JP4033878B2 - Exhaust gas treatment method - Google Patents

Description

The present invention relates to a method for treating exhaust gas , and more particularly, introduces exhaust gas generated by burning waste in a primary combustion furnace so as to generate a swirl flow in the secondary combustion furnace, and the primary combustion furnace and The present invention relates to a method for treating exhaust gas in which exhaust gas generated by burning waste in a third combustion furnace different from the secondary combustion furnace is introduced by a hot air fan so as to generate a swirling flow in the secondary combustion furnace.

  Wastes such as municipal waste and industrial waste are generally burned in a combustion apparatus. As such an incinerator, there exists an incinerator shown by Unexamined-Japanese-Patent No. 7-229610 (patent document 1), for example. The combustion apparatus includes a primary combustion furnace having a burner, a cylindrical secondary combustion furnace, and an exhaust gas introduction path for introducing exhaust gas from the primary combustion furnace to the secondary combustion furnace. The exhaust gas is introduced in the tangential direction of the cylindrical surface of the cylindrical secondary combustion furnace so that a swirling flow is generated in the secondary combustion furnace.

  Moreover, in the combustion apparatus of patent document 1, the supply air supplied to a secondary combustion furnace is also introduce | transduced so that a swirl flow may arise in a secondary combustion furnace, a swirl flow is generated in a secondary combustion furnace, and combustion efficiency The mixing / stirring for the purpose of facilitating the heating and the securing of the residence time are performed.

  However, in the combustion apparatus configured as described above, air is supplied to the secondary combustion furnace into which the exhaust gas is introduced. Usually, the supply air is outside air, and its temperature is about 0 to 20 ° C., and the exhaust gas introduced from the primary combustion furnace into the secondary combustion furnace is remarkably cooled by this supply air. Therefore, in order to prevent a temperature drop in the secondary combustion furnace due to the supply air and to maintain the secondary combustion furnace at 800 to 1200 ° C., it is necessary to heat the supply air with a burner. Normally, recycled oil is used as the fuel for such a burner. However, since the amount of fuel used is enormous, it has been desired to reduce the amount of fuel used.

Therefore, the inventors of the present invention reduce the amount of fuel used for heating the supply air in a secondary combustion furnace that uses a swirling flow to treat the exhaust gas from the primary combustion furnace, and efficiently exhaust the exhaust gas. In order to provide an exhaust gas treatment method capable of treating and increasing the processing capacity, waste is combusted in a primary combustion furnace, and the exhaust gas from the primary combustion furnace is swirled in the secondary combustion furnace. In the method for treating exhaust gas to be treated, exhaust gas generated by burning waste in a third combustion furnace different from the primary and secondary combustion furnaces is supplied to the secondary combustion furnace as a heat source for the secondary combustion furnace. In addition, an exhaust gas treatment method characterized by turning into a swirling flow in a secondary combustion furnace was invented and a patent application was filed (Japanese Patent Application No. 2004-289103 (Patent Document 2)).
Japanese Patent Laid-Open No. 7-229610 Japanese Patent Application No. 2004-289103

According to the exhaust gas treatment method disclosed in Patent Document 2, it was recognized that the expected effect was achieved with regard to reducing the amount of fuel used. However, in the exhaust gas treatment method disclosed in Patent Document 2, the exhaust gas from the third combustion furnace is sucked by the hot air fan and is configured to be a swirling flow of the secondary combustion furnace. There are cases where the stable operation of the hot air fan is hindered due to the overload stop of the hot air fan due to the temperature change of the exhaust gas introduced from the third combustion furnace or the vibration of the hot air fan due to the rapid temperature rise of the exhaust gas. It was.

  In detail, when the temperature of the exhaust gas introduced from the third combustion furnace is lowered, the specific gravity of the exhaust gas is increased, which causes an overload stop of the hot air fan. On the other hand, when the temperature of the exhaust gas becomes high, vibration occurs due to the thermal expansion of the impeller of the hot air fan. When the vibration value exceeds the reference value, it is necessary to stop the operation to protect the hot air fan. However, the vibration value increases whenever the temperature of the exhaust gas from the third combustion furnace rises, so the operation is stopped. There was a problem that the frequency increased.

Accordingly, the present invention is stable in the third exhaust hot air fan to effectively prevent vibration occurrence of hot air fans due to the rapid temperature rise of the overload stop and the exhaust hot air fan due to temperature changes that occur from the combustion furnace It is an object of the present invention to provide a method for treating exhaust gas that can be continuously operated.

In order to solve the above-mentioned problem, the present invention described in claim 1 introduces exhaust gas generated by burning waste in a primary combustion furnace so as to generate a swirl flow in the secondary combustion furnace. In an exhaust gas treatment method, exhaust gas generated by burning waste in a third combustion furnace different from the combustion furnace and the secondary combustion furnace is introduced by a hot air fan so as to generate a swirling flow in the secondary combustion furnace. The temperature detection means detects the temperature of the exhaust gas generated in the third combustion furnace supplied to the hot air fan, and adjusts the intake amount of the exhaust gas by controlling the opening of the motor-operated valve based on the temperature , operation whereby the hot air fan stable by controlling the hot air fan operating current so as not set value or more current flows in advance for the hot air fan Characterized by being realized.

In order to solve the above-mentioned problem, the present invention according to claim 2 is the exhaust gas processing method according to claim 1, wherein the intake air amount of the hot air fan is set so that the hot air fan operating current becomes a predetermined value equal to or less than a rated value. It is characterized by adjusting.

  In order to solve the above-mentioned problem, the present invention according to claim 3 is the exhaust gas treatment method according to claim 1 or 2, wherein the temperature of the exhaust gas generated in the third combustion furnace supplied to the hot air fan is increased. In this case, the intake air amount of the exhaust gas is adjusted, and outside air is introduced to prevent a rapid increase in the inlet temperature of the hot air fan.

  In order to solve the above-mentioned problem, the present invention described in claim 4 is characterized in that in the exhaust gas treatment method described in claim 3, the increase in the inlet temperature of the hot air fan is 10 ° C./min or less.

  In order to solve the above-mentioned problem, the present invention according to claim 5 is the exhaust gas processing method according to claim 3 or 4, wherein the control of the intake amount of exhaust gas and / or introduction of outside air is performed by controlling the opening of the motor-operated valve. It is performed by controlling.

According to the exhaust gas treatment method of the present invention, the hot air fan can be continuously operated, and the amount of fuel used in the secondary combustion furnace can be further reduced.
In addition, according to the exhaust gas processing method of the present invention, when exhaust gases other than the third combustion furnace are processed simultaneously, the amount of exhaust gas can be reduced, so that it is possible to increase the processing of the primary combustion furnace of the main body. There is.

  The exhaust gas treatment method according to the present invention will be described in detail below with reference to the drawings. Initially, the whole structure in one Embodiment of the incineration processing system for implementing the processing method of the waste gas concerning this invention is shown. FIG. 1 is a configuration diagram of the incineration processing system.

  The incineration processing system 100 shown in FIG. 1 schematically includes a primary combustion furnace 1 such as a rotary kiln constituting a primary combustion chamber that combusts waste, and a secondary combustion chamber that processes exhaust gas G1 from the primary combustion furnace 1. The secondary combustion furnace 2 is configured, and the primary combustion furnace 1 and the third combustion furnace 3 different from the secondary combustion furnace 2 are provided.

  The third combustion furnace 3 is a stationary furnace for incinerating precious metal scrap raw materials and industrial waste including, for example, electronic boards such as personal computers and mobile phones. The precious metal scrap raw material and waste to be incinerated in the third combustion furnace 3 preferably contain unburned components such as carbon oxide and hydrocarbons in the exhaust gas. Such a combustion treatment furnace generates exhaust gas G3 having a maximum of about 700 ° C. containing unburned components.

  In the incineration processing system 100, the exhaust gas G1 generated in the primary combustion furnace 1 is introduced into the secondary combustion furnace 2 via the line L1 in order to completely burn it. On the other hand, the exhaust gas G3 from the third combustion furnace 3 passes through lines L2, L4, L5, L7, L8, and L9 through a path supplied as a swirling flow into the secondary combustion furnace 2 via the lines L2 and L1. Through the secondary combustion furnace 2. That is, an electric valve 23 for opening and closing the path is provided between the line L1 and the line L3, and the exhaust gas G1 from the primary combustion furnace 1 and the exhaust gas G3 from the third combustion furnace 3 are mixed. Then, it can be supplied to the secondary combustion furnace 2 by the line L1. The motor-operated valve 23 is closed in principle during normal operation, and the path supplied to the secondary combustion furnace 2 via the lines L2, L4, L5, L7, L8, and L9 is the main path. .

  The exhaust gas G3 from the third combustion furnace 3 is introduced into a cyclone (not shown) via lines L2 and L4 so that dust in the exhaust gas G3 is removed, and the exhaust gas G3 from which dust has been removed is It is introduced into the hot air fan 14 via the lines L5, L7, L8, and is supplied to the secondary combustion furnace 2 by the hot air fan 14 via the line L9. Here, the hot-air fan 14 gives the pressure for turning to the exhaust gas G3. An electric valve 21 for opening and closing the path is provided between the line L4 and the line L5, and an electric valve 24 for opening and closing the path is also provided between the line L7 and the line L8. Is provided.

Further, a temperature detection means 18 is provided in a line L8 between the electric valve 24 and the hot air fan 14. A control means 30 is disposed between the temperature detection means 18 and the hot air fan 14 and adjusts the intake air amount of the hot air fan 14 based on the temperature of the exhaust gas G3 measured by the temperature detection means 18. The hot air fan operating current is controlled. As a result, the hot air fan 14 can be stably operated.

  This point will be described in detail. Conventionally, when the temperature of the exhaust gas G3 of the third combustion furnace 3 is lowered, the specific gravity of the exhaust gas G3 is increased, so that the overload stop of the hot air fan 14 has occurred. Therefore, a predetermined value less than the rated value is set for the hot air fan operating current in advance, and the suction amount is adjusted by controlling the opening degree of the motor-operated valve 24, so that the current greater than the set value for the hot air fan 14. The hot air fan operating current is controlled so as not to flow. As a result, the intake air amount of the hot air fan 14 is limited, and the overload stop is effectively prevented. In this regard, in the exhaust gas treatment method disclosed in Patent Document 2, the intake valve amount is controlled by simply opening and closing the motor-operated valve based on the temperature of the exhaust gas without considering the operating state of the hot air fan. On the other hand, the method of the present invention is greatly different in that the supply amount of the exhaust gas G3 is controlled by paying attention to the operating state of the hot air fan 14.

  On the other hand, the line L5 is provided with a line L6 for taking in the outside air A1 through the electric valve 22. When the temperature detection means 18 detects the temperature rise of the exhaust gas G3 from the third combustion furnace supplied to the hot air fan 14, the information is sent to the control means 30, and the control means 30 opens the opening of the motor-operated valves 21 and 22. Control. As a result, the intake air amount of the exhaust gas G3 is adjusted, and the motor-operated valve 22 is opened to introduce outside air to prevent a rapid increase in the inlet temperature of the hot air fan 14. When the opening degree of the motor-operated valve 21 is limited and the flow rate of the exhaust gas flowing through the line L4 is limited, the excess exhaust gas G3 is controlled from the line L3 to the line L1 by controlling the opening degree of the motor-operated valve 23. And can be supplied to the secondary combustion furnace 2.

  This point will be described in detail. Conventionally, when the temperature of the exhaust gas G3 becomes high, vibration has occurred due to the thermal expansion of the impeller of the hot air fan 14. When the vibration value exceeds the reference value, it is necessary to stop the operation to protect the hot air fan 14, but the vibration value always increases as the temperature of the exhaust gas G3 from the third combustion furnace 3 rises. So I had to stop driving. Therefore, when the temperature of the exhaust gas G3 measured by the temperature detection means 18 rises, the control means 30 controls the opening degree of the motor-operated valve 21, thereby adjusting the intake amount of the exhaust gas G3 and opening the motor-operated valve 22. By controlling the degree, outside air (cold air) is introduced to control the temperature of the hot air fan 14 so as to prevent a rapid increase in the inlet temperature. Conventionally, since the increase in the inlet temperature of the hot air fan 14 has not been controlled, the inlet temperature may increase at 50 to 100 ° C./min. In this regard, it is preferable to suppress the increase in the inlet temperature of the hot air fan 14 to 10 ° C./min or less. This is because if the temperature rises to such a level, the impeller of the hot air fan does not expand rapidly, and the hot air fan 14 can be stably operated without the vibration value exceeding the reference value.

  As described above, the exhaust gas G1 from the primary combustion furnace 1 is introduced into the secondary combustion furnace 2 via the line L1, and the exhaust gas G3 from the third combustion furnace 3 is connected to the lines L2, L4, L5. , L8 and L9, are introduced into the secondary combustion furnace 2.

  Next, with reference to FIG.2 and FIG.3, schematic structure of the secondary combustion furnace 2 in this embodiment is demonstrated. The illustrated secondary combustion furnace 2 has a cylindrical shape inside, and the exhaust gas G1 (in some cases, a mixed gas of the exhaust gas 1 and the exhaust gas G3) is introduced into the secondary combustion furnace 2 via the line L1, Further, the exhaust gas G3 is introduced into the secondary combustion furnace 2 through lines L2, L4, L5, L7, L8, and L9.

  Further, a burner 40 is disposed in the secondary combustion furnace 2, and fuel such as regenerated oil is supplied as necessary. In the present embodiment, two burners 40 are provided so as to face each other in the diametrical direction, but not toward the furnace center. However, the present invention is not limited to this.

  Further, a combustion fan (not shown) is disposed adjacent to the secondary combustion furnace 2. The combustion fan (not shown) supplies air A4 to the burner 40 and is used for combustion of the regenerated oil injected by the burner 40.

  The secondary combustion furnace 2 is formed with a ring header 50 having an annular space. A line L9 is connected to the outer periphery of the ring header 50, and the exhaust gas G3 from the third combustion furnace 3 is introduced into the ring header 50. Further, a plurality of introduction holes formed in the secondary combustion furnace 2, that is, six introduction holes 55 in the present embodiment are opened in the inner peripheral portion of the ring header 50. The number and arrangement of the introduction holes 55 are not limited to this. For example, six introduction holes 55 may be formed in two upper and lower stages.

  In addition, the introduction hole 55 is formed so as not to go to the center of the secondary combustion furnace 2, and therefore, the exhaust gas G 3 introduced into the ring header 50 passes through the introduction hole 55. It is injected into the inside as a swirl flow.

  The shape, size, arrangement, etc. of the lines L1, L9, the burner 40, the air introduction hole 55, etc. with respect to the secondary combustion furnace 2 are not limited to the illustrated embodiment, and an appropriate shape, size, It can be arranged.

  According to the combustion processing system 100 including the secondary combustion furnace 2 having the above-described configuration, the waste introduced into the primary combustion furnace 1 is burned to generate exhaust gas G1 at 700 to 1000 ° C., and the inside of the secondary combustion furnace 2 It is introduced in the tangential direction of and becomes a swirling flow. Further, an exhaust gas G3 of 50 to 1000 ° C. is generated from the third combustion furnace 3 and is introduced from the introduction hole 55 of the ring header 50 through the hot air fan 14 to generate a swirling flow in the secondary combustion furnace 2. . Further, the combustion flame from the burner 40 also generates a swirling flow in the secondary combustion furnace 2.

  By the way, a temperature detection means (not shown) is arranged in the discharge line L10 from the secondary combustion furnace 2, and the temperature of the exhaust gas G5 is maintained from about 850 ° C. to the secondary combustion furnace 2 from the third incinerator 3. The amount of exhaust gas G3 supplied to the exhaust gas, that is, the amount of exhaust gas G3 generated from the third incinerator 3, the amount of exhaust gas G3 mixed into the line L1, or the amount of exhaust gas G3 supplied from the hot air fan 14 is adjusted. be able to. Further, if necessary, the operation mode of the burner 40 can be changed by adjusting the amount of fuel (regenerated oil) supplied to the burner 40 into which the supply air A4 is introduced. The exhaust gas G5 from the secondary combustion furnace 2 is introduced into a gas processing facility (not shown) via a line L10. The gas treatment equipment includes a quenching tower, a washing tower, a dust collector, a flue gas desulfurization tower, and the like, and the exhaust gas G5 is rapidly cooled, washed, dust-removed, desulfurized and released to the atmosphere.

According to the present embodiment having the above-described configuration, the hot air fan 14 is not stopped due to an overload of the current value, and the continuous operation of the hot air fan 14 can be performed stably. As a result, the amount of fuel used in the secondary combustion furnace 2 could be further reduced compared to the conventional case.
Moreover, the thermal expansion due to the rapid temperature rise of the impeller of the hot air fan can be suppressed, and the operation trouble due to the vibration value increase can be prevented.
Furthermore, when the exhaust gas other than the third combustion furnace 3 is processed simultaneously, the amount of exhaust gas can be reduced, so that the main combustion furnace can be increased. As a result, the processing cost can be greatly reduced.

1 is an overall configuration diagram of a waste treatment apparatus for carrying out an exhaust gas treatment method according to the present invention. It is a perspective view which shows the whole secondary combustion furnace structure. It is a cross-sectional view of a secondary combustion furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary combustion furnace 2 Secondary combustion furnace 3 3rd combustion furnace 14 Hot-air fan 18 Temperature detection means 21, 22, 23, 24 Electric valve 30 Control means 100 Incineration processing system

Claims (5)

In the third combustion furnace, the exhaust gas generated by burning the waste in the primary combustion furnace is introduced into the secondary combustion furnace so as to generate a swirl flow, and the third combustion furnace is different from the primary combustion furnace and the secondary combustion furnace. In the exhaust gas treatment method, the exhaust gas generated by burning waste is introduced so as to generate a swirling flow in the secondary combustion furnace by a hot air fan.
The temperature of the exhaust gas generated in the third combustion furnace supplied to the hot air fan is detected by temperature detection means , and the intake air amount of the exhaust gas is adjusted by controlling the opening of the motor-operated valve based on the temperature. conducted, whereby the processing of the exhaust gas, characterized in that which enables stable operation of the hot air fan by controlling the hot air fan driving current so does not flow preset value or more current to the hot air fan Method. The exhaust gas treatment method according to claim 1,
An exhaust gas treatment method comprising adjusting an intake amount of the hot air fan so that the hot air fan operating current becomes a predetermined value equal to or lower than a rated value. In the processing method of the exhaust gas of Claim 1 or 2,
When the temperature of the exhaust gas generated in the third combustion furnace supplied to the hot air fan rises, the intake air amount of the exhaust gas is adjusted and the outside air is introduced to rapidly increase the inlet temperature of the hot air fan. An exhaust gas treatment method characterized by preventing the rise. In the processing method of the exhaust gas according to claim 3,
A method for treating exhaust gas, characterized in that an increase in inlet temperature of the hot air fan is 10 ° C./min or less. In the processing method of the exhaust gas according to claim 3 or 4,
The exhaust gas treatment method, wherein the control of the intake amount of exhaust gas and / or the introduction of outside air is performed by controlling the opening of a motor-operated valve.

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