Optimizing steam system configuration

In a process plant, the steam system is operated with a large amount of steam letdowns from 610 to ISOpsig and from 150 to 60psig in summer and winter operation, respectively, as well as 60psig venting in summer. 

In another process plant, the steam system operates with a large amount of LP vent. To prevent loss of valuable condensate due to LP vent, a condenser was installed to cool down the LP steam and return LP condensate back to the deaerator. Although this solution saves condensate, it did not resolve the LP long issue. It was later identified that a driver switch could help to reduce the LP vent In the boiler house, there are three forced draft (FD) fans currently run by MP-LP extraction turbines but fans have spare motor drivers. The operation policy acceptable to the plant was to use steam turbines for reliability reasons. The engineer wanted to establish the value of the driver switch to minimize the LP dump. 

After discussions with deliberation, the operating policy was revised so that one FD fan can be electrically driven when three boilers are online. The reason for this practice is that, in the event of a loss in eleetrieity supply, the steam load can be handled by the two remaining boilers. This ehange was evaluated after a few months later. Since the motor worked fine, it was deeided by the utility supervisor that two FD fans were run by motor while one fan run by turbine. As a result of change in the operating policy, the majority of the above benefit was captured. 

The primary purpose of the steam system is to produee steam to satisfy the process steam demand at different pressure levels. If the steam system has no cogeneration. 

The parameter influencing cogeneration is the ratio of power to process heat that can be supplied by a steam system (Kenney, 1984). This ratio is named as R ratio, which is expressed as 

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Although the details of establishing steam balances are discussed in Chapter 16 while steam equipment modeling equations are given in Chapter 15, the intention here is to combine all the related equations to develop a complete simulation and optimization model for the steam system. For specific applications, users can revise the model by providing specific configuration and conditions for the steam system. 

In the process industries, the Simplex algorithm has been applied to a wide range of problems, such as the optimization of a total plant utility system. A general steam utility configuration, typically involving as... 

The thermal integration of the system has a significant impact on the fuel conversion efficiency of the hydrogen production system. An optimal process configuration that generates the process steam with minimum parasitic losses was selected, and the fuel conversion efficiency on an LHV basis was estimated to be 75.2%. Compressor calculations showed that electricity required was around 1% of the LHV of the fuel. 

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