The Health & Safety Executive has identified a risk of explosion in gas-fired power stations and is requiring the plants’ operators to eliminate it.
The boxes built around the gas turbines to reduce their noise present the potential hazard – the HSE considers these acoustic enclosures do not have adequate ventilation or detection systems to prevent dangerous build-ups of gas in the event of a leak.
While the risk applies to all enclosed turbines, like those on British Gas compressor stations, the size of the units on combined-cycle gas turbine (CCGT) plants and the proximity of workers make them the main cause for concern.
`Turbine engineers are acutely aware of the problem,’ said a senior engineer at one operator. `All plants are in various stages of analysis or implementing a solution.’
Keadby Generation will be the first to implement a permanent solution when it installs a new ventilation system in the turbines on its 680MW plant in Yorkshire next month.
A study last year by AEA Technology used computational fluid dynamics to establish that there was a greater chance of large gas accumulations building up inside the turbine’s 640m3 box than had been previously anticipated.
As an interim measure, the operator installed new sensors to detect lower levels of gas, while it devised an improved ventilation system with AEA and Kvaerner John Brown, Keadby’s turnkey contractor. The HSE approved this in April.
National Power, the UK’s largest generator with three operating CCGT stations and a fourth under construction, could not comment. PowerGen has done risk assessments for its CCGT plants.