Electrolyte Process Designfor HCl Separationswith PRO/II and OLI

OLI Simulation Conference 2016

25-26 October 2016

Dr.-Ing. P. Pöllmann, AQSim EUROPE

OLI Systems, Inc.

Cited from:http://www.olisystems.com/about-us

OLI Systems, Inc.

Cited from:http://www.olisystems.com/technology-scope

OLI MSE Engine in PRO/II

OLI and SimSci partnership: two levels

• OLI embedded in PRO/II as PRO/IIe• SimSci purchased the OLI model in 1983• OLI full support provided for the next 33 years

• All OLI solver improvements made for the PRO/IIe software as well as for OLI

• All OLI database improvements were made for only the PRO/IIecomponents

• PRO/IIe contains a subset of the components in OLI’s AQ (Aqueous) model

• OLI MSE Engine in PRO/II as a joint product with OLI - SimSci• An additional capability beyond PRO/IIe• Full OLI’s AQ model databank • Using the OLI MSE (Mixed Solvent Electrolyte) framework

• Makes accurate simulation of highly concentrated systems possible

Process Simulation … Flowsheet Given

Classical Approach Using a Process Simulator:1) Draw flowsheet2) Define components3) Select thermodynamic methods4) Supply data for feeds5) Supply operating conditions for unit operations6) Run7) Analyse results8) New operating condition? If yes, then 5)9) New feed case? If yes, then 4)10) Communicate results

Process Design … Flowsheet Unknown

Classical Approach:1) Define process design objective (PDO)2) Define components3) Select thermodynamic methods (and check validity)4) Supply data for feeds (representative to PDO)5) Draw or modify flowsheet6) Supply operating conditions for unit operations7) Run8) Analyse results9) PDO fulfilled? If no, then go to 5)10) Communicate new flowsheet (decide alternatives)11) Simulate feed cases and operating points

Process Design Objective

HCl + WaterWater

HClExtractiveDistillation

HydrochloricAcid

Process Design Objective

Water

HClExtractiveDesorber

BRINE Regenerator

HCl + Water

ExtractiveDistillation

BRINE

This presentation

HydrochloricAcid

Process Design Objective … Extractive Desorber

BRINE + Water

HClExtractiveDesorber

HCl + Water

BRINE

Extractive agentin BRINE:CaCl2 in aqueoussolution.

Thermodynamic Model Validity

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

HC

l in

vap

or,

wt.

-%

HCl in liquid, wt.-%

VLE of Hydrochloric Acid with Calcium Chloride1 atm / Parameter: CaCl2 wt.-% / lines: OLI MSE / dots: Lutz (1994)

0

10

20

30

40

50

0 exp

10 exp

20 exp

30 exp

40 exp

50 exp

Thermodynamic Model Validity

Validation Plot is property of OLI Systems, Inc.

Dots: Experimental data

Line:OLI MSE modelprediction

Thermodynamic Model Validity

Cited from:http://www.osi-univers.org/IMG/pdf/CalciumChloridHandbook-2.pdf

Back in 2003, The DOW Chemical Company distributed a handbook on calcium chlorideproducts. They show this diagram for thetemperature increase in dissolving a specialproduct or anhydrous CaCl2 in water.

For example, the heat generated in preparing a 40% calcium chloride solution with anhydrouswould result in a temperature increase ofapproximately 91 K (164 F).

The OLI MSE model predicts 91.8 K.

Feed Data

BRINE + Water

HClExtractiveDesorber

HCl + Water

BRINE

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

Feed:1 t/h HCl,as 18% acid, 25°C

Extractive Agent:10 t/h CaCl2,as 50% aqueous,boiling

Chemistry Setup OLI Chemistry Wizard

1) Launch OLI Chemistry Wizard 2) Select MSE Framework

3) Select Components 4) Finish to find dbs file

Chemistry Setup PRO/II

1) Thermo Button 2) Modify Button

3) Find ComponentSelection listextended

4) Specify in Terms of ApparentSpecies

Process Design Objective … Rules of the Game

BRINE + Water

HClExtractiveDesorber

HCl + Water

BRINE

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2Supply 1 MW heating duty

Product:HCl gas dry 0°C

By-Product:Dilute BRINE,reasonable HCl impurity

Feed:1 t/h HCl,as 18% acid, 25°C

Extractive Agent:10 t/h CaCl2,as 50% aqueous,boiling

Keep specifications fixed.Free to modify everything else.

Evaporator

Result

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

E1: FlashDuty = 1 MWPressure Drop = 0

V-E1

vapor

910.6Water

696.9HCl

0CaCl2

L-E1

liquid

13645Water

303.1HCl

10000CaCl2

1) HCl is squeezed out nicely2) … but also loads of water,

so that product drynessspecification is violated.

3) There is an intolerable lossof HCl via the liquid.

Dry the product gas by condensation ...

Insight

What next …

Unit E1 is supposed to- mix ACID with BRINE,- heat the mixture up, - evaporate it partially, - and separate V from L, by a

VLE calculation.

This will be in thefocus next.

SpecificationPressure is 1 atmby default

1000 HCl should bekg/h

Condenser 0°C

E2: FlashTemperature = 0°CPressure Drop = 0

V-E2 is missing. E2 hasachieved total condensation. Actually, V-E1 is gaseoushydrochloric acid with 43% HCl, which is fully condensedat 11°C.

Since HCl is known to bea gas, unit E2 is supposedto cool vapor V-E1 down to 0°C to condense out most of the water.

Go for less aggressive condensation ...

This is the new thing.

This will be in thefocus next.

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

E1: FlashDuty = 1 MWdP = 0

These data are same asbefore. From now on, only new informationshall be shown.

Condenser 50°C

V-E2 is present now. It isHCl gas, saturated withwater at 50°C.

By balance, the loss of HCl via liquids L-E1 and L-E2 isan intolerable 840.

Unit E2 is re-specified tocool V-E1 down to 50°C.

V-E2

vapor, 50°C

1.99Water

160.6HCl

0CaCl2

L-E1

liquid

13645Water

303.1HCl

10000CaCl2

L-E2

liquid, 50°C

908.7Water

536.2HCl

0CaCl2

E2: Flash Temperature = 50°CPressure Drop = 0

Find a place for L-E2 in the process ...

RefluxCondensate L-E2 isconnected back to theevaporator E1 as a process reflux.

V-E2

vapor, 50°C

5.447Water

439.7HCl

0CaCl2

L-E1

liquid

14550Water

560.3HCl

10000CaCl2

By the principle offractionation, partiallyrefluxing separatedmaterial, the loss of HCl is brought down to 560 now.

Go for final productspecification …

Condensation Train

V-E3

HCl gas, 0°C

0.0696Water

437.5HCl

0CaCl2

L-E1

liquid

14555Water

562.5HCl

10000CaCl2

E2: FlashT = 50°CdP = 0

E3: FlashT = 0°CdP = 0

M1: MixerdP = 0

V-E3 is HCl gas, saturatedwith water at 0°C, meeting productspecification on the gas side. But still, the loss ofHCl is prohibitive.

base

Vapor V-E2 at 50°C is dry enough to be cooledfurther down, to 0°C.

Condensates arecollected and fed back asa mix to the process.

Split the combinedjobs done at E1 …

ReboilerV-E3

HCl gas, 0°C

0.104Water

652.0HCl

0CaCl2

L-E1

liquid

14555Water

348.0HCl

10000CaCl2E1: FlashDuty = 1 MWdP = 0

T1: FlashDuty = 0dP = 0

The split of jobs was verybeneficial, because itcorresponds to theaddition of oneseparation effect to thefractionation.

The job to introduceheating duty to thesystem is taken out as an extra step.

+ 214.5

Split the combinedjobs done at T1 …

Feed Mixer

V-E3

HCl gas, 0°C

0.105Water

657.0HCl

0CaCl2

L-E1

liquid

14555Water

343.0HCl

10000CaCl2

T1: FlashDuty = 0dP = 0

S1: FlashDuty = 0dP = 0

The job to mix the feedmedia is taken out as an extra step, done in unitT1.

With the benefit in HCl production being onlysmall, it is highlyrecommended to mix thevery different media ACID and BRINE in front of thesystem. The more so, as a vapor is released by theheat of mixing.

V-T1

vapor

50.2Water

106.9HCl

0CaCl2

+ 5.1

Test the other placefor the reflux …

Reflux plus Feed MixerV-E3

HCl gas, 0°C

0.106Water

665.3HCl

0CaCl2

L-E1

liquid

14555Water

334.7HCl

10000CaCl2

Very strong hydrochloricacid condensate increasespre-evaporation in T1, which is welcome.

V-T1

vapor

62.7Water

169.7HCl

0CaCl2

+ 8.3

Condensate reflux isconnected down to thefeed mixer tank, fromwhere material istransferred to theseparation anyway.

+ 62.8

Try stronger BRINE …

Stronger Brine

BRINE

boiling

8181.8Water

0HCl

10000CaCl2

10 t/h CaCl2 as55% aqueous

V-E3

HCl gas, 0°C

0.137Water

860.2HCl

0CaCl2

L-E1

liquid

12737Water

139.8HCl

10000CaCl2

Water, the solvent, orcarrier of extractivespecies, is reduced.

… tremendous increaseof production. The system needs to processless water. By the logic ofthe example, fixedreboiler duty can beturned into moreseparation effect.

+ 194.9

Look into heat recovery …

Heat Recovery / 1 of 2V-E3

HCl gas, 0°C

0.144Water

904.3HCl

0CaCl2

L-E1

liquid

12737Water

95.7HCl

10000CaCl2

E4: Simple HXHot T = 100°CdP = 0

E5: Simple HXCold T = 90°CdP = 0

E5 E4

required available

Cold T Duty Hot T Duty

°C 1e6 kJ/h °C 1e6 kJ/h

90 1.216 100 0.826

95 1.689

Idea: Preheat feed ACID to 90°C, by use of latent heat of condensation.

As it appears, the targetof 90°C should befeasible.

Required and availableenergy flows need to bematched, and a feasibletemperature differencefor the heat transfermust be respected.

+ 44.1

Rearrange theflowsheet …

Heat Recovery / 2 of 2

E2: Simple HXCold T = 90°CdP = 0

HCL

gas, 0°C

0.145Water

912.3HCl

0CaCl2

L-E1

liquid

12737Water

87.7HCl

10000CaCl2

+ 8.0

Invest onemore stage …

New: - Feed

interchanger hotand cold sidescombined

- Condensersfollowed bytanks

- Utilities tocondensers

- Major flowsheetrearrangement.

Separation Stage #2 HCL

gas, 0°C

0.153Water

962.3HCl

0CaCl2

L-E1

liquid

12737Water

37.7HCl

10000CaCl2

S1, S2: FlashDuty = 0dP = 0

Flash stackmodel offractionateddistillation with2 stages.

Having checkedeverything elseis the right time to invest foranother stage.

+ 50.0

Go for a column …

Column

T5: Distillation5 stagesL-T1 to stage 1No condenserKettle reboilerDuty = 1 MWdP = 200 mbar

HCL

gas, 0°C

0.158Water

992.2HCl

0CaCl2

L-E1

liquid

12737Water

7.8HCl

10000CaCl2

Wasting 1% offeed HCl is takenas reasonable in the example.

The previoussequence of stepsprove the shownsystem to befeasible in theoryto separate 18% HCl acid, using a specific energydemand of 1 MW per t/h, exclusivethe regenerationof extractiveagent.

BRINE

boiling

8181.8Water

0HCl

10000CaCl2

10 t/h CaCl2 as55% aqueous

1 t/h HClas 18% acid

ACID

25°C

4555.6Water

1000HCl

0CaCl2

+ 29.9

Process Design Step Impacts Base: 437.5

0 50 100 150 200 250

Reboiler

Feed Mixer

Reflux plus Feed Mixer

Stronger BRINE

Heat Recovery (1 of 2)

Heat Recovery (2 of 2)

Separation Stage #2

Column

Production Increase, kg/h

Extractive Distillation PFD following EN ISO 10628

E1

E3

E4

C1

E2

P1 P2P3

Steam

T5

E5

Steam

CW

ACID

Water HCl

CCW

T1

BRINE

Conclusions

An intuitive method for the design of the flowsheet connectivity for hydrochloricacid separation by extractive distillation has been presented. The method is not limited by the kind of extractive agent.

The process system makes use of pre-evaporation, which occurs at the point ofmixing feed acid with extractive agent, and which can even be enhanced by pre-heating the feed acid by latent heat of condensation. This way, an energy savingflowsheet can be suggested.

Thermodynamic properties, with heat effects in particular, can very rigorously bepredicted for the physico-chemical system Water / HCl / Calcium Chloride by theMSE model of OLI Systems, Inc.

Thanks to smooth interfacing between the OLI Engine and PRO/II, process design for electrolyte flowsheets can be performed very efficiently.

Contact:

Feed Data … Takeout

BRINE + Water

HClExtractiveDesorber

HCl + Water

BRINE

Feed is 1 t/h HCl as 18% acid

Extractive agentis 10 t/h CaCl2as 50% aqueous,coming fromregenerator

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

Remark on extractive agent flow:VLE has suggested a good separation effect, if40% of extractive species prevail. Shall thishold for the BRINE + Water flow, then thechoice of 10 t/h CaCl2 makes sense, since10 / (10 + 10 + 4.6) is approx. 0.4

Remark on feed:At the end of the work we will be able to tellwhat effort is required to make approx. 1 t/h ofHCl gas, if this flow is given at a concentration, where ordinary distillation must fail.

Feed and Utility Data … Takeout

BRINE + Water

HClExtractiveDesorber

HCl + Water

BRINE

Chilling Medium25% CaCl2, -10°C

Cooling Water32°C

Saturated Steam

Steam Condensate

Cooling Water40°C

Chilling Medium-5°C

Feed is 1 t/h HCl as 18% acid

Extractive agentis 10 t/h CaCl2as 50% aqueous,coming fromregenerator

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

Process System pressure is 1 atmby default.

Utility and other pressuresnot in the focus here.

Evaporator … Takeout

E1: FlashDuty = 1 MWPressure Drop = 0

ACID

25°C

4555.6Water

1000HCl

0CaCl2

BRINE

boiling

10000Water

0HCl

10000CaCl2

Specification

1000 HCl shouldbe kg/h

Pressure is 1 atmby default

Unit E1 is supposed to- mix ACID with BRINE,- heat the mixture up, - evaporate it partially, - and separate V from L, by a

VLE calculation.

Remark on heating duty:When 1 t/h HCl gas is dissolved in water tomake hydrochloric acid with 18 % HCl, a heatflow of 536 kW is generated. The exampleassumes a rough double should suffice to do the reverse.