agosto 17, 2023 posted in Food and Beverage Plants
Compliance with all required local codes for plumbing and mechanical systems is minimal, but further compliance with USDA and FDA requirements may also be necessary. These and applicable Good Manufacturing Practices (GMPs) are incorporated as required for each project.
GMPs ensure both product safety and product quality and should be closely followed as required by each food sector and regulatory practices.
Processing areas must be able to be thoroughly cleaned and sanitized. The building should be designed to eliminate cracks, crevices, and any surfaces that cannot be properly washed down and/or otherwise sanitized. For example, don’t use “open” piping runs that can collect dirt and debris within the processing area. A more desirable configuration would be to use pipe rack structures for distributing utility piping services within the interstitial space with vertical drops to individual pieces of equipment. Services can be nested in a compact piping array that typically includes electrical distribution, steam, water, and compressed air as long as the array is inspectable and cleanable. Distribution runs then extend from the central tray to the various pieces of equipment requiring services.
The best way to handle the volume of water that many processing and clean-up activities require is through proper drainage. Pitching the floor at an adequate angle ensures quick and adequate drainage if you have provided enough floor drains to remove the waste. USDA requirements are generally one drain per maximum of 400 square feet at a minimum of 1/8” per foot slope. ¼” is preferred given that the installation of a 1/8” slope is very precise, and many installers cannot execute without water ponding in some areas. Water can be collected in spot floor drains or in trenches in accordance with the plant’s preferences. Cleanouts and screened pits must be located outside the processing areas – perhaps in adjacent hallways.
Process waste should always be separated from sanitary sewage systems, and any necessary connections between the two must occur outside the building and equipped with air brakes or backflow valves. Similarly, raw process drains and Ready-to-Eat (RTE) process drains should be kept separate until outside the building in a pit or grease trap. This will prevent potentially dangerous backflow of human waste into the manufacturing facility or raw process waste into the RTE waste floor drains. Some process waste may require pretreatment to address BOD, TSS, etc., before discharging to the municipality.
Some refrigerated storage areas can require floor drains due to melting water from iced products or for the cleanup of liquid product spills. Drainage should also be provided in refrigerated areas for any condensation from refrigeration evaporators. Condensation should generally be run to a hub drain and not allowed onto the floor.
All drainage systems need reliable materials, such as corrosion-resistant piping. Remember, the materials you choose must be in accordance with USDA or FDA guidelines and all applicable local code requirements.
Demands for drainage following clean-up and other water-use processes vary with the process. One system may require hot water; another may not. Where systems require larger amounts of hot water, high-volume “instantaneous” steam-to-water systems or direct-contact water heaters should be considered. Other options can include storage tanks with smaller-sized heat exchangers.
High-pressure water for area and equipment cleanup uses less water and time than lower-pressure water. It is typical to provide booster pumps and on-demand water heating to satisfy this need. Modern natural gas-fired submerged combustion hot water heaters offer instantaneous supply at 99+% efficiency and should be considered where flows for sanitation are high. The water pressure should be evaluated in each application to ensure that the pressurized water does not atomize bacteria and contaminates the air and, thereby, onto the food products or food contact work surfaces.
All processing plants need an adequate supply of clean, potable, quality water. Water may need to be treated through various processes such as de-ionization, chlorination, reverse osmosis, etc., depending upon the needs of the plant and the quality of the water supply available.
Although water supply systems will often use copper tubing, the pressure requirements of individual systems or individual pieces of equipment may be such that other materials may need to be also considered. Copper pipe should transition to stainless steel within the processing rooms. Pipe insulation must be chosen to be compatible with the service while avoiding food safety risks. Fiberglass and mineral wool pipe insulation are inappropriate in exposed food handling areas.
When the high cost of fuel is considered, along with the inherent inefficiency of boilers and heat exchangers, it is often prudent to avoid using steam for heating if possible and to use steam only where nothing else will do.
Several types of steam may be needed in a food processing plant.
Centralized boiler rooms typically generate high-pressure steam, and the type of boiler needed to generate the steam will vary with the size of the system. Larger systems may use packaged fire tubes or water tube boilers, whereas smaller systems may use cast iron boilers. Condensate should be returned to the boiler system for reuse, reducing the amount of chemicals needed to support the system. Because this reuse will also reduce the freshwater makeup of the system, it will also reduce the number of suspended solids. A gravity condensate return system is ideal but often not practical. When it is impossible to use gravity to drain condensate back to the central boiler room, condensate return pump sets should be located throughout the plant to pump the condensate back. Because of its corrosive nature, however, piping to carry steam condensate must be carefully selected and specified.
Low-pressure steam can be provided by pressure reduction of high-pressure steam at the point of use. If high-pressure steam is not available, it is recommended to use a steam generator such as one made by Clayton.
Culinary steam is made in a small stainless-steel boiler using no treatment chemicals and provided with a sanitary steam filter at the point of use.
At some point in the facility planning process, the floor plan is fixed. Designers have decided on the types and materials of construction, the type of process systems, and the configuration of major supporting systems. To arrive at a total system concept that best suits operational needs, at this juncture, the various electrical, communications, and security systems should be evaluated. Electrical loads will typically consist of all or most of the following:
The total load for each system should be tabulated and multiplied by some appropriate diversity factor to allow for a realistic value for the facility’s demand kilovolt amps (KVA). The value, with a factor for future growth added, will allow for sizing of the power transformer, secondary service, and main distribution service. These factors and loads should be arrived at from discussions with plant personnel regarding the anticipated operating procedures of the plant, such as the number of shifts and the number of days that the plant will be operated per week. Electrical service, distribution, and spaces for required equipment can then be allocated, allowing for a smoother design process.
The primary consideration in any electrical service will be the source of power. Depending upon the utility, the power requirements of the facility, and the electric rate schedule, either primary service or secondary service will be needed for “service entrance” to the facility. In one case, the utility has its metering at the facility property line, and the customer owns the step-down transformer and all equipment inside the property line. In a more common situation, the utility owns the step-down transformer and has its metering on the secondary or low-voltage side of the transformer.
A main distribution switchboard routes power throughout the facility, feeding motor control centers (MCCs), and distribution panels. For required loads such as uninterrupted power supplies and microprocessors that need a high degree of power quality, individual “isolation transformers” may be appropriate.
Whether a control is a simple on/off switch or a computer-based system, it must be correctly matched to the process at hand or risk losing efficiency and economy. Control Systems Design must also balance the requirements of management and the requirements of the process in order to provide the best system possible. Although occasionally at odds—especially where costs are concerned—skilled systems control designers should be able to overcome these obstacles.
While controls are involved in every aspect of a project, they can generally be grouped into three main areas: manufacturing, HVAC, and refrigeration processes. These areas may be tied together but are usually configured as separate systems.
If carefully analyzed, planned, and implemented, control system equipment will provide many years of reliable operation. It should also provide the opportunity for adequate expansion, maximizing the return on the owner’s investment in design, development, installation, and start-up.
Several factors can impact control system design and selection:
The major questions for any control system designer are, “What needs to be controlled?” and “What are the restrictions placed on the control system design?”
Should the project involve a new facility, there is essentially a “clean slate” on control system architecture. Owners will usually want to install the most up-to-date cost-effective system for the new manufacturing process. Levels of automation can range from separate stand-alone pieces of machinery to totally automated systems that are controlled by a shop floor computer under the supervision of a “central” computer system. Often stand-alone pieces of equipment will need to be integrated into the overall control system. Should the project involve refrigeration, the compressor manufacturer will generally design the equipment-related controls as part of the overall control system.
If the project involves expanding an existing facility, complex control system design issues may need to be addressed. The type of controls in the existing facility, whether the project involves expanding the existing process or installing an entirely new one, must be reviewed. In the case of an existing system, the designer must understand current system capacities and the availability and capacity of existing utilities servicing the system.
Whether designing a new system or expanding a current one, designers must adhere to the existing control philosophy of the owner. Many companies will settle on a particular manufacturer or type of equipment as their standard for all control systems. Conversely, the owner’s preference may be only that they prefer relay logic, programmable logic controllers (PLCs), personal computer, tablet, or phone control systems as the standard. Within that philosophy, any piece of hardware or software which meets the criteria will likely be acceptable.
Many companies, however, will have settled on both a particular hardware platform and a software platform as their control system of choice. Although this decision may be restrictive, it makes the system designer’s task easier in that they can simply go to a single hardware/software supplier to specify components of the equipment for a particular project if the specified platform performs the functions necessary.
Regardless of which control system is chosen, the people running the plant must be able to use it. In today’s food processing industry and at the plant level, maintenance staff may range from several individuals trained on the latest technological advances and troubleshooting techniques to no one in-house able to address these areas— with any necessary maintenance contracted out on an as-needed basis.
The maintenance staff’s training level will obviously affect the control system equipment selection. If there is a well-trained maintenance staff, they should have well-established working relationships with local hardware/ software support to obtain spare parts, technical assistance, and training upgrades as necessary. If this is the case, the systems designer can specify and install equipment without significant worry that it will be properly maintained.
If the maintenance staff is poorly trained or non-existent, the control system designer’s job becomes more difficult. They must identify suppliers with local technical expertise and service help readily available should the installed equipment need repair. If a local source of service and repair is unavailable, redundancy needs to be built into the system to avoid costly production downtime. The system designer should therefore try to specify reliable, off-the-shelf equipment to minimize the need for service and repair.
In today’s 24/7 business environment, many food-processing facilities operate around the clock. With existing production lines, the unavailability of downtime can severely affect any decision to install a new electrical service when upgrading or expanding a system. In most cases, it will be advantageous to simulate the new system prior to installing it in the owner’s facility, which will provide for the most expeditious and trouble-free start-up possible.
Learn about Austin’s food and beverage plant design and construction capabilities, and join us next month as we explore the role water plays in manufacturing plant design.