Plant design and controls

Service flow rate Operating pressure Operating temperature Bed pressure drop Backwash flow rate Rinse flow rate Valve sequencing 

The RO unit design is based on meeting the specified product water quality and flux. RO unit service run is based on permeate conductivity (% rejection), productivity 

Typically, RO systems are designed with the following general conditions for safe and  

Process condition Open valves Prime mover 

Service feed/product/reject OV-161-1/ MV-161-3/MV- RO high-pressure 

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Many of the incidents occurred due to a combination of causes and validly could be assigned to several categories, but for simplicity they have been assigned here to one category only — the prime (or prima facie) cause. As will be appreciated, the prime cause is often merely the symptom of a more deep-rooted cause — for example, lack of a systematic approach to reaction hazards assessment, no proper basis of safety, inadequate attention to plant design and control, and poor or absent operating procedures, instructions and training. 

The Engineering models were developed early on as they were used during the detailed engineering phase for validation of the plant design and control schemes. They were used for the development of APC and may in future be used for fiirther optimisation. 

G.4 Interaction of Plant Design and Control System Design Summary... 

G.4 INTERACTION OF PLANT DESIGN AND CONTROL SYSTEM DESIGN... 

The TAME reactive distillation system with a two-column methanol recovery system was successfully simulated in Aspen Dynamics. The system features two recycles (methanol and water) and three feedstreams (C5, methanol, and water). The system is essentially a ternary system with inerts, but the complex vapor-liquid equilibrium results in the formation of azeotropes that result in losses of methanol out of the top of the reactive column with the inerts. Therefore, a methanol recovery system must be included in the plant design and control. 

A recent addition to the model-based tuning correlations is Internal Model Control (Rivera, Morari, and Skogestad, Internal Model Control 4 PID Controller Design, lEC Proc. Des. Dev., 25, 252, 1986), which offers some advantages over the other methods described here. However, the correlations are similar to the ones discussed above. Other plant testing and controller design approaches such as frequency response can be used for more complicated models. 

There are four overall guidehnes that analysts should keep in mind. They must recognize the difficulties associated with the limited number and accuracy of the data, overcome the plant operation mythologies, overcome the designers and controllers biases and, finally, override the analysts own prejudices. The following four overall guidelines assist in overcoming the hurdles to proper plant performance. 

Plant-performance analysis reqmres the proper analysis of limited, uncertain plant measurements to develop a model of plant operations for troubleshooting, design, and control. 

CIA 1990. A Approach to the Categorization of Process Plant Hazard and Control Building Design. Prepared by Working Group 3 of the Major Hazards Steering Group. Issued by the Safety Committee of the Chemical Industry Safety and Health Council of the Chemical Industries Association, Eondon. 

COD Design of treatment plant Legislation and controls Oxidation by acid dichromate... 

An Approach to the Categorisation of Process Plant Hazard and Control Building Design (1990)... 

Additional pollution control devices beyond the scrubbers, cyclones, and baghouses that are an integral part of the plant design and operations are generally not required for mixed fertilizer plants. 

Englund, S. M. (1993). Process and Design Options for Inherently Safer Plants. Prevention and Control of Accidental Releases of Hazardous Gases, ed. V. M. Fthenakis, 9-62. New York Van Nostrand Reinhold. 

Huang, Y. L., and Fan, L. T. (1995). Intelligent process design and control for in-plant waste minimization. In Waste Minimization Through Process Design (A. P. Rossiter, eds.), pp. 165-180. McGraw Hill, New York. 

Separate reheat batteries may be placed in branch ducts where one plant supplies both a main area calling for cooling and an auxiliary room without heat load. Correct rh in the auxiliary rooms results (only) if it is correctly controlled in the main room and they require the same dry bulb temperature. While wasteful of energy, it simplifies the plant design and may be found to use fewer resources. 

Boric acid [B(OH)3] is employed in primary coolant systems as a soluble, core reactivity controlling agent (moderator). It has a high capture cross-section for neutrons and is typically present to the extent of perhaps 300 to 1,000 ppm (down from perhaps 500 to 2,500 ppm 25 years ago), depending on nuclear reactor plant design and the equilibrium concentration reached with lithium hydroxide. However, boric acid may be present to a maximum extent of 1,200 ppm product in hot power nuclear operations. 

Chemical engineering is no longer confined to purely physical processes and the unit operations, and a number of important new topics, including reactor design, automatic control of plants, biochemical engineering, and the use of computers for both process design and control of chemical plant will be covered in a forthcoming Volume 3 which is in course of preparation. 

A consideration of dynamics should be factored into the design of a plant at an early stage, preferably during pilot-plant design and operation. It is often easy and inexpensive in the early stages of a project to design a piece of process equipment so that it is easy to control. If the plant is designed with little or no consideration of dynamics, it may take an elaborate control system to try to make the most of a poor situation. 

United Kingdom Chemical Industries Association. 1993. An Approach to Categorization of Process Plant Hazards and Control Building Design. 

Based on the above performance concerns, Eqs. (22.22) and (22.24), an L2-gain robust controller is designed such that the plant disturbance d and sensor noise 6 have minimum effect on the plant dynamics and control actions. In an energy sense, this can be specified by... 

Safety and control in high pressure plant design and operation 405... 

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