Danfoss SWRO Service guide

Service Guide

SWRO plants working with

APP pumps and iSave ERDs

Trouble shooting guide

hpp.danfoss.com

Service Guide | APP pump and iSave ERD in SWRO plant

Table of Contents	Table of Contents
	1.	Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. .	.	2
	2.	Seawater desalination system - terms of understanding . . . . . . . . . . . . . .	.	.	.3
	3.	What does the APP high-pressure pump do . . . . . . . . . . . . . . . . . . . .	.	.	.4
	4.	What does the iSave ERD do . . . . . . . . . . . . . . . . . . . . . . . . . . .	. .	.	5
	5.	What does the LP-out flow control valve do . . . . . . . . . . . . . . . . . . . .	.	.	.6
	6	Trouble shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	.	.	.7
	6.1	Permeate production decrease . . . . . . . . . . . . . . . . . . . . . . . . . .	.	.	.7
	6.2	Membrane feed pressure decreases / increases . . . . . . . . . . . . . . . . . .	. .	.	8
	6.3	LP-in seawater flow decreases / increases . . . . . . . . . . . . . . . . . . . . .	.	.	.9
	6.4	LP-in seawater pressure decreases / increases . . . . . . . . . . . . . . . . . . .	.	.	10
	6.5	LP-out brine water flow increase . . . . . . . . . . . . . . . . . . . . . . . . .	. .	. 11
	6.6	High Amp / overload at iSave VFD . . . . . . . . . . . . . . . . . . . . . . . .	. .	.12
	6.7	High Amp / overload at APP pump VFD . . . . . . . . . . . . . . . . . . . . . .	.	.	13

	1. Introduction	This document gives a good understanding how		Information specific on the individual APP and
		the SWRO plant works together with APP pump		iSave must be found in the Data sheets or Oper-
		and iSave energy recovery device.		ating guides (IOM).
		•	Explain the function of each main product.
		•	Explain how the SWRO plant reacts when
			main products get adjusted.
		•	Trouble shooting guide with possible causes
			and actions.

APP pumps

Danfoss APP pumps are positive displacement pumps with axial pistons that move a fixed amount of water in each cycle. Flow is proportional to the number of input shaft revolutions (rpm). Unlike centrifugal pumps, they produce the same flow at a given speed no matter what the discharge pressure is.

The design of the APP pump ensures lubrication of the moving parts by the fluid itself.

iSave energy recovery device

The iSave consists of an isobaric pressure exchanger, a high-pressure positive displacement booster pump and an electric motor.

The isobaric pressure exchangers are based on the technology used in the Danfoss APP pumps, and the high-pressure booster pumps are based on the vane pump principle enabling a very light and compact design.

The design of the iSave ensures lubrication of the moving parts by the fluid itself.

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Service Guide | APP pump and iSave ERD in SWRO plant

2.Seawater desalination system - terms of understanding

				RO membrane	Permeate
	HP feed		6 HP membrane feed
					8
	HP feed			HP membrane brine flow
	4
				7
			ERD loop flow
	1				iSave
APP high-pressure pump		5	HP feed
	feed		iSave	LP-out brine flow
			2
		LP-in feed		3
				Flow control
				valve
Clean fresh				Brine/Concentrate
				9
seawater
		Feed pump

Low Pressure seawater feed flow to high-pressure pumpLow Pressure seawater feed flow to iSave ERD (LP-in)

Low Pressure brine flow from iSave ERD (LP-out)High Pressure flow from pump to membrane

High Pressure flow from iSave ERD to membrane (HP-out)High Pressure total flow to membrane (+ )

High Pressure brine flow from membrane (HP-in)Permeate flow from membrane

Brine/concentrate flow

	Items	Description
	High Pressure flow from iSave ERD to membrane (HP-out)
	High Pressure total flow to membrane (+ )	ERD loop flow (membrane cross flow)
	High Pressure brine flow from membrane (HP-in)
	High Pressure total flow to membrane	Membrane recovery rate - the % recovery is defined as the
		ratio of permeate flow rate (8) divided by the membrane
	Permeate flow from membrane
		feed flow rate (6).
		Example: (100 m3/250 m3) x 100 = 40%

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Service Guide | APP pump and iSave ERD in SWRO plant

3.What does the APP high-pressure pump do

Flow from the high-pressure pump makes the permeate production.

				RO membrane	Permeate
	HP feed		6 HP membrane feed
					8
	HP feed			HP membrane brine flow
	4
				7
	1				iSave
APP high-pressure pump		5	HP feed
	feed		iSave	LP-out brine flow
			2
		LP-in feed		3
				Flow control
				valve
Clean fresh				Brine/Concentrate
				9
seawater
		Feed pump			Lorem ipsum

Action	Result
Increase HP pump speed	Raise system pressure (6) and permeate flow (8)
Decrease HP pump speed	Lower system pressure (6) and permeate flow (8)
Changing the HP pump speed	Does not change the ERD loop flow (5 and 7)

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Service Guide | APP pump and iSave ERD in SWRO plant

4.What does the iSave The iSave controls the ERD loop flow (5, 6 and 7).

ERD do	The iSave exchanges brine flow with new seawa-
	ter, transfers the brine pressure into booster

pump and sends new seawater into membrane feed.

				RO membrane	Permeate
	HP feed		6 HP membrane feed
					8
	HP feed			HP membrane brine flow
	4
				7
			ERD loop flow
	1				iSave
APP high-pressure pump		5	HP feed
	feed		iSave	LP-out brine flow
			2
		LP-in feed		3
				Flow control
				valve
Clean fresh				Brine/Concentrate
				9
seawater
		Feed pump

Action		Result
Increase iSave speed		Higher membrane loop flow (5 and 7) - lowers membrane recovery rate
Decrease iSave speed		Lower membrane loop flow (5 and 7) - raises membrane recovery rate
Changing the iSave speed		Does not effect the LP feed flow (2 and 3) and the permeate flow (8)
Section view of iSave
			HP-in
High-pressure		Pressure exchanger
booster pump
HP-out
		LP-in	LP-out

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