Upgrading and replacement potential for older coal-fired power plants

Transcription

1 Upgrading and replacement potential for older coal-fired power plants Dr. Keith BURNARD Senior Energy Analyst International Energy Agency APEC EGCFE Seminar Gold Coast Australia 23 February 2012

2 Scope of presentation Objectives of the joint China-IEA study CO 2 emissions control Coal power in China China-IEA coal power energy efficiency work programme Overall findings

3 Objectives of the joint China-IEA study Aims: to identify potential thermal efficiency improvement for existing coal fired power plants as a means to reduce CO 2 emissions; to evaluate the efficiencies of selected coal fired power plant units; to ascertain the energy saving initiatives that have been undertaken; to identify the scope for further improvements; and to disseminate the results within China and other countries with a significant coal-fired power generation capacity.

4 Reducing CO 2 emissions under the 2DS CCS will have the major role to play in reducing CO 2 emissions from In the short term, the need to improve coal power plant performance through efficiency improvements has become essential to limit the global increase in CO 2 emissions in the power sector.

5 Performance efficiency improvement options Introducing new, larger units with higher thermal efficiencies; Upgrading existing units to improve their thermal efficiency; Ensuring that existing units operate as close as possible to their design efficiency; and Closing older, less efficient units where it is practicable to do so.

6 Potential benefits of improving the energy and environmental performance of coal power plants Link between efficiency and environmental performance is the drive to limit CO 2 emissions

7 Use of SC steam conditions Ultra-supercritical steam turbine Indicative CO 2 emission reduction pathways

8 Potential efficiency increases for existing coal fired power plant Power plant improvements Potential efficiency increase (percentage points) Air preheaters (optimise) 0.2 to 1.5 Ash removal system (replace) 0.1 Boiler (increase airheater surface) 2.1 Combustion system (optimise) 0.2 to 0.84 Condenser (optimise) 0.7 to 2.4 Cooling system performance (upgrade) 0.2 to 1.0 Feedwater heaters (optimise) 0.2 to 2.0 Flue gas moisture recovery 0.3 to 0.7 Flue gas heat recovery 0.3 to 1.5 Coal drying (installation) 0.1 to 1.7 Process controls (installation/improvement) 0.2 to 2.0 Reduction of slag and furnace fouling 0.4 Sootblower optimisation 0.1 to 0.7 Steam leaks (reduce) 1.1 Steam turbine (refurbish) 0.8 to 2.6 USA NETL data

9 Overview of coal power in China Coal dominates the power sector energy mix; It will continue to grow significantly over next decade; There are a wide range of units sizes and ages of coal-fired plant; Present focus is on installing very large, high efficiency units with modern emissions control systems modern units; There is a programme in place to close small, lower efficiency units.

10 Contrasts in the Chinese coal power sector Part of a small power plant being demolished Huaneng Power 4x1000MWe USC PC power plant at Yuhuan

11 Capacity mix for coal fired power plants in China (end-2010) Option No. of units Capacity (GWe) Proportion (%) 1000 MWe USC MWe USC MWe SC MWe subcritical MWe sub <300 MWe sub

12 Plan for the Chinese coal fleet Core size range for coal power plants will be from 300MWe to 1000MWe, and in due course 1320MWe; Will continue to construct new, large, advanced plant and close small units below core size range; Will improve efficiency of existing subcritical units in core size range as well as upgrade emissions control systems to meet new emissions standards; Some focus on the existing fleet of 300MWe units.

13 China IEA work programme Team of international and Chinese experts from the IEA, EDF, VGB, the CEC and the technical staff from two China Guodianowned power plants; Units at two power plants, one in Shandong Province and the other in Jilin Province were selected for audit; Structured interactive approach was adopted Questionnaire Peer review Meetings/discussions

14 Provisional findings for unit in Shandong Province Technical modification Change to adjustable turbine seal CO 2 emissions reduction (tonnes/year) Net efficiency increase (percentage points) 14, Improve air preheater sealing 10, Apply variable speed drives to condensate pump motors Use high frequency power supply for ESP Intended retrofit of the steam turbine flow path 1, , ,000-74,

15 Provisional efficiency data for unit in Shandong Province Boiler efficiency (%) Turbine heat rate (kj/kwh) Net thermal Efficiency (%) Net standard coal consumption rate (g/kwh) Design Performance Test Actual ~91.6 ~

16 Highlights and scope for further improvements Combustion performance was better than benchmark level for 300MWe units; Boiler efficiency was better than the design value; Comprehensive auxiliary power consumption rate was comparatively low; Turbine performance was some 2.2% lower than the design value but will be improved during the proposed retrofit; Scope to lower the exhaust flue gas temperature in the summer with inclusion of a low temperature economiser.

17 Provisional findings for unit in Jilin Province Technical modification Retrofit the flow path of the steam turbine Enlarge the capacity of condenser Cutting the impeller of the condensate pumps to reduce the capacity margin Introduce high frequency power supply for ESP Retrofit to establish as a cogeneration unit CO 2 emissions reduction (tonnes/year) Net efficiency increase (percentage points) 78, , , ,000 (compared to the condensing unit with 170- day heat supply) 2.96

18 Provisional efficiency data for unit in Jilin Province Boiler efficiency (%) Turbine heat rate (kj/kwh) Net thermal Efficiency (%) Net standard coal consumption rate (g/kwh) Design / /320 Performance Test ~ / /321 Actual ~ / /331

19 Highlights and scope for further improvements Combustion efficiency was better than the benchmark level for 300MWe units; Boiler efficiency was close to the design value; Turbine efficiency was very close to the design value; Comprehensive auxiliary power consumption rate was quite low; Exhaust flue gas temperature was acceptable; ID fan power consumption was comparatively high and there will be scope to reduce this; Operations team had no on-line monitoring of coal quality, which needs to be addressed.

20 Overall findings China is improving the thermal efficiencies of its 300MWe coal power units through various measures to ensure performance is at or close to design values. These include minimising air and steam leaks within the boiler components and addressing the steam turbine and its ancillary components.

21 Applicability to other units There appears to be scope for dissemination amongst the 450 or so of the 300MWe units currently operational; Most of these measures should be equally applicable to the very large number of smaller and older 200MWe units; The improvements that have so far been undertaken comprise investments in new equipment and major overhauls of existing equipment. There is scope for additional improvements of this type to be made. In addition, it is strongly recommended that robust operational practice and maintenance procedures are established.

22 Issues for consideration by the Chinese Government The price of coal for power generation is market driven while the power price is regulated. Keeping prices artificially low can lead to wasteful use of power by consumers that, in turn, leads to a greater demand for coal with a consequent increase in CO 2 emissions. Low power plant profitability can limit the level of funding that will be available to pay for efficiency and environmental performance improvements; This distortion can also lead to poor quality coal selected for power stations that, in turn, can lead to higher CO2 emissions and damage to plant components; There is a need for a more integrated national grid system and more scope to improve the power dispatch mode. This would enable the more efficient power plants to operate more regularly at full-load, which would optimise thermal efficiency.

23 Thank you! Keith BURNARD International Energy Agency