CN1298438A - Installation for thermolysis processing of waste with fumes that have a low free oxygen content - Google Patents

Abstract

The installation comprises: a thermolysis chamber, a combustion chamber that is connected to the thermolysis chamber for the combustion of thermolysis gas and to provide a supply of combustion gas, a turbulent burner mounted on the combustion chamber for the combustion of gas resulting from the thermolysis chamber, an afterburn chamber that it connected to the combustion chamber so that part of the combustion gas produced in said chamber can undergo post=combustion, whereby the other part of the gas is introduced into the thermolysis chamber, a preheated combustive oxygen supply line for the burner and means for adjusting the amount of oxygen that it supplied to the burner of the combustion chamber in order to produce combustion gas that is practically devoid of free oxygen at the exit thereof.

Description

Garbage thermal decomposition treatment equipment with low free oxygen content smoke

The invention relates to the pyrolysis treatment of waste, such as industrial waste and/or municipal waste.

According to document EP-A-0524847, an industrial waste and/or municipal waste treatment plant comprises in particular a waste treatment plant with a vertical moving bed pyrolysis reactor.

Rather, waste is fed from the upper part of the pyrolysis reactor and enters the essentially vertical reactor under the force of gravity. The hot gas is input from the lower part of the reactor in the form of an updraft passing through the garbage bed, and gradually supplies its energy to the solid material. According to one embodiment of the plant (plant shown in Figure 2 of said document), said hot gas consists essentially of the effluent from the combustion of pyrolysis waste in a fluidized bed with controlled oxygen content. The control of the oxygen content is carried out by means of a feedback loop.

Hot solids consisting mainly of coke and minerals are discharged through a line at the bottom of the reactor.

According to this document, some wastes have non-uniform characteristics that cause large variations in the calorific value of the pyrolysis gas. Therefore, burning these materials with a burner can cause flame stability problems.

Therefore, the fluidized bed should be selected, because the thermal inertia of the fluidized bed is large, even if the calorific value of the gas to be combusted is significantly reduced, it can ensure the stable combustion of the pyrolysis gas.

As mentioned above, a part of the smoke produced by the fluidized bed reactor is led to the waste thermal decomposition reactor, and another part of the smoke is used for preheating the combustion air. The amount of combustion air fed to the fluidized bed reactor is therefore adjusted such that the pyrolysis gas always has a low oxygen content, as described above.

According to said document, the oxygen content of the hot gas used for pyrolysis is less than 10%, preferably less than 4% by volume.

The present invention aims to improve such equipment.

For this reason, the present invention proposes a kind of thermal decomposition treatment equipment of rubbish, this equipment comprises:

- a waste pyrolysis chamber for thermal decomposition by direct contact with a hot gas,

- an input line for the input of hot gases into the pyrolysis chamber,

- an exhaust line for exhausting gases from the pyrolysis chamber,

- a combustor in fluid communication with the discharge line for combustion of gas from the thermal decomposition chamber and in fluid communication with the input line for supplying combustion gas,

It is characterized by:

- a turbulence burner is installed on the combustion chamber and is connected to the discharge line in order to burn the gas from the thermal decomposition chamber,

- an afterburner in fluid communication with the combustion chamber, suitable for afterburning a part of the combustion gases generated in the combustion chamber and feeding another part of the combustion gases into the inlet line,

- a supply line to the burner with combustion oxygen preheated at a predetermined temperature, and

and a pair of regulating means for regulating the amount of oxygen supplied to the combustor burners for producing combustion gases substantially free of free oxygen at the outlet of said combustor.

According to such an arrangement, the oxygen content of the combustion gas fed into the thermal decomposition chamber can be optimally controlled. In particular, the turbulent burner allows an optimal mixture of combustion oxygen and combustible pyrolysis gases diluted in a large volume of inert combustion fumes from a previous treatment cycle for optimum combustion.

Thus, using the regulating means, the amount of combustion oxygen supplied to said burner can be well adjusted so that the combustion gas for input to the thermal decomposition chamber is substantially free of free oxygen.

In addition, for combustion gases or fumes that do not enter the pyrolysis chamber, afterburning can make the anoxic combustion that occurs in the combustion chamber more complete.

Thus, at the outlet of the afterburner there are combustion gases or fumes whose thermal energy can be utilized directly without further treatment.

Depending on the optimal configuration, the following can be combined:

- a heat exchanger arranged on the inlet line for preheating the combustion air to 600°C to 800°C;

- The burner is also supplied with propane gas or natural gas;

- The combustion gas entering the thermal decomposition chamber is kept at 450°C to 750°C, preferably around 650°C;

- The thermal decomposition chamber is maintained at a constant pressure of 100 mbar to 1.2 bar;

- The afterburner supplies heat to a steam generator;

- the residual solids from the pyrolysis chamber are sorted and the resulting carbonaceous residual solids are fed to another combustion chamber for combustion, which also supplies heat to another steam generator;

- The steam from each steam generator is collectively used in the form of energy to generate electricity.

The last few configurations described allow all combustible materials from waste to be combusted in situ to produce steam for electricity generation.

The pyrolysis chamber may be horizontal, wherein the material is carried by trailers which are moved through the pyrolysis chamber by a mechanical device. In this case, fluid connection means are provided which are adapted to establish a fluid connection between the feed line and a connection area which is arranged on the trailer and communicates with the solids receiving area of the trailer.

According to another embodiment, the pyrolysis chamber is constituted by a charged furnace comprising:

- a waste filling opening that can be sealed closed,

- a discharge port that can be sealed and closed to discharge the residual solid material of thermal decomposition in the furnace,

- a receiving device for receiving a fixed charge of waste in the furnace,

- input means for the recirculated pyrolysis gases constituting the hot gases to be fed into the furnace and directly into the stationary charge for thermal decomposition by direct contact of the waste with said hot gases, and

- Exhaust device for exhausting pyrolysis gas formed by pyrolysis treatment of waste in the furnace.

Such ovens are particularly advantageous in that they can handle bulky waste such as tyres. In particular, this furnace solves the problem of clogging of the feed and discharge systems of vertical fluidized bed furnaces, such as those proposed in the aforementioned document EP-A-0524847, when the material is inhomogeneous, ie of irregular particle size.

Advantageously:

- The receiving device is movably installed between the garbage receiving position during thermal decomposition treatment and the discharge position where the thermal decomposition residual solid material is discharged through the discharge port;

- the receiving device is equipped with means for the circulation of hot gas towards the solid charge of refuse; the input device feeds the hot gas under the receiving device;

- The cooling device is arranged under the furnace to cool the residual solid material from thermal decomposition.

Other objects, features and advantages of the present invention will be better understood with reference to the attached drawings and non-limiting examples.

The accompanying drawings are as follows:

Fig. 1 is a schematic diagram of a device according to a preferred embodiment of the present invention;

Fig. 2 is a schematic longitudinal sectional view of a packed thermal decomposition furnace of the present invention.

Figure 1 shows a preferred embodiment of the device of the invention.

In this plant, the waste to be processed is fed into a shredder 9 and then loaded onto a trailer 11 via a conveyor system 10 .

The trailer 11 used in the plant shown in Figure 1 can be, for example, that described in document WO-98/16594, allowing the direct introduction of hot gas into the waste charge to be treated.

The trailers 11 loaded with refuse are fed one after the other into a pyrolysis chamber or furnace 12, which is provided with a sealed charging door 13 for this purpose.

When a trailer is sent into the pyrolysis furnace 12, in order to avoid oxygen entering the furnace, the trailer 11 can be sent into the furnace 12 by a charging machine (not shown), wherein the trailer 11 is in an inert atmosphere middle. When the cart 11 is brought into the furnace 12, means for establishing a sealed connection between the furnace 12 and the charging machine, for example a telescoping tube, unfolds in order to feed the cart 11 towards the furnace 12 in an inert atmosphere.

The apparatus according to the invention comprises an inlet line 14 for feeding the hot gas into the pyrolysis furnace 12 . As will be described in detail below, the hot gas is composed of combustion gas produced by combustion of the pyrolysis gas previously exhausted from the pyrolysis furnace 12 .

The input pipeline includes branch pipes 14a to 14i, and the terminal of each branch pipe is a fluid connection device (such as a telescoping tube, not shown in Fig. A temporary fluid connection is established between a connection area that communicates with a waste receiving area. As mentioned earlier, this allows hot gases to be injected directly into the waste charge for pyrolysis.

Hot gases (combustion gases, hereinafter also referred to as "smoke") are fed at a temperature of 450° C. to 750° C., preferably at a temperature of about 650° C., into the pyrolysis furnace 12, which is maintained at a pressure of 100 mbar to 1.2 bar. constant pressure.

Thus, as each trailer 11 enters the pyrolysis furnace 12 and is connected to the successive branches 14a-14i of the input line 14, the waste is first dehydrated and then heated to its pyrolysis temperature.

After treatment, each trailer 11 containing the residual solid material is recovered under an inert atmosphere, for example by means of a charging machine, at a location of a sealed discharge door 15 of the furnace 12 .

The treatment of residual solid materials will be described in detail below.

Pyrolysis gases formed in the furnace 12 are discharged from the furnace through a discharge line 16 having branches 16a-16i. The discharge of the pyrolysis gases takes place by means of a suction device arranged on the discharge line 16 . These suction devices are not shown in FIG. 1 and can be formed, for example, by a booster.

The inlet line 14 and the discharge line 16 are preferably insulated so that on the one hand the high-temperature pyrolysis gas enters a combustion chamber to be described below, and on the other hand the hot gas to be imported into the pyrolysis furnace 12 remains at a high temperature .

The pyrolysis gas from the pyrolysis furnace 12 is conveyed via a discharge line 16 to a powder sorter 17 . After removal of fines, the pyrolysis gas is fed from a combustion chamber 19 into a burner 18 via a line 20 .

Burner 18 is a turbulent flow burner such as that produced by BLOOM.

The burner 18 also has an inlet 21 for propane gas or natural gas, which can be added, inter alia, to ensure the maintenance or piloting of the flame and to initiate the pyrolysis process.

A combustion oxygen supply line 22 is also connected to the burner 18 . The combustion oxygen can be pure oxygen or come from air or oxygen-enriched air.

The combustion oxygen is preheated to 600 to 800° C. before being fed into the burner 18 . To this end, the supply line 22 leads to two heat exchangers 23 , 24 , to an afterburner 25 and then to the burner 18 .

More precisely, the combustion oxygen supply line 22 is connected to an additional burner 26 of the afterburner 25 and to a hearth 27 of the afterburner 25 , which hearth 27 is connected to an outlet 28 of the burner 19 .

In this regard, it should be noted that, in other embodiments, a smoke delivery line may separate the hearth 27 and thus the afterburner 25 from the outlet 28 of the burner 19 .

The burner 26 is also provided with a propane gas or natural gas inlet 29 connected to the same gas source as the inlet 21 of the burner 18 .

The oxygen quantity regulating means provided to the burner 18 of the combustion chamber 19 is also used to generate combustion gas at the outlet of the combustion chamber 19 substantially free of free oxygen (preferably less than 0.5% oxygen content). In a preferred embodiment of the invention, the regulating means are also used to generate the amount of oxygen supplied to the afterburner 25 .

For example, an oxygen meter 30 can be provided, which is arranged on the input line 14, arranged at the outlet of the combustion chamber 19, and is connected to a servo-operated valve system 31 arranged in the combustion chamber. Oxygen supply line 22. For simplicity, the connections between the oxygen meter 30 and the servo-operated valve system 31 are not shown in FIG. 1 .

A part of the combustion gases or smoke from the combustion chamber 19 is thus discharged from the combustion chamber via the line 14 , which is provided with a suction device 32 for this purpose. Another part of the fumes for recirculation in the pyrolysis furnace 12 is sent to the afterburner 25 for complete combustion and reuse, as will be described below.

The smoke from the combustion chamber 19 and the smoke from the post-combustion chamber 25 pass through heat exchangers 23 and 24 respectively to preheat the combustion air to 600 to 800° C. For this purpose, one end of the combustion oxygen supply line 22 is connected to an oxygen source 33, A pump unit 34 follows, passing through heat exchangers 23 and 24 and on to burners 18 and 26 .

In other embodiments, it is obviously possible to use a single double-circuit heat exchanger instead of heat exchangers 23 and 24, or even to use only a single-circuit heat exchanger.

The plant shown in Figure 1 is intended to treat all pyrolysis materials on site, the fumes exiting the afterburner 25 are conveyed through a line 35 through the heat exchanger 24 to a water-supplied double-circulation boiler type, for example at 37. Steam generator 36.

In this case, the steam produced is supplied to the turbine alternator unit 38 to generate electricity. The condensed water produced by the generator set is discharged through the pipeline 39. In other embodiments, it is apparent that the smoke from the afterburner 25 could be used to produce hot water instead of generating electricity.

Cooled fumes are discharged from the steam generator 36 through a line 40 provided with a suction device 41, are conveyed to an in-line filter 42, which separates solid particles, and are then discharged into the atmosphere through a chimney 43.

The suction device 41 , formed for example by an exhaust fan, also regulates the separation between the fumes for the furnace 12 , in which the flow is pressure-controlled, and the fumes for the afterburner 25 .

In addition, safety procedures especially concerning the suction device or exhaust fans 32 and 41 prevent oxygen from the afterburner 25 from entering the combustion chamber 19 .

Each trailer 11 containing the thermally decomposed residual solid material is transported through the charging machine to a cooling device 44, which is also configured to avoid free oxygen from entering the charging machine.

Once in the cooling unit 44, the trailer 11 is inclined on a conveyor which passes the residual solid material into a pool 45 for cooling.

These residues are then washed at reference number 46 and screened at reference number 47 . The aperture of the sieving machine is here 8 mm. The particles that pass through the sifter pass through a crushing stage at 48 and are re-screened by a sifter 49 with an aperture of 0.8 mm. Through this screening, carbonaceous substances are separated from inorganic substances.

The carbonaceous material passes through a draining stage at 50 and is sent to a silo 51 for storage. The inorganics pass through a sorting stage at 52. After sorting, the mineral matter is recovered at 53, the magnetic material is recovered at 54, and the non-magnetic material is recovered at 55. During sorting, these substances also go through a compaction stage.

Particles screened by the screening machine at 47 are sent to a flotation cell 56 .

The densest substances (metals, etc.) are recovered at the bottom of the flotation cell and sent to number 52 for separation. The least dense material (carbonaceous material) is recovered in the upper part of the flotation cell 56, sent to a pulverizer 57, and pulverized to a particle size of less than 0.8 mm.

These carbonaceous particles are then also drained at 50 and sent to silos 51 .

The silo 51 feeds a compact fluidized bed furnace 58 for burning the carbonaceous material or carbon stored in the silo 51 .

Fumes generated in the furnace 58 pass through a steam generator 59 supplied with water at 60 . The steam exhausted from this generator 59 is sent to the turbine alternator unit 38 together with the steam exhausted from the generator 36 .

The smoke generated in the furnace 58 also flows through a preheater 61 which preheats the combustion oxygen for the furnace 58 . Combustion oxygen is fed into the furnace 58 through a line 62 which is connected to a source 63 of pure oxygen, pure air or oxygen-enriched air and is provided with a suction device 64 .

The smoke from the preheater 61 is conveyed to the line filter 42 via a line 65 provided with a suction device 66 .

The slag recovered at the bottom of the furnace 58 is discharged and collected at 67, while the slag recovered at the upper part of the furnace 58 is recycled through a line 68 within the furnace.

In addition, one end of the pipeline 68 is also connected to the bottom of the pipeline filter 42 .

The remainder of the residue that is removed from the bottom of the in-line filter 42 is removed at 69 .

According to another embodiment shown in FIG. 2 , the pyrolysis chamber is constituted by a packed pyrolysis furnace 112 .

The furnace 112 is vertical, and its upper and lower ends are hermetically closed by movable plates 170, 171 that move on a horizontal plane when performing thermal decomposition.

The plate 170 can close the charge opening of the furnace 112, substantially transverse to the longitudinal axis of the furnace 112, while the plate 171 serves to close the discharge opening of the furnace 112, also substantially transverse to said axis.

The discharge port leads to a thermal decomposition residual solid material recovery pool 172 .

In order to intermittently receive the fixed charge of garbage to be processed, a fixed collector 173 is installed between the plates 170 and 171 in the furnace 112 .

The bottom of the accumulator 173 is formed by a partition 174 which is divided into two parts. Each of the two parts of the divider 174 is rotatable between a horizontal position, in which they abut each other, to receive waste charges, and a position apart from each other, in which the plates 171 After being drawn out, the material is discharged through the discharge port.

A side inlet 175 for recirculated pyrolysis gas leads to the furnace 112 below the partition 174 . When the furnace 112 replaces the horizontal furnace 12 shown in FIG. 1 , the inlet is connected to the input line 14 of the apparatus shown in FIG. 1 . In this way, the recirculated pyrolysis gas enters the waste charge after passing through the partition 174, and the hot gas is directly contacted with the fixed charge of waste to be treated for thermal decomposition.

The pyrolysis gases formed in the furnace 112 are discharged from the furnace through a lateral outlet 176 which is connected to the discharge line 16 in the case of the furnace 112 used in the plant shown in FIG. 1 .

The furnace 112 is supplied with waste by gravity through a charging machine 177 movable horizontally above the furnace 112 under the action of gravity.

For this purpose, an accumulator 178 similar to the accumulator 173 is installed in the charging machine 177 . In this regard, it should be noted that the lower end of the charging machine 177 is not closed.

According to other embodiments, the charging machine can be replaced by a charging machine that feeds the furnace from a side opening via a conveyor belt.

This charging machine can also be installed in a translational manner so as to feed a group of thermal decomposition furnaces.

It is also possible to feed hot gas into the charge from the side.

Residues can also be discharged laterally via a waste receiving plate mounted on a tilting slide.

It should be pointed out that the examples described here are only non-limiting examples, and that many other example variants can be suggested by those skilled in the art without departing from the scope of the present invention.

Claims (13)

1. A thermal decomposition treatment device for garbage, which includes: - a waste thermal decomposition chamber (12) for thermal decomposition by direct contact with a hot gas, - an input line (14) for the input of hot gases into the pyrolysis chamber, - an exhaust line (16) for exhausting the gases in the pyrolysis chamber, - a combustion chamber (19) in fluid communication with the discharge line (16) for combustion of the gas from the thermal decomposition chamber (12) and in fluid communication with the input line (14) for supplying Combustion gases produced by combustion of gases from the thermal decomposition chamber (12); characterized by: - a turbulent burner (18) mounted on the combustion chamber (19) and connected to the discharge line (16) in order to burn the gas from the thermal decomposition chamber (12), - an afterburner (25) in fluid communication with the combustion chamber (19), suitable for afterburning a part of the combustion gases generated in the combustion chamber (19) and feeding another part into the input line (14) , - a supply line (22) for supplying the burner (18) with combustion oxygen preheated at a predetermined temperature, - Regulating means for regulating the amount of oxygen supplied to the burner (18) of the combustion chamber (19) for generating combustion gases substantially free of free oxygen at the outlet of said combustion chamber (19). 2. Apparatus according to claim 1, characterized in that the thermal decomposition chamber consists of a packed furnace comprising: - a waste filling opening that can be sealed closed, - a thermal decomposition residual solid material outlet that can be sealed and closed, - a receiving device (174) for receiving a fixed charge of refuse in the furnace, - input means (175) for the recirculation of pyrolysis gases constituting the hot gases into the furnace and directly into the stationary charge for thermal decomposition by direct contact of the refuse with said hot gases, - Exhaust device (176) for exhausting pyrolysis gas formed in the furnace by pyrolysis treatment of waste. 3. Device according to one of the preceding claims, characterized in that a heat exchanger (23, 24) is arranged on the supply line (14) for preheating the combustion air to 600°C to 800°C. 4. Device according to one of the preceding claims, characterized in that the burner is also supplied with propane gas or natural gas. 5. Plant according to one of the preceding claims, characterized in that the combustion gases entering the pyrolysis chamber are kept at a temperature between 450°C and 750°C, preferably around 650°C. 6. Device according to one of the preceding claims, characterized in that the thermal decomposition chamber is kept at a constant pressure of 100 mbar to 1.2 bar. 7. Device according to one of the preceding claims, characterized in that the afterburner (25) supplies heat to a steam generator (36). 8. Plant according to one of the preceding claims, characterized in that the residual solid material from the thermal decomposition chamber is sorted and the carbon-containing residual solid material thus obtained is fed into another combustion chamber (58) for combustion, which The chamber (58) also supplies heat to another steam generator (59). 9. Plant according to claim 7 or 8, characterized in that the steam from each steam generator (36, 59) is used collectively in the form of energy to generate electricity. 10. Plant according to claim 1, characterized in that the pyrolysis chamber (12) is horizontal, wherein the refuse is carried by trailers (11) which are moved through the pyrolysis chamber by a mechanical device. 11. The equipment according to claim 2, characterized in that the receiving device (174) is movably installed between the garbage receiving position during pyrolysis treatment and the discharge position where the residual solid material of pyrolysis is discharged through the discharge port. 12. The apparatus according to claim 2 or 11, characterized in that the receiving means are provided with means for the circulation of hot gas towards the solid charge of refuse, and the inlet means feed the hot gas under the receiving means. 13. The equipment according to claim 2, 11 or 12, characterized in that the cooling device is arranged below the furnace for cooling the residual solid material from thermal decomposition.

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