Mirek Spicar reports on a valuable support tool for cleaning of large supercritical power plant boilers
The first phase of an innovative project saw four TwinL Shock Pulse Generators (SPGs) installed into a supercritical pulverised coal boiler of 660 MWel capacity in 2018. They have operated successfully in support of boiler cleaning and keeping the required flue gas outlet temperature within design specifications (inlet to SCR catalyst elements) since then. Due to operational satisfaction, as part of the second phase, the Thai power producer purchased an additional four TwinL SPGs for saving feed water and steam leading to cycle optimisation in 2020. In the third phase, which will be undertaken in 2021, an additional four units will be installed in the furnace – where the temperatures are about 1,300°C – for the reduction of deposits.
Gheco-One Co is a leading private and state-owned producer of electricity in Thailand. The supercritical pulverised coal-fired boiler of 660 MWel capacity produces 2,079 t/h steam of 243 bar and 568°C, incinerating sub-bituminous coal. To protect the SCR catalyst elements, it is necessary to maintain the boiler flue gas exhaust temperature below 400°C. Originally the boiler was equipped with a total of 92 soot blowers.
Shock pulse generators as the solution
Explosion Power, with support of the local distributor Vannetto, was chosen to mitigate the unfavourable conditions upstream of SCR in a 24m wide back-pass chamber.
In the first phase, in April 2018, Gheco-One installed four SPGs (two per side) to assist the soot blowing system in keeping the primary reheater, primary superheater and economiser clean and protecting the sensitive SCR element from excessive heat. The shock pulse intervals were set to 60 minutes, which has proven to be the most suitable pulse frequency. Two long, retractable soot blowers are kept in operation per SPG.
Due to excellent experiences an additional four TwinL SPGs were installed in 2020 to reduce the sootblowing operation as much as possible and by doing so, save feed water and steam. The whole boiler cleaning system is activated from the central DCS.
Further shock pulse generator installations for phase three
To achieve a significant cleaning improvement in the furnace, this current third phase includes an additional four SPGs of the established TwinL type within this furnace area. The incineration temperature is about 1,300°C and the ashes tend to settle down on the walls. The main aim of this measure is to reduce deposits in the particular area of the furnace above the wall sootblowers by means of the continuous cleaning that has already been proven with the SPG technology.
Mirek Spicar is with Explosion Power