Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Reexamination Certificate
1998-02-20
2001-02-20
Tran, Hien (Department: 1764)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
C422S168000, C422S169000, C422S171000, C095S064000, C095S070000, C096S032000, C096S052000, C096S053000
Reexamination Certificate
active
06190630
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART STATEMENT
This invention relates to a flue gas treating process for removing sulfur oxides and dust from exhaust gas discharged from a boiler or the like, and an apparatus therefor.
An example of a conventionally and commonly used process for removing sulfur oxides and dust from exhaust gas discharged from a boiler or the like is illustrated in FIG.
5
. In
FIG. 5
, exhaust gas A discharged from a boiler or the like and containing sulfur oxides and dust is first introduced into a dry electrostatic precipitator
101
, where dust is removed therefrom. Then, the exhaust gas A is generally treated in a wet desulfurization step using an absorption tower
102
in which the exhaust gas A is cleaned by bringing it into contact with an absorbing fluid B containing an alkaline agent C (e.g., limestone) that is held in a circulation tank
103
, raised by means of a pump
104
, and sprayed from a spray nozzle
105
. Usually, most of the dust which was not collected in dry electrostatic precipitator
101
, together with sulfur oxides, is removed in the wet desulfurization step, so that high overall dust-removing performance is achieved.
In recent years, with increasing attention to the problem of environmental protection, the concentration of dischargeable dust in exhaust gas tends to decrease. However, dry electrostatic precipitators are expensive equipment and, moreover, require a wide floor space. Consequently, it is desired to reduce the capacity of this equipment. However, since a reduction in the capacity of an electrostatic precipitator causes a loss in dust-removing performance, it is necessary to develop inexpensive and simple dust-removing equipment which can make up for such a loss in performance.
In view of the above-described circumstances of the prior art, it is an object of the present invention to provide a flue gas treating process which can achieve desulfurization and dust removal by use of simplified equipment and makes it possible to reduce the capacity of an electrostatic precipitator installed on the upstream side, as well as an apparatus therefor.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a flue gas treating process for removing sulfur oxides and dust from exhaust gas containing sulfur oxides and dust by using an absorption tower into which an absorbing fluid containing an alkaline agent is sprayed, comprising the steps of equipping the absorption tower with integrally formed dust collection means having dust collecting plates and discharge electrodes, and with dust separation means for sweeping off the dust collected by the dust collection means; and treating the exhaust gas in the dust collection means and subsequently cleaning the exhaust gas in the absorption tower, whereby desulfurization and dust removal are effected while the collected dust is being swept off by said dust separation means.
According to the present invention, there is also provided a flue gas treating apparatus comprising an absorption tower for desulfurizing exhaust gas containing sulfur oxides and dust by bringing it into contact with an absorbing fluid containing an alkaline agent, a circulation tank disposed at the bottom of the absorption tower for holding the absorbing fluid, and spray means for spraying the absorbing fluid within the circulation tank into the absorption tower, characterized in that dust collection means having dust collecting plates and discharge electrodes is installed in the upper part of the absorption tower, and the dust collection means is equipped with dust separation means for sweeping off the dust collected by the dust collection means.
In one specific embodiment, the flue gas treating apparatus of the present invention comprises an absorption tower for desulfurizing exhaust gas containing sulfur oxides and dust by bringing it into contact with an absorbing fluid containing an alkaline agent, a circulation tank disposed at the bottom of the absorption tower for holding the absorbing fluid, and a circulating pump for raising the absorbing fluid from the circulation tank and spraying it into the absorption tower, and is characterized in that a simplified electrostatic precipitator having dust collecting plates and discharge electrodes is installed in the upper part of the absorption tower, and the simplified electrostatic precipitator is equipped with a high-voltage power supply for energizing the simplified electrostatic precipitator, and a hammering device for sweeping off the dust collected by the simplified electrostatic precipitator.
In the practice of the present invention, an absorption tower equipped with dust collection means at the inlet thereof is used as the absorption tower for effecting wet desulfurization, and dust is enlarged and washed out in the absorption tower to improve dust-removing performance in the absorption tower. This makes it possible to decrease the load imposed on a dry electrostatic precipitator or like device installed upstream of the dust collection means and, as a result, reduce the size of the dry electrostatic precipitator or like device.
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Katayama Hiroyuki
Okazoe Kiyoshi
Onizuka Masakazu
Takashina Toru
Foley & Lardner
Mitsubishi Heavy Industries Ltd.
Tran Hien
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