Energy-Efficient Steam Boiler Systems in the World Air, water and steam are three media commonly used to distribute heat to process loads. However, steam has several advantages compared to hot air and hot water. These advantages include. • the heat carrying capacity of steam is much greater than air or water • steam provides its own locomotive force. • steam provides heat at a constant temperature Principles of Energy-Efficient Steam Systems Energy Balance Approach The figure below shows the primary energy flows into and out of a steam system.
Basic steam system
Steam System Components Boilers and Steam Generators Steam boilers are broadly classified as ‘fire-tube’ or ‘water-tube’ boilers. In fire tube boilers, the boiler shell contains the water/steam and hot combustion gasses pass through the tubes to heat the water/steam. In water-tube boilers, the water/steam passes through tubes and the hot combustion gasses pass through shell of the boiler. The two types of boiler can be used in different situations to meet the industry needs for a higher efficiency. Fire-tube boilers are popular for smaller applications requiring saturated steam at less than 150 psig because of their low first cost and durability. The large volume of water/steam serves as thermal mass which enhances steady operation. However, because the steam is generated on the shell side, the shell itself is a pressure vessel, making it difficult to generate steam at high pressures. In addition, the large surface area causes relatively large heat loss, which varies from about 0.5% of input energy at full-fire to a much higher fraction at low loads.
Difference between fire tube and water tube boiler
Steam generators are like water-tube boilers, except that they are made from light- weight materials. In many jurisdictions, the lack of a dedicated pressure vessel enables steam generators to be used without a boiler operator. The light weight materials and absence of a large holding tank allow steam generators to come up to pressure quickly in a manner of minutes. This enables steam-generators to be turned on and off as needed, reducing standby losses. Installing the water-tubes in a counter-flow configuration to the path of the combustion gasses increases thermal efficiency. Steam boiler can be used for power generation, textile industry, food processing, sterilization and so on. ZG boiler has developed horizontal steam boiler use oil, gas, coal, biomass and waster heat as energy to provide various steam for the world industry.