Archives :: Technical & Practical

Displaying 161 - 180 of 527 stories.
February 1, 2012
Various misconceptions arise when it comes to the thermal design of cooling towers. Sometimes related parameters, such as range, approach, effectiveness, liquid-to-gas ratio ( L/G), wet-bulb temperature, cooling water temperature, relative humidity, number of transfer units (NTU) and other terms create a confusion for the designer in effectively sizing, selecting and evaluating a particular cooling tower...
http://www.chemengonline.com/technical_and_practical/Effective-Thermal-Design-Of-Cooling-Towers_8949.html
February 1, 2012
  Screw compressors are widely used throughout the chemical process industries (CPI) and represent a substantial percentage of all positive-displacement compressors that are now sold and in operation in CPI facilities. In general, screw compressors are efficient, reliable, simple and compact compressors that are competitive from both an initial cost and an operating cost standpoint compared to other...
http://www.chemengonline.com/technical_and_practical/Choosing-Oil-injected-Screw-Compressors_8954.html
February 1, 2012
The pursuit of manufacturing excellence is a strong theme across all of the chemical process industries (CPI). Improving operations by eliminating variability and waste, a cornerstone of the six sigma approach, is essential for competitive performance in the global marketplace. In addition, of course, health, safety and the environment (HSE) remains the subject of intense scrutiny and concern. Within this...
http://www.chemengonline.com/technical_and_practical/Control-Strategies-Based-On-Realtime-Particle-Size-Analysis_8955.html
January 1, 2012
Mechanical integrity is an essential consideration in heat exchanger design. The most common threat to this integrity is tube bundle vibration. So, the computer programs used for heat exchanger design incorporate procedures that assess this threat. However, such analysis is generally undertaken after exchanger geometry has been identified. The result can be that geometry that is optimal in terms of thermal...
http://www.chemengonline.com/technical_and_practical/Designing-Shell-and-Tube-Heat-Exchangers-Avoid-Vibration-From-The-Start_8834.html
January 1, 2012
Projects have been undertaken by nations, private enterprises and individuals for more years than recorded history. Over the last three decades, project execution in the chemical process industries (CPI) has become almost standardized, with the general adoption of certain well-known project management procedures including the Front-end Loading (FEL) process and the “Body of Knowledge.” Those...
http://www.chemengonline.com/technical_and_practical/Ten-Tips-For-Smart-Project-Managers_8835.html
January 1, 2012
In the chemical process industries (CPI) it is relatively common to use a homogeneous two-phase flow model to predict the pressure drop through the shell-side of horizontal heat exchangers that handle two-phase mixtures. Recent experimental studies reported by HTFS [1, 2], however, have shown that this approach leads to overprediction of pressure drop and to overprediction of thermal performance. As a...
http://www.chemengonline.com/technical_and_practical/Designing-Shell-and-Tube-Heat-Exchangers-Consider-Two-Phase-Flow_8839.html
January 1, 2012
      Lubricants in rotating machines reduce friction and wear, dissipate heat, protect surfaces, keep out foreign contaminants and remove wear particles. Commonly used liquid lubricants fall into two main categories: mineral (petroleum-based) oils and synthetic oils. Mineral oils are produced by refining crude petroleum. They usually contain trace amounts of some unwanted substances. By...
http://www.chemengonline.com/technical_and_practical/Lubricating-Rotating-Machinery_8840.html
December 1, 2011
Articles about thermal fluid systems often start with a variation of the statement that “thermal fluid systems typically require little ongoing maintenance for the first few years of operation” and then go on to extol the various advantages of indirect thermal-fluid process heating over competitive heating methods, such as direct heat, steam and so on. The corollary to that statement, however...
http://www.chemengonline.com/technical_and_practical/Troubleshooting-Heat-Transfer-Fluid-Systems_8729.html
December 1, 2011
The interior surfaces of your storage tanks are constantly at risk. You undoubtedly walk past a tank and do not give thought to what is happening on the inside, but that is because you trust the interior coating to protect not only the storage vessel, but also the product being stored from corrosion that might occur on the tank. Without a doubt, corrosion is the principal enemy of a storage vessel. It...
http://www.chemengonline.com/technical_and_practical/Preventing-Tank-Corrosion_8756.html
December 1, 2011
The solubility of water in hydrocarbons contained in crude oil is very important. This importance will increase in the future in view of processing, safety, hazard and environmental considerations focusing on product quality and equipment sustainability. The following brief discussion illustrates the importance. Any processing involving the lowering of temperature to values in the range of the freezing...
http://www.chemengonline.com/technical_and_practical/Solubility-of-Water-in-Benzenes-As-a-Function-of-Temperature_8758.html
December 1, 2011
Today’s plant turnarounds bear little resemblance to those of the past: Last-minute preparations and procurements combined with hurried work plans penciled into a notebook often led to undisciplined procedures, incidents and equipment that still operated with defective parts. Those bygone practices have been cleaned up and replaced with clearer processes as turnarounds have become critical to a...
http://www.chemengonline.com/technical_and_practical/Turnarounds-Shorter-Safer-Simpler_8780.html
December 1, 2011
Thermal fluid systems that both heat and cool are often utilized in batch processes. They are also often found in continuous processes where heating is required at one point in the process and cooling (often for the purpose of heat recovery) is required in a different part of the process. Because these systems utilize the same fluid for both the heating and cooling process, they are collectively referred...
http://www.chemengonline.com/technical_and_practical/Thermal-Fluid-Systems-Design-Considerations_8781.html
November 1, 2011
Water and steam are vital components of virtually all plants in the chemical process industries (CPI). And, a very important operation is the treatment of makeup water to produce the purity required for certain applications, most notably for use in heat exchangers and steam turbines. An important consideration in water treatment is that many industrial facilities are, or will soon be, dealing with...
http://www.chemengonline.com/technical_and_practical/Modern-Concepts-in-Makeup-Water-Treatment_8607.html
November 1, 2011
For decades, plant-wide oil-mist systems have been used to lubricate rolling-element bearings in high-speed applications throughout the petrochemicals, textiles, pharmaceuticals, mining and other chemical process industries (CPI). Applications range from small motors to large rotating cylinders and a variety of fluid movers. Plant-wide oil-mist systems provide a centralized way to supply lubricating oil to...
http://www.chemengonline.com/technical_and_practical/Selecting-Oil-Mist-Systems_8615.html
November 1, 2011
To stay on budget, major capital projects often call for aggressive schedules. Engineering, procurement and construction (EPC) contractors often end up using work processes that are not part of an established or standard work procedure. This is especially true when it comes to acquiring materials to support the schedule, particularly for critical paths related to the piping design, supply, fabricate and...
http://www.chemengonline.com/technical_and_practical/Piping-Minimizing-the-Risk-of-Pre-buys_8617.html
November 1, 2011
In today’s climate of increased energy prices and tightening environmental emissions requirements, petrochemicals producers around the world are continuing to focus on optimizing energy consumption at their facilities. Over the past few years, while energy prices have been increasing, petroleum refiners and chemicals producers have made progress toward improved, overall energy performance by...
http://www.chemengonline.com/technical_and_practical/Energy-Benchmarking_8618.html
November 1, 2011
The benefits of field-device diagnostics are often acclaimed in qualitative terms, but on a much lower frequency in quantitative ones. Yet, an attractive cost-benefit analysis is necessary for almost any initiative to make it off the drawing board and into a plant. Even more rare are economic figures that come directly from the process plant engineers (as opposed to a vendor with vested interest in selling...
http://www.chemengonline.com/technical_and_practical/Control-Valve-Diagnostics_8620.html
November 1, 2011
Pinch analysis is a systematic method to maximize energy recovery from process streams entering and exiting process equipment. Using this method, the minimum thermodynamic requirements for hot and cold utilities can be calculated for a process. This is useful to determine areas where savings can be realized and where savings are not available. It is a method that can be used during the design of a process...
http://www.chemengonline.com/technical_and_practical/Energy-Optimization-Using-Pinch-Analysis_8624.html
October 1, 2011
  There are various reasons that make filtering necessary in processes. The raw materials might have impurities that require removal at the start of the process. After the initial mixing to produce the process slurry, the mother liquor could have solids that need a separation process. Unwanted solids could also form by a chemical reaction during the production of the process liquid. The nature of the...
http://www.chemengonline.com/technical_and_practical/Clarifying-Liquid-Filtration_8530.html
October 1, 2011
One of the key components in the operational success of chemical process industries (CPI) facilities is the transfer pump. These pumps must handle a wide variety of materials under a broad range of operating conditions. These diverse operational conditions may include harsh and corrosive environments as well as the following: • Changes in ambient temperatures and other weather conditions, such as...
http://www.chemengonline.com/technical_and_practical/Making-Pump-Maintenance-Mandatory_8535.html
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