KR960010986B1 - Process and installation for recovering reusable gas from waste through pyrolysis - Google Patents

Abstract

According to a process for recovering reusable gas from waste through pyrolysis, the previously comminuted waste is transformed into fluff, granulates or pellets and introduced into a degassing drum (16), in which low temperature carbonization gas is generated and separated from the residual matter. The low temperature carbonization gas is decomposed into combustion gas in a gas converter (19) and cleaned in a subsequent gas washing installation (21-24 and 47-51) with circulating washing water. Part of the water of the circulation system of washing water is withdrawn and replaced with fresh water in order to limit its concentration of toxic substances. The pyrolysis residues to be withdrawn from the low temperature carbonization drum are withdrawn through a water bath (72). At least part of the quantity of liquid withdrawn from the circulation system of washing water of the gas washing installation (21-24) is introduced in the water bath (72).

Description

[Name of invention]

Method and Apparatus for Producing Usable Gas from Waste by Pyrolyes

[Brief Description of Drawings]

1 shows a schematic of the method and apparatus of the present invention.

* Explanation of symbols for main parts of the drawings

1: Conveyor 2: Coarse Mill

4,7,8: Carrier 5: Magnet Separator

6: separator 9: grinding machine

10: suction line device 13: biogas device

14: spiral heat compressor 15: drainage

16 gas bromine 18: dust separation device

19: gas converter 21: spray device

22: blower 23: washing device

24: droplet separator 25: gas pipe

30 generator 31 gas pipe

38 gas burner 40 washing water tank

46: cooling tower 47: washing water neutralizing device

48: circulating water-conversion processing device 50: circulating pipe

56 gas decomposition device 60: shock absorber

61: compressor 35,62: conveying pipe

66: suction pipe 67: the bottom of the rot chamber

69: dry press 72: water tank

76: ozone injection device 77: lime burning oven

Detailed description of the invention

[Field of invention (technical field)]

The present invention relates to a method for producing a gas usable from waste by pyrolysis using the method described in claim 1. The invention also relates to an apparatus for carrying out the method according to the invention as described in claim 10.

[Problems with Prior Technology]

Methods and apparatus using pyrolysis are already known, for example in DE-OS 33 47 554 and DE-OS 35 445. In this case, usable gases can be obtained from the waste. To this end, a cycle of water required for various stages, especially the amount of water required for the gas waschanlage for the split gas produced in a gas converter, is cycled. However, in the conventional case, in order to maintain a constant level of harmful substances contained in the gas washing device and to guarantee the purity of the gas (Reinheit), it was necessary to remove a certain amount of water circulated and replace it with fresh water. At this time, the extracted water had to be post-treated. For this debris had to be removed. In addition, the concentrations of cyanides (Zyaniden), phenols (Phenolen), and ammonium have been found to be problematic in some cases because of the direct transport to biogas units that move like pyrolysis units. . The above-mentioned change in concentration leads to a decrease in the activity of microorganisms and, in extreme cases, even destroys the environment. Neutralizing chemical Oxidationsstoffe or Flockungasmittel can also increase the amount of residues of special wastes to be removed.

[Purpose of invention]

Accordingly, the object of the present invention is to reduce substances that destroy the environment, which need to be removed while maintaining a manufacturing method containing less waste water, and to significantly improve the operational performance of the apparatus.

[Availability of invention]

The challenge is to transport the pyrolysis residues from the gas-collecting Trommel (Entgasungstrommel) to the Wasserbad. It can be satisfied by replenishing at least a portion of the liquid drawn out from the circulating water in the gas washing apparatus.

In this way, pyrolysis residues can be immersed. It was surprisingly found that the pyrolysis residue absorbs up to 140% of its weight when the Verweilzeit is sufficient. In other words, a significant amount of wash water, which may consist of circulating water, partly or wholly separated from the gas washing unit, can be combined by itself. It has also been found that the greater the carbon content in the pyrolysis residue, the greater the absorption of moisture. In addition, for complete benetzung, you need to allow sufficient time for your stay. For example, the immersion operation can be completed by adjusting the speed of the screw conveyor system (Schneckenfordersystem) slowly.

A further refinement of the invention to increase the content of carbon in the pyrolysis residues is that inertstoffe may be used in advance in wastes transported into gas-collecting trommels (north-shaped devices for collecting gas). ) Can also be removed. This can be done, for example, via a sorting device such as a cammmwalzeusortierer. At this time, the pyrolysis residues treated by this method were found to have been unexpectedly found to have an activated carbon structure (Aktivkohlesstruktur) with chemical screening properties. Thus, this residue can be used arbitrarily as activated carbon.

Another advantage of the present invention is that the pyrolysis residue can be entrained in a Filtervorrichtung behind the drying chamber of the gas washing device as a filter of activated carbon.

[Initiation of invention]

The share of sulfur in pyrolysereingas from pyrolysis is determined by, among other things, the sulfur content of the coke used in gas converters. Separation from the pure gas of pyrolysis is very difficult, as is known. Now, when the filter section of the gas washing unit is connected, the binders that are not completely cleaned, for example sulfur or fluorine binders, are absorbed by the activated carbon filter.

At this time, since the residue of pyrolysis is used, almost no additional cost is incurred, and the pyrolysis residue is advantageously used in this way. This also means that the sulfur content in the waste gas is much lower than the specified air-limiting value without incurring any cost, and another advantage in gas converters is that the coke with a relatively high sulfur content is advantageously used. It can be.

The high sorption of pyrolysis residues can be used to remove harmful components from other products if necessary. This can be done by mixing these components with the liquid drawn off from the circulating water. This can be used to remove hazardous substances from other devices, in addition to making the waste almost free of hazardous substances.

Another advantage of the present invention is that by operating the pyrolysegaswerk (Pyrolysegaswerk) processing the waste from the house can be reduced by more than 50%. In addition, one ton of household waste generally results in less than 100 liters of wastewater. This amount of wastewater generally contains hazardous substances, so it is not ecologically desirable to drain it without treatment. However, according to another aspect of the invention, ozone (Ozon) is added to the liquid drawn out from the circulating water of the gas washing apparatus, and after treatment, cyanides (concentration. ≤ 10 g / m 3), and / or phenol If the concentration is 40g / ㎥, the burden of harmful substances can be significantly reduced without any extra cost.

If the pyrolysis residue is treated in this way, the material can enter the Biogas device without any problem. These pyrolysis residues, which normally contain 60% of their own weight, are controlled by the high content of coal and ammonium from gas washes, especially because they are controlled by the degree of burden of waste and cyanide. It is a carrier for anaerobic methangasbildner. This anaerobic methane gas former transforms a group of absorbed substances that can be biologically changed into available gases. Homogenisierung, controlled by ozone, minimizes the risk of excessive amounts and the destruction of the environment. Experiments have shown that short ozoneization is sufficient to achieve this homogenization effect. This ozonation time is generally less than one quarter of the time for complete ozonation.

In order to further reduce the burden of hazardous substances from the waste water, the remaining water (Uberscha βwasser), which is not bound by pyrolysis residues in accordance with another aspect of the present invention, is generally used for the removal of water from the circulating water of the gas Less than 50% by volume. Can be further ozonated. This may be done concurrently with the work in the biogas unit, or may be performed instead. By fully ozonizing the excess water, CSB can be lowered to less than 400 mg of oxygen per liter, BSB to about 60 mg / m 3, and the share of cyanide and phenol typically down to 0.1 g / m 3. However, only some of the most extreme parts of the wastewater have to be divided in this way, as some of the liquids drawn from the circulating water combine to a considerable extent in the pyrolysis residues. Therefore, ozoneization of the rest of the water requires only minimal energy consumption. Therefore, unlike the methods that have been used so far, the problem of separation no longer appears in the case of the present invention.

The pyrolysis residues handled by the process according to the invention can be used in a lime heating oven (Kalkbrandofen) for use in energy supply instead of or in parallel with the biogas system. To do this, it can be pressed into brick-shaped particles. Surprisingly, if some of the inerts were separated before the gas was released, the Heizwert was found to be equal to the burnt value of lignite. This calorific value is sufficient for the dissolution process.

When properly mixed, ceramic or calcification of the inert material part occurs. In this case, especially heavy metals are included.

Experiments have shown that lime or lime ovens can contain calcium-containing compounds, such as those produced from Kalkofen filterstanb, lime hydrate or kalkhydrat, and substances containing sulfur, chlorine, fluorine, heavy metals or coal residues. Fully burned residue (Ausbrand-Reststoff) when mixtures composed of combustion components are compressed to suitable brick-like particles with a vorweilzeit of about 45 to 120 minutes at a temperature of about 1200 ° C and about 400-550 kg / cm 2. It turns out that this appears. At this time, the entire existing chlorine portion, and almost 100% of the sulfur portion and metal, are ceramicized or combined with ash to such an extent that the lye can not be removed. In other words, this means that it is possible to remove harmful substances, especially harmful substances caused by heavy metals, without harming the environment.

The conditions necessary for ceramicizing the metal are only SiO ₂ , CaO, ZnO, Fe ₂ O ₃ and / or MgO with lead, chromium, manganese, cadmium, beryllium, barium, selenium, arsenic, antimony, vanadium, bismuth, It only makes the mole ratio of the entire population of metals, such as strontium and / or Zyrkon, reach 6: 1. The conditions for combining sulfur, chlorine and fluorine compounds are that calcium, magnesium and sodium have a molar ratio of at least 2: 1 relative to sulfur, chlorine and fluorine. These mixtures should then be able to contain water equivalent to 40% of their maximum weight, with a calorific value of at least 100 Kcal / kg. This is to allow, for example, combustion materials in lime ovens to burn under the required residence time and temperature. At this time, the entrained metals are oxidized and taken into the melt of CaO and MgO. In this, they form a relatively inactive ceramic group. Sulfur compounds are absorbed as sulfites or sulfates, and chlorine and fluorine in the liquid phase combine to form calcium chloride (CaCl ₂ ) and fluorite CaF ₂ .

Experiments with pyrolysis residues have shown that this material can play a role in raising the temperature by entrusting the function of combustion components. The harmful constituents absorbed therein-these can also be caused by other factors acting as a pyrolysegaswerk, which can be grouped by mixing into a tank containing pyrolysis residues. -At this time, it is separated and removed so as not to harm the natural environment. Thus, the pyrolysis device leaves no residues that need to be finally stored.

In addition, the amount of reusable energy can be increased by more than 5% by reducing the amount of self-existence required for the ozone system for cleaning gases and improving energy utilization even after the energy demand for the device has been drained. Also turned out.

In the case of biogas systems, the addition of pyrolysis residues reduces the cost of converting waste into heat, thereby improving the economics.

In the case of the present invention, the amount of waste finally needed to be stored is several times less than the waste from general waste incinerators. In addition, the latter is very toxic and must be separated and removed as special waste.

Best Mode for Carrying Out the Invention

An apparatus for carrying out the present invention is shown in the drawings, and the content of the invention is explained in principle.

Since the basic structure is shown in DE-OS 35 29 345, only the important parts of the present invention are drawn in detail. The extraction of pyrolysis residues from the gas-trolling Trommel via spiral screw conveyors is shown in DE-OS 33 47 554 (see in particular Figures 7 and 8). Of course, other carriers may be used in place of the helical device shown. The only condition is that the pyrolysis residues must be sufficiently immersed in the bath at a reasonable time.

The waste passes through the conveyor (1) and into the Vorbrecher (2) which is roughly chopped. The carriage 4 and the conveying groove 3 together with the magnettabscheideeinrichtung 5 transport the waste into the separator 6. In the separating device 6, the vegetable parts as wet heavy wastes are separated, and fall into the container or carrier 7 provided thereunder. At this time, inert materials may also be separated and extracted. The amount of extraction of this inert material is adjusted so that the pyrolysis residue from the gas-collecting trommel has at least 25% of its own weight of carbon. This is to increase the portion of carbon in the thermal decomposition material. The remaining waste debris is transported to the next stage carrier (8), another crusher (Zerkleinerungseinrichtung) (9), and then with a centrifugal force (Hydrozyklon) (10), using a centrifugal force of the current to which the current is connected Passes through the tube (11), once again separated. It is conveyed to a spiral thermocompressor (14) by means of heat. After the tube 11, the waste is conveyed through the tube 12 to the biogas device 13 together with the separated waste from the Behalter 7. Prior to this gas unit, the fluidid separator (Fluidklassifizierer) can be operated to separate heavy inert materials first.

In a spiral thermoschneckenpresse 14, it has a structure in which gas can be easily discharged at about 110 to 150 DEG C by frictional pressing (Reibungspressung) in a known manner. Particles with a size of 50 mm are formed.

Instead of the particle form, it is possible to produce waste components pressed in fluff, ie poorly structured, or pelletized, ie brick-shaped, to a suitable size. In these cases, it takes a relatively long time to extract the gas. Waste components chopped in this way enter the gas harvesting trommel 16 via a Zellenradscheuse 15 or other conveying device. In this, combustion gases (Schwelgas) are produced in a known manner at temperatures between 450 and 650 ° C. This gas passes through a tube 17 and a Staubabscheideeinrichtung 18 into a Hochtemperatur-Gaswandler 19 at high temperature. In the gas converter 19, combustion gas is prepared or converted on a coal bed or a coke bed. Gas converters of this kind are described, for example, in DE-OS 33 17 977.

After passing through the Warmetauscher 20, the gas enters the gas washing apparatus. The device consists essentially of a towering device (Wasserspruhturm) 21, a blower (22), a washing device (23) and a Trofenabscheider (24) which sprays one water. . The gas washed past the gas pipe 25 goes to a gasometer 26. If too much gas is transported, the remaining gas may be transported through another tube 27 to the device 28 therein.

In general, gas flows from gas meter 26 to gas meter 29. The gas meter 29 is connected to the generator 30. At this time, the waste gas burnt through the waste gas pipe 31 enters the chimney 32.

The gas converter 19 obtains water through the pipe 33 and coke through the coke carrier 34. Ash and thick matter are passed out through the conveying pipe (35). In some cases, one of the ways to save energy may be to make a tube 36 for returning the coke to recover the coke from this thick material.

In the gas pipe 25, another pipe 37 branches off. This tube is connected to a gas burner 38. The gas burner serves to supply heat for the gas collecting trommel (16). At the stage of starting the device, an oil burner (Olbrenner) 39, or a separate gas burner, serves to warm the Schweltrommel. However, while the apparatus is still in operation, the heat requirements required for the gas-collecting trommel 16 can be fully covered by the combustor 38 alone.

The washing water generated during the gas washing enters the washing water tank 40, and then into the filter device 41 (usually a removable container). The separated solid matter in the filter device passes through the pipe 42 and into the container 43 which receives the ash. After draining and conveying the pipe 44, the remaining material is transported out of the container 43 receiving the ash and pushed back into the device (Einschubvorrichtung) or, in some cases, the wheeled drainage 15, again to dry liquor trommel. (10) Go inside.

The purified washing water passes from the filter device 41, passes through the pipe 45, passes through the cooling tower 46, and then returns to the spray device 21 of the gas washing device. Some of the clarified wash water enters a wash water neutralizer (Waschwasserneutralisanlage) 47. Steam condensates (Brundendampfkondensat) from the helical thermal compressor 14 also pass through the tube 58 and into the apparatus 47. Unless they are transported past the tubing 65 into a vessel (Vorbehalter) 53 in front of the biogas unit, the wash water from the washing water neutralizer 47 passes through the tubing 78 for spraying. 21) Come inside.

At this time, some of them pass through the pipe 69 from which the portion is drawn out and into the circulating water-conversion processing apparatus (Kreislaufwasser-Chargenbehandlungsanage) 48. In this, washing water is chemically purified-unless the chemical oxidation (Chemikalienoxycation) is replaced by ozonation by appropriate chemicals introduced through the tube (49) in a known manner. This can significantly reduce the addition of additives that leave a lot of debris. Part of the washing water passing through the circulation pipe 50 is passed through the air filter 51, and serves to remove the foaming. At this time, the waste gas is passed through the chimney (52) through the chimney (32). Then, another part of the washing water passes back through the pipe 80 and into the spray apparatus 21 again.

Chemically and mechanically purified water exits the circulating water-conversion treatment plant 48 and passes through a tube 71 into a vessel 53 in front of the biogas unit. Into the vessel 53 may contain mud (Klarschlamm), mixed fertilizer (Rohkompost), or other substances of this kind, if necessary. This is indicated by arrow 54. Vapor condensation past pipe 65 may enter directly into vessel 53 unless it is transported through circulating water-conversion treatment apparatus 48.

Substances made in the biogas device 13 from the vessel 53 enter the hydrolysis step, or into the gas cracker 56. The hydrolysis device 56 is connected to a heat exchanger (Gegenstromwarmetauscher) 57 with flow on the opposite side. The heat exchanger obtains heat through the hot water conveying pipe 62, and the conveying pipe 62 branches off from the cooling tower 46 of the washing and purification apparatus. The heating device in the bottom of the decay chamber (Faulraumboden) 67 serves to control the temperature of the methane zone of the decay chamber to rise between 33 and 37 ° C.

In this way, the remaining heat from the pyrolysis device can be used for the biogas device 13.

The biogas device 13 is usually made in a mixed manner. In the case of making a biogas device in which the phases are separated, a normal acidic phase (Saurephase) can be made into the intermediate shaft 63 in the upper region. In the lower region, on the other hand, an acetic acid is produced. The generated methane gas is drawn out through the methane gas pipe (59), and passed through a buffer (60) and a compressor (61) to the gas pipe (25), or a gas washing device of the pyrolysis device to be washed. Will be The fermented debris is conveyed out by the suction tube 66 and is conveyed to a pre-draining device (Vorentwasserungseinrichtung) 68. This will only contain about 20% or less moisture. That is, the solid matter contained in the fermentation dregs is dried by more than 75%, usually about 85% by the drying press (69). The remaining water contained in the fermentation is collected in a container (Lagune) 70 to collect the contents together with the bottom of the fermentation, and if necessary, is transported to the treatment device 48 or flows directly to the drain.

Substances separated in the circulating water-conversion treatment unit 48 are conveyed through the tube 64 to the purifier.

The pyrolysis residues are conveyed out through the water tank 72 in the gas-collecting trommel apparatus 16. In this case, such a conveying operation may be performed by, for example, a spiral conveying device. The water tank 72 serves to immerse the pyrolysis residues along with the required liquid through a tube 73 carrying a portion of the liquid (Flussingkeitsteilmengenleitung). The tube 73 branches out from the conversion processing apparatus 48 at this time.

In this way, the pyrolysis residues immersed in the liquid are transported to the biogas device 13 after being passed out through the tube or, in some cases, for example, ozonation or other purification. The biogas device 13 is, of course, only discussed in an example form. With regard to the invention itself this is not necessary. Instead of drawing the pyrolysis residues into the biogas device 13, the pyrolysis residues may be conveyed through a tube 74A to a Kalkbrennofen 77 if necessary.

In addition, the pyrolysis residue may be dried and then transported into the filter device 75 as an activated carbon filter through the pipe 74B. The filter device 75 is then located between the gas cleaning device and the gas meter 26. In this case, the activated carbons (Aktivkohle) obtained from the pyrolysis residues should at least have no harmful substances. That is, for this purpose, or instead of supplying dirty or circulated water through the liquid conveying pipe 73, it means that the fresh water is supplied through the pipe 81 for this to the tank.

If necessary, some of the liquid extracted from the circulating water may be treated in an ozone injection unit 76. The ozone device 76 is connected together with the circulating water conversion treatment device 48. A portion of the water drawn from the circulating water through the tube 79 is properly purged in the ozone device 76 before entering the water tank 72 through the tube 73 and in some cases pyrolysis as described in this method. The residue may enter the filter apparatus as an activated carbon filter.

Lime burn oven (77)-Pyrolysis residue is passed through the tube (74A) into this. The above functions and operations are generally well known and will not be described in detail here. At this time, the pyrolysis residue is optionally used as a combustion material together with other combustion components. Of course, it is not necessary that there is a pipe 74A directly connected between the water tank 72 and the lime burning oven 77. In accordance with the teachings of the present invention, not all aggregates necessarily have to be in the same place. Thus, for example, the biogas device 13 and the lime burning oven 77 may be installed at different places. At this time, the transport of the material can then take place in any manner.

A portion of the liquid that is not completely received by the pyrolysis residue in the water tank 72 may, if necessary, be completely ozonated, if necessary, through the ozone device 76 before it enters the purifier.

Of course, the tube 73 carrying a portion of the liquid does not necessarily have to branch off the wash water neutralizer 47. Rather, if necessary, some of the circulating water may be withdrawn from other places in the circulating water pipe. The same applies to the connection of the ozone injection device 76.

Claims (13)

In a method for producing usable gas from waste by pyrolysis, the pre-crushed waste is made into particles or bricks having a size of about 3 to 50 mm, and having at least 75% dryness. It is transported into a heated gastling trommel device (Entgasungstrommel), where Schwelgas is produced, which is separated from the remainder of ash or other constituents, and the dry gas is burned in a gas converter. The combustion gas is separated by gas, which is then washed by circulating and supplied washing water in a subsequent gas washing apparatus, and some of the washing water is removed from the washing water of the gas washing apparatus in water to dilute the harmful component concentration. Pyrolysis residues converted to water and withdrawn from the Schweltrommel for dry distillation The gas is produced by pyrolysis of waste, which is transported through the water tank so that at least a part of the liquid drawn out from the circulating water of the gas washing devices 21 to 24 and 47 to 51 enters into the water tank 72. Way. 2. The inert material according to claim 1, wherein the inert material is first extracted from the waste entering the gas collecting device 16 by a separation operation, and the amount of the inert material extracted is at least 25 parts by weight of the pyrolysis residue from the gas collecting trommel. Method for producing a gas by pyrolysis of waste, characterized in that adjusted to have a carbon corresponding to%. The method for producing gas by pyrolysis of waste according to claim 1, wherein the pyrolysis residue treated by a part of the circulating washing water is introduced into an activated carbon filter. 4. The gas production method according to claim 3, wherein the pyrolysis residue is put into a filter device (35) behind the gas washing device (21 to 24) as an activated carbon filter. The method according to any one of claims 1 to 4, characterized in that it is used to separate harmful substances from other products in the concentrate of the circulating water extracted from the circulating water for washing the residue. Gas production method by pyrolysis of waste to The liquid drawn out from the circulating water of the gas washing apparatus is pretreated by ozone injection, and after the pretreatment, the concentration of cyanide is 10 g / m 3 or less and / or. Or a method of producing gas by pyrolysis of waste, characterized in that the concentration of phenol reaches less than 40 g / m 3. The liquid drawn out from the circulating water of the gas washing apparatus is not absorbed when the pyrolysis residues are immersed, and is subsequently ozonated so that the CSB is 450 mg or less of oxygen (O _2). ) / Liter (L), the gas production method by pyrolysis of waste. The method for producing gas by pyrolysis of waste according to claim 1, wherein the pyrolysis residue immersed in the liquid is introduced into a purification device or a biogas device (13). The method of producing a gas by pyrolysis of waste according to claim 1, wherein the pyrolysis residue immersed in the liquid is introduced into a lime burning oven (77). A degassing device comprising a device for pulverizing waste for carrying out the method according to claim 1, a drying device, a device for letting in pulverized waste and letting out hard pyrolysis residues, and a separation gas. Composed of a combustion gas discharge pipe is connected to the gas converter for producing (Spaltgas), the gas converter is connected to the gas washing device and the device for exporting the pyrolysis residues, and also has a water tank for sending out the pyrolysis residues, And a portion (73) of the liquid from the circulating water conversion treatment device (48) of the gas washing device is transported to the water tank (72). Method according to claim 10, characterized in that a separator (6) is provided in front of said degassing device (16) for removing inert material. 12. The filter device (75) according to claim 10 or 11, characterized in that a filter device (75) is provided at the rear of the gas cleaning devices (21 to 24, 47 to 51) so that pyrolysis residues can enter the activated carbon filter therein. Method for producing gas by pyrolysis of waste. 12. The gas production by pyrolysis of waste according to claim 10 or 11, characterized in that an ozone injection device (76) is provided for pretreatment of the liquid drawn out from the circulating water of the gas washing devices (21 to 24). Way.

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