Tulsa Environmental Considerations? for Styrene from Toluene and Methanol HW I just want you to write one page about Health, safety, and environmental cons

Tulsa Environmental Considerations? for Styrene from Toluene and Methanol HW I just want you to write one page about Health, safety, and environmental considerations for the topic Styrene from Toluene and Methanol E. Health, safety, and environmental considerations.and please see attachedthanks ChE 4083 Chemical Engineering Plant Design Spring, 2020
Project 2
Styrene from Toluene and Methanol
INTRODUCTION
Styrene monomer (SM) is currently produced in a two‐step process from benzene and ethylene.
First, benzene is alkylated with ethylene to form ethylbenzene (EB). After purification, the
ethylbenzene is catalytically dehydrogenated to produce styrene. The dehydrogenation step is
endothermic and requires a large quantity of steam mixed with the ethylbenzene to maintain
the desired reaction temperature, to depress coking of the catalyst and to dilute the reaction
concentration to enhance the reaction equilibrium.
Our research department has discovered a catalyst which will produce styrene from toluene
and methanol in one step. Steam addition is not required. Some byproduct ethylbenzene is also
produced which can be sold to conventional styrene producers. This catalyst discovery might
give us the opportunity to develop a new, low‐cost route to styrene.
The need, therefore, is to synthesize a flowsheet and prepare a preliminary design and
economic evaluation for a new process which would produce styrene from toluene and
methanol.
STATEMENT OF THE PROBLEM
Your assignment is to:
1. Synthesize the optimum flowsheet and material balance for the new styrene process
(final purification of crude styrene is beyond the scope of your assignment).
2. Size and estimate the costs of the major pieces of equipment.
3. Estimate the installed equipment capital cost.
4. Estimate the manufacturing cost.
5. Estimate the after‐tax profitability of the optimum process. Base the estimate on the
following assumptions: 10 year life, 48% income tax, 2% inflation rate, 15% MARR, and
working capital as 15% of the manufacturing capital. Also assume the following sales
values and product charges:
Product Values
Crude Styrene product
Ethylbenzene byproduct
Administration, Distribution, Marketing and
R&D Costs
$1.74/kilogram
$1.36/kilogram
$0.17/kilogram of crude styrene product
DESCRIPTION OF THE NEW STYRENE PROCESS
The overall process is shown in Figure 1, with the proposed reaction step already synthesized
by our R&D personnel. The optimum design may require additional heat exchangers. The
separation steps, however, have not been designed.
The saturated vapor (at 570 kPa) feed streams of toluene and methanol are mixed,
superheated in an interchanger and fired heater, and then fed to a catalytic reactor where the
following reactions take place:
Toluene + Methanol ⇄ Styrene + Water + Hydrogen
Toluene + Methanol ⇄ Ethylbenzene + Water
For this preliminary evaluation, we can assume that byproduct formation and polymerization
of styrene monomer are negligible and that the catalyst does not coke or deactivate with
time.
Heat is recovered from the reactor effluent in an interchanger before the effluent is
condensed with cooling tower water (CTW) and cooled to 38°C.
REACTOR PERFORMANCE
Research has taken the following data for determining the adiabatic reactor performance. Use
linear interpolation between temperatures for intermediate values.
Inlet Temperature, °C
Inlet pressure, kPa abs.
Conversion
Yield
Rate
480
400
0.68
0.87
36
495
400
0.71
0.83
73
510
400
0.76
0.78
130
Conversion moles toluene reacted/moles toluene fed
Yield moles styrene formed/moles toluene reacted
Rate gmoles toluene reacted/m3 catalyst/min
525
400
0.82
0.72
190
In collecting these reactor performance data, research used only stoichiometric feed to the
reactor. Therefore, your design should be based only on stoichiometric feed (i.e., equal moles
of toluene and methanol).
DESIGN DATA
(Including Simplifying Assumptions)
A. Material Balance
The proposed plant capacity is 300,000 metric tons per year of crude styrene monomer, which
includes 300 ppm of contained ethylbenzene. The onstream time is 95% (8,320 hours per year).
Yield losses due to trace byproducts have been ignored.
Impurities in purchased methanol and toluene are negligible.
Water, EB and SM recycled to the reactor feed are at small enough concentrations to pass
through as inerts.
B. Three‐Phase Separator
The reactor effluent condensed with cooling tower water forms three phases: organic, aqueous
and vapor phases. (Phase phenomena are given below.) The vapor phase will not be processed
in this preliminary design but will be given a fuel‐value credit. Also, the aqueous phase will not
be processed in this preliminary design. The organic phase will be processed to recover
unreacted toluene and methanol for recycle and to purify the styrene and ethylbenzene
streams to meet specifications.
For sizing the Decanter, use 30 minutes liquid holdup time and 60% liquid‐full.
The lowest acceptable process outlet temperature for all water‐cooled heat exchangers is 38°C
and is limited by the cooling tower water supply temperature.
1. VAPOR PHASE
The off‐gas will be given a credit as fuel at its lower heating value.
2. AQUEOUS PHASE
Except for methanol, negligible organics will partition into the aqueous phase.
The partition coefficient for methanol is 1.40 (ratio of mole fraction in the organic phase to
mole fraction in the aqueous phase).
Design of a column to separate methanol and water is not required for this evaluation, since
this separation can be achieved elsewhere in the existing plant. However, the overall plant
material balance must include the methanol/water separation in order to define recycle
streams. Neglect water in the recycle methanol and neglect methanol losses. Ignore the cost of
the methanol/water separation for this evaluation. Methanol recycle is saturated vapor at 570
kPa.
3. ORGANIC PHASE
Negligible water will partition into the organic phase. (Thus, only methanol partitions into both
organic and aqueous phases.)
C. Distillation
1. Nominal‐atmospheric distillations will operate at 136 kPa top tray pressure and 123 kPa
condenser outlet pressure. Avoid column operating pressures above nominal atmospheric.
Allow 5 kPa pressure drop between the top of the column and the condenser outlet for
vacuum columns.
2. Do not exceed 145°C in any column with more than 50 wt% SM in the bottoms, in order to
minimize SM polymerization.
3. Sieve tray columns will be assumed for all distillations. Tray spacing is 60 cm (24 inches).
4. Use 10 minutes holdup time and 60% liquid‐full for sizing the reflux drums.
5. Aromatic Phase Specifications:
Recycle methanol
No specified limit on toluene
Recycle toluene
No specified limit on methanol
4 wt% EB maximum
5 wt % maximum for sum of EB and SM
EB byproduct
0.8 wt% toluene maximum
3 wt % SM maximum
Crude SM product
300 ppm EB maximum
D. Equipment Pressure Drop
For preliminary design, the following pressure drops may be assumed:
Fired heater
110 kPa
Reactor
70 kPa
Heat exchangers
35 kPa for liquid or vapor streams with no phase change
10 kPa for boiling liquids or condensing vapor (non‐vacuum)
Condensers under vacuum 5 kPa
Distillation Trays:
1.0 kPa per theoretical stage for pressure columns
0.6 kPa per theoretical stage for vacuum columns
Other major equipment
13 kPa
Negligible pressure drop through piping may be assumed.
E. Heat Transfer Coefficients
The following overall heat transfer coefficients may be assumed, kcal/hr/m2/°C:
SYSTEM
Gas/Gas
Gas/Liquid
Gas/Boiling Liquid
Gas/Condensing Vapor
Liquid/Liquid
Liquid/Boiling
Liquid Liquid/Condensing Vapor
Boiling Liquid/Condensing Vapor
OVERALL
COEFFICIENT
50
100
200
200
500
700
700
1000
F. Compression Efficiency
The isentropic compression efficiency can be assumed to be 80%. The combined mechanical
and electrical efficiency is approximately 90%.
ECONOMIC DATA
The cost data given here are tentative, and appropriate only for preliminary economic
evaluations. All costs are for the Houston Gulf Coast, where the plant will be located.
A. Capital Costs
For this preliminary design, only the major pieces of equipment need to be designed and cost‐
estimated.
Storage tanks are not included in this evaluation.
The installed equipment cost (i.e. manufacturing capital) can he estimated by multiplying the
sum of the major equipment costs by the Lang factor ( 5). Assume that no spare items are
required.
You can estimate the equipment costs using the factors given in the table below, with costs
adjusted for size by the following equation:
Equipment Cost
Referenced Cost
Required Size
Referenced Size
Exponent
EQUIPMENT COST (2021 DOLLARS)
Equipment
Type
Referenced Cost
($K)
12.9/tray
Referenced Size
Exponent
Distillation
Column, with
Trays
Fired Heater
Sieve Tray
2.54 meter
diameter
1.24
680
21 X 109 joules/hr 0.63
800
2.69 X 109
joules/hr
93 meter2
0.74
Reactor
Box‐type, Gas
fired
Centrifugal,
Electric drive
Fixed tubesheet,
19 mm ID tube, 6
m length
Pressure Vessel
0.30
Catalyst
Vaporizer
Tank
Pellets
Horizontal tube
Separator
1.8
263
12.6
3.8 meter3
catalyst
100 liter
93 meter2
3.8 meter3
Gas Compressor,
with driver
Heat Exchanger
40.7
96
0.69
1
0.56
0.56
Other equipment costs may be estimated from the literature. Use 2021 as the base year to
purchase the equipment and to build the plant. Depreciation begins in 2022.
B. Manufacturing Costs
Since plant startup is targeted for 2022, the manufacturing costs given below are based on that
year.
(Basis of units: K = thousands, M = millions, 2022 dollars)
Raw Materials:
Methanol
Toluene
$0.38/kilogram
$0.84/kilogram
Credits:
Off‐gas from three‐
phase separator
$6.20/M kilojoules
Utilities:
Natural gas*
Steam
2865 kPa, sat’d.
625 kPa, sat’d.
Cooling water
Inlet temp., ave.
Outlet temp., ave.
Electricity
Condensate and Boiler
feed water
$5.10/M kilojoules
$19.00/K kilograms
$13.40/K kilograms
$0.035/K liters
31°C
41°C maximum
$0.07/kWH
$1.35/K liters
Direct Manufacturing Expenses:
Operating labor**
Supervision
Payroll charges
Repairs
Factory supplies
Lab charges
Waste disposal
Technical service
Depreciation
$40/hr
50% of Labor cost
30% of (Labor + Supervision)
4% of (Mfg. Capital)/yr
0.3% of (Mfg. Capital)/yr
0.4% of (Mfg. Capital)/yr
2% of (Mfg. Capital)/yr
0.8% of (Mfg. Capital)/yr
MACRS (5 yr)
Indirect and Other Expenses
6% of (Mfg. Capital)/yr
* Assume 90% efficiency for the fired heater fuel usage
** 840 hrs/week total operating labor
REPORT FORMAT
The final report should include the following:
l. Cover letter
2. Executive Summary: Give a brief review of the work done and tools used.
3.Introduction: Give a concise statement of the problem, covering background and
objectives.
4. Process: Present the process flow diagram for the selected scheme, showing basic control
instrumentation and points of measurement.
5. Discussion: Present the details of the work done, including an explanation for each of your
design choices. Include appropriate data, calculations, assumptions, diagrams, references,
etc.
6. Conclusions: List the major conclusions, in decreasing order of importance. The
conclusions must flow logically from the summary (i.e., new material is not introduced
here.)
7. Recommendations: List actions, goals, and other recommendations, in decreasing order of
importance. The recommendations must flow logically from the conclusions.
8. Appendices
A. Stream summary: include temperature, pressure, vapor fraction, total molar flow rate,
and component mole fractions for each stream.
B. Equipment summary: include description, function, size, materials of construction,
operating conditions, and purchase cost.
C. Utilities summary, showing duty, consumption, and cost for each major equipment
piece.
D. Economic calculations: include cash flow analysis with line‐by‐line explanation.
E. Health, safety, and environmental considerations.
F. Computer process simulator documentation.

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