Potential of Waste Heat recovery from a Boiler Stack Economizer

Abstract

Sharply increasing cost of oil across the globe has resulted in initiation of energy efficiency strategies in manufacturing and commercial industry so as to reduce the cost of producing goods and services and in Kenya trends indicate that energy cost accounts for up to 50% of production costs which leads to diminished prize competitiveness of locally produced goods and services and reduced profits for investors. Waste heat recovery has emerged as an area of increasing importance in energy management as a means of reducing energy cost.

One of the preferred options for cutting the fuel oil cost in steam generation systems is a flue gas stack economizer. The purpose of this study was to evaluate the effectiveness of preheating boiler feed water using heat discharged in flue gases. This was carried out on a steam generation system with an economizer. It was found out that the economizer improved boiler efficiency from 74 % to 79% which contributed to a net savings in fuel oil consumption equivalent to 453.6 tonnes per annum. This result confirmed that the potential of waste heat recovery in boiler stack economizer is huge and the saving in energy is significant, which justifies its use for waste heat recovery.