Economizer and Recuperator Systems
EKONOMİZER
Economizers are devices that provide fuel saving and increase boiler efficiency by taking advantage the waste heat of flue gases, heating the feed water in Steam Boilers, heating the system water in hot and superheated water boilers.
5% to 10% increase in efficiency in economizer equipped boilers is possible by reducing the temperature of flue gases to the level of operating conditions.
The payback amortization for an efficient economizer is in a short span of time as 3 to 6 months depending on intended use, system capacity and operation time.
Condensation temperatures vary according to the type of fuel. When the economizer gas outlet temperature decreases below a certain temperature, acid gases that may cause corrosion will begin to condense. For this reason, emission type and temperature values play an important role in economizer design.
REKÜPERATÖR
The recuperator is an energy recovery system that provides air-to-air heat transfer. In other words, it is the equipment that allows the relatively high heat energy contained in the waste flue gas to pass to a cooler air. They are systems that provide high fuel savings, generally used for heating the burner front air. By reducing the flue gas temperature in the recuperators to operating conditions, an efficiency of approximately 4% to 8% is obtained.
Condensation temperatures vary according to the type of fuel. As in the economiser, when the recuperator gas outlet temperature decreases below a certain temperature, acid gases that may cause corrosion will begin to condense. For this reason, emission type and temperature values play an important role in recuperator design.
CALCULATION
Q = B *Vg*Δt*Cp
m = B*Vg
Q : kcal / h Quantity of Heat Gained in the Economiser
m : Nm³ / h Flow Rate of Flue Gas
B : Nm³ / h Quantity of Fuel Used
Cp : Kcal / Nm³°C Specific Heat of Flue Gas
Vg : Nm³ / Kg Specific Amount of Flue Gas
Δtm : °C Temperature Difference
Amount of Fuel Saving from Recovered Energy:
B1=Q / (Hu*nk)
B1 : Nm³ / h Quantity of Fuel Saving
Q : kcal / h Quantity of Heat Recovered in Economiser
Hu : Kcal / Nm³ Lower Heating Value of Fuel
nk : % Efficiency
Sample Calculation:
Q : 200.000 kcal / h Based on Measurements fort he economiser of a 200.000 kCal / h gas-fired boiler
nk : %90 Boiler Efficiency
Hu : 8250 Kcal / Nm³ Lower Heating Value of Natural Gas
Fuel Saving Per Hour for Natural Gas:
B=Q / (Hu*nk)=200000 / (8250*0.90)=26,93 Nm³ / h Natural Gas Saving
Annual Fuel Saving in Economiser System:
26,93 Nm³/h*16h/Day * 300 Days = 129.264 Nm³ / Year
Annual Fuel Saving (TL):
Fuel Unit Price : 6,3 TL / Nm³ (2022)
129.2640 Nm³ / Year * 6,3 TL / Nm³ = 814.363 TL / Year