Which Reciprocating Grate Bar Type: S-Shaped, Heavy Wide or T-Shaped
The section of a reciprocating grate bar is not arbitrary: it decides where the air leaves, how the fuel travels down the grate and how much fine material falls through. Three types are in common use today: the S-shaped bar, the heavy wide bar and the T-shaped bar. Before choosing, look at three things: the particle size of the fuel, its moisture content, and the bulk density of the fuel bed.
S-shaped bar: tight air slots, little fall-through
The S-shaped bar is the standard choice. It is strong enough, its air slots are closely spaced, and the outlet usually sits at the bottom of the bar end, so air enters the fuel bed fairly evenly and little fine material drops through the gaps.
It works for coal and for ordinary biomass, and it is the easiest type to match when a replacement is needed. On a grate with a moderate bed depth and no very coarse particles, it is enough.
Heavy wide bar: coarse, wet and dense fuel
The heavy wide bar is stronger and carries air holes on its surface. It suits fuel with coarser particles, higher moisture and higher bulk density, and it resists deformation when the bed is deep and the stirring resistance is high.
The other side of that is weight. For very fine, low-moisture material it is on the heavy side: air goes straight up through the surface holes and fine particles are easily lifted, so the S-shaped bar fits better in that case.
T-shaped bar: square slot on a square beam, for wide coal-fired grates
The T-shaped bar has a square slot and mounts on a square cross beam, which gives the assembly good rigidity. It is mostly used on large coal-fired reciprocating grates and fits grates with a wide furnace better, because a long span demands more bending strength from both beam and bar, and a square fit holds up better than a round one.
Where the boiler burns coal and the furnace is wide, this type usually suits better than the other two; on a biomass grate of moderate width there is no need for it.
How to decide
A workable order is this. Start with particle size and moisture: fine and dry points to the S-shaped bar, coarse, wet and dense points to the heavy wide bar. Then look at furnace width and whether the fuel is coal: wide and coal-fired points to the T-shaped bar. Finally confirm against the grate drawing or the measured dimensions of the old part.
The three types can also be mixed on one grate by zone, for example heavy wide bars in the main combustion zone and S-shaped bars elsewhere.
We supply moving and fixed grate bars for reciprocating grates along with the matching parts, dispatched from a partner factory, and we can check the bar type together with your grate model and fuel.
