Varnish removal in the Thailand power plants

Varnish removal in the Thailand power plants

HYDAC Australia / New Zealand’s Varnish Elimination Units (VEU-F) have been used on several power plants throughout Thailand. One of the successful examples was in Bang Pa-in power plant.

Bang Pa-in Co-Generation operates a natural gas-fired power plant and produces electricity and steam. The company was incorporated in 2009 and is based in Bangkok, Thailand. The plant has a power unit with a 12,000 litres oil tank, the operating temperature is 72°C and the turbine oil used is the Mobil DTE 846.

The problem

The oil tank presented a deposit of oil that was rapidly ageing. Varnish in the system was causing several problems.

The initial MPC (Membrane Patch Colorimetry) value was 52.16.

The goals were to reduce this value and have a more reliable plant operation.

What is varnish

When hydraulic and lubricating oils age and oxidise, the colour of the oil will change. This is due to the build-up of damaged and degraded elements in the oil. In Group 2 and 3 oils, varnish forms, this is a sign of oil degradation.

What is MPC

By analysing the colour change of the oil, we can check the level of varnish present in the oil and assign a number to the colour in order to quantify and report on its condition. This method is called Membrane Patch Colorimetry or MPC.

The solution

In order to reduce the varnish efficiently, AEROFLUID Group (company located in Thailand) provided to the power plant an HYDAC VEU-F (Varnish Elimination Unit) solution. The service-friendly units are particularly effective in removing oil ageing from mineral oils.

The VEU-F-AU has the unique characteristic of being a fully “online and on load” treatment sub-system, allowing varnish removal and clean-up of the oil whilst the system is operating.

After a month of using HYDAC’s VEU-F, the MPC value dropped to 18.29.

In another application, AEROFLUID Group provided our VEU-F to remove varnish from a lubrication system of a steam turbine, located in a coal power plant, also in Thailand.

The oil tank size was 32,000 litres and the initial MPC was 40. This result clearly showed that deposits were forming in the system, and they were causing the following problems:

  • valve malfunction
  • the working life of the valves, pumps, and oils was reduced
  • heat transfer hindered in coolers
  • filter elements clogged

The use of HYDAC’s VEU-F made it possible to reduce varnish efficiently, and, in a result of that, the annual oil consumption has decreased by 60%, from 3,200 L to 1,280 L; it’s a saving of 1,920 L per year.

In terms of operating costs, it’s estimated that the plant had saved $400.000 Thai baht (local currency) per year, which is approximately A$17,000 per year, considering the plant had only one single downtime.

Other benefits:

  • reduction of varnish/deposits in the system
  • no malfunction in valves
  • extension of oil the service life
  • no system downtime caused by the oil

The unit can also be used in other industries, such as forming machines and presses, machine tools, hydraulic presses, and injection molding machines.

For more information on HYDAC’s VEU-F click here.