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Boiler Feedwater Equipment
 Boiler feedwater usually contains two harmful dissolved gasses: Oxygen and Carbon Dioxide. If the dissolved gasses are not removed before entering the boiler, they will be liberated by heat and may cause severe corrosion in the boiler, steam lines, condensate lines, and heat transfer equipment, which can prove to be very costly. The dissolved oxygen and carbon dioxide can be removed with chemicals. Depending on the overall system, it may not be practical to chemically remove the dissolved oxygen and carbon dioxide from the feedwater. In these cases, a deaerator should be installed. Because the deaerator mechanically removes dissolves oxygen and carbon dioxide, the amount of chemicals required could be reduced. DeaeratorsThe deaerator is a pressurized ASME tank and may be the largest piece of auxiliary equipment in the boiler room. A deaerator is designed to heat water to the temperature of saturated steam at the pressure within the deaerator. A deaerator provides an effective means for recovery of heat from exhaust or flash steam, provides a location for returning condensate and accepts condensate first to reduce excessive make-up water. There are three types of deaerators available. The tray type is normally used in large utility plants. Applications that use a deaerator with a packaged boiler typically use a packed column (see Figure 1-20) or spray type (see Figure 1-21) deaerator. Feed SystemsIf plant conditions do not warrant the use of a deaerator, in most cases, a Packaged Feed System (See Figure 1-22) is used. The packaged feed system is an atmospheric tank that can heat feedwater to a maximum of 210 ° F. Because they are atmospheric tanks, they are equipped with an epoxy lining or made from galvanized steel. The packaged feed system heats the feedwater and reduces the amount of dissolved oxygen and carbon dioxide in the feedwater. However, it’s not as efficient as a deaerator and, therefore, more chemicals will be required to protect the overall system. There are many additional pieces of equipment available to remove impurities in the make-up water before it enters the boiler and system. The type of equipment required is determined by a water analysis. This equipment can be classified as pre-treatment equipment. Surge TanksA surge tank could be used under the following conditions: If there are intermittent peak loads of condensate that can exceed the surge capacity of the deaerator - varying pressures or temperatures in condensate - gravity or pumped condensate that have insufficient pressure to enter the deaerator on their own (see Figure 1-23). Surge tanks are atmospheric and accept condensate and make-up water before it goes to the deaerator. Surge tanks can be lined with an epoxy coating to prevent corrosion. The condensate and make-up water mix into a blend temperature as determined by the percentage of each. Back to General Accessory Equipment | Back to Boiler Descriptions Holman Boiler Works has five locations serving Texas and the Southwest: |
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