Adding Versatility to Your Air to Put Your Materials in Motion
When companies have powders or dry bulk materials that they need moved through their plant that is both cost-effective and results in minimal loss of product, pneumatic conveying is an efficient solution. For years, industries in pet food, specialist materials, food and beverage, and chemicals have utilized pneumatic conveying systems as a method of moving their materials through enclosed pipelines using the power of versatile air generated by blowers and compressors.
Kice Industries has been in the dilute phase of pneumatic conveying for over 50 years and has covered a number of materials. This includes wheat flour, corn meal, soy meal, whole grains, spices, wood products from chips to flour, plastics from virgin pellets to regrind, meat by-products, and many more commodities.
Obviously, different products require different types of pneumatic conveying systems. Many materials can be conveyed in positive pressure lines while some products require vacuum conveying. Normally, pneumatic conveying is used simply to transport a material from a pickup point to a destination. Other times, products may require a specific amount of conveying air to cool the product, keep hammermill screens clean, or potentially convey aspirated products to a destination. You will find that pneumatic conveying is extremely versatile for moving a product through your plant, which is why so many plants around the country use this exact type of system.
The distinct advantages of pneumatic conveying for companies needing to move bulk materials include:
- The ability to route the system around existing equipment inside your plant or facility; pneumatic conveying systems can be built to run both horizontally and vertically, making it one of the most versatile solutions to moving bulk products.
- The benefit of protecting the product from outside contaminants; since the product is enclosed in the pneumatic conveying system’s ducts and piping, there’s no chance of it being compromised.
- Compared to mechanical conveying systems, pneumatic conveying systems are more cost-effective and are far easier to maintain due to the lack of moving parts; they also take up less floor space.
- The convenience of having multiple points in the system where products can be discharged or introduced.
POSITIVE PRESSURE SYSTEMS: BREAKING DOWN HOW PNEUMATIC CONVEYING WORKS
The most efficient and simple method of pneumatic conveying is by using a positive pressure system. To simply convey a product from point A to point B generally requires a positive pressure blower package, rotary airlock, a cyclone receiver (sometimes an airlock valve) and the tubing system with elbows, sight glasses, and couplings. Normally, the exhaust air from the cyclone receiver will need to vent to a secondary filter, scrubber, or into the atmosphere.
One of the features of a positive pressure system is that you can add pickup points and go to multiple destinations. Simply add in line diverter valves to the conveying line and pick any one of several destinations. There are various methods of discharging to a number of destinations. Another feature of positive pressure conveying is that with planning and engineering you can actually loop a system and reuse the same air to convey the product to a second destination in series. However, this is not always recommended and requires special design.
Normally, positive pressure systems use PD (positive displacement) or constant displacement blowers. Generally, these blowers are rated to 15psig, although a few may be rated lower or higher. Kice Industries rarely designs systems to work at pressures greater than 10psig. The major reasons for this are dependability, heat considerations, stress on couplings, and component equipment. Most systems are expected to run 24 hours a day/7 days a week, which places considerable stress on a relatively small piece of equipment with high input horsepower. Also, if the system is designed to be maxed out at all times there is nowhere to go if you need to increase the conveying distance or capacity.
VACUUM PRESSURE SYSTEMS: THE MOST SANITARY METHOD OF MOVING PRODUCT
The second popular method of conveying is by vacuum. There are a number of reasons for vacuum conveying as opposed to using a positive pressure system. One of the first considerations is that it is largely considered to be more sanitary. There is no bypass air from the feed in the airlock or leaks in the piping system, which maintains the integrity of the materials being moved. Oftentimes, the conveying air is also used to cool the product and help the efficiency of a grinder or extruder. Generally speaking, the vacuum system is not as efficient on horsepower or air volume requirements as a positive pressure system, but the benefits mentioned often offset this disadvantage. In most cases, vacuum conveying systems use centrifugal fans that normally work in vacuum ranges of 20“wg to 40“wg. This means the air system will be considerably larger than a positive pressure blower system working in the 4-9 psig pressure range. When using centrifugal fans, cyclone receivers are sufficient from a clean air point of view.
Sometimes the positive displacement blower will be used for the vacuum air mover. This type of system will work in inches of mercury “HG” and normally ranges from 6“hg to 12“hg. The deeper vacuum allows much higher capacities over the centrifugal fan for a given line size. This system is often used for conveying away from rail cars where clearance under the car is minimum and capacity is critical. The disadvantage to this system is that the PD blower can only digest very small amounts of dust, so a filter receiver is normally required rather than a cyclone receiver. Please contact Kice Industries for questions pertaining to dust collection equipment and how to get a dust collector installed in your warehouse or place of business.
WE’LL MEET YOU WHERE YOU ARE
There are numerous variations and combinations of vacuum, pressure, and vacuum/pressure conveying systems. It takes experience and innovation to figure out what system is going to be the right for you and your materials. We at Kice welcome the opportunity to visit and work with you on your requirements. If you have any questions please do not hesitate to contact us and one of our project designers will be happy to discuss your requirements with you.