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Archives :: Technical & Practical

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September 1, 2013
Solid and serrated fins (Figure 1) are widely used as heat transfer surfaces in boilers and heaters. The use of finned tubes makes heat exchanger equipment compact. The fluegas pressure drop is also decreased relative to a comparable plain-tube design, resulting in lower operating costs. Fin geometry, such as fin density (fins/in.), fin height and fin thickness, should be selected with care as it impacts...
http://www.che.com/technical_and_practical/Understanding-Finned-Heat-Exchangers_10954.html
August 1, 2013
Propylene has been established as an important part of the global olefins business, trailing only ethylene in terms of volume of product. Because inexpensive natural gas from shale in the U.S. is increasingly used as a feedstock for producing ethylene, lower quantities of three- and four-carbon olefins are available. For this reason, new chemical processes for on-purpose propylene using low-cost raw...
http://www.che.com/technical_and_practical/Methanol-to-Propylene-Technology_10789.html
August 1, 2013
The scaleup of liquid mixing systems does not have to be a mystery. The principles are quite well understood, although knowing which principles apply is not always obvious. Follow this guidance to improve operation. 1. Liquid mixing scaleup. Liquid mixing is the most common use of scaleup methods in chemical engineering. The concept of scaleup is to take small-scale results and predict results in...
http://www.che.com/technical_and_practical/Ten-Things-You-May-Not-Know-About-Liquid-Mixing-Scaleup_10818.html
August 1, 2013
Raw materials and energy represent two of the largest expenses in the chemical process industries (CPI). Energy reduction is necessary to sustain cost-effective production and manage capacity in the ever-changing CPI marketplace. Process simulation software can prove extremely valuable in evaluating energy reduction potential. This article discusses the successful application of process simulation software...
http://www.che.com/technical_and_practical/Absorber-Optimization-Employing-Process-Simulation-Software_10822.html
August 1, 2013
Manufacturers face seasonal supply-and-demand variations in their production cycle due to fluctuations in both market demand and supply of raw materials. Therefore, manufacturers need solutions that can help them to cope with this challenge in effective production planning. Pinch analysis, which has been used for resource conservation in the past few decades, has recently been extended to production...
http://www.che.com/technical_and_practical/Pinch-Analysis-for-Production-Planning-in-Manufacturing-Industries_10823.html
July 1, 2013
Polymer-based piping systems offer a number of advantages, along with some limitations, compared to metallic and other non-polymeric pipe materials. The use of thermoplastic piping in the chemical process industries (CPI) must be carefully considered on a case-by-case basis because of the constraints introduced by various CPI applications. Polymers remain only a small (~10%) part of the global CPI piping...
http://www.che.com/technical_and_practical/Polymer-based-Piping_10685.html
July 1, 2013
Polyethylene (PE) is the world’s largest-volume commodity polymer. Along with high-density (HDPE) and low-density (LDPE) polyethylene, linear low-density polyethylene (LLDPE) is one of the three main types of PE. The global market for LLDPE is over 20 million metric tons per year, corresponding to about 30% of the total PE produced. In LLDPE production, three major types of low-pressure technologies...
http://www.che.com/technical_and_practical/A-solution-based-route-to-LLDPE_10693.html
July 1, 2013
Security of SCADA (supervisory control and data acquisition) and other industrial control systems (ICSs) is a complex subject, and one that has received much attention in recent years. While modern industrial control systems use many of the same computers, operating systems and networking components as conventional business networks, the two kinds of networks are managed very differently. As a result, what...
http://www.che.com/technical_and_practical/Securing-Industrial-Control-Systems_10695.html
July 1, 2013
When considering project proposals for new processes in the chemical process industries (CPI), capital equipment costs often become the primary focus. The purpose of this article is to provide a detailed examination of the total cost of process equipment and the implications that the initial equipment cost has for longterm costs over the full life of the process. FIGURE 1. Initial capital costs alone are...
http://www.che.com/technical_and_practical/Lifecycle-Costs-for-Capital-Equipment-in-the-CPI_10697.html
July 1, 2013
Rotary valves are used almost universally in pneumatic conveying systems. They serve three main functions: 1) to provide a pressure-seal (airlock) between two adjacent processes, 2) to provide solids metering (feeding) and 3) to provide a combination of solids metering and a pressure-seal for feeding solids into a pneumatic conveying system. Rotary valves are common devices for feeding solids into a...
http://www.che.com/technical_and_practical/Rotary-Valves-in-Pneumatic-Conveying-Systems_10698.html
July 1, 2013
For most engineering-procurement-construction (EPC) projects in the chemical process industries (CPI), the data sheets developed at the beginning of the process provide the “shopping lists” that guide the procurement group on the purchase of equipment, system packages, instruments and more. Data sheets should function as the central document, into which all final result of design or...
http://www.che.com/technical_and_practical/Getting-the-Most-Out-of-Data-Sheets_10699.html
June 1, 2013
Calculating the volume of a liquid in a vessel of a complex shape is a common task for chemical engineers. However, there are several difficulties associated with accurately carrying out this calculation. In my own experience as a chemical engineer, I have become familiar with the complexities of calculations related to determining the volume of a liquid contained in a vessel with an irregular shape...
http://www.che.com/technical_and_practical/Solving-Vessel-Equations-A-Better-Way_10573.html
June 1, 2013
Ethylene is arguably the most important building block of the petrochemical industry, frequently produced via steam cracking of a range of petroleum-based feedstocks. Rising oil prices and concerns about global warming have motivated research into ethylene manufacture from renewable sources. The “green” ethylene made from ethanol (for example, from corn, sugarcane or lignocellulosic biomass)...
http://www.che.com/technical_and_practical/Ethylene-Production-via-Ethanol-Dehydration_10581.html
June 1, 2013
Ongoing advances in the design and use of dry gas seals (DGSs; [ 1]) — as an alternative to traditional oil-lubricated wet seals [ 2] — have helped to improve the reliability and efficiency of compressors throughout the chemical process industries (CPI). One of the major design considerations in mechanical seals is how to protect seal faces from wear, as one face rotates close to a static face...
http://www.che.com/technical_and_practical/Compressors-N2-Expands-the-Applicability-of-Dry-Gas-Seals_10582.html
June 1, 2013
Chemical technology is in a state of constant innovation and evolution that is being spearheaded by laboratory researchers across the world. Within the past decade, research specific to “green” or bio-based chemicals has gathered funding and momentum as broad-based opinion has shifted toward themes such as sustainability, renewables and conservation. This momentum has impelled advances in green...
http://www.che.com/technical_and_practical/From-Concept-to-Commercial-Production_10584.html
June 1, 2013
Process sensors and actuators provide a wealth of information about their status. The Namur recommendation NE 107 that proposes standardized, easily understandable status indicators was issued by the International User Association for Automation in Process Industries (Namur; Leverkusen, Germany; www.namur.de), in an effort to enable plant operators to check the current condition of their field devices...
http://www.che.com/technical_and_practical/Compliant-Remote-IOs_10587.html
June 1, 2013
With the advent of smart or intelligent field devices, a wealth of digital information has become available. However, what does the host system do with these data? The field device transmits a bucket of bits to the host system. How are these data converted into information that a human can interpret? Where is the information displayed? Should the information be stored as persistent data? These questions...
http://www.che.com/technical_and_practical/Understanding-FDI_10588.html
June 1, 2013
During process operations, elevated pressure inside of isolated zones within a process or system can be rapidly reduced by the release of gas and vapor to a dedicated blowdown network. Analysis can be carried out to determine whether a given pressure-relief device will provide sufficient protection from potential vessel rupture for an unwetted-wall vessel or a vessel containing a high-boiling-point liquid...
http://www.che.com/technical_and_practical/Vapor-Depressurization-Concept-and-Implementation_10589.html
May 1, 2013
Inline viscosity measurements can give continuous, realtime readings of a fluid’s viscosity during processing and consequently, can provide a means to automate the viscosity control of process fluids. While it is difficult to control all factors in the process that can affect a fluid’s viscosity (such as temperature, air bubbles, shear history, turbulence and so on), if these factors are kept...
http://www.che.com/technical_and_practical/Inline-Viscosity-Measurements_10470.html
May 1, 2013
Occasionally, direct fired heaters that have operated satisfactorily for long periods of time subsequent to startup develop operating problems that do not allow for operation at design conditions, as specified in the manufacturers API data sheets for the heater. Performance that may be guaranteed, or otherwise specified by the supplier would include the type and characteristics of the feedstock processed...
http://www.che.com/technical_and_practical/Correcting-Improper-Performance-of-Direct-Fired-Heaters_10471.html
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