Small Units, Major Transformation and Setting up Examples (Going into Frontlines)
14-10-2019 China Energy News

As at the end of 2018, China has had 350 million KW of subcritical units, and 943 0.3 million KW subcritical units. The power supply coal consumption of such units under rated conditions was generally higher than 320 g/KWH, and the actual coal consumption of a lot of units even exceeded 340 g/KWH.


After the comprehensive high-temperature subcritical upgrade and transformation, the designed power supply coal consumption of 0.3 million KW unit of Xuzhou CR may decline to 287 g/KWH, close to the actual level of ultra supercritical units, which will play a typical demonstration role in enhancing the power generation efficiency of a lot of stock subcritical units.


"Only after revolution, can subcritical units keep continuous profitability and indicator advantages during future competition. The market competition of 0.3 million KW units weakens continuously, it is necessary to dig their potential as compared with 1 million KW units. In that light, we have conducted the comprehensive high-temperature subcritical upgrade and transformation for the 0.3 million KW unit." A few days ago, Chen Chaohu, deputy general manager of Xuzhou/Tongshan CR Power Co., Ltd. (the "Xuzhou CR"), introduced to visitors during the public open day activity.

 
It is learnt that the 0.3 million KW unit No. 3 of Xuzhou CR is the first unit upgraded from a straight subcritical units into a ultra supercritical unit in the world, and is under the pilot project of "comprehensive energy conservation upgrade and transformation of subcritical units" of CR Power. The upgrade and transformation were conducted against the background of elimination of backward production capacity and high coal consumption indicator control under the "13th Five-year" Plan on national power development, setting an industry benchmark for green thermal power in China.


Conduct demonstration by technical innovation


As per relevant state requirements, the average power supply coal consumption of new units in China should not exceed 300 g/KWH by 2020, and that of active units should not exceed 310 g/KWH. As at the end of 2018, China still had 350 million KW of subcritical units, and 943 0.3 million KW subcritical units. The power supply coal consumption of such units under rated conditions was generally higher than 320 g/KWH, and the actual coal consumption of a lot of units even exceeded 340 g/KWH.


Against such background, CR Power, together with Shanghai Shenergy Technology, transformed Unit No. 3 of CR Xuzhou Power Plant by high-temperature subcritical technologies, and smoothly passed the 168-hour full-load trial operation this August. After the upgrade and transformation, the designed power supply coal consumption of the unit may decline to 287 g/KWH, close to the actual operation level of ultra supercritical units.

 
According to statistics of Long Hui, deputy chief engineer of China Energy Engineering Group Planning & Engineering Co., Ltd., the coal-fired thermal power installed capacity of China has exceeded 1 billion KW as at the end of 2018; in 2018, average power supply coal consumption reached 308 g/KWH, reaching the advanced level in the world. "However, the ultra-low emission indicator of China has been lower than the lowest standard overseas, so the room for further improvement will be restricted in all aspects."


What does the decrease of the coal consumption of the 0.3 million KW coal-fired unit of Xuzhou CR to 287 g/KWH mean?


"The successful transformation of Unit No. 3 plays a typical demonstration role in enhancing the power generation efficiency of a lot of stock subcritical units in China, and is of deep influence for activating the vitality of subcritical units and enhancing resource utilization rate." Chen Chaohu told the journalist.


Conserve energy, reduce consumption and be economical

 
Concerning the pilot project of "comprehensive energy conservation upgrade and transformation of subcritical unit", a contract was contract for the start of design in April 2017, and the on-site construction started in December 2018. On August 10 this year, the project was smoothly passed the 168-hour full-load trial operation. All performance indicators and environmental protection indicators of the unit reached excellent levels.


It is learnt that supercritical units and ultra supercritical units of thermal power plants are classified by the pressure of working medium in boilers. The critical pressure and critical temperature of water in boilers are 22.115 MPa and 374.15 ℃ respectively. Where the steam parameters of a unit exceed the parameters of water at the critical state, such unit is called supercritical unit. The coal-fired power generation technology of ultra supercritical units outperformed that of supercritical units by about 4% in terms of thermal efficiency, and is more advantageous as compared with that of conventional coal-fired power generation units.


What makes the energy consumption of 0.3 million KW units better than that of 1 million KW units?


The technical principal of Xuzhou CR introduced: the ultra supercritical coal-fired power generation technology can keep the pressure of units unchanged at the subcritical level, increase the temperature of main steam and reheated steam of units from 540 ℃ to 600 ℃, and ensure no change in the type of drum boiler and the outer cylinder of steam turbine, with all internal components and parts of steam turbine changed. Upon estimation, the comprehensive performance such as energy conservation, environmental protection and flexibility of units have been improved comprehensively.


Regarding the project economy that the outside is concerned about, Zhang Feng, technical director of Xuzhou CR, calculated as below: "As calculated as per a decrease in power supply coal consumption of 31 g/KWH, the standard coal of 54,560 tons can be conserved each year, under the heat consumption rate acceptance conditions. As calculated by the standard coal price of RMB760/ton, the fuel cost can be reduced by around RMB40 million each year. The investment of the project totalled over RMB300 million, and can be recovered after 7 to 8 years."

 

Emphasize green and environmental protection at the very beginning


Xuzhou CR established in 1994 is the first thermal power enterprise of CR Power and the source of the spark of CR Power.


Different from power companies established before, Xuzhou CR is a new power company fully independent from the power system, and was incorporated in strict accordance with requirements of modern enterprise system. Different from the traditional power generation pattern with the separation of constructor from operator and the disconnection between construction management and operation management, Xuzhou CR has explored a route of self-construction, self-management and self-operation, created the "Pengcheng mode", and opened the "test field" of power reform of China.

 
As early as the establishment of Phase 1 of 0.3 million KW units in 1996, Xuzhou CR designed environmental protection facilities as per domestic advanced technologies, and adopted efficient electrostatic precipitator, with the efficiency of dust collection reaching over 99.5%; realized the recycling of industrial waste water; converted coal ash into construction materials, with the comprehensive utilization rate of 100%. Chen Chaohu introduced that Xuzhou CR had cumulatively invested over RMB1 billion in environmental protection transformation.

 
From 2014 to 2015, Xuzhou CR invested about RMB300 million in the comprehensive energy conservation transformation of 1 million KW units. Chen Chaohu stated: "As calculated by the annual power generation capacity of 11 billion KWH of Tongshan CR, the power supply coal consumption declines by 10 g/KWH after the transformation. The Company can conserve 0.11 million tons of standard coal each year, and realize energy conservation benefits of around RMB86.9 million as calculated by the unit price of RMB790/ton of standard coal."

 
From 2015 to 2017, Xuzhou CR completed the ultra-low emission transformation of 6 units by the investment of RMB300 million, with all emission indicators of atmospheric pollutants such as dust, sulfur dioxide and nitrogen oxide reaching emission standards of compressor-turbine units and better than state standards, the general pollutant emission amount decreasing by 75% as compared with that before transformation, and realizing the "desulfurization, denitration and dedusting" of the whole plant. Meanwhile, Xuzhou CR strengthened coal yard covering and flying dust management, strictly control unorganized emission, and planned to invest RMB200 million in the closed transformation of coal yard. At present, the project has entered into the phase of on-site construction.


Link: http://paper.people.com.cn/zgnyb/html/2019-10/14/content_1950517.htm