February 2019 progress report
Published: 31 Jan 2019
The last few months have seen progress made across the whole site. Much of the work has focused on completing the electrical cabling and equipment installation, completing the mechanical equipment along with checks, pre-commissioning and preparation for commissioning of the facilities.
Within the anaerobic digester (AD) area, wet pre-commissioning has continued. This is the process of circulating water through the system to check all the valves and pumps work as they should. Alongside this, work has continued on the cabling and electrical works as well as completing and checking the control rooms and panels. The introduction of waste to start hot commissioning is expected to happen in early March.
At the point where waste is introduced, the digester tanks will also be 'seeded'. This is the process of introducing micro-organisms to the tanks. These will break down the food waste to produce the biogas. Once food waste is introduced, the process will be continuous as food waste is needed to 'feed' the micro-organisms in the digester tanks.
With the exception of the combined heat and power engine, which was commissioned last year, the rest of the AD process will be commissioned simultaneously.
In the gasification facility, a number of mechanical systems have now been completed such as the compressed air pipework and the odour control systems. These are essential before the site can start hot commissioning and accepting waste. The main access doors to the gasification tipping hall have also been installed.
The gasification facility will be commissioned in two stages – first the pre-treatment, and then the gasification unit itself, with the boiler and turbine and generator. The introduction of waste for the pre-treatment equipment is expected to start this month.
The pre-treatment equipment is where the black bag waste collected from the kerbside is sorted and processed to convert it into refuse-derived fuel (RDF). The sorting involves various processes to separate the waste by size to remove large items, plus any rubble and hardcore that cannot go into the gasification unit. The processing also uses an eddy-current separator and magnets to separate and collect any metals for recycling.
Once sorted, the remaining waste is shredded to turn it into refuse-derived fuel. At this stage, during commissioning, the RDF will then be transported off site to another processing facility, until it is required to commission the gasification unit.
In March, in preparation for commissioning of the gasification unit, we will start steam blowing. This is the process of forcing steam through the system to clean everything out and remove any construction debris. As the name suggests, this will result in steam being emitted, which will be visible. Shortly after this, we expect to start commissioning the gasification unit itself, which will also be visible as emissions will come from the stack.
Across the site
Across the rest of the site, the administration building is now complete with some desks and furniture in place ready for the team to move in. The cedar cladding on the outside of the building is almost complete and should be finished soon. Work to screen the landscaping bund has finished and we are now waiting for the final decision on the planning application for the layout of this area, before we can proceed and complete the works.