Engineering 101

© Whitewater Limited 2012

Engineering Design Considerations

Richard Hill

Whitewater Limited

Consulting Engineers & Scientists

Aims and Objectives

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To be able to calculate resin volumes and vessel sizes To appreciate hydraulic effects To understand regeneration sequence

– counter flow regeneration systems – stratified bed operation – mixed beds

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© Whitewater Limited 2012

To be familiar with vessels and internals To understand EDI

Process Design Parameters

regeneration level (eq/l)

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Regeneration Ratio = exchange capacity (eq/l) flow rate (m3/h)

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Hydraulic loading (BV/h) = resin volume (m3) 1

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© Whitewater Limited 2012

EBCT (h) = hydraulic loading

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Turndown ratio

Maximum flow rate (m3/h) Minimum flow rate (m3/h)

Process Design Parameters

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The volume of treated water produced per cycle (Q m3) by V litres of resin with capacity Ceq/l treating water with ion exchange load L meq/l is :

Q = (F x T) = (V x C)/L

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© Whitewater Limited 2012

The resin volume is given by:

V = (F x T x L)/C

where the treatment plant operates for T hours between regenerations at F m3/h

Hydraulic Design

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For a resin of capacity C eq/l treating a water with ionic concentration L meq/l at a flow of Q m3/h the run time, T h, is:

T

V C Q L

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where V is the resin volume in litres. Now if the maximum hydraulic loading is W BV/h then:

W

Q 1000 V

and

T

C 1000 Wc

Hydraulic Design

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So for a typical minimum run of 8h on an anion resin of capacity 0.6 eq/l at 30 BV/h: L 2.5 meq/l

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© Whitewater Limited 2012

If the anion concentration is greater than 2.5 meq/l the run time will be shorter than the minimum 8 h. If the concentration is less than 2.5 meq/l, the resin volume will be determined by the maximum hydraulic loading and this will set the run time.

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Hydraulic Design

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Head loss through resin,

h =...