature, but it is very important to the economy of the whole system. First of all, the stability and reliability of the system should be guaranteed. The light and heat electricity price is 1.15 yuan. When the equivalent daily power generation hours are 20 hours, the daily power generation income of the 100000 unit will be more than 2 million yuan. If the shutdown is caused by failure, the loss will be huge. In the selection of key equipment such as molten salt pump and molten salt valve, we think whether there is mature and stable application performance is an important inspection item. Moreover, the steam turbine should try to choose efficient units. This increased investment accounts for a small proportion of the whole system, but it is the shortest board in the barrel effect.