TACKLING TOUGH SERVICES
The chemical industry increasingly is taking a "fit and forget" approach to vacuum systems, says Bolton, U.K.-based Don Collins, market development manager – chemicals for Edwards, Sanborn, N.Y. "Like utilities, you want to start it off and forget all about it." In response, the company has launched a line of dry vacuum pumps called CXS that boast innovative screw design and temperature control (Figure 2). "The CXS is intended to bring improvements to even the best vacuum pump on the market. These include better solids- and liquid-handling capability without special measures, longer service intervals (up to five years before any service), low noise (<64 dBA), integral control and best-in-class cost of ownership," notes Collins.
"The range is aimed at the nastiest chemicals that can be pumped, including aromatics, benzene, halides, vinyl chloride, acids and flammable materials, together with a limited amount of solids," he adds. Site tests particularly are targetting difficult applications. The toughest of these involves pumping phenol. Here a CXS pump has been installed side-by-side with an existing Edwards EDP dry pump. The EDP doesn't have an upsteam knockout pot (KOP) with automatic drain to prevent large liquid slugs from tripping the pump from time to time. If the pump cools down and phenol solidifies within it, the unit can suffer damage upon restart. This happens two or three times a year, primarily due to an incorrect manual KOP draining procedure.
"The CXS has taken these same slugs without tripping and, even when stopped unexpectedly, for example during an emergency plant shutdown, it restarts without damage even after it cools down. This is exactly what we expected from the pump. It has been running well for several months in this condition, so we have extended the trial," notes Collins.
In trials at a chemical plant in Italy, the low noise level has proven to be an important factor. Electrical engineers there also have praised the pump's ease of installation: the CXS comes with its own controls and hardwired safety interlocks and software and just needs the power, water and pneumatics connected to be up and running. It can be remotely monitored and controled via several communications interfaces including Ethernet. "What we would like to do in the future is to make the control system even better, for example by including software for its own predictive diagnostic testing."
Piab USA, Hingham, Mass., is promoting the benefits of miniaturization and decentralization in vacuum system design. For instance, the company has introduced a new concept for vacuum conveying of powders. Its piFLOWi design promises to allow users to double the conveying capacity for many materials.