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When dry bulk solids are stored in closed containers, there is not only a risk of overfilling, but also a risk of dust explosions. The correct pressure relief must always be ensured, and at the same time the fill level must not become too high. Many operators make do with reinforced walls and other devices in case of an explosion. To prevent such an incident from happening in the first place, the only safe solution is to continuously monitor the fill level in industrial transport and storage processes.

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"Ensuring permanent accurate control requires continuous improvement processes in measurement technology," knows Frank Wengler, senior product manager and one of the engineers at MBA Instruments. "Only in this way have the rotating paddle detectors from MBA Instruments met the current highest standards in demanding measurement tasks for more than 70 years - not least for the safety of man and machine." The MBA800 measuring device was now given the chance to prove itself under extreme conditions.

Level measurement in hot gases

In biogas plants, organic waste, so-called substrates, are decomposed by bacteria in the absence of oxygen. This produces carbon dioxide, methane, nitrogen and even oxygen. For anaerobic fermentation, substrates are mixed in a pre-pit and then sealed in airtight boxes as a so-called fermenter. After escaping, a fermentation residue that remains can be used as fertiliser for agriculture. The biogas, in turn, is secured in a gas storage tank. The advantages of such a biogas plant: the unused organic waste can be recycled sustainably and the energy for a regional area comes from renewable sources.

High temperature and pressure

The indispensability of reliable level measurement technology for such processes has also been recognised by a northern German company. Here, mainly waste wood chips are converted into biomethane and fed into the gas supply network or electricity is generated by a gas-fed combustion engine. During the fermentation process, temperatures of around 1100°C and correspondingly high pressure prevail in the reformer boilers and buffer storage tanks of this biogas plant.
Not easy conditions for a measuring device from which precise results and durability are expected. Therefore the MBA800 from MBA Instruments’ proven patented rotating vane series was chosen.
"The unique shaft and vane, which have proven themselves successfully for decades in a wide variety of types of bulk solids as well as under difficult conditions such as bulk flow, withstood the heat," Frank Wengler reports with pride.
"To achieve this, it was sufficient to mount the unit at the furthest possible distance from the heat source, which ensures a certain cooling of the highly complex technology. Despite this distance, the measurement results proved to be no less precise."

MBA800 - the popular series

The MBA technologies are characterised by coordinated measuring principles and the greatest possible scope for different applications. The MBA measuring devices are used in bucket elevators, storage silos, hoppers, ship loaders and transfer stations. "Our proven rotary vane forms the basis of our individually designed measuring process," explains Frank Wengler, who is responsible for the technological development of level measurement. "This is also what - almost - everything revolves around at MBA Instruments."
What the engineers combine as drive technology for this measurement process was previously completely unknown as a component: A stepper motor is used instead of a synchronous motor. This motor has already been able to prove its reliability and freedom from wear in the automotive and even aerospace industries. "This paradigm shift not only expanded the application scope of the MBA technology through flexible application possibilities," explains Frank Wengler. "The development of the MBA800 series also took into account its use in potentially explosive atmospheres." A type examination according to ATEX finally made the safe use of the rotary vane in dust explosion areas official.

The MBA888 - the handy alternative

Being able to adjust the unit flexibly is one of the great strengths of the MBA800 series, but the setting perfectly adapted to the respective purpose can be sufficient in many cases. "Plant operators often find it appealing that they can try out different things and adjust the meter themselves again and again, and this is one of the reasons why they opt for the MBA800," the product manager knows from experience. "My tip, however, is that if the plant is not expecting any changes to the products and end products in the foreseeable future and these are uniform - as is often the case - the MBA888 device proves to be quite as effective and stable as the MBA800. It is ultimately the smaller, more compact and affordable alternative." Here, only the settings cannot be changed as flexibly, but not every operator has a particular soft spot for technical "gimmicks".

Further improvements

To stay up to date, there are regular technical revisions. The latest ones concern the software on the circuit board in the unit housing. In dry bulk material, it can happen that the important wing of the meter gets caught. If the malfunction is quickly detected correctly and a signal is triggered, immediate action can be taken to restore smooth operation. So far, this has been possible within 2 to 3 seconds. The engineers have now succeeded in halving this time again.

Everything from a single source

MBA Instruments can guarantee the high quality of its products with a clear conscience, as all devices are manufactured from A to Z at the Quickborn site near Hamburg. In this way, it is also possible to react promptly and specifically to customer requests. "The mutual exchange with the customer is the first step towards successful implementation. Our aim is to supply each customer with a measuring device that is precisely tailored to the individual application," says Frank Wengler. In addition, the right device for an individual requirement can be found with the help of an online product configurator on the MBA Instruments website. From the operating voltage to the switching behaviour to the maximum temperature and tank pressure, precise specifications help to select the right measuring technology. Further details are then clarified by e-mail and in a personal conversation. For Frank Wengler, this is a decisive criterion for a quality-conscious manufacturer. "We always design in close exchange with our customers. After all, if measuring instruments are used in applications for which they were not intended, any device modernisation will ultimately reach its limits."