Boiler Efficiency vs. Steam Quality- The Challenge of Creating Quality Steam Using Existing Boiler Efficiencies

Abstract

A boiler works under pressure and it is not possible to see what is happening inside of it. The terms "wet steam" and "carry over" are every day idioms in the steam industry, yet very few people have ever seen these phenomena and the actual water movement inside a boiler has remained highly speculative. This paper and support test video of actual boiler operations will illustrate the effects steam quality vs. boiler efficiency during different boiler and steam system demands. There are four different operating situations that effect the steam quality. Each of the following situation will be described in detail using visual aids and supporting literature: Case I: On/Off Feedwater Control: Wide swings in the water level of the boiler can result in unnecessary low water alarms and shut downs. Case II: Reduced Operating Pressure: By running a boiler at a lower pressure, the boiling action within the boiler becomes much more violent causing water to be carried over in to the steam system. Case III: A Demand of 15% over Capacity: Over loading a boiler will cause excessive amounts of water to be carried along with the steam into the system. Case IV: TDS Control: Without proper control of IDS within the boiler carry-over of water into the steam system will occur causing damage to equipment and/or waterhammer.