TRADITIONALLY, process plants were designed to produce a single, specific product which resulted in a limited line of products unable to meet changing market demands for increased variety, lower prices and shorter lead times. Today multi-purpose plants are designed to handle several products.
An adaptation of recipes and the improvements in instrumentation functionality now allows for quick, accurate and safe changes of products.
John Immelman from Endress+Hauser looks at the development of integrated batching software in process instrumentation and some of the flow-on benefits.
Batching has been a part of the process production lexicon for almost as long as manufacturing itself. It is a complex task. Throughout the decades since the start of the industrial revolution the product combinations in recipes - the results of and the reasons for batching - have changed. But, if anything, the need for and importance of batching has increased.
In a manufacturing/processing sense, batching is the accurate and repeatable addition of pre-determined amounts of different products to form a mixture for further processing. As a function, batching is rapidly gaining importance as manufacturers look to expand and diversify product ranges.
Until fairly recently, the regulation of the various quantities of each component in a recipe was a relatively in-exact science. Typically a batching system consisted of a flow measuring device (a flowmeter) and a control device such as a valve or actuator.
Production managers knew how many grams or litres of each product were required, and to achieve the right amount sometimes saw a trial-and-error as the shut-off time of the valve was balanced against the extra product that was left in the pipe - product that would flow into the mix after the valve was closed.
And each change of product characteristic, such as viscosity or density, required more trial-and-error to get the quantities right. Inaccuracies in mixtures could occur through this manual and by comparative standards, expensive control method.
The importance of batching control and accuracy can be found in ready-to-drink (RTD) alcoholic drinks. Among other mixing parameters, these RTDs must be mixed with regard to the legal requirements for the correct alcohol content. Should the final product contain more alcohol than is legal, the manufacturer could be fined.
For some time devices to measure and record product flow have been available. If measuring conductive liquids such as water, milk, acids etc by volume (litre, gal) electromagentic flowmeters were used; if measuring non-conductive liquids such as hydrocarbons, demineralised water and waxes by mass (g, kg) Coriolis flowmeters were employed.
This is still the case, and although flowmeters assisted in developing greater accuracy in mixtures and recipes they had no functionality to control batching.
A system was needed that would give production managers in automated manufacturing and processing plants more accuracy and greater control over the primary fill (the bulk of the product) and secondary fill (the fine tuning to make up the right amount) parameters.
To meet demand, Endress+Hauser introduced sophisticated batching software for its new range of Promag 53 electromagnetic and Promass 83 Coriolis flowmeters.
The new software integrates seamlessly with existing operating programs and the flowmeters instantly become batch controllers, as well as providing the measuring tasks for which they were originally designed.
External batch controllers are rendered superfluous but, more importantly, the control function joins the realm of the flowmeter; the reliance on the PLC/DCS is broken with the establishment of an intimate partnership between a measuring device (the flowmeter) and a control device. This is the solution manufacturers are seeking.
Unlike the requirements of continuous flow measurement, absolute accuracy is of limited consequence for batching processes. The key requirement is repeatability.
For product and process consistency, and ultimately quality, the guarantee is for the required quantity, either mass or volume, at the appropriate time, on demand.
The Endress+Hauser designers developed integrated batching software that provides for up to 6 different, user-definable, pre-setable batching set-ups for 6 different products or for 6 different batch parameters and batch sizes - all of which can be set at the control panel on the flowmeter.
Each set-up can be tailored to manage the pre-batch, primary batch, secondary batch, number of batches, etc using a user-friendly interface and intuitive menu structure.
With batching software installed the functionality of controlling and managing the process is shifted to the field, close to the control device(s). This move dramatically cuts time involved in process management and also reduces the processing power required of the PLC.
The relocation of control also cuts the requirement for programmers, and saves on cabling installation and maintenance costs and associated labour.
Simultaneously, the evolution of enhanced hardware technology has benefited the batching process. Both magnetic volumetric flowmeters and Coriolis mass flowmeters are able to measure to within 0.1% of reading, using an increased variety of materials with chemical compatibility with more products under harsher conditions.
Ultimately, batching software provides a single, highly functional package which, as well as re-positioning and improving the process control for the overall benefit of the process, also delivers longer term operational and cost benefits to manufacturing plants in competitive marketplaces.
The Endress+Hauser integrated batching software provides for up to 6 different, user-definable, pre-setable batching set-ups for 6 different products or for 6 different batch parameters and batch sizes - all of which can be set at the control panel on the flowmeter.