13-06-2012, 04:48 PM
Cement Plant Process Automation
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Many recently built or renovated medium and large-scale cement product lines have adopted Distributed Control Systems (DCS). Unfortunately, many of the smaller plants aren’t up to speed technologically, rather depending heavily on traditional instrumentation. Some such plants monitor and control the process manually.
The cost of large-scale DCS systems is so high that these firms can’t afford it. In order to solve these problems we have developed a new DCS system that is lower in cost and have implemented it in our plant.
The field environment in our plant is high in temperature, with extensive dust and serious electromagnetic interference (EMI) produced by many transducers, and the technical measurement points are very spread out, which increases wiring costs and workload. After investigating and selecting products from different manufactures with the best price/performance ratios, we chose the I-7000 series remote data acquisition modules
I-7000 series remote data acquisition modules: With these products, you can use the serial port on your laptop or desktop PC to connect to voltage inputs, thermocouples, strain gauges, rtds or any analog or digital sensors
The I-7000 Modules have low power consumption and require 10 ƒ? 30 VDC. They come with free DCON Utility configuration software for setting them up and they also come with Free EZ Data Logger software for PC based data logging. The I-7000 modules are perfect for small or large systems.
Subsystem Architecture
As shown in figure2, the vertical kiln subsystem has three levels, which are the workshop management level, the workshop control room and the workshop field level. The connection among the three levels was facilitated through the RS-485 and technical arguments in vertical kiln are acquired by modules including the I-7018, I-7033, I-7050, I-7021, I-7041 etc.
The automation controller used in the formation of a ball of raw cement comprises embedded control module I-7188, TOUCH 200 human machine interface (HMI), Data I/O modules (such as the I-7016, I-7080, I-7021), strain
In the central control room we usee the I-7188 with multiple serial ports as a data buffer between IPC and field levels. In this way 2 to 3 IPCs can work at the same time and all of them can control or adjust the arguments in the system
The IPC in the workshop control room is mainly used for computing, displaying, auto-analyzing, storing and controlling the data in the system.
The IPC at the workshop management level performs computing, displaying, analyzing and storing of data and works out the control standards for each technical argument based on the evaluation requirement which, in turn, is regarded as the main criteria.
System Software
Because of the complexity of the system requirements, which include friendly HMI and real-time monitoring and control, we develop the control software for IPC in Visual Basic 5.0 for Windows. The software is composed of a system management module, a simulation display module of process flow diagraming, a simulation display module of the instrument screen, database management module, data communication module, control algorithm module,etc. The use of many ActiveX controls in the software greatly reduces development time.
Introduction
Automatic Streetlight needs no manual operation for switching ON and OFF when there is need of light. It detects itself weather there is need for light or not. When darkness rises to a certain value then automatically streetlight is switched ON and when there is other source of light i.e. day time, the street light gets OFF. The sensitiveness of the street light canal so be adjusted. In our project we have used four L.E.D for indication of bulb but for high power switching one can connect Relay (electromagnetic switch) at the output of pin 1 of I.C LM358 Then it will be possible to turn ON/OFF any electrical appliances connected all the way through relay.
PRINCIPLE:
1) This circuit uses a popular timer I.C LM 358. I.C LM358 is connected as comparator with pin-6 connected with positive rail, the output goes high(1) when the trigger pin 3 is at lower then voltage level at pin no 2. Conversely the output goes low (0) when it is above pin no 2 level. So small change in the voltage of pin-2 is enough to change the level of output (pin-1) from 1 to 0 and 0 to 1. The output has only two states high and low and can not remain in any intermediate stage. It is powered by a 12V power supply. The circuit is economic in power consumption. Pin 4 is ground and pin 8 is connected to the positive supply and pin 1 is grounded. To detect the present of an object we have used LDR and a source of light. LDR is a special type of resistance whose value depends on the brightness of the light, which is falling on it. It has resistance of about 1 mega ohm when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It responds to a large part of light spectrum. We have made a potential divider circuit with LDR and 10K variable resistance connected in series. We know that voltage is directly proportional to conductance so low voltage we will get from this divider when LDR is getting light and high voltage in darkness. This divided voltage is given to pin 2 of IC LM358. Variable resistance is so adjusted that it crosses potential of 1/2 in darkness and fall below 1/2 in light. Sensitiveness can be adjusted by this variable resistance. As soon as LDR gets light the voltage of pin 2 drops of the supply voltage and pin 3 gets high and LED or buzzer which is connected to the output gets activated