Boiler Feedwater Make-up Pre-heating using Solar Collectors
The customer uses a furnace oil boiler and therefore, their cost of steam is significantly high. However, they recover much of the condensate and had boiler feedwater that needed to be heated from the ambient temperature. Generation of steam using Parabolic Trough Collectors or Scheffler Collectors was ruled out due to cost factor and inconsistency in ability to maintain the required pressure for the process.
A solar water heater farm using Evacuated Tube Collectors (ETC) was designed and implemented to heat the feedwater from 25 deg C to 70 deg C (avg.). ETC collectors were chosen instead of Flat Plate Collectors (FTC) due to the following factors:
a) Lower Cost
b) No scaling issues
c) Ability to use diffuse radiation too for heating the water.
Also, innovative heat exchanger design was used to lower the cost of the solution. Instead of having separate collector farm and a large tank, small 250 LPD solar water heater systems were used to make the entire system modular and scalable.