Disadvantages of fouling(fouling costs)

The importance of fouling(fouling costs)

First of all, fouling costs can be separated according to how they are generated. Roughly taken, there are four types of costs:

1)      Additional capital costs or costs for special design considerations

Lots of costs in using heat exchangers can be prevented in the R&D departments of a company. Especially when it comes to fouling. A good design can reduce the effects of fouling and thereby the operational costs of the heat exchanger. But of course research and design costs money.

A way to prevent fouling is to choose a bigger heat transferring surface then needed, as discussed before. The heat exchanger will become bigger and heavier, and thereby also more expensive.

2)      Energy costs

A heat exchanger that suffers from fouling needs additional energy to keep operating at the same level. This is because the fouling layer decreases the amount of heat transferred as well as it increases the amount of pressure drop needed to maintain the same throughput through the smaller cross-section. All this additional energy is pure loss.

3)      Maintenance costs

A fouled heat changer has to be cleaned once in awhile, in order to keep the energy needed for operation low. This cleaning can be online or offline, mechanical or chemical, etc. Sometimes it’s needed to replace some parts of the heat exchanger, for instance because of corrosion.

4)    Costs of loss production or shutdown costs

When a heat exchanger is cleaned or maintained offline, there is no production. No production means no income, so this is considered a loss. The effect of this shutdown depends on the normal plant capacity and the length of the shutdown. In recent years many research has been done to know more about the magnitude of the costs mentioned above.