| 摘要 |
PURPOSE:To eliminate the CuS scale with a simple operation and in a highly efficient and economical way, by dipping the part of a machine where the CuS scale is sticking into an aqueous solution containing alkali hydroxide and hydrazine in a prescribed ratio or larger respectively and having a temperature higher than the normal level. CONSTITUTION:The oil cntent on the surface of the CuS scale is removed by a proper process. Then an aqueous solution containing >=1% alkali hydroxide and hydrazine and having a temperature higher than the normal level is enclosed to the part of a machine where the CuS scale is sticking, e.g., at the oil pass side of a heat exchange tube of an oil heater. The CuS scale is left as it is under such conditions for a certain period of time. After this, the layer-shape scale containing mainly CuS is dissolved and separated away. In other words, a part of the CuS is reduced to be turned into Cu2S which is easily dissolved in dilute alkali hydroxide since the hydrazine, i.e., an intensive reducing agent is used in a basic region having a high chemical degree of activity. At the same time, the hydrazine itself is decomposed by the catalytic action of the CuS to generate the N2 gas. With this N2 gas, the layer-shape scale of CuS is exfoliated and destroyed. |
