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Best Practices of Automated CIP Systems
Using automation to create safe, reliable, and robust CIP systems for today’s demanding food production cycles
by Stephen Malyszko, PE
Clean-in-place (CIP) systems are used by food manufacturers to eliminate the soil load buildup during normal production. CIP systems vary widely in configuration, operation, and the level of automation. In many companies, plant, corporate engineering, IT, and their partner integrators are pitching in to create robust automated systems to improve CIP operations by reducing cycle times as well as reducing water and chemical usage. The techies are helping production in many ways by using the most current technologies for computers, process controls, instrumentation, software, networking, and security in CIP. These platforms are being integrated into comprehensive systems to provide new levels of efficient and effective CIP operations, data capture, and real-time information analysis. Let’s explore the tools making automation in CIP contribute more to the bottom line than ever before.
CIP Systems: Different But All the Same in the Eyes of Automation
Configurations vary for CIP systems. They typically include self-contained skids; kitchens with large tanks for single CIP systems; and kitchens with large alkaline, acid, sanitizer, and recovery tanks for simultaneously servicing multiple CIP systems.
Whether a CIP system is a skid or kitchen, it can consist of the following.
- One Tank – combined rinse and wash
- Two Tank – separate rinse and wash tanks
- Three Tank – rinse, wash, recovery
- Four Tank – any combination of rinse, wash, alkaline, acid, sanitizer, recovery
- In-line or in-tank chemical dosing for one-pass chemical usage systems
- Separate chemical tanks for alkaline, acid, and sanitizer for multi-pass chemical usage
Components common to the variety of CIP systems include water supply source; supply pump; supply-side heat exchanger and temperature transmitter; tank inlet, outlet, and recirculation valves; chemical addition pumps; and chart recorder, either paper-based or electronic, to record, at a minimum, temperature over time.
CIP operations can be successfully run with this configuration, although a high degree of manual control, constant monitoring, and intervention is necessary to insure effective and safe operation. Production usually finds it very difficult to maintain consistency of chemical concentrations, wash temperatures and times, and rinse water quantities. Worse yet production may routinely over compensate the operation by adding more chemicals to insure minimum cleaning requirements are met or running at higher temperatures, longer wash times, and greater rinse water quantities; all more costly to operations.
Better Instrumentation and Controls
Manufacturing can significantly increase efficiency and reduce operating costs for CIP by enhancing systems with additional components. More robust CIP systems will have the following components.
Supply side flow transmitter – rinse and wash steps can be precisely controlled by totalizing the liquid quantities delivered to each CIP circuit.
Variable frequency drive on the supply pump – supply side flow rates can be precisely controlled with a loop control tied to the flow transmitter above. The benefits gained are ensuring line circuits achieve minimum liquid flow velocities for surface contact in the various pipe diameters, and sufficient flow through spray balls for tank circuits.
Supply side line pressure transmitter – monitor point to detect if an obstruction in the circuit is present when pressure is too high or a break in the circuit exists when pressure is too low.
Level transmitters or level probes on the tanks – used to signify when action needs to be taken; especially when low levels are reached before or during a CIP operation.
- Fresh water tanks – refill to a mid or high level
- Chemical tanks – add more water and the appropriate chemical to have
- sufficient solution for the appropriate wash step(s)
- On high level – stop filling the tank
pH transmitters for alkaline and acid tank makeup – monitor point used when combining water with the alkaline and acid chemicals to the desired concentrations and pH levels.
Proximity sensors – for all possible connections made at manual hook-up stations or “swing panels,” monitor points; used when initiating a cleaning circuit to verify all connections are properly in place for the specific circuit; used during the cleaning sequence as a safety monitor in the event a hook-up connection comes loose potentially spraying hot water and/or dangerous chemical solutions in an area.
Return side temperature transmitter – monitor point to insure the entire circuit is being cleaned at the required minimum temperature.
Return side liquid flow switch – monitor point to detect liquid is returning to the skid or kitchen from the circuit being cleaned. Typically used in conjunction with a timer creating a notification to the operator to stop the system and check for leaks or to check for incorrect circuit hook-up points.
Return side conductivity transmitters – monitor points to detect the absence or presence of chemicals. Rinse step times can be shortened when chemicals are not detected in the liquid returning to the skid or kitchen. Conversely, wash steps can be initiated sooner when chemicals are detected at the required concentration level in the return solution. In some applications a second, more sensitive, conductivity transmitter is used to sense the complete absence of chemicals in the final rinse step.
Return side turbidity meter – monitor point to detect the amount of solids in the return liquid stream; used to prevent liquids with high solids content from being directed into a recovery tank.
Process controller, such as a PLC or DCS – used to control the CIP steps together with checking for limits and alarms. This topic is covered in more detail below.
Human-machine interface (HMI) – the operator’s window into the system for control and monitoring the CIP process while operating. Again, this topic is covered in more detail below.
Performance-Packed CIP Controllers and HMI Platforms
CIP Control Platforms. A variety of PLCs and DCS platforms are well suited for controlling the range of simple to robust CIP systems. Simple CIP systems many times have a small stand-alone PLC or DCS controller. More operational complexity and additional instrumentation in the CIP system generally sets the need for more powerful controllers. Both PLC and DCS control platforms offer features attractive to users from different perspectives and preferences. The more common attributes of both platforms are ability to handle a variety of field devices found in today’s manufacturing environment; ability to interface to multiple device communication networks such as EtherNet/IP, ControlNet, DeviceNet, Profibus, AS-i Bus, Foundation FieldBus; ability to create structured code along with intuitive labels and tags within the programming; and closer integration with the HMI’s and data historians, event archivers, and relational databases (covered below).
Process controllers no longer live on the plant floor as separate “islands of automation.” Rather process controllers closely work together. Controllers are tightly integrated for both process and CIP. For high-availability and high-criticality applications, several process controller manufacturers offer redundant “hot-backup” configurations addressing the concerns over “single-point” hardware failure.
HMI. The user interface between the operator and the CIP process, commonly referred to as the HMI continues to be the most dominant window into the CIP process. The typical traditional HMI hardware platform was a stand-alone proprietary device or a Windows-based computer tied to either a proprietary bus or an Ethernet network. The preference in hardware platforms for HMIs is rapidly changing in food manufacturing. Thin clients and terminal servers are being used in both new applications and upgrades to legacy process control systems for CIP.
Thin clients are, generally, diskless processors that interface over an Ethernet network to a server where terminal server HMI software and application files reside. Thin client hardware requires minimal configuration compared to thick clients (traditional Windows-based computers or proprietary stand-alone HMIs). Different process and CIP screens can be simultaneously viewed by operators at different HMI workstations (thin clients).
Plant operations have seen savings using terminal services and thin client technologies. Food manufacturers have seen 33 percent savings in PC costs for operator workstations; 55 percent reduction in power consumption by the operator workstations; and reduction from four hours to less than 30 minutes for a technician to replace an operator workstation.
Combining the Two for More Bang. These robust controller and HMI technologies, combined with the additional instrumentation can provide production with more efficient CIP operations. Consider the following time and money-saving enhancements.
Recipe-based CIP circuits – make CIP circuit parameters part of a selectable recipe through the HMI. The parameters can include rinse and wash times/quantities, drain times, flow rate and temperature set points per step, line pressure limits per step, conductivity and turbidity limits per step, quantities of chemical additions, and alarm limits for all operating parameters.
Systems can be configured to allow these CIP circuit recipes to be created and edited by an authorized person without the intervention of a programmer. All parameters are viewable and accessible from menu screens on the HMI. Each CIP circuit recipe is then stored in the controller.
Real-time monitoring of the entire CIP process – the operator sees an intuitive view of the progress and condition of the cleaning process. Information on the HMI includes which CIP circuit is being run, current step being run, condition to complete the step, next step to run, elapsed step time, time remaining in the step, target and current flow rate, supply pump speed reference, target and actual supply and return temperatures, conductivities, pressures, pHs, tank levels, valve positions, liquid flow path, system notifications, warnings, and alarms. The operator is constantly shown when the CIP system is operating as intended and is immediately notified when wash and rinse parameters are outside allowable limits or an abnormal operating situation occurs.
Real-time trending – the operator can view at the HMI the performance of flow rate, temperatures, pressures, conductivities, pHs, and turbidity during the CIP process.
Historians for Data and Events
CIP Process Data. Traditional methods for recording process parameters, such as CIP temperatures, to meet regulatory compliance relied on paper-based circular or strip chart recorders. Maintenance of these electro-mechanical devices was always a top priority to insure their reliability, accuracy, and repeatability. Each chart recorder had multiple points of mechanical failure including the ink dispenser, ink supply, and pen driver mechanisms.
Today, food manufacturers are eliminating chart recorders and replacing them with historians; software-based data recorders extracting CIP process parameter values on a continuous basis from the PLC or DCS controllers. Today’s data historians can simultaneously and continuously record tens of thousands of individual process parameter points per second. Most data historians use data compression algorithms to optimize the use of mass storage either on a local computer or in the cloud.
Trends of the CIP parameters, such as temperatures and flows, can be displayed on the HMI as well as printed out for inclusion with paper CIP records. The raw data is electronically stored and available for review and analysis days, weeks, months, or years later.
CIP Event Archiving. Traditional methods for recording events, such as circuit start time and end time or target and actual wash times and quantities, have been paper records created by the operator. These manual records do meet regulatory compliance and are very labor intensive. Their accuracy and completeness rely entirely on the operator. Maintaining paper records becomes critical for traceability of the cleaning process.
Like the historians described above, food manufacturers are moving away from the paper-based CIP records and embracing software-based event archivers and report generators. Similar to the historians, the event archivers, or transaction managers, record events germane to the CIP process. Typical recorded events include CIP circuit start and completion times, wash times and quantities, operator interventions such as putting the system in “hold” or advancing a step, repeating a step, or aborting the circuit. The significant advantage to using software-based transaction managers in lieu of paper records is the critical event data is automatically captured via the process controllers and HMIs then stored in a relational database such as Microsoft’s SQL Server. Once the event data is captured, CIP and other reports can be generated.
The event archiver and reports can also be created to be compliant with regulatory requirements for electronic records. Executing this step provides the food manufacturer the ability to eliminate paper records for CIP.
Food manufacturers can improve their CIP operations and efficiencies by effectively utilizing current technologies for CIP process automation. These technologies have already been used in applications. Critical to reaping the benefits of using these newer platforms is to have the system designers, production, maintenance, and quality work closely together from a project’s inception to completion so all system requirements, specifications, documentation, and regulatory requirements are cohesive and uniform. Success is achievable for those willing to take advantage of the proven technology platforms available today.
Malyszko is the co-founder, president, and CEO at Malisko Engineering, Inc., which delivers validated automation solutions for process manufacturing facilities focusing on food and beverage, pharmaceutical, life sciences, dairy, and specialty chemical applications. Malisko is a certified member of the Control System Integrators Association, www.controlsys.org, a non-profit professional association that seeks to advance the industry of control system integration. Malyszko can be reached at email@example.com.