A feed water heater is a device used in steam boilers to preheat the water that is used to generate the steam. It is the primary role of the feed water heater to recover the heat from the condensate produced through the condensation of the steam, to reduce the cooling costs for the steam-generating boiler, and to ensure the steady supply of hot feedwater to the boiler.
Feed water heaters come in a variety of different designs, including shell-and-tube, plate type, and plate-and-frame type. The selection of the heater design depends on the specific requirements of the application, such as the desired temperature of the feedwater, its flow rate, and its pressure. A common efficient design is the shell-and-tube heat exchanger.
The feed water heater is typically placed downstream of the steam turbine or a condensing unit, such as a combined heat and power plant. This is done to ensure that the heat contained in the condensate released from the turbine is not wasted but rather put to use by preheating the water entering the boiler. The condensate can also potentially be used to generate more steam at a lower cost.
The feed water heater consists of a tank of hot condensate, a heating coil, a cooling coil, and a temperature control system. During operation, the heating coil is used to heat the water flowing into the heater. This heat is then transferred to the condensate tank through the heating coil, where it is stored and used to preheat the cold water located in the cooling coil. The temperature of the condensate entering the cooling coil is controlled by the temperature control system.
After the water in the condensate tank is preheated, it is sent to the boiler where it is quickly converted into steam. The water that is exiting the boiler heated up significantly, therefore, successive batches of water can be heated without extra energy. This increases the efficiency of the boiler, reducing fuel costs.
The feed water heater can also be used to reduce peak steam demand, hence decreasing the boiler load. This reduces the operational costs associated with the boiler and helps to prevent the boiler from exceeding the safe working limits.
In addition to the efficiency and cost benefits associated with the feed water heater, it also helps to improve the life of the boiler system by reducing the thermal stress due to sudden rise in temperature. The feed water heater allows for a gradual increase and decrease of temperature in the boiler system, resulting in increased reliability.
Given all the benefits that it brings to the boiler system, investing in a feed water heater can be a great way to reduce energy and fuel costs, as well as to improve the efficiency of the system.
