Where to Look For Energy Saving Opportunities

The continuous blowdown from any steam-generating equipment has the potential for energy savings whether it is a fired boiler or waste-heat-steam generator. The following items should be carefully considered to maximize savings:

1. Reduce blowdown (BD) by adjustment of the blow-down valve such that the controlling water impurity is held at the maximum allowable level.

2. Maintain blowdown continuously at the minimum acceptable level. This may be achieved by frequent manual adjustments or by the installation of automatic blowdown controls. At current fuel costs, automatic blowdown controls often prove to be economical.

3. Minimize the amount of blowdown required by:

a. Recovering more clean condensate, which reduces the concentration of impurities coming into the boiler.

b. Establishing a higher allowable drum solids level than is currently recommended by ABMA standards (see below). This must be done only on recommendation from a reputable water treatment consultant and must be followed up with lab tests for steam purity.

c. Selecting the raw-water treatment system which has the largest effect on reducing makeup water impurities. This is generally considered applicable only to grass-roots or revamp projects.

4. Recover heat from the hot blowdown water. This is typically accomplished by flashing the water to a low pressure. This produces low-pressure steam (for utilization in an existing steam header) and hot water which may be used to preheat boiler makeup water.

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