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July 1, 2011
Gas-liquid reactors in the chemical process industries (CPI) have increasingly been designed to handle larger manufacturing scales. Since gas-liquid reactors can represent substantial capital and operating costs for the user, optimizing mixing and maximizing productivity are critical. The need for efficiency at larger scales places more importance on understanding the physical phenomena of mixing and more...
June 1, 2011
Reciprocating pumps are often used in the chemical process industries (CPI) because of their ability to generate high pressures at low velocities. A subcategory of positive-displacement pumps, reciprocating pumps act through the recipricating motion of a piston, plunger or diaphragm. Such pumps work by way of a connecting-rod-and-crank mechanism with a piston. By nature, reciprocating pumps generate...
May 1, 2011
Pressure measurement in the chemical process industries (CPI) is crucial to many unit operations, and selecting the most effective pressure sensors for a given situation can be complicated by a range of factors. An initial key to selection is establishing an accurate understanding of exactly what is meant when the term “pressure” is used, since there are different types. Other critical...
April 1, 2011
Storing solid materials in hoppers, bins and silos is ubiquitous in the chemical process industries (CPI), as are challenges associated with dispensing them. In many cases, using vessels with steep cones and smooth walls is enough to provide reliable flow. However, it is not always feasible to design and install hoppers with the optimal geometry, and many solids have difficult or variable flow properties...
March 1, 2011
Contact-based temperature sensors, such as thermocouples and resistance temperature detectors (RTDs), have demonstrated accurate and cost-effective operation throughout the chemical process industries (CPI). However, there are many applications and settings where they are simply not practical. In those cases, engineers can turn to a host of non-contact temperature measurement devices, many of which are...
February 1, 2011
The precise monitoring and control of valve position is essential for efficient automation of both discrete and continuous processes. Measurement of valve position provides the data required for the use of advanced control strategies and predictive maintenance algorithms. More effective monitoring of valve position has been an area in which considerable progress has been made in improving the performance...
January 1, 2011
In recent years, a number of factors have further emphasized the importance of solvent selection in the chemical process industries (CPI). These include the increasing regulatory scrutiny leveled on industrial solvents, and an effort by CPI companies to reduce the environmental, health and safety (EHS) impact of their solvent use. In addition, specialized, high-performance solvents are available for some...
December 1, 2010
Most of the more than $100 billion in capital spending and $1.2 trillion in prodution costs spent annually by the chemical process industries (CPI) is committed by decisions made in the early phases of process development and plant design. A more disciplined approach to decision-making that fosters early attention to costs and more thorough consideration of available options has the potential to lower...
November 1, 2010
Measurement of fluids’ viscosity in the chemical process industries (CPI) can represent a useful “product dimension” for manufacturers. Understanding a material’s flow characteristics is valuable in predicting several parameters relevant to many CPI processes, including pumpability, pourability, performance in a dipping or coating operation, ease of handling or processing. The...
October 1, 2010
Crystallization is a key purification technique for various sectors of the chemical process industries (CPI). Several approaches for industrial crystallization have evolved over time and highly specialized crystallizer designs have been developed, especially in long-established industries. Solution crystallization is an important unit operation because the process can generate high-purity products from...
September 1, 2010
The deposition and accumulation of suspended and dissolved particles on membrane surfaces leads to performance loss. Fouling can dramatically reduce the efficiency and economic benefits of a membrane process. The type of fouling and how strongly it appears depends on several parameters, including the following: • Nature of solutes and solvents • Membrane process • Pore-size distribution...
August 1, 2010
OVERVIEW Indirect heating of processes by organic thermal-liquid fluids offers highly reliable operation, and the heat transfer systems are generally treated as low-maintenance utilities. Occasionally, the heat transfer fluid can become contaminated, resulting in the formation of sludge particles, or other sources of dirt can infiltrate the system. This contamination can cause operational problems. The...
July 1, 2010
Reduction of greenhouse gas (GHG) emissions continues to be a major issue in national and international public policy, as well as a major focus for companies in the chemical process industries (CPI). Many countries are considering systems that place a price on GHG emissions through a carbon cap-and-trade system, for example. In an environment where GHG emissions have a given price, certain energy...
June 1, 2010
In a distillation column tray, vapor passes upward through liquid that is flowing across a horizontal perforated plate. Vapor passing through the perforated plate forms a two-phase mixture with the liquid and enables mass transfer contacting. This mixture is typically quite turbulent. Tray design must allow the turbulent liquid to fall away from the rising vapor in the space above the tray, while also...
May 1, 2010
Burners are critical for the successful operation of industrial furnaces. Presented here is a set of equations that can be used to calculate characteristics of burner operation, including flame length, flame diameter, ignitability and flameout conditions. Equations are based on pre-mix burners operating at atmospheric pressure and firing natural gas only. Premix burners create short and compact flames...
April 1, 2010
Mechanical seals play a pivotal role in the chemical process industries (CPI). As the sealing interface between rotating process equipment and the materials contained inside, these devices prevent product leakage and fugitive emissions, while permitting process machines, pumps and compressors to operate at ever-increasing pressures, vacuums, temperatures and speeds. Even the most basic mechanical seal is a...
March 1, 2010
Steam tracer lines are designed to maintain the fluid in a primary pipe at a designated uniform temperature. In most cases, these tracer lines are used outdoors, which makes ambient weather conditions a critical consideration. The primary purpose of steam traps on tracer lines is to retain the steam until its latent heat is fully utilized, and then discharge the condensate and non-condensable gases. As is...
February 1, 2010
Pumps are essential equipment in the chemical process industries (CPI). Given the imperatives to reduce production costs and maximize energy efficiency, pump selection is crucial. Knowledge of pumping basics, along with the fluid characteristics for a particular application can help engineers make the best choice. While the majority of pumps in use in CPI plants are kinetic energy pumps (the largest...
January 1, 2010
Because of the behavior of materials under vacuum, including lowered boiling points, low-pressure operations are useful tools in chemical processing, as well as in research and development and manufacturing. Areas where a vacuum system is necessary or useful include the following: • Separating liquids • Processing temperature-sensitive materials • Preventing unwanted chemical reactions...
December 1, 2009
Installed gain graphs can help improve the selection of control valves for chemical processing. The graphs are plotted to analyze together control-valve flow characteristics and process-system flow characteristics, and better illustrate the relationship between a control valve and the system. Predicting installed gain can help to increase controllability of the system and help avoid oversized valves...
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