Introduction
John Thompson was contracted by Unilever Ghana Ltd to design, install and commission a biomass boiler to produce steam for their factory in Tema, Ghana. The boiler was designed to burn various types of biomass fuels. The project was successfully completed in August 2018.
The boiler plant consists of the following equipment:
- Europac TU1050 packaged boiler.
- Triumph chaingrate biomass stoker.
- H-fin economiser.
- High efficiency multicyclone grit
- Bag filter.
The boiler was fitted with various enhancements to aid the combustion of biomass and to comply with the Air Emissions Act. These include a chaingrate stoker with an extended ignition arch which optimises biomass combustion, a bottom primary air (BPA) fan, a side secondary air (SSA) fan and a combustion air heater. An economiser was fitted to increase the overall boiler efficiency.
The primary fuel used since commissioning has been palm kernel shells (PKS). PKS are the shell fractions left after the nut has been removed for crushing in a palm oil mill.
The boiler has performed extremely well operating on PKS for the past three years.
Trials on alternative biomass fuels
In March 2021 Unilever requested John Thompson to conduct trials on alternative biomass fuels available in Ghana to diversify their fuel supply chain.
The biomass market has been growing exponentially in the last couple of years and these tests offered John Thompson the ideal opportunity to test its products and evaluate the performance thereof in actual operating conditions.
Test data from operational plants is critical for John Thompson to validate that the boilers and ancillary equipment offered to our clients are the best engineered solutions.
Test parameters
The testing took place at the Unilever factory in Tema, Ghana, over a period of approximately two weeks in August 2021.
It involved operating the boiler on the most popular biomass fuels available in West Africa, optimising combustion settings and collecting combustion and emissions data. The fuel storage and feeding system was also monitored during the testing.
The combustion tests were conducted by two John Thompson engineers and the emissions sampling was done by specialist emissions sampling scientists from South Africa.
The following fuels were tested:
- Palm kernel shells.
- Wood pellets.
- Cashew nut shells.
- Cacao shells.
Test project’s benefits
Valuable data was collected, enabling John Thompson to better understand the performance of their equipment under normal operating conditions with different biomass fuels. The data and expertise gained from these tests enables John Thompson to:
- Evaluate the combustion characteristics and air requirements of each fuel.
- Evaluate the fouling characteristics of each fuel.
- Validate the theoretical designs with actual data to improve design accuracy.
- Better advise their clients on the capabilities of their equipment.
- Gain valuable sales data to present to prospective clients.
By Rudolf Marais
Design Engineer - Package Boilers
John Thompson
