Earlier this year in May, I provided a further blog in my series of articles looking at the amazing drive and innovation from the Shanghai Shenergy Power Technology Co Ltd Team under the leadership of Professor Feng Weizhong who now is an independent consultant engineer. I reported that they continued to identify and demonstrate further significant energy efficiency and environmental performance advances that are possible either as new build or retrofits within China’s coal power fleet. These can provide robust, cost effective solutions for meeting China’s increasingly strict efficiency and environmental control standards. At that time, I presented information and comment on four major initiatives, which included the following two very important retrofit options.
The Team worked with China Resources Power to uprate its Caofeidian 2×1000 MWe USC power plant that had been put into operation in April 2019. This Caofeidian plant became the first one in China to incorporate 3 LP casings for the steam turbine, thereby achieving a 3.3 kPa ultra-low back pressure, to take advantage of low temperature cooling seawater as it is located at the coast. This plant now has a design net efficiency of 46.7% under rated conditions, which is even higher than that of the current double reheat units in China. Moreover, after one year’s operation the operational data indicate that the annual average net efficiency can reach 45%. This represents an excellent return on investment since the capital cost is about 85% of that for a typical 1000 MWe double reheat plant.
The other upgrade demonstration project was also undertaken with China Resources on a 320 MWe subcritical unit at Xuzhou coal power plant, Jiangsu Province, China. This had typical steam conditions of 16.7 MPa/537°C/537°C and began commercial operation in June 2004. The changes comprised an increase in the maximum temperature of the main and hot reheat steam from 538/538°C to 600/600°C, while keeping the steam pressure unchanged, together with other energy-saving technologies. Together they have achieved significant advances in coal power plant operations with improved energy and environmental performance.
This innovative approach in China has provided the basis for the major upgrade of the relatively young 300-600 MWe subcritical coal power plant units, which represent about 32% of China’s coal power fleet capacity. It will achieve not just a reduction in carbon dioxide emissions but will also ensure better use of fossil fuels with much improved environmental performance, in line with the aims of the UN Sustainable Development Goals.
The operational cycle efficiency on the Xuzhou plant improved from 38.63% to 43.56%, an increase of almost five percentage points. The new level is equivalent to that of an early ultrasupercritical (USC) unit. If these improvements are applied to the large number of 300-600 MWe coal power units, this will significantly boost the national efficiency of the global coal fleet, resulting in a corresponding reduction in coal use and lowering of CO2 emissions. Equally important, this modified unit successfully achieved a lowest stable load of 19%, with a much shorter response time from low load to full operation compared with the 600-1000 MWe supercritical and USC units. Consequently such upgraded subcritical units will provide a very flexible means to balance and stabilise the grid, both in terms of the ability to maintain a low load (<20%) and a fast response to load following demands due to the need to integrate intermittent variable renewable energy options. This upgrade approach represents an excellent return on investment as the cost is about one third of that for building a new unit, while achieving so many advantages. It can be applied as a major upgrade of the 300-600 MWe subcritical coal power plant units, which represent about 32% of the coal power fleet capacity in China.
I am also very pleased to note that their success has been recognised by Power Magazine, which has presented both projects with its TOP PLANTS award. You can read more about each project in the two magazine articles that can be accessed via the links below.
My congratulations to Prof Feng Weizhong, Mr Li Li and the rest of the team for this well-deserved international recognition by POWER Magazine.