Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1998-11-10
2003-01-14
Johnson, Jerry D. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S168000, C422S169000, C422S224000, C095S195000, C095S196000, C095S197000, C095S199000, C095S200000, C095S202000, C095S057000, C096S054000, C096S028000, C096S015000, C096S134000
Reexamination Certificate
active
06506348
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a heavy oil fired boiler exhaust gas treatment apparatus.
Conventionally, as shown in
FIG. 4
, as a treatment method for SO
3
in exhaust gas of a heavy oil fired boiler
401
, there has generally been used a method in which a salt such as ammonium sulfate ((NH
4
)
2
SO
4
) is yielded by pouring a neutralizer such as ammonia on the upstream side of an electric dust collector
402
, and the SO
3
is trapped together with soot and dust by the electric dust collector
402
. The exhaust gas passes through a wet type exhaust gas desulfurizer
403
and is discharged from a stack
405
. When far higher dust removing performance is required, a wet type electric dust collector
404
is installed on the downstream side of the wet type exhaust gas desulfurizer
403
to effect high-level dust removal.
However, a neutralizing salt yielded by the pouring of a neutralizer consists of fine particles, so that it is difficult to trap the neutralizing salt by the electric dust collector
402
and an absorption tower of the desulfurizer
403
. Further, since ammonium sulfate is trapped as part of soot and dust together with soot and dust in the electric dust collector
402
, the capacity of the electric dust collector
402
must be increased. Therefore, the conventional method poses a problem in that not only the site area but also the installation cost and operation cost increase.
Thereupon, a heavy oil fired boiler exhaust gas treatment apparatus which solves above problems has been desired.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above situation, and accordingly an object thereof is to provide a heavy oil fired boiler exhaust gas treatment apparatus which removes soot and dust and SO
3
in the heavy oil fired boiler exhaust gas efficiently at a low cost without using an excessively large apparatus.
To solve the above problems, the present invention provides a heavy oil fired boiler exhaust gas treatment apparatus comprising a charging device provided at the inlet of an absorption tower of a wet type exhaust gas desulfurizer and neutralizer pouring means provided on the upstream side of the charging device for pouring a neutralizer into exhaust gas and for neutralizing SO
3
in the exhaust gas.
Also, the present invention provides a heavy oil fired boiler exhaust gas treatment apparatus comprising an electric dust collector for collecting dust in exhaust gas sent from a heavy oil fired boiler, neutralizer pouring means provided on the upstream side of the electric dust collector for pouring a neutralizer into the exhaust gas and for neutralizing SO
3
, and a wet type exhaust gas desulfurizer, wherein a charging device is provided at the inlet of an absorption tower of said wet type exhaust gas desulfurizer.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, an accelerating dust collector may be provided at the outlet of the absorption tower.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided a spray for spraying water into the exhaust gas on the upstream side of an accelerating dust collector.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided separator for separating unburned carbon from an absorbent liquid obtained from the absorption tower.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided means for separating and recovering a neutralizer in an absorbent liquid drawn from an oxidation tank of the wet type exhaust gas desulfurizer.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, a high-pressure spray may be provided immediately behind the charging device.
As is apparent from the above description, according to the present invention, there is provided a heavy oil fired boiler exhaust gas treatment apparatus which removes soot and dust and SO
3
in the heavy oil fired boiler exhaust gas efficiently at a low cost without using an excessively large apparatus.
That is, according to the present invention, by installing a charging device, soot and dust (containing a neutralizing salt such as ammonium sulfate) are charged. Further, by installing a high-pressure (pressurized) spray, tiny water drops can be sprayed, by which fine particles can be agglomerated and enlarged. Thereby, soot and dust can be trapped in the absorption towers with high efficiency.
When an accelerating dust collector is installed, soot and dust can be recovered efficiently, so that an electric dust collector, which requires a high cost, can be omitted or made compact.
Further, when a liquid cyclone and means for separating and recovering a neutralizer are installed, unburned carbon and neutralizer trapped in the absorption towers can be recovered, so that the usage can be reduced. Therefore, the heavy oil fired boiler exhaust gas treatment apparatus can be improved as a whole.
REFERENCES:
patent: 3782888 (1974-01-01), Cnare
patent: 3960687 (1976-06-01), Bakke et al.
patent: 4297332 (1981-10-01), Tatani et al.
patent: 4305909 (1981-12-01), Willett et al.
patent: 4919696 (1990-04-01), Higashi et al.
patent: 5015443 (1991-05-01), Ito et al.
patent: 5525317 (1996-06-01), Bhat et al.
patent: 5958335 (1999-09-01), Okazoe et al.
patent: 6007783 (1999-12-01), Ochi et al.
patent: 08243340 (1996-09-01), None
European Search Report for EP 98 12 1004 completed Jul. 5, 1999.
Ochi Eiji
Onizuka Masakazu
Shinoda Takeo
Takashina Toru
Alston & Bird LLP
Doroshenk Alexa A.
Johnson Jerry D.
Mitsubishi Heavy Industries Ltd.
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