Highlights of the First Flight Energy-saving Photothermal Project




The first 10MW tower type molten salt photothermal project in Dunhuang (already in operation)

On December 26, 2016, the Dunhuang 10MW tower molten salt photothermal power generation demonstration project independently invested and constructed by Shouhang Energy Conservation was successfully connected to the grid for power generation. This is the third molten salt tower in the world and the first in Asia that can achieve 24-hour continuous power generation. Photothermal power station. The first flight energy conservation project was started in October 2014, covering an area of 120 hectares with a total investment of 0.42 billion yuan. 1525 heliostats are arranged in a ring around a 138.3-meter-high heat absorption tower. The two heat storage tanks of the heat storage system have a diameter of 21 meters, a height of 10 meters and a molten salt reserve of 5800 tons. Their heat storage capacity can supply 10MW steam turbine generator sets for 15 hours.

Figure: 10MW unit of the first voyage to Dunhuang

The first 10MW unit in Dunhuang is a demonstration unit for the subsequent phase II 100MW tower molten salt photothermal power generation project. It not only provides experiments and tests for various system design and equipment selection of the 100MW project, but also provides talent reserve and technical reserve for the 100MW project. At the same time, the operation mode that meets the requirements of China's resource conditions and power grid dispatching is explored.

After 5 years of reserve, two years of construction and commissioning, and more than 4 months of trial operation, Shouhang Company has conducted a large number of system tests and product experiments, accumulating a large number of talents for the construction and operation of the tower molten salt photothermal power generation project. Data, experience and lessons.

Spotlight System Aspects

The production of heliostats adopts an automated production line, and a standardized workshop is built at the project site. A sub-mirror automated production line, a heliostat automated assembly line and a heliostat automated optical performance inspection line are installed. It took 5 months from installation to commissioning. One month earlier than expected.

Heat absorption system aspect

The top platform and steel structure of the heat absorber were installed for 21 days, the heat absorber was installed for 9 days, and the thermal protection was installed for 35 days. It took a total of 65 days, 15 days earlier than expected.

Heat storage system aspects

The salt took 17 days from the beginning to the end, and the molten salt was filled successfully once, which was consistent with the design time.

During the commissioning phase, 57 commissioning items were completed for the heat absorption, heat storage and evaporation systems, which was 30% shorter than expected. However, some projects did not meet the expected indicators, such as the arrival time of some imported valves and the installation of electric heat tracing. These experiences have laid a solid foundation for the construction, commissioning and operation of the second phase 100MW project.

The first voyage energy-saving Dunhuang 10MW project is connected to the grid in winter, which is a severe challenge for the solar thermal power station. Because the light resources before and after the winter solstice are the worst time of the year, especially in northwest China, there is also the problem of low meteorological temperature. This season is a severe challenge for both the concentrating heat absorption system and the conventional steam turbine generator set. Fortunately, with the cooperation of domestic and foreign photothermal experts on the first voyage, we have overcome various difficulties and achieved a successful grid connection, which has also strengthened our confidence in the adaptability of the tower molten salt power station to extreme climate.

Figure: cleaning heliostat

The first 10MW Dunhuang project was positioned as a 100MW prototype from the beginning, and undertook a number of tasks of equipment testing, process optimization and operation improvement.

The construction of the power station began in 2014, and the design of its key equipment, such as heliostats, heat absorbers, storage tanks, molten salt system, and steam generation system, was completed by the engineers of the first voyage. Due to the reference to the past development experience of Europe and the adaptation to the climate characteristics of Dunhuang, it has reached the world's leading level in many technical aspects, which can be used as a reference for the future larger-scale heat storage tower power station with molten salt. During the first six months of operation of the power plant, our main objective will be to test the various systems of the power plant, understand the operating characteristics of the systems, and optimize the overall operation of the power plant.

During the commissioning of the power station from September to December 2016, we have accumulated a lot of experience that will be applied to the larger units being developed at home and abroad.

After the commissioning period, we also arranged a series of tests, from the cleaning of the heliostat, to the measurement of mirror reflectivity, the measurement of atmospheric loss, the calibration method of the heliostat, the stress measurement of the absorber tube under different thermal power, the operation evaluation of the storage tank and the calculation of heat loss, the operation evaluation of evaporation start, the coordination of the steam turbine and the evaporation system, and the research on the more efficient start-up method. These tests can help the first company to have a deeper understanding of the performance of the equipment; at the same time, the domestic and foreign suppliers of various equipment have been evaluated, such as valves, molten salt pumps, molten salt meters and control systems, and have reached cooperation agreements with suppliers of key equipment. These suppliers have demonstrated their level and ability, and said that they can better provide the basis for the design, equipment selection, installation and commissioning, operation and maintenance of the second phase 100MW project. This is also an important guarantee for the success of Shouhang Company in future projects.

In the more than 100 days since the start of the machine, in addition to the cold winter, it has also experienced the spring of wind and dust in the northwest. From New Year's Day this year to the end of March, there were 89 natural days, but only 67 days were available. Since the winter solstice has just passed, DNI is not very good, but most of the daily heat storage reaches the model prediction. In the past few months, we have conducted a large number of scientific experiments. For example, we have tried various operating modes of steam turbines. According to the experience of trough heat transfer oil power station, many people think that the power generation of steam turbine is closely related to the heat absorber. Some people also put forward the problem of the joint start-up curve of heat absorption and power generation. In fact, this problem does not exist, especially the power station with heat storage time exceeding 6 hours. Heat absorption and power generation are completely decoupled, and joint start-up is not necessary at all. For example, we designed a number of operating modes in our test, one of which is two natural daily heat absorption and heat storage. After the storage tank reaches the limit, the steam turbine runs at rated load until the hot salt is used up. Another mode is to absorb heat and store heat every day, and the steam turbine is also running. The running time of the steam turbine is relatively short, and it needs to be started and stopped frequently. Multiple sets of experiments were performed to compare the heat consumption of each mode to correct our design calculation model.

Figure: Typical Operating Lines

The above is the typical operation curve of Dunhuang 10MW tower molten salt solar thermal power station. It can be seen that the power generation curve is smooth during operation, the power output of the power station is not affected by the change of sunshine conditions, and it can continuously generate power day and night. The power generation load adjustment is flexible and stable, which is a friendly power generation mode for the power grid. From the second half of the curve, it can be seen that after several months of operation training, it has been very skilled in dealing with bad cloudy weather, to the greatest extent, the coordinated, efficient and stable operation of the heat collection and heat absorption system is guaranteed.

[2] first voyage Dunhuang 100MW tower molten salt photothermal project (under construction demonstration project)

On November 9, 2015, before the list of the first batch of national photothermal demonstration projects was announced, the foundation of the first energy-saving Dunhuang 100MW tower molten salt photothermal power station was laid. After the list of demonstration projects was announced, the project entered a period of rapid advancement. According to the latest news, the project is currently undergoing the construction of heat collection towers and ancillary facilities. The height of the heat collection tower has now reached 57 meters, and it is currently advancing at a speed of 1.5 meters per day, it is expected that the civil works will be completed to the top by the end of August this year, with a built height of 261.3 meters. At that time, the project will surpass the 243-meter height of the NoorIII solar thermal power station in Morocco under construction and become the world's highest tower power station. At the same time, the structural construction of the office building in the front area of the factory of the project was completed on May 13, and it is expected to be completed in July and put into use in September. In terms of overall progress, the project ranks first in the first batch of 20 demonstration projects, second only to the 50MW trough power station in Delingha, which started earlier.

Construction Site of 100MW Photothermal Power Station in Dunhuang

Construction Site of 100MW Photothermal Power Station in Dunhuang

[3] CGNPC Delingha 50MW Trough Photothermal Power Generation Project (Light Field EPC)

On April 6, 2016, the first voyage energy-saving consortium won China's first commercial solar thermal power generation project, Guanghe Delingha 50MW trough solar thermal power generation project light field EPC general contract order, becoming the only domestic company with both tower and trough solar thermal power generation project performance.

Figure: CGNPC Delingha 50MW Trough Solar Thermal Power Generation Project Assembly Site

Construction Site of 50MW Trough Solar Thermal Power Generation Project in Delingha of CGN

[4] Dubai Solar Park 200MW solar thermal power project (bid shortlisted)

In January 2017, the consortium composed of Shouhang Energy Conservation and Saudi Alfanar stood out from the competition of more than 30 bidding consortia and was successfully shortlisted for the 200MW solar thermal power project in Dubai Solar Park. This is a major breakthrough made by domestic solar thermal power generation independent technology manufacturers in the international solar thermal market. If they finally win the bid, it is expected to realize the core technology and equipment of domestic solar island for the first time.

Up to now, Shouhang Energy Conservation has signed nearly 2GW solar thermal power development project contracts with various local governments, and has completed the layout in Qinghai Province, Gansu Province, Inner Mongolia, Hebei and other places. In the future, it will gradually develop Xinjiang and Ningxia., Shaanxi, Yunnan and other markets.