Dense Phase Conveying Of Pharmaceutical Ingredients

A typical application for a vacuum conveying system on a primary pharmaceutical site is the loading of ingredients into a reactor vessel or mixer. Often times, some ingredients need to be blanketed by an inert gas (usually nitrogen), due to a potentially volatile or explosive nature, dictating the exclusion of oxygen or moisture from the reactor. In these instances, "dilute phase" conveying systems are not suitable, as they rely on a flow of gas to convey the product, and if this gas needs to be nitrogen, the quantities required for bulk transfer would become prohibitively expensive, and difficult-to-handle/contain.

To handle these situations, the Quadro Vac® can be designed for "dense phase" conveying. These systems incorporate a vacuum-rated hopper, sealed at each port with a valve, and the fan or blower used on lean phase systems is exchanged for a vacuum pump, capable of reaching high levels of vacuum. Vacuum is drawn on the hopper with the transfer and discharge valves closed. The vacuum line is then closed, and the transfer valve opened, drawing product up the lance and into the hopper, until the hopper returns to atmospheric pressure. The discharge valve between the hopper and reactor vessel is then opened, and the product falls under gravity. As long as the product is blanketed at the supply point, then there is no risk of product contamination during transfer, and the use of high vacuum rather than gas flow for conveying, keeps the quantity of inert gas used to a minimum.

Generally, as these applications are hazardous due to the presence of flammable vapors and dusts, control systems use air logic controls, and all equipment is classified in accordance with ATEX guidelines.

SOURCE: Quadro Engineering Corp.