PURPOSE BUILT BIO-FUEL BOILER
Energy For Industry (EFI) and Silver Fern Farms Ltd undertook this major project to install a new, purpose-built, 8.5MW bio-fuel boiler at Silver Fern Farms’ largest meat processing plant, Finegand, near Balclutha. The project commenced on 29 June 2007 and commissioning was completed on 24 June 2008.
TECHNICAL INNOVATION
This project has a very high level of technical innovation and is centred on the use, for the first time in New Zealand, of small scale bubbling fluidised bed (BFB) boiler technology that was specifically designed to burn difficult fuels. Additionally, this project is the first in New Zealand to use meat processing waste water treatment plant (WWTP) sludges as a fuel that provides a material net positive energy input [as opposed to incineration of waste sludges]. This was achieved economically by coagulating the sludge using saturated steam injection and decanting to produce dewatered sludge at about 45-50% moisture.
Despite the specialised nature of this project, EFI was careful to ensure the general approach could be replicated at other meat processing sites, and potentially, for other problematic sludges or bio-solids.
As a technically innovative renewable and waste-to-energy project the development of the Finegand BFB boiler plant scheme demonstrates EFI’s commitment to implementing energy projects with positive environmental outcomes. Achieving CEMARS TM certification is another step in EFI’s commitment to work with our partners to measure, manage and reduce emissions and target developments in biomass and waste to energy conversion projects.
SIGNIFICANT SOLUTIONS AND OUTCOMES
The new plant allowed Silver Fern Farms to retire a 46 year old coal-fired boiler, which has markedly reduced emissions of CO2, fine ash particulate and sulphur dioxide.
For Silver Fern Farms the project is an essential part of their drive to reduce energy consumption and related costs, lower emissions and improve energy efficiencies. It is an ideal fit with SILVER FERN Farms’ marketing strategy, which includes the bi-line “natural and carbon conscious”.
It has also mitigated a range of RMA compliance issues - particularly sludge composting disposal and air discharge consent requirements - and it has allowed Silver Fern Farms to modernise its boiler plant and avoid incurring extensive capital outlays on large land areas required for the alternative composting operation.
The plant also includes a wood residue fuel reception, day bin and feed system, a sludge fuel day bin and feed system and a flue gas baghouse. The baghouse filters particulate out of the exhaust gases to achieve a particulate (PM10) content of less than 50 mg/m³ in accordance with current industry best practice standards.
The primary purpose of the new boiler plant is to dispose of sludge from the site’s WWTP. The dewatered sludge fuel is supplemented with imported wood residues. The volume of wood residues required for the boiler operation is very similar to that which would have been needed for composting operation (around 9,000t/y). Sawdust is the preferred wood residue for composting; while a wider variety of wood residues are potentially suitable for boiler fuel. As a result the project reduced the wood residues supply risk.
PARTNERING ARRANGEMENT
EFI developed and fully funded the project under a BOO agreement (build, own and operate) which will continue for 15 years. Under the partnership, Energy For Industry met the costs of developing, building and commissioning the BFB boiler plant. As the plant owner, Energy For Industry is also responsible for the overall management of the boiler operation, including full asset management and ensuring plant optimisation to agreed performance standards. Silver Fern Farms operates the boiler on a day to day basis as part of the 15 year agreement with EFI.
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