Jorf Lasfar Gets an Energy Boost
Improving plant performance can be as simple as evaluating severe service control valves. Are they the right design for their application? The reality is, the better the performance of the valves, the better the performance of the plant. Such a gain was realized with the replacement of severe service valves in Unit 1 of Jorf Lasfar Power Station (JLEC), Morocco. The third phase of the collaborative effort undertaken by JLEC and CCI, the valve project was designed to improve the performance of Units 1 & 2 through the elimination of valve-related inefficiencies in the SH spray, steam drain, HP7 emergency drain and HP6 inlet line drain applications.
Losses due to the old valves amounted to a penalty in heat rate of 1.54%, which is equivalent to a 5.1 MWe. In the case of SH spray valves, leakage was occurring at low load when these valves were shut. Leakage was also an issue for the heater emergency drain and heater inlet line drain valves, which resulted in a loss of production and MW-capacity.
Every additional MW in capacity that is recovered is like installing a new MW Unit.
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The approach of recovering performance on the account of valves is most relevant in the discussion of plant optimization and efficiency enhancement.
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| Every kilogram of fuel saved lowers the cost of power generation and helps reduce emissions. |
The new CCI valves, installed in the Jorf Lasfar Unit 1 during the 2001 major overhaul, were custom-designed based on recommendations of the Plant Betterment study conducted earlier. The new valves contributed an equivalent of 5.5 MWe, and eliminated the problems of the previous severe service valves. The economic benefit in terms of savings in coal consumption was 15,000 tonnes of coal annually.
Additional benefits were also realized with the installation of these new valves: better vacuum in the condenser, which increased the useful work in the turbine and improved overall steam cycle heat rate; and overall cleaner operation on the combustion side with better life expectancy for expensive plant equipment such as turbine and boiler tubes/headers. The most important to Jorf Lasfar, however, is the additional production of 38,500 MW-hours annually.
Care must be exercised that the spirit of this collaboration between JLEC and CCI is maintained at all times. The work is engineering-intensive at all stages, and staff in both these organizations had to work closely to ensure 100% success.
| How to improve plant efficiency |
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| Small contributions to loss in plant efficiency from individual valves add up to be a significant value. Systematic elimination of these losses can be done in steps as follows: |
- Quantify the individual losses.
- Determine the root cause of problems and apply solutions to eliminate the losses.
- Verify that the projected savings are realized.
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Recent studies indicate that eliminating control valve problems alone can improve the heat rate of power plants in the range of 2% to 5%.
Published in SOLUTIONS Spring 2002
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