Complex automation Automatic control system of lime-gas division
The system is divided into the following subsystems conventionally:
- Control of a background and batch load into the heater.
- Control of the heater unloading and of lime milk producing.
- Control of gas set.
The system independently conforms to the plant performance and modifies main tasks.
All moving mechanisms (such as carriers, a basket of stone screening, bunker rotate machine, driving actuator of valve raise, mechanisms of tensioning are provided with sensors of moving or sensors of position rating the equipment condition. These sensors are included in the control and signaling system.
It should be pointed that heaters loading set can be provided with video surveillance system with informational outputting to the Central control unit of plant adjustment, it is also has an automatic chambers changeover depending on technological situation. Two boards are used for informational presentation about quantity of fuel and stone in bunkers. On these boards during the heater working there is time residual till bunkers emptying according to plant current performance (hour, min.), and during bunkers loading there is their level is shown (%). It allows to load bunkers rhythmically and not to presume their emptying.
The control system provides quantity accounting of loaded skips into the heater and total value of weighed fuel and batch in kilograms ( per an hour, for the last hour, per a tour, for the last tour, per a day-and-night, for the last day-and-night, per a company). These data are necessary for operational analysis of the set working fro the point of view of specification and economy figures. They are ready for their rendering into automatic control system for automatic operational accounting.
The control system provides maintenance of:
- rarefication and temperature at the heater output terminal,
- control of water level in gas receiver,
- required water consumption for gas pumps.
Gas rarefication in automatic mode is provided by:
- Definition of plant capacity of loaded batch skips quantity.
- Setting of specified rarefication of loaded batch skips quantity.
- If gas temperature in heater output terminal increases the specified one the clapper of rarefication starts keeping this temperature in specified limits.
- If gas pressure after gas pump falls down lower specified limit the clapper of rarefication starts keeping the required pressure at saturation.
Just such controller allows providing work of this set in automatic mode.
Unloading of the heater is realized with the help of devices of different modifications which are operated by a frequency driving actuator or by a pulse-duration controller. The operational frequency of a driving actuator of unloading machine changes depending on lime consumption, an indirect measure of which is the level in a raw milk mixer. Water for slaking is fed discretely simultaneously with lime feeding into the lime slaking apparatus.
There is an operational set on the basis of PC computer in the Central dispatching desk (CDD) which allows holding a monitoring of the technological process.
