Distillation Column Controllability Analysis through Heat Pump Integration

According to the above variables, when the system approximation linearity and the process gain matrix are shown in the table in each case and the temperature is used as an operational variable instead of a thermal variable, the temperature is already controlled by the existing control loop , It is used for manual control. Or it will be sent automatically as the set value. This changes the system configuration, but it is done only by heat input. Therefore, Table 3 shows that the corresponding open loop gains of the two systems are different even when analyzing other input variables.

Heat pump technology can be used to thermally integrate the internal heat of the separate fractionator and stripper. This structure is a thermally integrated distillation column (HIDiC). Initially only a portion of the stripping and rectification section was integrated under the name of the SRV scheme, but the later tower design added thermal integration throughout the rectification and stripping section (Jana, Figure 6 shows a typical Partial energy integrated distillation scheme is shown.

Heat pumps are mainly used as a means to improve the thermal efficiency of a single distillation column. After the oil crisis of 1973, a heat pump auxiliary distillation tower or steam recompression tower (VRC) was used as an energy saving process in the chemical industry (Jana, 2009). In this system, the overhead vapor is pressurized by the compressor until it can condense at high temperature, which will provide the necessary heat for the reboiler. From the figure you can see a schematic diagram of this situation.

In a conventional distillation column (FIG. 1) having a feed, overhead product and bottom, heat is applied to the bottom of the stripping section. In distillation, heat is used as a separating agent. Heat is typically supplied to the bottom reboiler to evaporate the liquid mixture, but heat is lost when the top steam is liquefied in the reflux condenser. The temperature of this heat corresponds to the highest temperature point in the distillation column. The temperature of the heat released at the top of the rectifying section corresponds to the lowest temperature point in the distillation column. Therefore, the distillation involves heat loss from high to low temperature due to the separation operation. If the heat released in the rectification section of the distillation column is not recycled, the distillation efficiency decreases (Smith, 2005).