Automatic rotation speed control for hammer mills with remote maintenance
Since 1959, Tietjen Verfahrenstechnik GmbH has been building hammer mills for the most diverse range of applications. Recently, the company has been using JUMO technology for dosing system control. Together with JUMO Engineering the company has also developed a modern web application to further develop the innovative Tietjen remote maintenance concept for hammer mills. The result of this fruitful partnership is a JUMO control unit optimally tailored to its application, to a design by Tietjen and with software adapted to suit the customer. The mill systems produced by the company are customer-specific, and are used predominantly in the animal feed and pet food manufacturing industries, but they are also used to crush wood and fibre or biowaste and biomass. An important component of the efficiency of each mill is the upstream dosing equipment. Plants used for biomass processing in particular usually require the input material to be dosed. Many plants require an aspiration system for dry material, i.e. a stream of air that conducts the dust produced to a separation device. Moreover, no hazardous materials such as metals, stones or plastics are to find their way into the process.
High-precision control required
Depending on the application, auger, vibration or drum feeders may be used. Their speed of rotation must be precisely monitored to ensure that the defined quantity of grist is always fed in. An added complication is that the plant reacts differently depending on the grist, and the control parameters must be precisely set. Starting up a plant of this kind is also difficult, since it can take a while until a continuous flow of grist is being fed in, depending on the type and composition of the feed used. During this period the control system must remain stable, since overdosing results in plant shutdown.
Last year, Tietjen Verfahrenstechnik GmbH searched for a new, modern “Industry 4.0” control unit component to perform these tasks, in particular one offering functions such as remote maintenance. Its main task is to control the rotation speed of the electric drive, which regulates the dosing depending on the load placed on the grinding mill. What was needed here was a constant PD controller that was as precise as possible and a 24-volt power supply. The control device had to have UL approval for export purposes, and in addition it should be possible to install it in a control cabinet. Furthermore, it must be possible to issue a regulator release and set a target values externally via an superordinate controller. Optional activation of other temperatures for plant monitoring purposes are also envisaged. JUMO had a product that matched all these requirements in its portfolio: The JUMO DICON touch is a multichannel process and programme controller based on a modular hardware architecture that can be used in a wide range of applications.
In addition, the JIMO DICON touch offers useful functions for this particular use case, such as time-independent parameter set switching or, alternatively, a warm-up ramp. Moreover, it is possible to define threshold values that trigger a shutdown of the controller and therefore also shutdown the feeder system in the event of a mill overload.
Modern remote maintenance concept
To make the hammer mills compatible with remote maintenance, and enable maximum simplicity of operation and commissioning by on-site servicing staff by from the Tietjen Verfahrenstechnik servicing department, all JUMO DICON touch and TCU 96 (customer name for the OEM device) devices are delivered with a specially developed web application.
Tietjen Verfahrenstechnik and JUMO Engineering are together putting the wide-ranging demands of the ‘Industry 4.0’ revolution into practice. The result has been implemented as standard on the device-side web server. This can be accessed via a variety of routes: via a local Wi-Fi network using a laptop, tablet or smartphone, via a VPN gateway or via the end user’s network infrastructure over DSL. The application is configured to allow just the operation of the plant or to also allow remote commissioning and optimisation. The corresponding configuration parameters for these modes therefore only accessible through a password-protected portal and in a separate configuration environment. In operation, the controller can be operated without password protection. With this web application, Tietjen Verfahrenstechnik GmbH is able to easily model their sophisticated remote maintenance concept in its entirety.