The zero-fouling heat exchanger technology presents an on-line continuous cleaning method that uses solid particles. These solid particles, made of glass, ceramic or metal (cut metal wire) with diameters of 1.5 to 5 mm, create a mild scraping or polishing effect on the wall of the heat exchange tubes. Their scouring action removes the fouling deposits from the tube wall at an early stage of formation and keeps the heat transfer surface clean. Besides this, the particles enhance the heat transfer at low liquid velocities and reduce pressure drop compared to conventional heat exchangers.
Any shell and tube heat exchanger can be designed for zero-fouling of the respective heat transfer surface as long as the rate of fouling removal by the scouring action of the particles exceeds the rate of fouling precipitation.
The operating principle of the zero-fouling fluidized bed heat exchangers is based on the circulation of solid particles through the tubes of a vertical shell and tube heat exchanger. The fouling liquid is fed upward through the vertical shell and tube heat exchanger that incorporates specially designed inlet and outlet channels. The solid particles are also fed at the inlet, where a flow distribution system uniformly provides the liquid and suspended particles throughout the internal surface of the bundle. The particles are transported by the upward flow of liquid through the tubes, where they create the mild scraping or polishing effect on the wall of the heat exchange tubes, thereby removing any deposit at an early stage of fouling formation. Inside a separator the particles disengage from the liquid and are returned to the inlet channel through an external down comer, and the cycle is repeated. The process liquid fed to the exchanger is divided into a main flow and a control flow that transport the particles into the heat exchanger.
By varying the control flow, it is possible to control the amount of particles in the tubes. This controls the efficiency of the cleaning mechanism, allowing the particle circulation to be either continuous or intermittent.
Watch the video presentation about the working principle of the zero-fouling heat exchanger.
Watch the video presentation about the working principle of the self-cleaning heat exchanger.