Nowadays, pneumatic suction conveying is an important technology for feeding bulk goods gently through piping systems to the various process steps. In the area of food processing, the pharmaceutical and chemical industry and for material feed in plastics processing, suction conveying is indispensable when powder or granular materials have to be transported. The proper choice of the vacuum generator essentially determines the operating costs of a pneumatic conveying system.
In open end pipe line suspension flow, or dilute phase pneumatic conveying, proper particle velocity is critical to continuing productivity and product quality. Until recently, measurement of actual particle velocity within the pipe has not been practical outside the laboratory. The plant operating personnel depend on a much less accurate metric - estimating the conveying air velocity in the pipe and relating that to particle velocity.
Pneumatic conveying applications are critical to many facilities – when you can’t move material you can’t make or sell your product. Because of a historical lack of availability of specialized rental blowers and air compressors for pneumatic conveying, plants often either accepted the production outage or rented a more readily available two-stage, oil-free rotary screw air compressor designed for 90 to 150 psig plant air service that is very inefficient at the reduced pressures needed for pneumatic conveying.
This article reviews two common pneumatic conveying system types and the importance for each operating plant to know their design and operating parameters particularly conveying air flow velocity and particle velocity profile.
During the summer season, vegetables tend to deteriorate quickly once harvested from the field—or during postharvest stage of the cold chain. In traditional cold chain systems, vegetables are put into a chilled cooler for preservation, a process that requires approximately 12 hours for the product to achieve proper temperature. In some instances, as much as 25 percent of food product in the chilled cooler will decay before arriving at a proper storage area. Fortunately, there is a process for improving the effectiveness of the postharvest stage—vacuum cooling.
Formaldehyde is an organic compound that can adopt several different forms. It can be used in solution form as formalin, as a free gas, or in a solid form as paraformaldehyde prills. Formaldehyde is highly toxic to humans, regardless of the method of intake. At room temperature it is a colorless gas characterized by a pungent odor. Even with very short-term exposure, formaldehyde will cause irritation to the eyes including pain, redness, blurred vision followed by sneezing, soreness, coughing, shortness of breath, headaches and nausea. Exposure to elevated levels can lead to accumulation of fluid in the lungs (pulmonary edema).
It’s one thing to move materials during the production process, but when it’s a finished product on the packaging line, choosing the right material handling system is essential. Getting it wrong results in squandered production time when product loss occurs, and wasted raw materials.
Nutriom sets the bar high when it comes to producing its premium quality natural powdered egg products Ova Easy® and Egg Crystals®, that are sold at outdoor retailers such as REI, and online merchants such as Amazon.com; so, when the screw conveyor in their FSIS USDA facility required regular unexpected attention, Leonardo Etcheto, Plant Manager at the Lacey, WA facility knew it was time to look for a better solution.
The plant air system consists of eight, single-stage, lubricated, Sullair rotary screw compressors. All units are in good working order. Units 2, 3, 4 and 7 are water-cooled and units 6, 8, 9, 10 and 11 are air-cooled. The main plant air system has two primary compressed air dryers, a Thompson Gordon model TG 2000 refrigerated dryer, and a Sullair model SAR 1350 heatless desiccant dryer. Both units are working according to their design. The TG 2000 uses approximately 11.2 kW and is a non-cycling type unit, and the SAR 1350 uses approximately 200 cfm of purge air to regenerate the wet tower.
In thermal power stations, nuclear plants, and chemical and industrial plants, different types of bulk materials are used. The materials exist in different forms including lump, powder, granules, chips, and pallets. These bulk materials, in their different forms, require efficient and reliable material handling systems.
In many manufacturing operations, a very significant compressed air use is pneumatic conveying of many types of materials such as cement, fly ash, starch, sugar, salt, sand, plastic pellets, oats, feeds, etc. Often these are systems that use high-pressure air (100 psig class) reduced to lower pressures (15 psig, 45 psig). This creates an air savings opportunity.