In our last blog we talked about the design and installation of a “state of the art” Automatic Cream Yeast System. In the article we made passing reference to cleaning the system but we felt that cleaning is such an important aspect of system installation that it deserved an article of its own.
That a design is only as good as its weakest link may be a cliché but it is one which designers ignore at their peril. And when designing something as specialised as a cream yeast system, if particular attention is not paid to cleanliness then disaster will follow. That is why we consider that cleaning processes should be designed into the system at the start and be looked upon as one of the major aspects of the system rather than as an afterthought.
For the installation in question, Beswick Refrigeration integrated a Clean In Place (CIP) system. Looking at the triple drivers of efficient cleans, minimising production down time and environmental consideration, the system which we designed and built was based on the following CIP design philosophy:
1, Product recovery -purging product from Ring main lines back into the bulk storage vessel for recovery
2, Pre rinse- this is carried out with recovered water and is intended to remove the vast majority of product residue from the system. The more effective the pre-rinse the less work is left for the detergent to to-do and consequently the detergent’s useful life is dependent upon this. The flow rate is set as high as is practical and the length of the rinse was determined during commissioning of the plant based on worst possible case scenario.
3, Detergent circulation – this section of the process is intended to remove any traces of the product that could not be removed by rinsing alone. The cleaning consists of a number of operations that are all happening simultaneously.
– Kinetic cleaning: “scrubbing action” produced in vessels by the impingement forces as a jet of liquid impacts on a solid surface or by the turbulence generated in pipe work cleaning, this cleaning produces the largest of the cleaning forces.
– Chemical reactions: Both acid and alkali detergent work by reacting chemically with the product to be removed and in general these reactions convert something that is immiscible with water and turns it into a product that easily dissolves in water (oils are converted by alkalis to soaps, proteins are converted by acids to salts)
These operations all take time to work and the detergent circulation time is established during commissioning.
4, Post detergent rinse -this rinse purges the detergent to drain or back to the CIP system for recovery, the rinse water is used to” top up” the level in the CIP detergent tank, Replacing liquid lost during the detergent circulation (valve seat flushes and dosing points)
5, The Sanitizer cycle is required to ensure the bacteriological quality of the plant being cleaned. Peracetic acid based sanitizers are highly bactericidal and produce excellent sanitation from all microbial and many virus contaminants, care is taken that they are not contaminated by traces of alkali detergent or recovered rinse water with detergent traces in it, this is especially true for peracetic acid based sanitizers that are rapidly rendered ineffective by alkali solutions.
6, Post sanitizer rinse – this final rinse water is recovered back into the CIP system.
7, Final drain down – This stage opens all drain valves and allows any remaining rinse water to drain from the plant prior to food production.
8, At the end of the drain down operation the plant is clean and ready for production! The CIP system indicates this to the operational staff dealing with the production process .
9, Evidence of cleaning needs to be collected and recorded, although this can be achieved with operator completed log sheets. Most companies prefer to opt for a data-logging system linked either to a main process control system or to the CIP control system. Beswick Refrigeration Services complimented its new fully automatic Cream yeast system with a 10” HMI (Human Machine Interface) providing the following details for all CIP’s carried out
– What was being cleaned (Tank or Ringmain)
– When the cleaning operation took place
– The temperature and concentration of the detergent
– The time that the detergent circulated at the correct temperature/concentration
– The temperature and concentration of the sanitizer
– The time that the sanitizer circulated at the correct temperature
– Flow rates during the cleaning cycles