North British Distillery Company
The North British Distillery Company was established in Edinburgh in 1885, making it one of Scotland’s oldest and largest Scotch grain whisky producers. The distillation and maturation business sells grain spirit – the base for blended whisky – and its byproducts.
When two of North British Distillery’s density meters failed within a week of each other, the plant’s engineers were looking for a modern replacement to measure the alcohol concentration of their product. Flow and density measurements are used to determine the alcohol by volume (ABV) percentage of the spirit, which in turn reveals the quality of the product and the efficiency of the process. But the distillery’s accuracy requirements (±0.1%), need for reliability and the high temperature of the process had proved challenging for other instruments. “The main problem we had with the old meters was that we had to calibrate them every shift because they kept on drifting,” explains Brynjar Ólafsson, Project Engineer at NBD. “If the temperature changed you had to adjust the meter, which happened regularly. I had looked at other meters, but they don’t have the same turndown ratios.
Historically, highly accurate flow and density measurement was only achievable under ideal circumstances. The Promass Q Coriolis flowmeter, however, has been developed for challenging applications in the food and beverage, and oil and gas industries. Mass and volume flow, density and temperature can be measured with one single sensor. “It helps me that I can get all the measurements from one intelligent meter,” confirms Brynjar Ólafsson. “We never had flow before, so we had to calculate how much spirit we were making by how much had gone in the vat.
“Endress+Hauser did an awful lot of trial work even before they came and installed them, which meant they were more accurate than the old ones. We were hoping for ±0.3% and we got to ±0.1%, which is quite nice,” says Brynjar Ólafsson.
Due to the success of the trial, NDB purchased a Promass Q for each of its four stills.
North British Distillery is now able to get an accurate reading directly off the stills, which are situated in an ATEX zone, and the Promass Q determines %ABV before feeding the measurements back to the company’s SCADA system. The highly accurate density and concentration measurement has improved product quality and efficiency, as Brynjar Ólafsson explains: “Now we know how much we’ve produced in spirit and how much we’ve produced in feints, which for us is off-spec spirit. You know which stills are performing, which ones aren’t, which ones you have to look at, where you’ve got a problem, where you don’t have a problem. It gives you clear information so you can manage your process better.”
The need for time-consuming daily calibration has also been removed. Promass Q is fitted with Heartbeat Technology, meaning the measurement can be verified without process interruption. “If it identifies an error, it comes up red,” says Brynjar Ólafsson. “So you just walk in the still hall and you know immediately it’s wrong. Part of the reason I went with Endress+Hauser is they’re willing to do the services quickly, which is the main thing that we need: we need the stills running.”