The operation of a pneumatic unloading system is based on an airtight closed loop interaction between multiple components like, valves, instrumentation, PLC, compressors and possible vacuum pumps. It is of vital importance that all of these are working without any delay, incident, resistance or leakage for gaining an optimal balance between energy consumption and convey capacity.
Once a pneumatic convey system is delivered and commissioned all components are new and interacting as designed whereas the maximum performance is still achieved. However, over age and running hours, at least the components that are in direct contact with the conveyed bulk material are met normal wear and tear. Meaning that the convey performance is negatively influenced by the condition of these components which therefore need to be checked on a regular basis for maintaining a good and optimum condition of the system.
Such inspection can easily be done by the operating crew, we have made a common checklist which might be handful for your crew to start 2018 with a good working system. Note that some items mentioned below might not be applicable for your system as there are a variety of component designs/layout for pneumatic conveying.
Step 01 (basic visual inspection without running the system)
- For enable to visual see any short comes, leakages or damages make sure that the convey system and her components are clean and dust free
- Multiple components are operated by either pneumatic air or electricity, make sure that pneumatic hoses and electrical wires are not leaking or damaged
- For running components like diesel engines, compressors, blowers and vacuum pumps check the condition of the oil and filters. Follow the maintenance guidance schedule for replacing the oil with the recommended type and volumes.
- Drain any water separators according the maintenance guidance
- Inspect the fabric on the air slides, tank bottoms and vessel floor on damages or leakages
- Inspect air filters inside re-loader tanks/kettles
- Mechanical safety devises like pressure relieve valves can be in most cases manual operated by a lever for confirming the working. As these devises only come into action during problems, which with a healthy system would be very rare and might be stuck when needed due to build-up of debris, dust or rust.
- Start-up the PLC and HMI for witnessing any actual alarms or indications. Troubleshoot on the faults and review the alarm history for being aware what were the common frequent attentions needed previously. Clear the alarm log and make sure no alarms are active
Step 02 (operational inspection without conveying material)
- Many instrumentation and position indicators are providing the necessary information to the PLC, test each individual by manual override for making sure that the signal is received by the PLC and shown on the HMI at the correct location in the process or mentioned by name
- Same goes for the signals from the PLC to the field equipment, are these still send and received at the correct component?
- As all digital signals from and to the PLC are checked and confirmed, we can operate each individual valve, cleaning system, motor, fan, blower, compressor, vacuum pump, etc. for witnessing a problem free operation and indication
- For the manual operated components like manual valves, gears, manipulator arm, hoists, etc. operate each single item for a correct working
- Shut down all running equipment for witnessing any oil/water spill, leakages or dust after this maintenance and test-run
- After no indications of any problems or faulty indications on the HMI, we can perform a “leak-test” for making sure that all related valves to the tanks/kettles are no leaking “false” air. This can be done manual or by the PLC after running the compressor(s) and start discharge operation cycle. Let the pressure reach approximately 1 bar in a particular tank/kettle and push for the stop command or close the pressurization valve manual. Now the pressure is “locked” inside the tank/kettle and may be witnessed by the HMI or pressure gauge. As there is continuously some minor internal leakage an acceptable indication that the valves are still in good shape, a pressure drop of 100 mbar per every 10 minutes is within margins. Less pressure drop is even better.
Step 03 (basic visual inspection with running the system with material)
- Continue operation now with material for a 1x full cycle through each tank/kettle/air slide and shut down afterwards for witnessing on leakages as multiple inspection covers have been opened and closed
- Check-up on oil filled components for leakages as the temperature in these components are rising
- Continue operation for 1 hour and shut down for a full visual inspection on oil, water and dust leakages
- Continue operation as normal
By executing the above steps, we have brought back the system in good and reliable running condition as it was delivered. In case the performance is lower and/or energy consumption is higher than as it was new, there are a variety of external factors that will influence this, such as: convey pipeline routing, clog up of fabric or air filters, pressure settings in the PLC, convey material specifications, temperature and moisture ambient conditions, operator skills, etc.
If you run into these limitations and would prefer to get some help, guidance, inspection, tuning & tweaking or training, feel free to contact us for support. Lion Bulk Handling offers multiple service packages for all bulk handling applications. Contact our service department for maintenance and operation advise for your application and/or book your free inspections.