Operation Settings; Balancing The X-Changer Module; Bm Hp Circulation Pump; Checking The Direction Of Rotation - Grundfos BMEX Series Montage- Und Betriebsanleitung

9.5 Operation settings

The flow and discharge pressure of the BMEX system should
always be kept within the ranges for which it was originally
designed. See the "Technical specification" supplied with the
system.
If the system requires flows and pressures outside the design
range, changes are possible. Please contact Grundfos.

9.6 Balancing the X-Changer module

The following procedure should be applied to
Note
achieve balanced flows.
This section and the subsequent subsections make references to
the piping and instrumentation diagram, fig. 16.
Procedure:
1. Start the sea-water feed pump (P1).
2. Adjust the low-pressure reject-water valve (V3) on the
discharge side of the X-Changer (X1) until the low-pressure
sea-water inlet flow (FM2) equals the calculated sea-water
discharge flow (FM3).
3. Start the BM hp circulation pump (P4). See section
circulation pump.
4. Adjust the variable-frequency drive on the BM hp circulation
pump (P4) or control valve (V2) until the desired flow rate is
achieved as indicated by the high-pressure flowmeter (FM3).
FM3 = FM2 (= balanced flow).
To achieve balanced flow through the X-Changer (X1), use
flowmeters installed on the low-pressure sea-water inlet piping
and high-pressure sea-water discharge piping. All flows in and
out of the X-Changer should be balanced to within 5 % for
optimum operation.
If any doubt exists in reading the flowmeter, the low-
pressure sea-water inlet should be the greater of the
Note
two flows (FM2 > FM3).
Operating the X-Changer with unbalanced flows may
result in contamination of the sea-water feed by the
Note
brine reject and consequently lower efficiency.
The X-Changer module is designed to operate at fluid mixing
levels below 5 %. Balanced flows control the mixing of
concentrate with the feed. Flowing the sea-water inlet much less
than the sea-water discharge will result in lower-quality permeate,
increased feed pressure and higher energy consumption.
Recommended practice for the BM hp circulation pump is to use
a slightly oversized pump to handle projected membrane
concentrate flows, taking into account seasonal variations,
membrane fouling and manifold losses. The flow and pressure of
the BM hp circulation pump can be controlled with a variable-
frequency drive (P4) or control valve (V2).
The low-pressure and high-pressure flows through
the X-Changer must never exceed the rated
Caution
maximum flow. The only reliable way to determine
this flow is to use a low-pressure flowmeter (FM2) or
a high-pressure flowmeter (FM3), respectively.
12

9.7 BM hp circulation pump

This section and the subsequent subsections make references to
the piping and instrumentation diagram, fig. 16.
The BM hp circulation pump must be filled with water
Note
before startup.
Warning
The BM hp circulation pump is not allowed to run
against a closed discharge valve for more than 5
seconds as this will cause an increase in
temperature/formation of steam in the pump which
may cause damage to the pump and motor.
If there is any risk of the BM hp circulation pump
running against a closed discharge valve or no flow,
a minimum liquid flow through the pump should be
ensured by connecting a bypass/a drain to the
discharge side of the pump. The drain can for
instance be connected to a tank.
To start up the BM hp circulation pump, proceed as follows:
1. Ensure an inlet pressure on the pump (min. 1 bar and max. 80
9.7 BM hp
bar).
2. Start the BM hp circulation pump.
In systems involving the risk of water hammer in connection with
start/stop, the necessary measures must be taken to reduce this
risk, e.g. by installing a diaphragm tank.
During operation, the inlet pressure must be checked in
accordance with section
The BM hp circulation pump is now ready for operation.

9.7.1 Checking the direction of rotation

Procedure:
1. Close the control valve (V2) on the discharge side of the BM
hp circulation pump (P4) to approx. 1/3 of maximum flow.
2. Start the BM hp circulation pump, and record discharge
pressure and flow readings.
3. Stop the pump, and interchange two of the phases to the
motor.
4. Restart the pump, and re-record discharge pressure and flow
readings.
5. Stop the pump.
6. Compare the results recorded under points 2 and 4. The
connection which gave the larger pressure and flow is the
correct direction of rotation.
The check for the direction of rotation should last for the shortest
possible time.
9.5 Operation settings.