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Posted by Bob D. on June 28, 2010 at 15:34:34:
In Reply to: which boiler? steam boiler or hot water boiler? posted by Erwin budiman on June 24, 2010 at 11:30:42:
Do you mean that you need to heat 600 GPH (10 GPM) in a potable water situation, for human consumption? If so, there's a bit more to consider than just what's "cheapest". Assuming that your product is for human consuption, sanitary considerations would typically prevent you from using a hot water boiler directly (corrosion and scaling concerns would be pretty big also). Usually (and there are always exceptions) there has to be a great deal of protection for the heated, potable, fluid. In many cases, a "regular" low pressure steam boiler could supply a "double wall" shell & tube heat exchanger - keeping the process fluid well protected from the steam heating medium, which may (should) have chemical treatments to ensure reasonable service life for the steam boiler and auxiliaries. Some places find it "cheaper" in the bigger picture (staffing, fuel, maintenance, footprint, etc.) to use an electric heater specifically designed for potable processes. These are available from many sources.
If you don't have to worry about sanitation, you still might want to consider a heat exchanger system of some type, since "once through" water heating in a water boiler is pretty hard on most materials and surfaces due to high oxygen levels, minerals, and other nasty stuff that tends to show up during heating.
Bottom line - I'd recommend you do a little more leg work, identify any regulatory (sanitary) requirements, and maybe contact some vendors or local engineers. Keep the fuel preference in the background until you/we know more.