For air–cooled grate, the main reliance on air flow is to cool the grate slabs. For this reason, the grate slabs should have enough auxiliary slabs to allow the air to scour and cool. The cooling degree of the designed grate is generally considered to be no less than 2~3. When the low calorific value of garbage exceeds 8260kJ/kg, water cooling grate needs to be considered (see Figure 4–16)