Pilot facilities and pilot plants in the process industry

Germany has a densely occupied and highly specialised supplier segment for pilot facilities and pilot-plant equipment. Historically it emerged from machine and plant engineering for process technology. The suppliers can be divided primarily into three categories:

Specialised apparatus and component builders: these manufacturers focus on specific unit operations such as mixing, dispersing, kneading, size reduction, classifying, drying, granulating, coating and extruding as well as thermal separation processes, and offer laboratory and pilot-plant units in scalable series for them. Typical systems include intensive, ploughshare, conical and twin-shaft mixers, pilot-plant mills (e.g. ball, jet, impact and agitator bead mills), fluidised bed, spray, vacuum contact and belt dryers, twin-screw extruders at pilot-plant scale as well as filtration, distillation and crystallisation plants.

These solutions address the construction, chemical, pharmaceutical, food, polymer and battery industries, among others, and permit scale-up through geometrically and process-technically similar series.

Turnkey plant builders for pilot and mini-plant systems design and realise turnkey, often modular pilot lines (e.g. as skid assemblies) that map the entire process path from raw material handling through reaction, processing and forming to the end product. They offer pilot, laboratory and mini-plant systems with integrated process technology and automation for the chemical, pharmaceutical, biotechnological and other industries.

Engineering service providers and manufacturers with their own pilot plant have pilot plants and trial centres that can be used as "capacity as a service". Customers draw on existing pilot infrastructure and carry out feasibility studies, trial series and scale-up tests without having to invest in hardware themselves. Various laboratory and pilot facilities for mixing, reaction, separation and drying processes are often available, complemented by process analysis and automation.

Pilot plants of research institutions

Alongside industrial manufacturers, Fraunhofer institutes, universities and industry-oriented research institutions also operate their own pilot plants. These can be used for contract trials, joint development projects and scale-up studies. This is often a sensible preliminary step or an alternative to investing in one's own pilot infrastructure.

The importance of the pilot plant for formulation development

The pilot plant forms the critical link between laboratory scale (grammes to kilogrammes) and industrial production (tonne scale). It allows formulations to be validated under near-production conditions, with central physical influencing variables (e.g. shear forces, heat transfer coefficients, residence time and flow behaviour) controlled and varied systematically.

This makes it possible to:

• reduce the risk of faulty batches in the large-scale plant
• quantify raw material efficiency and yields
• assess energy indicators and operating costs at an early stage
• determine technological limits and operating windows reliably

The data obtained in the pilot plant form the basis for robust scale-up concepts and investment decisions.

Process engineering requirements for modern pilot facilities

Modern pilot facilities for formulation development and process optimisation are characterised by high flexibility, modularity and data density. Typical features are:

• Modularity and variant capability: interchangeable process modules (e.g. different agitators, nozzles, separation stages or filter media) allow rapid adaptation to different viscosities, particle sizes, reaction kinetics or product types. Modular process zones permit switching between process operations (e.g. granulating, drying, coating or reacting) within one plant.
• Integration of in-line and at-line measurement technology: spectroscopic in-line measurement, particle size analysis, conductivity as well as pH, temperature and pressure sensors enable real-time monitoring of product and process quality by means of process analytical technology (PAT). The high density of instrumentation supports statistical design of experiments and the development of robust process models.
• Hygienic design and regulatory conformity: in life science and food applications the plants meet the GMP, FDA, hygienic design and ATEX requirements. Cross-contamination during formulation changes is thereby excluded and safety as well as product quality are assured.

Open interfaces and data integration

Modern systems offer open interfaces for integration into control systems, production systems or laboratory systems and facilitate the recording, evaluation and archiving of trial data.

Transfer from the pilot phase into production (scale-up)

Scale-up is based on the application of similarity theory. Chemical and process engineers use characteristic dimensionless numbers (e.g. Reynolds number, Newton number, Archimedes number) and further characteristic values in order to transfer the optimum process parameters determined in the pilot plant to larger volumes.

The objectives of scale-up are:

• maintaining geometric, kinematic and thermal similarity between pilot plant and production plant
• ensuring constant product quality despite increasing throughput
• minimising adaptation effort, start-up times and reject material at the large-scale plant

Use of the pilot-plant data

The data obtained in pilot-plant operation feed into design calculations, the selection of apparatus, safety considerations and economic assessments.

The role of automation in pilot-plant systems

The automation of modern pilot facilities goes far beyond simple control functions and is a central enabler of systematic process optimisation.

Data acquisition and design of experiments (DoE): programmable logic controllers (PLC) and higher-level systems with integrated database connections record process and quality data continuously. This forms the basis for DoE approaches in which parameter combinations are varied systematically and evaluated statistically.

The data collected allow correlation analyses between process parameters and quality characteristics. On this basis, process models and increasingly digital twins are created. With these, future process adjustments can first be simulated and optimised virtually and then implemented in the pilot plant or in production.

Scalable automation concepts

Through the use of standardised interfaces, control platforms and function blocks, automation concepts can be transferred from the pilot plant to production plants relatively easily. This shortens scale-up and increases the reusability of know-how.

Selection criteria when choosing a manufacturer

When selecting a manufacturer of pilot facilities and pilot-plant equipment, technical decision-makers should examine the following criteria in particular:

• scale-up capability and similarity between pilot plant and large-scale plant
• the supplier's industry and process expertise (e.g. chemicals, pharmaceuticals, food, polymers, batteries)
• GMP/ATEX conformity and hygienic design depending on the target application
• density of instrumentation, PAT equipment and data connectivity
• modularity and expandability of the plant to cover different formulations and processes
• availability of trial centres/pilot plants for feasibility studies before investment decisions

The combination of a suitable supplier category, an appropriately dimensioned pilot facility and data-based process development creates the basis for robust, scalable and economic production.