Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
2002-07-08
2004-09-07
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S168000, C422S169000, C422S170000, C422S224000
Reexamination Certificate
active
06787114
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a wet type exhaust gas desulfurization apparatus and method.
BACKGROUND ART
Conventionally, in spaces for production and residence such as a plant and a building, an incinerator like a boiler is used. Such an incinerator burns fuel. In this time, if being contained in the fuel, the sulfur component is exhausted as sulphur dioxide (SO
2
) gas without being fixed in ash. The sulphur dioxide gas is showered on the ground as acid rain and affects a human body, an animal, and natural environment. Generally, the incinerator is provided with an exhaust gas desulfurization apparatus not to affect adverse influence.
Most of the exhaust gas desulfurization apparatuses installed in the large-sized combustion facilities are a wet type. In the wet type exhaust gas desulfurization apparatus, the exhaust gas is made to contact alkaline absorption liquid like limewater and the sulphur dioxide gas is changed into sulfite. In this way, the sulfite is absorbed in the absorption liquid and is removed. Moreover, the sulfite is oxidized with air and is changed into sulfate. For the oxidation reaction, generally, the technique is adopted in which air is spouted into the absorption liquid.
In the technique in which the air is spouted into the absorption liquid, it is demanded to make the oxidation reaction effective. Therefore, various kinds of techniques are conventionally developed.
FIG. 1
shows a first conventional example of the wet type exhaust gas desulfurization apparatus. The first conventional example of the wet type exhaust gas desulfurization apparatus
101
is provided with an absorption tower
102
which carries out a wet type desulfurization, and a liquid reservoir
103
is arranged below the absorption tower
102
to reserve alkaline absorption liquid b. Alkali absorbent a such as lime is introduced into the absorption liquid b. The absorption liquid b is pumped up into the absorption tower
102
through a pipe
105
by a circulation pump
104
and is sprayed by spray pipes
106
. Combustion exhaust gas d is introduced from the top of the absorption tower
102
, contacts the sprayed alkali absorption liquid b. Thus, sulphur dioxide gas in the exhaust gas reacts with the alkaline absorbent and is changed into sulfite. The sulfite is absorbed by the absorption liquid and falls into the liquid reservoir
103
and is collected therein. Air d is spouted into the absorption liquid a containing the sulfite by a blower
107
. The blower
107
is connected with a plurality of nozzle headers
108
which are arranged in the bottom of the liquid reservoir
103
. The air is spouted into the absorption liquid b from a discharge port
110
provided at the tip of an air supply nozzle
109
extending from each nozzle header
108
. The sulfite in the absorption liquid b reacts with the spouted air and is changes to sulfate. The sulfate stoichiometrically equivalent to the sulphur dioxide absorbed in the absorption liquid b is discharged as waste fluid c. Absorption efficiency in the oxidation technique by the above air blowing method is mainly influenced based on the contact area between air and the absorption liquid.
FIG. 2
shows a second conventional example of the wet type exhaust gas desulfurization apparatus
111
. In the second conventional example, the wet type exhaust gas desulfurization apparatus
111
is composed of stirrer
112
. The stirrer
112
has stirring wings
113
, and the stirring wings
113
are rotated in the absorption liquid of the liquid reservoir
103
. The air is supplied by a blower
107
and spouted into the absorption liquid b from a discharge port
114
arranged in the front of the stirring wings
113
. The spouted air accompanies a spouted stream generated by the stirring wing
113
and is distributed into the absorption liquid b. This technique can promote the oxidation reaction by the distribution of air.
Japanese Laid Open Utility Model Application (JP-A-Heisei 4-137731) shows a third conventional example of the wet type exhaust gas desulfurization apparatus
121
shown in
FIG. 3. A
plurality of jet nozzles
117
are provided to generate jet streams
116
in a predetermined angle into the radial directions of the liquid reservoir
115
. The plurality of jet streams
116
are provided at a predetermined height, and the jet stream from the jet nozzle
117
turns to the circumferential direction of the liquid reservoir
115
. An absorption liquid pipe
119
is arranged in the bottom of the jet nozzle
117
to pass through the liquid reservoir
115
, and a jet stream pump
118
is provided on the way of the pipe
119
. The opening of an air supply pipe
120
is provided on the way of the absorption liquid pipe
119
. Air f is sucked from the air supply pipe
120
by the absorption liquid flowing though the absorption liquid pipe
119
and is spouted into the liquid reservoir
115
from the jet nozzles
117
together with the absorption liquid b. This technique can promote the mixing of the absorption liquid and the air more.
FIG. 4A
shows a fourth conventional example of the wet type exhaust gas desulfurization apparatus
131
. A discharge pipe
122
penetrates the circumferential wall of the liquid reservoir
123
. Absorption liquid is sucked from a liquid reservoir
123
by a liquid pump
124
and circulated through a circulation liquid pipe
125
and a discharge pipe
122
. As shown in
FIG. 4B
, the end of the air blow pipe
126
is inserted into the circulation liquid pipe
125
on the way of circulation liquid pipe
125
. The direction
127
of an air output portion
126
a
of the air blow pipe
126
is almost coincident with the flowing direction of the absorption liquid in the circulation liquid pipe
125
. The air is pressurized by a blower
128
and is outputted from the end of the air blow pipe
126
into the direction
127
. In this way, the air is mixed with the absorption liquid b in the circulation liquid pipe
125
and is spouted from a discharge pipe
122
in the absorption liquid in the liquid reservoir
123
.
The first to fourth conventional examples are superior in the oxidation promotion but the following problems are remained.
In the first conventional example, a checking work of the liquid reservoir
103
is troublesome, because a lot of air supply nozzles
109
are arranged on the whole bottom surface of the liquid reservoir
103
.
In the second conventional example, the rising stream is generated due to air lift operation which accompanies the spouting of the air from the discharge port
114
. The rising stream promotes a narrow region circulation in which the stirring wing
113
absorbs and stirs a part of the liquid again. As a result, the outreach of the stirred liquid stream becomes short and the stirring efficiency decreases.
In the third and fourth conventional examples, air is supplied from the way of the jet nozzle
117
which is connected with absorption liquid pipe
119
or the discharge pipe
122
which is connected with circulation liquid pipe
125
. Therefore, while air bubbles flow through the absorption liquid pipe
119
or circulation liquid pipe
125
together with the liquid, the air bubbles combine and enlarge. As a result, the jet stream is separated into an air phase and an absorption liquid phase. Even if the mixture stream of the air and the liquid is spouted from the jet nozzle
117
or discharge pipe
122
in such a condition, the air bubbles are not uniformly distributed and the perfect oxidation is difficult. Also, the inside of the pipe becomes easy for cavitation erosion.
Therefore, the more increase of the contact area between the liquid and air and the large improvement of the stirring and dispersing capability of the absorption liquid are demanded. Also, it is demanded that the increase and the improvement are achieved in a wide region and uniformly. Furthermore, the large reduction in the number of air supply nozzles and the simplification of the checking work are demanded.
DISCLOSURE OF INVENTION
Therefore, an object of the present invention is to provide a wet
Onizuka Masakazu
Takashina Toru
Mitsubishi Heavy Industries Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Hien
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