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Pre-Treatment Equipment

Filters (see Figure 1-24) are available to remove free chlorine, some dissolved organics and sediment. They can also remove suspended solids, colloidal matter, sand and iron.

There are carbon filters, multilayered filters, sand or iron filters. There can be lined tanks, ASME code tanks and automatic operation based on a time clock, pressure differential switch or water meter. They can protect such items as water softeners, dealkalizers, and reverse osmosis equipment, etc.

Water Softener

There are many different types of water softening systems available today. No attempt will be made in this section to explain the operation of them all. Probably the most popular and widely used type of water softening method is the sodium zeolite softening process (see Figure 1-25), more commonly referred to as zeolite softening. This type of softening process will remove the calcium and magnesium salts from water and reduce it to zero hardness. Through an ion exchange process, water softeners remove hardness and replace it with highly soluble sodium ions; thus preventing scale buildup on heat transfer surfaces. Removing hardness also reduces the need for chemical treatment used to control scale. A water softener can be single or multiple tank and automatic or manual operation.

The zeolite type of softening process can be used in conjunction with other external or internal treatment processes or equipment for boilers. Other types of equipment that could be in a system are:

1. Dealkalizer - Employ an ion exchange to reduce Bicarbonate Alkalinity. It replaces bicarbonate, sulfate, nitrate, and silica with chloride ions.
2. Reverse Osmosis Units - This type of unit is used to reduce dissolved solids in make-up water. The unit uses a semi-permeable membrane that allows water to flow through it and at the same time restricts the flow of dissolved solids. The dissolved solids remain in solution and are carried out of the unit to waste.

While the amount of chemicals added to a boiler and system can be reduced with the use of pre-treatment equipment, chemicals still have to be added. Chemicals are normally added with the use of chemical feeders.

Note: Contrary to common belief, hot water boilers often require treatment to a limited degree.

Chemical Feeders

There are several different methods that can be utilized to feed chemicals into a boiler. However, there are two basic types and most chemical feed equipment can be classed in one or the other.

First and simplest is the pot type Manual Shot Feeder. Pot type feeders are frequently installed in small boiler plants, on the discharge side of the boiler feed pump. The feeder is convenient and economical for the injection of precipitating chemicals in closed loop or low make-up systems.

The second group of chemical feeders is the Chemical Feed System (see Figure 1-26) and Metering Pumps (see Figure 1-27). These systems provide for feeding chemicals into a boiler at a predetermined and controlled rate.

Chemicals for oxygen removal, pH adjustment or any of the surface active organic and inorganic chemicals for prevention of deposits or corrosion in distribution lines, would normally be added to the system with this type of arrangement.

Depending upon the degree of sophistication, this type of system could includes a chemical tank, pump, complement of valves, piping, etc., plus some type of control mechanism, timer or meter.

Holman Boiler Works has five locations serving Texas and the Southwest:
Dallas / Fort Worth – Houston – Corpus Christi – San Antonio / Austin – McAllen