JPS5917322B2 - High temperature incineration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-temperature incineration method and apparatus using a melting type incinerator that burns waste at high temperature and melts ash.

In such an incinerator, if there is a large amount of nitrogen in the waste (especially in sewage, which contains 2 to 3 parts of nitrogen on a dry matter basis), if the waste is incinerated at a high temperature, it will cause combustion. A high concentration of NOx is generated in the exhaust gas.

Conventionally, exhaust gas containing such high concentrations of NOX was directly released into the atmosphere, polluting the atmosphere and contributing to pollution.

In addition, devices have been proposed that treat such exhaust gas using chemicals such as catalysts and then release it into the atmosphere to prevent it from polluting the atmosphere. This is problematic in that space is required for the equipment and equipment costs are extremely high.

The NOx concentration is proportional to the nitrogen content in the waste for the same combustion.

Therefore, it is necessary to reduce the nitrogen content in the waste before it enters the incinerator.

In view of these problems, the present invention provides a drying process as a pretreatment for incineration in order to reduce the nitrogen content in waste, and a part of the combustion exhaust gas from the melting type incinerator is guided to the drying process. The process evaporates water and converts a portion of the nitrogen content in the waste into NH3K through a reduction reaction, reducing the amount of nitrogen in the waste input to the incinerator, and separating the waste from the combustion exhaust gas discharged from the incinerator. By denitrating the exhaust gas from the dryer using a catalytic denitrification device, NOx can be economically reduced.
The purpose of the present invention is to provide a method for reducing the occurrence of .The details of the method are as follows.

In the figure, 1 is a known melting type incinerator, and 2 is a flue communicating with the lower part of the incinerator.

3 is a heat exchanger provided in the middle of the flue, 4 is an exhaust fan provided in the flue 2, and 5 is a catalytic denitrification device also provided in the middle of the flue.

6 is a dehydrator such as a filter press, and the dehydrated cake that has been dehydrated to a moisture content of 85 to 60 by this dehydrator 6 is sent to a dryer 8 by a screw feeder 7 or the like, and the dryer 8 It is dried by the combustion gas of about 650°C returned from a part through the conduit 13 and has a moisture content of 50.
It is then thrown into the incinerator 1 by the conveyor 9.

In addition, cold air is introduced into the heat exchanger 3 from the cold air introduction pipe 11.
The heat exchanger 3 exchanges heat with the exhaust gas, and the incinerator 1
Exhaust gas at about 1300℃ immediately after being exhausted from
The cold air is preheated to about 650°C and then supplied to the incinerator 1 through a conduit 12.

Further, the exhaust gas from the dryer 8 is guided through a conduit 10 to a suitable location between the heat exchanger 3 and the denitrification device 5 in the flue 2.

The present invention, as described above, returns part of the combustion exhaust gas from the flue to the waste dryer, which dries the waste before incineration, evaporates water, and removes nitrogen from the waste through a reduction reaction. Partially N
Since the amount of nitrogen in the waste is reduced by converting it into H3 gas, less NOx is generated when the waste is incinerated in an incinerator.

Further, as described above, the NH3 gas generated in the dryer 8 and the combustion exhaust gas from the incinerator 1 are sent to the catalytic denitrification device 5, where they are denitrated by a catalytic reaction and reduced to N2.

The reaction at this time is carried out under a catalyst such as iron oxide or platinum at a temperature of 250 to 450°C.
→ It is processed by the reaction H20+N2.

In this way, the method of the present invention introduces a portion of the combustion exhaust gas from the incinerator into the waste before incineration, dries this waste, and converts some of the nitrogen in the waste into NH3 through a reduction reaction. The combustion exhaust gas used for drying is returned to the flue, and then other dilute NOX components are denitrated together with the combustion exhaust gas using a catalytic denitrification device. However, in the case of the method of the present invention, the amount of nitrogen in the waste is reduced before entering the incinerator, and NH3 gas is supplied from a gas cylinder so that the NOx component in the exhaust gas coming out of the incinerator is diluted. It is extremely economical because the amount of water used is reduced.

Furthermore, although NH3 gas has a pronounced foul odor, the denitrification device 5 removes the foul odor at the same time as denitrifying the gas, so it has various effects such as killing two birds with one stone.

[Brief explanation of the drawing]

The drawing is a front view of the device of the present invention. 1... Melting type incinerator, 2... Flue, 5
...Catalytic denitration equipment, 8...Dryer,
10, 12, 13... Conduit.

Claims (1)

[Claims] 1 In a melting type incinerator, a part of the combustion exhaust gas from this incinerator is introduced into the waste before incineration, and this waste is dried and a part of the nitrogen content in the waste is converted to NH3 by a reduction reaction. A high-temperature incineration method characterized in that the combustion exhaust gas that has been converted and used for drying is returned to the flue, and then denitrated together with other combustion exhaust gases containing dilute NOx components in a catalytic denitrification device.