From Conceptual Design to Operations: Using Mathematical Modeling Tools for Water Optimization in PlantOptimization in Plant

Presented by:

Ms. Jijnasa Panigrahi

Mr. Sharad Sharma

� Mr. Sharad Sharma: Advisory Consultant, Helium Consulting

» 30+ Years Experience in modeling and simulation for critical

processes and products in various industry domain.

» Extensive experience in the field of using technology

software for delivering benefits and improvements in

throughput yield, energy consumption, plant design etc.

About the Authors

throughput yield, energy consumption, plant design etc.

� Ms. Jijnasa Panigrahi: Simulation Consultant, Helium Consulting

» 5+ years of experience in process industries and simulation

modeling

» Experienced in Process simulation and modeling software

includes several modules in the Aspen Engineering Suite.

� Introduction

» About Us

» Consulting Approach Towards Energy and Water

� Overview: Waste Water Treatment, Reuse & Recycle in Industry

� Application of Mathematical Model in Waste Water Treatment, Recycle and Reuse

Contents

Recycle and Reuse

� Case Studies

» Challenges

» Process Description

» Solution Approach

» Modeling Analysis

» Results

� Conclusion

� References

IntroductionIntroduction

Helium Consulting Pvt. Ltd.

About Us

� Team� Our team has immense background in the industry in areas

like Process Modeling, Advanced Planning Systems,

Advanced Process Control and Manufacturing Execution

Systems

� Across team, average experience of team members is 7+

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� Across team, average experience of team members is 7+

years

� Good education background in Engineering, Technology and

Management

� Continuous training Program for all members in diverse

technology areas including Modeling, LP, MES, APC and

related fields to keep abreast of latest technology trends

What we do?

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What we do?

INDUSTRY FOCUSChemicals and Polymers

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Chemicals and Polymers

Power and Utilities

Pharmaceuticals

Metals and Mining

Hydrocarbons

What We Do?- A Domain Perspective

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Our Partnerships

� Technology

� Blue chip technology partners in the area of:

� Planning and Scheduling

� Process Modeling

� Advanced process Control

� Data Reconciliation and Yield Accounting

� Consulting

Services augmentation with selected partners in the area of:

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� Services augmentation with selected partners in the area of:

� Process Modeling

� Supply Chain Implementation Services

� Chemical Engineering Lab Services

� Computational Fluid Dynamics

� Stage 1: Begin with Short Value Assessment Study

� Goals:

� To identify potential projects for improvements in water reuse/recycle

� To identify tools and technologies for achieving the goals

� Put in place a project plan, deliverables and cost for the project

� Duration: 1-2 weeks

Location: Onsite at plant/HQ

Our Approach

� Location: Onsite at plant/HQ

� Team Size: 2

� Stage 2: Actual Project

� Execution of the plan identified in the assessment phase

� Duration: 2-6 months

� Location: Onsite at plant/HQ/Offshore offices in Pune

� Team Size: 2-5

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Consulting Approach- Stage 1: Value Workshop

Open Interviews-

Identification

/review of

Goals/Objectives

1-2 days

Evaluation of

PFD,P&ID, Data

Sheets, Control 1-2 days Sheets, Control

logics & Process Data

3-4 days Workshops for Final

Project Identification

2-4 days

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OVERVIEW OVERVIEW

Waste Water Treatment, Reuse and Recycle in Industry

Water Treatment

• Water Treatment is the process used to make water more acceptable for desired end use.

• Key Pollutant Source: Industrial Waste Water

• Sufferer: Eco System

• Large amount of fresh water is used in the industrial process, hence developing waste water as by-product.

• Increasing rate of Industrial Waste water is much higher in developing countries rather than in developed countries

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Why Recycle Process Water?

Water UseWater Use

Agriculture

Industry

Domestic

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• Ecosystem Protection: Waste Water recycling can help to decrease the diversion of water from sensitive ecosystems

• Prevents Pollution: Decreasing wastewater discharges leads to reducing and preventing pollution

• Higher Profit: More waste water reuse leads to less water in, which means higher profits.

Benefits: Waste Water Treatment Reuse & Recycle

which means higher profits.

• Multiuse: Recycled water is most commonly used for non potable purposes, such as cooling water for power plants and oil refineries, industrial process water for such facilities as paper mills and carpet dyers, toilet flushing, dust control, construction activities, concrete mixing, and artificial lakes

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Application of Mathematical Model in Waste Water Treatment, Recycle and Waste Water Treatment, Recycle and Reuse

Mathematical Modeling

• Mathematical modeling is a way to represent the physical world into mathematical system

• Smaller Funnel of Feasible Configurations

• Fewer experimental work

• Improve Existing Asset

WHY MATHEMATICAL MODELINGWHAT IS MATHEMATICAL

MODELING

mathematical system

• These Computer aided models are use in simulation and optimization to permit a better understanding of the process behavior

• Improve Existing Asset Performance

• Improve Process Quality

• Save Cost & Time

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Steady state and

Dynamic

Simulation

Steady state

and Dynamic

Optimization

PROCESS MODEL

Process

Development

Plant Design

Plant Control

Plant control

system

Process Modeling Tool

Typical Applications of Modeling

Process

Development

Plant Design

Plant control

system

Steady state and

Dynamic

Simulation

PROCESS MODEL

Data

ReconciliationPinch

Analysis

Plant Design

Emissions

Plant Start-

up & Shut-

down

system

design

APPLICATION OF MODELING

Plant Designsystem

design

Pinch

Analysis

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MODELLING HELP YOU TO DETERMINEMODELLING HELP YOU TO DETERMINE

Opportunities for internal re-cycle and reuseOpportunities for internal re-cycle and reuse

Water losses in processWater losses in process

The Identification of maximum water use process pointsThe Identification of maximum water use process points

Application of Mathematical Model in Waste Water Treatment, reuse and recycle

Need of separation of waste water streams to increase the potential for re-useNeed of separation of waste water streams to increase the potential for re-use

Effect of Water reuse & recycle in the processEffect of Water reuse & recycle in the process

Operations that can be connected to recycled waterOperations that can be connected to recycled water

Opportunities for internal re-cycle and reuseOpportunities for internal re-cycle and reuse

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Case study 1 Case study 1

Sour Water Stripper Modeling

• Industry: Oil Refinery (Desulfurization plant)

• Problem: Process water is contaminated chemically prohibiting for industrial uses

• Cause: H2S and NH3 are mixed with process water producing Sour Water.

• Challenge:• Challenge:�Regulating the quality of effluent water�Saving energy�Changing highly concentrated pollutant source to useful

resource�Reduce the chemical contaminants in waste water generated

by chemical plants.�To produce an essentially pure water outlet with less than

300 ppm of sour gases. �Arrive at Process Schema to achieve the same� Improvement to sulfur recovery

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• In general sour water stripper is used in industries to separate sour gas

from the water.

• The sour water contains almost exclusively NH3, H2S, and possibly a

trace of CO2; it is generated by refinery hydro-treating

(hydrodesulphurization or HDS) units.

• High H2S content can make sour water extremely foul, and if the H2S is

Process Description

• High H2S content can make sour water extremely foul, and if the H2S is

not recovered, pollution levels would be completely out of hand.

• A sour water stripping system is used to strip the sour gases: hydrogen

sulfide, ammonia, and carbon dioxide from process effluent

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• Built multiple simulation based model for stripping the acid gasses.

• Evaluated various process schemas including multiple solvents, process

configurations etc.

• Evaluated CAPEX+OPEX for multiple schemas

Solution Approach

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FEED

H2SNH3FLASH

DRUM

FEED

Water

H2S Stripper NH3 Stripper

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• Feed stream split into two smaller stream, one of which is heated and then

fed it to the column.

• The ammonia and hydrogen sulphide contained in the water is released by

the heat and exits the top of the tower.

• Two stage sour water strippers are used to produce a clean NH3 stream

when it has a use or if want to keep the NH3 out of the sulfur plant.

Model analysis

• The stripped water from the tower bottom is returned to the process units

for the reuse.

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• Environmental pollution has been reduced, and economical benefit as well

as CSR objectives have been achieved.

• External Design results were validated and conflicts discussed and

debated

Result

FEED PPM Water FEED PPM Water

Outlet

(PPM)

H2S 1800

292NH3 1300

CO2 1400

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Case study 2 Case study 2

Reducing Contamination Through Process Changes to Reuse Various Process Stream

• Industry: Alumina refinery

• Problem: Dissolved/suspended solids carried into the condensate

• Cause: Poor Flash Tank Performance

• Challenge:• Challenge:

�To mitigate Scaled vapour lines, inoperable heater valves wear etc.

�To produce good Condensate to be used in plant

�To improvise the waste water reuse.

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• Bauxite ore wet ground to size appropriate for extraction.

• Alumina extracted from bauxite by digestion in caustic soda at elevated temperature.

• Alumina-rich bauxite slurry cooled down to atm pressure in flash train

Process Description

• Heat exchange with re-circulating spent liquor

• Cooled slurry clarified and washed:

�remove un-extractable materials out of circuit, to residue

�Recover associated soda.

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Solution Approach

• A thermodynamic model based flow sheet was developed

• Various Flash models were added in the computer simulation model and multiple scenarios were tested.

• A modified condensate system was developed.

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Flow sheet

Q

STF1

Q

SXF1

S22

FT2 FT1

MULT

Flash Vapour

Flash Tanks

LTH1

CXH1

LTH2

VTH1VTH2

CXH2

CXH3

BAD-COND

GOODCOND

HT1HT2

Heaters

Bad Condensate

Good Condensate

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Model analysis

• Carryover is related to vapour velocity and equipment design, which are not easily alterable in an existing plant. The situation is made worse when one stage has to carry the burden of another that needs to be taken out for maintenance

• Re-distribute the vapour loads or, alternatively, reduce flow, to minimise carryover.

• If all flash tanks do not have poor performance at the same time, some of the condensate may be recoverable, though this may not be possible of the condensate may be recoverable, though this may not be possible with the installed condensate routing system.

• Hence additional equipment or checks have been considered to minimise carryover under various scenarios.

• As a result we Designed a modified condensate system, separating good condensate from bad condensate in additional condensate flash pots, and routing the former to the boilers.

• Models have been used to look at options to reduce carryover and piping wear, and improve condensate quality.

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• Energy Saving: Reduce energy and the need for make-up condensate.

• Meticulous Off line Study: The model gave us the ability to consider all

these opportunities together or one or more at a time, so that the

interactions were accounted for.

Further applications of mathematical modeling include:

• Reduction of alumina/soda/liquor to residue

Results

• Reduction of alumina/soda/liquor to residue

• Condensate re-routing and re-use

• Wash-water re-use and optimisation; concentration targeting

• Managing the dilution-evaporation balance across the plant

• Systematic analysis of contact heating

• Improving integration of co-gen plants with process.

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Case study 3 Case study 3

Water Network Optimization

• Industry: Alumina refinery

• Problem: Multiple water streams in the plant which is believed to

be re-usable

• Cause: Process water contamination

• Challenge:

�To evaluate possibility of water regeneration and reuse

�Minimise fresh water inflow

�Minimise discharge of waste water

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Process Description / Flow Sheet

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Solution Approach

• Study for evaluation of Water PINCH

• Work to be integrated with previous work on Heat PINCH

• Cost - benefit analysis to determine feasible approach to target

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Model Analysis

�Targeting

Heat Integration Water Integration

�Synthesis

�Conceptual Design

�Mathematical Programming

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� Simultaneous water and heat integration could achieve upto:

- 20% reduction in soda loss per ton alumina

- 20% reduction in energy consumption per ton alumina

Further applications of mathematical modelling include:

Results

� Retrofits - geographical, process, or design constraints.

� Where there is uncertainty and flexibility of contaminant loads

� Multiple species/contaminants/properties

� Simultaneous application of process integration, energy analysis and optimisation

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Conclusion- Mathematical Modeling

• Mathematical modeling is a way to represent the physical world into mathematical system

• Smaller Funnel of Feasible Configurations

• Fewer experimental work

• Improve Existing Asset

WHY MATHEMATICAL MODELINGWHAT IS MATHEMATICAL

MODELING

mathematical system

• These Computer aided models are use in simulation and optimization to permit a better understanding of the process behavior

• Improve Existing Asset Performance

• Improve Process Quality

• Save Cost & Time

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References

� Aspen Technology, HX-Net Tutorial, 2004.

� Aspen Technology, Support Website, 2012

� Kuo W.C.J., and R. Smith, “Design of Water-Using Systems Involving Regeneration”, Trans Ichem (part B), 76(1998) 94-114.

� Prakash, R., and U. V. Shenoy, "Targeting and design of water networks for fixed flowrate and ixed contaminant load operations," Chemical Engineering Science, 60 (2005) 255-268.Engineering Science, 60 (2005) 255-268.

� Ullmer, C., N. Kunde, A. Lassahn, G. Gruhn, K. Schultz, “WADO : Water Design Optimisation - Software for the Synthesis of Process Water Systems”, Journal of Cleaner Production, 13 (2005) 485-494.

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