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Displaying 301 - 320 of 522 stories.
September 1, 2009
More and more, the chemical process industries (CPI) are seeking out the benefits of flexible production and maximizing energy and material recovery. Process units are becoming tightly integrated, and the failure of one unit can seriously degrade overall productivity. Meanwhile, with the influx of larger and larger scale operations, even small changes in productivity can seriously affect profitability...
http://www.che.com/technical_and_practical/Multivariable-Predictive-ControlThe-Scope-is-Wider-Than-You-Think_5027.html
September 1, 2009
Plastics are most commonly produced and sold in pellet form due to the superior handling characteristics of pellets in downstream applications. From the moment the polymer is pelletized from its molten state, the pellets or granules undergo a series of handling steps as they move from the producer to the consumer. For instance, post-pelletization steps include: • Hydraulic conveying • Drying...
http://www.che.com/technical_and_practical/Measuring-Dust-and-Fines-In-Polymer-Pellets_5028.html
September 1, 2009
In more and more locations, the availability of fresh water resources is limited and water reuse is becoming increasingly important. For many industrial applications, the availability of water is essentially a “license to operate”. A large component of the water consumption in many chemical process industries (CPI) is high- and low-pressure boiler water. As such, reusing cooling water blowdown...
http://www.che.com/technical_and_practical/Strategies-for-Water-Reuse_5046.html
September 1, 2009
Multiple CSTRs (continuous stirred-tank reactors) are advantageous in situations where the reaction is slow; two immiscible liquids are present and require higher agitation rates; or viscous liquids are present that require high agitation rates. Unlike in plugflow reactors, agitation is easily available in CSTRs. In this article, batch and plugflow reactors are analyzed and compared to multiple CSTRs...
http://www.che.com/technical_and_practical/CSTR-Design-for-Reversible-Reactions_5052.html
August 1, 2009
Failure to register under REACH closes EU markets for thousands of chemical substances manufactured or marketed in the European Union, whether on their own, in preparations (formulations) or released from articles (finished products). A key policy objective of registration under REACH (EC Regulation 1907/2006 on Registration, Evaluation, Authorization and Restriction of Chemicals) — to shift the...
http://www.che.com/technical_and_practical/REACH-Looking-Beyond-Pre-registration_4976.html
August 1, 2009
Most engineers know what viscosity is, but may have trouble explaining it. To be brief, viscosity is resistance to flow. For handlers of all materials that flow, either while being processed or in an end-use, it is important to think about the materials’ flow characteristics. The bottom line is to come up with ways to measure viscosity so that you can quantify whether a material will flow the way it...
http://www.che.com/technical_and_practical/Viscosity-The-Basics_4977.html
August 1, 2009
Many branches of the chemical process industries (CPI) make use of impact comminution to process solid matter, such as minerals, foodstuffs, pharmaceutical products, and above all, products for the chemicals industry. Impact comminution is also used for coarse crushing, but the focus of this article is fine grinding with end-product particle sizes below 500 µm. The technology of impact comminution...
http://www.che.com/technical_and_practical/Fine-Grinding-With-Impact-Mills_4989.html
August 1, 2009
Cooling water systems that rely on cooling towers are a critical component at chemical process industries (CPI) facilities. However, during operation, these open recirculating systems concentrate the contaminants in the makeup...
http://www.che.com/technical_and_practical/Keeping-Cooling-Water-Clean_5005.html
July 1, 2009
The heat transfer sufaces of coal-fired process heaters and boilers often undergo severe fouling. If left intact, such deposits, consisting of slag from mineral matter contained in the coal, can reduce heat-transfer-surface availability, reduce thermal efficiency and cause corrosion. If the deposits are adherent and cannot be removed by conventional steam soot-blowers, shutdown and more rigorous cleaning...
http://www.che.com/technical_and_practical/The-Shotgun-Approach-Removal-of-Fouling-Deposits-on-Heat-Transfer-Surfaces-in-Coal-Fired-Process-Heaters-and-Boilers_4925.html
July 1, 2009
Despite the immense value and universal appeal of these additives for product designers, process engineers facing the day-to-day reality of full-scale production face a unique set of challenges. Dispersing these powdered additives into a liquid is one of the most formidable challenges in the chemical process industries (CPI). Although most can be dispersed fairly easily in a common laboratory mixer, when...
http://www.che.com/technical_and_practical/Disperse-Difficult-Solids_4926.html
July 1, 2009
Meanwhile, the revamp opportunities that a turnaround provides are, themselves, few and far between. Petrochemical refineries, for instance, typically try to get five years between major turnarounds to maximize on-stream time. Some equipment can be connected before an actual shutdown, but most of the so-called tie-ins must fall into place during the turnaround, which usually lasts only 20–50 days...
http://www.che.com/technical_and_practical/Revamps-Strategies-for-A-Smooth-Turnaround_4931.html
June 1, 2009
Figure 1.  Vibratory feeders are particularly well-suited for fragile or friable materials, and hard-to-convey powders Figure 2. Today’s advanced electromagnetic drives address many shortcomings of earlier designs The need to move, convey and feed materials exists in virtually all segments of the chemical process industries (CPI). Vibratory feeding and conveying equipment (Figure 1) has been...
http://www.che.com/technical_and_practical/Vibratory-Feeders-And-Conveyors-Useful-Selection-Tips_4815.html
June 1, 2009
A new correlation that matches most commercial trays The sieve tray has been in the distillation market place for many decades. It has been used extensively in distillation columns worldwide as a highly efficient vapor-liquid-contacting device. Many people have examined dry tray pressure-drop data for sieve tray decks and there have been several attempts to correlate these data. But the error of such...
http://www.che.com/technical_and_practical/Dry-Tray-Pressure-Drop-Of-Sieve-Trays_4816.html
June 1, 2009
Figure 1.  Many self-testing ground- ing clamps also monitor cable condition back to the designed ground point, and will alert the operator if the cable has worked tself loose or is broken We are all familiar with the effects of static electricity in everyday life — the sharp spark we experience as we approach a metal file cabinet or the crackle we feel as we remove a garment made of synthetic...
http://www.che.com/technical_and_practical/Avoiding-Static-Sparks-In-Hazardous-Atmospheres_4817.html
June 1, 2009
The whole-product-lifecycle approach presented here encompasses more than basic selection Typical discussions of flowmeter selection address specifications, technologies, accuracies and performance, but there are many other steps that are not normally considered. This article focuses on these often overlooked criteria, which inevitably have far-reaching and costly implications over the life of the...
http://www.che.com/technical_and_practical/Beyond-Flowmeter-Selection-Consider-Some-of-the-Most-Overlooked-Criteria_4818.html
May 1, 2009
Evaporation of moisture or volatile organic compounds (VOCs) from bulk solids usually takes place in two stages: one in which the drying rate is constant, and the second in which the rate decreases over time. Devolatilization during the first stage is rapid and can be readily accomplished in flash, spray, or fluidized bed dryers. In the second stage, however, the VOC or moisture removal rate is diffusion...
http://www.che.com/technical_and_practical/Designing-and-Operating-Gravity-Dryers_4768.html
May 1, 2009
By continuously monitoring for abnormal situations, such as a fire, and combustible or toxic gas releases, fire and gas (F&G) detection and mitigation systems are the linchpins to maintaining overall safety and operation of industrial facilities. The premise of these systems is to protect processes and the environment by providing early warning of incidents and enabling actions that prevent them from...
http://www.che.com/technical_and_practical/Fire-and-Gas-in-Safety-Systems_4769.html
May 1, 2009
Because temperature control is important in any process, a water-cooling system is a common component in chemical processing plants. For facilities located near coastal areas, the tendency is toward the use of seawater instead of river water for cooling purposes. Seawater has the advantage of having nearly a constant quality (chemical analysis), nearly a constant temperature and is available in large...
http://www.che.com/technical_and_practical/Engineering-Practice-Optimal-Cooling-Systems-For-Coastal-Plants_4770.html
May 1, 2009
In recent years, a growing number of projects throughout the chemical process industries (CPI) have been carried out using Engineer-Procure-Construct (EPC) contracts. Because such contracts typically involve the work of numerous subcontractor parties, they tend to be complex. As such, specialized tools are required to manage their information- and project-management needs. In general, operating companies...
http://www.che.com/technical_and_practical/EPC-Contractors-Selecting-an-ERP-Package_4771.html
April 3, 2009
I recently read Hydrogen-Pinch Analysis Made Easy Chem. Eng., June 2008, pp. 56–61. The paper presents an automated spreadsheet program to target the minimum fresh hydrogen resource for a hydrogen network. While the effort of the authors is appreciated, I do not agree with some claims in the paper, including the following: The authors do not acknowledge an earlier work by El-Halwagi (2003), which is...
http://www.che.com/technical_and_practical/Hydrogen-Pinch-Analysis-Made-Easy-Discussion-between-a-reader-and-the-authors_4682.html
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