Revamp of existing conventional heat exchangers

The self-cleaning heat exchange technology as developed by KLAREN can easily be retrofitted into existing vertical conventional exchangers which suffer from serious fouling. These possibilities are particularly interesting for the type of reboilers, evaporators and crystallizers as shown in Figure 1.

Generally speaking the requirements specified by plant management for the majority of revamps can be summarized as follows:

• The same process conditions should be maintained as in the original installation, i.e. flow, evaporation in the tubes or suppressed evaporation in the tubes with flash evaporation in the column.
• The connections to the column should be maintained.
• The installed pumps should be used.
• The revamp must be carried out within the available space.

The revamped reboiler shown in Figure 2 meets the above requirements differing from the original installation only by an extension of the existing inlet channel, a minor modification of the existing outlet channel, a separator with external downcomer and some connecting piping.

At this very moment, already one existing heat exchanger in a paper mill in the Netherlands has been revamped into a selfcleaning configuration. Another revamp is planned for a chemical plant in the United States. A survey has indicated that in al potential for the revamp of approximately 1,500 heat exchangers in evaporators, reboilers and crystallizers into a self-cleaning configuration.

Figure 1: Existing vertical conventional reboiler	Figure 2: Existing vertical conventional reboiler revamped into self-cleaning configuration

Revamping opens a huge market for the KLAREN self-cleaning heat exchange technology.

The improvements of the KLAREN self-cleaning heat exchange technology of the past two years make a revamp of existing fouling heat exchangers into a self-cleaning configuration much easier. It is generally believed that world-wide there are many thousands severely fouling existing vertical heat exchangers, installed in forced circulation evaporators, reboilers and crystallizers, which would justify a revamp into a self-cleaning configuration. This number, which is still growing, does not include the self-cleaning heat exchangers for new evaporators, reboilers and crystallizers.

At this moment, KLAREN BV is in contact with the following companies which have shown interest in a revamp of their existing installations:

• A major Norwegian producer of white minerals is interested to revamp two severely fouling heat exchangers, each 2,200 m² heat transfer surface, into a self-cleaning configuration. Both exchangers are installed in forced circulation evaporators and have been equipped with tubes with a diameter of 22 x 1.0 mm. Only the new ideas of KLAREN BV, regarding the application of the self-cleaning technology in small diameter tubes, make this revamp possible.
  
  
• A German producer and market leader of white pigments (TiO2) has shown interest to revamp two heat exchangers equipped with graphite tubes into a self-cleaning configuration.
  
  
• A Mexican company has shown interest for the revamp of six heat exchangers in crystallizers which suffer from severe fouling due to precipitations of Glauber's salt. After a revamp, the production of the crystallizers is expected to increase by at least 10%.
  
  
• A US producer of phosphoric acid has shown interest to revamp 10 (!!) heat exchangers in evaporators into a self-cleaning configuration. Most heat exchangers contain graphite tubes. The revamp of these exchangers makes it possible to increase the production of the existing evaporators, which, otherwise, could only be realized by installing a complete new multi-effect evaporator.
  
  
• A pulp mill in the US is interested to revamp two heat exchangers in a multi-effect black liquor evaporator, which would increase the evaporation capacity of this evaporator by approx. 30%.
  
  
• A chemical plant in Indonesia experiences serious fouling of the heat exchangers in some of their reboilers. At this very moment, plant management is evaluating the various possibilities on how to proceed with the revamp of the existing conventional heat exchangers into a self-cleaning configuration employing the KLAREN technology.

Other revamps are considered for an evaporator in India and for two reboilers (so-called 'copper boil') in nickel refining plants in Canada and Australia. In Australia, there is also much interest to look into the possibilities of revamping evaporators in the nlumina industry for the concentration of bauxite liquor.