For decades, the pharmaceutical and chemical industries have manufactured products using batch production methods. With batch production, a predetermined weight of ingredients is processed before being discharged as finished product. The more modern alternative is a continuous manufacturing process, which simultaneously charges and discharges ingredients and finished products.
Many large corporations have embraced this manufacturing process because they consider it to be an improvement in production. The key benefits of continuous manufacturing processes are the ability to have smaller processing equipment and facilities, simplified processes, and superior product quality control. However, these benefits can only be achieved if the auxiliary equipment is able to keep up. Uninterrupted dust collection is a critical consideration. We will examine these key benefits of continuous manufacturing from a dust collection perspective.
1. Smaller Processing Equipment and Facilities
Smaller processing equipment and facilities should be faster and less expensive to design, build and install. They should also be less expensive because the processes are simpler and more efficient to run and maintain. Compact, fully integrated equipment is required to meet these new demands without compromising on product quality or operational safety.
Smaller facilities can also run with lower inventory levels and lower capital and operating costs. They will also have better “green” credentials, consuming less energy and producing lower emissions. The move to smaller-scale production environments puts the emphasis on machinery and production processes. They will both need to become more flexible and adaptable so they can handle process changes as they occur.
2. Simplified Processes
Each continuous manufacturing process will have extensive planning during the inception stage. This is required to fully evaluate each process step to ensure it is as simple and integrated as possible for optimal product quality and operational efficiency.
Operators can closely monitor the numerous process stages, getting real-time information from machinery to predict potential problems. It’s possible to greatly reduce the occurrence of costly production downtime.
Operators can also reduce manual material handling to protect workers from exposure to potent compounds. A simplified and integrated manufacturing process has shorter processing times. It also maximizes equipment uptime to get products to market faster.
3. Superior Product Quality Control
The FDA implemented current Good Manufacturing Practice (cGMP) regulations to “provide for systems that assure proper design, monitoring, and control of manufacturing processes and facilities.” Continuous manufacturing processes can be designed to follow cGMP guidelines. This provides:
- Greater control over each manufacturing operation
- Reduced product quality issues such as cross-contamination
- Accurate production data for reporting requirements
- Continuous improvement opportunities
Industrial dust collectors have been an integral part of many active production processes including pharmaceutical ingredients (API) and oral solid dose (OSD) processes. Dust collectors extract toxic and combustible dusts from processes including coating, tableting, blending, drying and packaging. They use filter cartridges to remove dust particles from the contaminated process air that pose a serious risk to the health of the workers.
Dust particles in the air can also cause combustible dust explosions and fires, damage products and cause cross-contamination. Dust collection is even more critical in continuous manufacturing operations because they need to run 24/7. The most important requirements are:
Online Filter Cleaning
Dust collectors can run continuously when they clean their own filters using reverse pulse-cleaning. This type of cleaning system uses compressed air as needed to remove dust that is restricting the airflow and raising the dust collector’s differential pressure (dP). Nozzles direct pulses of compressed air into the inside of the filter cartridges to eject the dust from the surface of the media.
The most efficient way to operate a reverse pulse cleaning system is to use a controller that reads the dP across the filters. That way, the cleaning system initiates automatically when the set dP is reached and returns it to a stable level.
The ejected dust is stored in a suitable receptacle where it can be emptied when necessary without having to shut down the dust collector. However, it is possible for the pulse-cleaning process to cause pressure disturbances in the dirty air ducting and the process machine to which it is connected. That’s why it’s important to use proactive strategies to prevent these disturbances such as:
- Reducing the compressed air pressure
- Segmented filter designs
- Off-line cleaning regimes
- Automatic dampers
All of these techniques can be designed into the system to help prevent pressure issues.
In continuous manufacturing, energy efficiency is a key consideration for the design of all ancillary equipment, including the dust collectors. Dust collectors consume energy in two main areas: the fan motor and the pulse-cleaning system. The fan produces the negative pressure to effectively remove the dust that is generated. Well-designed dust collectors that have well-balanced extract ducting minimize the fan’s power consumption. Using variable-frequency drives and high-efficiency motors can also reduce energy consumption.
The second main area of energy consumption is the filter cleaning system. Compressed air is expensive to generate, so the more efficient the filter cleaning process, the lower the dP and compressed air consumption will be. Therefore, it is important to consider the following when selecting the most energy-efficient dust collector for the application:
- The dust release characteristics of the filter media employed
- The design of the filter cartridges
- The design of the cleaning mechanism
As manufacturing processes demand smaller process machines and less floor space, the same stipulations are placed on the ancillary equipment. This includes the dust collectors and the cartridge-style filters that are typically used for dry dust applications. Cartridge-style filters have a greater surface area and smaller footprint than bag filters.
In addition, dust collectors typically need to incorporate a HEPA filter section and a fan, which can take up valuable space in the production floor or suite. Using a fully integrated, compact dust collector is a space-saving strategy that is sometimes a necessity. A more compact unit can also have much lower installation costs.
Every continuous manufacturing process will be evaluated before implementation to determine the potential health and safety risks. With dust collection, the main risks involve:
- Exposing workers to harmful dusts
- A fire or dust explosion from combustible dust
A well-designed and well-maintained dust extraction system will remove the airborne dust from the workplace, reducing worker exposure and preventing cross-contamination of other products. However, workers can also be exposed to the harmful dusts when they remove the collected dust, during filter changes and when doing maintenance work. Containment systems can be used to limit worker exposure and cross-contamination during these procedures.
Dust collector containment systems vary in design, so it is good practice to use a system that has been surrogate tested and validated by an independent organization. It is also important to get a safe-change system that is easy to use so that the maintenance teams don’t have any issues following the instructions.
Fire and explosion risks can be managed effectively if the facility personnel fully understand the process, ingredients or other materials being processed. Dust explosion characteristics are known for many products used in pharmaceutical and chemical manufacturing processes, and this information is required under current NFPA standards. When this information is not available, values such as the Kst (rate of explosion), Pmax (maximum explosion pressure) and MIE (minimum ignition energy) can be determined by contacting a specialist lab to conduct explosion tests. This information is needed to select the most appropriate explosion protection measures, such as explosion venting, and apply them to the dust collector to ensure compliance with the appropriate NFPA standards.
For processes with smaller air volumes, it is sometimes possible to avoid specifying expensive explosion protection equipment by selecting an advanced dust collector that has documented performance-based testing showing that it can safely contain dust explosions. The cost savings can be significant with compact dust collectors, particularly with respect to installation and ongoing maintenance costs.
Reliability is a critical requirement when selecting machinery for continuous pharmaceutical applications. Dust collectors should be tested with actual performance data. In addition, the dust collector supplier must also be able to provide a dedicated sales and after-sales support service to ensure the availability of spare parts so the processes can continue without downtime. Dust collector maintenance must also be as quick and simple as possible to avoid unnecessary production delays. Reliability applies to both the equipment itself and the persons responsible for the project at each stage. A well-established company with a customer-focused approach will be a more reliable partner.
As product manufacturing methods change, dust collectors and other essential process equipment must evolve to meet new demands. Continuous manufacturing processes have numerous benefits and play an important role in current and future production processes used in pharmaceutical manufacturing. Constant developments and improvements in production planning and equipment make it necessary for suppliers to match the demands for performance, safety and reliability.