06_troubleshooting of distillation columns using aspen plus_aritra_ril

Presented By:

ARITRA CHAKRABARTY SENGUPTA

Simulation and Modelling Group, RTG, RIL

TROUBLESHOOTING OF DISTILLATION

COLUMNS USING ASPEN PLUS

DISCLAIMER

Any statement, opinion, prediction, comment, or observation made in this

presentation/publication are those of the presenter/author only and in no condition

should be construed necessarily representing the policy and intent of Reliance

Industries Ltd. (RIL).

The information presented herein are of the presenter/author’s own and in no way

RIL attracts any liability for any inconsistency or irregularity in terms of the accuracy

completeness, veracity, or truth of the content of the presentation/publication. In

addition, RIL shall not be liable for any copyright infringement and

misrepresentation for the presented content as the content is presumed in good

faith to be a creation of presenter’s/author’s own mind.

The scope of this presentation/publication is strictly for knowledge sharing

purposes and not necessarily to provide any advice or recommendation to the

audience/readers. Any endorsement, recommendation, suggestion, or advice made

by the presenter/author shall be in his personal capacity and not in professional

capacity as an employee of RIL. Any person acting on such endorsement,

recommendation, suggestion, or advice will himself/herself be responsible for any

injury/damage. © Reliance Industries Ltd., 2016

Dhirubhai H. Ambani Founder Chairman Reliance Group

• 1966- Establishes Textile mill in Naroda

• 1977- Public share offering Raised money

from public offerings oversubscribed 7X

• 1982- Builds fiber/filament plant in Patalganga

• 1995- Builds Polyolefin plants at Hazira

• 1997- Builds multi-feed cracker at Hazira

• 1999- Builds Jamnagar refinery

• 2002- Acquired IPCL a state run company

• 2008- Builds JERP refinery at Jamnagar

• 2009- Begins KG D6 gas production

• 2013- Builds PBR/SBR plants at Hazira

• 2014- Builds PTA plant at Dahej

• 2014- Builds PET plant at Dahej

RIL - BRIEF INTRODUCTION

© Reliance Industries Ltd., 2016

RELIANCE PERFORMANCE

Performance; (For Year 2014-15)

$ bn

Revenue/turnover 62.2

Exports in refining

product 32.5

EBDIT 6.3

Cash profit 5.1

Net profit 3.8

Segment performance in Rs (Crore)

Oil & gas Refining Petrochem Others

Revenues 11,534 339,890 96,804 5,507

EBDIT 3,181 15,827 8,291 1,250


Global Indian company

PBR/SBR

(Figures in ‘000 tonnes per annum)

PET


PX

(Figures in ‘000 tonnes per

annum)

Ethylene


PTA


PE


MEG

(Figures in ‘000 tonnes per

annum)

Jamnagar

Dahej Hazira Silvassa

PFY/PTY


GROWTH PLANS


Major expansion in petrochemicals

What is Good for India, is Good for Reliance

SUCCESSFUL BACKWARD INTEGRATION FOR FEEDSTOCK SECURITY IN PET & POLYESTER PRODUCTION


INTRODUCTION

ABOUT SIMULATION AND MODELLING GROUP: We are a close knit group headed by Dr. Karuna Potdar. Our work includes extension of Simulation Related help across all sites of RIL. We prepare models of different Process Units, which are used for trouble-shooting, de-bottlenecking etc. We are also involved in process development and we work with different verticals in close conjugation.

SIMULATOR AS TROUBLE-SHOOTING TOOLS: Simulation Tools including Aspen Plus are good for getting to the root cause or any unprecedented anomalies in the process units. However it should always be remembered that it is a tool and it is important to give correct inputs and later correct analysis of the results is required to enhance its efficiency of usage.

ASPEN PLUS AS A TROUBLE-SHOOTING TOOL: In RIL, ASPEN PLUS is the most frequently used tool for Simulation and Trouble-shooting. It’s user friendly interface and reliability of the obtained results, makes its use extensive in the organisation.

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PROBLEMS:

1. VADODARA MANUFACTURING DIVISION, BUTADIENE PLANT DEGASSER PERFORANCE REDUCTION ISSUE.

2. PATALGANGA MANUFACTURING DIVISION, LAB PLANT, PARAFFIN COLUMN PERFORMANCE REDUCTION ISSUE.

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PROBLEM 1: VMD BUTADIENE PLANT

9

CC-31

Compressor

K.O. DrumDegasser feed

flash drum

Final Column

Propyne

Column

1:3

BD

Main WasherRUP RLP

After WasherAcetylene

washer

Degasser

MX-C4

Feed

BUTADIENE FLOW DIAGRAM

V A to

Flare

13-505

V-31V-22

C-22

C- 45C- 41

C- 24

13-504

13-503

13-502

P 33

CIS

C4R


PROBLEM 1:

Introduction:

The Degasser column of Butadiene Plant in VMD is a packed column with six beds.

It is required to maintain solvent quality.

By Design all the Beds had same packing.

In April shutdown some packing were changed.

After start-up column performance deteriorated.

Temperature profile changed and PDI increased

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PROBLEM 1:

Trouble-shooting using Aspen Plus: Given to the seriousness of purpose a team started working towards the issue.

Aspen Plus simulations were done both in Equilibrium and in Rate-based models for the design case.

In the Equilibrium case, the column was modelled as a tray column and Murphree efficiency was tuned

As this column is an absorber, to have a more realistic approach we did the simulation in Rate-Based mode and Interfacial Area factor, Mass transfer coefficient factor and heat transfer coefficient factor were tuned.

However both the models gave very similar results.

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PROBLEM 1:

Trouble-shooting using Aspen Plus: contd..

The same tuned models were used to evaluate the disturbed case.

A considerable reduction in Murphree Efficiency/Mass Transfer coefficient factors were observed.

Depending on this inference, the column was taken under shutdown.

Heavy fouling was observed in the bottom bed and this was the reason for the reduction in efficiency in both simulation and plant.

Probably for an operation as polymer/dimer formation prone as this, any seed which might be seated on the packing beds can result into accelerated polymeric growth under favorable conditions.

Aspen also indicated the malfunction of some temperature indications which were rectified.

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PROBLEM 1: INFERENCE

THE DECISION OF SHUTDOWN AND CLEANING/REPLACING THE PACKING

MATERIAL OF THE BOTTOM BEDS HELPED MAINTAINING RELIABLE SOLVENT QUALITY,

WHICH IN TURN IS IMPORTANT FOR UPSTREM EXTRACTIVE DISTILLATION COLUMNS, TYPICAL

OF BUTADIENE PURIFYING UNITS.

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PROBLEM 2: BLOCK DIAGRAM OF LAB PLANT

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PROBLEM 2:

Introduction:

Paraffin Column is Heart of any Linear Alkyl benzene (LAB) Plant.

It is a packed column operating under vacuum.

The Top product is recycle paraffin & the Bottom product of this Column is the Final LAB Product of Plant.

After May’15 turnaround of LAB Plant, when Plant was started, both the Top and Bottom Products of this Column were observed out of specification limits.

No activity was carried out in this Column during the turnaround.

Operation team adjusted reflux, reboiler duty etc but specs could not be met. 15


PROBLEM 2:

Trouble-shooting using Aspen Plus:

a. A simulation model of the column was available, tested for design case and stable operation case.

b. A dedicated team went to site for quick access of operating data.

c. The validated model was used to match the disturbed scenario, tuning Murphree Efficiency.

d. An incredible reduction of efficiency indicated that some unprecedented problem had occurred inside the column.

e. Shutdown was taken the following day largely on the basis of simulation results to inspect the column internals.

f. Certain internals showed deviation from design.

g. These issues were rectified.

h. After start-up column performance was restored.

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PROBLEM 2: INFERENCE

Both Top and Bottom Product of the column were brought within specifications after shutdown. Finished

LAB Product met the quality of saleable Product.

Reduction in LAB content in recycle paraffin by ~93% aided in preventing the loss of Rs.14.6 Lacs / Day by

avoiding the loss of high value LAB Product in recycle paraffin stream, which is a permanent loss.

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Aspen as a trouble-shooting tool :

Aspen Plus has an easy and understandable user interface which makes it a good tool even if we need instant results like the discussed problem 2.

However it is better to have validated models of process units made, such that any unwanted situation can be easily evaluated.

The reliability of the results is well explained through the discussed cases.

There is facility of modelling the columns in both Equilibrium and Rate based approaches and helped cross-checking of Problem 1 results.

The constant help through support website, emails and other modes of communication with the experts of the Aspen team makes solving issues easier and quicker, and is highly appreciated.

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THANK YOU

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06_troubleshooting of distillation columns using aspen plus_aritra_ril

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