JP3853559B2 - Corrosion prevention method for exhaust gas treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing corrosion of an exhaust gas treatment device, and more particularly, an exhaust gas treatment device such as a denitration device or a dioxin removal device installed in a waste incinerator, particularly an exhaust gas bypass duct and a hot air circulation duct attached to the device. The present invention relates to a method suitable for preventing corrosion.
[0002]
[Prior art]
Nitrogen oxides (NOx) and dioxins (DNX) discharged from waste incinerators have become a particularly serious problem in recent years, and their emission standards have been set. Therefore, incineration facilities are equipped with denitration equipment and dioxin removal equipment to remove them. It has come to be. These devices are installed downstream of the dust collector from the viewpoint of dioxin resynthesis and gas composition in the exhaust gas.
The exhaust gas from the waste incinerator contains high concentrations of hydrogen chloride (HCl) and sulfur oxide (SOx). However, there are cases where the above components pass through the dust collector and become dust and flow into the exhaust gas treatment device such as a denitration device or a dioxin removal device.
[0003]
This dust is very hygroscopic and contains substances that degrade the catalyst and substances that are highly corrosive to steel, so if these dust adhere to the catalyst or the reaction tower that holds the catalyst, When the operation is stopped, the dust adhering to the catalyst absorbs moisture and causes the catalyst to be moistened, which causes deterioration of the catalyst and corrosion of the reaction tower. For this reason, when the incinerator is stopped, warm air is generated by a warm air generator using an electric heater as a heat source, and this warm air is circulated in the reaction tower by a hot air circulation duct to maintain the heat insulation state, and moisture is A method to prevent it from being taken is adopted.
[0004]
FIG. 5 is a conventional operation explanatory diagram at the time of steady operation of an incinerator in an exhaust gas treatment apparatus provided with a hot air circulation duct and an exhaust gas bypass duct.
In FIG. 5, the exhaust gas discharged from an incinerator (not shown) is supplied to the exhaust gas treatment device 1 via the inlet exhaust gas duct 4A, processed, and then discharged from the outlet exhaust gas duct 4B. An apparatus inlet damper 6 and an apparatus outlet damper 7 are provided in the inlet exhaust gas duct 4A and the outlet exhaust gas duct 4B, respectively. Further, the hot air circulation duct 5 communicates with the inlet exhaust gas duct 4A between the apparatus inlet damper 6 and the exhaust gas treatment apparatus 1, and communicates with the outlet exhaust gas duct 4B between the exhaust gas treatment apparatus 1 and the apparatus outlet damper 6. The hot air circulation duct 5 is provided with a hot air circulation heater 2 and a hot air circulation fan 3. Further, a bypass duct 12 is provided so as to communicate with the inlet exhaust gas duct 4A upstream of the apparatus inlet damper 6 and with the outlet exhaust gas duct 4B downstream of the apparatus outlet damper 7. Further, a hot-air circulation outlet damper 8 and a hot-air circulation inlet damper 9 are respectively provided at the communicating portions of the hot-air circulation duct 5 with the inlet exhaust gas duct 4A and the outlet exhaust gas duct 4B. A bypass inlet damper 15 and a bypass outlet damper 16 are respectively provided at communication portions between 4A and the outlet exhaust gas duct 4B. Examples of the exhaust gas treatment device include an exhaust gas denitration device and a dioxin removal device.
[0005]
In such an apparatus, during steady operation of an incinerator (not shown), the apparatus inlet damper 6 and the apparatus outlet damper 7 of the inlet exhaust gas duct 4A are opened, and the exhaust gas discharged from the incinerator is guided to the inlet exhaust gas duct 4A. The exhaust gas is supplied to the exhaust gas treatment device 1 and processed by the device 1 is further led to a downstream device (not shown) through the outlet exhaust gas duct 4B.
During steady operation of the incinerator, the exhaust gas is supplied to the exhaust gas treatment device 1 to reach a temperature of about 200 ° C., and no corrosion occurs in the exhaust gas treatment device 1, so the hot air installed in the hot air circulation duct 5 The circulation heater 2 and the warm air circulation fan 3 are stopped, and the warm air circulation outlet damper 8 and the warm air circulation inlet damper 9 are “closed” to prevent the exhaust gas from flowing into the warm air circulation duct 5. Further, the bypass inlet damper 15 and the bypass outlet damper 16 are “closed” to prevent the exhaust gas from flowing into the bypass duct 12.
[0006]
However, since the warm air circulation heater 2 and the warm air circulation fan 3 described above are stopped during the operation of the incinerator, the temperature in the warm air circulation duct 5 becomes low, and the hot air circulation ducts have the entrance and exit dampers 8 and 9. There was a problem that the exhaust gas leaked in a small amount in the duct was cooled to generate drainage, and the drain into which HCl and SOx in the exhaust gas had dissolved corroded the members of the hot air circulation duct 5.
On the other hand, when the incinerator is started up, the exhaust gas temperature is low, so the upstream dust collector is often bypassed, and the bypassed exhaust gas must also bypass the denitration device and the dioxin removal device. Therefore, the exhaust gas bypass duct 12 installed for this purpose also has the same problem as the hot air circulation duct 5 because exhaust gas does not flow during steady operation of the incinerator.
[0007]
In order to prevent the corrosion of the duct due to the leakage of the exhaust gas to the hot air circulation duct 5 and the bypass duct 12, a damper having a good hermeticity is provided in a damper provided in each duct communicating with the exhaust gas duct so that the exhaust gas does not leak. The method used is adopted. However, even with a damper specification with good sealing properties, dust accumulated in the take-out seat connected to the exhaust gas duct or dust in the exhaust gas adheres to the damper seal surface when the damper is opened and closed, reducing the sealing performance and leaking the exhaust gas. Since the prevention effect decreases with time and the amount of leakage increases, the occurrence of drain in the duct is inevitable. For this reason, it is necessary to make the duct material an acid-resistant and expensive material, resulting in an increase in apparatus cost.
[0008]
[Problems to be solved by the invention]
The object of the present invention is to solve the problems of the prior art described above and to corrode the exhaust gas treatment device that can also prevent corrosion of the hot air circulation duct and exhaust gas bypass duct attached to the exhaust gas treatment device to prevent corrosion. It is to provide a prevention method.
[0009]
[Means for Solving the Problems]
As a result of intensive studies on the above problems, the present inventors have tried to suck in and circulate outside air into the hot air circulation duct and the exhaust gas bypass duct during operation of the furnace so that the exhaust gas does not flow into these ducts. Thus, the inventors have found that the above-mentioned problems can be achieved, and have reached the present invention.
That is, the invention claimed in the present application is as follows.
[0010]
(1) A method of supplying exhaust gas generated in an incinerator to an exhaust gas treatment device via an inlet exhaust gas duct and discharging the exhaust gas from the outlet exhaust gas duct after the treatment, and when the operation of the incinerator is stopped, In the corrosion prevention method for an exhaust gas treatment apparatus that circulates hot air gas and stops the circulation of the hot air gas during steady operation of the incinerator, the outside air is sucked into the hot air circulation duct during steady operation of the incinerator. And preventing the exhaust gas from flowing into the warm air circulation duct.
(2) A method of supplying exhaust gas generated in an incinerator to an exhaust gas treatment device via an inlet exhaust gas duct and discharging the exhaust gas from the outlet exhaust gas duct after the treatment, and through the hot air circulation duct when the incinerator is stopped. Circulating the hot air gas, stopping the circulation of the hot air gas during the steady operation of the incinerator, and further bypassing the exhaust gas treatment device by the exhaust gas bypass duct for the exhaust gas generated at the start of the combustion furnace In the method for preventing corrosion of the apparatus, outside air is sucked and circulated through the hot air circulation duct and the exhaust gas bypass duct during steady operation of the incinerator, and the exhaust gas flows into the hot air circulation duct and the exhaust gas bypass duct. A method for preventing corrosion of an exhaust gas treatment apparatus, characterized by
[0011]
(3) A pipe that connects the hot air circulation duct and the exhaust gas bypass duct is provided, outside air is sucked from an outside air inlet provided in the hot air circulation duct, and the outside air flows into the exhaust gas bypass duct through the pipe. The method for preventing corrosion of an exhaust gas treatment apparatus as described in (2), wherein
(4) When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct is at a positive pressure, the outside air is sucked from the outside air inlet provided in the hot air circulation duct, and the outside air is drawn by the circulation fan installed in the hot air circulation duct. The method for preventing corrosion of an exhaust gas treatment apparatus as described in (1) or (3), characterized in that it is circulated.
[0012]
(5) When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct has a negative pressure, outside air is sucked from an outside air inlet provided in the hot air circulation duct, and the outside air is sucked into the hot air circulation duct of the outlet exhaust gas duct. The method for preventing corrosion of an exhaust gas treatment apparatus according to (1), characterized in that the exhaust gas treatment device is circulated by an induction fan installed downstream of the communicating portion.
(6) When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct has a negative pressure, the outside air is sucked from the outside air inlet provided in the hot air circulation duct and the exhaust gas bypass duct, and the outside air is taken into the outlet exhaust gas duct. The method for preventing corrosion of an exhaust gas treatment apparatus according to (2), characterized in that the exhaust gas treatment device is circulated by an induction fan installed in the downstream of the communicating portion with the hot air circulation duct and the exhaust gas bypass duct.
(7) The method for preventing corrosion of an exhaust gas treatment device according to any one of (1) to (6), wherein the exhaust gas treatment device is an exhaust gas denitration device and / or a dioxin removal device.
[0013]
[Action]
According to the present invention, since the outside air (atmosphere) is sucked and circulated into the hot air circulation duct and the exhaust gas bypass duct, the inside of these ducts can be used even when the airtightness of the closing damper provided in these ducts is low. Exhaust gas does not flow into the pipe, and even if it flows in a little, air does not drain and it does not drain, so duct corrosion does not occur. Therefore, a normal steel plate can be used as the material of the duct, and the apparatus cost can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
Example 1
FIG. 1 is an operation explanatory diagram during steady operation of an incinerator of an exhaust gas treatment apparatus showing an embodiment of the present invention. The operation shown in FIG. 1 is suitable when the gas pressure in the inlet and outlet exhaust gas ducts is positive.
1 differs from FIG. 5 in that the bypass exhaust duct 12, the bypass inlet damper 15 and the bypass outlet damper 16 are not installed in the inlet exhaust gas duct 4A, and the atmosphere is located near the hot air circulation inlet damper 9 in the hot air circulation duct 5. An inlet 10 and an air intake damper 11 are provided, the air intake damper 11 and the hot air circulation outlet damper 8 are “open”, the hot air circulation inlet damper 9 is “closed”, and the hot air circulation fan 3 is activated to evacuate the outside air. This is the point that the air is sucked from the air inlet 11 and is circulated in the hot air circulation duct 5. At this time, the hot air circulation heater 2 is in a stopped state.
[0015]
According to such an operation, during operation of the incinerator, the hot air circulation fan 3 is activated, the outside air is sucked from the air suction port 10 and is circulated in the hot air circulation duct 5, and the outside air is discharged into the hot air circulation outlet. Since the exhaust gas is sent from the damper 8 to the inlet exhaust gas duct 4A, the inflow of the exhaust gas from the hot air circulation outlet damper 8 is prevented, and the sealing property of the hot air circulation inlet damper 9 is lowered and the exhaust gas flows in. However, since the outside air always flows in the hot air circulation duct 5, it is possible to prevent the generation of drainage, and the hot air circulation duct is prevented from corroding.
[0016]
Example 2
FIG. 2 is an operation explanatory diagram at the time of steady operation of the incinerator of the exhaust gas treatment apparatus showing another embodiment of the present invention. The operation shown in FIG. 2 is suitable when the gas pressure in the exhaust gas duct is positive.
2 is different from FIG. 5 in that an air inlet 10 and an air inlet damper 11 are provided in the vicinity of the hot air circulation inlet damper 9 of the hot air circulation duct 5, and further, a hot air circulation inlet damper 8 and a bypass inlet damper 15 are provided. Are provided with a connection duct 13 communicating the hot air circulation duct 5 and the bypass duct 12 and a connection damper 14 in the connection duct 13, and “open” the atmospheric suction damper 11, the connection damper 14 and the bypass outlet damper 16. The hot air circulation inlet damper 9, the hot air circulation outlet damper 8 and the bypass inlet damper 15 are closed, the hot air circulation fan 3 is activated and the outside air is sucked from the air intake port 10, and the hot air circulation duct 5 is This is the point where it is circulated through the bypass duct 12.
[0017]
In such an operation, during operation of the incinerator, the hot air circulation fan 3 is activated to suck in outside air from the air intake port 11, and the outside air is circulated through the hot air circulation duct 5, the connection duct 13 and the bypass duct 12 in order. Since the exhaust gas is fed into the outlet exhaust gas duct 4B via the bypass outlet damper 16, the exhaust gas is prevented from flowing from the bypass outlet damper 16, and the hot air circulation inlet damper 9 and the hot air circulation outlet damper are blocked. 8 and the bypass inlet damper 15 are deteriorated in sealing performance, and even if exhaust gas flows in, outside air always flows through the hot air circulation duct 5 and the bypass duct 12, so that the generation of drain can be prevented. And corrosion of the bypass duct 12 is prevented.
[0018]
Example 3
FIG. 3 is an operation explanatory diagram at the time of steady operation of the incinerator of the exhaust gas treatment apparatus showing still another embodiment of the present invention. The operation shown in FIG. 3 is suitable when the gas pressure in the exhaust gas duct is negative.
3 differs from FIG. 1 in that an air inlet 10 and an air intake damper 11 are provided in the vicinity of the hot air circulation outlet damper of the hot air circulation duct 5, and further, an outlet exhaust gas duct 4 B of the hot air circulation duct 5 is provided. An induction fan 17 is provided in the downstream of the communication portion, the air intake damper 11 and the hot air circulation inlet damper 9 are “open”, the hot air circulation outlet damper 8 is “closed”, and the induction fan 17 is activated. This is the point that outside air is sucked from the air inlet 10 and the outside air is circulated from the hot air circulation inlet duct 9 to the outlet exhaust gas duct 4B.
[0019]
In such an operation, during the operation of the incinerator, outside air is sucked from the air inlet 10 by the activation of the induction fan 17, and the outside air passes from the hot air circulation inlet damper 9 to the outlet exhaust gas duct 4 </ b> B through the hot air circulation duct 5. Since the air is sent in, the inflow of exhaust gas from the hot air circulation inlet damper 9 is prevented, and the outside air always flows into the hot air circulation duct 5 even if the sealing performance of the hot air circulation outlet damper 8 is deteriorated and the exhaust gas flows in. Since it is flowing, drainage can be prevented and corrosion of the hot air circulation duct is prevented. Thus, when the pressure of the exhaust gas duct is a negative pressure, the air can be sucked using the negative pressure, and the warm air circulation fan 3 is not required to be activated.
[0020]
Example 4
FIG. 4 is an operation explanatory diagram at the time of steady operation of the incinerator of the exhaust gas treatment apparatus showing still another embodiment of the present invention. The operation shown in FIG. 3 is also suitable when the gas pressure in the exhaust gas duct is negative.
4 differs from FIG. 5 in that an air intake port 10 and an air intake damper 11 are provided in the vicinity of the hot air circulation outlet damper 8 of the hot air circulation duct 5 and in the vicinity of the bypass inlet damper 15 of the bypass duct 12, respectively. Further, an induction ventilator 17 is provided in the downstream of the communicating portion of the bypass duct 12 and the outlet exhaust gas duct 4B, and the air intake damper 11, the hot air circulation inlet damper 9 and the bypass outlet damper 16 are “open”, and the hot air circulation outlet damper is provided. 8 and the bypass inlet damper 15 are “closed”, the induction ventilator 17 is started, the outside air is sucked from the respective air inlets 10, and the hot air circulation inlet damper 9 and the bypass outlet damper 16 enter the outlet exhaust gas duct 4B. This is the point where outside air is circulated.
Even in such an operation, the same effects as the operation shown in FIG. 3 can be obtained.
[0021]
【The invention's effect】
According to the present invention, during steady operation of an incinerator, it is possible to prevent exhaust gas from flowing into the hot-air circulation duct or bypass duct to generate drainage and corrode the duct, and the equipment including the exhaust gas treatment apparatus can be stabilized. In addition to being able to operate, ordinary steel can be used as the material of the duct, and economical equipment can be supplied.
[Brief description of the drawings]
FIG. 1 is an operation explanatory diagram of an exhaust gas treatment apparatus according to an embodiment of the present invention during steady operation of an incinerator.
FIG. 2 is an operation explanatory diagram at the time of steady operation of an incinerator of an exhaust gas treatment apparatus showing another embodiment of the present invention.
FIG. 3 is a diagram for explaining operation during steady operation of an incinerator of an exhaust gas treatment apparatus showing still another embodiment of the present invention.
FIG. 4 is an operation explanatory diagram at the time of steady operation of an incinerator of an exhaust gas treatment apparatus showing still another embodiment of the present invention.
FIG. 5 is an operation explanatory diagram at the time of steady operation of an incinerator for exhaust gas treatment according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exhaust gas processing apparatus, 2 ... Warm air circulation heater, 3 ... Warm air circulation fan, 4A ... Inlet exhaust gas duct, 4B ... Outlet exhaust gas duct, 5 ... Warm air circulation duct, 6 ... Equipment inlet damper, 7 ... Equipment outlet damper 8 ... Warm air circulation outlet damper, 9 ... Warm air circulation inlet damper, 10 ... Atmospheric inlet, 11 ... Atmospheric inlet damper, 12 ... Bypass damper, 13 ... Connection duct, 14 ... Connection damper, 15 ... Bypass inlet damper, 16: Bypass outlet damper, 17 ... Induction fan.

Claims (7)

A method of supplying exhaust gas generated in an incinerator to an exhaust gas treatment device via an inlet exhaust gas duct and treating the exhaust gas from the outlet exhaust gas duct, and discharging the exhaust gas from the outlet exhaust gas duct when the operation of the incinerator is stopped. In a corrosion prevention method for an exhaust gas treatment apparatus that circulates gas and stops circulation of the hot air gas during steady operation of the incinerator, external air is sucked into the hot air circulation duct and circulated during steady operation of the incinerator. A method for preventing corrosion of an exhaust gas treatment apparatus, characterized in that exhaust gas is prevented from flowing into the hot air circulation duct. A method of supplying exhaust gas generated in an incinerator to an exhaust gas treatment device via an inlet exhaust gas duct and treating the exhaust gas from the outlet exhaust gas duct, and discharging the exhaust gas from the outlet exhaust gas duct when the operation of the incinerator is stopped. Circulating the gas, stopping the circulation of the hot air gas during the steady operation of the incinerator, and further bypassing the exhaust gas treatment device by the exhaust gas bypass duct for the exhaust gas generated at the start of the combustion furnace of the exhaust gas treatment device In the method of preventing corrosion, outside air is sucked into the hot air circulation duct and the exhaust gas bypass duct and circulated during steady operation of the incinerator, and the exhaust gas is prevented from flowing into the hot air circulation duct and the exhaust gas bypass duct. A method for preventing corrosion of an exhaust gas treatment apparatus. A pipe that connects the hot air circulation duct and the exhaust gas bypass duct is provided, outside air is sucked from an outside air inlet provided in the hot air circulation duct, and the outside air flows into the exhaust gas bypass duct through the pipe. The method for preventing corrosion of an exhaust gas treatment apparatus according to claim 2, wherein When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct has a positive pressure, the outside air is sucked from the outside air inlet provided in the hot air circulation duct, and the outside air is circulated by the circulation fan installed in the hot air circulation duct. The method for preventing corrosion of an exhaust gas treatment apparatus according to claim 1 or 3. When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct has a negative pressure, the outside air is sucked from the outside air inlet provided in the hot air circulation duct, and the outside air is communicated with the hot air circulation duct of the outlet exhaust gas duct. 2. The method for preventing corrosion of an exhaust gas treatment apparatus according to claim 1, wherein the exhaust gas treatment apparatus is circulated by an induction fan installed downstream of the first part. When the inside of the inlet exhaust gas duct and the outlet exhaust gas duct has a negative pressure, the outside air is sucked from the outside air inlet provided in the hot air circulation duct and the exhaust gas bypass duct, and the outside air is circulated in the hot air circulation of the outlet exhaust gas duct. The method for preventing corrosion of an exhaust gas treatment apparatus according to claim 2, characterized in that the exhaust gas treatment device is circulated by an induction fan installed downstream of the communicating portion with the duct and the exhaust gas bypass duct. The method for preventing corrosion of an exhaust gas treatment device according to any one of claims 1 to 6, wherein the exhaust gas treatment device is an exhaust gas denitration device and / or a dioxin removal device.

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