Optimising clean-in-place processes in food and beverage operations: Part 2

Existing clean-in-place (CIP) processes are time intensive and waste large amounts of energy, water and chemicals. In Part 1 of this article the risks and costs associated with inefficient CIP processes were discussed, but new innovations in CIP technology can now allow plant operators to cut costs in an environmentally friendly manner while still conforming to regulatory safety standards.

Recent innovations in technology now enable plant operators to calculate the optimal mix of water, chemicals, temperature and flow required to achieve safety standards while saving energy and reducing the downtime for cleaning, as well as providing tracing and documentation.

Optimisation strategy

While every food and beverage processing plant’s requirements are different and details will vary, experience has shown the most successful approach for CIP is based on three pillars:

• Effective and efficient design
• Energy efficiency
• Automation optimisation

An initial audit of each of these elements helps to identify any existing gaps and can establish an execution roadmap for leveraging efficiency and safety gains.

Efficient and effective design

Efficiencies can be gained by introducing smaller, decentralised CIP systems to the plant. This approach reduces the amount of energy required to transport heated chemicals through long pipes to far corners of the production installation. The shorter distances for delivery of detergents, save water, energy and time.¹

Multi-use CIP systems can also generate significant water and chemical savings. For example, a dairy processor in Australia had previously utilised a single-use CIP system. In its old system, all the water and chemicals were used once and then discharged to waste. The system was replaced with a multi-use CIP system that recycles the final rinse water for the pre-rinse cycle. All chemicals used in the system are also returned and circulated through holding vats, where temperature and conductivity are monitored and automatically adjusted to meet specifications. The new CIP system saved the company AU$40,000 per year with a payback period of only one year.²

Improvements such as repairing leaks, removing dead legs (stagnant water in pipes that could grow bacteria), installing self-priming pumps to avoid cavitation issues (bubbles or voids, caused by changes in pressure that can lead to early pump wear) and replacing static spray balls with rotating ones for tank cleaning can lead to significant water savings and improved productivity.

Energy efficiencies

Up to 30% in energy savings can be gained by making improvements to inefficient, outdated equipment components that waste electricity and by modifying wasteful business processes. Examples include introducing variable speed drives rather than fixed speed drives so that operators can specify the flow rate within the recipe parameters. On the process side, adjustments can be made by better balancing rinsing time to rinsing volume.

Energy efficiencies can also be gained from a better managed heating and chemical sorting process (ie, the transition phases from water to chemical, and from chemical to water). Software monitoring will prevent fresh water from infiltrating the chemical tank which then avoids having to reheat the chemical tank.

For example, the fresh water should be maintained at a temperature of 10-15°C and the caustic soda tank temperature should be maintained at around 80°C. If the PLCs that manage the CIP are not set up correctly, fresh water can enter the caustic soda tank, lowering its temperature. In order to return the caustic soda tank to proper operational temperature, some steam (and therefore energy) will be need to be used.

Automation optimisation

Controls, sensors and alarms are all elements of automation that enable dashboards to be implemented and key performance indicators (KPIs) to be set. Typical KPIs may include cubic metres of water per number of CIPs, water re-use percentage, energy consumed per tonne of product or kilograms of wastewater generated per kilolitre of product.³

Automation improves the quality of information available and allows tighter control of the various parts of the cleaning process (such as creating parameters around the opening and closing of valves and pump operation). It is important that the automation architecture is open; this enables the CIP processing equipment to communicate with other process equipment such as tanks or pasteurisers. Integrated ‘status check’ ability streamlines the efficiency of the operation.

An efficient cleaning recipe is based on four key parameters (sometimes referred to as the ‘4T rule’). The process automation system monitors and verifies these four fundamental parameters. By using software to calculate the optimal combination of each parameter, a dramatic reduction in costs can be achieved. The four ‘Ts’ are defined as follows:

• Time - Duration of the cleaning cycles
• Temperature - The temperature of the cleaning products
• Titre - The concentration of the cleaning products
• Turbulence - The speed and impact of liquids projected by cleaning products that need to be generated to perform the cleaning task (1.5 m/s minimum speed)

A good analogy for understanding how the 4T rule works is to compare the process to a human washing greasy hands. Grease on skin needs a particular amount of soap or detergent to remove the grease (titre). In addition, the water needs to be hot enough to react with the grease and detergent (temperature). The hands need to be rubbed together (turbulence) for long enough (time) to be completely clean. If any one of these elements is not quite right, eg, not enough soap, the water is cold or the hands are not washed for long enough, then the hands won’t get clean.

In addition to cleaning recipes, system optimisation also hinges on the design and interconnectivity of the pipework, valves, pumps, instrumentation and PLCs. This infrastructure enables the software to communicate within the system. An expert with knowledge of process and instrumentation drawings (PIDs), automation software, as well as food and beverage industry cleaning applications, can simplify the planning, design and operational deployment process.

A PLC/SCADA application with dedicated library for CIP enables an operator to have full visibility over the automation system, and to deploy the correct recipes (implementing the 4T principles) at the right time.

Historical data generated by such a system can help to further optimise the operational parameters. The CIP optimisation software can be configured with different cleaning recipes which can be implemented at the push of a button, making plant operation more flexible. Different recipe settings and cleaning parameters can be aligned with specific pieces of equipment.

The automation software also enables simplified root cause analysis of any issues. The information stored in the library can also be utilised to generate ‘proof of clean’ reports as requested by food safety authorities.

System performance efficiency can also be tracked and compared to an established benchmark. If any anomalies are observed, the software can drill down into specific elements or sub-processes of the system to help troubleshoot any issues.

For example, an incident was observed recently in an Australian dairy factory. A valve opened to indicate that the cleaning cycle was in progress. To the operators, the system appeared to be functioning properly. The CIP optimisation software discovered later that a pump was not working (therefore, no cleaning fluid had passed through the pipes). The repercussions of not being aware of this problem could have been very serious. However, the problem was averted as the faulty pump was picked up by the automation system report, and the incident was examined in the library to identify the root cause of the problem. Without such a reporting process it is possible that system operators may have realised that a problem existed and re-run the CIP process just to make sure it was clean. However, in this particular instance a re-run would not have helped.

Within such a system, it is possible to define which sequence has the best profile according to the 4T rule (this is called a ‘golden CIP ratio’) and then compare this optimal ratio to the actual performance each time a cleaning program is run. If the chemical tanks are displaying an incorrect temperature or an incorrect percentage of chemical (titre), or if the duration (time) is not the same, or if the flow (turbulence) is not the same, the tool will decrease or increase the golden CIP ratio according to the difference. The golden CIP is benchmarked at 100. If the number shows 50 it means that there was a significant problem during the caustic soda or acid phase or both. Within the software windows it is possible to check the detail as to which parameter was not performing according to the weight that has been predefined for each key ‘T’ parameter.

It is also possible to track and manage all chemical waste that goes down the drain. If the conductivity meter indicates that it is in a chemical phase and the drain valve is still open, the software tool has a counter showing the volume going down the drain. To manage this volume it is possible to configure a threshold by colour-coding the counter (such as red or yellow) when it reaches this threshold.

A final check can be made following the last rinse. The software will indicate a ‘remaining conductivity’ measurement. If this number is high then it means that the final rinse was not well done and that some chemicals are still present in the pipework.

Operational savings

An example from a Schneider Electric customer illustrates operational savings gained from an optimised CIP system (see Figure 1)⁴. In this instance the costs of water, caustic soda and acid were calculated for three months before CIP redesign and for three months afterwards. While the water usage increased slightly as a result of the optimisation, this was more than balanced out by the dramatic reduction in chemical needs.

Figure 1: Monthly costs before and after CIP optimisation.

An annual savings of approximately €90,000 was realised without taking into account the increase in production uptime or reduction in energy consumption.

Cleaning the cleaning system

Periodically, the cleaning system itself needs to be cleaned. It is important to include this aspect in the CIP design as it requires dedicated pipe and spray balls to be fitted in the CIP tanks. CIP automation software should feature an automatic cleaning recipe that can be activated by the operator at regular intervals. This auto cleaning will remove build-up of cleaning products and residue in the pipework and tanks, therefore enabling the CIP system to operate at maximum efficiency.

Conclusion

Food and beverage manufacturers that seek to increase operational efficiency and cut costs should begin by performing an audit of their CIP system to identify areas for improvement. The audit will help determine whether incremental improvements such as balancing out the line capacity or adding a recovery tank to re-use water need to be made.

A high level of efficiency can be achieved by addressing CIP design, energy-efficiency improvements and advanced process automation. Such an initiative will result in a positive impact on waste, energy cost, and environmental resource issues. Improved food safety and increased production will benefit both peace of mind and profit margins.

*About the authors

Benjamin Jude is a Global Solution Architect/Food & Beverage Vertical Expert at Schneider Electric. For over 20 years he has specialised in automation and process engineering, and has provided turnkey solutions for firms within the food and beverage and pharmaceutical industries. He has particular expertise in process design and electrical control engineering, batch management (MES) and FDA compliance.

Eric Lemaire is Food & Beverage Group Marketing Director with Schneider Electric. He holds a degree in Food and Beverage Process Engineering and has more than 20 years’ experience in the process automation industry. He has held many different engineering, R&D, marketing and sales positions, including manager of the French Food and Beverage and Pharmaceutical Industry operations.

References

1. Source: Bulletin of the International Dairy Federation 401/2005.
2. Source: Eco efficiency for the dairy processing industry.
3. Excerpt from Typical key performance indicators for a dairy processor: Eco Efficiency in the Dairy Processing Industry.
4. Data for this graph was taken directly from a report provided by a Schneider Electric customer in France.