Archives :: Technical & Practical

Displaying 501 - 520 of 538 stories.
July 1, 2006
    Trends in the worldwide chemical process industries, especially a steep rise in the compression and liquefaction of gases to lower the costs of their storage and transportation, have heightened the engineer's need to have a working familiarity with chemical-process operation at low (nominally, below 0°C) and cryogenic (below –100°C) temperatures. In addition to natural gas...
July 1, 2006
    The usage of Coriolis flowmeters for measuring mass flowrates has become widespread in the chemical process industries, and the range of fluids with which these meters can be employed is likewise diverse. Among those applications, Coriolis flowmeters can readily be applied to cryogenic fluids (contrary to conventional flow-measurement practice with these fluids), provided that the measurement...
July 1, 2006
    The beauty of fiber-optical spectroscopy is that small, inexpensive devices with no moving parts bring their capacity to where the samples are, rather than the other way round. As a result, spectra can be recorded in almost real time, which means that information about composition, concentration and other chemical parameters can be gathered alongside of temperature, pressure and flowrate. The...
July 1, 2006
    Air pollution is monitored by many different regulatory programs, some of which require that emissions be measured continuously. This task is often accomplished by directly measuring air pollutants with continuous emissions monitoring systems (CEMS). In recent years, innovative technology has enabled a new approach that predicts emissions from process variables. Industry welcomes predictive...
July 1, 2006
    Processes incorporating bulk solids handling are ubiquitous in the chemical process industries (CPI), including the chemical, petrochemical, polymer, biochemical, agricultural chemicals, paints/pigments, energy and power, pulp and paper, and pharmaceutical industries, to name a few. Studies conducted during the past two decades have shown that:     More than 50% of products are...
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...
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