9.1 Plant Heat Rate & Calculation

What is Heat Rate?

The amount of Heat Energy required for getting unit amount of electrical energy.

·                Unit of HR = Kcal/KWh

Theoretical there are two types of Heat rate:

·                Gross Heat Rate.( Gross power is taken)

·                Net Heat Rate. (Net power is Taken)

Gross Heat Rate:

The heat energy in Kcal input required to generate one KWh of electrical energy at generator terminal.

 

Gross Heat rate of a unit =	Gross Turbine Heat Rate (Kcal/Kwh)	x 100
	Boiler Efficiency (%)

 

Where,

Gross Turbine Heat Rate =	Heat input to Turbine (Kcal)
	Generation at Generator terminal

Net Heat Rate (NHR)

The heat energy in Kcal, input to a generating unit to deliver one KWh at the switchyard.

 

=	Gross Heat Rate (Kcal/KWh)	x 100
	(100 – APC in %)

 

The monthly / yearly average Gross Heat Rate shall be calculated by weighted average as per the following formula.

 

=	Σ GHR X KWh
	Σ KWh

 

Where,

GHR = Gross Heat Rate (Kcal/KWh) of the particular day

KWh = Generation (KWh) of the particular day

 

Plant Heat Rate: Ratio of total Heat input to the plant as a fuel to Power Generation from the Plant.

·                Plant Heat Rate = (NCV X Mass of Fuel) / Power Generation

= Turbine Heat Rate / (Boiler efficiency/100)

Turbine Heat Rate: Ratio of total Heat input to the Turbine in Steam to Power Generation. Turbine Heat Rate = (Mass of I/L Steam X Cp X Delta H) / Power Generation

Delta H = (Main Steam Enthalpy – FW Enthalpy)