Instrumentation manufacturer and supplier Allpronix has introduced the APM 3DLevelScanner into South Africa, after several hundred units have already been installed for a wide range of applications in European markets.
This new family of level-detection devices employs an array of low frequency transducers to measure and map an entire surface area. It uses a patented algorithm that processes the input information to generate a three dimensional (3-D) map of a load. The APM 3DLevelScanner can measure the level, volume and mass of materials and ore with accuracy, in many applications that other technologies cannot reach.
It measures practically any kind of material stored in an almost unlimited variety of containers, including large open bins, bulk solid storage rooms, stockyards and warehouses. It can map the precise shape of loads that randomly take shape over time inside silos and on ore stockpiles, and can do the same in many other virtually inaccessible locations.
The APM unit provides much greater accuracy than with regular instrumentation in terms of its measurements and significantly enhanced overall performance, reliability, durability, ease and speed of installation, and operating convenience. This translates into significant cost savings and faster returns on investment, and allows managers to make informed decisions that go right to the bottom line throughout the entire supply chain.
Until the advent of such 3-D mapping technology, four significant technological approaches have been employed widely in industry to measure the continuously fluxing levels of solid materials inside silos and other storage containers. Three of these methods are through the use of electromechanical (yo-yo) level sensors, ultrasonic level sensors, and radar level sensors, which all measure the height of the heaped materials at one point only. However, material has more than likely piled up unevenly, and thus these measurement techniques do not provide sufficiently accurate measurements of the average level and volume of contents.
The fourth approach, through the use of load cells, subtracts the weight of an empty container from a partially filled one, arriving at the weight of stored solids and liquids, with a high degree of accuracy. The container is mounted on top of the load cells, which are calibrated to measure the tank level. While fairly accurate, this method is expensive, as the load cells must be built-in and installed underneath the silo or container. On the other hand, it is not possible to apply this method to silos that are not standing on metallic legs, such as concrete silos.
The APM 3DLevelScanner, however, employs a two-dimensional (2-D) array beam-former to send low-frequency pulses and receive echoes of the pulses from the contents of the silo, bin or other container. The device's digital signal processor then samples and analyses the received signals. From the estimated times of signal arrival and the directions of the received echoes, the processor generates a 3-D image of the surface that can be displayed on a remote screen.
The large beam angles inherent in low-frequency signals cause traditional ultrasonic instruments to receive echoes from the contents below the beam as well as from the silo walls. Such sensors with a single antenna cannot differentiate between the echoes coming from the contents and those coming from the container walls.
To avoid this serious problem, they work at high frequencies, which by definition have a narrow beam angle that never hits the walls of the silos, but cannot penetrate and work in dusty conditions, therefore also yielding inaccurate measurements.
APM's technology actually takes advantage of the large 70° beam angle that results from working at a very low frequency, by using a three-antennae system with proprietary algorithms to add another important dimension, direction. The result is that every 10 seconds to 15 seconds the 3DLevelScanner receives a matrix of x-y-z position coordinates that represent the echoes from the surface of the contents in the silo. Connecting these points together generates a highly accurate profile of the surface area, which in turn yields more precise measurement of the amount of materials being stored.
While traditional sensors with a single transducer are capable of measuring only a single point on the contents' surface, APM's technology implements a circular array of three transducers for beam forming both at reception and transmission. The sensor estimates the echoes' time delay and spatial direction through the use of direction of arrival algorithms. By derivation from the geometrical structure of the bin, which is to be entered by the user, all echoes from the contents' surface are considered, while those from the silo walls are discarded.
Conditions inside bins and silos are often harsh. They are dusty, suffer extreme
temperatures, and are subject to anomalies of irregular surfaces and unbalanced filling and emptying.
The APM 3DLevelScanner is unaffected by the conditions associated with the type of materials being stored, avoiding the need for special calibration. It is unaffected by conditions like dust, filling noise, humidity, or temperature.
The APM unit is robust, technologically advanced, accurate, versatile and a solution to many industries' measurement limitations. It is capable of handling different kinds of silos and materials, and it has a competitive price that can justify its installation costs when compared with its value.
Large-scale productions in varied industries, ranging from mining and cement and plastics production, to food and beverages and chemicals processing, need to overcome challenges of accurately assessing and controlling inventory in order to successfully manage the entire production process.