Deodorizing system

The present invention relates to a deodorizing system for reducing the size of a facility and realizing the thermal efficiency much higher than the prior art, wherein a deodorizing furnace 1 is connected with thermal equipment 8 which uses a heated gas current as a heat source through an out-of-furnace circulating path 4 in order to circulate combustion exhaust gas in a deodorizing furnace 2 which has been used for incineration or thermal decomposition of odor components. When the combustion exhaust gas passes through a regenerative bed 5A or 5B on an intake side of the out-of-furnace circulating path, a part of sensible heat of the combustion exhaust gas is recovered in the regenerative bed 5A or 5B and the combustion exhaust gas is turned into a heated gas current that can be used in the thermal equipment 8 to be then supplied to the thermal equipment 8. Subsequently, upon completion of a predetermined process in the thermal equipment 8, the combustion exhaust gas is again made to have a high temperature and returned to the deodorizing furnace 2 by utilizing the recovered heat in the regenerative bed 5B or 5A on an outlet side of the out-of-furnace circulating path.

FIELD OF THE INVENTION 
The present invention relates to a deodorizing system for removing odors 
generated in a thermal equipment which utilizes a gas current having a 
relatively-medium/low temperature in a hot-air drier or a foaming oven as 
a heat source to carry out a predetermined process. 
BACKGROUND OF THE INVENTION 
A deodorizing system such as shown in FIG. 5 has been conventionally 
adopted in a process for removing gas (referred to as odor gas) including 
odor components generated in a foaming oven or a hot-air drier such as a 
paint drying oven. The deodorizing system comprises: a hot blast stove 102 
for supplying hot air having a medium/low temperature; a thermal equipment 
101 such as a hot-air drier or a foaming oven for utilizing hot air 
supplied from the hot blast stove 102 to effect predetermined drying or 
foaming process on a work W; and a deodorizing furnace 103 which takes out 
and burn or heat-decomposes the odor gas generated in the thermal 
equipment 101 for deodorization. Here, hot air having a medium/low 
temperature, e.g., approximately 300.degree. C. required in the thermal 
equipment 101 is generated in the hot blast stove 102, and atmosphere gas 
or flames having a high temperature, e.g., approximately 1000.degree. C. 
required for burning or heat-decomposing the odor gas components is formed 
in the deodorizing furnace 103. 
The odor gas generated in a paint drying oven or a foaming oven, however, 
includes a large quantity of mist before deodorization and this mist is 
high-temperature gas including a large amount of carbonized dust after 
deodorization, whereby heat recovery becomes difficult. Even though a heat 
exchanger is used to carry out heat recovery, the heat exchanger may soon 
be out of service and the heat efficiency is low. Thus, the 
high-temperature gas generated in the deodorizing furnace is not subjected 
to the effective heat utilization and it is directly exhausted. A 
difference in temperature between the heat required in the thermal 
equipment and the heat required for deodorization is not less than 
approximately 700.degree. C., and hence a common heat source can not be 
used. Two different heat sources must be prepared for the hot blast stove 
and the deodorizing furnace, thereby taking a large space and increasing 
the facility cost. 
DISCLOSURE OF THE INVENTION 
It is, therefore, an object of the present invention to provide a 
deodorizing system having a compact equipment and a thermal efficiency 
that is much higher than that in the prior art. 
To achieve this aim, the present invention provides a deodorizing system 
for removing odor components generated from a thermal equipment which 
utilizes a gas current having a medium/low temperature as a heat source, 
comprising: a thermal equipment; a deodorizing furnace provided with a 
burner which mixes gas including the odor components emitted from the 
thermal equipment into a flame and burns it; and an out-of-furnace 
circulating path which includes a circulating passage connected to the 
thermal equipment, a circulating fan and the deodorizing furnace through a 
pair of circulating openings, takes out combustion exhaust gas from the 
deodorizing furnace to the outside of the furnace through one circulating 
opening and passes the combustion exhaust gas through the thermal 
equipment to flow back into the deodorizing furnace through the other 
circulating opening. Further, the out-of-furnace circulating path 
comprises regenerators provided to positions dose to the pair of 
circulating openings of the deodorizing furnace, respectively, and a 
passage switching device for periodically switching a direction of a gas 
current between the circulating fan and the regenerators. Burning the 
burner and changing over the passage switching device periodically switch 
a direction of the gas current to the deodorizing furnace, and the 
combustion exhaust gas taken out from the deodorizing furnace is turned 
into the hot air having a medium/low temperature required for the thermal 
equipment through the regenerators and it is then fed to the thermal 
equipment. Further, the recirculating gas including odor components 
generated in the thermal equipment is again made to have a high 
temperature through the regenerators and flows back into the deodorizing 
furnace for combustion. 
According to this deodorizing system, when the combustion exhaust gas in 
the deodorizing furnace having used for incinerating or thermally 
decomposing the odor components passes through the regenerator on the 
intake side of the out-of-furnace circulating path, the sensible heat of 
the combustion exhaust gas is partially recovered by the regenerator so 
that this gas be turned into the gas current having a medium/low 
temperature utilized in the thermal equipment and then supplied to the 
thermal equipment. Upon completing a predetermined operation in the 
thermal equipment, the gas is made to have a high temperature by using the 
recovered heat in the regenerator on the outlet side of the out-of-furnace 
circulating path and the gas is returned into the deodorizing furnace. 
Therefore, of the heat generated in the deodorizing furnace, the heat 
which can not be satisfactorily recovered by the regenerator and is wasted 
can be used as a heat source for the thermal equipment, thereby reducing 
the size of the facility and the cost without requiring a separate hot 
blast stove for the thermal equipment. In addition, the heat wasted in the 
regenerator for obtaining the hot air having a medium/low temperature is 
again recovered and returned into the deodorizing furnace when supplying 
the odor gas generated in the thermal equipment to the deodorizing 
furnace, and hence the deodorizing system which does not exhaust the heat 
unnecessarily and has a high thermal efficiency can be realized. 
Furthermore, according to the deodorizing system of this invention, since 
the recirculating gas including the odor components which are flown back 
into the deodorizing furnace via the thermal equipment is again made to 
have a high temperature through the regenerators, a temperature of the 
atmosphere gas in the deodorizing furnace can be readily controlled by 
adjusting a quantity of an increase in heat effected by combustion of the 
burner, i.e., adjusting a quantity of fuel injection. Moreover, the 
ignitionability and the stability of flames are improved and the flames 
can not be blown out even though the oxygen density is low and the flow 
velocity increases because the recirculating gas is flown back at a high 
temperature and a temperature at the ignition point can not be easily 
lowered. Also, the drying or foaming process in the thermal equipment 
consumes the heat of the recirculating gas current, and hence the balanced 
temperature in the out-of-furnace circulating path does not increase. 
Here, adopting a pair of burners which alternately perform combustion as 
the above-mentioned burner causes alternate combustion and the 
recirculating gas current whose direction periodically changes in 
synchronism with the alternate combustion in the deodorizing furnace to 
improve the mixing of the gas in the deodorizing furnace and to smooth 
(average) the temperature in the deodorizing furnace. Further, 
incineration or thermal decomposition of the odor components can be 
efficiently performed in the wide area in the deodorizing furnace, and 
reduction in NOx can be also realized. Furthermore, according to this 
deodorizing system, since averaging the temperature in the deodorizing 
furnace and improving the mixing state of the gas contribute to make the 
volume ratio of the furnace space, which is effective for incineration or 
thermal decomposition of the odor gas in the deodorizing furnace, larger 
than that of the prior art, reduction in the volume of the deodorizing 
furnace or enhancement of the processing ability is possible, thereby 
reducing the size of the deodorizing furnace. 
Further, in the deodorizing system according to the present invention, the 
circulating opening is formed in the vicinity of the burner or it takes 
the form of a burner throat of the burner. In this case, the recirculating 
gas current including the odor components generated in the thermal 
equipment is assuredly mixed in the flames, and hence combustion or 
thermal decomposition of the odor components can be attained in a 
relatively-small space. Therefore, the volume of the deodorizing furnace 
can be reduced. 
In addition, the circulating fan is provided between the regenerator and 
the thermal equipment and on both the upstream side and the downstream 
side of the thermal equipment, respectively, in the deodorizing system 
according to the present invention. In such a case, gas circulation 
between the deodorizing furnace and the thermal equipment can be realized 
without being interfered with incursion of the air current into the 
thermal equipment. 
Moreover, the deodorizing system according to the present invention has a 
circulation amount adjusting damper and a dust collector provided on the 
upstream side of the thermal equipment in the out-of-furnace circulating 
path. According to this deodorizing system, a required quantity of the 
recirculating gas is taken out from the deodorizing furnace to the 
out-of-furnace circulating path in the thermal equipment such as a hot-air 
drier oven or a foaming oven. Further, dust components contained in the 
recirculating gas are collected by the dust collector before being led 
into the thermal equipment and then supplied as clean hot air having a 
medium/low temperature. Thus, this does not adversely influence operations 
performed in the thermal equipment, such as the drying or foaming 
operation. Also, an appropriate quantity of the gas current required in 
the thermal equipment such as a hot-air drier or a foaming oven can be 
supplied by adjusting a quantity of the recirculating gas current. 
Furthermore, the deodorizing system according to the present invention 
provides a bypass means for directly connecting the upstream and the 
downstream of each regenerator in order that part or all of the 
recirculating gas bypasses the regenerator and flows into the 
out-of-furnace circulating path to enable temperature adjustment. In this 
case, changing allotment of the recirculating gas current passing through 
the regenerator and the counterpart bypassing through the bypass means can 
readily adjust a temperature of the recirculating gas to be supplied to 
the thermal equipment. 
In addition, the deodorizing system according to the present invention is 
provided with a mist capturing means at a position close to the thermal 
equipment of each regenerator, i.e., on the low-temperature side of each 
regenerator. In this case, the mist carried by the exhaust from the 
thermal equipment is captured by the mist capturing means before passing 
through the regenerator and then dried to become dusts when the 
recirculating gas taken out from the deodorizing furnace passes through 
the regenerator. Accordingly, it is possible to prevent the mist from 
entering in the deodorizing furnace and the recirculating gas can be kept 
clean by periodically disposing the dusts. 
In the deodorizing system according to the present invention, it is 
preferable to use a regenerative burner system provided with regenerators 
for alternately burning a pair of burners which supply combustion air from 
the outside of the deodorizing furnace through the regenerators or exhaust 
combustion exhaust gas to the outside of the deodorizing furnace. In this 
case, when exhausting the combustion gas, since its sensible heat is 
recovered in the regenerators and again used for preheating the combustion 
air with an extremely high thermal efficiency to be returned to the inside 
of the furnace, a temperature of the combustion air can be a high 
temperature close to a temperature of the combustion exhaust gas that 
flows out toward the regenerators, and the high thermal efficiency can be 
maintained. Further, combustion of the burners is carried out by using the 
combustion air which does not relate to the gas circulating between the 
deodorizing furnace and the thermal equipment, and the odor gas having a 
low oxygen density in the exhaust gas flowing back from the thermal 
equipment can be also deodorized. 
In addition, in the deodorizing system according to the present invention, 
there may be provided a burner which has a fuel nozzle for blowing fuel in 
synchronism with changeover of a direction of the gas current and uses as 
the combustion air a part of the recirculating gas that circulates the 
out-of-furnace circulating path and has an oxygen density enough for 
maintaining stable combustion, and an exhaust means for exhausting gas 
that is generated by combustion and incurred air on the upstream side of 
the thermal equipment. According to this deodorizing system, when the 
oxygen density of the gas flowing back from the thermal equipment is 
enough for maintaining stable combustion because of incurred air, fuel can 
be burned by only injecting a part of the recirculating gas from the 
circumference of the fuel nozzle. 
Moreover, in this deodorizing system, it is preferable to provide a gas 
current restricting orifice and a throat so as to supply the recirculating 
gas having a range of optimum air ratio suitable for a quantity of fuel 
injection from the circumference of the fuel nozzle. In this case, a 
quantity of combustion in the deodorizing furnace can be controlled by 
only adjusting fuel injection. According to this invention, a quantity of 
combustion in the deodorizing system can be controlled by only adjusting a 
quantity of fuel injection because the recirculating gas having a range of 
optimum air ratio suitable for the injection quantity is supplied from the 
circumference of the fuel nozzle. 
Further, the deodorizing system according to the present invention 
comprises an air quantity adjusting damper and a regenerator, and the 
deodorizing system may provide a pair of changeover regenerative burners 
for alternately burning a pair of burners which supply combustion air 
through the regenerator or exhaust combustion gas in synchronism with 
changeover of a direction of the gas current and provide on the upstream 
side of the thermal equipment an exhaust means for supplying as combustion 
air the exhaust having an oxygen density that is exhausted from the 
thermal equipment in the out-of-furnace circulating path on the upstream 
side of each air quantity adjusting damper and enough for maintaining 
stable combustion and for exhausting only combustion generated gas and 
incurred gas. 
According to this deodorizing system, since the recirculating gas current 
having a predetermined temperature required in the thermal equipment can 
be obtained by the overall out-of-furnace circulating path even though 
heat exchange is carried out with taking into account only the temperature 
efficiency in the regenerator of the regenerative burner, the high thermal 
efficiency can be obtained, and a low-temperature damper can be used 
because the recirculating gas passing through the air quantity adjusting 
damper has a low temperature. 
In any of the above-mentioned deodorizing systems according to the present 
invention, since only the combustion gas generated due to an increase in 
heat and the air incurred into the thermal equipment are exhausted gas 
generated in the overall system and they are exhausted at an extremely low 
temperature, it is possible to attain the high thermal efficiency which 
can not be obtained in the prior art deodorizing system.

BEST MODES FOR EMBODYING THE INVENTION 
The configuration of the present invention will now be described hereunder 
in detail in conjunction with illustrative embodiments. 
FIG. 1 shows an embodiment in which the present invention is applied to a 
preferred deodorizing system for deodorizing odor gas having a low oxygen 
density. This deodorizing system is mainly composed of a deodorizing 
furnace 1 provided with at least a pair of burners 3A and 3B which 
alternately perform combustion, an out-of-furnace circulating path 4 for 
temporarily taking out combustion gas generated in the deodorizing furnace 
1 and again flowing it back from another position into the deodorizing 
furnace 2, and a thermal equipment 8 constituting a part of the 
out-of-furnace circulating path 4 and using a gas current having a 
medium/low temperature as a heat source, and gas containing the odor 
generated in the thermal equipment 8 is burnt and removed in the 
deodorizing furnace 1 by recirculating the gas current between the thermal 
equipment 8 and the deodorizing furnace 1. 
The out-of-furnace circulating path 4 is provided with a pair of 
circulating openings 9A and 9B, regenerative beds 5A and 5B as a pair of 
regenerators, circulating fans 6 and 10, a passage switching means 7 for 
selectively and alternately connecting the circulating fans 6 and 10 with 
one of the regenerative beds 5A and 5B to switch a direction of a flow of 
a gas current toward the regenerative beds 5A and 5B, and a thermal 
equipment 8 utilizing a gas current having a medium/low temperature as a 
heat source in order that a strong recirculating current (indicated by 
arrows) whose gas current direction is periodically inverted in accordance 
with changeover of combustion of the pair of burners 3A and 3B of the 
deodorizing furnace 1 is formed in the deodorizing furnace 2. Here, the 
strong recirculating current means a recirculating gas current having a 
volume much larger than that of the supplied gas current. 
The passage switching means 7 is positioned between the deodorizing furnace 
1 and an intake of the circulating fan 6 and between the deodorizing 
furnace 1 and an outlet of the circulating fan 10 and provided in such a 
manner that ducts 23A and 23B communicating with two circulating openings 
9A and 9B provided to the deodorizing furnace 1 be connected to two (two 
ports provided at positions where these two ports do not communicate with 
each other) out of four ports while the intake of the circulating fan 6 
and the outlet of the circulating fan 10 be connected with the remaining 
two ports and that one of the circulating openings 9A and 9B be connected 
with the circulating fan 6 while the other be connected with the 
circulating fan 10. The circulating openings 9A and 9B formed in the 
deodorizing furnace 2 of the out-of-furnace circulating path 4 are 
arranged in the vicinity of respective burner throats of the burners 3A 
and 3B so that the recirculating gas current flowing back from the thermal 
equipment 8 collides with flames and combustion gas. It is to be noted 
that the passage switching means 7 is not restricted to a four-way valve 
and it can be substituted by any other passage switching means having the 
same function. In addition, the passage switching means 7 is connected 
with a control four-way valve 12 for alternately burning the pair of 
burners 3A and 3B by means of a link or the like, and the passage 
switching means 7 and the four-way valve 12 can be switched in synchronism 
with each other. 
Further, the out-of-furnace circulating path 4, having the regenerative 
beds 5A and 5B as the regenerators in the vicinity of the circulating 
openings 9A and 9B provided to the deodorizing furnace 1, recovers a part 
of sensitive heat of combustion exhaust gas taken out from the deodorizing 
furnace 1 by the regenerative beds 5A and 5B and circulates it after 
turning into a gas current having a medium/low temperature suitable for 
being used in the thermal equipment 8. Furthermore, it again turns it into 
a high-temperature gas current by direct heating in the regenerative beds 
5A and 5B when flowing it back into the deodorizing furnace 1. Here, 
either the intake side of the circulating fan 6 or the outlet side of the 
circulating fan 10 is selectively connected with the respective 
circulating openings 9A and 9B through the passage switching means 7, and 
the combustion exhaust gas taken out from the deodorizing furnace 1 
through one of the regenerative beds 5A and 5B is supplied to the thermal 
equipment 8 while the exhaust containing odor gas generated in the thermal 
equipment, namely, the recirculating gas is flowed back to the deodorizing 
furnace 1. It is to be noted that a circulation quantity adjusting damper 
18 for adjusting a quantity of the recirculating gas current and a dust 
collector 19 are provided between the circulating fan 6 and the thermal 
equipment 8. Dusts and others are removed and an appropriate quantity of 
the dean recirculating gas current is supplied to the thermal equipment 8. 
The circulation quantity adjusting damper 18 flows the 
medium/low-temperature combustion exhaust gas, i.e., the recirculating gas 
whose quantity is required in the thermal equipment 8. Further, a dust 
collector for a low temperature such as a bag filter may be used as the 
dust collector 19. 
Also, a furnace pressure adjusting damper 20 is provided between the 
thermal equipment 8 and the circulating fan 10. The furnace pressure 
adjusting damper 20 balances an exhausting quantity and a recirculating 
quantity of the gas by maintaining the atmospheric pressure or a pressure 
slightly-lower than the atmospheric pressure in the thermal equipment 8. 
This prevents the odor gas generated in the thermal equipment 8 from 
leaking outside the system. It is to be noted that the thermal equipment 8 
uses the gas current having a medium/low temperature as a heat source to 
apply a predetermined process such as a drying or foaming process on the 
work W. 
A bypass 21 is provided to each of the regenerative beds 5A and 5B of the 
out-of-furnace circulating path 4, and a temperature adjusting bypass 
damper 22 is disposed to the bypass 21. The temperature adjusting bypass 
damper 22 flows a part of the combustion exhaust gas, i.e., the 
recirculating gas taken out from the deodorizing furnace 1 to the passage 
switching means 7 without passing through the regenerative beds 5A and 5B 
and adjusts the recirculating gas to have a desired temperature by mixing 
the recirculating gas and the gas which has passed through the 
regenerative beds 5A and 5B. 
Further, a regenerative burner system is adopted as a pair of burners 3A 
and 3B attached to the deodorizing furnace 1 in this embodiment. The 
regenerative burner system selectively and alternately connects the pair 
of burners 3A and 3B having regenerators which are regenerative beds 11A 
and 11B to an air supply system 13 or an exhaust system 14 through a 
passage switching means 12 in order that one of the two burners 3A and 3B 
performs combustion while the other which is not burning exhausts a large 
part of combustion gas which has been used for combustion or thermal 
decomposition of odor components contained in the recirculating gas. The 
respective burners 3A and 3B are provided on, e.g., the both side walls of 
the deodorizing furnace 1 so as to be opposed to each other and they 
alternately operate. Note that the burners 3A and 3B do not have to be 
separately arranged on the both side walls of the deodorizing furnace 1 so 
as to be opposed to each other, and they may be provided on, e.g., one 
wall of the deodorizing furnace 1 according to circumstances. 
Incidentally, reference numeral 16 denotes a fuel nozzle in the drawing. 
The regenerative beds 11A and 11B are accommodated in burner bodies, 
different casings or the like and incorporated in the burners 3A and 3B, 
respectively. The regenerative beds 11A and 11B perform heat exchange with 
the combustion exhaust gas passing therethrough to recover the wasted heat 
and preheat the combustion air by using the recovered heat. The 
regenerative beds 11A and 11B of the respective burners 3A and 3B are 
connected with two (two ports provided at position where they do not 
communicate with each other) out of four ports of the four-way valve 12 
through ducts 15. Further, an air supply system 13 and an exhaust system 
14 are connected with two remaining ports of the four-way valve 12. As to 
the burners 3A and 3B and the regenerative beds 11A and 11B, one burner 
and one regenerative bed are connected with the air supply system 13 while 
the remaining burner and regenerative bed are connected with the exhaust 
system 14, their connection can be switched by changing over the four-way 
valve 12. Note that the four-way valve 12 and the passage switching means 
7 are changed over in synchronism with each other. 
Here, it is preferable to use the structure and material whose pressure 
loss is relatively low but heat capacity is large and which have the 
improved durability, e.g., a ceramic cylindrical body which has a 
plurality of cells and a honey-comb shape for the regenerative beds 11A 
and 11B used in the burners 3A and 3B and the regenerative beds 5A and 5B 
provided in the out-of-furnace circulating path 4. For example, a 
honey-comb-shaped member manufactured by extrusion-molding the ceramic 
material such as cordierite or mullite may be preferably used for heat 
exchange between a fluid having a high temperature of approximately 
1000.degree. C. such as the combustion exhaust gas and a counterpart 
having a relatively-low temperature of approximately 20 through 
200.degree. C. such as the combustion air or the odor gas. Further, as a 
honey-comb-shaped regenerative bed, it may be possible to employ a 
material other than aluminum or ceramics, e.g., a metal such as a 
heat-resisting steel or a complex of ceramics and a metal, e.g., an 
Al.sub.2 O.sub.3 --Al complex or an SiC--Al.sub.2 O.sub.3 --Al complex 
whose pores are completely filled up. This type of complex can be 
manufactured by causing the melted metal to spontaneously penetrate into 
pores of the ceramics having a porous structure, oxidating or nitriding a 
part of that metal to turn into ceramics. It is to be noted that the 
honey-comb shape essentially indicates hexagonal cells (holes) but it 
includes the structure having square or triangular cells as well as 
hexagonal cells formed thereto in this specification. In addition, the 
honey-comb-shaped regenerative bed may be obtained by bundling tubes or 
the like without performing integral molding. However, the shapes of the 
regenerative beds 5A, 5B, 11A and 11B are not restricted to the honey-comb 
shapes, and flat-plate-type or corrugated-plate-type regenerative 
materials may be radially arranged in a cylindrical casing or pipe-like 
regenerative materials may be filled in a cylindrical casing in such a 
manner that the fluid can pass through the materials in the axial 
direction. Further, a cylindrical casing in which two chambers are formed 
by a partition wall in the circumferential direction and the fluid can 
pass in the axial direction may be prepared, and the regenerative bed may 
be constituted by filling a lump of the spherical, short-pipe-like, 
short-rod-like, small-piece-type, nugget-type or net-type regenerative 
material in each of the chambers. 
According to the deodorizing system having the above-mentioned arrangement, 
using only a heat source of the deodorizing furnace 1 can realize 
operation of the thermal equipment 8 and deodorization of the gas 
containing the odor generated in the thermal equipment 8 in the following 
manner. 
A non-stationary flame is formed in the furnace 2 by alternately burning 
the pair of burners 3A and 3B in the deodorizing furnace 1 in order to 
burn or thermally decompose the odor components in the recirculating gas 
flowing back from the thermal equipment 8 by using the combustion heat. 
Here, the burners 3A and 3B are switched in a short period of, e.g., not 
more than 60 seconds, or more preferably, approximately 20 seconds or a 
shorter time. The changeover of combustion is performed by turning on/off 
injection of fuel and switching the four-way valve 12 for the combustion 
air. The combustion air is preheated by the regenerative bed 11A or 11B 
having heated by heat of the exhaust gas and comes to have an 
extremely-high temperature (for example, approximately 800 through 
1000.degree. C.). When the combustion air has such a high temperature, a 
temperature of the mixed gas itself approximates to or becomes higher than 
a temperature of self ignition of the fuel even though the oxygen density 
is low, and an increase in a response speed or a prominent extension of 
combustible limit largely contribute stability of combustion, resulting in 
the excellent combustion. Therefore, incineration or thermal decomposition 
of the odor components is possible without hindering combustion even 
though the oxygen density of the recirculating gas flowing back from the 
thermal equipment 8 is low. Also, since the recirculating gas flowing back 
from the thermal equipment 8 comes to have a high temperature by heat 
exchange performed between the regenerative beds 5A and 5B, a temperature 
at an ignition point is not extremely lowered even if the recirculating 
gas current collides with a flame 17, whereby the flame is not blown off. 
Meanwhile, on the burner connected to the exhaust system 14, the combustion 
gas which has been used for burning or thermally decomposing the odor 
components is exhausted to the outside of the furnace through the burner 
throat. Here, the sensible heat of the exhaust gas is recovered by the 
regenerative bed 11A or 11B in order that the exhaust gas has a low 
temperature, and the exhaust gas is then exhausted through the exhaust 
system 14. 
At the same time, a part of the combustion gas is taken out to the 
out-of-furnace circulating path 4 through one of the circulating openings 
9A and 9B as the recirculating gas and used as a heat source of the 
thermal equipment 8. Thereafter, it is again flowed back from the 
remaining circulating opening 9A or 9B to the deodorizing furnace 1. That 
is, a part of the atmosphere gas in the deodorizing furnace 2 circulates 
between the deodorizing furnace 1 and the thermal equipment 8 via the 
out-of-furnace circulating path 4. For example, in the state shown in FIG. 
1, the combustion gas in the deodorizing furnace 2 is taken out to the 
out-of-furnace circulating path 4 through the regenerative bed 5B of the 
circulating opening 9B by a negative pressure generated by the circulating 
fan 6. In this process, a part of the sensible heat of the recirculating 
gas current is wasted in the regenerative bed 5B and the recirculating gas 
current comes to have a desired temperature in order that this current can 
be used in the thermal equipment 8. Here, the full quantity of the 
recirculating gas current does not necessarily pass through the 
regenerative bed 5B and a part of the recirculating gas current passes 
through the temperature adjusting bypass damper 22 if necessary. The 
recirculating gas current which has passed through the regenerative bed 5B 
on the downstream side thereof so as to have a low temperature is mixed 
with the recirculating gas current which has bypassed the regenerative bed 
5B to maintain a high temperature in order to generate the recirculating 
gas having a temperature (medium/low temperature) required in the thermal 
equipment 8. For example, the combustion exhaust gas having a temperature 
of 800.degree. C. is taken out from the deodorizing furnace 1 to generate 
the recirculating gas current having a temperature of 300.degree. C. This 
recirculating gas current is led into the thermal equipment 8 via the 
passage switching means 7, the circulating fan 6, the circulation quantity 
adjusting damper 18 and the duct collector 19 in the mentioned order. This 
recirculating gas current is then used for a predetermined process such as 
a drying or foaming process. 
The recirculating gas current having been used for the operation in the 
thermal equipment 8 is taken out from the thermal equipment 8 by an 
induced draft fan 10, passes through the furnace pressure adjusting damper 
20 and the passage switching means 7 in the mentioned order, and flows 
back from the circulating opening 9A of the burner 3A performing 
combustion into the deodorizing furnace 1. Here, the recirculating gas 
current is heated by the regenerative bed 5A to again have a high 
temperature and flowed back into the deodorizing furnace 1. For example, 
even if a temperature of the recirculating gas current is lowered to 
approximately 200.degree. C. when it is taken out from the thermal 
equipment 8, the recirculating gas current is heated to have a temperature 
of approximately 700.degree. C. by passing through the regenerative bed 5A 
so that this gas current be returned into the deodorizing furnace 1 
assuming that the air or the like entered into the thermal equipment 8 can 
be ignored. 
As mentioned above, since the deodorizing system according to the present 
invention recovers a part of the sensible heat of the gas in the 
deodorizing furnace by the regenerative beds 5A and 5B to generate a gas 
current having a medium/low temperature which can be used in the thermal 
equipment 8 and returns the recirculating gas containing the odor 
components exhausted from the thermal equipment 8 into the deodorizing 
furnace 1 after turning the recirculating gas into a high-temperature gas 
again by utilizing the recovered heat, the temperature can not be largely 
lowered even though the recirculating gas containing the odor is mixed 
with the combustion gas or the flame, and the non-stationary flame 
generated due to alternate combustion contributes to make the temperature 
distribution in the furnace uniform, thereby attaining incineration or 
thermal decomposition of the odor components in a short time. Further, 
occurrence of no local high-temperature area reduces NOx to be generated. 
It is to be noted that the above has described a preferred embodiment of 
the present invention, but the invention is not restricted thereto and 
various modifications or other embodiments are possible within a true 
scope and spirit of the invention. For example, description has been given 
as to the invention applied to the regenerative burner system, i.e., a 
heat source which uses the combustion air different from the gas 
circulating in the out-of-furnace circulating path 4 to alternately burn 
the pair of burners 3A and 3B in the foregoing embodiment. However, the 
present invention is not restricted to the above application, and any 
other regenerative burner or an usual burner such as shown in FIGS. 2 and 
3 may be used, for example. 
FIG. 2 shows another embodiment of a deodorizing system which is preferable 
to exhaust the gas which contains the odor components and has a high 
oxygen density from the thermal equipment, for example. This example has a 
configuration such that burner throats 25A and 25B of a pair of 
regenerative burners 3A and 3B which alternately perform combustion are 
connected with ducts 23A and 23B of the regenerative beds 5A and 5B of the 
out-of-furnace circulating path 4 on the downstream side through ducts 26A 
and 26B so that a part of the recirculating gas current be supplied to the 
burners 3A and 3B and utilized as the combustion air. Only the fresh air 
entering into the thermal equipment 8 is supplied as the combustion air. 
The burner throats 25A and 25B of the regenerative burners 3A and 3B are 
connected with the out-of-furnace circulating path 4 through the ducts 26A 
and 26B on the downstream side of the regenerative beds 5A and 5B. In 
addition, air quantity adjusting dampers 27 for adjusting a quantity of 
the combustion air are provided to the connecting ducts 26A and 26B. 
Moreover, the exhaust system 29 is connected on the upstream side of the 
thermal equipment 8, or more preferably, between the downstream side of 
the dust collector 19 and the thermal equipment 8 through the exhaust 
adjusting damper 28, and a part of the recirculating gas current, i.e., 
the increased air generated by combustion and the incurrent air are wasted 
as the excessive air. The recirculating gas including the combustion gas 
which has been used for incineration or thermal decomposition of the odor 
components in the deodorizing furnace 1 is partially subjected to heat 
recovery in the regenerative bed 11A or 11B of either the burner 3A or 3B 
which is not currently performing combustion and then led to the 
downstream side of the regenerative bed 5A or 5B of the out-of-furnace 
circulating path 4. At the same time, the combustion gas is partially 
taken out to the out-of-furnace circulating path 4 through the circulating 
opening 9A or 9B and passes through the regenerative bed 5A or 5B where 
the combustion gas is cooled down to have a predetermined temperature. 
This gas is thereafter supplied to the thermal equipment 8. It is then 
used as a heat source of the thermal equipment 8 and flowed back to the 
deodorizing furnace 1 again. In other words, the combustion exhaust gas 
containing the recirculating gas circulates between the deodorizing 
furnace 1 and the thermal equipment 8 through the out-of-furnace 
circulating path 4, meanwhile the burners 3A and 3B of the deodorizing 
furnace 1 alternately carry out combustion. 
According to the deodorizing system having the above-mentioned arrangement, 
a part of the combustion gas in the deodorizing furnace 2 passes through 
the regenerative bed 11B of the burner 3B which is not currently 
performing combustion and taken out to the out-of-furnace circulating path 
4 and the remaining part of the same is taken out to the out-of-furnace 
circulating path 4 via the regenerative bed 5B of the circulating opening 
9B in the state shown in FIG. 2. During this process, the sensible heat of 
the recirculating gas is partially recovered in the respective 
regenerative beds 11B and 5B to obtain a desired temperature which can be 
used in the thermal equipment 8. Here, the recirculating gas current 
partially passes through the temperature adjusting bypass damper 21 if 
necessary. The recirculating gas which has passed through the regenerative 
beds 5B and 11B on the downstream side of the regenerative bed 5B to have 
a low temperature is mixed with the recirculating gas which has bypassed 
the regenerative bed 5B to maintain a high temperature in order to 
generate the recirculating gas current having a desired temperature. This 
recirculating gas current is led into the thermal equipment 8 through the 
passage switching means 7, the circulating fan 6, the circulation quantity 
adjusting damper 18 and the dust collector 19 in the mentioned order. The 
recirculating gas current is then used for a predetermined process such as 
a drying or foaming process in the thermal equipment 8. The recirculating 
gas which has been used for the operation in the thermal equipment 8 is 
taken out from the thermal equipment 8 by the induced draft fan 10 and 
passes through the furnace pressure adjusting damper 20 and the passage 
switching means 7 in the mentioned order. A part of the recirculating gas 
is then adjusted to have a desired air quantity and supplied from the duct 
26A communicating with the burner throat 25A of the burner 3A which is 
performing combustion so as to be used as the combustion air. Further, the 
remaining part of the same passes through the regenerative bed 5A to again 
have a high temperature and then flows back from the circulating opening 
9A to the deodorizing furnace 2. In this deodorizing system, since the air 
quantity adjusting means, i.e., the both dampers 27 and 18 are provided at 
positions where a temperature of the recirculating gas current is low, a 
general low-temperature damper can be used. In particular, even if the air 
quantity adjusting damper 27 positioned in each of the ducts 26A and 26B 
is used and a temperature obtained by heat recovery in the regenerative 
beds 11A and 11B is set lower than that required in the thermal equipment 
8 with taking into account only the temperature efficiency, the 
recirculating gas is mixed with the counterpart having a higher 
temperature on the downstream side in a subsequent process. Therefore, the 
recirculating gas current having a predetermined temperature required in 
the thermal equipment 8 can be obtained in the overall out-of-furnace 
circulating path. 
Further, when exhausting the gas which contains the odor gas components and 
has a high oxygen density from the thermal equipment 8, a deodorizing 
system such as shown in FIG. 3 can be also embodied. In this embodiment, 
regular burners 3A' and 3B' having no regenerative bed attached thereto 
are used as the burners and burner throats 25A' and 25B' are connected 
with the upstream sides of the regenerative beds 5A and 5B of the 
out-of-furnace circulating path 4 through ducts 30A and 30B in order to 
supply a part of the recirculating gas current to the burners 3A' and 3B' 
as the combustion air. Only the fresh air entering into the thermal 
equipment 8 is supplied as the combustion air. The burner throats 25A' and 
25B' of the burners 3A' and 3B' are connected with the respective ducts 
23A and 23B of the out-of-furnace circulating path 4 on the upstream sides 
of the regenerative beds 5A and 5B, respectively. Further, combustion air 
restricting orifices 31 for adjusting a quantity of the combustion air are 
provided to the connecting ducts 30A and 30B, respectively. Moreover, the 
exhaust system 29 is connected on the upstream side of the thermal 
equipment 8, or more preferably between the downstream side of the dust 
collector 19 and the thermal equipment 8 through the exhaust adjusting 
damper 28, and the increased quantity of the recirculating gas, i.e., the 
combustion gas generated from combustion and the air entering into the 
thermal equipment 8 are wasted as the excessive gas. 
According to the deodorizing system having the above-mentioned arrangement, 
the combustion gas in the deodorizing furnace 2 is taken out to the 
out-of-furnace circulating path 4 through the circulating opening 9B and 
the burner throat 25B' of the burner 3B' which is not currently performing 
combustion and circulates in the state shown in FIG. 3. During this 
process, the sensible heat of the combustion gas is partially recovered in 
the regenerative bed 5B to have a desired temperature which can be used in 
the thermal equipment 8. The recirculating gas which has been used for a 
predetermined process such as a drying or foaming process in the thermal 
equipment 8 is taken out from the thermal equipment 8 by the induced draft 
fan 10 and heated by the regenerative bed 5A to again have a high 
temperature. A part of this gas is then flowed back from the circulating 
opening 9A into the deodorizing furnace 2 and the remaining part of the 
same is supplied to the burner throat 25A' through the duct 30A and the 
orifice 31 as the combustion air to burn the fuel injected from the fuel 
nozzle 16. Injection of the fuel and the air is switched at predetermined 
time intervals for alternate combustion of the burners 3A' and 3B'. 
Further, the gas flowing out from the deodorizing furnace 1 or the thermal 
equipment 8 such as a foaming oven is dirty gas containing a large amount 
of mist, and hence the mist should be removed. As a countermeasure, it is 
preferable to provide a mist capturing means 24 such as shown in FIG. 4 on 
the downstream sides of the regenerative beds 5A and 5B of the respective 
deodorizing systems, e.g., at positions indicated by broken lines in FIGS. 
1 through 3. The mist capturing means 24 comprises an air-permeable case 
32 such as a punching metal case which can be put into and removed from 
the ducts 23A and 23B constituting the out-of-furnace circulating path 4 
in a direction across a flow of the recirculating gas current without 
restraint and an air-permeable filling 33 such as metal chips accommodated 
in the case 32, for example. 
When the mist capturing means 24 is provided on a position which is close 
to the thermal equipment 8 of each of the regenerative beds 5A and 5B and 
where the relatively-low-temperature gas flows, the mist in the gas can be 
attracted to the air-permeable filling 33 and removed when the 
non-deodorized recirculating gas including the odor components from the 
thermal equipment 8 passes through such a means. The mist captured by the 
mist capturing means 24 is dried and turned into dusts when the deodorized 
dry gas, i.e., the recirculating gas supplied from the deodorizing furnace 
1 passes by switching the flow direction of the gas current. Repeating 
this process in accordance with periodical changeover of the flow of the 
gas current causes the dusts to be deposited to the mist capturing means 
24. It is enough to periodically take out the case 32 from the ducts 23A 
and 23B and clean the filling 33. 
In addition, although the above has mainly described the respective 
embodiments in which a combination of a pair of regenerative burners which 
alternately perform combustion is adopted as a heat source, the present 
invention is not restricted to this structure, and one burner may 
continuously effect combustion. In this case, it is preferable to arrange 
the burner so as to blow the recirculating gas injected from the pair of 
circulating openings 9A and 9B to the flame. Further, a heat source such 
as a radiant tube burner may be employed.