Archives :: Technical & Practical

Displaying 481 - 500 of 533 stories.
November 1, 2006
    The need to transfer bulk-solids materials from the outlet of a bin or from a conveyor, to a process, truck, or another bin is ubiquitous throughout the chemical process industries (CPI). Transferring material using equipment designed to mechanically convey chemicals works quite well, especially for long distances; however, for short distances, it can be prohibitively expensive and...
October 1, 2006
    Water is an essential resource for the chemical process industries (CPI), with steam, cooling water and process water as just a few examples of its many applications. When readily available, this essential commodity is often taken for granted. There is, however, a risk of losing the availability of classic water resources such as groundwater, river water or potable water for an industrial...
October 1, 2006
    The process industries are extensive users of energy. But it is now clearly established that a large amount of this energy is wasted, essentially in the form of heat rejected to the environment through gaseous or liquid effluents. The temperature level of this heat makes it of no use by the process; and at the same time, in many cases, it cannot be economically upgraded. Examples of...
October 1, 2006
    Provided that they are updated when appropriate to keep them relevant, time-tested heuristics rules based upon experience, also referred to as rules of thumb, can be useful for the design, specifying and operation of several kinds of equipment used in process plants. The first and foremost heuristic rule is that the engineer should not shy away from using heuristics - and the second rule is...
October 1, 2006
    Since its introduction to the market in 1959, chlorinated polyvinyl chloride (better known as CPVC) has proven suitable for use in a wide variety of chemical process environments. Because it is inert to most mineral acids, bases, salts and aliphatic hydrocarbons, it offers a more reliable, long-term performance than many other materials, including metals and most non-metallic alternatives. In...
September 1, 2006
    Since their inception, data buses have been highly acclaimed in the chemical process industries (CPI) for their potential to achieve interoperability and substantial wire-savings - advantages that are particularly easy to envision for a theoretical case in which a plant is constructed from the ground up and communicates by a single data bus. In the real world, however, the majority of...
September 1, 2006
    The reason for installing a bus is generally four-fold: to reduce costs; to speed and simplify control system design, installation, and startup; to provide alarming and troubleshooting diagnostics; and to gather valuable information about the process itself.   Today, we specify bus-connected automation almost exclusively for both new automation systems and retrofits in applications...
September 1, 2006
    The ANSI/ISA-S84.01-1996 standard, which has guided North American users for the past decade in designing safety instrumented systems (SIS) has migrated to a new international standard based on the IEC 61511 and is now known as ANSI/ISA-84.00.01-2004 (IEC 61511 Mod). Over the past few years, global chemical-process-industries (CPI) users have started to adopt this new standard, particularly...
September 1, 2006
    Distillation, based on differences in the volatility of components, is the most common unit operation for separating homogeneous mixtures. In simple distillation columns, a single feed stream is separated into two product streams. Complex columns are those that involve either two feed streams or three product streams - a side-stream in addition to the top and bottom products. These complex...
August 1, 2006
    For many years, the job of a control room operator at a petroleum refinery or chemical plant was seen as relatively simple: Keep the process running and fix it when it breaks. That perception is changing as more operators take on additional responsibilities for improving energy usage and process efficiency while maximizing production. Meanwhile, many companies have reduced the number of...
August 1, 2006
    Process engineers rely heavily on analytical instrumentation to ensure product quality. Properly designed systems help prevent contaminated fluids and gases from being delivered to consumers, or from reaching the next stage of production. Catching any problems as early as possible can yield significant savings in reduced product loss and system maintenance. Catching them efficiently lies...
August 1, 2006
    If your estimate for a project's capital cost is too high or too low, incomplete or wrong, a poorly developed scope is the mostly likely cause. In almost all cases, project cost estimating is more accurate than the scope used to develop the estimate. (To develop a good project scope, please refer to "Get Your Scope Straight for Project Success," CE, February, pp. 36-38). Yet good...
August 1, 2006
    In widespread use throughout chemical process plants, centrifugal pumps are often employed (and taken for granted) in severe service conditions. Consequently, it is hardly surprising that problems can arise during their operation. A major difficulty facing the chemical process industries today lies in the limited number of people who have enough skill and experience to diagnose and rectify...
August 1, 2006
    In the pharmaceutical, biotech and food processing industries, ingredients are transported, mixed, heated and cooled assuming the assurance of product purity required by lawmakers and taken for granted by consumers. Integral to the design of fluid-handling systems that must meet some of the most stringent standards of cleanliness in the world are equipment specifications that minimize the...
August 1, 2006
    Myths and misconceptions become part of accepted practice if repeated often enough. They are propagated by lack of fundamental particle-technology knowledge and by certain commercial interests. The list of presented here is by no means exhaustive. We have, however, made an attempt to cover a broad range of topics to highlight the widespread nature of these misconceptions. They are broken down...
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...
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