The vacuum pan is a single-effect evaporator. It can be rightly called an evaporator crystallizer since evaporation as well as crystallization is taking place in pans.
The following are the three main functions are carried out in vacuum pans.
The batch pan automation advantages are as follows.
Massecuite boiling in batch pan bodies are very critical operation as the supersaturation of juice boiling inside the pan body must be maintained in a very narrow range.
Conscientious of the pan operator will lead to dissolving the false grain due to the increased number of water strikes in the pan body.
This results in an increased number of steam and vapor requirements. Now a day or in the present situation energy conservation such type of carelessness is inexpensive.
In this situation for conservation energy, it has become inevitable to implement the automation systems for the batch pan for feed control to maintain the massecuite boiling inside the batch pan at a supersaturation or metastable zone.
The conductivity or brix of massecuite and level of massecuite inside the batch pan are continuously monitored for automatic control of feed liquor to the batch pan body.
The exhaust steam pressure inside the calendria of the pan body is continuously monitored and the flow of steam to the batch pan is regulated.
And the remaining operations such as selection of feed liquor, seed slurry feeding control of vacuum braking, pan washing, closing, and opening of the discharge valve can also be automated.
This system consists of two separate control loops for brix and the temperature control of the molasses.
For effective boiling of massecuite in the pan body, these control systems are always better to maintain the brix and temperature of the molasses.
Depending upon the specific relation between the viscosity sensor signal and brix. The 4 to 20mA DC signal is obtained through the calibrated brix transmitter.
The conductivity or viscosity sensor detects the brix values of the molasses for control of the brix.
The brix transmitter sends the measured value to the controller and the controller compares the received signal called the measured value with the given setpoint. And the difference between these two signals operates the proportional control valve to control the flow of water to maintain the desired brix.
Similarly, the temperature sensor RTD senses the temperature of the massecuite inside the body. The output signal of RTD is converted into 4-20mA DC through the temperature transmitter and this signal is sent to the controller.
The controller compares the measured value with the given set point. The difference between these two signals in terms of 4-20mA DC operates the temperature control valve and regulates the steam entering into the molasses conditioner to maintain the temperature of the massecuite.
This system is used to control the pH of the final juice and shock lime.
Here the pH of the final juice is maintained at pH 7.0 and the pH of shock lime is maintained between 8.5 to 10.5.
This process is carried out in the juice Sulphitation tank with respect to the flow of mixed juice.
The pH electrode is used to sense the pH of shock lime,
The pH transmitter sends the signal to the controller
The controller commands the control valve through VFD to control the flow of Milk of Lime to control the pH of shock lime to its desired value
Similarly for the final juice
The pH electrode senses the pH of the final juice,
The transmitter sends the pH signal to the controller to control the flow of molten Sulphur through VFD or secondary airflow for controlling the pH of the final juice to the desired value.
Generally, the variation of pH in the above system using single loop operation has been seen in most the sugar industries.
In such systems, the pH of the final juice is measured and the flow of Milk of Lime is controlled with manual adjustment of Sulphur dioxide gas.
It is desirable to have an inline pH electrode with a washing system.
The measurement of the pH of sampled juice is to ensure uninterrupted signal availability for the control system. However, the cost issues trammel the installation of such automated systems.
The following are the benefits of pH automation.
Before the startup of the pan, the following valves must be closed.
PLC ladder logic design to control 3 motors with toggle switch and explain the program…
VFD simulator download: Master the online tool from the Yaskawa V1000 & programming software for…
The conveyor sorting machine is widely used in the packing industries using the PLC program…
Learn the example of flip-flop PLC program for lamps application using the ladder logic to…
In this article, you will learn the STAR DELTA programming using PLC controller to start…
Lube oil consoles of rotary equipment packages in industrial process plants are usually equipped with…