Problems with the Use of Pneumatic Screw Pumps to Transport Bulk Cargo

Abstract

An analysis is made of the performance of pneumatic screw pumps at the Bereznikovsky Soda Plant in order be able to transport light soda along a prescribed route and make use of a new nozzle section to make the pumps' operation more reliable. Specific recommendations are made to increase the throughput and reliability of pneumatic screw pumps. The expediency of replacing long lines of screw pumps by chamber pumps is also discussed.Keywords: pneumatic screw pump (PSP), productivity, light soda, transport pipe, compressed air, nozzles, modernization.Continuous pneumatic screw pumps (PSPs) are designed to transport dust-sized or fine-grained materials along a conduit by means of compressed air. Pneumatic rotary pumps are used as feeders in the pneumatic conveyors employed by cement plants for the in-factory transport of cement. They serve the same function in plants that make ferroconcrete products and in factories that make products used in home construction. PSPs are also commonly used at plants in the chemical, metallurgical, glass, and cellulose-paper sectors, among other industries. There, they are employed in pneumatic conveyors that transport calcined soda, sodium sulfate, alumina, potassium chloride, phosphates, ash, coal dust, ores in powder form, fertilizers, and many other materials. The PSPs currently being built in Russia can convey materials over a distance of 230 -430 m, including 30 m vertically [1 -3].At present, Russian industry makes four main types of PSPs. They range in capacity from 10 to 100 tons/h. The design of these pumps was initially the same as the design of the pumps made by the "Fuller" company in the U. S. The design of the main working elements of the Russian pumps was later modernized so as to significantly improve the pumps' service characteristics, durability, and reliability.When operated under normal conditions and given the proper maintenance, pneumatic screw pumps perform reliably over many years. On the average, PSPs last more than 10 yrs. Among the parts of PSPs that wears most rapidly is the fast-moving pumping screw. The length of the period of continuous operation of the screw is within the range 50 -1000 h, depending on the type of electrodes used. The bronze sleeve and the disk of the check valve undergo considerably less wear. The gland packings in the latest designs of the seal of the screw's shaft average 300 -350 h of continuous use. To optimize the service life of the parts that wear quickly, it is necessary to regularly check the condition of the corresponding components.The wear of the screw is determined by periodically measuring the gap between it and the sleeve. When the size of this gap reaches 5 mm, the screw should be replaced and the worn screw reconditioned by hard-facing its turns with VSN-b electrodes. Electrodes of the T-590 or T-620 type can be used if VSN-b electrodes are not available, but such a substitution will result in a nearly twofold reduction in the remaining life of the screw. The hard-facing operation should be performed by a qualified we...

Control algorithms and signals of the pnevmotransport system stations at the enterprises of the mining and metallurgical complex

“…Существующие системы пневмотранспортной доставки грузов по транспортным трубопроводам отличаются большим разнообразием схемотехнических решений и различными областями применения [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], однако, требуется адаптации узлов этих систем к процессу транспортировки технологических продуктов в условиях горного, обогатительного и металлургического производства.…”