I am now starting the topics on tougher issue of process engineering i.e. Filtration. It’s not in a sequence as I am not in a position to find my papers one by one during this turmoil. So this one is related to selection criteria of CIP filters. How to choose them and what are the factors affecting selection.
The concept of CIP dates back to 1950 when it was first developed & applied in Dairy Industry.
The conventional definition of CIP (Cleaning In Place) as name suggest is the removal of process contamination and cleaning of process system by re-circulation or spray application of flush, wash & rinse solution without removal or dismantling of process equipment’s.
Now first let us understand the factors important for CIP filters.
1. Clarity of Filtrate
This decides the no of stage required in a filtration system. The higher the no of stage of filtration, higher will be the filtrate clarity. More the no of stages, it is difficult to handle the filtration process / system in terms of maintenance etc. Hence, it’s better to use CIP filters to reduce various cost components as given below.
2. Cost of Operation
What are the factors contributing towards cost of filtration? Other than indirect cost factors some direct cost components are more important to work out for the overall cost of filtration. These factors are
a. Cost of Filter Element
In general, the costs of operation are generally lesser in case of cleanable filter elements as compared to single use type or use & throw type. This is simply because of higher material processing output in the same cost. The disadvantage of using a single use type element is mainly the disposal cost and safety aspects.
b. Cost of filtration aid (if applicable)
Lot of lab work is required to find out suitable aid before going into commercial operation. Then optimization of its quantity is required and then cost optimization is required.
c. Energy Cost
The cost of energy to operate the feed system, pumps, filter itself, cleaning system etc. etc. is to be calculated. The point is that it is not only main filtration system but all the paraphernalia is to be included in energy cost.
d. Cleaning System The cost of cleaning the entire filtration system includes, the downtime cost, the consumption of cleaning media, the power consumption during cleaning and re-assembly. The re-charging of the entire system, the losses, the time consumed in making pre-filtration bed etc. is a cost of operation of selected filters.
Generally, during main operation cost of manpower is less as today we have many automatic systems in all types of filtration's but the major manpower cost comes during cleaning where time is an important factor and hence excess manpower is required. Generally this manpower is than adjusted in some other jobs as compromise.
f. Loss of Product
Every time the filter is stopped for any activity like cleaning etc. there is some spillage loss, some loss due to dead volumes in the vessels filter etc., some losses in the form of liquid content of solids, pipeline drainage etc. All these factors contribute to a significant yield loss of product in general. Here the concept of CIP is very useful in such scenarios.
3. Filter Size
In general, if frequent cleaning requirements are there batch cycle time (unproductive) goes high and to compensate for that process engineer will select larger size of filter. This increases space requirement, cost of structure to hold it, higher capital cost. This also means high downtime and high production loss in case of failures. So again CIP is better.
Safety of operator is most important part of any chemical process so is the case with filtration as well especially when material is hazardous or toxic in nature. The importance of a closed system is of utmost priority due to such nature of process fluid. The minimum operation in manual mode e.g. opening and cleaning of filtration system is never permitted and CIP is the best solution in such cases.
This is another neglected aspect which is now in focus in all chemical industries. Whether it is CIP or no CIP it has to use lesser amount of cleaning fluid to generate less effluent. This is also the reason of avoiding use & throws filters as they pose serious threat to environment if disposal is not safe & not regulated. In EU countries, due to strict norms of disposal, the cost of disposal of used filter element is higher than new one and that is right in a sense that if we do not care for our environment one day it will be full of waste. So we have to regulate it.
Above issues and factors are to be considered during a new selection of filter type and are more prominent if we are planning for replacement study. In general, if safety & environment is the major concern OR material is toxic or hazardous it is simple to decide to go for CIP filters. Once decided, plan for the replacement of old filters quickly. For the economic evaluation / justification criteria for the management shall be given in my next post CIP – Filter Selection Criteria – 2.