AIChE National Student Design Problemcourses.engr.uky.edu/CME/cme456-001/cme 456 2018... · Dear AIChE Contest Judges, ... 10 12 - 15 Tensile Strength (psi) ~ 12,000 ~ 10,150 Since

AIChE National Student Design ProblemChris Fugate and Jared Wittrock University of Kentucky, College of Engineering Chemical and Materials Engineering 177 F. Paul Anderson Tower Lexington, KY 40506-0046 March 8, 2017 AIChE Headquarters 120 Wall Street, FL 23 New York, NY 10005-4020 Dear AIChE Contest Judges, The purpose of sending this proposal is to provide a thorough and accurate process depicting the needed production of Nylon 6,6. The report will go through the process step-by-step, economics of each process option, safety considerations for the process, and other factors to be considered when developing a chemical process. We believe that the proposal submitted is the best solution to the problem presented for the production of Nylon 6,6 as research from universities and companies are in coordination with our results. Your time and consideration for this proposal is greatly appreciated. If there are any questions regarding the proposal, please feel free to contact us at [email protected] and [email protected]. Sincerely, Chris Fugate and Jared Wittrock

2017 AIChE National Student Design Competition

University of Kentucky Department of Chemical and Materials Engineering

Chris Fugate & Jared Wittrock

TableofContents

Abstract.................................................................................................................................1

Introduction..........................................................................................................................2

Process Flow Diagram and Material Balances......................................................................3

Process Description...............................................................................................................6Design Database..............................................................................................................................6Design Assumptions.........................................................................................................................6MATLAB Modeling for Batch Process.............................................................................................7

Kinetics................................................................................................................................................7Mass Balances.....................................................................................................................................7Molecular Weight Distribution..........................................................................................................10Energy Balance.................................................................................................................................10

Description of Process....................................................................................................................11Initial Mixing of Reactants................................................................................................................11Polymerization...................................................................................................................................12Extrusion #1, Chip Formation, and Evaporation of Cooling Water..................................................23Extrusion #2 – Melting and Homogenization and Filtration.............................................................24Spinneret System and Stretching for Final Product Properties.........................................................24Cycle Time Summary.........................................................................................................................25Control Systems Summary.................................................................................................................25Quality Control and Assurance.........................................................................................................26Plant Layout......................................................................................................................................27

Utility Requirements............................................................................................................27

Equipment List and Unit Descriptions.................................................................................29

Equipment Specification Sheets...........................................................................................31

Fixed Capital Investment Summary....................................................................................34

Manufacturing Costs...........................................................................................................35Raw Material Costs........................................................................................................................35Utility Costs....................................................................................................................................36Other Major Manufacturing Costs.................................................................................................36

Selling, General, and Administrative (SG&A) Costs...........................................................36

Economic Analysis...............................................................................................................37

Safety, Health, and Environmental Considerations.............................................................43Safety and Health Affects...............................................................................................................43Inherently Safer Design.................................................................................................................44Environmental Affects...................................................................................................................44HAZOP on Base Case: Batch Reactor System................................................................................45

Other Important Considerations.........................................................................................50Synthesis of HMDA to Combat High Raw Material Prices.............................................................50Patent Availability and Product Lifecycle.......................................................................................51

Exploring Additive Options for Nylon 6,6.......................................................................................52Increase in Demand Over Time/Decrease of Price – Further Commercialization...........................54

Conclusions and Recommendations.....................................................................................55

Acknowledgements...............................................................................................................56

1

Abstract The production of Nylon 6,6 is a highly endothermic process that can be produced

through the use of either a batch or continuous system utilizing adipic acid and hexamethylene-

diamine as monomers. A batch, continuous, and an alternative case that employs both batch and

continuous process lines are proposed in the report. The end product of each case discussed is a

Nylon 6,6 fiber, as the Nylon chips created are further processed in order to increase the selling

price by at least $0.40 per pound of polymer. The batch process line is the recommended option

as the process has a better extent of reaction and costs less in the long run. The breakeven point

for the batch process is year 5, while for the other two cases, the breakeven points are years 7

and 6 respectively. The other reason for the batch process being recommended is that the

economics can better handle a decrease in production than the other two cases. One concerning

area for the process is the fact that minor increases in raw material prices and minor decreases in

the selling price of Nylon fibers results in drastic differences in the economics, showing the

process to be very volatile. To help resist some of these pitfalls in the economics, additives such

as Nyrim and Fusabond are explored to expand the process into other markets.

2

Introduction The polymer Nylon comes in many varieties, but the two most popular are Nylon 6 and

Nylon 6,6. The advantages of Nylon 6,6 over many other forms of nylon, including Nylon 6,

include a higher abrasion resistance, thermal resistance, melting point, tensile strength,

crystallinity, and better molecular alignment1. Table 1 provides specific data in support of the

production of Nylon 6,6 over its Nylon 6 counterpart. Nylon 6,6 provides unique advantages in

terms of strength, stiffness, and thermal properties.

Table 11. Physical properties of the most common forms of Nylon are shown.

Property Nylon 6,6 Nylon 6 Glass Transition Temperature (°C) 50 40 Plastic Temperature (°C) 220 160 Melting Temperature (°C) 258 218 Specific Gravity (g/cm3) 1.14 1.14 Refractive Index – Unoriented (N0) 1.58 1.53 Moisture Regain % at 65% Relative Humidity 3.8 4.3 Shrinkage % in Boiling Water 8 - 10 12 - 15 Tensile Strength (psi) ~ 12,000 ~ 10,150

Since Nylon 6,6 is very versatile, it is one of the most widely used thermoplastics in the

engineering industry. For example, Nylon 6,6 is a light material so it is utilized in parachutes, but

the material is also waterproof and can be used in swim gear and machinery.2 Due to its high

melting point and thermal and friction resistance, Nylon 6,6 can be found in offices, airports,

restaurants, and other places that have a lot of foot traffic. Other applications include airbags,

carpets, ropes, hoses, and other household and commercial items that are seen in everyday life.

The most common way of producing Nylon 6,6 is by a polycondensation reaction

between adipic acid (ADA) and hexamethylene diamine (HMDA). The synthesis of Nylon 6,6 is

a highly endothermic reaction, and thus heat must be added to create the reaction temperatures

required for the process. The reaction is reversible and is forced to completion by the removal of

the coproduct water. The equation below shows the overall reaction that occurs during the

formation of Nylon 6,6. A series of reactions leads to a step-growth polymerization in which one

molecule of HMDA attacks one molecule of ADA to form a dimer. This dimer can then react

with other molecules to form trimers, tetramers, and other longer oligomers. As this process is

repeated the chains become long enough so that they are called polymer chains of Nylon 6,6.

3

The formation of Nylon 6,6 can be formed through a batch or continuous process. A

batch reactor must be heated through a thermal jacket to the desired temperature for the batch

reaction to occur. A time for the batch is set, and the polymerization occurs over time. For the

continuous process, the liquid reactants run through the reactor and polymerize over the length of

the reactor in a PFR, and throughout the volume of a CSTR. Both approaches are utilized in

industry and both batch and continuous processing will be compared when making the

recommended decision on how to produce the polymer.

Process Flow Diagram and Material Balances

An overall block flow diagram of the process is depicted in Figure 1. The process

description section will go through this process, step-by-step, and will end with a further and

descriptive P&ID and plant layout. This process is intended to produce 85,000,000 pounds of

Nylon 6,6 per year through a polycondensation reaction between molten adipic acid and HMDA.

Figure 1. A BFD of the production of Nylon 6,6 is shown above. Each step will be detailed further.

egrulke

Sticky Note

probably needs a reference

egrulke

Sticky Note

4

The block flow diagram can be further broken down into process flow diagrams for both

the batch and continuous polymerization processes. Figure 2 shows the process for batch

polymerization right before the first extrusion step. Figure 3 depicts the continuous

polymerization process up until the same point as Figure 2. The end of the process from the first

extrusion up until the final product is produced is the same for either batch or continuous

processing, and is shown in Figure 4.

Figure 2. PFD of the front half of the batch polymerization process.

Figure 3. PFD of the front half of the continuous polymerization process.

egrulke

Sticky Note

this will not work particularly well

5

Figure 4. PFD of the back half of the both polymerization processes.

The specifications of the equipment in each of the PFDs will be explained further in the

process and equipment description sections. The material balances for each batch and the

continuous process of alternative cases 1 and 2 are shown in Table 2. The beginning mass input

should equal the total of the mass output of the final output streams, which includes reactor

output, and the amount vented off during polymerization.

Table 2. Overall material balances for both batch and continuous processes.

Batch Polymer (all in kg/batch) Streams Water HMDA Adipic Acid HCl Nylon 6,6 Input 931.61 3307.05 4158.91 63.52 - Input Total Mass 8461.09 Output of Reactor 10.08 0.43 - 0.01 6351.09 Total of Vent 1575.88 460.09 - 63.51 - Output Total Mass 8461.09

Continuous Polymer (all in kg/h) Streams Water HMDA Adipic Acid HCl Nylon 6,6 Input 2217.00 739.00 739.00 - - Input Total Mass 3695.00 Output of Reactor 4.56 1.59 - - 1160.4 Total of Vent 2394.31 134.12 0.02 - - Output Total Mass 3695.00

egrulke

Highlight

egrulke

Sticky Note

not good to have 14% of monomer coming back...

egrulke

Highlight

egrulke

Highlight

egrulke

Sticky Note

18% of monomer feed, a worse efficiency

6

Process Description Design Database Table 3. Thermophysical properties for all components used in the process.3

Component Formula CAS # MW

Normal Boiling Point

(ºC) Melting

Point (ºC) Adipic Acid C6H10O4 124-04-9 146.142 337.5 151.5 Hexamethylene-damine (HMD) C6H16N2 124-09-4 116.208 204.6 42 Water H2O 7732-18-5 18.015 100 0

Nylon 66 𝐶"#𝐻##𝑁#𝑂# ' 32131-17-

2 226.32 Decomposes 264 Nitrogen N2 7727-37-9 28.014 -195.8 -210 Hydrochloric Acid HCl 7647-01-0 36.458 57 -35

Component Density (g/cm3) Viscosity

Vapor Pressure

(Pa)

Heat of Vaporization

(kJ/kg) Adipic Acid 1.36 4.54 @ 160ºC 3.02E-05 549 Hexamethylene-damine 0.84 - - 4.73E+04 Water 0.995 0.89 @ 25ºC 2.34E-03 2257 Nylon 66 1.14 - - -

Nitrogen 0.00125 0.01781

@ 27.4ºC - 99.7 Hydrochloric Acid 1.18 0.405 @ 118 K 4.23E+06 443 Design Assumptions There were many assumptions made when constructing the design for this process:

• Thermophysical and property data for all components used in the simulation are accurate • Modeling process in terms of amine and carboxylic groups provides accurate depiction of

adipic acid and HMDA concentrations over time • Molecular weight of product modeled correct by modifications of Flory's molecular

weight distribution.4 • Volatile mixture treated as binary mixture for VLE relationships between HMDA and

water • Perfect mixing within the reactor (no spacial variations) • Reaction rates of reactions is independent of molecular weight of polymer • CHEMCAD and Aspen are reliable and accurately model the system

egrulke

Sticky Note

thanks, great table...

7

MATLAB Modeling for Batch Process A polymer unit of Nylon 6,6 (L) is formed through the direct amidation of adipic acid (C)

and hexamethylenediamine (A) with the formation of two water molecules (W). Once the first

unit is formed, amine end groups or polymer units can react with carboxylic groups or other

polymer units to continue the process and form longer polymer chains. Carboxylic end groups

and polymer chains can also decompose to form stabilized end groups (SE). The full kinetic

model for production is shown below:

𝐶 → 𝑆𝐸 +𝑊

𝐿 → 𝑆𝐸 + 𝐴 𝐴 + 𝐶 ⇔ 𝐿 +𝑊

Kinetics The rate equations for the corresponding reactions are shown below:

𝑅" = 𝑘"𝐶4

𝑅# = 𝐶5(𝑘# + 𝑘#4 ∗𝐶8𝐶9)

𝑅; =𝑘<==𝐶9

(𝐶8𝐶4 −𝐶5𝐶?𝐾<==

)

In the above rate equations 𝐶A represents the concentration of species i and 𝐶9 is the total

concentration in the reactor. Expressions and values used for the rate constants in these equations

can be found in Appendix A.

Mass Balances Due to the nature of the reactions involved, it is necessary to consider both liquid and

vapor phases when formulating mass balances for each component. Spatial variations within the

reactor were considered negligible in formulation of balances. The profile of values calculated

for the reaction rates as well as rate of mass transfer to the vapor phase are used to write mass

balances for each component. Water and HMDA are the only components that have observable

impacts in their transfer to the vapor phase.

𝑑𝑉𝐶8𝑑𝑡 = 𝑉𝑅# − 𝑉𝑅; − 𝜐8F

𝑑𝑉𝐶G𝑑𝑡 = −𝑉(𝑅" + 𝑅;)

𝑑𝑉𝐶5𝑑𝑡 = 𝑉(𝑅; − 𝑅#)

8

𝑑𝑉𝐶?𝑑𝑡 = 𝑉 𝑅" + 𝑅; − 𝜐?F

𝑑𝑉𝐶HI𝑑𝑡 = 𝑉(𝑅" + 𝑅#)

𝑑𝜌𝑉𝑑𝑡 = −𝜐

Key parameters used in above equations:

𝑉:𝑣𝑜𝑙𝑢𝑚𝑒𝑜𝑓𝑙𝑖𝑞𝑢𝑖𝑑𝑝ℎ𝑎𝑠𝑒

𝜌: 𝑑𝑒𝑛𝑠𝑖𝑡𝑦𝑜𝑓𝑙𝑖𝑞𝑢𝑖𝑑𝑝ℎ𝑎𝑠𝑒

𝜐AF:𝑚𝑜𝑙𝑎𝑟𝑣𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛𝑟𝑎𝑡𝑒𝑜𝑓𝑠𝑝𝑒𝑐𝑖𝑒𝑠𝑖

𝜐: 𝑡𝑜𝑡𝑎𝑙𝑚𝑎𝑠𝑠𝑣𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛𝑟𝑎𝑡𝑒

The total mass vaporization rate is calculated by comparing the vapor pressure of the mixture to

the pressure of the system. The exact model for mass vaporization is shown below5:

𝜐 = 𝐾 𝑃_<= − 𝑃 𝑖𝑓𝑃_<= > 𝑃𝐾 = 25𝑘𝑔

ℎ𝑟 ∗ 𝑝𝑠𝑖𝑎

𝜐 = 0𝑜𝑡ℎ𝑒𝑟𝑤𝑖𝑠𝑒 The total mass vaporization rate is used to calculate the vaporization rate of each species. The

vent rate of species i is calculated by dividing the mass fraction of species i by its corresponding

molecular weight and then multiplying by the total vent rate.

𝜐AF =𝜔Ag

𝑀A𝜐

Due to HMDA having two amine groups the vent rate of amine species is calculated by

multiplying the HMDA vent rate by two.

𝜐8F = 2𝜐iFjF

To determine appropriate VLE relationships, water and HMDA were treated as a binary system

and a Txy diagram was constructed at the system pressure over a relevant range of temperatures.

9

Figure 5: Txy diagram for HMDA/Water system produced in CHEMCAD. The data points from this graph were used to determine the ratio of the vapor composition of

HMDA to that of water. Table 4: Compositions of HMDA and water over temperature range used to calculate ratio of vapor compositions throughout process duration.

Temp(ºC) Temp(K) yHMD yW204.99 478.14 0 1205.85 479.00 0.009 0.991206.37 479.52 0.011 0.989207.17 480.32 0.013 0.987208.49 481.64 0.015 0.985210.35 483.50 0.019 0.981212.76 485.91 0.023 0.977215.67 488.82 0.024 0.976219.09 492.24 0.035 0.965223.01 496.16 0.044 0.956227.45 500.60 0.054 0.946232.46 505.61 0.067 0.933238.11 511.26 0.084 0.916244.52 517.67 0.106 0.894251.84 524.99 0.134 0.866260.30 533.45 0.172 0.828270.27 543.42 0.225 0.775282.29 555.44 0.302 0.698297.28 570.43 0.420 0.580316.90 590.05 0.618 0.382344.43 617.58 1 0

egrulke

Sticky Note

there will be some mass transfer limitations for the loss of water - depends on the size and number of bubbles -- mechanics are to difficult to worry about for this problem.

10

The constant alpha and the liquid composition of water were easily calculated for all time points,

and thus the equation could be rearranged to solve for the corresponding fraction of HMDA in

the liquid phase. 𝑦iFj𝑦?

= 𝛼𝑥iFj𝑥?

Molecular Weight Distribution A key component of the product stream from the batch process is the molecular weight.

The reactor can be stopped at different times throughout the reaction time to produce the desired

molecular weight. In modeling the molecular weight, the carboxylic groups were treated as the

limiting reactant due to excess HMDA being vented from the system. The resulting model is a

derivation of Flory's molecular weight distribution for A-A/B-B step-growth polymerization.5 In

the following equations r is the ratio of the two monomers in the feed stream, ε is the extent of

reaction with respect to the limiting reactant, 𝑀m is the molecular weight of one unit of the

polymer chain, and MW is the average molecular weight of the polymer. In the third equation

MAA is the mass of a segment of the polymer between sequential amine groups (114), and MCC

is the mass of a segment of polymer between sequential carboxylic groups (112).

𝜀 =𝑉𝐶4 m − 𝑉𝐶4 − 𝑉𝐶HI

𝑉𝐶4 m

𝑟 =𝑉𝐶4 m

𝑉𝐶8 m −2𝜔iFjg 𝜐𝑀iFj

𝑑𝑡om

𝑀m =𝑀88 𝑉𝐶8 m −

2𝜔iFjg 𝜐𝑀iFj

𝑑𝑡om + 𝑀44 𝑉𝐶4 m

𝑉𝐶8 m −2𝜔iFjg 𝜐𝑀iFj

𝑑𝑡om + 𝑉𝐶4 m

𝑀𝑊 =𝑀m 1 + 𝑟1 + 𝑟 − 2𝜀

Energy Balance

Due to the relatively small amount of vapor involved in the process, vapor phase thermal

effects were neglected in the overall energy balance. The energy balance proposed involves four

11

terms with three being heat losses due to the forward progress of the endothermic reaction and

the vaporization of both HMDA and water. The fourth term accounts for the increase in

temperature from the heating jacket. The heat of vaporization for water is time dependent, while

the heat of vaporization of HMDA was considered to be constant over the temperature range of

the reactor.5

𝑑𝑇𝑑𝑡 = −

∆𝐻st'𝜌𝐶=

𝑅; −∆𝐻_iFj ∗ 𝜐iFjF

𝜌𝐶=𝑉−∆𝐻_? ∗ 𝜐?F

𝜌𝐶=𝑉+𝑄vg<o𝜌𝐶=𝑉

∆𝐻_? =7.724𝑇#

𝑇 − 45.15 # ,∆𝐻_iFj = 12.4

𝑘𝑐𝑎𝑙𝑚𝑜𝑙

Description of Process A step-by-step explanation and run-through of the BFD from Figure _ will be explained

further below. There are different cases concerning the polymerization step of the reaction. The

base case and suggested case for this process is 100% use of batch reactors. The first alternative

case utilizes plug flow reactors, while the second alternative case is a combination of 67% batch

reactor production and 33% continuous reactor production.

Initial Mixing of Reactants Equimolar amounts of adipic acid and HMD will be mixed together with water to form

the Nylon 6,6 salt (NH salt). There are three storage tanks holding working capital amounts of

adipic acid, hydrochloric acid and HMD. From these storage tanks, these three compounds will

be transferred to either a batch or continuous reactor for polymerization. In addition to the

storage tanks, process water will also be added through the process water line in the plant. Each

of these four flows will be combined into a holdup tank for the batch reaction processes, while

directly inserted into the plug flow reactor for the continuous process. Since polymerization does

not occur until 440K and water is not being removed from the system, the reactions will not

begin in the holdup tank.5 Another consideration is that the adipic acid must be "molten" before

being added to the other reactants, so a heat exchanger will heat the adipic acid to 450K before

mixing with the other reactants and hydrochloric acid catalyst. Figure 6 shows a close look at the

simple heating of adipic acid.

12

Figure 6. Forming molten adipic acid through use of heat exchanger with steam.

The main inputs and outputs to the system are summarized as follows:

• Input steam: 650 psig, 311°C; Output Water: 650 psig, 190°C • Input Adipic Acid: 25°C, 1 bar, solid; Output Adipic Acid: 180°C, 1 bar, liquid • Heat Duty of Exchanger: 1047.12 MJ/hr • Steam Flow Rate: 500.4 kg/h

Since the adipic acid is a liquid after going through the heat exchanger, it can be pumped

to the holdup tank to be further processed. Each of the four reactant streams will use pumps and

a control system to make sure the flow rates of the reactants are consistent and accurate. This is

important in terms of the amount of water and equimolar concentrations of adipic acid and HMD

as these aspects are what drive the polymerization to occur. Table 5 shows what the flow rates of

the reactants for batch and continuous systems would be.

Table 5. Flow rates of all components for both batch and continuous processes.

Stream Batch Flow Rate (kg/min) Continuous Flow Rate (kg/min) Adipic Acid 46.20 12.32 HMD 36.74 12.32 Water 10.35 36.95 HCl 0.93 - Holdup Tank 141.36 No Holdup Tank Cycle Time 90 min. to Holdup Tank

60 min. to Batch Reactor Assume on one hour basis for flow

rates

Polymerization The next step in the process is polymerization and can either be done in a batch process,

continuous process, or a mixture of batch and continuous systems to obtain the desired capacity

egrulke

Sticky Note

adipic acid is soluble in hot water - this is probably how you would do the process

13

(meaning separate batch and continuous operations at the same plant). Three cases for

polymerization are discussed in further detail in this section. The base case, using all batch

reactors, was modeled in MATLAB, and contains unique, optimized results from other

processes. The continuous processes discussed are based off of designs in ASPEN and the results

of large production of Nylon 6,6 in these settings to present an alternative methodology.

Base (Suggested) Case: All Batch Reactors for polymerization The base case for this process utilizes five, 7,500 liter tanks to accomplish polymerization

of Nylon 6,6. The batch reactors must be purged with nitrogen with a content of less than

0.005% oxygen, since the polymer in the presence of oxygen will degrade during the

polymerization process.6 After the tanks are purged with nitrogen, the mixture of reactants is

then sent into the reactor to begin polymerization. The manipulated inputs needed for the process

were pressure to the tank, initial temperature, heat into the reactor tank, and concentrations of the

reactants. The initial conditions for the reactors are5:

• Concentration of Adipic Acid and HMDA: 6 mol/L • Concentration of Water: 10.9 mol/L • Initial Temperature: 428 K; Initial Volume of Reactants: 4,743 L

The heat input followed the trend in Figure 7a and the pressure and vaporization pressure is

shown in Figure 7b.

a) b) Figure 7. Heat inputs and pressure profiles are depicted for the batch polymerization process.

Using these initial conditions and inputs to the batch reaction process, it was found that a

batch time of 1.8 hours optimized the results of the process. The goals of polymerization are to

obtain concentrations of amine groups, carboxyl groups, and water near 0, to maximize the

14

concentration of the polymer, to maintain a temperature below 610K to not degrade the

chemicals in the process, and to have a low concentration of unreactive stabilized ends. Figure 8

shows the results of the batch polymerization after 1.8 hours, the reaction time.

a) b)

c) d) Figure 8. The results are as follows: a) temperature profile, b) volume profile, c) vent rate profile, d) molecular weight profile.

The important ending results were a temperature of 596K, volume of 3,450 L, and an

average molecular weight of 14,004 g/mol. In the batch reactor, there is leniency in the fact that a

client can demand a product anywhere between an average molecular weight of 10,000 and

14,000, and all that has to change is the time in the reactor. This presents a clear advantage over

the continuous reactors where flow rates will have to change, which will affect other parameters

in the process, which will be described in alternative case #1. The ending temperature remains

less than 610K, which shows that the Nylon polymer will not degrade during the polymerization

process, but also above 537K so that the polymer will be liquid and can be extruded after the

15

polymerization process easily. Further results obtained from MATLAB, including the

concentration profiles of components, are shown in Figure 9.

a) b)

c) d)

e)

Figure 9. The results are as follows: a) amine concentration profile, b) carboxyl concentration profile, c) monomer concentration profile, d) stabilized end concentration profile, e) water concentration profile.

16

The concentrations of amine groups, carboxyl groups, and water all approach 0, while the

concentration of monomer groups ended up around 8 mol/L, with the unreactive stabilized ends

around 0.05 mol/L. The final extent of reaction was 0.935, or 93.5%, showing a very good rate

of polymerization in the process. To achieve these batch results, the batch reactors will need

baffles and a variable speed agitator based off of the viscosity of the liquid. The batch reactor

schematics in Figure 10 show what each batch reactor will look like.

Figure 10: Top and side views of the batch reactor used in the process.

The model for the viscosity of the process for the variable speed agitator to work through

is depicted in Figure 11. The impeller tip speed reaches a maximum of just under 1 RPM to

maintain a turbulent Reynold's Number of 10,000, which should be easily obtainable for the

process.

a)

17

b) Figure 11: Viscosity profile of polymer solution (a) and required impeller tip speed of agitator (b) throughout duration of process.

A typical cycle time (𝑡o) for a batch polymerization process ranges from 5-60 hours, and

is represented as the sum of the times of the four steps below.7

tt=tf+te+tR+tc

tf: Charge feed to reactor and agitate te: Heat to reaction temperature

tR: Carry out reaction tc: Empty and clean reactor

In this case, the time for the batch reactors are 1 hour to charge the feed, 1 hour to heat

the reactor to 428K, 1.8 hours to carry out the reaction, and 2 hours to empty and clean the

reactor (1 hour to empty, 1 hour to clean). This will allow each batch reactor to run four times

per day with a leniency of 48 minutes per day to account for any complications, with a cycle

time of 5.8 hours per batch. Assuming four batches per day per reactor, an operating schedule of

330 days a year, and about 6,351 kg of Nylon 6,6 produced per batch, the maximum amount of

Nylon 6,6 that can be produced is 92.23 million pounds, which exceeds the target production by

7.23 million pounds. This shows that there is leeway of running behind schedule of 1,138 total

batches for the year, or 57 days of operating all five reactors, and still creating the demand of

85,000,000 pounds per year of Nylon 6,6. In addition to this cushion, two extra batch reactors

will be purchased to assure demand can be met by the production plant.

18

If the demand were to force production to slip to 67% of normal capacity, then only three

to four of the five batch reactors would run at a time to meet this need. This would require less

operators to be available and would help reduce costs in the case that demand were to fall

throughout any part of the year.

Alternative Case #1: All Continuous Reactors The continuous system was modeled in ASPEN PLUS instead of MATLAB due to the

number of variables that would have to be manipulated. It was more feasible and accurate to

model the continuous process with a PFR and CSTR in ASPEN PLUS, as these two systems

would require two separate sets of ODEs in MATLAB. The inputs, outputs, specifications, and

ASPEN model will be described further throughout this section.

The schematic produced in ASPEN is shown below with the feed mixture being sent

through a PFR and a CSTR in series. The PFR acts to begin the polymerization process, and the

resulting mixture is then sent to a CSTR to complete the polymerization and evaporate off excess

water to increase purity.

Figure 12. ASPEN schematic for proposed continuous process involving use of a PFR and a CSTR.

There were a total of 8 components input into ASPEN to model the polycondensation

reaction. End (-E) and repeat (-R) units of both HMDA and adipic acid were added to further the

precision of the model. These components were specified as segments as they are part of the

polymer chain.

19

Figure 13. List of components input into the ASPEN simulation.

For this model, 12 reactions were input into ASPEN.8 The reactions with the most

emphasis are reactions 1 and 9, and they represent the reversible condensation reaction to form a

finished unit of Nylon 6,6. The rest of the reactions listed form repeat units of polymer that can

then further react to produce longer chains.

Figure 14. List of possible reactions for ASPEN model.

Input specifications for the PFR are shown below. The entering mass flowrate was set so

that the flowrate of Nylon 6,6 remains below 1200 kg/hr, so it can be sent to the extruder for

further processing.

Figure 15. PFR feed specifications; Total flow rate of 3695 kg/hr with 60wt% water.

20

Figure 16. Specifications of PFR; Isothermal operation, L = 150m, D = 0.1m.

The product stream from the PFR is subsequently sent to a CSTR with operating

conditions shown below. The temperature was set to 605K to evaporate off all the excess water,

while not leading to decomposition of the Nylon 6,6 polymer.

21

Figure 17. Specifications of CSTR; Pressure = 5 atm, Temperature = 605K.

Figure 18. Specification of phases of two product streams produced from CSTR.

The molecular weight profile of the polymer down the length of the PFR is shown below.

The mixture can be extracted from the PFR and sent to the CSTR at any point along the PFR to

have control over the resulting molecular weight of the polymer produced.

Figure 19. Molecular weight distribution down the length of the PFR.

The flowrates and fractions of all streams involved in the process are shown below. The

PFR attains a 32.37% by mass solution of Nylon 6,6, and the CSTR further refines this stream to

22

99.50% by mass. Nearly all the reactants were used up, which is evident by the mass fractions of

both reactants being approximately 0 in both product streams.

Figure 20. Stream table output from ASPEN simulation.

In case demand dictated to produce at 67% the normal capacity, three to four of the lines

would run at a single time, instead of the normal five lines of continuous processing. This would

require less operators to be available and would help reduce costs in the case that demand was to

fall throughout any part of the year.

Alternative Case #2: 67% batch; 33% continuous This case utilizes both the batch process in the base case and the continuous process in

the first alternative case. To meet the 85,000,000 pounds per year, three batch reactor lines

would run at 340 days a year, while 2 continuous processing lines would run 315 days a year,

which would provide the necessary requirements to meet the expected demand. The reason this

was presented as an alternative was the ease of producing at 67% capacity by just shutting down

the continuous processing lines and allowing the batch reactors to run. This method also allows a

variation in products as the profiles of Nylon 6,6 are slightly different, which can be a benefit if

selling to multiple markets, and damaging if selling to just a few customers. The pros and cons

would need to be weighed based off the market that is being targeted by the company. One note

to mention is that operators would have to be cross-trained to run both the batch and continuous

polymerization processes in case there were any complications in labor availability, which would

add to the cost of training operators.

23

Extrusion #1, Chip Formation, and Evaporation of Cooling Water After the polymerization process, the melted Nylon 6,6 is removed from the reactors. For

the batch process, pure nitrogen is used to pressurize the reactor to evacuate the polymer from

the reactor that forms polymer "ribbons" and these "ribbons" are placed into another tank.9

Cooling water is added to the polymer immediately to solidify the polymer and the

polymer/water mix is cut into chips and then heated to evaporate the water from the polymer

chips.6 The only difference in the continuous process is that the plug flow reactor and the

reactant pumps will force the polymer solution into tanks and then the process will continue very

similarly, just in different amounts of polymer. Once the chips are formed, they are stored in

hoppers and drums to continue to the next extrusion process.

The specifics of this process are in the amount of cooling water needed for the amount of

polymer, and how the water will evaporate, and at what temperature, from the polymer chips, in

addition to the times of the process. The ribbons of molten polymer being extruded through holes

of an extruder will be sprayed with cooling water at a rate of 0.1 kg of cooling water to 1 kg of

polymer. This results in 635.2 kg of cooling water needed per batch to solidify the polymer

ribbons. These solid ribbons are then sent to a cutting machine and exposed to a temperature of

150°C to evaporate the water. The chip cutter creates 3-4mm thick chips of Nylon 6,6 and can

run at a rate of 10 meters of ribbon per minute, which equates to around 60 kg/min, assuming 60

ribbons (about 1 kg per 10m of ribbon) are created from the extruder, as is shown in Figure 21.

Figure 21. A picture of what the ribbons from the extruder will look like is shown from an extruder with 60 holes to form 60 ribbons.10

The subsequent chips from the cutting machine are exposed to the high temperature

(~180°C) for around 30 minutes to ensure water is completely removed from the system. The

cycle time for this step for the batch process is 2.44 hours total. The chips are then stored for the

second extrusion process. There will be an extruder and chip cutter in this process for each of the

reactors, whether it be the continuous, batch, or mixed process. The resulting chips are then

24

stored and combined from all the reactors, so that the second extrusion process can occur,

starting with the Nylon in chip form.

Extrusion #2 – Melting and Homogenization and Filtration After the chips are dried and placed in their storage containers, a second extrusion

process must take place to melt the chips and homogenize the liquid polymer. The type of

extruder used is a twin-screw extruder that melts the feed, mixes to a uniform temperature and

pressure, uses a decompression zone, and then a second metering area to re-pressurize the

polymer liquid. The extruder utilized is a TSE-130, that will output 1,200 kg per hour of

polymer.11 Therefore, 6,351 kg of polymer per batch will take 5.30 hours to complete the

process. To melt the polymer chips, the extruder must maintain a temperature greater than

264°C, so the extruder will operate at 300°C to ensure complete liquification and homogeneity,

as this is the recommended temperature from multiple research sources.6,11 After the second

extrusion to re-liquefy the polymer, the melt must be filtered and sent to a spinneret system. This

must be done at the same rate as the extruder to prevent buildup of polymer and thus, will take

the same amount of time as the extruder.

The main consideration other than timing and equipment specifications is the type of

additives that will be inserted into the liquid polymer to determine the final properties of the

Nylon 6,6 fiber. Certain additives will be discussed in the other important considerations section

that customers can choose for the products that are desired. Since Nylon 6,6 is used in many

fields, there are many different routes that a Nylon 6,6 manufacturing company can go. In

addition to variability in products, there can be variability between lines where five different

Nylon products can be manufactured at one time due to there being five different operating lines.

Spinneret System and Stretching for Final Product Properties The polymer is then sent to a spinneret system where the final product will be created.

The specific spinneret system utilized will be a JWPCF4T-15/9.5, a common piece of equipment

for melt spinning.12 The liquid polymer is solidified using cross-flow air and spun around a "roll"

to form the fiber. After the fiber is formed, the fibers can be stretched to form the wire

dimensions that are needed. Five different parameters that need to be researched to develop the

correct fiber specifications are:6,12

• Mass output (recommended 1200 kg/h)

25

• Winding Speed (recommended 2000 m/h) • Spin-Draw Ratio (recommended 20) • Draw Ratio (recommended 3) • Draw Temperature (recommended 300 °C)

The final output product should look like a variation of Figure 22.

Figure 22. Typical final product obtained from spinneret system.12

Cycle Time Summary Table 6. Times for each process step and total cycle time for both batch and continuous.

Process Step Batch Time for 1 batch (hours) Continuous Time (hours) Initial Mixing 2.50 - Polymerization 5.80 5.45 Extrusion 1 2.44 2.44 Extrusion 2/Filtration 5.30 5.30 Spinneret/Stretching 5.30 5.30 Total 21.34 18.49

Control Systems Summary In order to produce a marketable product of Nylon 6,6 it is paramount to monitor and

control the process through multiple control systems. The flowrate of reactants to the reactors,

temperature and pressure of the reactors, and the product quality will all be measured and

controlled as needed. Flow control valves will be utilized to monitor the flowrate of the reactants

being charged to the reactors. The control valves will provide feedback control the upstream

pumps to ensure proper stoichiometric mixing of reactants. A hold-up tank is utilized as a "back-

up" and should assure good control.

26

One of the most common disturbances that will be seen in the reactor deals with overall

heat transfer from the heating jacket.13 To deal with this, the temperature of the reactor will be

measured through reliable equipment and controlled by a transmitter and controller. The

temperature controller will act as a feed-back loop, and will manipulate the flowrate of the

heating oil accordingly. Temperature measurements are easy to obtain within the reactor, but the

values may not be very representative due to the size of the reactor. Although a design

assumption stated before was that there are no spatial variations, it is highly unlikely that there is

not a temperature gradient within the reacting mixture. To test for temperature gradients resistant

temperature detectors (RTD's) will be used at different heights in the reactor.14 Due to the

possibility for a temperature gradient, the pressure of the reactor will also be controlled.

The pressure of the system will be measured through piezo resistive pressure controllers.

These sensors will detect a strain due to the pressure of the liquid mixture above and will

transmit the measured strain to an electrical signal which will be sent to the corresponding

controller.15 The controller will send signal to the vent control valve to maintain the pressure

according the pressure profile.

Small deviations could purposely be introduced into the system to test the control

systems. An example deviation would be to increase the water composition in the charge to the

reactor. This will cause the reaction to be forced slightly in the reverse direction resulting in the

liquid phase and in turn being vaporized. The pressure of the system would increase due to the

increased amount of HMDA and water in the vapor phase. This increase in pressure should

create a larger signal sent to the vent control valve which should lead to a larger vent rate.

Quality Control and AssuranceThe final fiber produced from the spinneret system will be analyzed using a near-infrared

spectroscopy (NIRS) method. NIRS will provide insight into the amounts of amine and

carboxylic groups present in the polymer.16 Based on the results from the NIRS, a small amount

of additional HMDA or adipic acid could be added to the process late in the reaction to balance

out the amine and carboxylic groups. This aspect of quality control is important if additives are

to be used in the final product, because the additives attach to the functional groups.

27

Plant LayoutThe plant layout for five batch reactor lines is depicted below in Figure 23 as the batch

process line is the base case.

Figure 23. Overall plant layout for base case.

Utility Requirements For the batch reactor process, the following utility requirements are needed:

• Electricity for pumping flow rates • Electricity and steam to heat adipic acid to "molten" • Heated oil to heat up the reactor (treated as utility)17 • Cooling water for solidification of the polymer • Electricity for extruders, chip cutters, and the spinneret systems

Tables 7 through 11 show how much of each utility is needed for the process at 100% capacity

and at 67% capacity for the whole year depicting the high and low scenarios.

28

Table 7. Utility requirement of batch process pumps at full and 67% capacity.

Pump Type Flow (kg/h) Power (kW) Power/yr (kWh) 67% capacity power/yr (kWh)

Water 621 0.15 1356 909 HMDA 2204.4 0.53 4814 3225 AA 2772 0.66 6054 4056 HCl 55.8 0.01 122 82 Hold Tank 8481.6 2.03 12348 8273 Cooling Water 120 0.03 925 620 Total 25619 17165 Table 8. Utility requirement of heating adipic acid at full and 67% capacity.

Heating Adipic Acid

Steam/batch (kg)

Steam/yr (kg)

67% capacity steam/yr (kg)

Power/batch (kWh)

Power/yr (kWh)

67% capacity power/yr (kWh)

750.6 4565900 3059153 0.44 2656 1780 Table 9. Utility requirement of thermal fluid use at full and 67% capacity.

Heated Thermal Fluid Oil Input Amount of Heat per batch (kJ)

Cp of thermal oil (kJ/kg*K)17

Amount of oil per batch (kg)

Needed Oil/yr (kg)

67% capacity Needed Oil/yr (kg)

597456 1.8 3951.43 59271.46 39711.88

Electricity (kW) Electricity/year (kWh)

67% capacity Needed Electricity/yr (kWh)

165.96 1009535 676389 Table 10. Utility requirement of cooling water at full and 67% capacity.

Cooling Water Percent of CW to Nylon CW/year (kg) 67% capacity CW/year (kg) 10% 3863636 2588636 Table 11. Utility requirement of electricity for downstream process equipment at full and 67% capacity.

Other Electricity Costs

Equipment Power (kW) for one batch

Power/year for one

Number of Equip. Used

Total Power/yr (kWh)

67% capacity power/yr (kWh)

Extruders10 205 1247015 10 12470150 8355001 Chip Cutter18 60 364980 5 1824900 1222683 Spinneret System12 100 608300 5 3041500 2037805 Total 17336550 11615489

29

For the continuous reactor process in alternative case 1, the same utility requirements are

needed as for the batch reaction process, just in different amounts except for Tables 12 and 13,

where the other electricity requirements and steam requirements are the same.

Table 12. Utility requirement of continuous process pumps at full and 67% capacity.

Pump Type Flow (kg/h) Power (kW) Power/yr (kWh) 67% capacity power/yr (kWh)

Water 2217 0.53 17083 11446 HMDA 739.2 0.18 5696 3816 AA 739.2 0.18 5696 3816 Mixer 1200 0.29 9247 6195 Cooling Water 120 0.03 925 620 Total 38646 25893 Table 13. Utility requirement of continuous process reactors at full and 67% capacity.

Utilities from ASPEN to heat up and run reactor Power (kW) for

one batch Power/year for

one Number of

Equip. Total Power/yr 67% capacity

power/yr (kWh) 134.38 2163314 5 108165712 7247103

The alternative case #2 is a combination of the batch and continuous utilities. For the

total utilities in one year, the batch utilities in the 67% column are used and 33% of the total

utilities of the continuous process solution would be utilized. At 67% capacity for alternative

case #2, the utilities utilized would only be the 67% capacity of the batch utilities depicted in

tables 7 through 11.

Equipment List and Unit Descriptions Table 14. The specifications for each piece of equipment utilized in the process. Batch Reactor Equipment Specifications

Reactant Storage Tanks

• Spherical • Carbon Steel • 1 – 120,000 Gallon Tank • 1 – 94,000 Gallon Tank • 1 – 10,000 Gallon Tank

Pumps • Power and flow rates are depicted in the utility requirement sections

Batch Reactor • 7,500 L • Stainless-steel • Variable Speed Agitator

30

• Thermal Fluid Jacket – Variable Temperature • Diameter: 1.85m • Height: 2.78m

Extruder TSE-13010

• 125 hp • Screw Speed: 42 RPM • Total Power: 205kW • 950 – 1200 kg/hr • Length: 6.38m • Width: 2.26m • Height: 2.70m • Weight: 9500 kg

Product Storage Tanks / Warehouse

• 5 – 12m x 12m x 12m storage "houses" • Steel Walls and Ceiling

Holding Tank

• Diameter: 1.85m • Height: 2.78m • Stainless-steel • 7,500 L • Heated Jacket: Constant 428K

Chip Cutter18

• 10m Nylon ribbon / minute • 60 kg Nylon ribbon / minute • Creates 3-4mm sized chips • 180°C • Feed of 60 ribbons of Nylon

Spinneret System12

• Wall Thickness: 0.03m • Pressure Tolerance: Up to 31 MPa • Filtration Area: 2m x 9.5m • Mass output (recommended 1200 kg/h) • Winding Speed (recommended 2000 m/h) • Spin-Draw Ratio (recommended 20) • Draw Ratio (recommended 3) • Draw Temperature (recommended 300 °C)

Heat Exchanger (Dowtherm)17

• ~ 5 m2 • U:341 W/m2K • Cross Flow Heat Exchanger • Fixed Head

Heat Exchanger (AA)

• 3.29 m2 • U: 600 W/m2K • Cross Flow Heat Exchanger • Fixed Head • Steam: 500.4 kg/h; 311°C; 650 psig

Cont. Equipment not listed Specifications

PFRs • Length: 150m • Diameter: 0.1m

31

• Temperature: 550K • Pressure In: 10 atm • Pressure Out: 5 atm

CSTRs • Temperature: 605K • Pressure: 5 atm • Volume: 7,500 L

Mixer

• 7,500 L • Cylindrical • Diameter: 1.85m • Length: 2.78m • Stainless-Steel

Equipment Specification Sheets All the specifications for the batch reactors, PFRs, CSTRs, and storage tanks are

described in the previous sections of process description and equipment specifications. Extruders: Table 15. Specification Table for extruder used in the process (see TSE-130).10

32

Chip Cutters:

Figure 24. Specification Table for chip cutter used in the process.18 Spinneret Systems: Table 16. Specification Table for spinneret used in the process (see JWPCF4T - 15/9.5).12

All other equipment specifications needed for purchasing of equipment can be found in

the previous sections of the report.

33

Equipment Cost Summary

The equipment costs for the base case and both alternative cases are shown in Tables 17

through 19. The amount of equipment needed already includes the spares, and cost distributions

and totals are depicted. Table 17. Individual equipment costs and total purchased equipment cost for base case.

Batch Equipment Costs

Equipment Number Needed

Spares

$/piece Total Price ($)

Batch Reactors7 7 2 174809 1223666 Storage Tank 1 (HMDA)19 1 0 272341 272341 Storage Tank 2 (AA)19 1 0 227046 227046 Storage Tank 3 (HCl)19 1 0 30676 30676 Extruder TSE-13020 12 2 162690 1952280 Product Storage 5 0 195587 977935 Pumps 35 5 4837 169307 Hold Tank7 7 2 22797 159579 Chip Cutter20 6 1 93262 559574 Spinneret System20 6 1 362788 2176731 Heat Exchanger (for Dowtherm) 6 1 4500 27000 Heat Exchanger (AA) 6 1 5360 32160 Total 7808294 Table 18. Individual equipment costs and total purchased equipment cost for alternative case 1.

Continuous Equipment Costs

Equipment Number Needed Spares $/piece Total Price ($)

PFR 7 2 125676 879732 CSTR 7 2 131232 918624 Storage Tank 1 (HMDA) 1 0 272341 272341 Storage Tank 2 (AA) 1 0 227046 227046 Extruder TSE-130 12 2 162690 1952280 Product Storage 5 0 195587 977935 Pumps 35 5 4837 169307 Chip Cutter 6 1 93262 559574 Spinneret System 6 1 362788 2176731 Heat Exchanger (for Dowtherm) 6 1 4500 27000 Heat Exchanger (AA) 6 1 5360 32160 Total 8192730

34

Table 19. Individual equipment costs and total purchased equipment cost for alternative case 2. 67% Batch, 33% Continuous Equipment Costs

Equipment Number Needed Spares $/piece Total Price ($)

PFR 3 1 125676 377028 CSTR 3 1 131232 393696 Batch Reactors 5 2 174809 874045 Storage Tank 1 (HMDA) B 1 0 204120 204120 Storage Tank 2 (AA) B 1 0 170172 170172 Storage Tank 3 (HCl) B 1 0 30676 30676 Storage Tank 1 (HMDA) C 1 0 122586 122586 Storage Tank 2 (AA) C 1 0 102198 102198 Extruder TSE-130 12 2 162690 1952280 Product Storage 5 0 195587 977935 Pumps 35 5 4837 169307 Chip Cutter 6 1 93262 559574 Spinneret System 6 1 362788 2176731 Heat Exchanger (for Dowtherm) 6 1 4500 27000 Heat Exchanger (AA) 6 1 5360 32160 Total 8169508

Fixed Capital Investment Summary The main items under FCI were purchased equipment costs (shown in equipment cost

summary), buildings, and land. An estimated cost to construct a building was $40 per square

foot.21 Finding similar plants to have 300,000 ft2 of manufacturing space and 125,000 ft2 of

office space, led to a building cost of $17,000,000. In addition to a building, land of 140 acres

was found in Calvert City, Kentucky that was worth $4.2 million and appeared to be easily

developable. All the other indirect and direct costs were taken as percentages of the purchased

equipment capital per year from an economic template. The results are shown in Table 20. There

was a buffered cost instituted in the FCI for control valves in instrumentation and controls and

other costs associated with minor equipment and other unforeseen costs in service facilities.

35

Table 20. Comparison of fixed capital investment for all cases. Batch Continuous Mixed Direct Costs equipment + installation purchased equipment cost (PEC) $7,808,294 $8,192,730 $8,169,508 installation $4,276,874 $4,488,314 $4,475,541 instrumentation & controls $466,568 $489,634 $488,241 piping $777,613 $816,057 $813,735 electrical, installed $777,613 $816,057 $813,735 buildings $17,000,000 $17,000,000 $17,000,000 service facilities $7,776,134 $8,160,570 $8,137,348 land $4,200,000 $4,200,000 $4,200,000 $43,050,937 $44,131,202 $44,065,948 Indirect costs engineering/supervision $150,000 $150,000 $150,000 construction expense $2,583,056 $2,647,872 $2,643,957 contingency $2,409,684 $2,469,951 $2,466,311 Fixed capital investment (FCI) $48,225,837 $48,431,185 $49,358,376

Manufacturing Costs Raw Material Costs The cost found for each raw material is as follows:9,19,22

• Adipic Acid: $1.50 / kg • HMDA: $2.50 / kg • Process Water: $0.75 / 1000 gallons • HCl: $0.17 / kg • Nitrogen: $0.90 / 100ft3

Table 21. Raw material costs for 67% and 100% capacity of operation. Worst Case: 67% capacity all year Best Case: 100% capacity all year Compound Amount Total Price ($) Amount Total Price ($) Adipic Acid 16,715,646 kg 25,073,469 24,948,725 kg 37,423,088 HMDA 13,291,810 kg 33,229,526 19,838,523 kg 49,596,308 Nitrogen 10,794,671 ft3 97,152 16,111,449 ft3 145,003 HCl 300,074 kg 51,013 447,872 kg 76,138 Water 987,959 Gal 741 1,474,565 Gal 1,105 Total $58,451,900 / yr $87,241,641 / yr

36

Utility Costs The cost found for each raw material is as follows:17,19

• Electricity: $0.06 / kWh • Thermal Oil: $14.79 / kg • Cooling Water: $0.02 / m3 • Steam: $6.60 / 1000 kg

Table 22. Comparison of annual utility cost for all cases operating at both 67% and 100% capacity.

Batch Continuous Mixed

Type of Utility

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($) Pump Electricity 1030 1537 1554 2319 1203 1795

Steam + HE Elec. 20297 30294 20297 30294 20297 30294

Heat/Run Reactor 627922 937197 434826 648994 564200 842090

Cooling Water 52 77 52 77 52 77

Other Electricity 696929 1040193 696929 1040193 696929 1040193

Total cost per year $1346230 $2009298 $1153658 $1721877 $1282681 $1914450

Other Major Manufacturing Costs Table 23. Other manufacturing costs for all cases operating at both 67% and 100% capacity.


Type of Cost

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($) Operating

Labor 1,772,152 2,658,228 2,658,228 3,987,342 2,126,582 3,189,873

Maintenance 1,204,842 1,204,842 1,234,976 1,234,976 1,233,155 1,233,155 R&D 1,598,695 2,269,550 1,620,009 2,302,805 1,609,760 2,285,394

Selling, General, and Administrative (SG&A) CostsOther major costs that go into the bottom line are costs that are not associated with

manufacturing, but still are important to the economics of the company. These results are

depicted in Table 24.

37

Table 24. SG&A costs for all cases operating at 67% and 100% capacity.


Type of Cost

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($)

67% Capacity

($)

100% Capacity

($) Admin. 1,598,695 2,269,550 1,620,009 2,302,805 1,609,760 2,285,394

Dist. And Selling 1,598,695 2,269,550 1,620,009 2,302,805 1,609,760 2,285,394

Taxes 23,131,474 34,043,252 23,452,091 34,542,073 23,293,167 34,280,905

Economic Analysis Economic assumptions19

• Bulk prices of HMDA and Adipic Acid are correct • Economic Template utilized uses accurate estimates • Utility Costs found from Seider are accurate • Equipment costs gathered from resources, APSEN, and CHEMCAD are correct • Product prices remain reasonably stable over the time period examined • Straight-Line Depreciation • Equipment is useful for an average lifespan of 10 years • Demand stays relatively constant (shifting demand talked about in other considerations)

Using all of the information stated in previous sections, and the economic template and

tables shown in Appendix C, cash flow plots for the next 20 years were able to be constructed.

The "best-case" and "worst-case" scenarios depict what the cash flow analysis would be at

85,000,000 pounds of Nylon production and at 67% of that capacity respectively. The revenue

for each case at a product price of $1.45 per pound of Nylon fiber is:23,24

• Revenue at 100% capacity = 85,000,000 x $1.86 = $158,100,000 • Revenue at 67% capacity = 85,000,000 x 0.67 x $1.86 = $105,927,000

Figures 25 through 27 show the results of the processes described.

38

Batch Cash Flow Plots

a)

b)

Figure 25. Cash flow analysis over 20 years for a) batch best case and b) batch worst case.

39

Continuous Cash Flow Plots a)

b)

Figure 26. Cash flow analysis over 20 years for a) continuous best case and b) continuous worst case.

40

Alternative Case #2 Cash Flow Plots a)

b)

Figure 27. Cash flow analysis over 20 years for a) mixed best case and b) mixed worst case.

41

Table 25. Summary of results obtained from cash flow analyses. Cash Flow Type Breakthrough

Year Total Gains Total Investment 20 Year ROI

Batch Best 5 $153, 913,417 $56,034,131 274.7% Batch Worst 9 $56,694,490 $56,034,131 101.2% Cont. Best 7 $109,476,946 $57,623,915 190.0% Cont. Worst 14 $27,702,373 $57,623,915 48.1% Alt. Case 2 Best 6 $132,184,305 $57,527,884 229.8% Alt. Case 2 Worst 12 $41,548,579 $57,527,884 72.2%

Seeing the results of the plots and the ending return-on-investment, the best option

economically is the base case of using all batch reactors for polymerization. The breakthrough

year is sooner for the best case and is able to take a hit in demand much more robustly than the

other two cases as is seen in Table 25.

Using the batch best case as a control, sensitivity analyses can be performed by changing

variables such as selling price and raw material prices to see how the economics of the company

will change with minor differences in inputs. Three sensitivity analyses will be performed to

show what will happen to the overall economics in certain circumstances.

1. Increase in price of HMDA by $0.15 / kg and by $0.25 / kg

Figure 28. Deviation caused in cash flow for batch best case if price of HMDA is increased by $0.15/kg (a) and by $0.25/kg (b).

42

2. Decrease in selling price by $0.10 / lb

Figure 29. Deviation caused in cash flow for batch best case if selling price of Nylon 6,6 is decreased by $0.10/lb.

3. Increase in selling price by $0.10 / lb

Figure 30. Deviation caused in cash flow for batch best case if selling price of Nylon 6,6 is increased by $0.10/lb.

The three sensitivity analyses show some troubles in the process. The economics show it

to be very volatile in the selling price of Nylon 6,6 and buying price of raw materials. This is a

concern for the process as the breakeven point is greatly affected by minor changes of the prices

in the negative direction, while the positive change shifts the breakeven point slightly. Demand

and commercialization will be discussed in the other considerations section, but the market will

largely dictate whether this process is profitable or even if it should be pursued.

43

Safety, Health, and Environmental Considerations Safety and Health Affects

In order to ensure that process runs safely a considerable amount of information must be

obtained for all of the hazardous reactants used in the process. Adipic acid and HMDA are the

two monomers used in the production of Nylon 6,6, so key properties of these components will

be analyzed. Training must be given with regards to the handling of these chemicals including

the use of the proper personal protective equipment (PPE). All workers must be well informed

and should consult SDS sheets for further information.

Adipic acid contains the carboxylic groups necessary for the polycondensation reaction to

form Nylon 6,6. Adipic acid is odorless, an irritant to skin and especially the eyes, and is

hazardous if ingested or inhaled.25 Due to the potential for severe eye damage, it is paramount to

wear proper eye protection when handling. The NFPA diamond for adipic acid is shown below

in Figure 31.

Figure 31. NFPA diamond for adipic acid.

HMDA contains the amine groups necessary for the reaction to proceed. HMDA has a

weak fish-like odor, is an irritant to the eyes, corrosive to skin, and hazardous if ingested or

inhaled.26 HMDA has also been found to be harmful to aquatic organisms, so proper disposal of

excess HMDA must follow strict regulations. The NFPA diamond for HMDA is shown below in

Figure 32.

Figure 32. NFPA diamond for HMDA.

44

Table 26. Key characteristics for both adipic acid and HMDA.25,26 Adipic Acid HMDA UEL 9.4% 6.3% LEL 1.1% 0.7% LD50 1900 mg/kg 750 mg/kg Auto-ignition Temperature 422 ºC 390-420 ºC TLV-TWA 5 mg/m3 2.3 mg/m3 Inherently Safer Design

The four key attributes in produced an inherently safer design are minimize, substitute,

moderate, and simplify.27 The best way to control hazards is to minimize, and ideally eliminate,

their potential. Substitution can also be used reduce the risk for hazards with examples being

using less toxic solvents and using water as thermal fluid rather than hot oil. It is important to

moderate the process by limiting temperatures and pressures of streams and process units.

Reactors should be operated under conditions where a runaway reaction is not possible. The

fourth component of inherently safer design, simplify, can be done by labeling all process

equipment to easily differentiate between blocks.

There are always ways to improve industrial processes and to make them safer. One way

to minimize the potential for hazard in this design is to reduce the amount of raw materials stored

on hand at any given time. However, this may not be feasible due to the high demand for the

reactants to keep the process running. So rather than reducing the amount of working capital,

more sophisticated and integrated control systems could be implemented to ensure that

hazardous, intermediate chemicals are kept to a minimum. No substitution methods can be

feasibly applied due to the nature of the process. The reactants are very specific to the reaction,

and water is already being used as the solvent. Heating oil must be used in the heating jacket to

the batch reactor because superheated steam cannot achieve the required heat transfer.

Environmental AffectsThe major compounds to consider in terms of environmental affects are the two

monomers, adipic acid and HMDA, and the final fiber product of Nylon 6,6. Starting with an

exposure of the monomers to the environment, HMDA is readily biodegradable and is not

considered bioaccumulative as the log of its Kow is 0.4.26 If ingested by aquatic invertebrates, it

can be harmful to their health systems, but shows no adverse effects on fish or wildlife. It is not

considered a danger to the environment due to its lack of bioaccumulative ability. Effluents with

45

HMDA should be directed to a waste water treatment plant or incinerated to prevent exposure to

the environment. The use of a carbon filter can help combat the vent from the batch reactor.

Adipic acid is also readily biodegradable and is not considered bioaccumulative as the

log of its Kow is 0.09.25 Just like HMDA, adipic acid is harmful to aquatic invertebrates and not

harmful for fish, but the difference lies in its ability to affect water wildlife such as algae.

However, since adipic acid is largely water soluble, it has a very low potential to be volatile and

is not considered a risk to the environment. Gas emissions are not expected since it has a high

boiling point and does not vaporize in the process. Adipic acid is not considered persistent in the

environment, and thus should be relatively easy to handle environmental impacts.

Nylon 6,6 on the other hand is not readily biodegradable. Since it is usually in its solid

state though, it should not accumulate in any biological organisms to create adverse effects. If it

is prevalent in an aquatic environment, fish and invertebrates are prone to toxic effects from

Nylon 6,6.28 Therefore, discharge into the environment must be avoided and should not be

placed in any waterway systems.

HAZOP on Base Case: Batch Reactor System Table 27. HAZOP analysis for batch reactor system. Item Study Node Process

Parameters Deviations

(guidewords) Possible Causes

Possible consequences

Action required

1.1 Storage Tank to HE Adipic Acid (AA1)

Flow High Pump Malfunction Control Valve Failure

Adipic Acid is not heated too high enough temperature Clogging of Pipelines (solids) Too much AA will reach pipeline or buildup around control valve

Control Valve Close Replacement Pumps on Hand Maintenance Check on Pipes

1.2 Storage Tank to HE Adipic Acid (AA1)

Flow Low Pump Malfunction Control Valve Failure Leak in Pipeline

Adipic Acid is heated too high Energy added is too high Not enough AA will reach the holdup tank for the reaction

Control Valve Close Maintenance Checks on Pipes Replacement Pumps on Hand

1.3 HE to Holdup Tank Adipic

Acid (MOLTENAA)


Too much AA will reach pipeline or buildup around control valve Holdup Tank

Control Valve Close Maintenance check on pumps and pipes

46

compound ratios will be off for process

Replacement Pumps and Pipes

1.4 HE to Holdup Tank Adipic

Acid (MOLTENAA)


Not enough AA will reach pipeline or buildup around control valve Holdup Tank compound ratios will be off for process

Control Valve Close Maintenance check on pumps and pipes Replacement Pumps and Pipes

2.1 Storage Tank to Hold-up

Tank HMDA (HMDA2)


Too much HMDA will reach pipeline or buildup around control valve Holdup Tank compound ratios will be off for process


2.2 Storage Tank to Hold-up

Tank HMDA (HMDA2)


Not enough HMDA will reach pipeline or buildup around control valve Holdup Tank compound ratios will be off for process


3.1 Storage Tank to Hold-up Tank HCl

(HCl2)


Too much HCl will reach pipeline or buildup around control valve May speed up reaction too quick Holdup Tank compound ratios will be off for process


3.2 Storage Tank to Hold-up Tank HCl

(HCl2)


Not enough HCl will reach pipeline or buildup around control valve May not be enough catalyst for runtime parameters Holdup Tank compound ratios will be off for process


4.1 Water to Hold-up Tank Water (WATERCON)


Too much water will reach pipeline or buildup around control valve Holdup Tank compound ratios will be off for


47

process 4.2 Water to Hold-

up Tank Water (WATERCON)


Not enough water will reach pipeline or buildup around control valve Holdup Tank compound ratios will be off for process


5.1 Hold-up Tank to Batch Reactor

(FEED2RXR)


Throw off process times Delays schedule


5.2 Hold-up Tank to Batch Reactor

(FEED2RXR)


Breaking of Pumps Throw off process times Pipe degradation


6.1 Batch Reactor (BATCHRXR)

Temperature High Too much heat input in heated jacket (malfunction in heating jacket controller) Thermal fluid heated too high

Degradation of Product MW decrease

Control Valve Close on heated jacket Operators check T regularly Regular Maintenance Replacement Jacket Alternatives


Temperature Low Not enough heat input in heated jacket (malfunction in heating jacket controller) Thermal fluid not heated enough

Reaction does not proceed to completion

Control Valve Close on heated jacket Operators check T regularly Regular Maintenance Replacement Jacket Alternatives


Pressure High Failure to Vent Properly Reactor Malfunction Too much liquid charged

Rupture of Tank Process Disruptions Unsafe operating conditions

Relief Valve Open Gauges to check P regularly Regular Maintenance


Pressure Low Vent Rate is too high Reactor Malfunction Not enough liquid charged

Reaction does not proceed to completion Degradation of Polymer


48


Time High Operator Error Timing Device Malfunction Reaction Heating not accurately depicted

Degradation of Product MW decrease Delay of Schedule Too much heat input

Accurate systems in place Timing Device Backups Regular Maintenance


Time Low Operator Error Timing Device Malfunction Reaction Heating not accurately depicted

Reaction will not proceed to completion Product will not meet specifications Not enough heat input

Accurate systems in place Timing Device Backups Regular Maintenance

7.1 Batch Reactor to Extruder 1

(S2)

Pressure High Nitrogen Input too high Control Valve Failure

Flow of product to extruder too high for extruder capabilities Extruder Malfunction Product Deformation


7.2 Batch Reactor to Extruder 1

(S2)

Pressure Low Leak Nitrogen Input too low Control Valve Failure

Flow of product to extruder too high for extruder capabilities Schedule Delays


8.1 Cooling Water to Extruder 1 (CWCONT)

Flow High Control Valve Failure

Water ends up in the product Degradation of Product

Relief Valve Open Extra cooling water on hand Regular Maintenance

8.2 Cooling Water to Extruder 1 (CWCONT)

Flow Low Leak Control Valve Failure

Product does not solidify Storage of product becomes hard to maintain

Relief Valve Open Extra cooling water on hand Regular Maintenance

9.1 Extruder 1 (EXTRUDER)

Flow High Extruder Malfunction High pressure in tank

Product not extruded properly Warped product ribbons Chip cutting issues

Control Valve Close Maintenance check on extruder

9.2 Extruder 1 (EXTRUDER)

Electrical Shut-down Power Outage Generator Malfunction Surges (Electrical Spikes)

Schedule Delays Product Waste

Backup Generators Surge Protectors No exposed wires

10.1 Nylon to Chip Speed High Conveyor Belt Chip size too big Regular

49

Cutter Malfunction Chip Cutter Malfunction

Chip cutter breakdown

Maintenance Process Checks

10.2 Nylon to Chip Cutter

Speed Low Conveyor Belt Malfunction Chip Cutter Malfunction

Chip size too small Regular Maintenance Process Checks

11.1 Chip Cutter Electrical Shut-down Power Outage Generator Malfunction Surges (Electrical Spikes)



11.2 Chip Cutter Speed High Chip Cutter Malfunction

Chip size too small Regular Maintenance Process Checks

12.1 Chips to Extruder 2




13.1 Extruder 2 (EXTRUDE2)




13.2 Extruder 2 (EXTRUDE2)




14.1 Filter Flow High Control Valve Failure

Fouling of filter Control Valve Close Maintenance check on extruder

15.1 Spinneret System

(SPINERET)

Flow High Spinneret Malfunction High pressure in tank



15.2 Spinneret System

(SPINERET)




50

Other Important Considerations Synthesis of HMDA to Combat High Raw Material Prices

Due to the high raw material price of HMDA compared to the proposed selling price of

Nylon 6,6 HMDA could be synthesized from inexpensive petroleum by-products. This route is

an important consideration to mention if the actual bulk price of HMDA underestimates the raw

material costs, since the bulk price is an assumption. There are many synthesis routes that can be

employed to produce HMDA at a smaller cost than buying from a large-scale supplier. The three

main methods of production are:29

1. Hydrocyanation of butadiene

2. Electrohydrodimerization of acrylonitrile

3. Ammoniation of adipic acid

All the proposed methods produce adiponitrile as a side product, which can also be

further processed to from HMDA. Butadiene is first reacted with hydrogen cyanide in the

presence of a nickel catalyst to form adiponitrile, and then is hydrogenated to form HMDA.

The second method of production is another two-step process which forms adiponitrile

from acrylonitrile through a redox reaction, and then is hydrogenated to form HMDA (same 2nd

step as hydrocyanation reaction).

The third method of production involves the use of adipic acid, which is a reactant that

has already been purchased. Adipic acid can undergo ammoniation to form adiponitrile, which is

then hydrogenated to form HMDA.

Since the two-step mechanism of each of these production routes forms adiponitrile as an

intermediate, a combination of the three methods outlined can be utilized to produce HMDA.

Any of the three methods can be performed independently for the first step, and then all the

produced adiponitrile can be hydrogenated to form the desired HMDA.

51

Figure 33. Schematic for potential production of HMDA to be used in Nylon 6,6 production.

Patent Availability and Product Lifecycle

The ability to patent the process is important to protect the integrity of the process

proposed and so competitors will not steal the ideas presented in this report. Table 28

summarizes how the patent field is currently for Nylon 6,6 production. Table 28. The number of patents for different field searches to determine the ease of getting patents for this process.30

Search Term #1 Search Term #2 Number of PatentsNylon - 240,568

Nylon 6,6 or Nylon 66 - 18,613 Nylon 6,6 Fiber 9,222 Nylon 6,6 Batch 2,875

Nylon 6,6 Fiber Continuous 99

Nylon 6,6 Fiber Batch 27

Thus, of course as one gets from general to more specific, the number of patents will

decrease in the United States Patent and Trademark Office. Of the 27 patents looked at in the last

search, there is only one patent that would need to be looked at for patent infringement, Patent

4,238,439. This patent was filed in 1977 and accepted in 1980 though and thus, its amortization

life is more than likely expired. Therefore, patents should be accepted for this process to protect

the economic life of the process.

In terms of where this process is at in the product life cycle, it has been determined that

the product is in the maturity phase.

52

Figure 34. General overview of product life cycle to show maturity phase.31 The largest barrier to growth of an individual company has been determined to be the

already existing market. While the market is expanding, this product has been around for

decades, so to enter into this market a unique product with special applications and low costs will

be needed. This process has been determined to be low cost in the long run and with the number

of patents for this exact process not exceedingly high, the production of Nylon 6,6 can be entered

into the market at the mature phase.

Exploring Additive Options for Nylon 6,6

Additives are utilized to enhance the properties of the fiber so that it can offer unique

advantages to the market. The additives would be added in the second extrusion process, melting

and homogenization, so that the additive will not affect polymerization and will mix evenly with

the Nylon 6,6. A few additive options will be discussed, but the affects on the economics cannot

be ignored. If additives are to be used, this will increase the cost of raw materials, but may also

increase the selling price, depending on which niche of the market is being targeted. It may also

be necessary to use the additive just to stay in the market and be competitive with other

producers, so the cost would have to be absorbed somewhere else in the budget if this were the

case.

The first additive to be discussed is Invista's Novadyn DT/DI.32 Since there is a relatively

high humidity in Calvert City, about 58%, Novadyn will increase the strength and stiffness of the

polymer in humid environments, which could a problem if it rains around the process time.33

Novadyn helps the polymer absorb less water and also creates a glossy appearance on the fiber

that increases the aesthetics of the product. The main advantage of Novadyn is the ability to enter

53

markets for water-resistant fibers such as in water/winter sports, refrigerators, and other

applications where the fiber may be exposed to water. Table 29 shows the effects of Novadyn on

the polymer. As much as a quarter of the final polymer solution can be made up of the additive,

which would need to be considered for batch sizes and raw material costs.Table 29. The difference in the main properties of polymers for Nylon 6,6 with and without the Novadyn additive is shown.32

A second additive options to consider is the Fusabond series produced by Dupont.34

Options include Fusabond N493 to increase the toughness only to the Fusabond A560 which is

for glossy appearances and moderate toughening. The Fusabond A560 still increases the

toughness of the polymer up to 50%, and the series as a whole has two unique advantages:

reduced overall viscosity of the melt and better retention of original properties (example: tensile

strength) that are not toughness for appearance purposes. Another advantage of this additive is

that it does not impede the ability to enter the food markets as the additive is not harmful when it

comes in contact with food sources.

The last additive option to be discussed is Nyrim from Brueggemann Chemical.35 Table

30 shows the changes in polymer attributes when Nyrim is added to the system.Table 30. The difference in the main properties of polymers for Nylon 6,6 with and without the Nyrim additive is shown.35

54

Nyrim provides a polymer that is able to withstand very low temperatures down to -40°C.

The additive allows the final polymer fiber to be molded to very exacting measures. Some

examples include mudguards, dentist chairs, and bulldozer trackpads. The low temperature

resistance allows the markets for winter products to be entered by the Nylon 6,6 product and

again provides other unique advantages against the other two additives discussed.

There are other additive options that will allow entry into other markets, but these three

additives are very highly rated. To use these additive, the economic costs and benefits must be

evaluated specifically before choosing. As is shown with the three options presented, different

markets are available that will allow demand for the products produced to be increased. With

five production lines in each option, this may allow a differentiation of products, even produced

at the same time to create a demand to be able to sell the products at a market price of at least

$1.86 per pound.

Increase in Demand Over Time/Decrease of Price – Further Commercialization

Two other considerations to look at are if the demand for the production of Nylon 6,6

increases at the plant and if the price of Nylon 6,6 continues a downward trend, how to absorb

the difference in revenue. First the demand of the product will be looked at and how the

expansion in the number of lines can offset an increase in demand of the plant. It is estimated

that the Nylon 6,6 market is growing globally at 8% per year. Table 31 shows how the number of

lines will increase with demand as well as total equipment costs and revenue to combat demand

assuming a stable price of $1.86 per pound. Table 31. Depicts the costs, revenue, and number of production lines associated with a demand increase of 8% per year. Year DemandofNylon

(lb.peryear)ExpectedRevenue

($)#ofProduction

LinesFCICost

($)1 85,000,000 158,100,000 5 44,445,5242 91,800,000 170,748,000 5 48,001,1663 99,144,000 184,407,840 5 51,841,2594 107,075,520 199,160,467 6 55,988,5605 115,641,562 215,093,305 6 60,467,6456 124,892,887 232,300,769 7 65,305,0577 134,884,317 250,884,830 7 70,529,4618 145,675,063 270,955,617 8 76,171,8189 157,329,068 292,632,066 9 82,265,563

55

10 169,915,393 316,042,632 9 88,846,80811 183,508,625 341,326,042 10 95,954,55312 198,189,315 368,632,125 11 103,630,91713 214,044,460 398,122,695 12 111,921,39114 231,168,017 429,972,511 13 120,875,10215 249,661,458 464,370,312 14 147,545,11016 269,634,375 501,519,937 15 157,988,71917 291,205,125 541,641,532 16 169,267,81618 314,501,535 584,972,854 17 181,449,24219 339,661,657 631,770,683 18 194,605,18120 366,834,590 682,312,337 20 208,813,596

This ability to be able to increase in demand is why a land size of 140 acres was desired

so that the plant could be expanded to fit any increase in demand. While this is a simple case that

assumes a constant demand change, it conceptualizes what is needed for such a large expansion.

Another factor to consider is an expansion on the plant, which would be required after the 13th

production line was input, assuming each line needs 2000m2 of space (20m x 100m). The

building costs would still remain the same rate as used before and would be about $860,000 per

added production line for the expansion. Assumed was the same sized plant to added to the

existing plant. The ease of expanding should not be difficult due to the large area of land to be

purchased and the replication of process lines from the other existing lines.

While the commercialization aspect shows an optimistic viewpoint of the plant, there is a

concern over the decrease in price of Nylon 6,6 over the past couple of years. Similar products

such as Nylon 6, textile yarn, and nylon chips have seen decreases as high as 18% in selling price

over a one year span. Shown in the sensitivity analysis for a decrease in price of just $0.05/lb.,

even small decreases in selling price will affect the bottom line of the company drastically.

While the price of Nylon 6,6 is expected to increase by three cents in 2017 in Europe and in

other areas around the world, the price of similar products were steadily rising and then hit a wall

as prices decreased due to an increase in production in China.

Conclusions and Recommendations

In conclusion, the batch reactor process line is the recommended process for the

production of 85,000,000 pounds of Nylon 6,6 per year. The economics of the process show it to

be the more stable process financially as it can absorb a decrease in demand better than the two

egrulke

Sticky Note

excellent solution!

56

alternative cases, and the process creates better results. While the economics of the process seem

to be volatile, additives to the product can help combat a rise in the price of raw materials and

entry in other markets to help the selling price of the fibers. Having five different process lines

allows for the ease of the differentiation of products as does the use of five different product

storage areas to keep unique products separate.

The plant layout, batch reactor schematics, and HAZOP table show the batch reactor

process to be thoroughly examined and to be a viable process. An increase in demand can be

easily mitigated in the plant as is depicted in Table 31. Expansion of the plant would not be

needed until the 14th process line is needed to meet demand. Overall, a thorough examination of

the process, economic, safety, and other considerations show the batch polymerization to be the

preferred process compared to continuous and a mixture of the two processes. The expectation is

to breakeven by year 5 if the demand stays constant at 85,000,000 pounds per year, and to make

an average net profit of $10.6 million per year. Increasing production would only make the

economics better and is also recommended if the market shares can be obtained.

Acknowledgements We would like to first thank Dr. Eric Grulke and Dr. Daniel Pack for preparing us for this

project through a semester of Design I. The five design problems issued in CME 455 were great

practice for the AIChE problem and their guidance throughout the first semester helped us to ask

ourselves the right questions. Next we would like to thank Dr. Christina Paynefor providing us

the knowledge and the templates for the safety considerations in CME 470. Lastly, we would

like to thank Dr. Tate Tsang for providing rigorous problems in MATLAB throughout our last

three semesters that helped us to model this dynamic process in MATLAB, with many different

changing conditions.

57

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Documents

AIChE National Student Design Problemcourses.engr.uky.edu/CME/cme456-001/cme 456 2018... · Dear AIChE Contest Judges, ... 10 12 - 15 Tensile Strength (psi) ~ 12,000 ~ 10,150 Since