Archives :: Technical & Practical

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June 1, 2006
    Volatile organic compounds (VOCs), together with particulate matter, sulfur oxides and nitrogen oxides, are major components of air pollution that can lead to serious environmental and health hazards. Physical, chemical and biological treatment methods are available to remove VOCs from the air by either recovery or destruction [1-3]. Biological treatment methods, while less well-established...
June 1, 2006
    Intelligent — and thorough — preparation of a process-design-basis document can make the difference between a high-quality design for a chemical-process project and a poor one. The process-design-basis document represents the owner’s instructions to the design engineering organization about what the owner wants designed, and how the owner wants the process design to be done...
June 1, 2006
    Early predictions suggested that solvents would eventually be eliminated from industrial applications because of health and environmental concerns. After a short period of a small decline in solvent use in 1990s, the solvent demand is now growing steadily by 2.3% per year. At the same time, there have been changes in the types of solvents that are being used today. The general trend is...
June 1, 2006
    Accurate temperature measurement can often be quite challenging, especially in situations where process temperatures are extremely high (above 800°F), the target is in motion, or the need to avoid contaminants is significant. Infrared (IR) temperature-sensing offers an attractive solution. IR devices function basically by measuring infrared energy at a distance. Infrared energy is emitted...
May 1, 2006
    Accurate prediction of particulate-solids flow behavior during storage and feeding has eluded all but the most experienced solids handling experts. Often the process engineer is faced with the awkward task of making sense of bulk behavior. A powder sample held in a jar may appear to be free flowing, but hammer rash — jargon for the practice of hitting hoppers with pipes to dislodge...
May 1, 2006
    There are several reasons why composite fiberglass-reinforced-plastic (FRP) pipe has been replacing conventional pipe, and why this still relatively new material (see box, p. 46) should be kept in mind whenever piping is being specified for a new or a revamp project. Engineers involved with specifying or using FRP pipe should have a clear understanding of its nature and properties. A good...
May 1, 2006
    Among pilot plants, those in petrochemical or petroleum-refining service pose special risks of fire and/or explosion. The key strategies to minimize those risks are these: properly conducted preconstruction safety reviews; leaktight design and construction; close attention to area electrical classification; well-designed ventilation; well-planned storage; properly conducted maintenance; and...
May 1, 2006
    It’s an old saw, but I’ve long held that process development is very much a team effort. Developing safe, robust and scaleable chemical processes calls for close collaboration between synthesis chemists, process development engineers and pilot plant personnel. But experience shows that, particularly in many fine chemical and pharmaceutical organizations, researchers fail to put...
April 1, 2006
    Fundamental to the chemical process industries (CPI) — whether specialty or bulk chemicals, pharmaceuticals, food products, minerals processing, environmental protection or other products or activities — is the need for mixing. The wide variety and complexity of mixing tasks encountered in industrial applications require careful design and scale up to ensure that effective mixing...
April 1, 2006
    Liquids are accumulated and stored in tanks of various shapes and sizes throughout the chemical process industries (CPI). A small number of companies have made the design, fabrication and erection of these vessels their specialty. Initially, however, it is the process engineer who sizes and specifies tanks according to a specific application’s needs. In order to develop a data sheet for...
April 1, 2006
    Typical process utilities include electricity, process steam, refrigerants, compressed air, cooling water, heated water, hot oil, process water, demineralized water, municipal water, and river, lake, or ocean water. For preliminary cost estimates, waste disposal cost can also be treated like a utility expense. Unlike capital, labor, and other expenses, utility prices do not correlate simply...
April 1, 2006
    At present, around 540 billion Nm3 of hydrogen is produced worldwide, and the trend is upward (Hydrogen: The Real Action Is Today, CE, February, pp. 28ff). The numerous chemical-process and other industrial applications of this colorless, odorless gas vary widely as regards the quantities and purities required. Thus, it is useful for the engineer to have a working knowledge of the several...
April 1, 2006
    Cartridge trays, defined below, can be the perfect hardware solution for distillation columns that are less than 3 feet (0.9m) in diameter and have a unique need for trays. Packing is usually the preferred choice for small-diameter columns, but there are several circumstances in which trays are advantageous. Examples include fouling systems, certain foaming systems, high-pressure applications...
April 1, 2006
Most chemical processes must produce products that are uniformly mixed. There have been many articles written about preventing particle segregation during bulk solids flow; and ensuring a mass flow pattern is a common suggestion. But mass flow alone is not necessarily the answer to all segregation problems that can occur in silos and tanks. We will focus on the two major mechanisms of segregation; namely...
March 1, 2006
    Solvents have been used for centuries and in all type of industries for the processing, manufacturing and formulation of goods. In the chemical process industries (CPI), solvents are used in various process-operation steps such as separation (of gas, liquid and/or solid), reaction (as reaction medium, reactant, and carrier), degreasing, washing and many more. As part of product formulations...
March 1, 2006
    Depending on their location and on other factors, chemical-process-industries (CPI) plants obtain their process water from a diverse range of sources (see Process Water Supply — the Big Picture, Chem. Eng., May 2005, pp. 32–34.). The water from most, if not all, of these sources requires some, if not a great deal of, contaminant removal onsite in order to make the water suitable...
March 1, 2006
    Fuel costs rose sharply in 2005 because of hurricane damage to U.S. interests in the Gulf of Mexico, and international developments in the oil supply market. Competing fuels — coal and natural gas — rose in price in lockstep. Natural gas has risen in cost, and has been reported to be as much as $17/MM Btu in December 2005 for industrial use in the northeastern U.S. As operating...
March 1, 2006
    Engineers often need to predict the cost of piping and pipefitting associated with a process unit. Even though detailed prices are available, finding and organizing them takes time and costs money. For those needing a quick method of approximation (such as for a pre-design estimate), a short-cut piping cost method is presented in this article. For convenience and compactness, the relevant...
March 1, 2006
    Minor components trapped in distillation columns can react to form solids that cause major problems. The conventional responses to this situation focus upon dealing with the solids after they have become formed. A better strategy consists of preventing or minimizing the solids formation in the first place, by changing the column operating conditions.   Understanding the situation The...
February 1, 2006
    A clear definition of what a project will include can go a long way in helping to reach the desired objective. Spending the time upfront to seek input from pertinent parties and to scope out the details can prevent frustration, unexpected costs and sometimes insurmountable obstacles later on. A project scope defines what a project encompasses. It outlines the complete story by describing what...
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