MechChem Africa July 2018

⎪ Products and industry news ⎪

What is a ‘Roots’ type pump?

Waste management outlook for Africa

The Roots type blower is a positive dis- placement lobe pump, which operates by pumping air with a pair of ‘meshing’ lobes via a pair of synchronised gears, driven by an electric motor, either directly or via V-belts. Air is trapped in pockets surrounding the lobes and carried from the intake side to the exhaust. It is used to pump large volumes of air at pressure levels (P) up to 900 mbar or maximum vacuum levels (V) of -500 mbar. There are a few blower de- signs such as the twin-lobe roots, tri-lobe and four-lobe ‘Roots’ blowers. Currently, the most commonly sold units are the tri- lobeunits, whichoffer noise reductionand a reduction in pulsation. Inlet/outlet sizes range from50mmup to 500 mm (larger units may be available) with flow rates from, in pressure applica- tions, from 100 m³/hr up to 25 000 m³/hr, and for vacuum applications, capacities from 100 m³/hr up to 5 000 m³/hr are typical. Vertical andhorizontal inlet/outlet flowoptions areavailableby simply chang- ing the position of the feet. Standardunits aremade fromcast iron and ductile steel, but units with ‘wet-end’ in316 stainless steel are available andone can get special internal coatings as well, depending on application requirements. Onemay purchase the units as ‘bare shaft’ A new low profile flexible screw conveyor from Flexicon, with an integral bin and castor-mounted frame can roll below mezzanines and other low-headroom areas, receive material from overhead equipment, and discharge the mate- rial into process equipment and vessels throughout the plant. Ready to plug-in and run, the self- contained unit features a ‘push type’ drive system positioned at the lower intake end of the conveyor, versus a standard ‘pull-type’ drive positioned at the upper discharge end of the conveyor, reducing overall height by approximately 610 mm. At 250 ℓ , the integral bin accom- modates the contents of approximately one-third of a bulk bag measuring 1×1×1 m, or several typical 25kgbags, depending on bulk density. AspecialisedBEV-CON™screwwithin the straight conveyor tube is engineered tomove a rangeof difficult-to-conveybulk materials that tend to cake, pack, smear or plug, as well as fragile products prone to breakage, with no separation of blends.

Recyclingonly4%of thewaste it generates, Africa has become a dumping ground for waste, par- ticularly hazardous waste, often from developed countries: a far cry fromtheAfricanUnion’s vision that “African cities will be recycling at least 50% of the waste they generate by 2023”. This and other findings are outlined in the re- port releasedby theUnitedNations Environment and the Council for Scientific and Industrial Research (CSIR) on World Environment Day on June 5 during Sustainability Week in Pretoria. The consolidated waste management out- look publication is the result of contributions by experts and researchers from across the African continent, and provides an analysis of the state of waste management in Africa, its impact on the continent and proposed solutions for improving waste management in the region. The regional outlook is the latest in a series of waste management outlooks, which began with the ‘Global Waste Management Outlook’ in 2015, published byUnitedNations Environment, through its International Environmental TechnologyCentre (IETC) in partnershipwith the International Solid Waste Association. The IETC is partnering with regional experts to address region-specificwastemanagement outlooks that provide policy recommendations and solutions based on current practices in developing and developed countries. Professor Linda Godfrey, principal scientist at the CSIR, was the coordinating lead author of the publication. Godfrey highlighted the need for Africa to start addressing current poor waste management, saying that itwas having a negative impact on the economy, society andenvironment. “There is an urgent need for African coun- tries to address the current waste management challenges and to prepare themselves for the ex- pected growth inwaste generation in the coming century. Thiswill require social and technological innovation and investment in services and infra- structure in the waste and secondary resources sector at levels not yet seen in Africa,” she says. Head of UNEnvironment Programme, Cecilia Njenga, said the uncontrolled dumping of waste is one of themajor challenges facing Africa. “This is a momentous time for Africa,” she said. “The Report sets a vision for Africa and we hope that this document will inform and inspire decision makers around the continent to preserve the environment”. The ‘Africa Waste Management Outlook’ will be available as a free download on the websites of UN Environment and the CSIR: www.csir. co.za/documents/africa-wmo-report.pdf and the outlooks of other regions are also availableon the UN Environment website. www.csir.co.za

Roots-type blowers are widely used for

air compressor applications as well as for rough vacuum applications where the volume of air moved is large compared to its pressure. units or packaged systems complete with motors, with or without sound-reducing cabinets for both indoor and outdoor use. These blowers are widely used for air compressor applications as well as for rough vacuum applications and are typi- cally used where the volume of air moved is large compared to its pressure. The greatest benefit of these blowers is that they are used in applications that require constant air flowrate at varying discharge pressures, for industrial applications such aswater/sewage treatment plants, central vacuum cleaning systems, blending, ef- fluent treatment plants, water treatment plants, dewatering, air drying, biogas and pneumatic conveyance of powders or plastic granules, to name just a few. www.vactech.co.za Except for the polymer tube, all mate- rial contact surfaces are of stainless steel finished to food, pharmaceutical, dairy or industrial standards for rapid wash down and/or corrosion resistance. Flexicon also manufactures bulk bag dischargers, bulk bag fillers, pneumatic conveying systems, tubular cable convey- ors, manual dumping stations, drum/box/ container tippers, weigh batching sys- tems and automated plant-wide systems integrated with new or existing process equipment. www.flexicon.co.za

Low-profile flexible screw conveyor

Flexicon’s low profile, mobile flexible screw conveyor with integral 250 ℓ bin and straight BEV-CON™ screw.

July 2018 • MechChem Africa ¦ 43