Boiler Heat Balance

Boiler performance parameters such as efficiency and evaporation ratio, decreases with time due to poor combustion, surface fouling of heat transfer, poor operation and bad maintenance. Even for a new boiler, for reasons such as poor fuel quality and water quality can lead to poor performance of the boiler. Boiler heat balance can help in identifying heat loss that can or cannot be avoided. Boiler efficiency tests can help in finding the deviation efficiency of the best boiler efficiency and target the problem areas for corrective action.

The process of combustion in the boiler can be described in terms of flow energy diagram. This diagram illustrates graphically how the incoming energy from the fuel is converted into useful flow energy and the flow of heat and energy loss. Thick arrow indicates the amount of energy contained in each stream.

Figure 1: Diagram of Boiler Energy Balance

Boiler heat balance is balance of the total incoming energy to the boiler and that leaves the boiler in different form. The following figure provides a range of loss that occurred for steam generation.

Figure 2: Heat Loss in Coal-Fired Boiler