Pilot Scale Production

[Leroy Turcios]

Apilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology. The knowledge obtained is then used for design of full-scale production systems and commercial products, as well as for identification of further research objectives and support of investment decisions. Other (non-technical) purposes include gaining public support for new technologies and questioning government regulations.[1] Pilot plant is a relative term in the sense that pilot plants are typically smaller than full-scale production plants, but are built in a range of sizes. Also, as pilot plants are intended for learning, they typically are more flexible, possibly at the expense of economy. Some pilot plants are built in laboratories using stock lab equipment, while others require substantial engineering efforts, cost millions of dollars, and are custom-assembled and fabricated from process equipment, instrumentation and piping. They can also be used to train personnel for a full-scale plant. Pilot plants tend to be smaller compared to demonstration plants.

A word similar to pilot plant is pilot line.[2] Essentially, pilot plants and pilot lines perform the same functions, but 'pilot plant' is used in the context of (bio)chemical and advanced materials production systems, whereas 'pilot line' is used for new technology in general. The term 'kilo lab' is also used for small pilot plants referring to the expected output quantities.[3]

If a system is well defined and the engineering parameters are known, pilot plants are not used. For instance, a business that wants to expand production capacity by building a new plant that does the same thing as an existing plant may choose to not use a pilot plant.

Additionally, advances in process simulation on computers have increased the confidence of process designers and reduced the need for pilot plants. However, they are still used as even state-of-the-art simulation cannot accurately predict the behavior of complex systems.

As a system increases in size, system properties that depend on quantity of matter (with extensive properties) may change. The surface area to liquid ratio in a chemical plant is a good example of such a property. On a small chemical scale, in a flask, say, there is a relatively large surface area to liquid ratio. However, if the reaction in question is scaled up to fit in a 500-gallon tank, the surface area to liquid ratio becomes much smaller. As a result of this difference in surface area to liquid ratio, the exact nature of the thermodynamics and the reaction kinetics of the process change in a non-linear fashion. This is why a reaction in a beaker can behave vastly differently from the same reaction in a large-scale production process.

After data has been collected from operation of a pilot plant, a larger production-scale facility may be built. Alternatively, a demonstration plant, which is typically bigger than a pilot plant, but smaller than a full-scale production plant, may be built to demonstrate the commercial feasibility of the process. Businesses sometimes continue to operate the pilot plant in order to test ideas for new products, new feedstocks, or different operating conditions. Alternatively, they may be operated as production facilities, augmenting production from the main plant.

The differences between bench scale, pilot scale and demonstration scale are strongly influenced by industry and application. Some industries use pilot plant and demonstration plant interchangeably. Some pilot plants are built as portable modules that can be easily transported as a contained unit.

For continuous processes, in the petroleum industry for example, bench scale systems are typically microreactor or CSTR systems with less than 1000 mL of catalyst, studying reactions and/or separations on a once-through basis. Pilot plants will typically have reactors with catalyst volume between 1 and 100 litres, and will often incorporate product separation and gas/liquid recycle with the goal of closing the mass balance. Demonstration plants, also referred to as semi-works plants, will study the viability of the process on a pre-commercial scale, with typical catalyst volumes in the 100 - 1000 litre range. The design of a demonstration scale plant for a continuous process will closely resemble that of the anticipated future commercial plant, albeit at a much lower throughput, and its goal is to study catalyst performance and operating lifetime over an extended period, while generating significant quantities of product for market testing.

In the development of new processes, the design and operation of the pilot and demonstration plant will often run in parallel with the design of the future commercial plant, and the results from pilot testing programs are key to optimizing the commercial plant flowsheet. It is common in cases where process technology has been successfully implemented that the savings at the commercial scale resulting from pilot testing will significantly outweigh the cost of the pilot plant itself.

Custom pilot plants are commonly designed either for research or commercial purposes. They can range in size from a small system with no automation and low flow, to a highly automated system producing relatively large amounts of products in a day. No matter the size, the steps to designing and fabricating a working pilot plant are the same. They are:

These studies, ranging from controlled lab environments to real-world commercial setups, play crucial roles in refining and optimising processes, technologies, and treatment methods. Each has its advantages and limitations.

Such studies are essential preliminary steps before progressing to larger-scale programs like pilot or full-scale plants. The primary goal? To refine and optimise a particular process, technology, or treatment method by analysing its feasibility.

Engineers and scientists value the controlled conditions in these studies, allowing them to introduce and manipulate various variables. If in a lab, they may manipulate temperature and pH to metal presence.

For starters, the cost-effectiveness of laboratory-scale studies is unparalleled. Conducted on a smaller scale, they utilise lesser quantities of materials and equipment, making them a preferable choice for preliminary research.

Fast: In the high-paced world of scientific research, time is of the essence. These studies, therefore, are not only efficient in resources but also in time. They can be conducted, analysed, and refined in a fraction of the time it might take to set up and run a full-scale program.

Safety: he safety in a laboratory-scale study is heightened. By keeping the experiments contained, risks associated with larger scales, such as extensive plant treatments, are minimised.

Small Sample Size: Another bone of contention is the small sample size. In R&D settings, while you might accelerate results and reduce costs using laboratory-scale, the statistical strength of the results may not be robust.

These studies provide valuable data that can be integral to reducing the risk associated with scale-up to large-scale production. For example, a catalyst that might work wonders in a beaker might face challenges when integrated into full-scale operational systems.

So, when considering the scale-up of new technology or new products, diving deep into pilot studies can help determine the feasibility and reliability of the process, ensuring an optimised transition from the bench scale to the real world operations.

Lower Cost: they provide a real-world testing ground without the overwhelming costs of commercial plant operations. New products, technologies, and process developments can be introduced, refined, and optimised in pilot plants before a full-scale rollout.

Best For Feasibility Study: Moreover, pilot scale testing allows for the sampling and study of a wider range of operational variables, ensuring the feasibility and reliability of the process.

In essence, a pilot scale study can serve as a roadmap, guiding industries from the bench scale of the lab to the bustling activity of production facilities, minimising costs, and ensuring efficient scale-up. Pilot scale study is an indispensable tool in the modern R&D toolkit.

For instance, certain catalysts or organic compounds, which operate optimally in the controlled environment of a pilot plant, might show varied results when exposed to the dynamics of full-scale operations.

Less Realistic Sample Size: While pilot scale testing offers a snapshot of potential large-scale outcomes, the sample size and experimental conditions might make it difficult to capture the full spectrum of operational variabilities.

One of the main differences between pilot and full-scale studies is the sheer magnitude. In a full-scale study, variables such as pipe sizes, hydraulic rates, and concentrations are not just theoretical values from a laboratory-scale experiment but tangible factors with direct implications on profitability and utility.

This larger scale study allows for extensive sampling, capturing a wider range of operational variabilities. It aids in refining the system, reducing the risk associated with scale-up, and ensuring the reliability of the process.

Realism: Full scale study is typically conducted in commercial plants, allowing researchers to experience the nuances and challenges of large-scale production, beyond the controlled environment of a lab.

Captures More Variables: A full-scale study integrates all aspects of the process, capturing a wider range of operational variabilities. Its larger scale facilitates extensive sampling, providing valuable data to optimise process development.

Ability To Refine Processes Under Actual Conditions: Another significant advantage is its ability to refine processes under actual experimental conditions, ensuring the viability of the process for startup and deployment of new products.

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