CWM builds latest technology into £40m MSW burning plant

municipal waste incinerators being built by CWM at Billingham. LAWE reports on the £40 million plant

The third of the new generation energy from waste plants is on schedule for operation in Billingham later this year. The municipal solid waste (MSW) burning facility in which Cleveland Waste Management, the single-purpose company set up under a joint venture between Northumbrian Environmental Management and Cleveland County Council, is investing approximately £40 million, will have the capability to deal with 250,000-260,000 tonnes of MSW and commercial waste annually. Thermal capacity will depend, as in any MSW plant, on what constituents there are in the waste stream.

CWM has won a waste management contract dealing with waste disposal which will run for 25 years and will be funded by gate prices plus an NFFO award for power generation. The prices are RPI linked throughout the length of the contract with the only changes allowed being those brought about by external acts such as the Landfill Tax.

There are two waste streams, both capable of incinerating 14 tonnes/hr. One of the provisos of permission to build the plant was that it would only burn municipal waste and that there would be no incineration of hazardous or clinical waste or sludge.

The plant, which is expected to generate in the region of 20MW, is being built on a brownfield site that was formerly part of the ICI Process Plant Park at Billingham near the Tees. It will handle two thirds of the municipal waste produced by the four borough councils of Hartlepool, Stockton, Middlesbrough and Cleveland which formerly constituted the County of Cleveland.

The remaining non-combustible elements of the waste will be recycled or landfilled. Since the old incinerator was closed down last year all the waste has been going to landfill. This was despite efforts by CWM to be allowed to keep the plant going for the relatively short time until the new facility comes on stream in the autumn.

As part of its overall commitment to disposing of the area’s waste CWM is also developing a landfill site at Carlin Howe Farm near Guisborough. Able to take in 100,000m³ per annum and with 14 years’ capacity, the site will be able to accommodate 1.4 million m³ of landfill material over its life.

The decision to develop the landfill site reflected the fact that the former County of Cleveland is densely populated and that there were not many landfill sites available The “proximity principle” for waste disposal was also a factor with county councillors feeling that it was important to dispose of their own waste within the region. CWM, which owns the site, considered that it needed to have that aspect of its business under its control.

The new waste to energy plant on Teesside, which is well on its way to completion on time, will replace the now closed former waste incinerator at Portrac This had been built in 1976 at a main crossroads and was originally proposed as the site of the new facility. However, the planning authority, Teesside Development Corporation, opposed the plan as it was fe that incineration was incompatible with th overall image that it was trying to create to promote regeneration of a previously industrialised corridor of the River Tees.

Following appraisal of 76 alternative locations, the Billingharn site was selected. Potential issues which might have arisen as a result of the proposed waste to energy plant were subject to a specialist analysis during the environmental assessment.

A priority in the architectural design of the project has been to give the building, which fully encloses the process, an acceptable appearance. An impression of the ultimate effect is indicated in the accompanying photographs of the site as construction progressed.

Landscaping, including earth mounding and 6-metre high bund, is also being employed to screen views from the southeast and to minimise the impact of the facility. The landscaping will include trees and shrubs and there will be water features.

On the landfill site special provision is being made for the Great Crested Newt.

Over the planning stages of the project there was considerable consultation with councillors, local interest and resident groups, MPs and MEPs.

The involvement with the community is intended to continue as the plant comes into operation and there will be facilities built-in to allow visitors to see how this modern facility works.

Although the waste to energy plant site had formerly been used for the production of sulphuric acid and cement clinker, dealing with potential contamination did not pose great problems, according to CWM. Where contamination was identified it was disposed of in conjunction with the Environment Agency.

Managing the project

CWM oversees the project through a small management team headed by Director and General Manager Jon Garvey who was in at the inception of the scheme and will be responsible for its operation once the plant has been commissioned later this year. CWM is scheduled to take over on October 1.

Day to day project management of the construction of the plant is carried out for CWM by Turner and Townend, a UK project management practice.

The contractor for the CWM plant comprises a consortium including civil contractor Sir Robert McAlpine in a management contracting role.

The state-of-art technology which will convert waste into energy through incineration is being provided by the Danish waste incineration specialist, V(lund Ecology Systems A/S which is a company of the Italian Ansaldo Group.

V(lund brings an impressive record to the project, having supplied 350 incinerator lines in approximately 200 plants since 1931.

Plant design

V(lund deals with the furnace/boiler and associated grate system. The Danish company says that this means that plant concept, furnace design, grate system, combustion air system and the boiler design are being researched and developed continuously.

While the V(lund plant is based on established design the latest developments have been incorporated in the CWM installation.

In general the design of the V(lund furnace is based on the primary combustion taking place on a movable grate which controls the feeding of the waste through the furnace and where the major part of the necessary combustion air is supplied from the bottom of the grate up through the waste.

The result of designing the furnace according to the co-current principle, says V(lund, where waste and fuel gases move through the furnace in the same direction, is that all released gases and particles are forced through the hottest zone of the furnace and stay long in areas of high temperature. This ensures that clinker burns out at a high temperature and that the burnout of flue gases is completed before they reach the boiler where the temperature level is lower.

The grate design embodies a modular grate design with few, easily replaceable wearing parts. This modular design has movable grate beams with air gaps ensuring the necessary supply of primary air simultaneously, with efficient cooling of the individual parts of the grate.

The grate design makes it possible to dismount and mount the grate components from above during servicing.

The grate construction consists of fixed and movable elements, which in a longitudinal and lifting movement

simultaneously transport the waste forward, level and rearrange it so that ignition, combustion and burnout of all waste components are carried out with the correct supply of combustion air. Any holes formed in the waste layer where burnout is quick are closed by the rearranging movement, V(lund explains.

Main elements

The main features of the Billingham facility are refuse reception, the waste burner, clinker pit and metal recovery; the incinerators, the turbine hall and the stacks. There are three distinct vertical flues in the stack, one for each of the waste streams with the third for stability.

CWM has also constructed a water abstraction plant from the nearby Tees to provide cooling water for incineration and has laid inflow and outflow pipelines to the site.

Gas cleansing

Cleaning of gases and emissions is tackled by a semi-dry system. Gases are drawn through a reactor vessel where lime slurry and activated carbon are injected. Bag filters are also used to remove dust.

Emissions control will be monitored by the Environment Agency who will have access to all the relevant data. Refuse vehicle deliveries will be to a spacious reception hall where loads will be tipped into a bunker. Mechanical handling at the plant is provided by four KCI Carruthers cranes – two waste handling cranes, one clinker and one machine room crane.

IT will be an important aid in running the new plant, from the Sherings weighbridge system for incoming vehicles to computerised control of the plant operations and external and internal CCTV. The external TV is not only for security purposes, it also allows control room staff to monitor what is coming into the plant. Within the plant CCTV will monitor pressure points the boiler, furnace and clinker conveyors. Rolls Royce Industrial Controls is supplying an In-Touch computer system which manages the plant operation.

CWM will have about 40 employees, including management who will be based in new offices contained in the plant at Billingham, and staff operating the MSM facility and the landfill site. All staff will have full facilities and there will be provision for visitors including educational and local groups.

On the question of recycling Mr Garvey said: “We have a disposal contract. We have to deal with whatever is delivered to us. borough councils have recycling obligations which they can either deal with separately or they can involve us.”

Metal is recovered from the incineration process and CWM and other energy from waste operators which are working through the Energy from Waste Assocaiation to explore the possibilities of recycling bottom ash perhaps into building materials.

That positive approach, allied to the architectural treatment given to the look the building itself and the facilities for visitors, should ensure that CWM maintains a good image among the 550,000-plus residents whose waste it handles.

As Jon Garvey pointed out: “The nature of these contracts is that they are very long – term – we are here for 25 years. Therefore it is incumbent on us to become good neighbours and contribute to the local community.”