Steam optimal design

Table III. Energy and Exergy of Each Steam in the Optimal Design...

Obert and Gaggioli ( ) applied Second Law costing to the optimal design of steam piping and its insulation in a power plant. 

Several suppliers have stated that dual-purpose applications, such as in desalting plants are foreseen (Rolls Royce PWR 300, HRB 100-500 and Atomenergoexport VVER-440). It is not proposed to obtain an optimized design through a back pressure turbine but simply to bleed off high-pressure steam at the high pressure turbine. This is in itself a proven and simple method. 

Yu, W, Ohmori, T, Yamamoto, T, Endo, A, Nakaiwa, M, Itoh, N. Optimal design and operation of methane steam reforming in a porous ceramic membrane reactor for hydrogen production. Chem. Eng. J. 2007 62 5627-5631. 

After the optimal design variables for the extractive distillation column are determined, the total TAC can be calculated with the entrainer recovery column and the recycle stream included. Additional costs in the TAC include the annualized capital cost for the entrainer recovery column, the costs associated with the cooler from B2 on the entrainer feed, the operating costs of the steam and cooling water to operate the entrainer recovery column, and the entrainer makeup cost. As an example. Figure 10.13 shows the results of the optimization runs for Case 1 with N2 and Np2 as the design variables. The y axis is the TAC of the complete flowsheet. From the flgure, N2 should be 24 and Afe should be at Stage 9. 

Given a network structure, it is possible to identify loops and paths for it, as discussed in Chap. 7. Within the context of optimization, it is only necessary to consider those paths which connect two different utilities. This could be a path from steam to cooling water or a path from high-pressure steam used as a hot utility to low-pressure steam also used as a hot utility. These paths between two different utilities will be designated utility paths. Loops and utility paths both provide degrees of freedom in the optimization. ... 

While process design and equipment specification are usually performed prior to the implementation of the process, optimization of operating conditions is carried out monthly, weekly, daily, hourly, or even eveiy minute. Optimization of plant operations determines the set points for each unit at the temperatures, pressures, and flow rates that are the best in some sense. For example, the selection of the percentage of excess air in a process heater is quite critical and involves a balance on the fuel-air ratio to assure complete combustion and at the same time make the maximum use of the Heating potential of the fuel. Typical day-to-day optimization in a plant minimizes steam consumption or cooling water consumption, optimizes the reflux ratio in a distillation column, or allocates raw materials on an economic basis [Latour, Hydro Proc., 58(6), 73, 1979, and Hydro. Proc., 58(7), 219, 1979]. 

Since 1900, manufacturers have made many step changes in the basic design of steam turbines. New technology and materials have been developed to support the industry s elevation of steam conditions, optimization of thermal cycles and unit capacity. Steam turbines will continue to be the principal prime mover for electricity generation well into the twenty-first century. 

---