Chemical plant design engineering materials

In general, the following items are considered vital in plant location proximity to market, raw materials, transportation, labor supply, water supply, power supply, economic interrelation with other industries, and specific plant requirements. There are other plant and process location matters that are of real importance to, and exist as real responsibilities of, the chemical plant design engineer of commercial plants for the manufacture of chemicals and chemical formulations, such as land, local ordinances, public improvements, utilities, waste disposal, and climatic conditions. All the factors that enter into the problem of plant or industry location also affect the choice of local sites and must be considered by the design engineer (see Chap. 7). 

Fire and Explosion Prevention. Prevention of fire and explosion takes place in the design of chemical plants. Such prevention involves the study of material characteristics, such as those in Table 1, and processing conditions to determine appropriate ha2ard avoidance methods. Engineering techniques are available for preventing fires and explosions. Containment of flammable and combustible materials and control of processes which could develop high pressures are also important aspects of fire and explosion prevention. 

The design practices compiled in this volume were derived firom the literature of the American Society of Testing Materials (ASTM), the American Petroleum Institute (API), the ANSI Codes, a review of company specific literature including company design practices and general publications, and the author s personal notes compiled over the years as a consultant and practicing engineer, as well as an instructor to Venezuelan refinery and chemical plant operations. 

Figure 1-36. Process engineering costs (1975), based on process engineering charged at 14 per manhour. Chemical plant engineering operations, includes flowsheet development and drafting, material and heat balances, equipment designs, ratings, checking, and bid reviews and selection of equipment. By permission, E. E. Ludwig [7].

The chemical and petrochemical industries are highly capital intensive and this has two important implications for the plant designer. Before the expenditure for any plant is approved, a discounted cash flow (DCF) return on capital invested is projected (Section 9.1). The capital cost of the plant is a key factor in deciding whether the DCF return is above or below the cut-off value used by a company to judge the viability of projects. Thus, there is always strong pressure on the materials engineer not to overspecify the materials of construction. 

The density of a material is a function of temperature and pressure but its value at some standard condition (for example, 293.15 K or 298.15 K at either atmospheric pressure or at the vapor pressure of the compound) often is used to characterize a compound and to ascertain its purity. Accurate density measurements as a function of temperature are important for custody transfer of materials when the volume of the material transferred at a specific temperature is known but contracts specify the mass of material transferred. Engineering applications utilize the density of a substance widely, frequently for the efficient design and safe operation of chemical plants and equipment. The density and the vapor pressure are the most often-quoted properties of a substance, and the properties most often required for prediction of other properties of the substance. In this volume, we do not report the density of gases, but rather the densities of solids as a function of temperature at atmospheric pressure and the densities of liquids either at atmospheric pressure or along the saturation line up to the critical temperature. 

Chemical engineering has traditionally focused on commodity chemicals in its research and education. Most of its teaching materials are related to the design of chemical plants and petroleum refineries. Although much has been achieved by Cussler and Moggridge, and Seider, Seader and Lewin in their books to fill this void, more needs to be done to cover the numerous product areas. Most importantly, we have to clearly identify, and to develop if necessary, all the principles, skills and tools that the chemical engineers should know in order to perform on their job in various product sectors. 

In this volume, there is an account of the basic theory underlying the various Unit Operations, and typical items of equipment are described. The equipment items are the essential components of a complete chemical plant, and the way in which such a plant is designed is the subject of Volume 6 of the series which has just appeared. The new volume includes material on flowsheeting, heat and material balances, piping, mechanical construction and costing. It completes the Series and forms an introduction to the very broad subject of Chemical Engineering Design. 

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