JPS6014257B2 - Incomplete combustion furnace for sewage sludge treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an incomplete combustion furnace used in a sewage sludge incinerator.

The present inventor has proposed an energy-saving and
We have developed a new incinerator consisting of a drying furnace, a complete combustion furnace, and an incomplete combustion furnace in order to improve combustion efficiency, reduce the amount of NO produced, and suppress the generation of hexavalent chromium.

This is shown in FIG. That is, in FIG. 1, sewage sludge that has been dehydrated to about 70% water content is stored in hopper A.

A feeding means 1 is provided at the lower part of the hobber, and sewage sludge is fed almost quantitatively onto a fluidized sand bed 2 of a drying furnace B having a fluidized sand bed. Dry sewage sludge gas heated to 350o0 to 400qo is supplied from below the porous bed plate 3, which is the bottom of the fluidized sand layer 2, through the drying gas supply pipe 4, whereby the sand layer is actively fluidized, so that the sewage sludge is The product is dried while being pulverized in a furnace atmosphere of about 35 to 0, and the product is dried at a temperature at which water vapor does not become water droplets, for example, 1
The dry product is suctioned and transferred by a dry product take-out pipe 6 which is sucked by a blower 5 at about 20 qo. A solid separation means such as a cyclone 7 is provided in the take-out pipe 6, and the separated dried sewage sludge solids are supplied to the incomplete combustion furnace C in fixed quantities by a constant volume supply means 8. A branch pipe 10 is provided in the dry sewage sludge gas transport pipe 9, which is the discharge pipe of the blower 5, so that a part of the dry sewage sludge gas is also supplied to the incomplete combustion furnace C. From the air supply pipe 11 provided at the lower end of the incomplete combustion furnace C, preheated air is supplied in an amount of 60% to 95% of the theoretical air amount required for combustion of the received dried sewage sludge solids and gas. The gas is ejected upward through a perforated plate 12 provided in the furnace, and incomplete combustion takes place in the furnace in the absence of air. The products of the incomplete combustion furnace C are transferred to the complete combustion furnace D through an incomplete combustion product take-out pipe 13 provided at the upper part. A branch pipe 14 is provided in the dried sewage sludge gas transport pipe 9, and a part of the dried sewage sludge gas is supplied to the complete combustion furnace D. The amount of air necessary for incomplete combustion of the incomplete combustion products and dried sewage sludge gas received from the air supply pipe 15 provided on the top surface of the complete combustion furnace ○ is supplied with preheated lid air, and the complete combustion furnace ○ is Approximately 800 in the combustion furnace ○
Ensure that complete combustion occurs in the atmosphere at midnight. The products of the complete combustion furnace are suction-transferred by a complete combustion product discharge pipe 16 with a blower 17 installed at the bottom, and passed through a heat exchanger E to the already incomplete combustion furnace C in the dry sewage sludge gas transport pipe 9. After heating the remaining dried sewage sludge gas distributed to the complete combustion furnace D, the solid separation means 18 removes the ash content, and then it reaches the exhaust blower 17 and is discharged.

The heated dry sewage sludge gas is returned to the drying furnace B' having a fluidized sand bed by connecting the transport pipe 19 to the drying gas supply pipe 4, and is used as a drying gas.

Combustion air is fed by a blower 20, passes through an air preheater 21 provided in the complete combustion furnace, and is supplied to air supply pipes 11 and 15.

An incomplete combustion furnace for use in the incinerator described above has been completed according to the present invention.

The incomplete combustion furnace C of the present invention will be explained with reference to FIG. 2 showing an embodiment thereof.

The dried sewage sludge product extraction pipe 6 has a blower 5 and transports the dried sewage sludge produced in the drying furnace. Separate sludge solids.

The separated dried sewage sludge solids are collected in its lower chamber,
A constant amount of dry sewage sludge solids is supplied into the incomplete combustion furnace C by a constant supply means 8 provided at the lower part of the lower chamber, and the incomplete combustion furnace C has an upright cylindrical shape with a skirt. A dry sewage sludge solid supply device 8 end gate is provided in the cylindrical upper peripheral wall of the incomplete combustion furnace in a direction tangential to the circumference. In addition, a branch pipe 10 is provided in the dry sewage sludge gas transport pipe 9, which is the discharge pipe of the blower 5, and a control valve 23 is provided in the core branch pipe, so that a part of the dry sewage sludge gas is supplied to the incomplete combustion furnace C. However, the engine opening of the branch pipe 10 is provided on the upper peripheral wall of the cylindrical shape in a direction tangential to the circumference.

Also, the combustion air fed by the two blowers is heated through the air preheater 21, passed through the control valve 22,
60% to 90% of the theoretical amount of air necessary for combustion of dry sewage sludge solids and gases supplied to the incomplete combustion furnace C is supplied to the incomplete combustion furnace C through the air supply pipe 11.
An air supply pipe 1 is provided with a port at one end on the lower surface of the cylindrical shape, and a perforated plate 12 is provided above the port.

For the incomplete combustion products of the incomplete combustion furnace C, an incomplete combustion product extraction pipe 13 is provided in the hollow part of the cylindrical shape, with its end opening hanging slightly downward from the upper surface.

The outlet pipe 13 is connected to the suction side of the blower 17 either directly as shown in FIG. 2 or indirectly with a complete combustion furnace interposed therebetween as shown in FIG. The products inside are sucked out in constant quantities and actively taken out, and are easily completely combusted in the next complete combustion furnace 0. In the sewage sludge incomplete combustion furnace C of the present invention, constant amounts of dry sewage sludge solids and gas, which are easily combusted, are supplied from around the cylindrical upper part, and the gas contains a large amount of water vapor. However, when there is a lack of air supply, incomplete combustion is carried out smoothly by preheated air uniformly supplied around the circumference from the bottom of the cylindrical shape, and the products are carried out in constant quantities (from the central shaft), resulting in the conventional initial combustion process. It is possible to significantly suppress the generation of N○×, which occurs in large quantities. Furthermore, if the sewage sludge contains chromium compounds, they will enter the incomplete combustion furnace as a solid from the separator 7 and be heat-treated in a reducing atmosphere, so that hexavalent chromium will not be produced and the method of the present invention will not produce hexavalent chromium. As a constituent effect, it remains in the ash of the incomplete combustion furnace and does not transfer to the complete combustion furnace. Therefore, it is remarkable that the generation of hexavalent chromium can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a sewage sludge incinerator developed by the present inventor, and FIG. 2 is a partially sectional side view of an incomplete combustion furnace for treating sewage sludge according to the present invention. C is an incomplete combustion furnace, 5 is a blower, 6 is a dry sewage sludge product take-off pipe, 7 is a cyclone, 8 is a means for supplying a constant amount of dry sewage sludge solids, 9 is a dry sewage sludge gas transport pipe, 10 is a branch pipe, 11 is a combustion air supply pipe, 12 is a perforated plate, 13 is an incomplete combustion product extraction pipe, 17 is a blower, 20 is a blower for air supply, 21 is an air heater, and 22, 23, and 24 are all adjustments. valve. Figure 1 Figure 2

Claims (1)

[Claims] 1. Dry sewage sludge gas from drying furnace B having a fluidized sand bed is connected to the incomplete combustion furnace and complete combustion furnace by a separator and a branch pipe, and is further returned to drying furnace B via a heat exchanger, and The combustion air supply pipe is connected to the complete combustion furnace and the incomplete combustion furnace via a preheater, the dried sewage sludge transfer pipe from the separator is connected to the incomplete combustion furnace, and the incomplete combustion furnace product transfer pipe is connected to the complete combustion furnace. This is an incomplete combustion furnace C used in a sewage sludge incinerator consisting of a series of sewage sludge incinerators, the incomplete combustion furnace C having an upright cylindrical shape, and having a dry sewage sludge solid supply supplied to the upper peripheral wall of the cylindrical shape. An opening at the end of the pipe 8 and an opening at the end of the branch pipe 10 for supplying a part of the dried sewage sludge gas are provided in the tangential direction to the circumference, and an end opening of the combustion air supply pipe 11 is provided on the lower surface of the cylindrical shape. A perforated plate 12 is provided above, and an incomplete combustion product take-off pipe 13 is provided with an end opening slightly hanging down from the upper surface at the central axis of the cylindrical shape. This is an incomplete combustion furnace for sewage sludge treatment.