# How to Calculate Heat Loss Due to Unburnt in Bottom Ash?

Calculating heat loss due to unburnt in bottom ash to determine the efficiency of the boiler.

## % Heat Loss Due to Unburnt in Bottom Ash

The percentage heat loss due to the unburnt in the fly ash is defined as
the ratio of total ash collected divided by the kg of fuel burnt
multiplied by the gross calorific value of bottom ash the whole divided by
gross calorific value of the fuel multiplied by 100. This loss is one of
the factor that affects the efficiency of the boiler.

**Formula:**

**L**_{7} = {[(Total Ash Collected / kg of Fuel Burnt) x GCV of Bottom Ash] / GCV of Fuel} x 100

Let us consider an example on how to calculate the heat loss due to unburnt in bottom ash with the given values.

**Step 1:** Given that,

Total ash collected = 150

Kg of fuel burnt = 1000

GCV of bottom ash = 3000

GCV 0f fuel = 5000

**Step 2:**

Applying the values in the formula,

L_{8} = {[(150 / 1000) x 3000] / 5000} x 100

L_{8} = 9%

**Result:** % Heat Loss Due to Unburnt in Bottom Ash L_{8} = 9%

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