Design of Liquid-Liquid Extractor 54

DESIGN OF LIQUID-LIQUID EXTRACTOR
Name of student
Institution
Date

EXECUTIVE SUMMARY
There are a number of activities that are carried out within the industrial sector. One
such instance includes the production of crude oil. However, these industrial activities in the
past have posed a great threat to biodiversity. They have threatened the existence of most
water living organism as well the well-being of the people. In this case, a case study is
looked, in which a feasibility study is to be conducted, and design of a plant which produces
120K ton/year of 70% hydrogen peroxide generated.
This plant besides, needs to be most efficient, best for the environment, profitable and
also safe for the people that live nearby this plant and the employees that are on direct contact
with the plant in order to make the product. In order to achieve this task, a range of process
routes will be analyzed in order to determine which route is the best to produce the 120,000
ton of the final product which should be 70% hydrogen peroxide per year. There are a few
commercial routes for this product as well as some that have recently been discovered, these
will all be investigated to determine which process route would be the most efficient and
profitable. Alongside this an evaluation of the market and product are to be carried in order to
evaluate the current market for the product, to assess whether the plant is worthwhile to build
for this process for the current situation in the chosen country of China.

Table of Contents
EXECUTIVE SUMMARY....................................................................................................................................2
NOMENCLATURE...............................................................................................................................................5
CHAPTER ONE (1): INTRODUCTION...............................................................................................................6
Purpose of the research.......................................................................................................................................6
Project Brief.......................................................................................................................................................6
Extraction...........................................................................................................................................................6
Liquid-Liquid Extractor..................................................................................................................................7
Assumptions:..................................................................................................................................................7
Chapter summary...............................................................................................................................................8
CHAPTER TWO (2): LITERATURE REVIEW...................................................................................................9
Extractive distillation..........................................................................................................................................9
Liquid-liquid extraction......................................................................................................................................9
Extraction process..............................................................................................................................................9
Flooding in sieve extractor:..............................................................................................................................10
Liquid-Liquid Extraction Column....................................................................................................................12
Columns:......................................................................................................................................................12
Sieve Trays.......................................................................................................................................................13
The design of a sieve tray extraction column................................................................................................13
Determination of sieve tower Diameter (DT):...............................................................................................14
Determination of the velocity through perforation (Vo):...............................................................................14
Determination of the tower Height (HT):......................................................................................................14
Determination of the theoretical trays (NT):..................................................................................................14
Heat balance over the plate...............................................................................................................................15
Determination of column efficiency (Eo):.....................................................................................................15
Determination of the number of actual stages...............................................................................................16
Chapter summary.............................................................................................................................................16
CHAPTER THREE (3): CHEMICAL AND MECHANICAL ENGINEERING DESIGN..................................17
Materials and methods......................................................................................................................................17
Choosing a solvent system:..............................................................................................................................19
Solvent Selection:.............................................................................................................................................19
Design parameters............................................................................................................................................20
Temperature..................................................................................................................................................20
Pressure........................................................................................................................................................20
Activity coefficients.....................................................................................................................................20
Viscosity.......................................................................................................................................................20
Equipment....................................................................................................................................................21
Mass balance and energy balance.....................................................................................................................21
Liquid Isobaric Specific Heat Capacity............................................................................................................21
Mean Heat Capacity Values.............................................................................................................................22

Enthalpy of Formation......................................................................................................................................22
Process Units....................................................................................................................................................22
Assumptions and Operational Conditions:.......................................................................................................22
Chapter summary.............................................................................................................................................25
CHAPTER FOUR (4): CONTROL AND INSTRUMENTATION......................................................................26
Introduction......................................................................................................................................................26
Countercurrent – multistage extraction process flow........................................................................................26
Mixture settler..................................................................................................................................................27
Columns...........................................................................................................................................................28
Centrifugal contactors......................................................................................................................................29
P& ID...............................................................................................................................................................30
Liquid-liquid extractors control........................................................................................................................31
Chapter summary.............................................................................................................................................31
CHAPTER SIX (6): HAZARD AND OPERABILITY STUDY..........................................................................33
Introduction......................................................................................................................................................33
Hydrogen Peroxide...........................................................................................................................................33
Hydrogen..........................................................................................................................................................33
Handling and storage........................................................................................................................................33
Hazop methodology..........................................................................................................................................36
Basic control measures to reduce risks.............................................................................................................38
Emergency action.............................................................................................................................................38
Chapter summary.............................................................................................................................................39
CHAPTER SEVEN (7): CONCLUSION AND REFLECTIVE STATEMENT...................................................40
Reflection.........................................................................................................................................................40
REFERENCES.....................................................................................................................................................41
APPENDIX..........................................................................................................................................................43

NOMENCLATURE
Entrainment -This term refers to the process by which movements are triggered by one
another.
Extraction process- The extraction process is the process by which liquids are separated
through contact by another liquid, which is not miscible with the solvent.
Extractive distillation - the distillation process in the presence of a high boiling, a non-
volatile component solvent which does not form an azeotrope with other components in the
mixture
HAZOP- The hazop technique is a systematic and structured assessment of the product,
procedure or process within the system. It is more of a qualitative technique and it is based on
the various operating conditions for the design process
Liquid-liquid extraction - is a technique, which is utilized for the separation of a solution of
liquid, through contact with an insoluble liquid or with another insoluble liquid. Also, it
represents the mass transfer operation whereby a liquid solution also known as a feed is
contacted with a nearly miscible solvent /immiscible solvent, which has characteristics of
selectivity towards more or one of the feed components.
Mixture settler- The mixer stellers enable a single-stage extraction
P & ID- A piping and instrumentation diagram is a schematic illustration that gives a display
of the various units which are to be utilized for a system/process including the control valves,
sensors as well as other units.
Phase inversion -This is the situation whereby the phase of liquid-liquid dispersion
interchange in way that dispersion phase is naturally inverted making process to continuously
occur and the other way round
Raffinate -. The solution, which gets from the bottom of the stream and has just a little
amount of the solute.
Solute- the Product That needs to be extracted and is contained at the top of a solution feed.
Solvent- the substance which has the extract and gets out through the column at the top,

CHAPTER ONE (1): INTRODUCTION
The industrial sector is composed of a number of activities which basically relies on
the different process, for instance, taking separation to be one of the processes, there are a
variety of products which needs to be separated in order to come up with the final desired end
results. The components, which have to be separated can either be liquids, solids or even
fluids. There exist various types of separation, which are present in the industry for the
separation of two or more components. Some of these separation methodologies include;
extraction, absorption, drying, distillation among others. When we narrow downs to the
separation of liquids, the methods that are likely to be applied includes distillation, extraction
and absorption1.
There are liquids, which are miscible, while others do not mix at all, thereby the
techniques which are used for the two cases are a bit different. Liquid-liquid extraction
methods is a technique, which is utilized for the separation of a solution of liquid, through
contact with an insoluble liquid or with another insoluble liquid. This process when compared
to the process of distillation it is found to be associate with numerous advantages, more so in
types of azeotropic compound and heat sensitivity.
There exist numerous devices for the liquid-liquid extraction which applies the
principle of gravitation and centrifugal force to achieve the main objective of separation,
however, these devices require some kind of mechanical activation so as to generate finer
dispersions as well as enhancing the mass transfer of the extracts. Some of these include the
vibrating plate column and the reciprocating column which are added mechanically.
Nonetheless, there has been more research which has been focused on the development of the
mechanically aided extraction columns, with major percentage focusing on the reciprocating
column. There are a number of parameters, which are required to be adjusted in order to
achieve the desired results such as height, diameter, tray spacing, frequency of the vibrations,
the final throughput, the amplitude as well as the individual flow rates.
Purpose of the research
The major purpose of this research is to produce a chemical and mechanical engineering
design which is based on the liquid-liquid extraction technique for the use of separation of
liquids. Essentially, there are three major stages, which are associated with the engineering
design of the process.
- Letting the feed mixture as well as the solvent into contact
- Separation of the phases
- Elimination of solvent and subsequent recovery from each of the phase
Project Brief
The objective of this project is to carry out a feasibility study to design a plant that
produces 120K ton/year of 70% hydrogen peroxide. The purpose is to design a plant that is
the most efficient, best for the environment, profitable and also safe for the people that live
nearby this plant and the employees that are on direct contact with the plant in order to make
the product. The chosen process route must have these qualities, and the advantages must
outweigh the disadvantages. To do this a range of process routes will be analysed in order to
determine which route is the best to produce the 120,000 ton of the final product which
should be 70% hydrogen peroxide per year.
There are a few commercial routes for this product as well as some that have recently
been discovered, these will all be investigated to determine which process route would be the
most efficient and profitable. Alongside this an evaluation of the market and product are to be
carried in order to evaluate the current market for the product, to assess whether the plant is
worthwhile to build for this process for the current situation in the chosen country of China
1 Hosseinzadeh, M.; Ghaemi, A.; Shirvani, M. Hydrodynamic Performance Evaluation Of A Novel Eductor
Liquid-Liquid Extractor Using CFD Modeling. Chemical Engineering Research and Design 2017, 126, 19-31

Extraction
The feed consists of only H2O2 and H2O which is the light phase stream from the
liquid-liquid extractor,70% H2O2 in the bottom product stream. The H2O2 that was formed in
the oxidation is now removed from all impurities. Water is added at this stage and a liquid-
liquid extractor is used. H2O2 is miscible in water whereas the rest of the impurities are not;
so through counter current extraction, the H2O2 is extracted from the impurities, and the
working solution can be re-formed and sent for treatment before being sent back to the
hydrogenation reactor.
Liquid-Liquid Extractor
There is no reaction occurring in this process unit. Water is fed into the extraction tower in
which it passes concurrently with the products from the oxidation step in order to strip the
H2O2 from the EAQ:
(H ¿¿ 2 O2+ EAQ )+(H ¿¿ 2 O) → ( H2 O2 + H2 O ) +(EAQ) ¿ ¿
Assumptions:
Extraction efficiency = 60% (refer to appendix 2, figure 12)
Consequently, there will be some H2O2 in the heavy phase leaving for post-treatment
From literature, it was found that the feed for the distillation column which is the outlet of the
extraction tower consists of 35wt% H2O2 and 65wt% H2O. (refer to section 3.5 figure 6)
50 kmol/h of water fed in (assumption made to calculate the initial mass balance around the
extractor)
We know the feed into the extractor based on the assumed values that are yet to be scaled,
from these values, we can conduct the mass balance around the extractor. From literature, it
was found that this sieve plate extraction tower has a 60% extraction efficiency meaning that
60% of the H2O2 produced will be extracted from the EAQ and form a mixture with the H2O,
so the remaining 40% will leave to go to post-treatment. As stated in the assumptions this
H2O2 is 35wt%, from these values and assumptions the mass balance was completed around
the extractor.
The molar flow rate of the outlet stream = 58.7 kmol/h
Component molar flow rate of H2O = 38.2 kmol/h
The component molar flow rate of H2O2 = 20.5 kmol/h (Nishimi et al., 2012)
(refer to appendix 3 to see the mass balance using assumed values)
From the mass balance around the distillation column, the values to produce 120K tonnes of
H2O2 are known. The scale factor can now be found in order to get the values needed to
produce the required amount2.
Scale factor = 15.18
Table 1 illustrates the mass balance around the oxidation reactor after multiplying by the
scale factor
Mass Balance around the extractor
IN OUT
Component
From
Oxidiser Water Stream
Light Phase
(Raffinate) Heavy Phase
kmol/
h
Wt
%
kmol/
h Wt% kmol/h Wt% kmol/h Wt%
EAQ
(C16H12O2)
1,354.
9 66.5 0.0 0.0 0.0 0.0 1,354.9 71.1
H2O2 519.9 25.5 0.0 0.0 311.9 35.0 208.0 10.9
2 Jin, Y.; Nagao, J. Morphological Change In Structure H Clathrates Of Methane And Liquid Hydrocarbon At
The Liquid-Liquid Interface. Crystal Growth & Design 2011, 11, 3149-3152.

H2O 0.0 0.0 759.1 100.0 579.3 65.0 179.8 9.4
H2EAQ 163.3 8.0 0.0 0.0 0.0 0.0 163.3 8.6
TOTAL
2,038.
1 100.0 759.1 100.0 891.3 100.0 1,905.9 100.0
Grand total 2,797.2 2,797.2
Assumptions and Operational Conditions:
Liquid-Liquid Extractor
Sieve Plate Extraction Column operating at a temperature of 50 and a pressure of 0.1 MPa.°C
(Cheng..). Maintaining a pressure of 0.1 MPa is more viable than maintaining one of 0.6
MPa, reduction in energy costs and a potential safety benefit to those working in the plant as
working at lower pressures reduces the risk of explosions due to over pressurization3.
Chapter summary
In this chapter, an introduction to the main aim of the research project is provided.
The project basically concentrates on the design of a liquid-liquid extractor column which
generates 120k ton per annum of 70% hydrogen peroxide. Further, the design project has to
ensure that it is sustainable, efficient and that it maximizes the overall profit in terms of the
output. The chapter begins by offering clear hindsight to the definition and overview of a
liquid-liquid extractor and the various associated principle such as the centrifugal and
gravitational force that influences the separation techniques. It defines the liquid-liquid
extraction as a technique, which is utilized for the separation of a solution of liquid, through
contact with an insoluble liquid or with another insoluble liquid.
After providing the project brief, the chapter also discusses the various theoretical
equations, which guides the whole process, inclusion of a number of assumptions and the
operational conditions that applies fir conducting the extraction process. The introduction
chapter is essential as it provides us with an overview of the project and what is to be done in
the sections that follow.
3 Hosseinzadeh, M.; Ghaemi, A.; Shirvani, M. Hydrodynamic Performance Evaluation Of A Novel Eductor Liquid-Liquid
Extractor Using CFD Modeling. Chemical Engineering Research and Design 2017, 126, 19-31