Dependable fill-level control in coal mining

Dependable fill-level control in coal mining

Mine workings and opencast pits are well known for their harsh working conditions. This applies equally to the technology deployed. For this reason, durable and reliable measuring instruments are required to monitor groundwater.

Ten percent of worldwide coal deposits are to be found in Australia. As the leading coal exporter, coal mining is one of the most important economic factors on that continent. Mining of the raw material, however, is not without its pitfalls. The operator of an Australian opencast approached STS as they were seeking a pressure transmitter for fill-level monitoring at depths of up to 400 meters.

Mining operations have a heavy influence upon groundwater. The aquifers surrounding the coal mine become drained, which leads to a sinking of the depression cone. This sinking alters the natural hydrological conditions underground by creating paths of lowered resistance. What this then leads to is water penetrating the open pit and underground workings. As a result, the constantly inflowing water needs to be continuously pumped out of the pit to ensure a smooth and safe extraction of the raw material.

To control the groundwater level and the pumps used for drainage, the operators of the opencast needed a pressure transmitter to monitor the fill-level according to their requirements. Stipulated was a pressure range from 0 to 40 bar (400 mH2O) ambient pressure, as well as a cable length of 400 meters. The solution offered by STS at that time, the ATM.ECO/N/EX, read only to 25 bar and had a cable length of 250 meters.

But since STS is specialized in customer-specific pressure measurement solutions, this challenge was to prove no major obstacle. In short time, the failsafe ATM.1ST/N/Ex pressure transmitter for fill-level was developed, which precisely meets the pressure requirements and is equipped with a 400-meter-long Teflon® cable. It is also convincing in its accuracy of just 0.1%. STS decided upon development of the new pressure transmitter for a Teflon® cable, a sealed cable gland and an open aeration tube (PUR is too soft for this). In addition, there is also a screw-on ballast weight to ensure a straight and stable measuring position. The stainless steel strain relief, which can also be screwed on, helps to relieve strain on the electrical cable. As the device designation indicates, it also carries the EX certification for use in explosive areas.

ATM.1ST/N/Ex with strain relief (left) and ballast weight (right), each screw-on.

Being an expert in customer-specific pressure transmitters, STS was able to supply the ATM.1ST/N/Ex in less than three weeks.

The features of the ATM.1ST/N/Ex in brief:

  • Pressure range: 1…250 mH2O
  • Accuracy: ≤ ± 0.1 / 0.05 % FS
  • Total error: ≤ ± 0.30 %FS (-5 … 50°C)
  • Operating temperature: -5…80 °C
  • Media temperature: -5…80 °C
  • Output signal: 4…20 mA
  • Materials: Stainless steel, titanium
  • Electronic compensation
  • Common process connections available
Applications of pressure measurement technology in the marine industry

Applications of pressure measurement technology in the marine industry

Sensor technology plays an essential role in the maritime sector and most particularly in shipbuilding. The dependable and accurate measurement of pressure, temperature and other variables within various tanks is an important measure in preventing the escape of aggressive fluids, controlling water circulation systems in ship operations and also in guaranteeing a smooth transportation of cargo across the high seas. 

The sensor technology employed here has to meet numerous stringent requirements. These include, above all, that the materials utilized are robust enough for use over the longer term. The electronics must also be capable of withstanding the harsh conditions of the open seas and therefore remain highly durable.

Monitoring of dry and liquid cargoes

The main component of freight consists of wares to be shipped, with both dry and liquid cargoes being transported by sea. Dry cargo is the term we use when bulk goods such as grain and animal feed, as well as piece goods usually held in containers, are being transported. Liquid cargoes, however, require particularly careful and reliable monitoring, since highly sensitive substances, including gasoline, oil and gas oil, are usually being transported here. The products employed must be particularly robust and reliable in order to prevent the escape of aggressive liquid substances and thus prevent accidents of the gravest ecological consequences. This means that sensory systems must also meet the very highest of demands.

Freshwater and wastewater tanks

On cargo ships, fresh or drinking water is either carried in special potable water tanks or obtained from seawater through a purification treatment. The collection, treatment and disposal of ship wastewater in internal storage systems must also be monitored using an appropriate technology. Since this wastewater is often contaminated with harmful substances, such as oils or cleaning agents, its processing also remains subject to certain additional requirements. Both freshwater and wastewater tank systems are checked and monitored using built-in sensors. In this way, the systems can be monitored most efficiently, which in turn guarantees an optimum water supply across the high seas.

Ballast tanks

Ballast tanks are an important part of shipping. Without loading these tanks, large cargo ships can sometimes be too light, meaning that their propellers will not sit deep enough in the water. To ensure a sufficient draught, the ballast tanks are filled up with seawater and can even be used to even out the weight distribution across a loaded ship. Since these tanks are being filled with saltwater, both the materials of the tanks and those of the sensors used must be robust and corrosion-resistant. Special attention is also paid to high reliability and durability, since the sensors are virtually inaccessible underway during on-board operation and must therefore function perfectly without any manual maintenance or inspection.

Image 1: Level measurement installation options

Special sensory requirements

Over the last few years, the shipbuilding industry has seen a steady stream of decisive innovations to which the production of sensors employed must respond accordingly. Whereas 15 years ago, for example, the durability of stainless steel was still a major concern, today we recognize that it corrodes when it comes into contact with saltwater at temperatures above 21 degrees Celsius. Nowadays, titanium is employed instead. STS recognized this problem early on and was one of the first companies to use titanium as a permanent component of its sensing technology. This extremely stable and robust material is now used as standard for a wide range of pressure transmitters and immersion probes, since it can withstand even the most adverse of conditions.

The technological requirements are constantly changing as the industry itself grows and evolves. What was considered standard a short time ago may already be inadequate by today. STS is therefore constantly striving to further develop the sensing technology it offers, thus guaranteeing reliability and accuracy, even in the face of increasing industrial demands. This flexibility and quality does pay off, however, with return rates negligibly low and problems more likely to arise from human error than through faulty technology.

Collaboration with AE Sensors

For over 27 years now, STS has been working together with the Dutch family-run company AE Sensors. Together, we supply major customers in the shipbuilding industry with their sensing technology. With competent consulting and the use of flexible solutions, our customers have been able to record enormous growth in just a short period of time. By now, state-of-the-art vessels are being built at shipyards all over the world, in which submersible probes, pressure transmitters and other tailor-made solutions from STS are being used. Above all, our ATM/N and ATM.1ST/N sensors made of titanium and fitted with Teflon cables are being deployed as standard.

Thanks to their modular mounting system, installation of our sensors can be variably adapted to the prevailing requirements. Various forms of measurement, such as positive or absolute pressure, may also be implemented. The high flexibility of STS and our partner AE Sensors, combined with the flawless quality of our sensing technology, has proven itself over many years of cooperation with our satisfied customers.

The turbocharger succumbs to the pressures of energy conservation

The turbocharger succumbs to the pressures of energy conservation

For many years turbochargers were only found on expensive sports cars and diesel powered engines, but emissions regulations changed the way the world viewed forced induction. Although at the core was still the quest to improve performance, now manufacturers were looking at restoring performance and driveability to downsized fuel-sippingengines. So in the 21stCentury, almost everything from the little 999 cm3 Ford Ecoboost to the latest Ferrari’s all gained shiny new turbo technology.

But almost as soon as the tech came into its own it seems set to become redundant, upstaged by the new eCharger. Already Audi’s fitted this to the series production SQ7 and will be rolling out the technology to future production vehicles as 48 Volt electrification gains traction.

The key advantage to the electrically driven supercharger is that, as with turbochargers, there are no parasitic losses; but unlike most turbo’s there’s no turbo lag either and no need for a wastegate. The powerful electric motor can spool up the impeller to 70,000 rpm in less than a second, which eliminates turbo lag.

This naturally improves driveability and reduces consumption and emissions by between 7 and 20 percent when the device is used on a vehicle equipped with regenerative braking, which captures the car’s kinetic energy and turns it into electricity.

Pressure is key to unlocking the eCharger’s performance

Electronically controlled, the eCharger can be mapped to optimize engine performance while maximizing the energy recovered from the exhaust gas, but in order to achieve this Utopia, engineers need to create a map of the boost the engine requires by measuring manifold pressures at various engine loads and speeds. This can only be done with the aid of top quality pressure sensors.

As with any super/ turbo-charger, it’s important that the unit is matched to the engine’s requirements: Failing to do this, will either starve the engine or result in unnecessary electrical power consumption.

Being a maturing technology, not much research and testing data is available to engineers wishing to explore the boundaries of eCharge superchargers. Although fluid dynamics and electrical engineering can provide good foundations from which to build, it’s still vital that theories are validated under real-world test conditions.

In order to qualify the performance, once the baseline eCharger has been selected, the vehicle is equipped with extremely accurate pressure sensors that are readily calibrated and provide precise readings over a wide range of manifold boost pressures and temperatures. These sensors must also be resistant to vibration and chemical degradation.

Both on the engine dynamometer as well as road testing, throttle position/ engine speed/ Manifold air Pressure and temperatures are continuously recorded to ascertain the interrelationship of these key inputs.

From this information, engineers are able to verify that the correct eCharger configuration has been selected whilst at the same time ensuring that the closed loop engine management controls are able to correctly respond to the key variables.

The result of getting this right delivers a vehicle, such as the SQ7, which has stunning performance, drive ability and fuel consumption whilst still meeting future global emissions regulations.

Research project DeichSCHUTZ: Reliable measurements for safer waterfronts

Research project DeichSCHUTZ: Reliable measurements for safer waterfronts

In extreme flood situations, the hopes of those people affected lie solely with the dykes – will they hold or not? A dyke failure like the 2013 flood in Fischbeck (Saxony-Anhalt) caused immense damage to inland areas, which continue to have an impact to this day. The active research project DeichSCHUTZ (dyke protection) at the Bremen University of Applied Sciences is involved in an innovative dyke protection system that could prevent failures of this kind.

In Germany alone, river dykes safeguard many thousands of kilometers of waterfront lands. From today’s technological perspective, dykes consisting of three zones are being constructed. The individual zones, viewed from the water-side to the land-side, are built with steadily increasing porosity, thus affording good drainage of the dyke body during a flood event. In Germany, however, many older dykes of homogenous construction do still exist, such as the dyke breached during a flood of the River Elbe in June 2013 in Fischbeck. In contrast to the 3-zone dykes, older ones are particularly vulnerable to prolonged flood conditions. Water seeps into the dyke itself and its saturation line rises further within the dyke body over extended periods of high water. The further this saturation line rises, the more the ground material is subjected to buoyancy. The dyke thus loses its own essential self-mass, required to counteract against the pressure of high water.

Stabilization of a breach-prone dyke requires enormous resources in material and personnel, as well as time, which in acute flood situations is a scarce commodity.  Backup procedures are thus required, which, in terms of personnel, materials and time commitment, are more effective than layering sandbags on the landward side of the dyke.

Innovative mobile dyke protection system

Christopher Massolle of the Institute for Hydraulic and Coastal Engineering at the Bremen University of Applied Sciences is developing a solution that can considerably reduce the input of time and personnel. With the DeichSCHUTZ research project, sponsored by the Federal Ministry for Education and Research, an innovative, mobile dyke protection system is being tested for stabilizing dykes during flooding events. Measurement technology supplied by STS is also playing a role here.

To assess the mobile dyke protection system, a test-dyke has been built on the premises of the Agency for Technical Relief in Hoya. To this end, a U-shaped retention basin holding some 550 cubic meters of water has been constructed, at whose end sits a dyke.

As can be seen in the video, numerous pipes have been deployed at the left side of the dyke. Within these pipes rest ATM/N Level Sensors produced by STS. In the test arrangement, the retention basin is filled with groundwater. Under conditions approaching reality, the water should rise to a level of 3 meters over a period of 30 hours. The submersible level sensor ATM/N  now measure development of the saturation line over this time. With a pressure range from 1 to 250 mH2O and an accuracy of ≤ ± 0.30 %FS (-5 to 50 °C), this is recorded down to the very last centimeter. When the saturation line no longer continues to rise, the mobile dyke protection system is introduced to the water-side slope and should prevent the further penetration of seepage water. The dyke body now continues to drain and the extent of the resulting shift in the saturation line is to be measured by the level sensors employed. It is from these measured results that the functionality of the protection system can lastly be assessed.

Using geomorphometry for hydro-geomorphological analysis in a Mediterranean research catchment

Using geomorphometry for hydro-geomorphological analysis in a Mediterranean research catchment

Abstract

The aim of the paper is to apply an object-based geomorphometric procedure to define the runoff contribution areas and support a hydro-geomorphological analysis on a 3-km2 Mediterranean research catchment (southern Italy).

Daily and subhourly discharge and electrical conductivity data were collected and recorded based on three-year monitoring activity. Hydro10 chemograph analyses on these data revealed a strong seasonal hydrological response in the catchment that were different from the stormflow events that occurred in the wet period and in dry periods. This analysis enabled us to define the hydrochemograph signatures related to increasing flood magnitude, which progressively involves various runoff components (base flow, subsurface flow and surficial flow) and an increasing contributing area to discharge. Field surveys and water table/discharge measurements carried out during a selected storm event enabled us to identify and map specific runoff source 15 areas with homogeneous geomorphological units previously defined as hydro-geomorpho-types (spring points, diffuse seepage along the main channel, seepage along the riparian corridors, diffuse outflow from hillslope taluses and concentrate sapping from colluvial hollows). Following the procedures previously proposed and used by authors for object-based geomorphological mapping, a hydro-geomorphologically-oriented segmentation and classification was performed with an e-Cognition (Trimble, Inc) package. The best agreement with the expert-based geomorphological mapping was obtained with weighted profile and 20 plane curvature sum at different-size windows. Combining the hydro-chemical analysis and object-based hydro-geomorphotype map, the variability of the contribution areas was graphically modelled for the selected event which occurred during the wet season by using the log values of flow accumulation that better fit the contribution areas. The results enabled us to identify the runoff component on hydro-chemograph for each time step and to calculate a specific discharge contribution from each hydro-geomorpho-type. This kind of approach could be useful applied to similar, rainfall-dominated, forested and no-karst 25 catchments in the Mediterranean eco-region.

Read the whole research study.

Source: Domenico Guida1, Albina Cuomo (1), Vincenzo Palmieri (2)
(1) Department of Civil Engineering, University of Salerno, Fisciano, 84084, Italy
(2) ARCADIS, Agency for Soil Defense of the Campania Region, 5 Naples, Italy