PURPOSE: To prevent scaling in the title apparatus by circulating part of a gypsum free filtrate leaving a gypsum separating process to a cooling and dust removing process and maintaining the concn. of Cl- in the cooling and dust removing process to below a specific value.
CONSTITUTION: Exhaust gas 1 is fed to dust removing and cooling tower 2 to remove dust such as carbon and supplied to absorption tower 3 as stad. wet gas of 55W60°C. Lime slurry 4 is introduced into tower 3 to be reacted with SOx in the gas, forming CaSO3. This CaSO3-contg. absorbing liquid is fed to oxidation tower 5 to convert the CaSO3 into gypsum. The gypsum-contg. oxidized liquid is then fed to gypsum separator 6 to separate product gypsum 7. The filtrate is returned to lime preparation vessel 7, and at the same time part of the filtrate is circulated to tower 2. A chlorine-contg. inorg. salt such as NaCl is added to the filtrate circulated to tower 2, and above 1000, esp. 5000W8000 ppm of Cl- is introduced into the absorbing liquid fed to tower 2. Thus, scaling can be prevented esp. in the piping of tower 2.
TSUGAWA HIROTSUGU
MATSUO KATSUHIKO
KOJIMA SUNAO
FUKADA YOSHINOBU
| JPS50136283A | 1975-10-29 | |||
| JPS493874A | 1974-01-14 | |||
| JPS5015784A | 1975-02-19 | |||
| JPS5033994A | 1975-04-02 |