CHE231 - Final Year Report Plant Design: Production Of Styrene (2016) PDF

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PLANT DESIGN FOR PRODUCTION OF STYRENE 2016 EXECUTIVE SUMMARY Styrene who is also known as ethylbenzene,vinybenzene and phenylethene is an organic compound with the chemical formula C6H5CH=CH2. Although styrene was discovered way back in 1839, its commercial production and applications were develope...

Description

PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

EXECUTIVE SUMMARY Styrene who is also known as ethylbenzene,vinybenzene and phenylethene is an organic compound with the chemical formula C6H5CH=CH2. Although styrene was discovered way back in 1839, its commercial production and applications were developed in the 1930s. Post world war period witnessed a boom in styrene demand due to its application in the manufacture of synthetic rubber. This led to a dramatic increase in styrene capacity. Styrene has wide application in producing plastic and synthetic rubber industry. It is mostly used in manufacturing

of

polystyrene (PS),

acrylonitrile-butadiene-styrene

(ABS),

styrene-

acrylonitrile (SAN), styrene-butadiene rubber (SBR) and lattices, unsaturated polyester resins (UP resins) and miscellaneous uses like textile auxiliaries, pigment binders polyester resin, aromatics and intermediate industries. Worldwide, there are commonly five methods of manufacturing of styrene such as catalytic dehydrogenation of ethylbenzene, Oxidation of ethylbenzene to ethyl hyroperoxide , side-chain chlorination of ethlybenzene followed by dechlorination, side-chain of chlorination of ethylbenzne hydrolysis to the corresponding alcohols followed by dehydration and pyrolysis of petroleum recovery. In an effort to find a sustainable method of manufacturing of styrene from ethylbenzene, several design objectives were chosen as a necessity for the proposed system such as identifying suitable catalyst, the economic factor, environmental factor, strategic location to build for styrene plant, the design specifications on the reactors and distillation column used in the plant, the market price and also not to forget the safety issue relating to the plant. Obtaining this data was very crucial before scaling up the design of a complete industrial plant. For the final design of our project, we includes the process flow diagram (PFD) and also Piping and Instrumentation Diagram (P&ID) created by Microsoft Visio, finalized site selection to build the styrene plant, the analysis of reactor and distillation design plus with HAZOP study and FTA analysis in concerning safety relating issue toward the each equipment used in the process background of producing styrene. From this variable aspect, we conclude the proposed plant design would indeed be economically viable and profit inducing.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

TABLE OF CONTENT EXECUTIVE SUMMARY .................................................................................................................... 1 ACKNOWLEDGEMENT ...................................................................................................................... 3 ABSTRACT............................................................................................................................................ 4 INTRODUCTION .................................................................................................................................. 5 PROBLEM STATEMENT ..................................................................................................................... 6 OBJECTIVES ......................................................................................................................................... 7 PROCESS SELECTION ........................................................................................................................ 8 PROCESS BACKGROUND ................................................................................................................ 10 Material Balance For The Production Of Styrene............................................................................. 11 Sizing For Primary Distillation Column (Multi-Component Distillation) ........................................ 15 1)

Bubble and Dew Point By Trial Calculation,........................................................................ 15

2)

Relative Volatility, ................................................................................................................ 15

3)

Minimum Number of Theoretical Stages,............................................................................. 17

4)

Minimum Reflux Ratio, ........................................................................................................ 18

5)

Operating Reflux Ratio and No of Stages, ............................................................................ 19

6)

Column Diameter, ................................................................................................................. 20

7)

Feed Location,....................................................................................................................... 21

Block Flow Diagram (BFD) For Styrene Production ...................................................................... 22 Process Flow Diagram (PFD) For Styrene Production ..................................................................... 23 Piping and Instrumentation Diagram (P&ID) For Styrene Production ............................................. 24 Process Equipment Symbols and Numbering ................................................................................... 25 Plant Layout ...................................................................................................................................... 27 SITE SELECTION ............................................................................................................................... 28 HAZARD AND RISK ASSESSMENT ................................................................................................ 35 Hazard And Operability Studies (HAZOP) ...................................................................................... 35 Fault Tree Analysis (FTA) ................................................................................................................ 36 Material Safety Data Sheet (Styrene)................................................................................................ 37 Safety ................................................................................................................................................ 41 CONCLUSION ..................................................................................................................................... 42 REFERENCES ..................................................................................................................................... 43

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

ACKNOWLEDGEMENT We would like to express our deepest appreciation to those who help in providing us helpful information and contribute directly or indirectly which led to the completion of the report. Special gratitude to our lecturer, Encik Omar Syah Jehan, who guide us in the selection of idea and give the best suggestion and step-by-step guidelines for during the improvement of the report. Last but not least, bundle of thank you for all the team member whose invested the highest effort, time and energy in achieving the objective of the report.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

ABSTRACT The production of styrene is a 28 billion dollar industry worldwide. There is a significant demand for it and cutting costs even a few cents per pound will yield large savings. These savings can then be passed to the consumer and will ultimately make styrene products (like polystyrenes and ABS polymers) available to more people worldwide. We believe it is feasible to simulate a process for producing styrene that will make this possible. The idea is to use cheaper raw materials, namely ethane instead of ethylene, and utilize the fundamentals of the process, such as a dehydrogenation unit, to convert the ethane to ethylene in the process. An advantage to the new process is that it starts with a less expensive raw material, ethane, instead of ethylene.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

INTRODUCTION Styrene is the precursor to polystyrene, which is used in plastics, protective coatings, polyesters, resins, and chemical intermediates. Styrene also can be used as the yeast-like fungus Exophiala jeanselmei that can be used to treat air polluted with styrene. The IUPAC name for styrene are Vinyl benzene, Cinnamene, Styrol, Phenylethene, Diarex HF 77, Styrolene,

Styropol,

Vinylbenzene,

Phenylethylene

is

an organic

compound with

the chemical formula C6H5CH=CH2. This derivative of benzene is a colourless oily liquid that evaporates easily and has a sweet smell, although high concentrations have a less pleasant odour. Styrene is the precursor to polystyrene and several copolymers. The chemical structure of the styrene is shown in the figure 1.1. The production of styrene using many equipment such as reactor (with floating head shell and tube), reactor feed heating system (3 unit), reactor effluent cooling system (2 unit), 3-phases separator, pre-separating effluent heat exchanger, column 1, column 2, column 3 and column intermediate cooling system.

Figure 1 – Ethyl Benzene Molecular Structure A by-product of the process is diethyl benzene (DEB) that is an intermediate in divinyl-benzene manufacture. Since the demand for styrene is far greater than the demand for divinyl-benzene, the selectivity for our process should favour ethyl benzene production. Ethyl benzene is produced by coupling ethylene and benzene with an acidic catalyst. Diethyl benzene forms when ethylene reacts with ethyl benzene. The formation of multiplysubstituted benzenes is limited by running the reaction with a large excess of benzene.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

The reactions that produce Ethyl Benzene and Diethyl Benzene are

Where,  is the extent of reaction. The selectivity of these reactions is determined by the feed ratio and processing conditions.

As we know that production of styrene can jump into polystyrene so it is the profitable production due to the high demand from the customer to produce the polystyrene. Consumer demand for styrene derived products may fluctuate as well with less use of plastics and polystyrene products amid environmental concerns. As a result, the selling price of styrene could decrease and potentially affect profitability. Competitors in the market for styrene production may also influence the cost value of products, as well as the enterprise rate. Styrene 2016 World Market Outlook and Forecast up to 2020 grants access to the unique data on the examined market. Having used a large variety of primary and secondary sources, the research team combined, canvassed and presented all available information on product in an all-encompassing research report clearly and coherently as shown in figure 1.2.

Figure 2 - Global Styrene Demand Based On Styrene 2016 World Market Outlook and Forecast up to 2020

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

PROBLEM STATEMENT Currently, there are many methods in producing styrene. However the problem lies on the selection of the best method to produce styrene in large scale in order to satisfy the demand of the compound which expected to increase by years. The current method for producing styrene in small scales utilizes ethylene as a starting material. However, it is hard to break through into the styrene market without planning a plant of massive capacity. Besides, if a new, cheaper starting material can be used, the cost of production can be significantly reduced and the market undercut with less capital cost than by sheer capacity. The selection and the cost of raw material, utilities, equipments, location and other few factors need to take into consideration to design the plant for the mass production of the wanted product, Styrene.

OBJECTIVES 1) Designing full scale mass production industrial plant to produce styrene from ethyl benzene as the main raw material. 2) Identifying suitable catalyst for the reaction to proceed optimally. 3) Evaluate the plant design based on economic and environmental factor. 4) Our plant will be optimized to produce styrene below the current production cost by utilizing new technology and building a plant of with large capacity to be cost efficient. 5) Simulating complete plant design using HYSYS. 6) Choosing the strategic location for the plant to be built. 7) Determine the design specifications on the following pieces of process equipment such as compressors, turbines, pumps, heat exchangers, distillation columns and reactors. 8) Analyse the design to determine whether it is economically competitive at the average market price. 9) Determining the safety issues relating to the design of the plant.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

PROCESS SELECTION Styrene is the precursor to polystyrene and several copolymers. Approximately 25 million tonnes of styrene were produces in 2010 [1]. There are many methods in producing Styrene which are:1) Catalytic Dehyrogenation of ethyl benzene, 2) Oxidation of ethyl benzene to ethyl benzene hyroperoxide which reacts with propylene oxide after which the alcohol is dehydrated to styrene. 3) Side-chain chlorination of ethyl benzene followed by dechlorination. 4) Side-chain chlorination of ethyl benzene hydrolysis to the corresponding alcohols followed by dehydration. 5) Pyrolysis of petroleum recovery from various petroleum processes.

Method 2 is one of the commercialize process to produce styrene from propylene oxide. In this process ethyl benzene is treated with oxygen to form ethyl benzene hydroperoxide. Then, it is used to oxidize propylene to propylene oxide. The resulting phenyl ethanol is dehydrated to give styrene.

Figure 3 – Reaction Of Ethyl Benzene with Oxygen to Produce Propylene Oxide which then led to Production of Styrene

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

Method 3 and 4 involved the use of chlorine, it have been generally suffered from high cost of raw materials and from the chlorinated contaminants in the monomer whereas method 5 the pyrolysis petroleum recovery from various petroleum process is not widely available since manufacturing styrene directly from petroleum streams is difficult and costly. Besides, the problem with pyrolysis process is that carbon is catalyst poison making more cost needed to reactivated back the catalyst.

The best process to produce styrene in large scale is method 1 which is catalytic dehydrogenation of ethyl benzene. This process is the primary commercialize process for production of styrene about 85% of the industrial process used nowadays. Ethyl benzene is reacted with catalyst usually iron oxide to produce styrene.

Figure 4 – Reaction of Ethyl Benzene to Produce Styrene

This process reaction is equilibrium

limited and with the addition of steam, the

process can be controlled. During the process, the steam does not react with ethyl benzene and the catalyst which prevents coking from happen. The advantages of diluting ethyl benzene with superheated steam in this process is :-

1) It lowers the partial pressure of ethyl benzene and shift of equilibrium towards higher styrene production and minimizing the loss to thermal cracking, 2) Supplies part of the heat needed for endothermic reaction, 3) Decrease carbonaceous deposits by steam reforming reaction, 4) Avoid catalyst over reduction and deactivation by controlling the state of the iron.

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

PROCESS BACKGROUND The team has decided to go with catalytic dehydrogenation of ethyl benzene since it is widely used nowadays. The raw materials need to considered is also minimum which only consist of ethyl benzene, catalyst and steam generation.

The process begins with fresh ethyl benzene 160 MT/hr fed to a Mixer-1 where after one process complete , the unreacted ethyl benzene will be recycled back into Mixer-1 where combination of both the fresh and the recycled one is approximately about 26 MT/hr. They flow to Mixer-2 and mix with superheated steam about 640 MT/hr. The steam to feed ratio is 4:1. Then, they go the Furnace Heater, Dowtherm Heater and Molten Salt Heater respectively to dilute the ethyl benzene to enhance the conversion toward styrene before fed to Isothermal Packed Bed Reactor. The reactor is where the conversion of ethyl benzene to styrene occurs by contacting the diluted ethyl benzene with iron oxide (Fe3O4) catalyst. The reactor effluent is then flow through Molten Salt Cooler and Dowtherm Cooler before fed to 3-phase Separator where Vapor Silt (48 MT/hr) , Waste water (640 MT/hr) and Organic Liquid Split (112 MT/hr) is separated. The organic liquid split composition is Benzene, Toluene, Ethyl Benzene and Styrene where they need to undergo distillation to extract the wanted product which is Styrene . After the organic liquid split left the separator, it fed into flash tank where approximately about 12 MT/hr of vapor split is released.

The organic liquid split then go to a distillation column where Benzene-Toluene and Ethylbenzene-Styrene is separated according to their boiling point. The distillate stream go to another distillation column, second distillation column where Benzene and Toluene is further separated whereas the bottom stream of the first distillation column, go to the third distillation column where Styrene and Ethylbenzene is separated. The styrene is the main product to satisfies the demand is stored into storage vessel while the ethyl benzene that is recovered from the process is recycled back to Mixer-1 .

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

Material Balance For The Production Of Styrene The basis of the feed stream is 160MT/hr of ethylbenzene. The team made assumptions of the following condition at the reactor in order to produce about 54MT/hr of styrene :1) Fractional conversion of the ethylbenzene to styrene and benzene is about 37.5% of the feed, 2) The selectivity of styrene over benzene to be 90%, 3) Fractional conversion of ethylbenzene to toluene is about 14% of the ethylbenzene balance of the main reaction, 4) The total conversion of ethylbenzene is about 83.75% .

160 MT/hr

160 MT/hr 1.0000 Ethylbenzene

Reactor

0.1625 Ethylbenzene 0.3375 Styrene 0.2500 Hydrogen gas 0.0375 Ethylene 0.0375 Benzene 0.0875 Toluene 0.0875 Methane

Figure 5 – The Composition of The Components On The Reactor Streams Table 1 - The Mass Flow Rate and Composition of the Component Present At The Reactor Input Output Component Mass Flow Composition Component Mass Flow Composition Rate Rate (MT/hr) (MT/hr) Ethylbenzene 160 1.0000 Ethylbenzene 26 0.1625 (C8H10) (C8H10) Styrene 54 0.3375 (C8H8) Hydrogen 40 0.2500 (H2) Ethylene 6 0.0375 (C2H4) Benzene 6 0.0375 (C6H6) Toluene 14 0.0875 (C7H8) Methane 14 0.0875 (CH4) Total 160 1.0000 Total 160 1.0000

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PLANT DESIGN FOR PRODUCTION OF STYRENE

2016

Since the production of styrene under high temperature using steam technology where the steam was first mix with the ethylbenzene before fed to the reactor, there are presence of water (H2O) molecule at the effluent stream, however since the molecule does not take part in the reaction and considered inert, it is negligible in the calculation. The effluent of the reactor is then, fed to three-phase separator to remove the byproduct gaseous and most of the water present in the effluent mixture. ...