water conservation_rm mathur

8/8/2019 Water Conservation_RM Mathur

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& ,e n t ra l P u lp P ap er Re se a rc h I n st i t ut e Sa ha r a np u r

Water Conservation In Pulp & Paper IndustryThrough Innovative Water Management &

Modeling Techniques.

R. M. Mathur, B.P. Thapliyal, A.K. Goel

Central Pulp And Paper Research InstituteP.O.Box. 174, Saharanpur


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Pulp and paper industry is one of the major water

consuming industries.Water is used for a variety of processes and gets

contaminated during processing with raw

materials,chemicals, by-products & residues.Treatment of contaminated wastewater has

always been an expensive & technically

challenging subject.


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Water Consumption In Indian Paper Mills

Raw Material Products Water Consumptionm3/tBamboo Writing/Printing Paper

100-120

Wood+Bamboo Writing/Printing Paper 90-125

Wood+Bamboo Writing/Printing Paper

Unbleached varieties

80-120

Wood+Bamboo+RCF News print 95

Agro Residues Writing/Printing Paper 100

RCF News print/ writingPrinting

35

Market Pulp Speciality Paper 90


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Bleaching

30%

Paper

Machine

25%

Pulping

14%

Chemical

Recovery

10%

Power House

6%

Stock

Preparation

4%

Others

11%

Typical Water Consumption in Wood/ BambooBased Mill


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Water management techniques can prove to

be highly effective as they enable efficient

usage of water with considerations of

reuse, recycle and

regeneration opportunities.


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Process Integration

The application of methodologies aimed at

designing/modernizing an Industrial Facility by

optimizing its various constituent units rather

than improving each individual unit by itself.


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Process Integration Methods

Classical pinch based

Mathematical programming based


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Graphical technique to minimize fresh waterflow

An extension of the pinch analysis

technique for heat integration.Water surplus diagrams are utilized to

target water requirement.

Pinch Based Approach


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Water Pinch Composite Curves

Each water related

process operation

considered as having

water inputs and

output streams and

composite of water

demand (Input) and

water sources (Output)

can be constructed.

Concen

tra

tio

n

Water Flow

Waste water

Fresh Water

Water Pinch

Water Demands

Water Sources

Purity

Not suitable for multiple contaminant systems


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The pinch point ( pinch concentration and pinch

mass load) is calculated by application ofComposite Table Algorithm (CTA).

A system of equations is solved with constraints to

get values for various water streams.

A Network is generated by applying NearestNeighbor Algorithm (NNA)

Network of all possible matches is created and

the system is optimized for minimum fresh water

requirement based on capital/operating

expenses.

Mathematical Programming Approach


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Provides a robust way of water network design.

Provides insight into water targeting with a

consideration of recycle, reuse & regeneration.

Advantages of

Mathematical Programming Approach


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Basic Network Structure

A basic integrated water network consists of a set of

water using and water treating operations.

Each water using operation demands a certain quality

and quantity of water to satisfy its process needs.

This demand may be fulfilled by mixing fresh water with

effluent streams from other water using operations and

regenerated water.

The process outlet streams may be used to satisfy the

demand of other operations, sent to treatment units or

discharged without treatment.


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Process

C P in C P out

C Water out C Water in

C P in

C P out

C Wout

C W in

m, Mass flow rate

Conce

tra

tio

n

Unit operation mass flow


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Mill Details:-

Production 75,000 tpaProducts - Printing and writing papers

Raw materials - hardwood and bamboo , ratio(84:16)6 paper machines

3 stationary batch digesters

Pulp is bleached by using C/DEopD1D2 bleaching

sequence.

CASE STUDY


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The study was carried out for two contaminants(TS & COD) in the bleach plant for reuse &

recycle options.

A complete water balance of the pulp mills wasprepared using online & portable flow meters.

The water samples from various streams were

characterized with respect to their pollution load.

METHODOLOGY


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Water Balance Flow Diagram for Mill

( All Figures in m3/hr)


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Data Extraction:

All operations assumed to be fixed contaminant

(FC) and fixed flowrate operations type. Thelimiting contaminant levels are fixed at 10 %

above the current values.

Restriction on re use of water streamsAll matches prohibited by pH are

disallowed.

Order and flowrate from one processto another is maintained


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Fig. Extracted Flow Diagram

368 368

1854 2970

403 403

1190 2081

367 367

1037 1910

373 373

990 1447

847847

656 656

CD

Pulp washing

EOPPulp washing

D1

Pulp washing

D2

Pulp washing

DeckerPulp washing

D 1

D 2

D 3

D 4

D 5

S 1

S 2

S 3

S 4

S 5


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Composite Table Algorithm..m...C - Cmin

Flow

Concentration,

ppm

Net Flow,

t/hr

Load

Kg/hr

CumulativeLoad, kg/hr

(m) Slope

d 847 600 0 0 0 0

s 847 656 847 47.4 47.4 72.3

d 373 990 0 0.0 47.4 47.9

d 367 1037 373 17.5 65.0 62.6

d 403 1190 740 113.2 178.2 149.7

s 373 1447 1143 293.8 471.9 326.1

d 368 1854 770 313.4 785.3 423.6

s 367 1910 1138 63.7 849.1 444.5

s 403 2081 771 131.8 980.9 471.4

s 368 2970 368 327.2 1308.0 440.4

3000 0 0.0 1308.0 436.0

Pinch pointPinch LoadPinch conc.

Flow = FlowDemand - Flow Source

Flow x ( C2 C1)/1000


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Limiting Composite Curve

3000

2500

2000

1500

1000

500

250 500 750 1000 1250 15000

Contaminant Load, kg/hr

C

on

tam

ina

ntC o

ncen

tra

tion,

ppm

Limiting Composite Curve

Water Composite curve

Pinch LinePinch Concentration

Pinch Load


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Nearest Neighbour Algorithm

Sources which are immediate higher/ lower

in concentration for a demand are mixed in

ratio determined by mass balance to

satisfy the demand.

If the required flow rate is not available fora source, than whatever is available of that

source is used completely & next neighbor

is considered to satisfy the demand.


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Nearest Neighbour Algorithm

The mass balance equations are-

FSK , DP + FS(K+1), DP = FDPFSK , Dp CSK +FS(K+1),DP CS(K+1) =FDP CDPWhere

F&C are flowrate & concentration

SK & S(K+1) are immediate cleaner& dirtier

sources ( Nearest Neighbour)

DP is the particular demand.


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Proposed Water Balance Network for Mill -1


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Results for Mill I

Particulars Min. Fw UnitsMin. Fresh WaterConsumption before PI

191 m3/hrMin. Fresh Water after PI(considering TS and

COD as contaminants)

121 M3/hr

Fresh Water Saving % 36 -


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& ,

HANK YOU

water conservation_rm mathur

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