JPS6152883B2 - - Google Patents

Description

Detailed Description of the Invention The present invention prevents the occurrence of secondary pollution by organically combining operations such as drying, solidifying, incinerating, and melting sewage sludge and industrial wastewater sludge. This was done with the aim of minimizing the amount of thermal energy required for the processing by effectively utilizing the heat sources in each facility.

As a conventional incinerator for sewage sludge or industrial wastewater sludge, there is a fluidized bed type incinerator as shown in FIG. As shown in the figure, sludge b introduced from the top of the incinerator a is in a fluidized state due to air c, and high-temperature sand d
It is crushed and heated in the fluidized bed, and self-combusts in the upper part of the fluidized bed. At this time, the water contained in the sludge evaporates and is discharged from the upper part of the incinerator a together with the exhaust gas generated by combustion of the organic matter in the sludge. The high-temperature exhaust gas e discharged from the upper part is accompanied by fine inorganic substances that have turned into ash. According to the above-mentioned incinerator a, (a) the capacity of the device is small because it can perform high-load processing, (b) there is no secondary pollution due to odor because the exhaust gas temperature is high, and (c) it is suitable for deodorizing exhaust gas by incineration. Although it has advantages such as lower fuel consumption compared to
% or more), a considerable amount of the heat input is taken up by the latent heat of vaporization of the water in the sludge. Therefore, in order to achieve self-combustion, it is necessary to introduce heat f through fuel combustion, etc. I need. In addition, high-temperature exhaust gas cannot be recovered as it is, which is very uneconomical, and there is also the problem that harmful components such as heavy metals are discharged into the outside air together with non-flammable inorganic substances.

In order to solve the above problems, a method shown in FIG. 2 has been considered. That is, a pre-dryer h is installed in the upper part of the fluidized incinerator a to dry the sludge b using part of the high-temperature exhaust gas g, and the sludge b is dried as the dried sludge i.
In addition, the exhaust gas j after being dried in the pre-dryer h is circulated to the fluidized bed again for deodorization. Further, the exhaust gas e is separated into gas l and ash m by a cyclone k,
After the separated gas l preheats the combustion air o of the fuel f by a heat exchanger n, it is sent to a gas treatment step p. However, in the above method, the exhaust gas containing steam after drying treatment
Since the sludge is returned to the fluidized bed, there is a limit to the drying of the sludge, and to further dry the sludge, the amount of fuel f must be increased. Furthermore, since the pre-dryer h is mounted on the top, there is a problem in that the height of the equipment increases, and furthermore, the disposal of incinerated ash m, which is a source of secondary pollution, remains a problem. In other words, it is not possible to complete the disposal of the incinerated ash by landfilling, ocean dumping, etc.
It is constrained by land shortages and secondary pollution.

In order to solve the above problems, attempts are currently being made to finalize the material by melting. For example, the third
As shown in the figure, dried sludge or incinerated ash r is put into a closed electric furnace or gas melting furnace q. In the case of dry sludge, organic matter is thermally decomposed or burned to be gasified and sent to exhaust gas treatment, and inorganic matter is melted as slag t. If a closed electric furnace is used at this time, the inside of the furnace is maintained in a reducing atmosphere by the gas generated by the decomposition of organic matter, which facilitates the elution of heavy metals into the slag. On the other hand, in the case of the incineration ash, there is a method in which the input material r contains carbon and the like and is charged into the furnace to create a reducing atmosphere in order to maintain the inside of the furnace in a reducing atmosphere.
The slag t produced in this way is periodically discharged out of the furnace and is recycled through granulation treatment or the like. However, in any of the above melting furnaces, a lot of dust is generated in the furnace, and there is a strong possibility that harmful components are included in the exhaust gas s together with the dust and scattered. Further, there is a problem in that the energy required for processing in the form of electricity or fuel is large, and the running cost is the highest, especially in closed electric furnaces and the like.

The present invention was made to solve the problems of the above-mentioned conventional methods, and includes a device for drying sludge after dewatering, a fluidized bed incinerator for incinerating the sludge after drying, and a fluidized bed incinerator for incinerating the sludge after drying. The apparatus is equipped with a device for sealing and melting incinerated ash in a reducing atmosphere, and pipes for exhaust gas and incinerated ash are provided at the top of the fluidized bed incinerator, a cyclone is connected to the rear of the pipe, and the exhaust gas pipe of the cyclone is connected to the connected to a drying device, further connecting the incinerated ash pipe of the cyclone to the device for sealing and melting processing, and branching the exhaust pipe provided in the drying device into two, one of which is connected to the exhaust gas pipe. The present invention relates to a treatment device for sewage sludge and industrial wastewater sludge, characterized in that the other end is connected to the incinerator.

Embodiments of the present invention will be described below with reference to the drawings.

1 in FIG. 4 is a dryer, and the dryer 1 includes:
There is an inlet 2 for dehydrated sludge and an outlet 3 for sludge particles after drying treatment, and an air supply pipe 4 for introducing drying heat source gas, which will be described later, and an exhaust pipe 5 for discharging exhaust gas after drying treatment are connected. . The discharge port 3 is connected to a sludge transport device 7 that transports sludge particles to a storage hopper 6, and in the middle of the sludge transport device 7 there is a pipe installed at the upper part that guides the exhaust air from the exhaust pipe 5 and separates dust. A lower pipe 10 of a cyclone 9 with a cyclone 8 is connected thereto. The storage hopper 6 is connected to the fluidized bed sludge incinerator 1 via a sludge input and transfer device 11.
2, and an air supply branch pipe 13 for fluidized bed flow and sludge combustion is connected to the incinerator 12. Further, the incinerator 12 is connected to a cyclone 15 that separates incinerated ash via an exhaust gas exhaust pipe 14 provided at its upper part. cyclone 1
5 has a pipe 16 at the top and a hopper 17 at the bottom.
is provided. A suction blower 1 is connected to the pipe 16 in the middle of the pipe 8 above the cyclone 9.
8 and then branched into two directions, one of which is connected to a pipe 19, and the other pipe 20 is connected to the air supply branch pipe 13 of the incinerator 12 via a regulating valve 21 in the middle. has been done. Further, the pipe 16 is branched into the air supply pipe 4 and another pipe 23, which is equipped with a high temperature blower 22 in the middle.
The pipe 23 is connected to a gas absorption tower 27 via a heat exchanger 24, an electrostatic precipitator 25, and a suction blower 26 in this order. A temperature detector 28 such as a thermocouple is provided in the middle of the air supply pipe 4, and the opening degree of the regulating valve 21 is adjusted based on the detected value of the detector 28. Further, air is sent to the heat exchanger 24 via a blower 29, and the heated air is sent to the incinerator 12 via the air supply main pipe 30.
It is configured so that the air is fed to the air supply branch pipe 13 of.

Further, a pipe 31 from the electrostatic precipitator 25 is connected to the hopper 17 at the bottom of the cyclone 15, and the hopper 17 is further connected to a closed melting furnace 33 via an incinerated ash transfer device 32. . Further, the melting furnace 33 has a reducing gas introduction pipe 3.
A digestion holder 35 is connected via 4.

Next, the operation of the present invention will be explained.

Sludge that has undergone dewatering treatment (moisture content approximately 70-80%)
is fed into the dryer 1 from the input port 2, and the air supply pipe 4
The sludge is dried by the high-temperature gas (approximately 700°C) introduced from the sludge, and is discharged from the discharge port 3 as dried sludge particles. After drying, the steam-rich exhaust gas (approximately 200
degree Celsius) is discharged to the cyclone 9 through the exhaust pipe 5, and after the dust is separated in the cyclone 9, it is sucked into the pipe 8 by the suction blower 18. The sludge discharged from the discharge port 3 is transported by a sludge transport device 7 and temporarily stored in a storage hopper 6, and this hopper 6 is also equipped with the cyclone 9.
The separated dust is also stored.

The sludge in the storage hopper 6 is transferred to the sludge input and transfer device 1.
1 is quantitatively cut out and put into the incinerator 12. The sludge introduced into the incinerator 12 is made to flow by heated air supplied through the main air supply pipe 30 and the branch pipe 13, and is crushed by preheated media sand (not shown). Then, the organic content in the sludge is combusted by the heated air, resulting in high-temperature exhaust gas of about 800 to 900°C, which is sucked into the exhaust gas pipe 14 with incinerated ash mixed in as fine dust. The above exhaust gas is cyclone 1
5, the gas is led to the pipe 16, and the incinerated ash is temporarily stored in the hopper 17 together with the dust from the electrostatic precipitator 25.

The exhaust gas separated by the cyclone 15 is mixed with the dried exhaust gas separated by the cyclone 9 and sent through the pipe 19, and the high temperature is used to decompose the odor of the dried exhaust gas. . Further, a part of the dried exhaust gas led from the pipe 8 is sent to the incinerator 12 via the pipe 20 and is deodorized. Since this amount is small, it does not result in a thermal loss of the incinerator 12. Further, in order to keep the temperature of the high-temperature gas introduced into the dryer 1 constant, the regulating valve 21 is operated by a signal from a temperature detector 28 provided in the air supply pipe 4, and the gas mixed into the pipe 16 via the pipe 19 is The amount is being adjusted. A part of the mixed gas in the pipe 16 is passed through the high temperature blower 22.
The air is sucked in as a heat source for the dryer 1 by the suction blower 26, and the air is first introduced into the incinerator 12 by the heat exchanger 24 to be heated for flow and combustion, and then the air is heated by the electrostatic precipitator. After being processed by the gas absorption tower 27 and the like, it is discharged into the atmosphere as exhaust gas. In order to prevent this exhaust gas from turning into white smoke, either the temperature of the gas after passing through the heat exchanger 24 is raised and the gas is discharged, or the heat exchanger 2
After 4, another heat exchanger (not shown) is provided,
The air heated by the passing heat exchanger can also be led to the upper part of the gas absorption tower 27 and discharged. The incinerated ash temporarily stored in the hopper 17 is transferred to a closed melting furnace 33 by a transfer device 32.
The interior of the melting furnace 33 is maintained in a reducing atmosphere by the reducing gas introduced through the reducing gas introduction pipe 34, thereby facilitating the separation of heavy metals. Digestion gas generated in the digestion gas holder 35 is used as the reducing gas. As described above, in the present invention, gas hardly passes through the furnace while the incinerated ash is melted, unlike in the conventional method, so that it is possible to prevent harmful components from scattering.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be modified in various ways without departing from the gist of the present invention.

According to the sewage sludge and industrial wastewater sludge treatment apparatus of the present invention described above, the following excellent effects are exhibited.

(i) Since the sludge dried by the dryer is incinerated, the efficiency of the incinerator can be increased, and preliminary fuel for sludge combustion is not required during normal operation.

(ii) Since the heat source of the dryer uses the exhaust gas from the incinerator, there is no need for any separate heat source for drying except during startup.

(iii) The heat of the exhaust gas at the outlet of the incinerator can be used to deodorize the exhaust gas from the dryer, and since only a small amount of the exhaust gas after drying is partially circulated and introduced into the incinerator, the efficiency of the incinerator is improved. There is no impact. That is, if all the exhaust gas from the dryer were introduced into the incinerator for deodorization, the amount of exhaust gas would be large and the amount of heat loss would increase, but there is no such concern.

(iv) Since only incineration ash is processed in the closed melting furnace, the amount of energy input required for processing can be reduced. That is, when organic components are treated together as in the past, the amount of energy input increases by the sensible heat of the exhaust gas, but this is not the case.

(v) If the gas generated from digestion is used as the reducing gas introduced into the melting furnace, no particular reducing gas generator is required, and moreover, the gas generated from digestion can be used effectively.

(vi) As a result of the above, the overall energy required for sludge treatment can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are schematic explanatory diagrams showing examples of conventional techniques, respectively, and FIG. 4 is a flowchart showing an example of implementing the method of the present invention. 1 is a dryer, 4 is an air supply pipe, 5 is an exhaust pipe, 12 is a fluidized bed sludge incinerator, 16, 19, 20 are piping, 21 is a regulating valve, 23 is piping, 24 is a heat exchanger, 25 is electricity Dust collector, 27, gas absorption tower, 28
30 is a temperature detector, 30 is an air supply main pipe, 33 is a closed melting furnace, and 35 is a digestion gas holder.

Claims (1)

[Claims] 1. A device for drying sludge after dewatering treatment, a fluidized bed incinerator for incinerating sludge after drying,
Equipped with a device for sealing and melting the incinerated ash after incineration in a reducing atmosphere, pipes for exhaust gas and incinerated ash are provided at the top of the fluidized bed incinerator, a cyclone is connected to the rear of the pipe, and a pipe for the exhaust gas of the cyclone is provided. is connected to the drying device, further connecting the incinerated ash piping of the cyclone to the device for sealing and melting processing,
A treatment device for sewage sludge and industrial wastewater sludge, characterized in that an exhaust pipe provided in the drying device is branched into two, one of which is connected to the exhaust gas pipe and the other connected to the incinerator. .