| 摘要 |
PURPOSE:To cause solution to be supplied to a concentration devicd to carry out both scale solving and recovering operations to impart a self-cleaning function to the device by suitably carrying out changeover of a solution supply path and a processing path in each of a number of evaporating cans. CONSTITUTION:When a first evaporating can 1 and a second evaporating can 3 are used as a front stage and a rear stage, respectively, scales do not adhere to the calandria pipe wall of a first heating can 2, whereas the pipe wall of a second heating can 4 comes into contact with the concentrated solution and scales adhere therto and grow. At a suitable time period, when a second evaporating can 3 is changed over to the front stage and the first evaporating can 1 to the rear stage, a new crude solution enters the bottom part of the second evaporating can 3, making detour to the lower part of the second evaporating can 4, and solving and recovering scales of the pipe wall while ascending in each of heating pipes. Vapor is directly sent to the second evaporating can 4, and vapor within the second evaporating can 3 heats the first heating can 2. Therefore, the concentrated solution is led out from the first evaporating pipe 1 side. By this changeover operation, the efficiency and thermal efficiency of the device can be improved constantly without adverse effect by scales. |
