Presentation on theme: "September 2010 1 Wood to Warmth – Heat Networks Michael Beech TV Energy."— Presentation transcript:
September Wood to Warmth – Heat Networks Michael Beech TV Energy
September Heat Networks Biomass boilers are often combined with heat networks Heat network – Central boiler supplying heat through a network of pre- insulated flow and return pipes, Generally run below ground in a trench ~0.8m down, Allows single biomass boiler to provide heat to a number of buildings, often via individual heat exchangers. Often referred to as district heating – widely used in Austria and Finland.
September Heat Networks
September Heat Networks District heating system often essential to allow introduction of biomass boiler to a site, because: Improved use of space – central boiler plant replaces individual boilers in each building/ unit Single fuel store/ delivery point, lower fixed operational costs vs. many individual boilers More efficient use of system capacity serving diversity of load profiles – smaller kW boiler than total connected kW Affords strategic planning (load growth, future technology improvements in central plant)
September Heat Networks Capital cost Pipe cost, £50- £200/m, depending on type/ diameter, plus fittings (tees, bends, couplings, etc) Trenching, approx £50 - £400/m depending on size, soft/ hard dig, use of on-site labour/ equipment. Many variables determine final cost. Heat losses 20 – 60W/linear Dependent on soil conductivity, temperature, flow and return water temperature. Distribution losses typically a few % of total annual heat delivered How far to connect? Max. 2m pipe (F&R) per kW of connected load as a guide
September Heat Networks % Pumping losses (electricity) Many variables, primarily dependent on resistance in the network. Water flow and return temperatures, flowrates Keep flow/ return deltaT as high as possible, vary flowrate based on heat demand, lower temperatures = longer pipework life Existing buried services, roads, trees Recommend that survey is done before confirming layout and digging trenches.
September Heat Networks Maintenance Fusion welded pipes should not need manholes for access to joints at tees, elbows. Hard/ soft dig Choose soft dig/ easy to reinstate routes wherever possible to keep costs down. Pipe contamination Very important to keep pipes capped prior to connection to heat source, end users. Contamination difficult to eradicate (Park 25).