Clean-In-Place (CIP) optimization with sensor technology

A CIP cleaning process consists of several coordinated steps. In general, these are

• Push-out (water or pig)
• Pre-rinse (water)
• Cleaning (caustic)
• Intermediate rinse (water)
• Cleaning (acid)
• Final rinse (fresh water)
• Steam sterilization (only for CIP/SIP cleaning)

First, the product in the plant is pushed out with water or projectiles (pigging) and deposits are removed during pre-rinsing. In the further steps, organic residues are eliminated by means of caustic, and mineral deposits are removed by the use of acid. Intermediate and final steps are flushing with water.

The duration, intensity and temperature of the individual cleaning steps depend on many factors, such as the chemical properties and viscosity of the products, whether only one or several alternating products are run in a system, the technical properties of the system (e.g. tank size, tube diameter, pipe length, etc.) and production-specific devices in the process (e.g. heater, filter, spray nozzles, etc.).

Often, the process is controlled through predetermined, pre-calculated process parameters. The pressure and thus the flow rate, the temperature and the duration of each process step and the corresponding control of the valves and pumps are programmed into the PLC and then run automatically. Such a passive control for the CIP process must take into account the above factors individually. To avoid defective results and to achieve the required cleaning quality, time buffers and safety margins must be provided between each individual step. This extends the overall duration and also leads to resource losses due to changeovers that are too early or too late, i.e., too much product or chemicals can go down the drain.

Analytical sensors such as turbidity or conductivity meters, your "eye in the pipe", measure the quality of the liquids inline and continuously, thus enabling active control in real time, based to the momentary circumstances.

You can precisely control at any moment

• which product is in the line
• which concentration the product has (pure product / mixed phase / impurities)
• the contamination level of the liquid

This allows for

• a control of the end products purity, since a deviation from the specification is immediately reported to the PLC. This prevents, for example, traces of detergants or water from entering products.
• a real time phase transition, as the sensor response time is in the range of a second and the valves can be controlled without time loss.
• a precise routing of all resources such as product, detergent and water, with the least possible loss.
• multiple use of rinsing water and cleaning chemicals, as these can be temporarily stored in special tanks for pre-rinsing or pre-cleaning if the degree of contamination / turbidity is below a specified value. Significant savings in agents, costs and wastewater pollution are also possible here.
• a minimization of the duration of the cleaning process, since the next process step can always be initiated with second precision when a setpoint is reached.

Each step in the CIP-SIP process must be precisely controlled for reproducible and documentable cleaning. The process conditions must be rigorously monitored continuously. The corresponding sanitary sensors for temperature and pressure, flow meters and flow switches are available from Anderson-Negele in a wide range for individual installations and analog and digital communication systems such as IO-Link.

For optimum and reproducible cleaning results, each acid and each caustic must be concentrated to the specified value by dosing with concentrate and freshwater. Depending on the application, this is approx. 0.5 to 1.5 % for caustic solutions and 0.5 to 1.0 % for nitric acid solutions and can be precisely monitored via conductivity measurement. In this case, high measuring accuracy and resolution with simultaneous efficient temperature compensation play the most critical role for the sensor since the specified value of the concentration must be maintained extremely precisely for a verifiable cleaning result. This is ensured by the high accuracy conductivity measurement with the ILM-4 in a separate process line.

Milk truck cleaning: Complete sensor system for efficient certified and approved CIP cleaning
Reduce CIP Costs and Improve Overall Efficiency with LowCost, Easily Installed Turbidity Sensors
Cost of Delay – ROI Model

• Conductivity meter, e.g. ILM-4
• Turbidimeter, e.g. ITM-51
• Flow meter, e.g. IZMAG
• Flow switch, e.g. FTS
• Pressure sensors, e.g. P42
• Temperature sensors, e.g. TSM
• Level sensors, e.g. L3 (hydrostatic) or NSL-F (potentiometric)