JP2011079890A - Multi-stage screw carbonization furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-stage screw carbonization furnace wherein the temperature in the furnace can be controlled to a prescribed temperature range. <P>SOLUTION: In the multi-stage screw carbonization furnace 1, a plurality of screw conveyors 2 that convey a carbonization target in a trough 11 by rotating a screw 12 are connected one above another, and the screw conveyor 2 at an upper stage is heated from below by combustion heat of a dry distillation gas generated from the carbonization target on the screw conveyor 2 at a lower stage. The furnace 1 comprises: an air supplying means 22 that supplies combustion air into the furnace; a thermometer 25 that detects temperature in the furnace; and a control means 26 that controls the air supplying means 22 and a driving means 16 of the screw 12 based on a value detected by the thermometer 25, wherein the control means 26 controls the air supplying means 22 so as to control supply of the combustion air to the dry distillation gas so that the temperature in the furnace reaches a prescribed temperature under an air ratio of ≤1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multi-stage screw carbonization apparatus that moves a carbonized furnace inside a multi-stage screw conveyor to carbonize the object to be carbonized, and more particularly to a multi-stage screw carbonization furnace that adjusts the furnace temperature within a set temperature range.

  Organic wastes such as livestock manure discharged from barns are considered to be made into carbides in order to make effective use thereof, and various carbide production apparatuses have been proposed in recent years. For example, FIG. 3 is a view showing a multistage screw carbonization furnace described in Patent Document 1 below. In this multistage screw carbonization furnace, three stages of screw conveyors 111, 112, and 113 are arranged vertically so as to cross the furnace body 102.

  Organic waste (carbonized material) supplied from the hopper 104 is sequentially sent from the uppermost screw conveyor 111 to the lower screw conveyors 112 and 113 by the rotation of the screw 122. During that time, the upper screw conveyors 111 and 112 are heated directly by the combustion heat of the dry distillation gas blown out from the gas blower outlet 135 together with the heating by the burner 108 at the lower part of the furnace, and the carbonized material inside the conveyor is heated and carbonized. To do.

JP 2001-172039 A

  In a multi-stage screw carbonization furnace, a cylindrical trough constituting a screw conveyor is made of stainless steel or the like, and the furnace temperature needs to be 900 ° C. or less in order to prevent deformation and corrosion due to heat. However, it is difficult to control the furnace temperature, and until now, no particularly strict control has been performed. With respect to the rise in the furnace temperature, the generation of dry distillation gas can be reduced by reducing the supply amount of the object to be carbide, and the temperature rise can be adjusted.

  In addition, when the temperature is adjusted according to the supply amount of the carbide, it is necessary to increase the supply amount of the carbide to raise the furnace temperature when the temperature is extremely lowered. Even in such a case, the followability is poor and the temperature does not recover suddenly, so the burner installed at the bottom of the furnace is fully operated. Heating with increased output of the burner 108 not only increases fuel consumption and does not allow stable operation, but also may not allow sufficient carbonization. Therefore, it is difficult to control the temperature appropriately even if the amount of feed is controlled.

  In view of the above, an object of the present invention is to provide a multi-stage screw carbonization furnace that controls the furnace temperature within a set temperature range.

The multi-stage screw carbonization furnace of the present invention is configured such that a plurality of screw conveyors that convey the carbonized material in the trough are connected up and down by rotating screws, and the upper screw is generated by the combustion heat of dry distillation gas generated from the carbonized material of the lower screw conveyor. The conveyor is heated from below, an air supply means for supplying combustion air into the furnace, a thermometer for detecting the temperature in the furnace, the air supply means based on the detected value of the thermometer, and the Control means for controlling the drive means of the screw, and the control means supplies the combustion air to the dry distillation gas so that the furnace temperature becomes a predetermined temperature in the region where the air ratio is 1 or less. It is characterized by controlling the above.
Further, in the multi-stage screw carbonization furnace of the present invention, the air supply means feeds the outside air into the furnace by a blower, and the amount of the outside air is determined by the opening degree of the flow path by the automatic damper provided in the outside air supply pipe. It is preferable to perform automatic adjustment.

  According to the present invention, the inside of the furnace is controlled to an appropriate temperature and heated by automatically adjusting the supply amount of the combustion air, the conveying speed of the carbonized material, and the inflow amount of the combustion air to the dry distillation gas according to the set temperature in the furnace. The trough can be prevented from thermal deformation and corrosion without passing too much. At that time, since the air ratio of the combustion air to the dry distillation gas is set to 1 or less, the amount of generated gas can be reduced, and the volume of the combustion chamber of the furnace body can be reduced. As a result, the multistage screw carbonization furnace Can be reduced in size.

It is the conceptual diagram which showed one Embodiment of the multistage screw carbonization furnace. It is the figure which made the result of having calculated exhaust gas temperature with respect to air ratio, oxygen concentration, the amount of exhaust gas, and the amount of combustion graphed. It is the figure which showed the conventional multistage screw carbonization furnace.

Next, an embodiment of a multi-stage screw carbonization furnace according to the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing an embodiment of a multi-stage screw carbonization furnace.
In the multi-stage screw carbonization furnace 1, similarly to the above-described conventional example, the carbide to be introduced from the hopper 8 passes through the screw conveyor 2 provided in four stages in the vertical direction, and is heated and pyrolyzed to thereby remove the carbide. It is a device to generate.

  In the screw conveyor 2, a cylindrical trough 11 is installed so as to pass through opposite wall surfaces of the furnace body 3, and a screw 12 that is rotated by a motor 16 that is driving means is inserted into the trough 11. The to-be-carburized material in the trough 11 is sent while being agitated by the rotation of the screw 12, and moves to the lower stage by a chute 13 that connects the upper and lower troughs 11. In the multistage screw carbonization furnace 1, a heating chamber 4 is provided in the lower part of the furnace body 3, and the screw conveyor 2 in the furnace is heated by the flame of the burner 5.

  The carbide to be carbonized in the screw conveyor 2 is carbonized by heating while being conveyed. In the process, combustible dry distillation gas is generated from the carbonized material. A plurality of air outlets 15 are formed on the upper surface of the trough 11, and the screw conveyor 2 located in the upper stage is heated by a flame of dry distillation gas blown upward therefrom. That is, in the multistage screw carbonization furnace 1, the screw conveyor 2 of each stage is heated by the flame from the lower screw conveyor 2 in addition to the heating by the flame injected from the burner 5.

In the present embodiment, a temperature control system is formed so that an excessive temperature rise does not occur with respect to the heating in the furnace. In particular, the temperature control system adjusts the temperature by controlling the conveying speed of the object to be carbonized and the combustion air with respect to the dry distillation gas.
The multi-stage screw carbonization furnace 1 is provided with an outside air supply pipe 21 for feeding combustion air. The outside air supply pipe 21 is formed on the side wall of the furnace body 3 and the heating chamber 4 with respect to the screw conveyor 2 and the burner 5 at each stage. Each outdoor air supply pipe 21 is provided with an automatic damper 22 so that the supply amount of the external air (combustion air) supplied to the furnace body 3 and the heating chamber 4 is automatically adjusted according to the opening degree of the flow path of the external air supply pipe 21. It is configured.

  On the other hand, the carbonization furnace 1 is provided with a thermometer 25 for measuring the temperature of the upper portion of the furnace body 3 and a temperature adjustment controller 26 for controlling the automatic damper 22 based on the detected value of the temperature in the furnace. . Outside air is sent into the furnace by a blower (not shown), and the automatic damper 22 can adjust the supply amount of outside air based on a control signal from the temperature adjustment controller 26. The multistage screw carbonization furnace 1 controls the heating by the combustion heat of the dry distillation gas by adjusting the supply amount of the outside air and the conveyance amount of the carbonized material sent by the screw conveyor 2.

  The to-be-carburized material, which is an organic waste such as chicken manure, varies in its state when it is supplied to the multistage screw carbonization furnace 1. This is because the livestock excrement may be left for several days, weeks or months before being processed in the multistage screw carbonization furnace 1, and the amount of dry distillation gas varies depending on the difference in the storage period. If the standing period is long, the organic matter is fermented, the amount of the organic matter is reduced at the time of carbonization, and the amount of dry distillation gas generated by heating is also reduced. Therefore, even if a certain amount of carbide is supplied to the multi-stage screw carbonization furnace 1, the amount of dry distillation gas changes, and the heating temperature in the furnace becomes unstable.

  Therefore, in this embodiment, the motor 16 is connected to the temperature adjustment controller 26, and the number of rotations of the motor 16 is switched by control based on a temperature change. That is, the amount of dry distillation gas generated is made constant by changing the conveying speed of the screw 12 and adjusting the residence time of the object to be carbide in the furnace. The multistage screw carbonization furnace 1 is provided with a plurality of motors 16 and automatic dampers 22, which are independently controlled by a temperature adjustment controller 26.

  The multi-stage screw carbonization furnace 1 needs to be temperature-controlled to 900 ° C. or less in order to protect the apparatus. For example, as a method of controlling the furnace temperature to 800 ° C., there is a method of setting the air ratio of combustion air to 1 or more. If the air ratio of the combustion air to the dry distillation gas is 1, all of the supplied combustion air is combusted. If the air ratio is 1 or more, the excess air that is not used for combustion is used to cool the furnace. used. Therefore, conventionally, when the temperature in the furnace rises, control is performed so as to lower the temperature by supplying cooling air so that the air ratio becomes 1 or more.

  However, if the air ratio is set to 1 or more, excessive heating can be prevented due to the cooling effect, but a large volume of air must be put into the furnace to increase the processing volume, and the furnace body 3 becomes larger accordingly. There was a problem to do. In addition, if the amount of air is large, the amount of exhaust gas increases, and the amount of fuel necessary for the treatment in the secondary combustion chamber of the carbonization furnace increases, increasing the fuel cost.

Therefore, in this embodiment, the amount of combustion air supplied into the furnace is controlled so that the air ratio becomes 1 or less. FIG. 2 is a graph showing the results of calculating exhaust gas temperature (° C.), oxygen concentration (%), exhaust gas amount (Nm ³ / h), and combustion amount (kg / h) with respect to the air ratio. It is a theoretical value that does not include etc. As shown in this result, the exhaust gas temperature, the oxygen concentration, the exhaust gas amount, and the combustion amount greatly changed at a value of about 0.95 (point C) near the air ratio 1. The exhaust gas temperature is used for combustion of the dry distillation gas until the air ratio becomes 1, and the temperature is raised. However, the temperature of the excess air is reduced because the excess air cools the inside of the furnace body 3.

At this time, the air ratio at which the thermometer 25 measures the set temperature of 800 ° C. was about 0.7 (A part) and about 2.7 (B part). When the air ratio is 0.7, since the amount of air necessary for combustion of the generated dry distillation gas is small, only the amount of supplied dry distillation gas is combusted in the furnace body 3 and the calorific value is suppressed. It is. Further, in the conventional method for increasing the air ratio to 2.7, almost all of the dry distillation gas is combusted and heated by the generated heat, while surplus air is used for cooling in the furnace and the temperature is lowered. .

  The generation of dry distillation gas does not change with the increase or decrease in the amount of combustion air. Therefore, the combustion amount of the dry distillation gas generated by adjusting the combustion air amount can be manipulated, and the heating temperature in the furnace can be adjusted by adjusting the combustion amount. In the multistage screw carbonization furnace 1, the temperature adjustment controller 26 controls the automatic damper 22 based on the temperature detected by the thermometer 25, and a predetermined amount of outside air is supplied into the furnace body 3 as combustion air via the outside air supply pipe 21. Is done. At that time, the supply amount of the combustion air is adjusted so that the air ratio of the combustion air is 1 or less and the heating temperature in the furnace is about 800 ° C. In this embodiment, the air ratio of combustion air is approximately 0.7.

  When the air ratio of the combustion air is set to 0.7 which is 1 or less in this way, the combustion amount of the dry distillation gas is reduced as shown in FIG. Therefore, the feed rate of the object to be carbonized by the screw 12 is adjusted so that the heating with the dry distillation gas is sufficiently performed. Specifically, as described above, the temperature adjustment controller 26 controls the driving of the motor 16 based on the temperature detected by the thermometer 25. The conveying speed of the to-be-carburized substance is lowered to increase the residence time, and the amount of dry distillation gas generated in the furnace body 3 is made constant to stabilize the heating temperature. Moreover, the recovery rate of the carbide | carbonized_material obtained by passing through the multistage screw carbonization furnace 1 can also be stabilized by this.

By the way, when the air ratio is set to 1 or more, a large amount of air is sent and almost all of the dry distillation gas is combusted. Therefore, the furnace body 3 needs a size for that purpose. As shown in FIG. 2, when the air ratio is 2.7, both the oxygen concentration and the amount of exhaust gas are large, and the oxygen concentration is about 0.5% in the portion A near the air ratio 0.7, whereas the air ratio 2 It was 13.5% in B part near 0.7. Exhaust gas amount, whereas the A section is about 600 Nm ³ / h, in the B portion also became about 4300Nm ³ / h. Therefore, the conventional carbonization furnace requires such a large volume. However, the furnace body 3 of this embodiment should just consider arrangement | positioning of the screw conveyor 2, and even if it is a narrow space, it functions sufficiently and it can be set as the structure which reduced the furnace body 3. FIG.

  Therefore, in the multi-stage screw carbonization furnace 1 as described above, the material to be carbonized introduced from the hopper 8 is put into the upper screw conveyor 2, moved horizontally while being stirred by the screw 12 rotating in the trough 11, 13 is sequentially conveyed to the screw conveyor 2 to the lower stage via 13. Meanwhile, the screw conveyor 2 is heated by the combustion heat generated by the burner 5 in the heating chamber 4 and is also heated by the combustion heat of the dry distillation gas blown out from the lower screw conveyor 2 located immediately below.

  Further, the temperature inside the furnace is detected by the thermometer 25. According to the detected temperature, the motor 16 and the automatic damper 22 are controlled by the temperature adjusting controller 26, and the conveyance speed of the carbonized material and the amount of combustion air are adjusted. In this embodiment, since the air ratio is 1 or less, when the temperature rises with respect to the set temperature, the amount of combustion air supplied by the automatic damper 22 is reduced, and the amount of combustion of dry distillation gas is reduced, thereby suppressing the heating temperature. It is done. On the other hand, in the case of a carbide to be generated with a small amount of dry distillation gas, the combustion amount does not increase and the temperature may not rise. In such a case, the combustion amount of the burner 5 is increased or the conveyance speed of the carbide is increased. The temperature can be controlled by lowering and increasing the residence time.

  In the temperature adjustment controller 26, the dry distillation gas is burned with an air ratio of 1 or less in order to suppress the temperature rise, so that the dry distillation gas that could not be burned remains in the furnace. However, the carbonized gas after combustion is sent from the furnace body 3 to a secondary combustion chamber (not shown), where it is burned as an auxiliary combustion component for maintaining the temperature. The dry distillation gas generated from the carbonized substance and the exhaust gas after combustion are completely combusted in the secondary combustion chamber to be made pollution-free, and are released into the atmosphere through a bag filter or the like.

  In the carbide manufacturing method as described above, for example, when 700 kg / h of a carbonized material is fed into the multi-stage screw carbonization furnace 1 and the dry distillation gas is burned with combustion intake air having an air ratio of 0.7, the dry distillation gas is about 100 kg / h. It burns and approximately 350 kg / h of carbide is obtained. In the secondary combustion chamber, combustion air having an air ratio of 2 is supplied, and complete combustion of the 250 kg / h dry distillation gas remaining by heating of the burner is performed.

  According to such a multistage screw carbonization furnace 1 of this embodiment, temperature adjustment in the carbonization furnace during carbonization is performed, and a certain amount of carbide is obtained. The furnace temperature fluctuates in a range of approximately 750 ° C. to 850 ° C. with a set temperature of 800 ° C., and thermal deformation and corrosion of the trough 11 are prevented without being overheated. At that time, since the temperature adjustment is performed by combustion control with an air ratio of 1 or less, the multistage screw carbonization furnace 1 can be downsized by reducing the volume of the furnace body 3.

As mentioned above, although one Embodiment of the multistage screw carbonization furnace concerning this invention was described, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
For example, in the above-described embodiment, the value of 0.7 is shown as the air ratio of the combustion air.

DESCRIPTION OF SYMBOLS 1 Multi-stage screw carbonization furnace 2 Screw conveyor 3 Furnace body 4 Heating chamber 11 Trough 12 Screw 16 Motor 21 Outside air supply pipe 22 Automatic damper 25 Thermometer 26 Temperature control controller

Claims (2)

Multi-stage screw carbonization that connects a plurality of screw conveyors that transport the carbide in the trough up and down with rotating screws, and heats the upper screw conveyor from below by the combustion heat of dry distillation gas generated from the carbide of the lower screw conveyor In the furnace,
An air supply means for supplying combustion air into the furnace, a thermometer for detecting the temperature in the furnace, and a control means for controlling the air supply means and the screw drive means based on the detected value of the thermometer. And the control means controls the supply of combustion air to the dry distillation gas so as to control the air supply means so that the furnace temperature becomes a predetermined temperature in the region where the air ratio is 1 or less. A featured multistage screw carbonization furnace. In the multi-stage screw carbonization furnace according to claim 1,
The air supply means is configured to send outside air into the furnace by a blower, and to automatically adjust the amount of outside air to be supplied according to the opening degree of the flow path by an automatic damper provided in the outside air supply pipe. A featured multistage screw carbonization furnace.

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