Application 4
Application 4
Application No.4 - Lime Slurry Plant
Application No.4 - Lime Slurry Plant
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This application deals with the production of Lime slurry for use in water treatment.
The project involved panel design, plc and hmi application software, and on site commissioning.
Key components:- Mitsubishi Q series PLC, Beijers E1071 hmi, Mitsubishi Inverters
Please scroll down to see more detail of the application
The central part of the system is a Mitsubishi Q series plc, communicating over ethernet with:- a Beijers hmi, and the customer's SCADA system. The Inverters are controlled using analogue signals from the plc. All manual control is carried out via the touch screen.
The above drawing shows a schematic representation of the Plant.
The Lime plant is controlled via a plc based control system, with it's own operator interface (hmi), giving the operator access to all necessary functions, timer and parameter adjustment, and notification of any alarm condition. Apart from depicting the status of the machine, the hmi incorporates several different levels of password protection, enabling parameters to be accessed and modified without the need for a laptop
The manufacture of the panel, in this instance, was sub contracted due to the work load and time scale
What the plant does
Lime is blown into the silo from a road tanker. The monitoring of the silo pressure, and the control of the tanker valve is by others.
Water and lime are accurately added to two mixing tanks (on demand), which mix the lime into a slurry. This batch of slurry is then transferred to the slurry tank, which is of a much higher capacity.
The lime slurry is then pumped around a closed loop system, maintaining a set flow. A PID algorithm within the plc controls the speed of the recirculation pumps. Lime is drawn from the system as required by the process, causing the PID loop to respond accordingly.
Manual operation, timer and parameter adjustment are all available via password protected screens on the hmi.
The plant interfaces via ethernet to the main plant SCADA system
The slideshow above shows photographs of the plant that PJC Systems controlled.
Lime is offloaded from a road tanker into an internal silo. The plant mixes a lime slurry comprising a known quantity/weight of water, with a percentage of lime added and mixed for a time. Once the batch is made up, it is transferred to a holding tank. The lime is then pumped around a recirculation loop, feeding a water treatment process, on demand, to correct the pH
The slideshow above shows the hmi screens that
PJC Systems designed for this project.
PJC Systems developed pages to depict the status of all aspects of the plant, and to generate appropriate alarms
System times and parameters were made adjustable under the appropriate password level
Manual control was also via the hmi
PJC Systems produced the engineering drawings shown in the slideshow above:
Externals - showing how all the external wiring connects to the system
Internal wiring diagrams - showing all internal panel wiring.
External Layout - showing the layout of the outside of the panel, in particular the door layout.
Internal Layout - showing the arrangement of the internal components
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