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From Powder and Bulk Dot Com Controls
The mechanical handling and conveying equipment for the product in process is extremely critical due to the linear process. Therefore, if one step in production fails the whole process backs up and ultimately has to stop. Cement production operates with limited manpower – if a problem occurs, such as a blockage, there is often nobody around to raise an alarm. A plant can take days to re-start thus a simple stoppage can soon account for many thousands of tons of lost production. Cement or raw meal is difficult to clear up and it is common that plants would resort to manual labor to dig out elevators or conveyors. Given these challenging conditions, cement plants require reliable instrumentation to confirm that conveying equipment is running correctly and capable of transferring material. A leading cement company in the United Arab Emirates (UAE), is a major regional cement producer and employer of more than 500 people. The company produces and distributes cement in bags and in bulk. This producer has an installed annual production capacity of 2.5 million tons cement and 1.3 million tons clinker. The company plans to increase annual production capacity to 3.8 million tons and is currently constructing new plants beside their current location. The proximity of the plant to the Arabian Gulf offers the advantage of direct loading of bulk cement to ships at a rate of 550 t/h (around the clock) through a unique pneumatic system. As well, the plant is only 550 m from the foot of a limestone quarry that forms more than 80% of the raw material of cement manufacturing. This ensures a steady supply of raw material for cement production. Challenge This company provides cement on large, complex and demanding projects for public and private customers primarily in the UAE and Arabian Gulf Zone. Recently, they have undertaken numerous landmark infrastructures, industrial and commercial projects. Therefore it is critical that around-the-clock production is maintained and costly downtime is minimized. It is essential that conveying equipment operates properly and that blockages do not occur. In particular the screw conveyor on the cement filter collector must be continually monitored. The cement needs to be continually removed from the collector to prevent blockage of the filter process. Any stoppage of the screw conveyer would cause material to build up and the filter operation to fail. Ultimately the excess material would need to be manually removed before repairs could be undertaken. Without proper monitoring, several hours may pass before a fault in the filter collector would be identified through a secondary effect. Solution Based on Siemens reputation for reliability and success, the company chose to install the Milltronics MFA 4p motion sensor to monitor the operation of the screw conveyor on the cement filter collector. The MFA 4p is a highly sensitive single set point motion sensor system, used with remote sensing probes. The MFA 4p detects changes in the motion and speed of rotating, reciprocating or conveying equipment. It warns of equipment malfunction and signals through contacts to shut down machinery in case of a slowdown or failure. Its reliability makes it a cost-effective way to protect valuable process equipment. The single set point system is ideally suited to cement industry applications. It can be easily retrofitted to existing equipment using Form C contacts from one or both of the two relays, to wire directly into the equipment's motor starter control circuit, or provide a dry contact to a digital input of the plant control system. A special feature of the MFA 4p is the adjustable 0 to 60 second time delay, allowing the monitored device to accelerate to normal running speed before monitoring begins. A wide range of probes is available to suit specific needs, including high temperatures, corrosive environments and dust approvals. Benefits This cement producer now has reliable monitoring for the cement filter collector. The MFA 4p is able to detect the movement of the flights on the screw conveyor. With its long (100 mm) sensing range, the MFA 4p probe can sense the movement of ferromagnetic objects. The Milltronics MFA 4p probe offers the advantage of detecting movement, rather than the just the presence of a ferromagnetic object. The non-contacting technology means virtually no maintenance or cleaning is necessary. The MFA 4p is east to install and provides superior cost-effective protection. This type of process protection system acts as an early warning system to avoid costly process interruptions and breakdowns of equipment. Source: http://www.siemens.com/ © Copyright 1998 - 2011 Powder and Bulk Dot Com |
