These are five dreaded words that no engineer wants to hear on a Saturday night or Sunday morning: “The filtration system is not working.” Of course, we never seem to get this call at 10 in the morning on a work day!
No matter the time of day, let’s not panic, take a deep breath and begin the analysis.
There are normally three main areas that must be examined when you learn the filtration system is not working:
- The filter itself for mechanical reasons
- The equipment around the filter is not working
- The filter operational procedures are not correct.
To fully understand the problem, it’s necessary to separate the symptoms from the causes. So, let’s examine each of these groups in more detail.
Troubleshooting Filter Problems
The first thing that should be checked is the filter itself. There could be a failure of the equipment mechanics such an internal components, seals, etc. Many of these issues will be described normally in the preventative maintenance section of the filter’s O & M manual.
Second, keeping in mind, the filtration system is part of the entire process it’s important to examine the upstream and downstream equipment. For example, you might check:
- Are the reactors performing correctly in terms of agitation, temperature control, etc. in order to produce the specified crystals?
- Are the precoat and body feed systems in tune for mixing, feeding, flow rates, solids loading, etc.?
- Are the valves and instruments operating correctly and reading the correct variables (calibrations), etc.?
Next, take a look at the pumps that feed the slurry and washing liquids as well as the compressors the feed the gas streams for drying and cake discharge. The pumps must produce the required pressure, flow rates, etc. The compressors must also produce a certain gas flow at a specific pressure for a certain amount of time. Are their interlocks in the control system or a control communication problem that are not being recognized that are causing the filter problem. Finally, if flocculants and chemicals are being used, have these changed?
Process Engineering Problems?
The last place to look is the process or operational procedures. These could be responsible for the filtration problems. For example, the particle size distribution may have changed, the amount of solids in the slurry may have changed, the cake compressibility may have changed, etc. In terms of the operation, has the filtration pressure changed, timers changes, speed changed, etc.? Finally, determine whether or not a process parameter has changed.
Trouble shooting is not easy, but solving the problem brings a great sense of satisfaction.
Let me know some of your troubleshooting horror stories! I’d love to share some in a future blog. Together, we can make it easier to handle the situation next time we hear those five dreaded words.