TABLE OF CONTENTS Steam boilers are required for the generation of high pressure steam to drive turbogenerators in central power stations or they may be used to supply steam for process requirements, for example in steam-methane reforming. In some cases, as at the Sasol plant in South Africa, the boilers supply steam for both process requirements (primarily coal gasification) and for power generation. The general design and layout of boilers for process steam and power generation is similar but may differ in detail; for example, in ammonia plant steam is generated also in other pieces of equipment and fed to the steam drum; consequently the number of connections to the drum is greater and this may increase the build-up of stress during fabrication.
A steam power station contains many thousands of welds and the failure of just one can result in a shutdown of 2 3 days, so that good weld quality is of great importance.
The maximum attainable efficiency ? of a steam engine is:
where T i is the steam inlet temperature and T o the exhaust temperature, all in K. Therefore, since T o is necessarily close to atmospheric temperature, high efficiency is obtained by increasing the steam inlet temperature to the turbines. The degree to which such an increase is economic depends upon the price and availability of fuel. High temperatures and pressures make heavy demands on materials of construction and increase operating risks. Thus, in the 1960s, when oil...
