**4. Nomenclature**


**21** 

*KLAREN BV The Netherlands* 

**on Process Design** 

Dick G. Klaren and Eric F. Boer de

**Self-Cleaning Fluidised Bed Heat Exchangers for Severely Fouling Liquids and Their Impact** 

The invention of the self-cleaning fluidised bed heat exchangers dates back to 1971 when the principal author of this chapter was involved in the discovery and development of a very unique Multi-Stage Flash (MSF) evaporator for the desalination of seawater. The condensers used in this thermal desalination plant used stationary fluidised beds in multi-parallel condenser tubes. The particles fluidised in these tubes consisted of glass beads of 2 mm diameter. These small glass beads knocked of scale crystals from the tube wall at their very early stage of formation and, moreover, the turbulence created by the stirring action of the glass beads in the liquid caused thinning of the laminar boundary layer. This dramatically improved the heat transfer film coefficient in spite of very low liquid velocities in the tubes

Since the early 80s, the chemical processing industries showed a lot of interest for this unique heat exchanger, which seemed to be able to solve any fouling problem, even those problems, which required cleaning of conventional heat exchanger every few days or even

In the next paragraphs we will pay attention to the consequences of heat exchanger fouling and in particular its cost. We explain the self-cleaning fluidised bed technology and also present a couple of installations. We also show some examples where the benefits of the selfcleaning fluidised bed heat exchange technology are responsible for a much wider range of

It can be stated that a general solution to heat exchanger fouling still does not exist. This is not surprising, as knowledge of underlying mechanisms of the fouling process remains limited. Moreover, fouling in heat exchangers often concerns different types of heat exchangers, each with its own unique characteristics. Also, there are large differences in physical properties of the fluids to be applied in the exchangers. The consequences of heat

advantages with respect to process design than non-fouling heat exchange only.

**1. Introduction** 

hours.

and reduced pumping power requirements.

**2. Fouling of heat exchangers** 

exchanger fouling are:

**2.1 Consequences of heat exchanger fouling** 

#### **5. References**

