Reaction tank

The plant display reaction tank (<proj_path>/panels/mainpanels/reactor.pnl) shows a chemical reaction tank with a heat exchanger to guarantee ideal reaction conditions and thermal stabilization. Open the plant display via the geographical overview or directly via the direct selection button in the operating block.

The tank R01 is filled with the primary medium via the feeding pump P1 and a control valve. The metering valve V4 registers small amounts of reaction supporting substances. The system P1 - R01- V1 is a continuous process. The agitator M1 ensures thorough mixing of the primary medium and the reactants and takes care of the thermal balance in the tank's content.

The heat exchanger is operated by the controlled inflow of the heating and cooling mediums. The valve V2 regulates the heating medium inflow and V3 determines the inflow of the cooling medium. The mediums are mixed in the heat exchanger which produces a resulting heat exchanger temperature. This temperature influences the reaction tank. The return takes place unregulated, except for a shut-off valve that is not integrated in the automation process.

Procedural boundary conditions dictate that the amount of medium in the reaction tank never falls below a defined minimum level. There is also a maximum filling level. The filling level includes a reserve for expansion of the reacting medium.

The level in the tank is monitored permanently and controlled via the inflow. In addition, there are minimum and maximum alarms for the tank level.

The outflow volume depends on the downstream process and is discontinuous. In the control loop, this is seen as a disturbance.

The reaction tank can be used flexibly for endothermic and for exothermic reactions, as well as for necessary exterior stabilization. The temperature of the reactor content is monitored permanently and is assumed to be almost uniform throughout the medium on account of the agitator M1. The temperature is guaranteed by setpoints controlling the flow valves for the inflow of heating and cooling mediums (V2, V3). The temperature control has a direct influence on the valve V2. The inverse output when controlling V3 is however enforced (for example, V2 = 80 % open then V3 = 20% open).

Simulation

The simulation of the reaction tank is implemented in a Control manager (-f pid_scripts.lst). In the pid_scripts.lst, a script runs for the tank model and another for the reactions of the devices. The regulation is realized in the PID manager (WCCOApid.exe).

In the following figure, the simulation is started by selecting the option button in the left bottom corner:

Figure: Simulation Settings

Note:

The managers have to be started for the operation of the reaction tank and the following entries must be made in the WinCC OA console:

 WCCOActrl –num x –f sim.lst

The regulation is executed via the manager (WCCOAPID.exe):

 WCCOAPID -num x

These work at the moment only when you have installed the extension<version>. For details on installing demo extensions, see the chapter properties panel.

On: Starts the simulation. ThetankR01 is filled with the primary medium via the feeding pump P1 and the control valve. Theagitator M1takes care of mixing the primary medium with the reactants and ensures the thermal balance in the tank content. The mediums are mixed in the heat exchanger producing a resulting heat exchanger temperature. This temperature influences the reaction tank.

Off : Stops the simulation.

Loop time : Define the loop time in milliseconds.

Max. change rate of value per cycle : Defines how much, at the most, the value may change within a cycle.

Figure: Plant Display, Reaction Tank

The Reglec symbol next to the level and temperature displays opens the following detailed indicator.

Figure: TICA02

This indicator displays the actual measured value, defines setpoints directly in the text field or with the slider and adjust the output. In addition, the errors are shown as a percentage.

With this button you activate or deactivate the regulation. If you deactivate the regulation, manual operation is activated. When manual operation is activated, you can adjust the output manually.

Shows or hides the drag pointers.

Opens the window shown below. In this window, you can set the controller parameter and see a trend view. Different controller settings were created and saved for the PID controller. The controller settings are LICA configurations. These show the functionality of the controlled system and the influence of the different controller parameters on the control system's behavior.