Design of PFR (Plug Flow Reactor) | Doc

SummaryThe project’s objective was to design a PFR (plug flow reactor) in hence be
able to produce ethanolamine(s) form reaction between ethylene oxide
and ammonia that is in liquid state with the absence of a catalyst. Heat
duty required by each reactor was determined according to properties of
thermodynamics and mass balance; it was found as −2.21 ×106 kJ /h
(i.e. the
three reactions were cumulatively exothermic). Each reactor’s
requirement was 12 pipes as found with an arrangement that is
rectangular, with a number of rows and columns required as 3 and 4. 0.25
m was the estimated inner diameter of each pipe while the outer diameter
estimated as 0.274 m as a result of high operating pressure. Each of the
rectangular arrangement of the reactor had an estimate of width and
height of 1.125 m and 1.5 m. poiseuille’s law helped obtain the pressure
drop of the reactors with an advantage in that there was a very small
pressure drop between the 4 reactors. Estimation and studying of each
reactor’s essential stresses were done with a realization that they were
safe. There was the design of two pumps (P-101 and P-102) and attached
heaters (E-101) was done with a requirement of power of the pumps as
0.98 kW and 78.11 kW with the area of a heater as 1.74 m2 .ultimately,
P&ID and the engineering drawings were designed based on the found
result.
I

Table of Contents
Summary......................................................................................................I
List of Tables..............................................................................................IV
List of Figure...............................................................................................V
1.0 Introduction........................................................................................1
2.0 Aim and Objectives.............................................................................1
3.0 Process Flow Diagram (PFD) of Ethanolamine(s) Reactor...................2
4.0 Mass balance of Ethanolamine(s) Reactor..........................................3
5.0 Energy balance of Ethanolamine(s) Reactor.......................................3
6.0 Mechanical Design of Ethanolamine(s) Reactor..................................5
6.1 Main Physical Dimension of Ethanolamine(s) Reactor........................5
6.2 Residence time of Ethanolamine(s) Reactor......................................9
6.3 Pressure Drop of Ethanolamine(s) Reactor........................................9
6.4 Material construction of Ethanolamine(s) Reactor...........................11
6.5 Thickness and outer diameter of Ethanolamine(s) Reactor.............11
6.6 The Stress study of Ethanolamine(s) Reactor..................................12
6.7 Sizing of Main Pipes of Ethanolamine(s) Reactor.............................14
7.0 Piping and Instrumenting Diagram (P&ID)..........................................15
8.0 Shut-down and Start-up of Ethanolamine(s) Reactor.......................17
9.0 Ancillary Equipment of Ethanolamine(s) Reactor.............................18
9.1 Heater (E-101)..................................................................................18
9.2 Pumps (P-101) and (P-102)..............................................................19
10.0 Conclusion........................................................................................20
Reference..................................................................................................21
Appendix (1): Mass Balance of Ethanolamine(s) Reactor..........................22
Appendix (2): Energy Balance of Ethanolamine(s) Reactor.......................27
II

Appendix (3): Mechanical Design of Ethanolamine(s) Reactor..................29
A3.1 Main Physical Dimension of Ethanolamine(s) Reactor...................29
A3.2 Residence time of Ethanolamine(s) Reactor..................................31
A3.3 Pressure Drop of Ethanolamine(s) Reactor....................................31
A3.4 Thickness and outer diameter of Ethanolamine(s) Reactor...........32
A3.5 The Stress study of Ethanolamine(s) Reactor................................33
A3.6 Sizing of Main Pipes of Ethanolamine(s) Reactor...........................34
Appendix (4): Piping and instrumenting of ethanolamine(s) reactor.........37
Appendix (5): Ancillary Equipment............................................................39
A5.1 Heater (E-101)...............................................................................39
A5.2 Pumps (P-101) and (P-102)............................................................39
Appendix (6): Engineering Drawings.........................................................41
III

List of Tables
Table 1: The actual mass balance of ethanolamine(s) reactor after scaling-
up................................................................................................................3
Table 2: Thermal properties of all materials in the plant............................4
Table 3: The volume calculations of 4 ethanolamine(s) reactor..................7
Table 4: Constant to determine the bundle diameter (Towler& Sinnott,
2012)...........................................................................................................8
Table 4: Positive displacement and centrifugal pump comparing table (Elie
et al., 1993)...............................................................................................19
Table 5: The summary of results of design pumps (P-101) and (P-102)....20
Table 6: The results of mass balance in molar basis (Zahedi, & Amraei,
2011).........................................................................................................22
Table 7: The summary result of molar flowrate of ethanolamine(s) reactor
zone (basis)...............................................................................................25
Table 8: The heat flow or enthalpy of each stream without heat formation
..................................................................................................................28
IV

List of Figure
Figure 1: Process flow diagram of Ethanolamine(s) reactor........................2
Figure 2: The reaction curve in which it shows relation between the rate
and the conversion of limiting reactant (EO)...............................................7
Figure 3: The elevation side of each reactor (pipes) based on calculation
value............................................................................................................9
Figure 4: Moody Chart (Gerhart et al., 2016)............................................10
Figure 5: The design strength of carbon steel based on operating
temperature (185 F)..................................................................................11
Figure 6: PID of the inlet section to the reactors.......................................37
Figure 7: PID of the ethanolamine(s) reactor............................................38
V

1.0 Introduction
The metallic vessel used to maintain reactions hence to generating a new
and required component or product is a chemical reactor. Chemical
reactor’s design and selection are based on diverse features of chemical
engineering such as kinetics of chemical reactions, chemical law or
equation of thermodynamics. Mass transfer factor which in some cases
the reaction rate is diffusion-controlled instead of kinetics of chemical
reactions, chemical factor that is the conversion and residence and then
heats transfer factor that is the control of heat of reaction by removal and
addition, then the safety factor which is the controlling possibility for
operation pressure and temperature so as the hazardous component and
finally factor of economics with the consideration of effectiveness of
reactor process are requirements to be satisfied in addition to the reactor
design and selection (Conesa, 2019).
2.0 Aim and Objectives
The project’s target is the production of ethanolamine(s) reactor’s study
and design from the reaction of ammonia and ethylene oxide in the
presence of water. Also, the project has various aims that can be
demonstrated as follows:
1) Ethanolamine(s) reactor’s process flow diagram description.
2) Chemical engineering aspects and literature reviews that bring
about the Mass balance of ethanolamine(s) reactor.
3) Balance of Energy of ethanolamine(s) reactor from laws and
properties of thermodynamics.
4) Mechanical design of ethanolamine(s) reactor in order to specify the
required volume, length, diameter of a reactor, number of pipes
inside the reactor, residence time of reaction, type of construction
material of reactor, and minimum thickness.
5) Instrumenting diagram and piping design that shows controlling
loops and pipe specifications.
1

6) The ethanolamine(s) reactor operation’s start-up and shut down
steps.
7) Pumps (P-101 and P-102) and Heater (E-101) design.
3.0 Ethanolamine(s) Reactor PFD (Process Flow
Diagram)
Consider the figure below (PFD) of Ethanolamine(s) reactor as Figure 1:
Figure 1: Process flow diagram of Ethanolamine(s) reactor
As above in Figure 1, feeding of the ethylene oxide to the plant is done via
stream 101 at 10 C and 1 bar and mixed with an aqueous ammonia
solution (91 mol% NH3) in the stream 103. Ethylene oxide’s feed is mixed
with aqueous ammonia and then pumped (P-102) in order to increase
pressure to 102 bar as well as heated to 85 ° C (i.e. required operating
conditions of reaction). The composition of streams 105 and 106 is 15 mol
% of ethylene oxides, 77 mol% of ammonia and the balance is water.
Demonstration of the reactions inside the reactor (R-100) can be(Zahedi,
& Amraei, 2011):
C2 H4 O+ N H3 → C2 H7 NO
Ethylene oxide+ Ammonia → Mono−methanolamine( MMA )
C2 H4 O+C2 H7 NO →C4 H11 N O2
Ethylene oxide + ( MMA ) → di−methanolamine ( DMA)
2

C2 H4 O+C4 H11 N O2 →C6 H15 N O3
Ethylene oxide+ ( DMA ) → tri−methanolamine (TMA)
Water’s presence in the reactor can act as a catalyst with the conversion
of ethylene oxide being 100% while ammonia’s conversion at 13% and the
selectivity of DEA and MEA is 33% and 42%. Notably, 4 series reactors are
there as well as intercoolers and three intermediate pumps in order to
adjust the loss of pressure and temperature between the reactors (Zahedi,
& Amraei, 2011).
4.0 Ethanolamine(s) Reactor’s mass balance
This part’s aim is to apply mass balance equations and aspects to produce
10,000 tons/year of ethanolamine based on the route of SRI process
production. Before commencing mass balance, the following assumptions
should be maintained and applied during calculations (Zahedi, & Amraei,
2011):
1. No accumulation as the process is steady-state.
2. The mass calculation basis of ethylene oxide is assumed as 100
kmol/h.
3. The conversion of ethylene oxide is 100% and ammonia is 13%.
4. Ammonia to ethylene inlet molar ratio is 5.
5. All three reactions have occurred inside the reactor.
6. 8200 hours are the working hours of the process.
7. The make-up amounts of ammonia and ethylene oxide are totally
pure.
Considering the calculations in Appendix 1 and above assumptions,
after scaling up, the actual mass balance of ethanolamine(s) reactor
presented as follows Table 1:
Table 1: The actual mass balance of ethanolamine(s) reactor after scaling-up
Compone
nt
101 102 103 104 105 106 107
kmol/
hr kmol/hr
kmol/
hr kmol/hr
kmol/
hr
kmol/
hr kmol/hr
C2H4O 22.00 0.00 22.00 22.00 22.00 22.00 0.00
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