Process Equipment and Control

Elemental chlorine is a toxic, yellow-green gas at standard temperatures and pressures. It is supplied as a liquid in high-strength high-pressure steel cylinders, and vaporizes rapidly when released. As the liquid evaporates, its temperature falls and slows the evaporation rate, necessitating the use of a container manifold or vaporizer. 

Chlorine gas can be supplied in cylinders with capacities of 45.4-907.2 kg (100-2000 lb), or in tank cars. The quantities required by small water systems can be purchased from local chemical or swimming pool chemical suppliers. 

There are two basic types of gas chlorinators (a) pressure-operated direct gas feed units and (b) vacuum-operated solution-feed units. Direct gas feed units supply pressurized 

The most sophisticated system includes the basic system plus two scales, a gas mask, a diffuser corporation cock (to allow connection under water line pressure), a flow-pacing chlorine addition system, a flow meter, a booster pump and piping, and a chlorine leak detector. 

A small water treatment system is generally sized to treat water volumes up to at least 0.044 m /s (1 MGD). For small solution-feed systems treating from 9.5 m /d to 0.044 m /s (2500 gpd to 1 MGD), operating and maintenance costs for gas chlorination systems are approximately the same. About 1630 kWh each year is required to run the booster pump and approx 2560 kWh annually is required for the building housing the system, assuming a 58.1-m (625-ft ) building. Maintenance labor cost and material costs for miscellaneous repair of valves, electrical switches, and other equipment replacement cost will be the extra. 

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Throughout these guidelines it is argued that when engineering techniques for the design and assessment of process equipment and control systems are supplemented with human reliability techniques, then performance of both the hardware and humans will be optimized. 

Damage resulting from fires and explosions is minimized by stopping fires or explosions as quickly as possible and also by designing the process equipment (and control centers) to withstand their effects. 

Strigle, R. R, Canadian Process Equipment and Control News, April 1989, p. 66. 

The work to date has led to the formation of a new company (UV Robotics, LLC) that specializes in the integration of UV lamps, robots and other process equipment and controls for end-use applications. [7]... 

The battery limit is a geographic boundary which deflnes the manufacturing area of the process. This includes process equipment and buildings or structures to house it but excludes boilerhouse facilities, pollution control, site infrastructure, etc. 

Scientific Apparatus Makers Association 1140 Coimecticut Avenue, NW Washington, D.C. 20036 Standards for analytical instmments, laboratory apparatus, measurement and test instmments, nuclear instmments, optical instmments, process measurement and control, and scientific laboratory furniture and equipment (see Analytical methods). 

Also, the electronic control-valve device s level of immunity to, and emission of, electromagnetic interference (EMI) can be an issue in the chemical-valve environment. EMI requirements for the control-valve devices are presently mandatory in the European Community but voluntary in the United States, Japan, and the rest of the world. International Electrotechnical Commission (lEC) SOI, Parts I through 4, Electromagnetic Compatibihty for Industrial Process Measurement and Control Equipment, defines tests and requirements for control-device immunity. Immunity and emission standards are addressed in CENELEC (European Committee for Electrotechnical Standardization) EN 50 081-1 1992, EN 50 081-2 1993, EN 50 082-1 1992, and prEN 50 082-2 1994. 

Cyclic nature of Implement mechanical integrity program batch process (e.g.,, Design equipment for easy replacement start/stop, thermal cycling). Possibil- Consider demand of cycling while designing ity of mechanical equipment and controls wear and tear. Possible loss of containment. ... 

Fp) = Friction pressure loss (total) at design basis, for a system, psi, for process equipment and piping, but excluding the control valve... 

Because melts have different properties and there are many ways to control processes, detailed factual predictions of final output are difficult to arrive. Research and hands-on operation have been directed mainly at explaining the behavior of melts or plastics like with other materials (steel, glass, and so on). Modem equipment and controls are overcoming some of this unpredictability. Ideally, processes and equipment should be designed to take advantage of the novel properties of plastics rather than to overcome them. 

Comprehensive reviews of process instruments and control equipment are published periodically in the journal Chemical Engineering. These reviews give details of all the instruments and control hardware available commercially, including those for the on-line analysis of stream compositions (Anon., 1969). Details of process instruments and control equipment can also be found in various handbooks, Perry et al. (1997) and Lipak (2003). 

Simpler plants are friendlier than complex plants because they provide fewer opportunities for error and because they contain less equipment that can cause problems. Often, the reason for complexity in a plant is the need to add equipment and automation to control the hazards. Simplification reduces the opportunities for errors and misoperation. For example, (1) piping systems can be designed to minimize leaks or failures, (2) transfer systems can be designed to minimize the potential for leaks, (3) process steps and units can be separated to prevent the domino effect, (4) fail-safe valves can be added, (5) equipment and controls can be placed in a logical order, and (6) the status of the process can be made visible and clear at all times. 

Once calculations are completed on a depressurization system it will become readily apparent high volumes of gases will be flowing through the header to a flare. In some cases the practicality of simultaneously depressurizing all of the process equipment and vessels will be difficult to accomplish. In these cases a sequential blowdown of the vessels should be considered. Providing for the "worst" vessels first or controlling the system to blowdown the area most affected first are desirable options. 

Develop new less-energetic chemical reaction systems for product manufacture, including alternate catalytic and biological routes where appropriate Emphasize need to develop economically viable inherently safer systems at the research and development stages of new process development Develop new process equipment and strategies for product manufacture using lower inventories of reactive chemicals, error tolerant approaches, and process conditions further from limits of control where appropriate... 

Because these systems can monitor multiple processes, equipment, and infrastructure and then provide quick notification of, or response to, problems or upsets, SCADA systems typically provide the first line of detection for atypical or abnormal conditions. For example, a SCADA system that is connected to sensors that measure specific water quality parameters shows measurements outside of a specific range. A real-time customized operator interface screen could display and control critical systems monitoring parameters. 

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