The energy absorbed by steam is distributed among feedwater heating (sensible heat), boiling (latent heat), superheating, and reheating functions. The distribution ratios are a function of steam pressure, as can be seen from steam tables or from Fig. 3.6. If the latent heat is large as in low pressure steam, a large furnace is required […]

The terms boiler and steam generator are often used in the same context. Boilers may be classified into several categories as follows: By Application: Utility, marine, or industrial boiler. Utility boilers are the large steam generators used in power plants generating 500-1000 MW of FIgure 3.3a Fire tube boiler—wetback design. Electricity. They are generally fired […]

Steam generators, or boilers as they are often called, form an essential part of any power plant or cogeneration system. The steam-based Rankine cycle has been synonymous with power generation for centuries. Though steam parameters such as pressure and temperature have been steadily increasing during the last several decades, the function of the boiler remains […]

The following points may be considered while developing specifications for heat recovery applications. 1. Because there are numerous applications of heat recovery, it is always good practice to start off the specifications by describing the process that generates the flue gases, because that gives an idea of the nature of the gas stream. With a […]

I have developed a simulation program called HRSGS to perform these complex design and off-design performance calculations. Basically the desired HRSG configuration is built up by using the six basic modules shown in Fig. 2.19. By using the common economizer or common superheater concept, one can config­ure complex multiple-pressure HRSGs, as shown in the examples […]

It is possible to predict the performance of water tube HRSGs in clean gas applications by using a simulation process instead of physically designing the unit. Thus anyone familiar with heat balances such as consultants and those planning cogeneration or combined cycle plants can obtain a good idea of the performance of the HRSG under […]

The design procedure for waste heat boilers is quite involved. With a given set of inlet gas conditions such as flow and temperature, we have to see how the various heating surfaces respond. The surfaces could consist of bare or finned tubes. The superheater could have one or more stages; a screen section may or […]

The sizing procedures for fire tube boilers are discussed in Q8.10. It may be noted that the tube size plays a significant role in minimizing the length of the boiler. With small gas flows, one may consider multi-gas-pass design, which can reduce the overall length. Tube sizes vary from 1.5 to 2.5 in. OD; smaller […]

Fouling is a serious concern in both fire tube and water tube boilers, particularly with dirty gas streams. It affects not only the waste heat boiler performance but FIgure 2.14 D-type waste heat boiler for operation with burner and waste heat. (Courtesy of ABCO Industries, Abilene, TX.) FIgure 2.15 Waste heat boiler in carbon black […]

In chemical and industrial plants, several by-products are generated in solid, liquid, and gaseous forms that have to be safely destroyed to prevent potential environmental damage. These by-products come from petroleum refining and petrochemical, pharmaceutical, paper and pulp, and plastics production. Small quantities of by-products are stored in drums and placed in landfills, but the […]