Ambient temperature in ☌ and humidity of air in kg/kgĭiagram of a fire-tube boiler Fire-tube boiler Here, water partially fills a boiler barrel with a small volume left above to accommodate the steam ( steam space). Ultimate analysis of fuel (H 2, S 2, S, C, moisture constraint, ash constraint). To measure the boiler efficiency in indirect method, parameter like these are needed: Q, rate of steam flow in kg/h Hg, enthalpy of saturated steam in kcal/kg Hf, enthalpy of feed water in kcal/kg q, rate of fuel use in kg/h GCV, gross calorific value in kcal/kg (e.g., pet coke 8200 kcal/kg) Heat-loss method (or, indirect method) Input-output method (or, direct method) ĭirect method of boiler efficiency test is more usable or more common.īoiler efficiency = power out / power in = Q × (Hg − Hf) / (q × GCV) × 100% There are two methods to measure the boiler efficiency in the ASME performance test code (PTC) for boilers ASME PTC 4 and for HRSG ASME PTC 4.4 and EN 12952-15 for water tube boilers: Heat recovery steam generators (HRSGs) use the heat rejected from other processes such as gas turbine. Nuclear fission is also used as a heat source for generating steam, either directly (BWR) or, in most cases, in specialised heat exchangers called "steam generators" (PWR). Electric steam boilers use resistance- or immersion-type heating elements. The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or natural gas. The brittleness of cast iron makes it impractical for high-pressure steam boilers. Although such heaters are usually termed "boilers" in some countries, their purpose is usually to produce hot water, not steam, and so they run at low pressure and try to avoid boiling. Ĭast iron may be used for the heating vessel of domestic water heaters. That makes the longevity of older wrought-iron boilers far superior to that of welded steel boilers. Wrought iron boilers corrode far more slowly than their modern-day steel counterparts, and are less susceptible to localized pitting and stress-corrosion. In the 20th century, design practice moved towards the use of steel, with welded construction, which is stronger and cheaper, and can be fabricated more quickly and with less labour. This iron was often obtained from specialist ironworks, such as those in the Cleator Moor (UK) area, noted for the high quality of their rolled plate, which was especially suitable for use in critical applications such as high-pressure boilers. Historically, copper was often used for fireboxes (particularly for steam locomotives), because of its better formability and higher thermal conductivity however, in more recent times, the high price of copper often makes this an uneconomic choice and cheaper substitutes (such as steel) are used instead.įor much of the Victorian "age of steam", the only material used for boilermaking was the highest grade of wrought iron, with assembly by riveting. In live steam models, copper or brass is often used because it is more easily fabricated in smaller size boilers. 
However, ferritic stainless steel is often used in superheater sections that will not be exposed to boiling water, and electrically-heated stainless steel shell boilers are allowed under the European "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors. Stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. The pressure vessel of a boiler is usually made of steel (or alloy steel), or historically of wrought iron. In all cases the combustion product waste gases are separate from the working fluid of the steam cycle, making these systems examples of external combustion engines.
Where a large volume of hot gas is available from some process, a heat recovery steam generator or recovery boiler can use the heat to produce steam, with little or no extra fuel consumed such a configuration is common in a combined cycle power plant where a gas turbine and a steam boiler are used. In a nuclear power plant, boilers called steam generators are heated by the heat produced by nuclear fission. In some cases byproduct fuel such as the carbon monoxide rich offgasses of a coke battery can be burned to heat a boiler biofuels such as bagasse, where economically available, can also be used. In a fossil fuel power plant using a steam cycle for power generation, the primary heat source will be combustion of coal, oil, or natural gas. 4.2 Heat-loss method (or, indirect method).4.1 Input-output method (or, direct method).If this data is unavailable or inaccurate and you own or represent this business, click here for more information on how you may be able to correct it. VIEW ADDITIONAL DATA Select from over 115 networks below to view available data about this business.
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