JPS593504B2 - Municipal waste pyrolysis furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pyrolysis furnace for municipal waste, and more specifically,
This invention relates to a vertical retort-type municipal waste pyrolysis furnace that pyrolyzes municipal waste by external heating.

Because urban tomi occurs in close contact with human life, its properties often change significantly depending on factors such as the living environment, the seasons, the weather, and the number of storage days.

For example, in the case of raw garbage, the moisture content may reach 40% or more, but in the case of dry garbage, the moisture content may be less than a few pounds.

In addition, the physical properties of waste, such as compressibility, vary significantly depending on the type of waste, and the apparent density varies greatly.

When treating such municipal waste in a pyrolysis furnace, pretreatment such as sorting bottles and cans and crushing bulky waste is carried out.

However, operations such as adjusting the moisture content and equalizing the apparent density, which significantly affect thermal decomposition, are rarely carried out because the pretreatment process becomes complicated and the processing cost increases significantly.

The reaction that occurs in the retort of a municipal waste pyrolysis furnace is not simple, but it can be explained by Tang and Bacon.
acon) paper (Preparation ande
valuation of activated ca.
rbon Produced from munic
ipal refuse, PB-221,17
2 page 8, 1973), as well as N.D. McIntyre (A-D, McIntyre) and M.M. Papi.
c) paper (Pyrolysis of munici)
pal solid waste °The Canada
ian Journal of Ch-emical
Engineering: 52 (2) P 2
65-266.1974).

In urban areas, the processes of evaporation of water, dehydration of inherent water, thermal decomposition, and water gasification reactions are repeated in sequence.

The reaction formula will be explained below.

Evaporation of attached moisture (evaporation zone) 25-150℃ Dehydration of cellulose 150-240℃
-0, C-C bond breakage Tar, CO2, CO2H2 (heat generated at 250°C or higher, zone release), cyclization (graphite crystallization at 400°C or higher), converted to graphite, and further converted to water vapor at 500°C or higher. Water gasification reaction 0+H・'CO+H・ ) (aqueous Gaphia zone) C+
2 H20? 'C02+ 2 H2 is occurring.

Since the required amount of heat in the three zones, ie, the evaporation zone, pyrolysis zone, and water gasification zone, is not necessarily constant, it is desirable to provide a heat flux that corresponds to the required amount of heat in each zone.

Conventional municipal waste pyrolysis furnaces have heating means only in the lower part, and are designed so that the total amount of heat is balanced by providing a margin for the heat transfer area of the retort.

In such conventional pyrolysis furnaces, a change in the composition of the waste immediately affects the residue and gas composition, which has the disadvantage of prone to unstable operation.

In addition, there was a drawback that operation troubles were likely to occur due to the formation of bridges in the retort due to caramelization of sugars in the waste or the formation of plastic zones.

An object of the present invention is to provide a pyrolysis furnace for municipal waste that can operate stably by eliminating the drawbacks of the prior art described above.

The present inventor has solved the above-mentioned drawbacks by providing a heating means in the upper part of a pyrolysis furnace for municipal waste, applying a high heat flux, and extracting at least a part of the moisture and cracked gas generated by the heating means to the outside of the system. We found that the following can be solved all at once.
This has led to the present invention.

That is, the present invention provides a pyrolysis furnace for municipal waste that heats municipal waste and sequentially performs evaporative pyrolysis of moisture and water gasification reaction. A first heating means for heating the waste to evaporate moisture is provided below the input port of the retort and above the first heating means, and the moisture generated by the first heating means and An opening is provided for extracting the decomposed gas to the outside of the system, and a second heating means is further provided on the outer periphery of the lower part of the retort to heat the waste in the retort for thermal decomposition and/or water gasification. This is a pyrolysis furnace for municipal waste that is characterized by:

In the pyrolysis furnace of the present invention, the first heating means is provided in the upper part of the decomposition furnace to apply a high heat flux, so that the evaporation of water from the waste is promoted and the abnormal increase in pressure inside the retort is prevented. However, there is a risk of explosion or other danger, so some of the moisture and cracked gas generated by the first heating means is removed from the system at a location below the retort inlet and above the first heating means. An opening was provided for extraction.

By providing this opening, water that has a large effect on thermal decomposition is removed, so that thermal decomposition and water gasification reactions can be stabilized.

Furthermore, by preventing water vapor from condensing due to water vapor filling the dust, it is possible to reduce changes in frictional resistance between the dust and prevent unbalance in descending speed.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

A cylindrical pyrolysis tower 5 having bottom plates at the upper and lower ends is provided on the outer periphery of the retort 3 whose upper end is expanded to form an input port 3A.

Two upper and lower baffle walls 6 are provided in this pyrolysis tower 5 to form upper, middle, and lower three heating chambers 5A, 5B, and 5C. They are communicated through a communication notch 6A provided in a part of 6.

Further, combustion gas from the upper burner 8 as a first heating means is introduced into the upper heating chamber 5A, and combustion gas from the lower burner 7 as a second heating means is introduced into the lower heating chamber 5C. Gas is introduced into the heating chamber 5B at the center, and there are communicating cutouts 6A in the upper and lower baffle walls 6.
The combustion gas that has passed through the upper and lower heating chambers 5A and 5C is guided from the heating chambers 5A and 5C.

One end of a flue 10 is opened to the atmosphere, and the other end of a flue 10 is opened to the central heating chamber 5B, so that the combustion gas is discharged to the atmosphere.

Below the input port 3A of the retort 3 and above the thermal decomposition column 5, there is a slit-shaped opening 1 extending over almost the entire circumference.
1 is formed on the outer periphery of this opening 11.
A cylindrical steam extraction flue 9 is provided surrounding the steam extraction flue 9, and one end of a pipe 12 is connected to the steam extraction flue 9.

A gas reservoir enclosure 14 is connected to the lower part of the retort 3, and the lower end of the gas reservoir enclosure 14 is connected to a hopper 1 that stores water.
7 and is sealed with water.

Further, a rotary valve 15 is rotatably provided above the water sealing surface of the gas reservoir enclosure 14, and a pipe 13 further above the rotary valve 15 is for discharging the gas accumulated in the gas reservoir enclosure 14. is provided.

At one end of the rotating shaft 15A of the rotary valve 15,
A gear 16 is rotatably mounted and rotated by a drive source (not shown).

Inside the hopper 17, a part of an endless conveyor 18 guided by a plurality of pulleys 18A is disposed so as to run below the lower end opening of the gas reservoir enclosure 14, and the other part of the conveyor 18 is guided by a plurality of pulleys 18A. It is arranged to circulate around the outer periphery of the hopper 17.

Further, the garbage 4 thrown into the retort 3 is
The packet 2 extends above the input port 3A of the retort 3 on one side, and is carried by a packet 2 running on a rail 1 whose tip is bent toward the input port 3A.

In addition, the code|symbol 19 shows a residue.

Next, the operation of this embodiment will be explained.

A packet 2 moving up and down along a rail 1 transports waste 4 into a retort 3 in a pyrolysis tower 5 through an input port 3 at the upper end of the retort 3.
Insert from A.

On the other hand, the retort 3 is heated by combustion gas from the upper burner 8 as the first heating means and the lower burner 7 as the second heating means.

The combustion gas that has entered the upper and lower heating chambers 5A and 5C passes through the opening 6A of the wall 6 by the baffle wall 6, gives heat to the retort 3 while moving in a zig-saggy manner, and flows from the central heating chamber 5B to the flue. 10 and is released into the atmosphere.

At this time, heat can also be recovered from the flue 10.

The changing states of the waste 4 in the retort 3 are indicated by A, B, and C.

That is, in the upper part of the retort 3, water mainly evaporates from the municipal waste 4, so it is called an evaporation zone A.

This evaporation zone A almost corresponds to the heating chamber 5A in the upper part, and the municipal waste 4 whose moisture has been evaporated in the evaporation zone A is stabilized and mainly undergoes thermal decomposition corresponding to the heating chamber 5B in the almost central part. It is introduced into pyrolysis zone B.

In pyrolysis zone B, dehydration of inherent moisture, gasification, and graphitization occur.

This graphitized waste 4 is introduced into a water gasification zone C where it reacts with water at high temperature and undergoes hydrogen and carbon monoxide gasification.

This water gasification zone C corresponds to the lower heating chamber 5C.

The water vapor generated in the evaporation zone A, low boiling point volatiles, and some cracked gas rising from the pyrolysis zone B are passed through an opening 11 carved all around the upper part of the retort 3 to a steam extraction flue 9.
The gas enters the system and is further exhausted to the outside of the system through the pipe 12.

The residue of the municipal waste 4 that has undergone the series of physical and chemical changes described above is discharged from the rotary valve 15.

The lower end of the retort 3 is sealed with water in the hopper 11 and is isolated from the outside air, thereby preventing outflow of gas and incorporation of air.

The rotary valve 15 is located between the water seal surface and the gas reservoir surround 14, and its rotation is transmitted through a gear 16.

The residue 19 accumulated at the bottom of the hopper 17 is discharged via a conveyor 18.

On the other hand, the pyrolysis product gas separates the residue 19 in the gas reservoir 14 and is discharged to the outside of the system through the pipe 13.

These series of municipal waste pyrolysis operations may be performed continuously, but discontinuous operation can also be applied.

Further, the heating means is not limited to a burner, and may be other means such as a heating wire, but a burner is more advantageous in terms of equipment.

Next, the method according to the present invention having upper and lower twist combustion chambers (method 2) and the conventional method having only a lower combustion chamber (method 2) will be compared based on examples.

Municipal waste was mechanically crushed and used as garbage.

The moisture content of garbage is 42.6%, and the processing amount is 18% per hour.
It was 0Kp.

In addition, the retort used in this experiment has a cross-sectional shape with a width of 300 mm.
A rectangle with a length of mm1 and a length of 3000 mm, and a height of approximately 7000 mm.
mm, and the temperature was measured approximately at the center of the width of 300 mm.

Therefore, the temperature difference between this central part and the vicinity of the furnace wall is very large, and the temperature near the furnace wall is several times higher than the measured temperature. The temperature of the furnace wall at that point was 950°C, which was sufficient to generate water gas.

Furthermore, the calorific value of the fuel is approximately 20. OOOKca
l/h, most of which uses carbonized gas, making it almost self-sufficient.

The results are shown in Table-■. As described above, the present invention has better heat transfer than the conventional method, and the amount of decomposed gas is three times as large, and the condensed gas is partially gasified, so the amount is reduced by 10%.

This reduction in the amount of condensed gas reduces the load on the gas purification process.

The present invention has the above-described structure and operation, which enables stable operation regardless of compositional changes such as the adhering moisture content of waste, and has the effect of preventing caramelization of sugars in waste or the formation of plastic zones. has.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of a pyrolysis furnace according to the present invention. 1: Rail, 2: Packet, 3: Retort, 3A: Inlet, 4: Garbage, 5: Pyrolysis tower, 6: Baffle wall, T: Lower burner, 8: Upper burner, 9: Steam extraction flue, 10 : Flue, 11: Opening, 12: Pipe, 13: Pipe, 14:
Gas reservoir part, 15: rotary valve, 16: gear,
17: Potspur, 18: Conveyor.

Claims (1)

[Claims] 1. In a municipal waste pyrolysis furnace that heats municipal waste from the outside and sequentially performs water evaporation, thermal decomposition, and water gasification reactions, a cylindrical retort with a waste input port at the top and a cylindrical retort with a waste inlet inside the retort A first heating means for heating the waste to evaporate moisture is provided below the input port of the retort and above the first heating means, and the moisture generated by the first heating means and An opening is provided for extracting the cracked gas out of the system, and the waste in the retort is heated to thermally decompose and/or the waste inside the retort.
Alternatively, a pyrolysis furnace for municipal waste, characterized in that it is provided with a second heating means for water gasification.