ASPEN Plus Process Simulation: Hydrogen peroxide Quality (Lab Report Sample)

PRODUCTION OF PHENOL
(Student F. name, L.name, Email)
ASPEN Plus Process Simulation
For ASPEN simulations of the phenol production process, we will use a zeolite catalyst. The material dissociates into ion during the process and hence dissolves. The EPNRTL property method was employed in the implementation of the simulation throughout the report.
Assumptions
1 Catalyst Solubility
The zeolite catalyst used was not well defined. Hence, there was the need to make meaningful assumptions. This is because the solubility of the catalyst will influence the separation section of the process i.e. can result in clogging of the pipe and the distillation column trays. From the IUPAC analysis, most of the catalysts parts were soluble.
2 Acetone Minimization
Assumptions had to be made in regards with the solvent required for the process. From the analysis of water, acetone and the benzene mixtures in the reactor, it was necessary to maintain the miscible single-phase solution at 22 psi.
Ternary Map of Water/Acetone/Benzene at 22 psi & 140 F
3 Hydrogen peroxide Quality
Commercially obtained hydrogen peroxide have additives to enhance their stability. The quantity of the stabilizers will always increase with the increase in the strength of the hydrogen peroxide. The analysis assumes that the hydrogen peroxide does not contain stabilizers so as to avoid them being present in the system.
4 Waste Treatment
The project will assume that waste treatment already does exist or will be included due to the nature of the chemical processes carried out.
Simulation in ASPEN plus
Discussion
The reactor is where the primary process of propylene and benzene react hence has to be modeled as specified in the components list. The alkylation and trans-alkylation reactors are modeled separately. A temperature range of 300-400 oC and pressure of 25 atm are adopted.
Using the equilibrium condition pressure is not considered as the reaction occurs at equilibrium pressure but is dependent on temperature and the benzene/propylene ratio. ASPEN Plus has seven reactor models available. The equilibrium dependent RGIBBS reactor is executed in fathoming the constituents of the substance where free enthalpy of the product is at its lowset
The temperature approach for each reaction is implemented while the feed stream mole flow rate is maintained at a value of one kmol/hr and the feed stream comprises of propylene and benzene. The temperature of the reactor is set at 350 oC and pressure at 25 atm. The effects of variation of temperature and the selectivity in the conversions are monitored.
The calculations made are based on the following formula
%Selectivity of cumene = Fcumeneproduct /(Fpropylenefeed-Fpropyleneprod) x 100%
%Conversion of propylene = (FpropylenefeedFpropyleneprod)/Fpropylenefeed x 100 %
%Selectivity of m-DIPB = Fmdipbproduct/(Fpropylenefeed-Fpropyleneprod) x 100%
%Selectivity of p-DIPB = Fpdipbproduct/(Fpropylenefeed-Fpropyleneprod) x 100%
Where
Fcumeneproduct = molar flow rate of cumene in product
Fpropylenefeed = molar flow rate of propylene in feed
Fpropyleneprod = molar flow rate of propylene in product
Fmdipbproduct = molar flow rate of m-DIPB in product
Fpdipbproduct = molar flow rate of p-DIPB in substance.
RSTOIC reactor models was adapted in finding the standard heat of reaction for the various reactions
Impact of temperature and benzene/propylene concentration on the reaction.
The conversion of propylene increased with addition of the benzene/propylene concentration for a given temperature. This is due to the reduced proportion of propylene in the feed. The conversion of propylene was found to be decreasing with every addition of heat applied for a constant benzene/propylene concentration as a result of the reaction being exothermic. Finally, the selectivity of Cumene increased with each rise in benzene/propylene concentration at a given temperature as the polyalkylation reactions become reduced due to the excess amount of benzene. The increase in temperature increases the selectivity of Cumene for any static benzene/propylene concentration like trans-alkylation reactions being endothermic occur at high temperatures.
* Impact of increase/decrease in temperature and benzene:propylene concentration on conversion of propylene.
* Impact of increase/decrease in temperature and benzene:propylene concentration on selectivity of cumene
* Impact of increase/decrease in temperature and benzene:propylene concentration on selectivity of m-DIPB and p-
DIPB.
This process of phenol production involves purified or recycled cumene being oxidized. Cumene is fed in a stream into the oxidation vessel which is maintained at 110-115 oC and pH range of 6.0 to 8.0. This mixture is maintained exposed to compressed air until at least 20-25% of the cumene is converted to cumene hydroperoxide
This crude mixture is concentrated to 80% then injected to a reactor where the Cumene hydroperoxide is cleavage to phenol and acetone at around 70 oC and the atmospheric pressure. The reaction requires a small amount of Sulphuric acid so as to take place.
The stream is then directed to the separation process, but first, it is washed in water, and the acetone is removed as the overhead in the first column. The mixture is then purified by successive distillation. In the first column, the unreacted Cumene is transferred to the recycle stream. This cumene is treated before sending it back to the feed stream.
The purification process is through catalytic hydrogenation of Methyl Styrene to cumene; this achieved through careful fractionation where methyl styrene is obtained as a by-product.
The reaction of phenol was in two steps. The first reaction is the production of Cumene hydroperoxide by two raw materials i.e. cumene and oxygen. The reaction takes place in the oxidizing tower at 110-115 oC and pH range of 6.0 to 8.0. The intermediate product which is cumene hydroperoxide is used as a reactant in the second reactor, the reactor intended to be used is the Continuous Stirred Tank Reactor (CSTR). Most of the conversion occurs here i.e. about 90%. In the separation process, the side product and waste are removed to get the primary product i.e. Phenol.
Basic Process Flow Diagram and background
Figure 5: Block diagram for the process of Phenol
So as to do a simulation the phenol production process is composed of two processes i.e. oxidation and cleavage of Cumene
Hock process (oxidation of cumene)
10858502730500C6H5CH (CH3)2+O2 C6H5C (CH3)2OOH
C6H5CH (CH3)2+1.5O2 → (CH3)2C6H3CH2OH
Cleavage reaction
(CH3)2C6H3CH2OH → C6H4 (C2H3) CH3 + H2O
C6H5C (CH3)2OOH → C6H5OH + CH3COCH3
Aspen process flow diagram
Table of distillate at various stages
From the diagram the process has six steps
1 Oxidation of Cumene to obtain hydroperoxide
2 Cumene hydroperoxide concentration
3 Cleavage(decomposition of Cumene hydroperoxide)
4 Effluent neutralization
5 Purification
6 Effluent treatment
ASPEN plus report
Equipment to be purchased
1 Pump (p-201)
To increase the pressure of benzene feed to 3000 kPa
2 Pump (p-202)
To increase the pressure of propylene feed to 3000 kPa
3 Heater
Vaporizes and superheats the mixture of the feed to 350 oC
4 Reactor
Where the conversion of the limiting reactants take place.
5 Flash vessel
The combination of the heat exchanger and a flash drum. Aimed at lowering the temperature and pressure to separate inert propane and unreacted propylene from the Cumene and benzene.
Hand calculation of reactants in the reactor.
Material and Energy Balance
The reaction in the first reactor shows that the one kmole of C6H5CH (CH3)2 and one kmole of O2 will produce one kmole of C6H5C (CH3)2OOH. Also in the presence of Sulphuric acid (H2SO4), one kmole of C6H5C (CH3)2OOH will cleavage one kmole of C6H5OH and one kmole of CH3COCH3. Using the following standard relationship we can calculate the masses involved in the production of phenol.
Rate of mass input = Rate of mass output
Phenol production in a year =136363.64 tonnes / year
= 15.56663 tonnes / h
= 15566.63 kg / h
= 165.6 kmole / h
Fraction of composition of the product in the cumene hydro peroxide in the mixture in the first reactor
X3cumene = 0.6
X3cumene hydro peroxide = 0.3
X3oxygen = 0.1
Conversion factor:
X reactor 2 = 90%
To obtain the molar rate in reactor 1 we first calculate the
Molecule Balance on reactor 2 (acidifier).
Phenol Balance:
N3X3phenol = N4X4phenol – ar2 N4X4phenol
=> 165.6 kmole / h
a = 1
0 = N4X4phenol – r2 r2
= 165.6 Kmole / h
Acetone Balance:
N3X3acetone = N4X4acetone–ar2
N4X4acetone = 165.6 kmole / h
Cumene Peroxide Balance:
N3X3cumene hydro peroxide= -ar2 / Xreactor2
= - (-1) (165.6) / (0.9)
= 184 kmole / h
Total number of mole in feed reactor 2, N3
N3X3cumene hydro peroxide= 184 kmole / h
X3cumene hydro peroxide= 0.3 N3 (0.3) = 184 kmole / h
N3 = 613.3 kmole / h
Finding mass flow rate for feed in reactor 2.
F3 = N3X3cumene (Mr cumene) + N3X3 cumene hydro peroxide (Mrcumene hydro peroxide) + N3X3oxygen (Mr oxygen)
=> (613.33) (0.6) (120) + (613.33) (0.3) (150) + (613.33) (0.1) (32) = 73722.26 kg / h
The values obtained indicate that reactor 2 would require 73722.26 kg/h of the Cumene hydro peroxide and Cumene and oxygen to produce 15566.63kg/h of phenol at the conversion rate of 90%.
To fully perform the material and energy balance in the system (hysys) there is a need to draw the conversion chambers and their respective input and output streams.
Comparison of the ASPEN plus results and the hand calculation result...