GUIDELINES TO OBTAINING THE BEST CONDENSER PROTECTION
Condensers are tubular heat exchangers where the cooling water circulates in a large number of parallel, small-bore tubes. The efficiency of the condenser is strictly proportional to the heat-transfer coefficient of the tube walls, i.e. to how clean the inner surface of the tubes may be.
Condensers tend to foul up over time and the efficiency of the plant decreases (up to 3% loss of generated power is not unusual).
There are two types of fouling:
Some debris which are too large to pass through the tubes, stop on the inlet side of the tube sheet. There are many possible causes to the presence of such debris:
Debris by-pass the inlet screens (carry-over on thru-flow screens, etc.).
There is growth past the screen in the CW pump sumps or in the pipes (shells, seaweed, fish, etc.).
Pieces of packing or growth in the cooling tower for closed-circuit plants.
Various forms of garbage dropped inadvertently (plastic wrapping, twigs, civil structure decay, pebbles, etc.). These debris are arrested by the tube sheet and either:
Plug the pipe inlet totally. The pipe is no longer operational and fills with growth and settled solid matter.
There is a reduction in condenser efficiency. The tube can corrode.
Or they can partially block the tube inlets, thereby creating turbulence in the tube entrance.
This is especially detrimental as the local velocities in turbulence are higher than the acceptable velocity to prevent tube abrasion.
This rapidly leads to tube decay and leaks.
BEAUDREY built the first ever debris filter in 1936. This is the only and perfect remedy to macrofouling. The BEAUDREY debris filter is installed on the inlet pipe, as close as possible to the condenser. It is regularly backwashed.
In most cases, the payback time of such as system is less than two years. (Learn more).
Water contains various dissolved chemicals. It also carries suspended solids such as sludge, micro-sand, limestone powder and biological elements such as bacteria, plankton, seeds, microalgae, etc.
Some dissolved chemical precipitate as the water warms and build up into adherent scale on the tube surface.
Fine mineral particles settle on the low-velocity boundary layers (sludge).
Biological elements adhere to the tube surface and grow, often feeding on the layer of settled particles (ref. photo above).
The resulting troubles are:
Underlying corrosion of the tubes.
Large reduction of the heat transfer by the tube with the consequent loss of generated power (3% and more).
BEAUDREY continuous tube-cleaning systems completely eliminate these problems. They keep the inner part of the tubes clean, they do not remove solid scale build-up.
AVAILABLE TYPES OF TUBE-CLEANING SYSTEMS
Two types are available:
The conventional grid type, used everywhere for the past sixty years, where the cleaning balls are arrested on angled grids. The balls roll along the grid down to the collection box where they are pumped out and sent back upstream of the condenser via a ball-management skid.
When the grids are dirty, the balls are collected and the grids tilted to be backwashed. Unfortunately, many balls remain impinged on the grid and are lost when the grids are tilted. Furthermore, after some time and due to wear, the grids no longer close tightly and some balls pass through the resulting gaps. Balls escaping into the environment are being forbidden world-over. (Learn more)
With the BEAUDREY-patented “ZERO BALL LOSS (ZBL)” system, balls are arrested by a specially-adapted debris filter and pumped out via a ball-handling skid to be re-injected upstream of the condenser.
No balls can escape the system and pollute nature.
BEAUDREY Zero Ball Loss systems are more compact and less expensive than the grid type. (Learn more)
Two Possible Cases:
(1) NEW PLANTS
This is the easiest solution where standard machines can be used.
Following a few basic rules guarantees the efficiency of the tube-cleaning system.
Velocity in the cooling water pipes must be less than 2.5 m/sec (8.2 ft/sec)
Avoid layouts with elbows, double elbows and other such features which generate turbulence, ahead of the tube-cleaning spool pieces.
If it is not possible to avoid such layouts, make provision for installing flow-tranquilizers ahead of the equipment
The CW pipes and water-boxes should include the necessary manholes and door access to the equipment.
BEAUDREY can help you optimize the layout.
(2) EXISTING PLANTS
This is generally more difficult.
Call BEAUDREY to help you work out a safe solution.
While the rules are the same as for new plants, some customizing of the standard equipment is often necessary.
BEAUDREY can design any special layout for you.
The loss of generated power without tube-cleaning is generally more than 1.5% of the total production.
Pay-back time on the investment of using a BEAUDREY tube-cleaning system is short.