Archives :: Facts At Your Fingertips
March 1, 2014
Effective level measurement in the chemical process industries (CPI) helps maintain material inventory at economic quantities, improves product quality and maximizes plant output by avoiding spills and process upsets. When they are incorrectly matched to their application, level-measurement devices can contribute to lower quality and poorer process consistency. No single level-measurement technology is...
February 1, 2014
Workers in the chemical process industries (CPI) can wear chemical protective clothing to protect themselves from exposure to potentially hazardous chemicals in the form of vapor, liquid and solid particles. While chemical protective clothing has not been regulated to the extent that safety glasses, hard hats and some other forms of personal protective equipment (PPE) have been, an international standard...
January 1, 2014
Dust is a critical consideration in the chemical process industries (CPI) from both a process safety standpoint — as a potential fire and explosion hazard — and from an occupational safety standpoint — as a potential worker exposure hazard. Reinforcing basic concepts about dust behavior and properties can help reduce the risks. Health hazards Airborne particles are solids suspended in the...
December 1, 2013
Testing in filtration processes is critical for determining the properties of solids being filtered and the ease or difficulty of the filtration. In addition, laboratory testing is important in specifying filter media, filter aids, filter area, cake space needed and cake discharge techniques. Experimental data gathered in the laboratory help in the design of the full filtration system needed for...
November 1, 2013
Calculating volumes of solids in piles as they are poured into various shaped containers can be important information for solids-handling applications. The following set of equations represents guidance to help determine solids volume in these cases. Solids in containers Solids fed through a nozzle into a cylindrical or rectangular silo normally form a partial cone of a complex shape when the material is...
October 1, 2013
Optimizing fan performance can help plants reach overall process efficiency goals. The cost of powering fans and ventilators in the chemical process industries (CPI) is significant. For example, ventilation and air-pollution control systems can account for over a quarter of energy a facility’s consumption. Fan performance is typically estimated by using a graph that shows the different pressures...
September 1, 2013
Chemical processing equipment made from thermoplastics can have distinct advantages for equipment corrosion, fluid contamination and flame retardancy. When purchased in the form of heavy-gauge sheets, these thermoplastics can be machined, fabricated and formed into a virtually unlimited variety of process equipment components that may address chemical processing challenges that other materials cannot. The...
August 1, 2013
The management of process plants requires understanding and applying the fundamental tenets of safe design, construction and operation of facilities. This overview summarizes best practices that have been developed to ensure the safest possible use of DP:DPO (diphenyl–diphenyl oxide) eutectic heat-transfer fluids. A review of the concepts necessary for effectively maintaining a leak-tight...
June 1, 2013
Dry, granular solids can be conveyed in a number of ways. Two common devices for transporting granular solids are the angular-pitch vibrating conveyor and the horizontal differential-motion conveyor. The variability in the design and performance between the two types stems from the differences in the kind of motion required to move the mass in one direction. The most significant difference between the two...
May 1, 2013
Minimizing process variability is an important component of a plant’s profitability. The performance of control valves within process control loops has a significant impact on maintaining consistent processes. This refresher outlines some of the important aspects of control-valve performance, including parameters of both the static response and the dynamic response. Static response A valve’s...
April 1, 2013
The detection of gases in plant environments has a critical and wide-ranging role in the chemical process industries (CPI). Among the major applications of gas detection are limiting personnel exposure to hazardous chemicals, preventing explosive atmospheres, protecting the environment and identifying leaks in process equipment. Table 1 summarizes the main reasons for gas monitoring. All CPI workers should...
March 1, 2013
Temperature is among the most critical measurements in the chemical process industries (CPI) for operating safe and efficient processes. Because even a small error in temperature can lead to expensive consequences, accurate and reliable monitoring of temperature is required. Thermowells The most accurate temperature measurements occur when the sensor is in direct contact with the process fluid being...
February 1, 2013
Supplying steam that meets process needs while protecting steam-system components, such as boilers and steam turbines (Figure 1), against scale, fouling and corrosion, requires purified feedwater (condensate plus makeup water). Depending on the steam pressure required, the specific approach of the water treatment may be shifted to account for a variety of issues. For example, caustic corrosion and...
January 1, 2013
Non-chemical water treatment methods generally utilize electricity to prevent scale formation, mitigate corrosion and control microbial growth. When properly applied, non-chemical water-treatment technologies help plants reduce chemical consumption, minimize waste and possibly save water and energy. The following descriptions outline several types of non-chemical water-treatment methods. Magnetic fields...
December 1, 2012
Wet fluegas desulfurization (FGD), also known as wet-scrubbing, is a popular pollution-abatement technique for removing acid gases, such as SO2 and HCl from fluegas produced during coal-fired power generation and industrial combustion processes. Wet scrubbing is used in association with power generation, thermal oxidizers, kilns, incinerators, boilers, foundries and other combustion units. Also...
November 1, 2012
For most solids-processing operations in the chemical process industries (CPI), particle-size reduction and screening (classification) to achieve the desired particle-size are required, since processes rarely produce the desired size directly. When designing processes, selecting equipment and looking for ways to increase efficiency, CPI engineers must understand the size-reduction behavior of the solid...
October 1, 2012
Fans and blowers are common in air-handling and movement systems used in the chemical process industries (CPI). Two major uses of fans and blowers are in pneumatic conveying systems and in ventilation and air-pollution-control systems. Powering fans and blowers can contribute significantly to costs, and their efficient operation can be affected by the way plant operators select and run their systems...
September 1, 2012
Sparging refers to the process of injecting a gas through a diffuser into a liquid phase. It is used in both physical and chemical process applications. In physical process applications, the gas is used to either dissolve gas into liquid (such as aeration and carbonation) or to remove contaminants from the liquid phase (such as oxygen stripping, volatile organic compound stripping and water stripping). In...
August 1, 2012
The main function of the expansion tank in a heat-transfer system is to allow space for the heat-transfer fluid to expand as it is heated. A properly designed, installed and maintained expansion tank will support longer fluid and equipment life, safe operation and easier maintenance. Configuration The expansion tank is best located at the highest point in the system to provide a positive pressure head to...
July 1, 2012
Automated systems for batch weighing can improve overall product quality by raising the accuracy and consistency of the mixture compared to what can be achieved with the manual addition of pre-weighed bags. Automated batch-weighing systems integrate load cells with connections, valves, relay hardware and process control software. These systems control one or more pieces of feed equipment that deliver...
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