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Chemical Plant Design – 1210384 Chapter-1

Department of Chemical Engineering - UPN “Veteran” Yogyakarta of 26

Dr.Eng. Yulius Deddy HermawanDepartment of Chemical EngineeringUPN “Veteran” Yogyakarta

IBasic Concept of Process Design

Dr. Eng. Y. D. Hermawan – ChemEng - UPNVY

Outline

1. Formulation of The Design Problem2. Chemical Process Design and Integration3. The Hierarchy of Chemical Process Design4. Onion Model5. Batch and Continuous Processes6. Capacity Estimation7. Pretreatment of Raw Materials




IFORMULATION OF THE

DESIGN PROBLEM


How does Chemical Process Plant come into being?

1. An idea:a. Completely new productb. Improvement of an existing product

2. Feasibility Study: reasonable profit?3. Research and Development: collect data (information) such as the

operating condition (P, T, F)4. Process Design: in this step, a Chemical Engineer:

a. decides what kind of equipments will be needed for eachoperation

b. calculates size of each itemc. organizes all information in the flowsheet (PFD and/or P&ID)

5. Project Engineering: pilot plant and full scale6. Construction Engineering7. Market Research Engineering




Formulation of The Design Problem

DesignProblem

ProcessDesign

Need productspecification:Purify spec.

for a specialty product (thefunctional properties ratherthan chemical properties):require a product design stage

Flowsheet

Operating andreacting condition

Capacity, energy

Recycle, heatintegration


Chemical Product(Smith, R, 2005)

• essential to modern living standards

• almost all aspects of everyday life are supported bychemical products in one way or another.

• 3 broad classes of chemical product:1. Commodity or bulk chemicals:2. Fine chemicals:3. Specialty or effect or functional chemicals




Commodity or Bulk Chemicals(Smith, R, 2005)

These are produced in large volumes and purchased onthe basis of chemical composition, purity and price.Examples are: sulfuric acid, nitrogen, oxygen, ethylene and chlorine.


Fine Chemicals(Smith, R, 2005)

These are produced in small volumes and purchased on thebasis of chemical composition, purity and price.Examples:

• chloropropylene oxide: used for the manufacture of epoxyresins, ion-exchange resins and other products

• dimethyl formamide: used, for example, as a solvent,reaction medium and intermediate in the manufacture ofpharmaceuticals

• n-butyric acid: used in beverages, flavorings, fragrancesand other products)

• barium titanate powder: used for the manufacture ofelectronic capacitors




Specialty or effect or functional chemicals(Smith, R, 2005)

These are purchased because of their effect (or function),rather than their chemical composition.Examples:

• Pharmaceuticals• Pesticides• Dyestuffs• perfumes• flavorings.


IICHEMICAL PROCESS DESIGN

AND INTEGRATION




Chemical Process Design and Integration(Smith, R, 2005)

• Transformation of raw material into desired productsusually can not be achieve in a single step, but trough somesteps as follows:

1. Reaction2. Separation3. Mixing4. Heating5. Cooling6. Pressure change7. Particle size reduction and enlargement8. etc.


Chemical Process Design and Integration(Smith, R., 2005)

• Synthesis of chemical process involves two broad activities:1. Selection of individual transformation step2. Interconnect individual transformation step to form

complete structures that achieves the required overalltransformation.

• Flowsheet: diagrammatic representation of the processsteps with their interconnection.

Once the flowsheet structure has been defined, a simulation of theprocess can be carried out. A simulation is a mathematical model ofthe process that attempts to predict how the process would behaveif it were constructed.





IIIHIERARCHY OF CHEMICAL

PROCESS DESIGN ANDINTEGRATION




Hierarchy of Chemical Process Design and Integration(Smith, R, 2005)

• Process Starts with the reactor.• The process requires a reactor to transform the FEED into

PRODUCT

Unfortunately, not all the FEED reacts.Also, part of the FEED reacts to formBYPRODUCT instead of the desired

PRODUCT.


Hierarchy of Chemical Process Design and Integration

A separation system is needed to isolate the PRODUCT at therequired purity.

• Reactor design dictates theseparation and recycle problem

• this flowsheet is probably tooinefficient in its use of energy

• Need heat integration




For a given reactor and separator design there are differentpossibilities for heat integration.


For a given reactor and separator design there are differentpossibilities for heat integration.




Changing the reactor dictates a different separation andrecycle problem


A different reactor design not only leads to a different separationsystem but additional possibilities for heat integration.




A different reactor design not only leads to a different separationsystem but additional possibilities for heat integration.


IVONION MODEL




Simplify Onion Model(Smith, R, 2005)

Reflect !!1. What does it mean? Process’ circle < operation circle < utility circle2. in case, if Industries do not involve the process/reaction? How about the

onion model?3. Does it possible if industries with un-concentred the onion model? Give its

examples

I

II

III

Raw materials Products

I. Process/ReactionII. OperationIII. Utility






VBATCH & CONTINUOUS

PROCESSES




Batch and Continuous Processes(Smith, R, 2005)

• However, not all processes operate continuously.• In a batch process, the main steps operate discontinuously.• In contrast with a continuous process, a batch process does

not deliver its product continuously but in discrete amounts.This means that heat, mass, temperature, concentration andother properties vary with time.

• In practice, most batch processes are made up of a series ofbatch and semicontinuous steps.

• A semicontinuous step runs continuously with periodic start-ups and shutdowns.


A Simple Batch Process(Smith, R, 2005)

Requiresheating

Requirescooling

Unfortunately, even if the reactor effluentis at a high enough temperature to heatthe feeding, the reactor feeding andemptying take place at different times,




Batch Processes:(R. Smith)

• are economical for small volumes;• are flexible in accommodating changes in product formulation;• are flexible in changing production rate by changing the

number of batches made in any period of time;• allow the use of standardized multipurpose equipment for the

production of a variety of products from the same plant;• are best if equipment needs regular cleaning because of fouling

or needs regular sterilization;• are amenable to direct scale-up from the laboratory and• allow product identification.


Batch Processes:(R. Smith)

One of the major problems with batch processing is batch to-batch conformity.

• Minor changes to the operation can mean slight changesin the product from batch to batch.

• Fine and specialty chemicals are usually manufactured inbatch processes. Yet, these products often have very tighttolerances for impurities in the final product and demandbatch-to-batch variation being minimized.




Batch Processes:(James M. Dauglas)

Select batch, if:1. Production rate

a. Sometimes batch if less than 10million lb/yearb. Usually batch if 1million lb/yearc. Multiproduct plant

2. Market forces:a. Seasonal productionb. Short product lifetime

3. Scale up problems:a. Very long reaction timesb. Handling slurries at low flowratesc. Rapidly fouling materials


VIPLANT CAPACITY

ESTIMATION




Production Capacity(Smith, R, 2005)

Production capacity is an important factor that needs to becalculated to:

• determine equipment size• satisfy contractual requirements• aid supply chain management• benchmark against competitors• obtain operating permits from regulator.

Production capacity is a central concept in:• production planning and scheduling• operations management

Production capacity depends on:• market• raw material availability


Production System Performance(Smith, R, 2005)

• The production capacity of a chemical plant is a fundamentalmeasure of its economic potential.

• A simple definition of capacity is the maximum through-putfor a single processing step

• For chemical manufacturing operations, the productionsystem usually takes the form of a series of processing steps(called a serial production system)




The important things to Determine Production Rates(James M. Dauglas)

1. If we want to design a new plant to meet an expandingmarket condition, first guess of the production rate based onthe largest plant that has ever been built.• The greatest economy of scale• Normally things are cheaper per unit if we buy them in

large quantitiies2. The maximum size of a plant is usually fixed by the maximum

size of one or more pieces of equipment to the plant site.3. The production rate specified for the plant might change

during a design because of the market conditions areconstantly changing we must be responsive to thesechanges

4. Product purity normally is also fixed by marketingconsideration.


Source: Russell A. Ogle, P.E., and Andrew R. Carpenter, P.E. 2014, AICHE Journal, p. 59 – 63.

Capacitydeppends on

the Bottleneck




VIIPRETREATMENT OFRAW MATERIALS


Raw Material Handling(James M. Dauglas)

1. Phase:a. solidb. liquidc. gasd. slurrye. solutionf. etc.

2. Impuritya. inertb. will affect to the reactions?c. Its separation and recycle

3. Its Properties:a. Density/viscosityb. volatilityc. corrosived. etc.

4. Operating/Storing condition: P, T, V.




Solid Feeder


Vertical Silo




Belt Conveyor


Bucket Elevator




Liquid Tank


Mixing Process




Preparing of Vapor/Gas Feed

Control strategieswould be discussed

next


Preparing of High Pressure Gas Feed

dry gas (FG)

coolant (FC)condensate (FL)

SEPARATOR

CONDENSOR

COMPRESSOR

flare (Fflare)

high pressure gas

gas feed (FF)

comp. suction

(Fsuct)

to oil pit

T, P

SPLITTER

Control strategieswould be discussed

next

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