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any industrials projects must find CWS, it`s very important items to make cooling for pump and motors also electrical panels.
design of CWS (COOLING WATER SYSTEM) is different from site to another.
the following drawing is sample for kind of these systems
The cooling circuit flow rate will be monitored using an electromagnetic
flowmeter that is fitted with a digital display for instantaneous flowrates.
The equipment within the pumping station requires cooling to operate effectively.
These items known as Consumers are cooled by a constant supply of water.
The objective is to deliver a CWS that transfers the heat energy from the
Consumers to the product water. The amount of heat energy to be dissipated is
summarized below.
CWS Healthy Signal
The main pumps and booster pumps require the supply of cooling water to operate. As
part of their start procedure, confirmation of a healthy cooling water supply is needed.
The Cooling UNCON can confirm the system by monitoring the following:
1. Primary circuit flow meter is monitoring a flow within range
2. Secondary circuit flow meter is monitoring a flow within range
3. Primary circuit inlet temperature is in range
4. Secondary circuit outlet temperature is in range
Primary Cooling Circuit
Product water is pumped from the distribution pipework, filtered and passes
through Duty/Stand-by Heat Exchangers, to absorb heat generated by the
consumers before being fed back into the product water distribution system.
The loop consists of:
• Duty/Stand-by pump set
• Check valves
• Isolation valves
• Pressure gauges
• Air vents
• Vacuum breakers
• Isolation valves
• Motorised control valves
• Drain points
• Backflush filters
• Local and remote pressure indication
• Local and remote temperature indication
• Local and remote Flow indication
• Local and remote Differential Pressure indication (Filters and Heat exchangers)
• Duty/ Stand by Heat Exchangers..
Manual Control
The local control panel will have a 3-position switch with Manual, Off, Auto. The
manual selection will start the pump, ignoring alarm conditions generated by Cooling
UNCON. This is only to be used and supervised by a competent engineer. The pump
will not stop automatically and could lead to system conditions outside of design
parameters.
The position of the switch is monitored by Cooling UNCON. Alerting the operator that
a pump is in ‘manual’ control.
The starter overload and pump thermistors are the only inhibit to remain active in
manual mode
Back Flush Filters
The product water carries dissolved and suspended solids which can cause
blockages in the plate heat exchangers which reduce efficiency. To protect each
heat exchanger and reduce the frequency of cleaning, the primary circuit is fitted
with dedicated backflushing filters which remove these particles from the product
water before entering the heat exchangers.
Water passes into the filter through a coarse mesh to remove large particles.
The water then passes through a second finer mesh before being discharged from the
filter. This fine mesh becomes saturated with fine partials as the filter is being used
causing the pressure within the filter to rise as it becomes saturated. The difference
in the internal and downstream pressure can be measured to indicate when the
filter shall begin cleaning.
Heat Exchanger – Primary Side
Plate heat exchangers are susceptible to blockages due to particulates and scaling,
acting as a barrier to heat transfer and reducing the effectiveness of the unit. There
is a pressure drop across the inlet and outlet of the heat exchanger of ~0.968 bar.
This differential pressure will rise as the scale builds up on the heat transfer
surfaces and debris partials block the flow path.
Consumers will be connected to a closed loop distribution main. The loop consists of:
• Duty/ Stand by pump set
• Check valves
• Isolation valves
• Air vents
• Vacuum breakers
• Motorised control valves
• Drain points
• Local and remote pressure indication
• Local and remote temperature indication
• Local and remote Flow indication
• Local and remote Differential Pressure indication (Heat exchangers)
• Pressure safety relief valve
• Chemical dosing system
• Pressurisation unit – Package plant
• Expansion vessel
• Duty/ Stand by Heat Exchangers
Chemical Treatment
Chemicals are added to the closed-circuit ring main to inhibit corrosion and scaling
of the pipework and equipment. A base level of inhibitor would be added when the
system is initially filled. To maintain the correct amount of inhibitor in the system
additional chemical needs to be added whenever the pressurisation unit runs to top
up the system with untreated water.
Consumer Flow control
Each consumer will have a local flow metering and a throttling installed. The operator can
adjust the valve position to match the flow to calculated flow rate. The throttling valve can
also be used as an isolation valve.