Combustion & Furnace Design
The fixed grate burning system is relatively simple, yet functional. The system features pinhole grates which allow primary air to be evenly introduced, at speed, into the furnace. The primary method of cooling a fixed grate system is via air brought in from a force draught fan. In addition, the grates can be water-cooled to minimise excessive heat on the grate surface thus providing protection from premature failure. Reductions in overall maintenance costs can be achieved as fixed grates minimise failures in bar operations through overheating and wear & tear as there are less moving parts.
Boilermech’s air or semi-water cooled reciprocating grates are designed to combust high-moisture biomass fuels while limiting emissions output. Incoming biomass fuel is regulated through a spreader feeder which distributes the fuel evenly across the grate surface. The burning biomass is then conveyed forward in stages through the firing chamber by the grate’s reciprocating action. This reciprocating grate bar movement tumbles and mixes the refuse and primary air uniformly to ensure effective combustion directly on the grate. The reciprocating action also discharges residue/ash from the back end of the boiler to the boiler front to be discharged by means of a submerged ash conveyor.
Vibrating grates are effective in the combustion of biomass. The vibrating movement evenly distributes the fuel across the grate allowing better air-fuel mixture which enhances combustion. The vibrating grate allows complete combustion of the fuel, even high moisture and high ash fuel. The heavy-duty, heat-resisting cast-iron machinery allows plant operators to combine high-efficiency firing with minimal emission output. Moreover, its durable structure enables prolonged periods of operation without the need to shut down for maintenance or extended grate cleaning. They are water cooled which enhances the lifespan of the grate while also minimising clinker formations on the grate.
The vibrating grate has pin holed design to provide an even distribution of air under the fuel bed, while operators can regulate ash bed thickness as well as adjust the unit’s vibrating frequency simply by means of a wheel mechanism. The other key advantage of a vibrating grate is that has low maintenance costs due to its low number of moving parts.
Superheaters convert saturated steam or wet steam into dry steam used for power generation or plant processes. Boilermech designs and manufactures muti-loop alloy tubes for high superheat steam. Our design expertise in constructing proper tube steam distribution channels mitigates steam starvation, while automatic steam venting systems are in place to maintain the minimum required steam flow in the tubes.
Conventional Water Tubes & Tiles
Arguably the most common and simple combustion chamber design is the use of wide-spaced water wall tubes enclosed with flat tiles. The boiler design lends itself to typical fuel, firing wood, biomass, as well as other fuels. Conventional tube and tile furnaces maintain their heat after shutdown making them suitable for plants which regularly require start-stop operations.
Boilermech’s membrane wall furnaces are usually coupled with vibrating water-cooled grate stokers to provide our combustion chambers with highly efficient performance standards. The gas tight design of the membrane wall promotes greater heat absorption, while the water cooled furnace chamber eliminates slagging on the furnace surface.
The membrane wall furnace also leads to lower exiting gas temperatures which minimise fouling on the heating tube surface. Membrane wall furnaces eliminate problems associated with refractory failure, leading to significant maintenance cost savings. Another key advantage is that by utilising a membrane wall design, the entire furnace operates at a uniform temperature, ensuring that all combustible components are reacted and differential expansion is minimal.