Ideas for money-saving steam system upgrades
Why worry now about efficiency?
It makes sense in today’s economy more than ever to save steam and cut energy consumption. Improving steam system efficiency need not be a major investment. Modest measures taken whenever budgets allow can still yield impressive results. Any of the following upgrades will boost performance and achieve a short payback with real cost savings.
Return of condensate
Returning condensate to the boiler can save thousands of dollars per year. Condensate contains about 20% of the energy in the steam from which it came. Returning water to the boiler feedtank recovers about half this energy, with the other half being contained in flash steam that can be retrieved by a flash steam vessel or pressurized condensate return system.
As well as saving energy, condensate return saves water treatment chemical costs. Effluent changes may also be reduced because less water is discharged to drain.
Blowdown and heat recovery
Save costs by improving the boiler water blowdown system, which draws off water to control boiler contamination. Many boilerhouses use blowdown valves, manually opened at regular intervals, with any water removed being dumped to drain.
An automatic total dissolved solids (TDS) blowdown controller is a better option. Continuously monitoring TDS build-up in the boiler, the controller opens the blowdown valve as required to reduce contamination, therefore minimizing energy loss.
Greater efficiency is also achieved by recovering the heat from the blowdown water, as it flashes to steam. Flash steam can be separated in a flash vessel and injected into the boiler feedtank saving both energy and water.
Feedtank heating and deaeration
Less fuel is needed to produce steam from hot feedwater. Using return condensate to raise the feedwater temperature by 10.8 F gives a fuel saving of 1%. Ideally, feedwater should be maintained at 194 F.
Simply feeding condensate into the top of the feedwater tank can be inefficient. As the condensate falls through the space above water, vapor and energy can be lost and air admitted. A deaerator head solves the problem by mixing condensate, flash steam and cold make-up water as they enter the feedwater tank.
Automatic start-up valve
Manpower can be saved and safety increased by installing an automatic warm-up system. An electrically actuated valve controlled by a timer opens automatically at a pre-set time and at the correct rate to slowly heat up the steam system.
Automatic systems save energy by allowing sections of plant to be shut down when not required, at night or weekends for example.
Automatic bottom boiler blowdown
Manpower, energy and water savings can be achieved by automatic boiler bottom blowdown to remove sludge from the boiler. This eliminates the excessive blowdown that often results when a boiler attendant manually opens the blowdown valve.
Measuring energy consumption gives an important benchmark when working to improve energy efficiency. Steam meters can be used to detect excessive consumption or to charge energy costs to individual departments, thereby encouraging sound energy management.
Money-saving upgrades at a glance
Content provided by Spirax Sarco, originally published in Steam News Magazine.