Automation of the lime kiln loading process

Control system (CS) for automatic loading of a lime kiln

Our company’s specialists have developed and implemented a control system to provide automatic and manual control of actuators that load the lime kiln, as well as control of lime production parameters.

The furnace loading control system equipment (electronic equipment) is mounted in an electrical installation cabinet with a degree of protection IP54. The front panel of the cabinet contains manual controls and light signaling. The cabinet is installed near the weigh hopper (lower position of the skip hoist).

To operate the lime kiln loading control system and monitor its operating parameters, position sensors, temperature sensors and vacuum sensors were installed.

Algorithm for the operation of the lime kiln loading control system in automatic mode:

1.      After turning on the equipment, the skip hoist rises up (the control system gives the command “skip up”) and, if there is material in it, is unloaded.

2.      When approaching the intermediate hopper of the furnace, the skip lift opens the lid of this hopper using special brackets. The cover of the intermediate hopper is equipped with two closing sensors (main and backup, position 1 in Fig. 1). After receiving a signal from the sensors about opening the cover of the intermediate hopper, a time interval is counted (determined during setup) and a signal is sent to turn off the skip hoist.

3.      After stopping the skip in the upper position, the skip unloading time is counted (set during setup, approximately 2 seconds) and after this time the “skip down” command is given.

4.      After closing the cover of the intermediate hopper, a command is given to open the furnace loading hatch. The position of the loading hatch is controlled using position sensors pos. 2 and 3 (see Fig. 1).

5.      When the skip hoist reaches the lower position sensor (position 14 in Fig. 2), the “skip down” command is turned off and the skip stops.

6.      After the skip stops, the process of loading the weigh hopper starts in the lower position. The weight hopper is installed on four weight sensors (positions 18-21 in Fig. 1). Its bottom is equipped with an opening sensor and a closing sensor (items 16 and 17 in Fig. 1). The control system checks the closing of the bottom (gives a command to close) of the weighing hopper, and if it is closed, the material feeder is turned on. The weight of the material in the weighing hopper is continuously analyzed by the dosing controller, and when the set dose is reached, the feeder is switched off. Material consumption and the number of loading cycles are not recorded.

7.      After the dose of material has been collected, a command is given to open the bottom of the weighing hopper. After the bottom is completely opened (controlled by an opening sensor), the time for unloading the weigh hopper into the skip is counted and a command to close the bottom is given.

8.      After the skip is loaded, the control system waits for a command to be received from the material level sensor in the furnace.

9.      When a signal is received from the level sensor, the “skip up” command is given, after which the skip begins to move upward.

10.     Then the cycle is repeated from step 1.