Operational considerations batch plants

In the analysis, synthesis and optimization of batch plants complexity arises from the various operational philosophies that are inherent in time dependent processes. In a situation where the intermediate is allowed to wait in the same unit from which it is produced until the next unit is available, the operational philosophy is commonly known as no intermediate storage (NIS) operational philosophy. This philosophy is depicted in Fig. 1.3. NIS operational philosophy is usually adopted if operational space is of essence, since intermediate storage tanks can occupy considerable area. 

A mathematical approach for optimization of energy use in heat integrated multipurpose batch plants has been presented and tested in a case study. The results have shown that heat integration with heat storage considerations can result in energy savings of more than 75%, compared to standalone operation that relies solely on... 

Very extensive laboratory work on all phases of the use of catalytic reduction to produce both aliphatic and aromatic amines has been reported in the literature. Studies have been carried out on many types of catalysts, catalyst supports, promoters and poisons, solvents, temperatures, pressures, and equipment. Considerable pilot-plant work and engineering studies have been undertaken and a number of commercial installations built for batch catalytic reduction and for continuous catalytic reduction. Commercial installations are now in operation for the catalytic reduction of nitro compounds and nitriles. 

Another basic consideration is whether crystallization is best carried out on a batch basis or on a continuous basis. The present tendency in most processing plants is to use continuous equipment whenever possible. Continuous equipment permits adjusting of the operating variables to a relatively fine degree in order to achieve the best results in terms of energy usage and product characteristics. It allows the use of a smaller labor force and results in a continuous util-... 

The design of production plants for the manufacture of the three categories of product varies considerably. Fine chemicals are usually produced in batch reactors, which may also be used for the production of a variety of similar products. Fine chemicals usually have demanding product quality specifications and, consequently, a significant fraction of the production costs are involved in product purification and testing. Intermediate volume chemicals have less rigorous quality specifications than fine chemicals and are usually manufactured in product-specific-plants, either as batch or continuous flow processes. Bulk chemical production plants usually operate continuous flow processes... 

The fine chemicals business is characterized by a small volume of products manufactured. Therefore, batch production predominates and small-scale reactors are used. The need to implement fine chemistry processes into existing multiproduct plants often forces the choice of batch reactors. However, safety considerations may lead to the choice of continuous processing in spite of the small scale of operation. The inventory of hazardous materials must be kept low and this is achieved only in smaller continuous reactors. Thermal mnaways are less probable in continuous equipment as proven by statistics of accidents in the chemical industries. For short reaction times, continuous or semicontinuous operation is preferred. 

In co-operation with a German chemical company, a recipe-driven batch process was modelled and simulated using PPSiM. In the simulation study, different pipeless plant scenarios were tested and evaluated. The plant under consideration produces a set of consumer care products. 

During the development of a chemical process, a choice must be made regarding the type of reactor to be used on a plant scale. Some theoretical considerations and their practical impact on reactor issues are presented here. Choosing the right type of reactor can indeed improve the safety of the process. The considerations are reflected as well in the mode of operation. Reactors are characterized by type of operation (i.e., batch, semi-batch, and continuous). 

The RC1 is an automated laboratory batch/semi-batch reactor for calorimetric studies which has proven precision. The calorimetric principle used and the physical design of the system are sound. The application of the RC1 extends from process safety assessments including calorimetric measurements, to chemical research, to process development, and to optimization. The ability of the RC1 to generate accurate and reproducible data under simulated plant scale operating conditions may result in considerably reduced testing time and fewer small scale pilot plant runs. 

Timer-controlled systems are simple, low-cost systems which involve timing of flow through an orifice. Most include a sight glass or other means of checking the amount batched. A number of variables, such as changes in power supply, constriction of the measuring orifice and increased viscosity of the admixture can introduce considerable error. Timer-controlled units must be recalibrated frequently, and the plant operator must be alert to verify the proper admixture dose by observation of the calibration tube. They have been successfully used with... 

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