What are the reasons for blocked conveying lines?
All pneumatic bulk material handling systems block sometimes. Clearing a pipeline means downtime, loss of production, and can be a maintenance headache. So ensuring your system runs as smoothly as possible day after day is critical. Lion Bulk Handling, together with her brands, have been designing pneumatic conveying systems for more than 50 years, using our knowledge and experience to design systems that aim to provide the most reliable and maintenance free systems possible. We do not like blockages or any other maintenance issues any more than you do. But if they do happen, understanding where to look to minimize downtime is essential.
Here are some tips and tricks for a quick recovery:
- Changes to controls – Sometimes it is essential to modify PLC programming. For instance, adding additional distribution valves, changing the requirements of the clean-up procedure, changing the through put of cargo. Any control changes should be carried out in conjunction with the system manufacturer. If not, the customer may inadvertently change some of the basic settings, times etc. fundamental to the operation of the pneumatic bulk material handling system.
- Out-of-Specification Material– Has your material changed? Is the bulk density, particle size distribution and flow ability what the system was designed for? If the answer is no, the blockages could be explained by the material.
- Foreign Material– Sometimes foreign objects such as used welding rods, cigarette packs, wire, nuts and bolts, robs, etc. find their way into the cargo holds, silo, hopper or any other storage facility. As these materials accumulate they create a blockage preventing the conveyed material from entering the conveying line or moving along down the pipeline.
- Moisture in the conveying process– Moisture can change the material characteristics. Materials will become sticky or poorly flowing resulting in conveying blockages. For instance, with temperature change there is the possibility that water or steam may enter the cargo holds or any other storage facility. You should realize that moisture in the atmosphere can appear in three states–solid, liquid, and a gaseous vapour. It is very rare when the air does not contain some water vapour. When the air is cooled to its saturation point, condensation occurs. As most types of the dry cargo, such as fly ash, cement, barite, etc. are hygroscopic (they absorb moisture from their surroundings) moisture will change the consistency of the dry cargo will create conveying difficulties.
- Air Supply Problems – If the air supply to the conveying system has inadequate pressure, flow and/or contains too much moisture, this can cause the material to slow down in the pipeline. Usually this causes the pressure to rise and if the air supply pressure cannot be maintained through the cycle, the system will block.
- Pipeline Incorrectly Installed – Any changes to the original pipe route configuration can cause blockages. If you have a need to modify a pipe route contact the supplier for verification or for re-configuration and resizing of your system.
- Receiving hopper High Level indicator Failure – Check the operation of the level indicator if fitted. Level indicators are installed to signal the system that the receiving tank, hopper, hold or silo is full (i.e. when the indicator is contacted by material) and to shut the system down until the indicator is uncovered. Faulty level indicators may allow the system to keep on conveying material to the tank, hopper, hold or silo and over fill it. If noticed by the operating personnel, the system will continue to convey, gradually filling the pipeline until it blocks.
If you have problems with blocked pipelines or other issues with your bulk handling system, then contact our service team. Our Lion Bulk Handling Team are ready to inspect your system and solve the problem. If you have any questions, please do not hesitate to contact us.