Production of Vinyl Acetate Monomer (VAM)

Final Design Report

University of Hull

School of Chemical Engineering

Abstract

This report is focused on the design of aspects of a Vinyl Acetate Monomer (VAM) production plant, the process description as a whole and the design of the reactor. The report describes how the process will be operated, through the use of a process flow diagram (PFD) and a mass balance across the PFD to demonstrate the total amount that is inputted and outputted throughout the plant. It will also demonstrate how the reactor was designed, including heat transfer, sizing, and costing calculations to accurately produce a reactor capable of the specified 300,000 tonnes per annum of VAM. It demonstrates how work that was done before the closure of the University due to COVID-19 was performed as a group, and how the work has been adapted to reflect on the lack of group cohesion following the closure of the University. The report found that a catalytic tubular reactor was the best design based on the design conditions such as a highly exothermic reaction, meaning tubular coolers were required to keep the temperature within an acceptable range.

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CONTENTS

Account of Work Done So Far (Introduction) ...................................................................................... 5

Design Of Unit Operation – Reactor..................................................................................................... 7

Choice of Reactor Type .................................................................................................................... 8

Required Data for Reactor Design .................................................................................................... 8

Reactor Conditions ......................................................................................................................... 12

Choice of Material .......................................................................................................................... 13

Cost Estimation of the Reactor ....................................................................................................... 14

P&ID of the reactor......................................................................................................................... 15

Overall Design ................................................................................................................................ 17

Area of Process Responsibility – Process Description ........................................................................ 18

Conclusion.......................................................................................................................................... 23

References .......................................................................................................................................... 24

Appendix ............................................................................................................................................ 25

Appendix A: Group Meetings......................................................................................................... 25

Appendix B: PFD............................................................................................................................ 29

Appendix C: Mass Balance............................................................................................................ 32

Appendix D: Reactor Design Calculations...................................................................................... 35

List of Figures

Figure 1 - Final PFD of the VAM production process............................................................................. 6

Figure 2 - Preliminary Mass Balance prior to COVID-19........................................................................ 7

Figure 3 - P&ID for the reactor........................................................................................................... 16

Figure 4 - Process Data Sheet for the Reactor .................................................................................... 17

Figure 5 - PFD of VAM plant................................................................................................................ 20

Figure 6 - Mass Balance of VAM production Plant.............................................................................. 21

Figure 7 - Group Meeting 1................................................................................................................. 25

Figure 8 - Group Meeting 2................................................................................................................. 26

Figure 9 - Group Meeting 3................................................................................................................. 27

Figure 10 - Group Meeting 4............................................................................................................... 28

Figure 11 - Group Meeting 5............................................................................................................... 28

Figure 12 - Initial preliminary PFD design ........................................................................................... 29

Figure 13 - Second draft of PFD design ............................................................................................... 29

Figure 14 - Third Draft of PFD design .................................................................................................. 30

Figure 15 - Fourth Draft of PFD design................................................................................................ 31

Figure 16 - Final PFD Design................................................................................................................ 31

Figure 17 - Reactor mass balance hand calculations........................................................................... 32

Figure 18 - Enthalpy of feed hand calculation..................................................................................... 35

Figure 19 - Enthalpy of products hand calculation.............................................................................. 36

Figure 20 - Heat Transfer Coefficent hand calculation........................................................................ 37

Figure 21 - Area of heat exchanger hand calculation.......................................................................... 38

Figure 22 - Catalyst hand calculations................................................................................................. 38

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Figure 23 - Reactor wall thickness hand calculations.......................................................................... 39

Figure 24 - Reactor cost hand calculations ......................................................................................... 40

List of Tables

Table 1 - Mass Balance across the reactor ............................................................................................ 9

Table 2 - Heat duty Data ..................................................................................................................... 10

Table 3 - Input and Output Analysis.................................................................................................... 22

Table 4 - Annual Inputs and Outputs for the VAM Plant..................................................................... 23

Table 5 - Reactor mass balance including impurities .......................................................................... 33

Table 6 - Flash Separator Mass Balance.............................................................................................. 33

Table 7 - Absorber-Stripper mass balance .......................................................................................... 33

Table 8 - Distillation Column 1 mass balance...................................................................................... 34

Table 9 - Distillation Column 2 mass balance...................................................................................... 34

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ACCOUNT OF WORK DONE SO FAR (INTRODUCTION)

The basis for the final report of Vinyl Acetate Monomer (VAM) production is based on information that was obtained in the technology selection report. This report gave an overview of the properties and uses of VAM, a market analysis of VAM at recent price points, as well as an analysis of three potential process routes for VAM production. It was concluded that the best method in terms of profitability, environmental impact and overall safety was the route of Ethylene, Oxygen and Acetic Acid. This was discussed during our first group meeting and we all had come to the same conclusion, and we therefore decided that we would design our process around this route. Unfortunately unforeseen circumstances due to COVID-19 have meant that the completion of group work has not been possible; however, it is important to acknowledge the work that has been done prior to COVID-19, because a substantial amount of work was completed as a group before this event.

The first thing we did was to all agree on the process route, which was completed in the first meeting as seen in the Appendix A. This was incredibly simple as we had all drawn the same conclusion in our technology selection reports. The next step was to assign each unit operation in the process to a group member. This would ultimately be the unit operation that we would each design in detail. The unit operations were assigned as seen in Appendix A. Once we had assigned our unit operations, the next step was to begin to build the PFD (process flow diagram) for VAM production. We thought this would be the best starting point for the design process so that we were all aware of the process streams that would be coming in and out of our separate unit operations.

The PFD was designed by every member of the group. We decided that the best way to do this would be to first analyse PFDs that have been researched and designed by others, such as those done by Dimean and Bildea (2011) and Luyben (2011), in order to establish a baseline of design for VAM production. This allowed us to begin to design our own plant with improved modifications to previous designs. We designed the PFD using a program called Visio, which is a diagramming application which was very suitable for producing a PFD. We began by inserting our five-unit operations that were assigned and inputting any necessary process streams that needed to be attached. We then added any other necessary unit operations that were essential for the process. For example, a decanter was necessary to achieve the 99.9% VAM purity. The final step for initial design was to add in two recycle streams, one for the acetic acid and one for the ethylene gas. The first draft for our PFD was submitted on the 11th February 2020. Alterations and improvements to the PFD were made over time, as seen in Appendix B. It should however be noted that the most up-to-date design that was produced was done before the disruption of COVID-19, and therefore it will be considered as the final design even though further modifications would have been made. A detailed diagram and description of the PFD will be