Pilot plant testing, chemical processing

Process R D literature review patent review research reports bench scale pilot reports sketch of flow sheet chemicals and their characteristics chemical reactions and interactions thermodynamics physical properties preliminary process concept Laboratory screening and testing for chemicals (toxicity, instability, explosibility) for reactions (explosibility) for impurities Pilot plant tests... 

Other services For chemicals, refer to Section 21.4 for guidance on materials selection for common chemicals. For other chemicals, refer to the available literature. For proprietary technologies, follow the guidance of the process licensor. Such guidance is always subject to review for compliance with safety and design life requirements. Plant experience and pilot plant testing, in some cases, will indicate suitable materials. 

Slow decay of adsorbents due to irreversible adsorption of trace conponents or thermal deactivation of active sites is also common. When this occurs, operating conditions must be adjusted accordingly. Because of this poisoning, adsorption processes, which use surface phenomena, are often much more sensitive to trace chemicals than distillation and other separation techniques that rely on bulk properties. An occasional wash step or extreme regeneration step maybe needed. A short life for the sorbent, which can be a problem in biological operations, often makes the process uneconomical. Long-term pilot plant tests with the actual feed from the plant are useful to determine the seriousness of these problems. 

Most chemical plant processes are complex. Materials of construction for process equipment and piping must be selected with care to assure corrosion-free operation of those plants. In a well designed plant, materiids selection is based on a number of factors prior service history, field in-plant corrosion tests, pilot plant corrosion tests and laboratory corrosion tests, in that relative order of usefiihiess. often, actual service history regarding materials performance is not available because plants kept poor records, plant personnel were not trained to evaluate corrosion failures, or, in the case of new processes, because there is no service history. The same can be said for field in-plant corrosion tests. Pilot plant testing is usually the best alternative in such cases, but such facilities are typically operated only for short runs and are not well suited for gathering long-term corrosion performance data. 

Pyrolysis Of the many alternative chemical conversion processes that have been investigated, pyrolysis has received the most attention. Pyrolysis has been tested in countless pilot plants, and many full-scale demonstration systems have been operated. Few attained any longterm commercial use. Major issues were lack of market for the unstable and acidic pyrolytic oils and the char. 

For a new process plant, calculations can be carried out using the heat release and plume flow rate equations outlined in Table 13.16 from a paper by Bender. For the theory to he valid, the hood must he more than two source diameters (or widths for line sources) above the source, and the temperature difference must be less than 110 °C. Experimental results have also been obtained for the case of hood plume eccentricity. These results account for cross drafts which occur within most industrial buildings. The physical and chemical characteristics of the fume and the fume loadings are obtained from published or available data of similar installations or established through laboratory or pilot-plant scale tests. - If exhaust volume requirements must he established accurately, small scale modeling can he used to augment and calibrate the analytical approach. 

Scale-up techniques for using the results of pilot plant or bench scale test w ork to establish the equivalent process results for a commercial or large scale plant mixing system design require careful specialized considerations and usually are best handled by the mixer manufacturer s specialist. The methods to accomplish scale-up will vary considerably, depending on whether the actual operation is one of blending, chemical reaction tvith product concentrations, gas dispersions, heat transfer, solids suspensions, or others. 

It is reported here that DuPont is planning to launch a pilot plant in 2000, to test a new, patented process for chemically recycling nylon 6/6 resin. Full details are given of the process, called ammonolysis. 

This article discusses a pilot plant to test the feasibility of a chemical recycling process for PU foam developed by ICI. The plant, which is in Hertfordshire, UK, will be opened in October 1998. It uses split-phase glycolysis for recycling. Full details are given. 

What is very important in process development is the personnel overlap when changing the scale of the process. The head of the team that is to continue the development of a process should be involved in the research on smaller scale. Also, an important member or head of the team in the smaller scale research should participate in the further step(s) of process development. Often, a parallel operation of teams is required instead of operation in series. A pilot plant, mostly composed of existing equipment items in a company, is often required as the final step in process development. A verification of procedures and models is usually not necessarily the main objective of pilot studies. The most common reason for manufacture at pilot scale is the production of kilograms of the product for market purposes and toxicity tests. A close interaction between chemists and chemical engineers is necessary at all stages of process development. 

If the product is to be used for pharmaceuticals the GMP rules must be obeyed during plant operation. All chemicals to be tested in clinical studies with humans must be prepared according to GMP. This leads to very detailed documentation since if you haven t documented it, you haven t done it . All procedures for manufacturing and changes in procedures are subject to approval by quality control departments. This decreases the flexibility in process development. Products that are contaminated too much must be reprocessed according to the GMP guidelines. All equipment to be used in the pilot plant must be validated before use. 

As noted in Chapter 1, the priorities in batch processes are often quite different from those in large-scale continuous processes. Particularly when manufacturing specialty chemicals, the shortest time possible to get a new product to market is often the biggest priority (accepting that the product must meet the specifications and regulations demanded and the process must meet the required safety and environmental standards). This is particularly true if the product is protected by patent. The period over which the product is protected by patent must be exploited to its full. This means that product development, testing, pilot plant work, process design and construction should be fast tracked and carried out as much as possible in parallel. 

In the design of an industrial scale reactor for a new process, or an old one that employs a new catalyst, it is common practice to carry out both bench and pilot plant studies before finalizing the design of the commercial scale reactor. The bench scale studies yield the best information about the intrinsic chemical kinetics and the associated rate expression. However, when taken alone, they force the chemical engineer to rely on standard empirical correlations and prediction methods in order to determine the possible influence of heat and mass transfer processes on the rates that will be observed in industrial scale equipment. The pilot scale studies can provide a test of the applicability of the correlations and an indication of potential limitations that physical processes may place on conversion rates. These pilot plant studies can provide extremely useful information on the temperature distribution in the reactor and on contacting patterns when... 

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. 

The data obtained from small-scale continuous operations will be required to determine whether the process should be investigated on a larger scale, such as a pilot plant. These data should be sufficient to draw a conceptual flow sheet, which will include a number of stages for extraction, scrubbing [10], and stripping the flow rates, size and type of equipment, and the various parameters considered earlier in this chapter. Another important aspect should also be considered in the continuous test work, and that is chemical analysis of both the aqueous and organic phases for their various components. 

The conversions, selectivities, and kinetics are ideally obtained in a small batch reactor, the operating conditions and catalyst formulation are determined from a bench-scale continuous reactor, the process is tested and optimized in a pilot plant, and finally the plant is constructed and operated. While this is the ideal sequence, it seldom proceeds in this way, and the chemical engineer must be prepared to consider aU aspects simultaneously. 

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