how to study and to optimize continuous industrial gas...

How to study and to optimize continuous industrial Gas-Liquid-Solid reactor under hydrogen presssure. Nextlab 2014

April 3rd 2014

E Lecomte-Norrant

GPS/ ITS Dr

NEXTLAB 2014 IFPEN April 3rd Rueil Malmaison

ן Context of the problem: a complex G/L/S continuous reactor...

ן Data acquisition: development of tools Kinetic rate

Hydrodynamic data by radioactive tracers

Volumetric ratio of each phase by gamma rays

Profile of concentration of raw material and H2 in liquid phase

ן Determination of gas/liquid mass transfer coefficient with the validation of model

ן Conclusion: Optimization of operating conditions

Continuous Gas-Liquid-Solid industrial reactor under H2.

2


AGENDA

Continuous Gas-Liquid-Solid industrial reactor under H2 3

Context: industrial reactor...

Since yesterday, a lot of sciences with new tools concerning the “ laboratory of the future” to develop our future industrial processes...

BUT Do not forget...

We have some old industrial processes which work for more than 20 years , and no one knows exactly how they work.

My target is How to improve or to solve some problems on these chemical reactors?

So development of tools to use directly on existing industrial are required, by taking account all safety conditions.

It is the industrial reality....for old processes.

I want to present to you one of these examples.

A complex G/L/S continuous reactor...

4

Principe of the industrial reactor

I

Gas/Liquid/solid Bubble column N°1

Gas/Liquid/solid Bubble column N°2

Liquid/solid Columns N° 1 & 2

Cyclone

Settling tank

H2 H2

Raw material catalyst


Cyclone

Settling tank

Gas/Liquid/solid Bubble column

Liquid/solid column

Recycle of H2

H2

Raw material Catalyst

Product

Old catalyst

A complex G/L/S continuous reactor... 5

How to optimize operating conditions?

What we know?

• The inlet flow rate of H2, raw material with the outlet flow of final product

• The inlet/outlet temperatures of the jacket and one temperature in the reactor

• The size and design of all equipment.

What we do not know? But we must know

• The velocity of each phase

• The volumetric ratio of each phase

• The axial dispersion of each phase

• Gas-liquid mass transfer flux

• Liquid-solid mass transfer flux

• Concentration of raw material, intermediates and by-products

• the kinetic rate of main reactions with by-product reactions

in each part of the reactor


G/L/S reactor : Kinetic rate 6

Runs in laboratory in batch way..

2 main consecutive reactions: Di-nitrile to Di-amine

DN + 2 H2 - MN

MN + 2H2 DA

Langmuir Hinshelwood model

DN---> MN : Rm1 = ] [ 20.5

H.sHMN.sMNDNsDN

sH,HDNsDN1

] )C (K 1 C K C K [1C K C K k

+∗++

MN---> DA : Rm2 = ] [ 20.5H.sHMN.sMNDNsDN

sH,HsMN,MN2

] )C (K 1 C K C K [1 C K C K k

+∗++


kl = 3475 e -42900/RT kmol DN/kg/s ∆E1 = 42.9 kJ / mol k2 = 6895 e -45619/RT kmol MN/kg/s ∆E2 = 45.6 kJ / mol KDN =9.1 e+170/RT m3/kmol ∆ΗDN = -0.17 kJ/mol KMN =66.2 e-6641/RT m3/kmol ∆ΗMN = 6.6 kJ/mol KH =2.5 e+9080/RT m3/kmol ∆ΗH = -9.1 kJ/mol ∆H : Heat of adsorption of reactants.

A complex G/L/S continuous reactor... 7

How to optimize operating conditions?

What we do not know? But we must know

• the kinetic rate of main reactions with by-product reactions

• The velocity of each phase

• The ratio of each phase

• The axial dispersion of each phase

• Gas-liquid mass transfer flux

• Liquid-solid mass transfer flux

• Concentration of raw material, intermediates, by-products and H2 in Liquid phase

in each part of the reactor

How to get data?

• Runs in lab

• Radio active tracers on each phase

• To check

• Tool made home ...


Tool box... 8

Radio active tracers to measure...

•Velocity of each phase

•Volumetric Ratio of each phase

•Axial dispersion of each phase

Phase Tracer Half life Energy Mass injected

Gas phase Argon 41 110 mn 1.29Mev 12ml Nm3

Gas phase Krypton 79

34 hours

0.511Mev 12ml Nm3

Liquid phase

Br82

(NH4Br) 36

hours 1.47;0.78;0.62;0.5

5Mev

0.2-0.5g

Solid phase

Ni65 2.56 hours

1.49; 1.11 Mev

8-10g


Choice of tracers

Work done with the collaboration of CEA

6

4

8

5

3

1

9 Outlet of product

7

10

2

Solubility of gas tracer to compare with H2 solubility 9

Bunsen Coef.(ml TPN / L/ bar)

H2 31 49

Ar 92-96 89-91

Kr 250 -256 192-193

T= 20°C T= 80°C

Krypton is 2 more time soluble that Argon in our mixture

Results with radio active tracers... 10

Probe N°3

Probe N°4 Probe N°5 Probe N°6

Probe N°3

Probe N°1

Probe N°4 Probe N°5 Probe N°6

Liquid phase

Gas phase


Results with radio active tracers... 11


Probe N°8: top of the L-S column For liquid tracer and solid tracer

Probe N°10 Outlet of product

Treatment of data : Analysis of the two signals inlet and outlet; classical method

12

Algorithm of the software:.

Reading of inlet and outlet data with treatment of data to remove parasites

To transfer data in FOURIER space

Réinitialisation . Initialization of Pe and τ in the transfer function. of Pe and τ

Calculation of outlet curve in FOURIER space to get the outlet theoretical curve

Comparison of the experimental outlet curve with the calculated theoretical curve with the less square method to minimize the residues

Good values of Pe and τ


Results Radio active tracers for G/L/S bubble column

Reproductibility:


Run Tracer ProbesVelocity

(m/s)

Diffusion Coefficient

(m2/s)

Peclet Number

N°1 Argon 41 [ 3 - 6 ] 5.1 0.5 168N°2 Argon 41 [ 3 - 6 ] 5.1 0.5 170N°3 Krypton 79 [ 3 - 6 ] 5 0.56 160N°4 Nickel 65 [ 1 - 6 ] 4.47 0.27 300N°5 Brome 82 [ 1 - 6 ] 4.45 0.25 320

Comments • Reproducibility has been checked

• Velocity of liquid phase and solid phase are the same

• Small difference between gas velocity and L/S Velocity

• Plug flow reactor can be taken as model


Results Radio active tracers for L/S column

Comments

• Precision on Diffusion coef. is not very precise (< 20%)

• Precision on velocity is accurate (< 2%)

• Velocity of liquid phase and solid phase are close

• Small difference between L/S Velocity and Gas velocity

• Plug flow reactor can be taken as model

Run TracerVelocity

(m/s)

Diffusion Coefficient

(m2/s)

Peclet Number

N°1 Argon 41 3.6 0.14 450N°2 Argon 41 3.6 0.19 387N°3 Krypton 79 3.75 0.2 387N°4 Nickel 65 3.83 0.18 550N°5 Brome 82 3.85 0.2 394


Results Radio active tracers for cyclone

Comments

• Cross flow in cyclone between the 2 columns

• Residence time of liquid or solid phase is 1.06s

• A small flow goes to decanter : Centrifuge effect...

Cyclone

G-L-S Column

Solid : 25%Liquid: 28%Solid : 68%

Liquid: 68%

Solid : 7%Liquid: 4%

Solid : 100%Liquid: 100%

L-S ColumnL-S Column

To summarize... With radio active tracers... 16

JAMBE MONTANTE

ε gaz= 0.266 Qgaz= 345 m3/h ε liq= 0.71 Qliq= 830 m3/h ε sol= 0.023 Qsol= 26.9 m3/h Da gaz= 0.50m2 /s u gaz= 5.1m/s Da liq= 0.23m2 /s u liq= 4.5m/s Da sol= 0.27m2 /s u sol= 4.5m/s

JAMBE DESCENDANTE

ε gaz= 0.09 Qgaz= 80 m3/h ε liq= 0.88 Qliq= 796.8 m3/h ε sol= 0.026 Qsol= 25 m3/h Da gaz= 0.15m2 /s u gaz= 3.65m/s Da liq= 0.2 m2 /s u liq= 3.85m/s Da sol= 0.12m2 /s u sol= 3.85m/s

Q gaz = 7000Nm3/h Q ADN = 32.5 Tonnes/h Q liq = 2.3 m3/h

Q HMD = 70 Tonnes/jour

DECANTEUR Qliq= 66.3 m3/h Qsol= 3.76 m3/h u liq= 2.1mm/s

Retour Qliq= 27 m3/h

Qsol= 1.68 m3/h u liq= 3.83m/s

Pot de soutirage

CYCLONE τsol=τliq=1.06s

ε Taux de rétention τ Temps de séjour Da Dispersion axiale u Vitesse interstitielle Q Debit

G-L-S Column

L-S Column

Product

Q DN Q Catalyst

Q H2

Back to GLS column

Decanter

ε : Volumetric fraction, τ Residence time Da : Axial dispersion U : velocity

Decanter


To check the global density by gamma rays...why?

Several same reactors with a different behaviors: A shutdown of one reactor must be done each 6 months (to compare with others : 18months) to clean the reactor : problem of heat transfer.

Difference of behavior when I took samples to measure raw material concentration and Soluble H2. (See later)

The intensity I of gamma ray captured by the detector, through a material of a thickness x and a density D is I= I0 e-(µ * x * D)

Work done by Process Vision service

ן Results : data of global density by gamma rays as function of 3 different flow rate of H2 ( close to Nominal flow rate)



Probe Probe

0.7 N 1 N 1.2 N 0.7 N 1 N 1.2 N

1 0.89 0.75-0.96 0.88 1.04 1 1.2 12 0.98 0.87 0.9 1.12 1.12 1.1 23 0.98 0.92 0.9 1.1 1.1 1.09 34 0.94 0.9 0.88 1.13 1.15 1.13 45 1 0.91 0.85 1.15 1.17 1.13 5

7 0.93 0.7 0.778 1.04 1.04 1.01 0.97-1.04 0.98-1.03 0.98-1.04 109 0.82-1.09 0.85-1.07 0.84-1.04 1.14 1.16 1.12 11

Density of Bubble column Density of L-S ColumnFlowrate % Nominal flow N Flowrate % Nominal flow N

Comments • Density of G/L/S is lower than Density of L/S column • To check the accuracy of data


Results concerning global density by gamma rays of the reactor which works differently...

Comments

• Difference of density: different values between upright and horizontal pipe.

• Cyclone works like a spillway which induces a bad separation of Gas from L/S phases;

• Low difference of density between G/L/S column and L/S column, which reduces the velocities of each phases and increases clogging.

Probe Probe

1a upright 0.6 0.69 upright 1a

1a Horizontal 0.67 0.73 Horizontal 1a

1b upright 0.73 0.69 upright 1b

1b Horizontal 0.8 0.78 Horizontal 1b

Density of mixture at te top of the columns

Density of mixture at te top of the columns

ן How can we explain this problem and How to solve it?

20

Outlet of product

After several weeks , I discovered that a small pipe in the receipt tank of product, has been cut at the entrance of the tank by the maintenance...

We add a pipe with a length of 1 meter and we solve the problem: we equilibrate the level of liquid in cyclone....


Profile of concentration of raw material and H2 in liquid phase

PPP

Event

Bougie Filtrante

Purge de la prise Echantillon

Bac de récupération

Réacteur

Cellule de mesure

Cellule de séparationLiquide du Gaz/Solide

From Reactor

Filter

Tank to separate Solid and gas from liquid phase

Cell to measure

To purge the sample line from reactor

Tank filled up of water for wastes

Tool made home..

Sample points on the industrial reactor.... 22

Top of G/L/S Column

Top of L/S Column

Different points in the decanter

Bottom of L/S Column

Results of DN and MN concentration at the top of G-L-S Column as function of time to take

samples

23

MN DN

Time ( second)

Con

c D

N o

r MN

(ppm

)

X 1000

24 Results of H2 concentration as function of T at different samples points

.

Q gas = N Nm3/h Q Product nominal

Top G/L/S

Top L/S Column

Bottom L/S column

Top of Decanter

To model the industrial reactor: Plug flow reactor 25

Parameter to optimize : Gas/Liquid mass transfer: Kla (s-1)

Evolution of concentration of DN and MN in each part of reactor

26

1)

G/L/S Column L/S Column Cyclone

Decanter

Con

c of

DN

& M

N (

ppm

) X

1000

MN

MN

Between inlet DN and H2

Evolution of concentration of Soluble H2 in each part of reactor

27

G/L/S Column L/S Column Cyclone

Decanter

Length of reactor (m)

ן Some surprising results...

ן Comments In the L/S column, it is not a Gas/Liquid mass transfer but a

Solid/liquid mass transfer of H2: desorption of H2 from Ra Ni catalyst to the liquid solution; ( Shuttle effect well described in the literature) Be careful to get enough soluble H2 in the liquid phase to avoid

deactivation of catalyst

Determination of Gas/liquid mass transfer 28

Top of G/L/S column

Top of L/S column

Bottom of L/S column

Bottom of Decantor

Error % (H2c-H2m)/ H2c 11% 0.30% 9% 2.50%

G/L/S column

Cyclone L/S column Decanter

Kla (s-1) 0.6 0.4 0.25 (*) 0.02 (*)

Ref Chemical Engineering Science, Vol 47, N°13/14. Pp3597-3604, 1992 By E Lecomte , C.MATHIEU. H. DELMAS and J.JENCK

ן Shuttle effect...

Determination of Gas/liquid mass transfer 29

Gas Bubble

NiRa

Interface Gas/Liquid

Diffusionnel layer

Liquid bulk

Gas Adsorption on solid Particule NiRa

Gas Desorption in the liquid bulk

ן We achieve our target:

To understand the working of industrial reactor

By building the model, we optimize operating conditions to increase the productivity by 10-15% on each reactor in safety way.

Main modification: to introduce raw material and new catalyst close to H2 introduction

We solve the malfunctioning of one reactor.

Thanks to • the plant manager who allowed me to take samples in continuous way.... • CEA for radio active tracers • Process vision service for gamma rays

Conclusion 30

Questions? 31


Thanks!

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