A manufacturer of vitamins uses a tantulum flowmeter to dose Toco Toluol, a highly aggressive and acidic solvent, into a column. The liquid, with a density of 0.881 kg/L and a temperature of 78°C, is measured over a mass flow range of 0–7000 kg/h at a pressure of 1.8 bar.
A Tantalum flowmeter was necessary in this application for its chemical resistance. The customer opted for the Krohne’s Optimass 7300 C Tantalum flowmeter over other, previously used Tantalum meters because of its single, straight measuring tube, eliminating the need for a flow splitter. The straight tube allowed the customer to select a significantly smaller diameter (DN 25, instead of the DN 50 used previously), thus achieving an increased flowrate and avoiding the deposition of the product on the inner wall of the measuring tube.
The recent availability of Tantalum has allowed manufacturers to offer Coriolis meters for the measurement of highly aggressive or corrosive media. However, the twin U-tube design is costly, since both measuring tubes, as well as the flange and flow splitters, are made of Tantalum. Krohne’s straight, single-tube design requires only the measuring tube and the seal to be constructed of Tantalum, resulting in considerable cost savings compared to twin U-tube meters.
Though Tantalum does not have the same tensile strength as the traditionally employed Titanium, Krohne uses a special alloy to address this issue. The alloy, designated Ta10W, consists of 10% Wolfram and 90% Tantalum. The portion of Wolfram guarantees the higher measuring tube stability that is necessary for a straight-tube design. The chemical resistance of the alloy is comparable to that of glass.
In addition to Tantalum, Krohne supplies the Optimass series in a variety of materials for use with aggressive media, including Hastelloy C22, Duplex steel 318L, Titanium and 316L stainless steel.
Krohne, Nordrhein-Westfalen, Germany
Hall 10.2, Stand F25-J31