NOTE: Use only TIF heat rejection data for heat recovery calculations, DO NOT USE RULES OF THUMB.
Conversions:
One Boiler HP = 558 BTU/min = 33,475 BTU/hr = 9.8 kW
One Refrigeration Ton = 200 BTU/min = 12,000 BTU/hr = 3.5 kW
Recoverable Exhaust Heat:
Heat recovery mufflers economically recover about half the engine exhaust heat. Exhaust exit temperature above 300°F (149°C) discourages condensation in ducting.
Recoverable heat is obtained from the engine manufacturers but can be estimated by:
Q = CpM (T1 - T2)
Where:
Q = Recoverable Heat (Btu/h)
Cp = Specific Heat (Btu/lb per °F)
T1 = Exhaust Gas Stack Temperature °F
T2 = Exhaust Gas Exit Temperature °F (300°F Minimum)
M = Exhaust Mass Flow (lb/h)
or
Q = CpM (T1 - T2)
Where:
Q = KJ/h
Cp = Diesel Engines - 1.081 KJ/kg per °C
M = Exhaust Mass Flow (kg/h)
Enthalpy Table:
Ebullient and Solid Water Cooled Engines:
Make-up Water Characteristics (max concentrations):
Iron 0.1 ppm
Copper 0.05 ppm
Total hardness 0.3 ppm as CaCO3
Feed Water Characteristics (max concentrations):
Silica concentration 150 ppm as Si02
Total Alkalinity 700 ppm as calcium CaCO3
Specific Conductance 3500 micro ohm per centimeter
Total Suspended Solids 10 ppm
Feed Water Chemical Treatment Program:
1. Maintain oxygen scavenger to remove oxygen from the feed water with sufficient reserve to remove all oxygen from the water.
2. Maintain 200 to 400 ppm as CaCO3 equivalent of hydroxide alkalinity in the feed water. The reserve alkalinity prevents corrosion and causes precipitates of iron and silica in a form that can be removed by blow down.
3. A blend of dispersants to adequately condition and suspend the precipitated solids in the water. The dispersants keep the solids suspended until they are removed during blow down.
4. Appropriate treatment of the stream to provide condensate returning to the boiler that meets the feed water specifications.