Process Flow Table

. PFD, mass and energy balance

In this Chapter the overall process flow diagram (PFD), with process description, mass and energy balances are presented. These balances are based on the ASPEN PLUS v8.2 simulation of the proposed design. The calculated overall plant mass balance and the key unit mass balances are presented in section 6.2. The energy balance will be provided in section 6.3 as well as the possible heat integration.

6.1 Process flow diagram

The process flow diagram can be found in Appendix S – Process flow diagram. In this section the flow sheet will be explained and clarified. The first process step is the preparation of the feed flows for the reactor. All feeds and recycles are pressurized to 14 bar to overcome pressure drops and remain at a pressure of 12 bar at the reactor outlet (P01-P07). The fresh benzene feed (stream 06) is first mixed with the recycle benzene (stream 39) in the benzene mixer (M04). Fresh solvent is mixed (M02) by mixing fresh

The reboiler temperature (calculated using ASPEN) is 212 °C. The column has 30 stages, a reboiler pressure of 2 bar and a reflux ratio of 0.11. Benzene leaves the column at the top (stream 31). From the top stream 2 wt% is purged (stream 38) and the remainder is recycled at 72 °C. The bottom product contains mainly aniline and phenol. This stream is cooled (E09) and the phenol is washed out (C05) using sodium hydroxide solution. The formed sodium phenolate is separated and send to outside battery limit (stream 35). The aniline product is retrieved from the wash column and send to outside battery limit (stream 33).
6.2 Overall mass balance

Using Aspen, mass balances are generated. The methodology of the aspen simulation is given in Appendix T – Aspen Simulation. Table 6 gives the overall mass balance of the plant. All incoming and outgoing streams are summed to check whether the law of conservation of mass is not