JP2006124496A - Device and method for thermally co-decomposing coal with biomass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the formation of soot in a thermal decomposition device, becoming the cause of operational troubles on thermally co-decomposing coal with biomass, and improving the yield of gas, tar and char. <P>SOLUTION: This device and method for thermally co-decomposing the coal with biomass is characterized by using a reaction oven of the thermal decomposition device having a structure with two chambers and two stages, wherein the lower stage is a gasifying oven 2 and the upper stage is a thermal decomposition oven 1, blowing carbonaceous raw materials 13 together with oxygen 14, or with oxygen 14 and steam 15 through a gasifying burner 5 into the gasifying oven to cause a partial oxidation reaction for generating a high temperature gas, then introducing the high temperature gas into the thermal decomposition oven 1 and performing the thermally decomposing gasification is characterized by installing a biomass-blowing in nozzle 4 at the lower direction of the coal-blowing nozzle 3, mixing the biomass with the gasified gas and then putting the coal into the oven. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for producing gas, tar, and char by rapidly pyrolyzing and gasifying coal and biomass simultaneously in an air flow layer.

  To date, several coal pyrolysis processes have been proposed that pyrolyze coal at high temperatures to produce hydrocarbon gases such as methane directly and oils such as benzene-toluene-xylene (BTX).

  In Patent Document 1, coal is blown into a high-temperature gas generated by gasification of coal and carbonaceous raw material with oxygen, and rapid heating / pyrolysis reaction of coal is performed in an air flow layer, and in particular, BTX is obtained in a high yield. It is possible to reduce the initial cost of the equipment, and there is shown a high thermal efficiency coal pyrolysis method that does not require heat supply. In Patent Document 1, although the raw material to be pyrolyzed is “coal and carbonaceous raw material”, it does not describe a method of simultaneously pyrolyzing coal and biomass which is one of carbonaceous raw materials. When biomass is pyrolyzed, hydrocarbon gases such as hydrogen, carbon monoxide, and methane, tar, and carbide are generated as in the case of coal pyrolysis.

  In recent years, biomass is being used as a fuel for power generation and the like. However, when the gas obtained by pyrolysis is used for factory fuel or power generation, a large amount of biomass is required. However, there is a problem in collection and handling when using a large amount of biomass, and when the pyrolysis temperature cannot be maintained with only biomass, the problem of biomass collection can be avoided by blowing coal at the same time. Co-pyrolysis is a method aimed at efficiently producing pyrolysis products by thermally decomposing biomass that has a problem in collection at the same time as coal.

  Further, in Patent Document 2, coal particles are introduced into a lower part of a spouted bed gasification furnace having an exhaust heat recovery boiler in the upper stage to generate high-temperature coal-forming gas, and biomass fuel is introduced into the upper part to introduce high-temperature coal gas. Pressurized coal jet that can reduce the occurrence of obstacles caused by ash accumulation and fusion in exhaust heat recovery boilers by reducing the temperature of the high-temperature coal-produced gas generated in the gasifier by bringing it into contact with the coal-produced gas A bed gasification method is disclosed.

Biomass is a collective term for biomass, and according to FAO (United Nations Food and Agriculture Organization), agriculture (wheat straw, sugar cane, rice bran, vegetation, etc.), forestry (paper waste, sawn timber, thinned wood, wood-burning forest) Etc.), livestock (livestock waste), fisheries (fishery processing residue), waste (raw garbage, RDF (refined solid fuel), garden trees, construction waste, sewage sludge), etc. The In this specification, the definition about biomass is based on the said FAO definition. For example, woody biomass refers to forestry biomass in the FAO definition and part of waste biomass, and includes papermaking waste, sawn timber, thinned wood, firewood forest, garden wood, construction waste such as wood, etc. . Woody biomass has a low water content (50 mass% or less) and a high heat generation amount based on moisture, so that gas and solid energy can be efficiently recovered during pyrolysis. Regarding biomass other than woody biomass, basically, if the retained moisture reference calorific value is equal to or higher than the heat of vaporization of moisture + the sensible heat rise of the biomass itself + the heat of decomposition, it can be an effective energy source. Biomass is a carbon neutral material that hardly generates carbon dioxide that affects the global environment during combustion.
JP-A-5-295371 JP 2002-194363 A

  The process proposed in Patent Document 1 is capable of producing BTX and other oils with a high yield, reducing the initial cost of the equipment, and high thermal efficiency coal pyrolysis without heat supply Is the method. In this method, when the high-temperature gasification gas generated from the gasification furnace and the coal put into the pyrolysis furnace are mixed, the temperature of the volatile matter partially generated from the coal may rise too much. . As a result, decomposition of volatile matter has progressed too much, and soot may be generated without becoming a useful oil or hydrocarbon gas. When soot is generated, not only the useful oil and hydrocarbon gas are reduced, but also causes troubles such as adhesion of soot in the pyrolysis furnace and piping and mixing into the generated tar.

  Moreover, the method described in Patent Document 2 blows only biomass into the coal product gas and lowers the gas temperature introduced into the exhaust heat recovery boiler, and the target product is only gas. That is, the method described in Patent Document 2 cannot recover not only gas but also various types of products such as tar and char.

  The object of the present invention is to prevent excessive decomposition of volatile matter generated in a pyrolysis furnace when coal and biomass are pyrolyzed together, and yield of various kinds of products such as gas, tar and char. It is to prevent operational troubles caused by soot.

  In order to solve this problem, the gist of the present invention is as follows.

  (1) In a two-stage coal and biomass co-pyrolysis apparatus in which the lower stage is a gasification furnace and the upper stage is a pyrolysis furnace, a coal blowing nozzle and a biomass blowing nozzle are sequentially arranged on the side wall of the pyrolysis furnace from above. An apparatus for co-pyrolysis of coal and biomass, characterized by being provided.

  (2) Using the coal and biomass co-pyrolysis apparatus according to (1), a carbonaceous raw material is blown together with oxygen or oxygen and water vapor in the gasification furnace to generate gasification gas, and the gasification gas is Introduced into the pyrolysis furnace, the biomass is injected from the biomass blowing nozzle to thermally decompose the biomass, and the coal is injected into the generated mixed gas from the coal blowing nozzle to generate gas, tar and char A method for co-pyrolysis of coal and biomass.

  The “carbonaceous raw material” in the present invention refers to a substance mainly composed of carbon and hydrogen. Examples of the carbonaceous raw material include solid char and liquid tar generated when pyrolyzing coal, petroleum, petroleum residue, petroleum coke, coal, coal coke, biomass, and plastics.

  The co-pyrolysis of biomass and coal is to pyrolyze both biomass and coal in the same reactor. When biomass is pyrolyzed alone, a large amount of biomass is required compared to co-pyrolysis. When using a large amount of biomass, there is a risk of problems in collection and handling. However, by performing co-pyrolysis, it becomes possible to efficiently produce a pyrolysis product by supplementing the shortage of biomass with coal.

  According to the present invention, it is possible to prevent excessive decomposition of volatile components generated in the pyrolysis furnace, increase the calorific value of the generated gas, and increase the yield of gas, tar and char. Furthermore, by reducing the generation of soot, it becomes possible to prevent the soot from adhering in a pyrolysis furnace or piping.

  The present invention is described in detail below. FIG. 1 illustrates a schematic diagram of a coal and biomass co-pyrolysis apparatus according to the present invention, but the shape of the apparatus is not limited to FIG. 1. This apparatus mainly includes a pyrolysis furnace 1 and a gasification furnace 2.

  Since the ash contained in the carbonaceous raw material 13 to be gasified becomes a molten slag 16 at a high temperature of about 1500 ° C., the slag tap 7 and the slag are disposed below the gasification furnace 2 so that the slag 16 can be discharged. It is preferable to provide a water tank 17 for collecting 16.

The gasification furnace 2 is provided with one or a plurality of gasification burners 5 for supplying the finely pulverized carbonaceous raw material 13 together with the oxygen 14 or the oxygen 14 and the water vapor 15. In the gasifier 2, carbon and hydrogen contained in the carbonaceous raw material 13 to be input are converted into CO and H ₂ as much as possible. It is necessary to react with oxygen 14 and water vapor 15 before sooting the volatile matter. For this purpose, the carbonaceous raw material 13, the oxygen 14, and the water vapor 15 into the gasification furnace 2 are blown by the gasification burner 5. Examples of the shape of the gasification burner 5 include a structure in which a carbonaceous raw material 13 flows inside the double tube and oxygen 14 and water vapor 15 flow outside.

  The position of the biomass blowing nozzle 4 into which the biomass 12 is introduced is set lower than the installation position of the coal blowing nozzle 3 in the pyrolysis furnace 1. That is, the throat 6 may be installed between the coal blowing nozzle 3 and the gasification furnace 2, but in order to prevent minute ash contained in the gasification gas 8 from adhering to the furnace wall of the pyrolysis furnace 1. It is preferable to install it around the lower end of the pyrolysis furnace 1 to be removed.

The finely pulverized carbonaceous raw material 13 is blown into the gasification furnace 2 through the gasification burner 5 together with oxygen 14 or oxygen 14 and water vapor 15, and the generated hydrogen, carbon monoxide, carbon dioxide, and water vapor are the main components. The gasified gas 8 is introduced into the pyrolysis furnace 1 directly connected to the gasification furnace 2 through the throat 6. In the present invention, the throat 6 is assumed to be included in the pyrolysis furnace 1. Further, the remaining gas components of the gasification gas 8 are N ₂ and a small amount of by-products.

  The introduced gasified gas 8 is cooled by the biomass 12 introduced from the biomass blowing nozzle 4, while the biomass 12 is pyrolyzed. Finely pulverized coal 11 is introduced from the coal blowing nozzle 3 into the mixed gas 9 generated by the thermal decomposition. The charged coal 11 is heated and pyrolyzed by the mixed gas 9 to generate gas, tar and char, and is discharged as product gas, tar and char 10.

  Here, the temperature of the gasification furnace 2 is generally operated at the melting point or higher of the ash contained in the coal, preferably 1200 to 1700 ° C., considering the reactivity of the coal, the amount of heat dissipated, and the ash melting and discharging performance, Preferably it is 1400-1600 degreeC. Further, the temperature of the pyrolysis furnace 1 excluding the throat 6 to the coal blowing nozzle 3 is determined in consideration of the amount and properties of tar to be generated, the amount and composition of the generated gas, and is preferably 600 ° C to 1100 ° C. The appropriate range varies depending on what kind of product is desired, but 600 to 900 ° C. is more preferable when many tar components are desired, and 1000 to 1100 ° C. is more desirable when many gas components are desired.

  The gasification gas 8 from the gasification furnace 2 is mixed with the biomass 12 having a temperature lower than that of the gasification gas 8 introduced from the biomass blowing nozzle 4, so that the temperature of the resulting mixed gas 9 is changed to the gasification gas 8. It is possible to lower the temperature below. As a result, it is avoided that the high-temperature gasification gas 8 is in direct contact with the coal 11, the reaction between the volatile matter generated from the coal 11 and hydrogen is suppressed, and excessive pyrolysis proceeds. Can be prevented. The biomass 12 contains a larger amount of oxygen atoms than the coal 11, so that the amount of soot generated is small even when it touches the high-temperature gasification gas 8, and a light tar containing a large amount of oil such as BTX is obtained. Can do. BTX is a useful oil frequently used in chemical synthesis.

  The particle sizes of the coal 11 and the carbonaceous raw material 13 used are desirably as small as possible in order to increase the pyrolysis rate by increasing the thermal decomposition rate and to improve the gasification reaction rate. It is preferable that the coal 11 has a particle size of several tens of μm or less that is generally used in pulverized coal combustion because gasification reactivity and yield of thermal decomposition products can be secured. The other carbonaceous raw material 13 is highly reactive in the case of plastics, and thus gasification proceeds even if the particle size is several mm or less. preferable.

  Moreover, although it is preferable that the particle size of the biomass 12 is small, the biomass is highly reactive and even if the particle size is about several mm, the effect of the present invention can be exhibited without any problem. Although not particularly limited, the biomass 12 includes papermaking waste (pulp black liquor, chip dust), sawn wood waste (bark, sawdust, sawdust), forest land residue (branches, leaves, treetops, edge material, low quality material) ), Thinned wood (cedar, cypress, pine) from special forest (waste wood of edible fungi), firewood forest (shii, oak, pine), short-term forestry (willow, poplar, eucalyptus, pine) ) And pruned branches (street trees, garden trees).

  If the temperature after mixing the high-temperature gasification gas 8 and the biomass 12 exceeds 1400 ° C. when mixed with the coal 11, soot may start to be generated, and if the temperature is below 600 ° C., the pyrolysis reaction of coal Is preferably set to 600 ° C. to 1400 ° C. Adjustment of the gas temperature after mixing the high-temperature gasification gas 8 and the biomass 12 is performed by increasing or decreasing the input amount of the biomass 12.

  The charging ratio of the biomass 12 and the coal 11 input to the pyrolysis furnace 1 varies depending on the setting of the outlet temperature of the pyrolysis furnace 1, but the ratio of the biomass 12 in the total amount of the coal 11 and biomass 12 is 20% by mass. It is preferable to set it as -60 mass%. It is preferable in the range of the said mass at the point which can make the temperature of the mixed gas 9 into the temperature which suppresses the generation of soot from the coal 11.

  EXAMPLES Next, although an Example is given and this invention is demonstrated concretely, these Examples do not restrict | limit this invention at all.

  (Embodiment) An embodiment of the present invention under the processing conditions of a coal throughput of 750 kg / h and a biomass throughput of 250 kg / h using the apparatus shown in FIG. In this embodiment, wood chips (water content 15% by mass), which are woody biomass, are used as biomass, and coal is used as a carbonaceous raw material that is gasified in a gasifier.

The gasifier is charged with 500 kg / h coal, 376 Nm ³ / h oxygen, and 30 kg / h steam. The gasifier is operated at a temperature of 1550 ° C. and a pressure of 0.3 MPa, and the coal is partially oxidized to produce hydrogen 16%, CO carbon monoxide 47%, CO ₂ carbon dioxide 13.5%, steam 20%, and A gasified gas of 970 Nm ³ / h containing 3.5% nitrogen was generated. The pyrolysis furnace has a diameter of 45 cm, a height of 7 m, and the coal blowing nozzle is located 0.5 m above the lower end of the straight body of the pyrolysis furnace (not including the throat and the inclined part above it in FIG. 1). The two biomass blowing nozzles are opposed to each other so as to face the lower end of the direct pyrolysis furnace body. The coal used in the gasification furnace and pyrolysis furnace is finely pulverized to a particle size of about 40 μm, and the biomass (wood chips) used in the pyrolysis furnace is crushed to 5 mm or less by nitrogen gas flow transportation. .

  The pyrolysis furnace was charged with 250 kg / h of biomass from the biomass blowing nozzle and 250 kg / h of coal from the coal blowing nozzle.

As a result, the gasified gas, which exceeded 1500 ° C. at the throat, was mixed with the biomass and became a mixed gas, which was reduced to about 1150 ° C. Thereafter, the mixed gas was mixed with coal, the pyrolysis temperature after mixing was 900 ° C., and 1400 Nm ³ / h gas, 235 kg / h char, and 73 kg / h tar were produced at the pyrolysis furnace outlet. The C1-C3 component (light hydrocarbon gas yield) in the product gas was 53 Nm ³ / h in total.

  In addition, no deposits were observed in the pyrolysis furnace due to the generation of soot causing trouble in continuous 200-hour operation.

(Comparative example) The gasification furnace was operated under the same conditions as in the example except that the biomass injection nozzles in the pyrolysis furnace were installed at two positions at the same height as the coal nozzles and perpendicular to the coal injection nozzles. . When the biomass 250 kg / h and coal 250 kg / h are charged into the pyrolysis furnace, the temperature in the pyrolysis furnace becomes 900 ° C., the amount of char produced is 240 kg / h, and the C1-C3 component in the produced gas is 43 Nm ^3. / H. The tar generation amount was 76 kg / h, but the fraction of 350 ° C. or higher in the tar was 30 wt%, and a heavy tar with a low content of useful oil such as BTX compared to 22 wt% in the examples became.

  Further, when the inside of the pyrolysis furnace was examined after continuous operation for 200 hours, adhesion of soot was confirmed.

  Examples and comparative examples are shown in Table 1.

It is the schematic of the co-pyrolysis apparatus of coal and biomass based on this invention.

Explanation of symbols

1 pyrolysis furnace,
2 gasifier,
3 Coal blowing nozzle,
4 Biomass blowing nozzle,
5 Gasification burner,
6 Throat,
7 Slag tap,
8 Gasification gas,
9 mixed gas,
10 product gas, tar and char,
11 Coal,
12 biomass,
13 Carbonaceous raw material,
14 oxygen,
15 water vapor,
16 slag,
17 Aquarium.

Claims (2)

  In the two-stage coal and biomass co-pyrolysis apparatus in which the lower stage is a gasification furnace and the upper stage is a pyrolysis furnace, a coal blowing nozzle and a biomass blowing nozzle are provided in order from the top on the side wall of the pyrolysis furnace. Co-pyrolysis equipment for coal and biomass. Using the coal and biomass co-pyrolysis apparatus according to claim 1,
In the gasification furnace, carbonaceous raw material is blown together with oxygen or oxygen and water vapor to generate gasified gas,
The gasification gas is introduced into the pyrolysis furnace, biomass is introduced from the biomass blowing nozzle to perform pyrolysis of the biomass, coal is introduced from the coal blowing nozzle into the generated mixed gas, gas, A method for co-pyrolysis of coal and biomass characterized by producing tar and char.

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