Many communities across Canada and the USA have chosen to embrace Blue Flame technology to lower their heating costs and reduce their impact on the environment. Agricultural residue, forest residue and by products wood processing plant and from pulp and paper mills are all cost effective ways to heat sustainably.
Central Heating System
The term District Heating system refers to central system dedicated to the generation and distribution of heat. The heat is distributed to a district heating system where all consumers (industrial, commercial or residential), have the opportunities of utilizing the heat energy available to them. The use of biomass (primarily wood chips, wood pellets, MSW or agricultural residue) at district heating plants has increased significantly since the first systems came into operation.
Many communities across Canada and the USA have chosen to embrace Blue Flame Stoker™ technology to lower their heating costs and reduce their impact on the environment.
Solid fuel biomass combustion systems used in district heating system are more complex than fossil fuel combustion systems and generally require additional components beyond the simple combustor/boiler system. The district heating system components must be carefully integrated to ensure successful, trouble-free operation.
Although not used in all systems, the main district heating system components generally include:
- biomass fuel receiving;
- biomass fuel storage;
- fuel transfer to the combustion system;
- combustion chamber – stoker;
- heat exchanger – boiler;
- ash removal and storage;
- exhaust system with fly ash collection and exhaust stack;
- instrumentation, controls and safety systems;
- backup with a conventional fuel system; and
- heat distribution network – hot water or steam piping.
District heat is transmitted from central heating plants to customers as hot water (or steam) in a closed network consisting of two pipes (supply and return pipes). District heating pipes are laid in the ground, usually at a depth of 4 to 6 feet. The pipes have thermal insulation that prevents heat losses. Various types of piping systems are used for heat distribution. Steal piping has been used by contractors for many years but other types of piping (fibreglass and Pex) are becoming more popular in recent years.
On an average, heat losses in the distribution network account for less than 3 per cent of the energy transmitted in the pipes.
The water circulating in the pipes releases its heat to customers via heat exchangers, hot water coils or in-floor heating configuration. The return pipe conveys the water back to the central heating boiler plant for reheating. The temperature of return water from customers to the biomass boiler ranges between 15 and 30 °F.
Customers receive the district heat in the designated rooms, which includes the heat exchangers for heating and service water, control devices, pumps, expansion and safety equipment.
This project was set out to demonstrate the viability of linking up the central hot water boiler system with number of new and existing buildings in the centre of a community. A network of underground insulated fiberglass pipes was used to link up the hot water boiler and heating systems in the industrial manufacturing facility, school, church, eight residential buildings, broiler barn, chicken barn and hog barn. The primary circuit is a 180ºF temperature water (160ºF return), with constant flow, and medium pressure (20 Psig) system.
The fibreglass pipe is suitable for use at temperatures of up to 210ºF and pressures of up to 150 Psig. The selected pipe is oxygen diffusion-proof. The insulating material is a closed cell non-absorbent foam with densities over 2 Lbs.
District energy plants can be designed to produce not only energy for heating and cooling, but also electrical power. This is called combined heat and power, or CHP. CHP plants are able to get more usable energy out of the input fuel than a plant that only produces electricity.