KR101292233B1 - Waste treating system - Google Patents

Abstract

The waste disposal system which can suppress generation | occurrence | production of nitrous oxide can be provided. The waste treatment system includes a pyrolysis furnace for pyrolyzing organic waste, a combustion furnace for combusting flammable pyrolysis gas generated in the pyrolysis furnace, a heat utilization device using a combustion exhaust gas generated in the combustion furnace as a heat source, and heat The combustion exhaust gas used by the utilization apparatus and the temperature fell is refluxed as combustion air to a combustion furnace, and has a reflux line.

Description

Waste Treatment System {WASTE TREATING SYSTEM}

Embodiments of the present invention relate to a waste treatment system for treating organic waste.

In a waste treatment system for treating organic waste such as dewatered sludge, the organic waste is thermally decomposed in a low oxygen state in a pyrolysis furnace, and the organic waste is separated into a pyrolysis gas and a pyrolysis residue. In addition, the waste treatment system combusts flammable pyrolysis gas in a combustion furnace, and uses this combustion exhaust gas as a heat source of a heat utilization device. The combustion exhaust gas loses heat energy in the heat utilization device, and the temperature drops, and the combustion exhaust gas is discharged as the low temperature combustion exhaust gas.

Conventional waste treatment systems described in Japanese Patent No. 4198426 and Japanese Patent Application Laid-Open No. 2007-270018 produce nitrous oxide (N ₂ O), which is a greenhouse gas when organic nitrogen is included in organic waste. do. Nitrous oxide is a substance which adversely affects the global environment, and a substance which increases so-called environmental load. Therefore, the emission must be restrained as much as possible.

An object of the present invention is to provide a waste treatment system capable of suppressing the generation of nitrous oxide.

The waste treatment system of the embodiment includes a pyrolysis furnace that receives organic waste and thermally decomposes the organic waste in a high-temperature reducing atmosphere, a combustion furnace that combusts flammable pyrolysis gas generated in the pyrolysis furnace, and the combustion furnace One or a plurality of heat using apparatuses using combustion exhaust gas generated as a heat source and low-temperature exhaust gas after heat use, which is used by the heat using apparatuses and whose temperature has decreased, upstream from the heat using apparatuses. And a reflux line for reflux to the apparatus arranged on the side, and used as combustion air or dilution air in the apparatus arranged on the upstream side.

According to the waste processing system of the said structure, generation | occurrence | production of nitrous oxide can be suppressed.

1 is a block diagram showing a waste treatment system according to a first embodiment;
2 is a diagram showing a relationship between a combustion temperature of a combustion furnace and N ₂ O concentration in a low temperature combustion exhaust gas;
3 is a block diagram showing a waste treatment system according to a second embodiment;
4 is a block diagram illustrating a waste treatment system according to a third embodiment;

The waste treatment system of the embodiment includes a thermal decomposition furnace for thermally decomposing organic waste in a high-temperature reducing atmosphere, a combustion furnace for combusting flammable pyrolysis gas generated in the thermal decomposition furnace, and combustion exhaust gas generated in the combustion furnace as heat sources. And a reflux line for refluxing the low-temperature exhaust gas after heat use, in which heat is used by the heat-use device and the temperature is lowered, as combustion air.

In the embodiment, the low temperature exhaust gas after heat use is refluxed to the combustion furnace by the reflux line, and the low temperature exhaust gas is used as part of the combustion air in the combustion furnace. When the low-temperature exhaust gas is used as part of the combustion air, the combustion temperature of the combustion furnace can be increased by the amount of the exhaust gas as compared with the case where only external air at ordinary temperature is used as the combustion air. As the combustion temperature in the combustion furnace rises, the amount of nitrous oxide produced in the combustion exhaust gas decreases. Since the combustion exhaust gas after heat use is much higher than outside air, it is suitable for being used as combustion air in a combustion furnace, and can greatly contribute to improving the heat utilization efficiency of the entire waste treatment system.

When the low-temperature exhaust gas is used as dilution air of the combustion exhaust gas discharged from the combustion furnace, the temperature of the combustion exhaust gas after combustion can be lowered. For this reason, even if there is an upper limit to the temperature of the combustion exhaust gas for reasons such as the material of the heat utilization apparatus, the temperature of the combustion exhaust gas introduced into the heat utilization apparatus can be lowered. When the combustion exhaust gas after heat use is used as dilution air, the amount of exhaust gas discharged | emitted out of a system can be reduced compared with the case where external air is used as dilution air. In addition, the heat utilization efficiency of the entire waste treatment system is improved.

In the waste disposal system of an Example, it is preferable that a combustion furnace suppresses generation | occurrence | production of nitrous oxide by burning a pyrolysis gas in the temperature range of 900 degreeC or more and 1000 degrees C or less. The N ₂ O concentration in the combustion exhaust gas decreases as the combustion temperature of the combustion furnace increases, but becomes nearly constant when the combustion temperature reaches 900 ° C or more. For example, comparing the N ₂ O concentration in the combustion exhaust gas when the combustion temperature is 870 ° C. and the N ₂ O concentration in the combustion exhaust gas when the temperature 900 ° C., the temperature difference is only 30 ° C., the latter N ₂ The O concentration drops sharply to almost half of the N ₂ O concentration of the former (see FIG. 2). If the combustion temperature is further increased to 950 ° C. or more, the N ₂ O concentration in the combustion exhaust gas hardly changes and becomes substantially constant (see FIG. 2). For this reason, in an Example, more preferably, a pyrolysis gas is combusted so that the combustion temperature of a combustion furnace may be 950 degreeC or more.

On the other hand, the design temperature of a combustion furnace is 1200 degreeC, and the material and structure which comprise a combustion furnace are designed to withstand the temperature. However, for reasons such as to prolong the life of the furnace, the actual combustion temperature when the furnace is operated is at most up to about 1000 ° C. For this reason, in an Example, the upper limit of the combustion temperature of a combustion furnace shall be 1000 degreeC.

It is preferable that the waste processing system of the Example further has a dryer which reduces the moisture content of organic waste arrange | positioned upstream rather than a thermal decomposition furnace. The dryer heats the organic waste to evaporate moisture from the organic waste, thereby reducing the moisture contained in the organic waste.

When the organic waste is heat-dried using a dryer to reduce the moisture content of the organic waste, there is an advantage that the thermal decomposition reaction of the organic waste proceeds quickly and smoothly in the thermal cracking furnace. In the case where a large amount of water such as activated sludge is treated as an organic waste, if it is sent directly to a pyrolysis furnace, the load of the pyrolysis furnace is increased because the weight of the organic waste to be heated is large. When the organic waste is dried in a dryer in advance and the weight is reduced, the load on the thermal decomposition furnace is reduced.

This dryer can be one of the apparatus arrange | positioned upstream using the heat which the low temperature combustion exhaust gas after heat is used by a heat utilization apparatus uses. That is, the low temperature combustion exhaust gas after using heat is supplied to the dryer upstream of a combustion furnace via a reflux line. As a result, the dryer can use low-temperature combustion exhaust gas. The temperature of the low temperature combustion exhaust gas discharged from the heat utilizing apparatus is 500 degrees C or less, and the process design temperature of a dryer is 100 degreeC-300 degreeC. The dryer can use various heat sources, and can use well-known general-purpose heating apparatuses, such as a heat exchanger, an electric resistance heating apparatus, and a combustion heating apparatus, in addition to low temperature combustion exhaust gas.

Moreover, the low temperature combustion exhaust gas after heat use is supplied to the thermal decomposition furnace upstream of a combustion furnace through the reflux line from the heat utilization apparatus arrange | positioned downstream of a combustion furnace. Accordingly, the pyrolysis furnace can use low temperature combustion exhaust gas. Process design temperatures for pyrolysis furnaces range from 300 ° C to 750 ° C.

It is preferable that a waste processing system further has a dust collector between a heat utilization apparatus and a combustion furnace (refer FIG. 3).

Sold out, which is a solid content generated in the combustion furnace, adheres to the inner wall of the heat-use device, thereby lowering the heat-use efficiency. For this reason, it is possible to prevent the deterioration of the heat utilization efficiency of the heat using apparatus by separating and removing the dust from the combustion exhaust gas using the dust collector. In addition, in this invention, a dust collector is not limited only to a specific type.

It is preferable that a waste processing system further has an auxiliary fuel supply apparatus which supplies an auxiliary fuel to a combustion furnace in order to compensate for the shortage of heat in a heat utilization apparatus (refer FIG. 4).

Due to various reasons such as incomplete combustion of a combustion furnace and abnormal operation of a pyrolysis furnace, the amount of heat of the combustion exhaust gas decreases, and the amount of heat may be insufficient in a heat-use device. In such a case, the calorific value can be compensated for by supplementing the auxiliary fuel from the auxiliary fuel supply device to the combustion furnace.

 Hereinafter, various exemplary embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(Embodiment 1)

A first embodiment will be described with reference to FIG. 1.

The waste disposal system 1 of this embodiment is equipped with the dryer 2, the thermal decomposition furnace 3, the combustion apparatus 4, and the heat utilization apparatus 5, as shown in FIG. The inside of the system of this processing system 1 is sucked and exhausted by the single or plural blower (not shown) arrange | positioned downstream. In addition, the whole of the processing system 1 is collectively managed and controlled by the process computer (not shown).

In the dryer 2, organic waste is thrown in through the waste supply line L1 from an upstream waste input device (not shown). The dryer 2 heats organic waste to predetermined temperature of 100 to 300 degreeC, and removes moisture from organic waste. The dryer 2 can use various heat sources. As a heat source, well-known general purpose heating apparatuses, such as low-temperature combustion exhaust gas after heat is used by the downstream heat utilization apparatus 5, a fruit, an electric resistance heating apparatus, and a combustion heating apparatus, can be used. In addition, the waste supply line L1 includes a belt conveyor, a meter, a shooter and a hopper, for example.

The pyrolysis furnace 3 thermally decomposes organic waste in a reducing atmosphere. The pyrolysis furnace 3 is a horizontal kiln-type or screw feeder-type horizontal arrangement apparatus having a hollow shaft chamber 31 which is rotationally driven and a heating jacket 32 for heating it. The hollow shaft chamber 31 is rotatably supported by a rotation drive mechanism (not shown). Organic waste is supplied to the hollow part of the hollow shaft chamber 31 from the dryer 2 via the waste supply line L2. The organic waste in the hollow shaft chamber 31 is heated by the fruit which passes through the heating jacket 32, and decompose | disassembles into a thermal decomposition gas and a thermal decomposition residue. The outlet end part downstream of the hollow shaft chamber 31 is connected to the upper end burner 43 of the combustion furnace 4 via the pyrolysis gas line L3. The pyrolysis gas is discharged from the hollow shaft chamber 31 through the pyrolysis gas line L3 and introduced into the combustion furnace 4. Moreover, the carbide discharge line L8 is provided in the downstream position of the hollow shaft chamber 31, and the carbide which is the residue after thermal decomposition through the carbide discharge line L8 is discharged | emitted from the hollow shaft chamber 31. Moreover, as shown in FIG. do.

The heating jacket 32 is a jacket container surrounding at least a part of the hollow shaft chamber 31. The fruit supply pipe 33 and the fruit discharge pipe 34 are connected to the heating jacket 32. Hot air, for example 300 ° C. to 750 ° C., dry air is supplied into the heating jacket 32 as a fruit through the fruit supply pipe 33 from the fruit source. The fruit is discharged from the heating jacket 32 through the fruit discharge pipe 34 after heating the organic waste in the hollow shaft chamber 31. In addition, the fruit supply pipe 33 and the fruit discharge pipe 34 may be connected by a return line to form a circulation circuit, and the used fruit may be repeatedly used in the thermal decomposition furnace. Moreover, as a heat source of the thermal decomposition furnace 3, well-known general purpose heating apparatuses, such as an electric resistance heating apparatus or a combustion heating apparatus, can be used. It is most suitable to use the combustion exhaust gas discharged from the combustion furnace 4 of a next process as a heat source from an economical viewpoint. In addition, a well-known general purpose measuring instrument, such as a thermocouple, is used for a temperature measuring apparatus (not shown).

The combustion furnace 4 is equipped with the combustion injection type burner at one end in the combustion apparatus of thermal decomposition gas. The pyrolysis gas line L3 and the combustion air line (not shown) are connected to the burner, the flammable pyrolysis gas and the combustion air are spray mixed at a predetermined ratio to burn the pyrolysis gas. The combustion furnace 4 is provided with the discharge port 41 which communicates with the combustion exhaust gas line L4 at the other end. The combustion exhaust gas line L4 branches into two lines L41 and L42. One line L41 is connected to the heat supply pipe 33 of the thermal decomposition furnace 3, and the other line L42 is connected to the inlet of the heat utilization apparatus 5. As shown in FIG. That is, the combustion exhaust gas discharged | emitted from the combustion furnace 4 is supplied to the heating jacket 32 of the thermal decomposition furnace 3 of the upstream through the line L4, and part of it is through the line L41, The other part is also supplied to the heat utilization apparatus 5 downstream by line L42.

In this embodiment, the combustion exhaust gas line is divided into two, and the combustion exhaust gas is distributed to the thermal decomposition furnace 3 and the heat utilization device 5. However, the combustion exhaust gas lines may be divided into three, and the combustion exhaust gas may be distributed to the dryer 2 as well as the thermal decomposition furnace 3 and the heat utilization device 5. Moreover, you may connect the combustion exhaust gas lines for each apparatus in series so that combustion exhaust gas may pass in order from an apparatus with high process temperature to an apparatus with low process temperature, without branching a combustion exhaust gas line. Alternatively, the combustion exhaust gas line may be connected only to the heat utilization apparatus 5.

The heat utilization device 5 has an inlet connected to the combustion exhaust gas line L42 and an outlet connected to the discharge line L5 for discharging the low temperature combustion exhaust gas. As the heat utilization apparatus 5, a waste heat boiler is used, for example. In the main body of the heat utilization apparatus 5, the internal flow path through which the fruit heat-exchanges with combustion exhaust gas flows is formed. The internal flow path of the heat utilization device 5 can be in various forms, such as an opposing flow path, a parallel flow path, or a serpentine shape flow path.

The discharge line L5 is branched into two lines L6 and L7. One line L6 is further connected to a downstream heat utilization apparatus (not shown) or is open to the air via a harmless device (not shown).

The other line L7 is a reflux line L71 for refluxing the low temperature combustion exhaust gas to the combustion furnace 4 and a reflux line L72 for refluxing the low temperature combustion exhaust gas to the heat utilization device 5. It is branched. The first reflux line L71 joins the combustion air on the inlet side of the combustion furnace 4 or communicates with a burner injection port of the combustion furnace 4. The second reflux line L72 joins the combustion exhaust gas line L42 on the inlet side of the heat utilization device 5 or goes in parallel with the combustion exhaust gas line L42 and uses heat together with the line L42. It joins in the internal flow path of the apparatus 5.

The operation of this embodiment will be described.

Organic waste is input into the dryer 2 from the waste input apparatus (not shown) via the line L1. The dryer 2 heats the injected organic waste to a temperature of 100 ° C to 300 ° C to evaporate the water contained in the organic waste, and the organic waste contains 30% or less of water and preferably 20% or less of dry organic waste. Shall be. This dry organic waste is supplied to the hollow shaft chamber 31 of the thermal cracking furnace 3 by the line L2. The pyrolysis furnace 3 is heated to a temperature of 300 ° C. or higher to decompose the organic components in the waste. As a result, the organic waste is decomposed into solid carbide and gaseous flammable pyrolysis gas. Carbide is discharged | emitted and collect | recovered to a collection container (not shown) via the discharge line L8. On the other hand, flammable pyrolysis gas is supplied to the burner of the combustion furnace 4 via the line L3, and is mixed with combustion air and combusts. Combustion air is supplied by a compressor (not shown), a blower, or the like. In addition, the combustion air may be a mixed gas in which the low temperature combustion exhaust gas from the heat utilization apparatus 5 is mixed with the air supplied from a compressor or a blower.

The combustion exhaust gas is discharged from the exhaust port 41 of the combustion furnace, and passes through the line L4. A part of the combustion exhaust gas passes through the line L41 and is introduced from the fruit supply pipe 33 into the heating jacket 32 of the pyrolysis furnace 3 to thermally decompose the organic waste in the hollow shaft chamber 31. It becomes a heat source. The other part of combustion exhaust gas passes through the line L42, is supplied to the internal flow path of the heat utilization apparatus 5, and is heat-exchanged with fruit.

As for the combustion exhaust gas supplied to the heat utilization apparatus 5, heat energy is collect | recovered by the heat utilization apparatus 5, and temperature falls to 500 degrees C or less. The combustion exhaust gas is discharged from the heat utilization device 5 via the discharge line L5 as the low temperature combustion exhaust gas. A part of this low temperature combustion exhaust gas flows through the reflux line 7 and the 1st reflux line L71 from a branch part, and is injected from the burner of the combustion furnace 4. In addition, the other part of the low temperature combustion exhaust gas flows from the branch through the reflux line 7, the second reflux line L72 and the line L42 and is mixed with the combustion exhaust gas to flow into the internal flow path of the heat utilization device 5. Is fed back to. Moreover, as a device which can be used as a heat utilization device of this embodiment, there is an air preheater (not shown), a pyrolysis furnace 3, a waste heat boiler (not shown), a dryer 2 and the like.

The effect of this embodiment is explained.

According to this embodiment, the low-temperature combustion exhaust gas after heat is used by the heat utilization device has a higher temperature than at least the outside air. Therefore, a part of the low temperature combustion exhaust gas is refluxed to the combustion furnace 4 using the reflux line L71 and used as a part of the combustion air by the burner of the combustion furnace 4, thereby making the outside air as combustion air. The combustion temperature of the combustion furnace 4 can be maintained with a small amount of pyrolysis gas compared with the case of using only bay. For this reason, the quantity of combustion exhaust gas, ie, the amount of low-temperature combustion exhaust gas, becomes small, and the quantity of heat discarded as waste can be significantly reduced, and thermal efficiency can be improved.

Moreover, an upper limit arises in the temperature of combustion exhaust gas for the reason of the material of the heat utilization apparatus 5, etc. When the low temperature combustion exhaust gas is combined with the combustion exhaust gas using the reflux line L72, and the low temperature combustion exhaust gas is used as the dilution air of the combustion exhaust gas, the temperature of the combustion exhaust gas can be lowered.

When the combustible gas obtained by thermal decomposition of organic waste is combusted, nitrous oxide (N ₂ O), which is a greenhouse gas, is released depending on the type of waste and the combustion situation. Figure 2 shows the result of examining the relationship between combustion temperature (℃) and combustion N ₂ O concentration (volume ppm) in the exhaust gas of the furnace.

As is apparent from FIG. 2, the N ₂ O concentration decreases as the combustion temperature of the combustion furnace increases, and greatly decreases at a combustion temperature of 900 ° C. or higher. In particular, the combustion temperature over the temperature range 950 ℃ N ₂ O concentration is hardly changed. In order to reduce the N ₂ O concentration, a high combustion temperature is required. In the present embodiment, since the low temperature combustion exhaust gas that is higher than the outside air is used as part of the combustion air, the combustion temperature can be maintained at a high temperature at a lower flow rate. Therefore, according to the embodiment, the N ₂ O concentration in the combustion exhaust gas discharged from the combustion furnace 4 can be made low.

(Second Embodiment)

A second embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

The waste disposal system 1A of this embodiment is further provided with the dust collector 10 on the line L42 which connects the combustion furnace 4 and the heat utilization equipment 5. As shown in FIG. The dust collector 10 is a cyclone which descends, for example, the combustion exhaust gas introduced into the upper portion as a swirl flow, and centrifugally separates the solid content in the combustion exhaust gas from the gaseous fraction. In addition, solid content in combustion exhaust gas is a dust etc. which contain non-combustible dust.

When dust of solid incombustibles is mixed in the pyrolysis gas, the solid incombustibles cannot be combusted in the combustion furnace 4, but are mixed as dust in the combustion exhaust gas. Sold out is an air pollutant. In addition, when the dust is attached to the inner flow path or the inner wall of the heat-use device, the attached dust decreases the thermal conductivity, thereby reducing the thermal efficiency of the heat-use device. However, according to the system of the present embodiment, since the dust collector separates and removes the dust from the combustion exhaust gas, it is possible to prevent a decrease in the thermal conductivity of the heat-use device. In addition, according to the system of the present embodiment, the emission of air pollutants into the atmosphere can also be reduced. The effect can be reduced to N ₂ O concentration in the combustion exhaust gas is discharged, it is the same as the first embodiment.

(Third Embodiment)

A third embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

The waste treatment system 1B of the present embodiment further includes an auxiliary fuel supply device 11. The auxiliary fuel supply device 11 has an injection line L9 connected to the pyrolysis gas line L3. The auxiliary fuel supply device 11 injects the auxiliary fuel into the pyrolysis gas flowing through the pyrolysis gas line L3, and causes the auxiliary fuel to be injected and injected from the burner of the combustion furnace 4. In addition, the injection line L9 does not necessarily need to be connected to the pyrolysis gas line L3, and may provide a burner separately to the combustion furnace 4, and may connect to it.

The combustion furnace 4 uses flammable pyrolysis gas as a heat source which maintains the temperature of the combustion furnace 4. When the amount of heat recovered by the heat utilizing device 5 increases, if the amount of heat generated by the pyrolysis gas is constant, the temperature of the low-temperature combustion exhaust gas may decrease, resulting in defects such as condensation. In order to increase the amount of heat recovered by the heat utilization device 5 while maintaining the temperature of the low temperature combustion exhaust gas, the heat amount of the pyrolysis gas may be increased. In this case, it is necessary to increase the throughput of the organic waste which is a raw material of the pyrolysis gas. However, there is a limit to the throughput of organic waste due to limitations in the specifications of the pyrolysis furnace.

Therefore, in the present embodiment, when the heat source is insufficient in the heat utilizing device, auxiliary fuel such as methane gas is injected from the auxiliary fuel supply device 11 as the fuel of the combustion furnace 4. Thereby, the lack of a heat source can be eliminated. In addition, this embodiment also has the advantage that the auxiliary fuel from the auxiliary fuel supply device 11 can be used as fuel at the start and stop of the waste treatment system in which organic waste is not added. The effect can be reduced to N ₂ O concentration in the combustion exhaust gas is discharged, it is the same as the first embodiment.

According to the waste treatment system of at least one embodiment described above, the waste treatment system which can suppress generation | occurrence | production of nitrous oxide can be provided.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their modifications fall within the scope and spirit of the invention and are included in the scope of equivalents of the invention described in the claims.

1: waste disposal system
2: dryer
3: pyrolysis furnace
4: combustion device
5: heat-using device
10: dust collector
11: auxiliary fuel supply
31: hollow shaft seal
32: heating jacket
33: fruit supply pipe
34: fruit discharge tube
41: outlet
43: burner

Claims (8)

A thermal decomposition furnace that receives an organic waste containing organic nitrogen and thermally decomposes the organic waste in a high-temperature reducing atmosphere,
A combustion furnace for combusting the flammable pyrolysis gas generated in the pyrolysis furnace at a temperature of 900 ° C or more and 1000 ° C or less so that generation of nitrous oxide (N ₂ O) is suppressed,
A heat utilization apparatus using combustion exhaust gas generated in the combustion furnace as a heat source;
The low-temperature combustion exhaust gas after the use of heat used by the heat utilization device and the temperature is lowered is refluxed from the heat use device to the device arranged upstream from the heat use device, so that combustion air is generated in the combustion furnace. Or a reflux line for use as dilution air in the heat utilization device. delete The method of claim 1,
And a dryer disposed more upstream than the thermal decomposition furnace, the dryer further reducing the moisture content of the organic waste by heating the organic waste to evaporate water from the organic waste. delete The method according to claim 1 or 3,
And a dust collector between the heat utilization device and the combustion furnace. The method according to claim 1 or 3,
And an auxiliary fuel supply device for supplying auxiliary fuel to the combustion furnace. The method of claim 1,
And a line for supplying the combustion exhaust gas discharged from the combustion furnace to the pyrolysis furnace. The method of claim 7, wherein
The pyrolysis furnace has a hollow shaft chamber to which organic waste is supplied and a heating jacket for heating the hollow shaft chamber, and the line for supplying the combustion exhaust gas to the pyrolysis furnace supplies the combustion exhaust gas. And a waste treatment system for supplying the heating jacket.

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