Cleaning In Place (CIP) process technology enables fast and efficient cleaning of production equipment without dismantling the components. As a result, this technique offers significantly less labor, it reduces production downtime, and it protects employees from direct contact with aggressive cleaning chemicals. CIP is a standard application in many production plants in the beverage and food industries. If required it can be complemented by steam sterilization (Sterilization In Place – SIP).
Conditions for efficient and reproducible CIP-cleaning
In CIP cleaning, all parts of the production equipment, i.e. tanks, pipes and process lines, with all built-in components such as pumps, valves or sensors, are cleared of product residues, traces of cleaning chemicals, microbes, bacteria or other substances by a multistep process with different rinsing and cleaning liquids. A new production process can start immediately after the CIP process.
The quality of CIP cleaning can be monitored by inline analysis or sampling after each intermediate step and at the end of the overall process.
The CIP process costs are influenced by different factors such as:
- Product loss due to inaccurate phase transitions
- Water consumption due to flush cycles that are too long
- Production downtimes during cleaning
- Chemical’s consumption due to inadequate recovery and multiple use
- Wastewater costs due to avoidable quantities of product or chemicals in the sewer
Sanitary sensors can help to increase the degree of automation and thereby
- ensure the reproducible quality of the cleaning result
- supervise product safety (purity of the end products)
- optimize the duration of the individual cleaning steps
- reduce the loss of resources through switchovers in real time
- monitor the multiple use of cleaning agents and water
- control and manage the correct concentration of the cleaning agents
Maximum CIP cleaning efficiency is typically achieved by using the following types of sensors:
- Conductivity meter, e.g. ILM-4
- Turbidimeter, e.g. ITM-51
- Flow meter, e.g. FMQ
- Flow switch, e.g. FTS
- Pressure sensors, e.g. P41
- Temperature sensors, e.g. TSM
- Level sensors, e.g. L3 (hydrostatic) or NSL-F (potentiometric)
The CIP process
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 remaining in the plant is pushed out with water or with pigs and deposits are removed during pre-rinsing. In the further steps, organic trace elements 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 with certainty, 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 end up in the sewage.
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
Analytical sensors in the CIP process
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 cleaner 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.
CIP process control
Each individual step in the CIP-SIP process must be precisely controlled for reproducible and documentable cleaning. The process conditions must be precisely monitored on a continuous basis. The corresponding sanitary sensors for temperature, pressure, and flow as well as flow monitors are available from Anderson-Negele in a wide range for individual installations and for analog and digital communication systems such as IO-Link.
Monitoring of the detergent concentration
For optimum and reproducible cleaning results, each acid and each caustic must be concentrated to the specified value by dosing with concentrate and fresh water. 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 important 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.