Plant profitability

One of the main objectives of a plant feasibility study is to assess the commercial viability of the proposed plant. The essential parameters of this calculation are the capital cost and cost of debt, the operating costs, the revenue on operation, and the plant life. It is also necessary to evaluate the risk that the values of these parameters may change. 

In the overview on project management, we referred to the concept of a plant lifecycle, of which the project is a part. In the following, we will discuss some of the lifecycle aspects which have to be considered when conducting a study and building a plant. 

Further operational performance enhancements are generally a matter of balancing the capital cost of the enhancement against future operational cost savings. Of course, these enhancements (or the plant features which secure them) may be specified by the client, in which case 

Or increased revenue arising from more, or improved, product. If revenue is regarded as a negative cost, the treatment is identical. 

For everyday decision-making, it is convenient to express the result in terms of a time pay-back period by which to ratio annual cost-savings to arrive at the discounted total of future savings. Having evaluated this figure once for the project, it becomes a criterion which can quickly be applied to each application. 

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The use of a Fischer-Tropsch (FT) process to produce long-chain hydrocarbons is well known in industry, and achieving the desired selectivity from the FT reaction is crucial for the process to make economic sense. It is, however, well known that a one-alpha model does not describe the product spectrum well. From either a chemicals or fuels perspective, hydrocarbon selectivity in the FT process needs to be thoroughly understood in order to manipulate process conditions and allow the optimization of the required product yield to maximize the plant profitability. There are many unanswered questions regarding the selectivity of the iron-based low-temperature Fischer-Tropsch (Fe-LTFT) synthesis. 

In a retrofit batch design, we optimize the batch plant profitability defined as the total production value minus the cost of any new equipment. The objective is to obtain a modified batch plant structure, an operating strategy, the equipment sizes, and the batch processing parameters. Discrete decisions correspond to the selection of new units to add to each stage of the plant and their type of operation. Continuous decisions are represented by the volume of each new unit and the batch processing variables which are allowed to vary within certain bounds. 

In industrial plants, large numbers of process variables must be maintained within specified limits in order for the plant to operate properly. Excursions of key variables beyond these limits can have significant consequences for plant safety, the environment, product quality and plant profitability. Statistical process control (SPC), also called statistical quality control (SQC), involves the application of statistical techniques to determine whether a process is operating normally or abnormally. Thus, SPC is a process monitoring technique that relies on quality control charts to monitor measured variables, especially product quality. 

Buy-back rate from the utility which is high enough to make the plant profitable... 

The total plant profitability model is configured in an ANN (artificial neural network) format, which is self-correcting and can be trained on the actual performance data of the plant based on past operation. 

The book is based on a series of workshops and specialist seminars given by the author dating Ifom 1996 in Singapore and Kuala Lumpur. The workshops focussed on production economics, improving plant profitability, feedstock supply and cost. The book is an updated and expanded version of the author s workshop notes. 

Consequently, investment decisions require capital budgeting. This plant profitability analysis is the evaluation and the selection of the best investments from a set of alternatives. Methods for evaluating investments include NPV and rate of return, among others, for private companies and benefit-cost ratio for public works projects. All these come under the purview of plant profitability analysis. 

The symbols are P for profit, / for equality constraints, g for inequality constraints, x for optimization variables, y for dependent variables, and / (constant) for updated parameters. The objective function is a scalar measure of plant profit it is usually the instantaneous profit ( /hr), because the optimization variables do not involve the time value of money. Typical equality constraints include material and energy balances, heat and mass transfer relationships, and thermodynamic and kinetic models, and typical inequality constraints include equipment limitations limit compressor horsepower, and distillation tray hydraulics. The optimization variables are flow rates, pressures, temperatures, and other variables that can be manipulated directly. The dependent variables involve intermediate values required for the detailed models for example, all distillation tray compositions, flow rates, and temperatures. Because of the fundamental models often used in RTO, the number of dependent variables can be quite large, on the order of hundreds of thousands. 

All garden enthusiasts know about the nice autumn crocus (Colchicum autumnale), which flowers in late autumn. It is not difficult to understand that this very conspicuous plant profits by containing a strong poison that protects it from pathogens and herbivores. It contains colchicine, which is very toxic and has a complicated structure. The substance is well known to plant breeders because it is used to double the number of chromosomes artificially in plants. A synthetic benzimidazole derivative, l-methyl-3-dode-cylbenzimidazolium chloride, was developed in 1960 as a curative fungicide against apple scab. Thiabendazole, another synthetic benzimidazole derivative, has been used as an anthelmintic since 1962. 

Either pure toluene or high content of Cg-" A (70 wt%) can be used as feedstocks for the process. In particular, aromatics (C gA) in the feedstock can be as much as 10 wt%. C A can also be converted into lower carbon aromatics, so that more benzene and mixed-xylenes can be produced and plant profitability is increased. 

In this section, two case studies are presented. The first is a relatively simple example involving one decision variable and one constraint, in which the venture profit for a process to manufacture ethyl chloride is maximized. In the second example, it is desired to optimize the operation of a multidraw distillation column, in which a mixture of normal paraffins is separated into four product streams, two of which are sidestreams. This involves four decision variables and a number of constraints. Although neither of the examples involves the optimization of accurate measures of plant profitability, detailed costing could be included. 

So as to optimise an economic or environmental performance. The former can be defined as a maximum plant profit or a minimum capital expenditure accounting for the environmental impacts involved and their imposed limits the latter can be the minimisation of the environmental impacts where all operational and structural network restrictions as well as cost limits are considered. 

Any of the mentioned hazards can potentially have a negative impact on plant profitability if it is not prevented in an efficient way. Random failures result in substantial costs of repair or replacement, and significant losses of power production, and... 

An example of an industrial concern being translated into an inspection program is the loss of plant profitability due to production losses associated with boiler tube failures. Underdeposit corrosion in steamgenerating systems is caused or enhanced by the breakdown of a protective magnetite film and/or the inability to form such a film. Production losses resulting from reduced steam capacity are far greater than the actual repair and maintenance costs incurred during shutdowns. The major contributors to the formation of deposits and scale are... 

Historically, the focus of optimization in chemical plants has been during the design phase, but since the 1990s this has changed because plant profitability can be enhanced by performing optimization of operating conditions on a repetitive basis. In a large plant, the... 

Georgiou, A., P. Taylor, R, Galloway, L, Casey, and A. Sapre. Plantwide Closed-Loop Real Time Optimization and Advanced Control of Ethylene Plant—(CLRTO) Improves Plant Profitability and Operability, Proc. NPRA Computer Conference, New Orleans, LA, November 1997. 

When the Board of Duectors authorizes a project, the decision to invest capital in the venture has been based on plant profitability. Real profitability depends on the return on the capital spent, when the return is made and how soon production of acceptable product is available at full flow sheet level. 

A key design consideration with exothermic reactions is the utilization of the heat of reaction. This energy optimization is often critical for plant profitability. The obvious heat integration technique is to use the hot reactor product to heat the cold reactor feed. The alternative would be to employ a hot utility to heat the reactor feed to near the reactor temperature and then a cold utility to cool the reactor product to the desired level. 

Each smelter, whatever its size, normally produces a range of lead products in addition to soft (refined) lead. These may include, standard lead alloys or speciality (often custom-made) products, all of which will incorporate a certain amount of value-added and consequently command a premium over the price of soft lead. Realised product prices will also depend on the degree of downstream integration by the smelter, specific local market conditions and particular contractual arrangements. The structure of prices is discussed, later, in Chapter 16. The production, marketing, and indeed, corporate strategies of companies will therefore have an important bearing on individual plant profitability and competitiveness. 

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