Date: August 2020
Acoustic Cleaner Model: 1 x Q1
BHSL utilise a combustion-gas-to-air heat exchanger at the downstream section of their poultry manure boiler system to pre-heat combustion air in order to improve the efficiency of the fluidised bed furnace design. Due to the high ash content of the fuels they combust, BHSL have seen deposits on to their heat exchanger, reducing efficiencies and in some cases causing blockages of the gas pass.
Offline cleaning has to be undertaken to clear any build-up. BHSL has implemented mechanical contact cleaning, and soot blower cleaning of the heat exchanger but has recently begun investigating acoustic cleaning of their system. The Q1 acoustic horn was initially trialled on an existing plant in Scotland with very positive results and was subsequently incorporated into the design of new systems, the most recent installation is in Hereford, commissioned in August 2020. The acoustic horn option is seen as an excellent choice in place of mechanical contact cleaning and soot blower cleaning. It is non-contact and utilised less compressed air reducing the chance of mechanical damage and the parasitic load.
With the Acoustic horn installed, BHSL has been able to maintain the required inlet and outlet temperatures on both heat exchanger passes. The acoustic horn system has kept the exchanger clean, removed the need for any other automatic cleaning systems and reduced offline cleaning to a minimum. The horn is set to sound for 10 seconds every number of hours, within a daytime period, 8am to 6pm. This has been sufficient to keep the surface of the heat exchanger adequately clean.
The above shows the installed Q1 horn with the acoustic enclosure removed. Below shows a cleaned and dirty heat exchanger, indicating the issue of lost efficiency they were dealing with.
The graph below shows the inlet and outlet combustion gas temperature to the heat exchanger. As can be seen, a reduction in outlet temperature and inlet temperature is seen immediately after the horn sounds.
The reduction in inlet temperature also shows that the horn has a positive cleaning effect on heat exchangers upstream.
Reduction in inlet and outlet temperatures to the heat exchanger noted at points 80, 200, 360 & 480 over a 24-hour period. The temperatures can be maintained inside a range with the intermittent sounding of the Acoustic Horn.
