Gardner Denver Nash Provides Vacuum Pumps To Enhance Safety For Peterhead Power Station

In October 2006, a visit was made to the Peterhead Power Station in Scotland to discuss the possibility of installing new air extraction pumps. 

The station, a combined cycle operation with three Siemens gas turbines and one steam turbine, is located 55 miles north of Aberdeen on the East coast of Scotland. It had been reporting problems in achieving the desired back pressure on its steam turbine. The existing vacuum pumps, supplied by Gardner Denver Nash UK in 1977, were three 50% NASH CL3005 vacuum pumps with air ejectors and one CL6003G quick start unit.  

Better power efficiency

The vacuum pumps all required service but were basically in good order. Testing indicated good performance and it was apparent that the actual air leaks into the plant were far above the design duty originally specified. Once the pumps and air jets had been serviced, the vacuum levels improved but turbine back pressure was still inadequate, especially in summer months when cooling water temperature was higher.

The power station then started to investigate air leaks throughout the plant which, over time

The power station then started to investigate air leaks throughout the plant which, over time, had increased due to little maintenance and changes to pipe work. In 2007, the first quotation was made to replace the vacuum pumps sets with TC11 two-stage units.

At this point, the station was owned by SSE (Scottish Southern Energy) and their quote, in addition to offering technical advantages over the existing equipment, included better power efficiency. 

Increased energy demand

It had to go through a capital expenditure approval process (CAPEX) during a changing political environment, which was deciding how the UK energy market was to be structured over the next 20 years whilst meeting forecast increased energy demand while producing lower CO2 emissions and meeting EU regulations. This continued uncertainty prevented the station from placing an order.

During this period, the Gardner Denver Nash UK service center in Winsford, Cheshire, continued to work with the power station to support the existing equipment. In 2010, the station downsized its operation from 1,840 MW to 1,180 MW and its available generating capacity was just 400 MW due to high transmission charges.

The owners, SSE, decided to invest £15 million to modify the steam turbine, boilers and control systems to improve the flexibility of the station to meet ‘peaking demands’ and to increase its operating life.

Pre-Combustion carbon capture plant

This project was eventually shelved due to problems with scaling up the plant from pilot schemes

The changes would allow the station to generate power over a larger range, including a minimum output of 200 MW. The reasons for this decision were dictated by the market conditions, the possibility of an independent Scotland and a potential project at the station for the world's first full chain carbon capture and storage (CCS) plant. 

During the four years GD Nash was working with the station, a further project to develop a pre-combustion carbon capture plant was being considered by BP, using the off shore Miller Gas field. This project was eventually shelved due to problems with scaling up the plant from pilot schemes running elsewhere in the UK and the indecision by the government about financially supporting this technology.

Carbon capture and storage (CCS) plant

GD Nash made further quotes for TC9 packages in October 2010 but SSE decided to offer the work as a turnkey solution, which was put out to tender. In 2012, Alstom Technical and Boiler Services, in Gateshead, UK, signed an agreement with SSE to provide the work at the power station. 

This then brought another player into the equation - one that would surely purchase on a price basis with little regard for the long term relationship they had built up with the power station over previous 37 years. 

The UK government announced it would support two CCS projects with £1 billion of investment

At the same time, in 2012, the UK government announced it would support two CCS projects with £1 billion of investment, one project being located at the Peterhead Station. SSE signed a contract with Royal Dutch Shell to build the world's first full chain carbon capture and storage plant on a commercial scale. 

Development of CCS technology

The project is scheduled to be completed by 2020 and will capture one million tonnes of CO2 gas from the flue gas to provide half a million homes with ‘clean’ electricity. The CO2 will be stored in Shell's depleted Golden Eye reservoir; 100 Km off shore and 2.5 Km below the sea bed.

Eight years had passed since the first discussions to replace the existing equipment, during which time changes to ownership of the station, changes in Government parties, changes to government energy policy, changes to EU directives and development of CCS technology all played some part in the final decision.

Air leakage rates

Finally, after further meetings with Alstom's technical department, further analysis of the air leakage rates and four more revised quotes, Alstom awarded the contract for three TC9 units to GD Nash in July 2014. 

Their competitors were Busch and SIHI. The contract award was Euros 365,000. With all of this investment, the Peterhead Power Station will be the most efficient station in the UK and the cleanest fossil fuel power station in Europe.

Its design flexibility will ensure its longevity and its contribution to the UK's overall energy mix of nuclear, wind and fossil fuel. They look forward to a further 30 years of ongoing support to this power station and the chance, in 18 months, to purchase back the existing CL3000 and CL6000 pumps for use in their service exchange pump program.