Ball Tube Cleaning

When placed perpendicularly to a regular flow of fluid, an obstacle generates, downstream of its position, a series of "Karman" Vortexes. The velocity of the fluid in the first Vortex is very high: over 5 times the on-line velocity.

Technos patented equipment is an application of this phenomenon relative to collection of the sponge balls downstream of the main grids in the strainer section. This device is self cleaning and not sensitive to possible debris from the cooling water.

This point was demonstrated in a test unit where the Vortex Chamber had been filled with stones and gravel. Upon starting water circulation, it emptied in two seconds.

The first patent application for a condenser tube cleaning system was made as early as 1927 by an American engineer, Mr. Schmidt, from Westinghouse, Pennsylvania.

The basic idea was the continuous recirculation of balls in the tubes of the condenser, and the now available products still use the same concept. In the 50's, sponge rubber balls appeared in Europe and were used as a cleaning agent in the same basic equipment: injection nozzles, strainer section, recirculation pump.

In the 70's, the French National Utility developed a large and still unmatched Nuclear Power Plant program. New highly efficient and reliable equipment was needed for this program. At that time, Technos, then a Subsidiary of C.E.M., a European Leader in Power Equipment, started marketing this new equipment dedicated to improving the efficiency of these new large condensers.

Continuous cleaning of internal tube surfaces is accomplished by constant circulation of sponge rubber balls having a diameter slightly larger than the tube diameter.

These sponge rubber balls are injected into the cooling water inlet. The water flow carries them into the inlet water boxes, then through the tubes, and finally into the ball strainer located at the cooling water outlet.

From there, they are extracted and pumped through the ball collector and back to the cooling water inlet. The ball collector allows collection of the sponge rubber balls prior to backwashing the strainer grids.

All the 1,300 MW French N.P.P.'s equipped with C.T.C.S. have Technos equipment. Technos continues to develop devices which provide superior operation and automation of cleaning systems: control equipment, new sponge rubber balls, etc...

The continuous cleaning of condensers and heat exchangers permanently maintains the efficiency of heat transfer of this equipment, without mechanical or chemical cleaning of the tubes and without increasing the number of outages.

Cleaning is necessary every time raw water is used as a cooling medium. This water induces different types of fouling, such as:

- settling of materials in suspension (silts, muds, slime) which affects mostly the bottom part of the inside of the tubes,
- biological fouling due to the presence in water of bacteria and/or marine organisms,
- crystallization of the soluble elements of cooling water (such as calcium carbonate, calcium silicate, sulphate, magnesium salt) which must be removed before scaling,
- formation of sea marine growths (organisms).
Fouling can lead to three major problems:

- corrosion under deposit,
- corrosion created by the destruction of the protective film inside the tube because of the settlement of marine organisms, such as barnacles. The cleaner the sea water is, the more marine organisms settle,
- reduction of the heat transfer capacity of the condenser.

The efficiency of heat transfer in the condensers of steam turbines has direct effect on the power production. Experience has shown that a reduction of 1 mbar in the condenser vacuum of a 900 MW Power Unit leads to a final loss of about 1 MW of power output.

An uncleaned condenser can easily lose over 10 mbars. In such a case the use of a CTCS will increase the power output by more than 10 MW.

Hence it is extremely important to maintain the tubes of the condenser as clean as possible, using highly efficient and reliable equipment, for which the pay back period will be very short.


High efficiency
Balls are immediatly collected and reinjected in the condenser inlet. They do not remain in the collecting area waiting to find the ball outlet. Balls are extracted in the central area of the strainer (highest velocity) and not along the walls (lower velocity). Velocity generated by the Vortex is over 5 times the on-line velocity of water.

Self cleaning collecting device
Power of the Vortex allows self cleaning of the collecting area. The system works even without a Debris Filter upstream. It has proven to be able to evacuate zinc anodes detached from the cathodic protection of a condenser water box, as shown below :

Perfect sealing
A double control (Torque and position) allows a perfect sealing of the grids and guarantees that no cleaning ball are escaping from the circuit.

Corrosion protection
Special painting when using non corrosive fresh water. CuNi plated for desalination plants. Rubber lining in sea or corrosive water. Technos provides a two layer rubber lining. One hard side to ensure good bonding to metal in vacuum condition and one softer side providing shock resistance.

Grids
Very sturdy design and rigid frame constructions of the collecting grids.

Technos Tube Cleaning System Benefits

Continuous cleaning of internal surfaces of condenser tubes provides definite gains. Our heavy duty tube cleaning system will:

- maximize heat transfer across tube walls,
- improve condenser vacuum,
- increase unit operating efficiency,
- lower fuel consumption,
- increase unit MW output,
- extend tube life by removing corrosive deposits,
- eliminate costly downtimes and the high cost of mechanical or chemical cleaning of tubes,
- lessen or eliminate the need for chemical treatment.

Plant performance improves, producing considerable cost savings and quick payback.

High Perfomance and Heavy Duty

The basic requirement for achieving high performance with a continuous on-line condenser tube cleaning system is a good flow pattern troughout the circuit, and particularly through the ball strainer.

The patented Technos ball strainer designs produce and maintain a very effective circulation of sponge rubber balls and offer considerable improvements over other ball strainer designs.

Each tube is cleaned more often so that it is always in perfect operating condition.

Range of applications:

- shell and tube condensers and heat exchangers of all sizes for Power and Process Industries,
- desalination plant heat exchangers,
- systems using ferrous sulphate treatment to smooth out the Fe2+ film coating.

Revamping or new

Technos tube cleaning systems are installed in new or in existing plants. Installation and turnkey contracts can be provided.