Flow Measurement Accuracy Impact on Profitability

A common theme found in my 2008-blog posts was energy efficiency. Given the state of the global economy, 2009 posts will likely have a common theme on ways to improve profitability through cost savings and productivity increases.

Just before the holidays, my email spy service found a new flow measurement paper written by Emerson’s Bert Konings. The paper, Accurate Flow Measurement Improves Profit, describes flow measurement and its direct impact on the profitability of process manufacturing plants. He sums up the importance of flow measurement:

Get it right, and the plant is more efficient, produces less waste, minimizes rework and lowers maintenance costs. Get it wrong and the consequences can be significant. Inaccurate measurement in fiscal applications can lead to a plant being overcharged for raw materials or effectively giving away the product. Inaccurate meters used to measure utilities can also add to costs. Meters used to provide a mass balance across the plant need to be accurate or technicians will either spend time chasing product losses that aren’t there, or they will set the tolerance so wide that product losses are not identified early enough.

As I’ve discussed in earlier flow measurement posts, the technology choices are plentiful. Bert describes the pros and cons of many types including differential pressure across an orifice plate or venturi, positive displacement (turbine meters, oval gear meters), ultrasonic, vortex, and Coriolis mass flow.

Bert describes Coriolis measurement as being:

…based on the principle that when fluid is moving through an oscillating tube, forces are induced which causes the tube to twist. The amount of twist is directly proportional to the mass flow rate of the fluid flowing through the tube.

What has made the Coriolis measurement technology popular is its high accuracy and lack of moving parts. High accuracy helps the quality, throughput/productivity side of a plant’s economics. Maintenance costs are helped by the lack of moving parts. As Bert notes:

By selecting the right materials for an application, the effects of erosion and wear can be avoided and maintenance reduced to virtually zero.

Other advantages include direct mass measurement, online density measurements, high repeatability, and low pressure-drop across the meter.

A drawback to retrofitting other flow measurement technologies with Coriolis measurement has been the need for four wires (or up to 9 based on automation supplier.) Running additional wires and conduit is often an expensive proposition, $20 USD / foot according to one U.S. Chemical manufacturer. The Micro Motion team addressed this in 2008 by releasing a 2-wire Coriolis flow and density measurement meter. I discussed some of the applications for chemical manufacturers in an earlier post. Other industries and applications Burt lists are:

…suited for use in the chemical, petrochemical and refining industries, and for continuous process and mass balance applications.

Give the article a read if you’re weighing flow measurement options.

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