How to calculate heat loss due to moisture present in fuel?

Calculating % heat loss due to moisture present in fuel to determine the boiler efficiency.

% Loss Due to Moisture

The percentage loss of heat due to moisture present in the fuel is one of the factor to determine the efficiency of the boiler. The moisture enters the boiler along with the fuel leaves the chamber as a superheated vapour. The moisture loss is calculated using the below formula.

Formula:
L₃ = ( M x {584 + C_p(T_f - T_a)} / GCV of Fuel ) x 100
Where,
M = Kg of moisture in fuel in 1 kg basis
C_p = Specific heat of superheated steam in kCal/kg^oC
T_f = Fuel gas temperature in ^oC
T_a = Ambient temperature in ^oC
584 = Latent heat corresponding to partial pressure of water vapour.
GCV 0f Fuel = Gross Calorific Value of Fuel

Let us consider an example, on how to calculate the percentage loss of moisture present in the fuel with the given values.
Step 1: Given that,
Moisture in fuel in 1 kg basis = 0.015 kg
Specific heat of superheated steam = 0.45 kCal/kg^oC
Fuel gas in temperature = 250 ^oC
Ambient temperature =28 ^oC
GCV of fuel = 13000

Step 2: Applying the values in the formula,
L₃ = ( M x {584 + C_p(T_f - T_a)} / GCV of Fuel ) x 100
L₃ = ( 0.015 x {584 + 0.45(250 - 28)} / 13000 ) x 100
L₃ = 0.0789 %

Result : % Heat Loss Due to Moisture Present in the Fuel = L₃ = 0.0789 %

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