| 摘要 |
PURPOSE:To make it possible to clean the heat transfer surface of the heat exchanger effectively by using a simple device by a method wherein when the heat exchanger for cooling a cleaning liquid used for purifying a high temperature gas is cleaned, a washing liquid having a higher pH than in the ordinary operation of the heat exchanger is brought into contact with the heat transfer surface on the cooled side of the heat exchanger for a predetermined period of time. CONSTITUTION:Scales generated on the heat transfer surface of the cooled side of a cooler 9 due to the existence of solid components in the washing liquid is measured with a differential pressure meter 13 and a flow rate meter 14 and when the differential pressure or the flow rate of the washing liquid becomes higher or lower than a predetermined value, the heat transfer surface is cleaned. That is, the supply of a pyrolytic material is stopped for a time or the amount of supply of the material is reduced and an inert gas and an alkalline solution are injected into the washing liquid to increase the alkalinity of the washing liquid by opening valves 15 and 16 attached to a gas supply pipe 5 and an alkalline solution supply pipe 6. As a result, the scale becomes softened to be exfoliated easily by alkali. Further, the heat transfer surface is disturbed by air bubbles generating due to the injection of the inert gas so that the scales are exfoliated to thereby further increase the cleaning effect. |
