Removal of gas-side particulate fouling layers by foreign particles as a function of flow direction

Removal of particulate fouling layers by externally injected particles as a function of flow direction with respect to gravity is investigated experimentally. Three orientations of flow have been investigated, horizontal flow, upward flow and a downward flow. It is found that fouling starts at the point of stagnation irrespective of the flow direction, and also starts at the top point of the heat exchanger tubes. Particulate fouling grows from these two points except for the downward flow, were the flow stagnation point coincides with the top point of the heat exchanger tubes and the growth of the fouling layer starts only from one point. It was not possible to remove the fouling layer in case of a horizontal and an upward flow by the externally injected particles, however in case of a downward flow most of the fouling layers were removed by the external particles. It can be concluded that the downward flow is the best flow orientation to linger particulate fouling and for removal of fouling layers by externally injected particles.