The Importance and Use of Boiler Economizer in Industrial Steam Boilers

Boiler Manufacturers throughout the world strive to design and manufacture boilers that are efficient and cost-effective. In a Steam Boiler, steam generation takes place through the burning of fuels that leads to flue gases. Boiler water in steam boilers is heated with flue gases and converted into steam, which is released for the processing operations in industries. After the steam generation, the flue gases leave the boiler.

However, these flue gases contain heat energy which remains unused and results in losses. To overcome this, Boiler Economizer is installed by the steam boiler manufacturers that aids in reducing energy consumption and in preheating boiler feedwater.

A Boiler Economizer is a mechanical device, or in other words, a heat exchanger that facilitates a higher energy-efficient system by capturing enthalpy in fluid systems that are not heated enough to be utilized in operations. Economizer retrieves more useful enthalpy, resultantly increasing the efficiency of the steam boiler. The Boiler Economizer functions on the principle of Heat Transfer. As we know, heat transfer occurs from high temperature to low temperature. In steam boilers, the flue gases exiting the boilers are of high temperature, and the water for preheating is at low temperature. The difference between the temperature of flue gases and water helps in increasing the feedwater temperature with the help of Economizer.

Structure of the Boiler Economizer:

The design of the economizer is kept simple by the boiler manufacturers. The bottom part is a horizontal inlet pipe used for feeding normal temperature water in the steam boiler. Similarly, there is another horizontal outlet pipe located at the top of the economizer for hot water. Both the horizontal pipes at the top and bottom are linked through a series of vertical pipes. The flue gases from the furnace of the boiler pass through these vertical pipes. Boiler economizers contain safety valves for their safe and smooth functioning.

Working of the Economizer in a Steam Boiler:

Flue gases enter the economizer as they exit from the steam boiler. With its finned tubes, the economizer takes over the heat of the flue gases and transfers it to the feed water.

The steam boiler manufacturer designs economizers in such a way that the flue gases transfer the remaining heat to the feed water through the vertical pipe as the water passes through it to enter the top horizontal pipe. That is how the remaining heat of the flue gases is used in heating the feed water before it enters the steam boiler for generating steam. It is important to monitor the ash particles from the flue gases that remain on the surface of the vertical pipes. Overlooking it may result in the formation of soot.

Depending on the process operations, the design of the economizer can be a smoke tube or water tube. In the smoke tube economizer, flue gases are inside the tube, and the water is in the shell, whereas, in the water tube economizer, flue gases are in the shell, and the water is in the tubes.
Generally, the flue gas temperature of high-pressure steam boilers ranges from 400 degrees F to 650 degrees F. This high-temperature exhaust results in energy wastage. Economizers, therefore, help in reducing such heat loss and energy input in the steam boiler.

Types of Economizers:

There are 2 types of Boiler Economizers used in steam boilers. They are Condensing Economizers and Non-Condensing Economizers

Condensing Economizers:

Condensing economizers are further sub-divided into two types, heat exchanger and direct contact. Condensing economizers are designed in a way to adapt the generated corrosive fluids during the process of condensation of the moisture from the flue gas. Condensing economizers absorb more heat and increase the overall efficiency of the boiler by 10% to 15%

Non-Condensing Economizers:

Non-condensing economizers are the most commonly used economizers. They are finned heat exchanger coils placed at the flue gas ducting located at the exit of the boiler. Non-condensing economizers are designed to maintain the flue gas temperature above its condensing temperature to avoid corrosion of the ducting of flue gas. Non-condensing economizer increases the overall efficiency of the boiler by 2% to 4%

Advantages of Economizers:

Economizer increases the efficiency and lifespan of the steam boiler and reduces the time and fuel required for the heating process, thereby reducing fuel consumption and cost. Some of the noteworthy benefits of economizers are:

The large quantity of water required to cool the flue gases before desulphurization is reduced with the help of economizers

• Increase in efficiency of the steam power plant
• Reduced steam consumption in the prime mover
• Reduced condensation loss in the pipes
• Reduction in turbine blade erosion to a great extent

Rakhoh Boilers, as one of the leading boiler manufacturers, supply boiler economizers for steam boilers. Rakhoh manufactures various types of economizer coils such as Plain Tubular Economizers, Finned Economizers, Iron Gilled Economizers, and many more. We also offer services like Cassette baffles for bends, Half Tubes Sleeves for upper tubes, SS full Sleeved tubes, etc. that extend the life of the economizer coils.