JP6517704B2 - Gasification furnace - Google Patents

Description

  The present invention relates to a gasifier that oxidizes a raw material such as biomass to generate a product gas.

  In a gasifier that oxidizes a raw material such as biomass to generate a generated gas, the raw material is thermally decomposed to generate a generated gas (for example, carbon monoxide or hydrogen). In the production process of such a product gas, generally, the raw material is carbonized, carbonized char (carbide) is burned, and the burned ash is discharged to the outside. At this time, the raw material is introduced together with an oxidant such as air, or the furnace is heated from the outside.

  Moreover, in such a gasification furnace, tar is generated in the process of generating the product gas. That is, the generated gas contains tar. For example, when the generated gas is burned by a gas engine, the generated tar causes a malfunction of the movable member that contacts the generated gas such as a valve (specifically, an operation failure such that the movable member does not move smoothly due to tar deposition) Inconvenience may occur.

  In order to eliminate such a disadvantage, in the conventional gasifier, the generation of tar is suppressed by setting the oxidizing atmosphere to a temperature that is equal to or higher than a tar pyrolysis temperature necessary for pyrolysis of tar.

  On the other hand, when burning the raw material containing silica (silicon dioxide) at the tar thermal decomposition temperature, if potassium is further contained in the raw material (for example, in the case of raw material such as rice husk), potassium causes crystallization from amorphous silica It is known that crystallization to silica is promoted, which is not preferable.

  Therefore, in the conventional gasifier, it is necessary to suppress the oxidizing atmosphere to a relatively low temperature from the viewpoint of suppressing the formation of crystalline silica, but doing so contradicts with suppressing the generation of tar.

  That is, when the temperature is higher than the temperature necessary for the thermal decomposition of tar to suppress the formation of tar, crystalline silica is formed, while the temperature of the oxidizing atmosphere is relatively low to suppress the formation of crystalline silica. , Can not suppress the occurrence of tar.

  Therefore, the conventional gasifier has the following configuration. That is, it is configured to remove potassium that promotes the formation of crystalline silica by performing acid washing in the pretreatment, or after separating the feedstock into a gas component and a solid component at a temperature at which crystalline silica is not produced in the former step. In the latter stage, multistage oxidation treatment is performed to oxidize only the gaseous component above the tar thermal decomposition temperature to suppress the generation of tar, or as a separate means after the gasification furnace after oxidation at a temperature at which crystalline silica does not form raw materials. It is configured to remove the tar component in the product gas generated by the treatment, or to remove the crystalline silica by post-treatment after oxidation at a temperature above the tar thermal decomposition temperature to suppress generation of tar.

  Thus, in the conventional gasification furnace, in the case where the raw material containing silica and potassium (for example, rice husk) is oxidized to produce the product gas, both the generation of tar and the formation of crystalline silica are suppressed. Requiring multiple steps, such as pre-treatment, dividing the oxidation into multiple steps, or removing the tar or crystalline silica by post-treatment, both the generation of tar and the formation of crystalline silica It is not configured to simultaneously achieve the suppression of

  In this regard, Patent Document 1 discloses a configuration in which an oxidizing agent (air or oxygen) is blown into the oxide layer above the reduction layer where char deposits in a downdraft type gasification furnace (see Patent Document 1) 1). Patent Document 2 discloses a configuration in which an oxidizing agent is blown above a char deposition layer in a fluid bed gasifier (see FIG. 1 of Patent Document 2). Further, Patent Document 3 discloses a configuration in which an oxidizing agent is blown toward a deposited layer of carbide of a biomass material in an updraft type gasification furnace (see FIG. 1 of Patent Document 3).

JP 2005-146188 A JP, 2010-223564, A JP, 2013-213647, A

  However, none of Patent Documents 1 to 3 disclose any configuration for simultaneously achieving both suppression of generation of tar and formation of crystalline silica.

  Therefore, the present invention is a gasification furnace that oxidizes raw materials to produce product gas, and simultaneously achieves both suppression of generation of tar and production of crystalline silica when producing product gas. An object of the present invention is to provide a gasification furnace capable of

  MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research in order to solve the said subject, the present inventors found out the following and completed this invention.

  That is, for the raw material containing silica and potassium (for example, rice husk), the present inventors produce crystalline silica when the temperature of the raw material itself reaches the temperature for producing crystalline silica, which is the temperature for producing crystalline silica. In the gasification furnace that oxidizes the raw materials to produce the product gas by obtaining the knowledge that it is possible to generate the product gas, the predetermined temperature or the predetermined temperature previously determined in the same process (at the same time and in the same space) If the time for exposing the raw material in a range of oxidizing atmosphere is within a predetermined predetermined time range, thermal decomposition of tar proceeds to suppress generation of tar while the temperature of the raw material itself does not rise sufficiently It is possible to suppress the formation of crystalline silica, in other words, heating the raw material under an oxidizing atmosphere above the tar pyrolysis temperature which is the temperature required for the tar to be pyrolyzed. The formation of tar from the time to reach the crystalline silica product temperature or temperature of the crystalline silica product temperature near the been found that can be kept below an acceptable level.

  More specifically, in the gasification furnace where the raw materials are oxidized to generate the generated gas, the present inventors generate the generated gas in the same process (at the same time and in the same space) at the tar thermal decomposition temperature or more. The time to reach the crystalline silica formation temperature, which is the time from the time when the raw material is exposed to the oxidizing atmosphere of temperature to the time when the temperature of the raw material itself reaches the crystalline silica formation temperature, keeps the generation of tar below the allowable level. As a result of conducting an experiment under the hypothesis that the tar generation allowable time which is the time required for the above is exceeded, it has been found that the time to reach the crystalline silica formation temperature becomes equal to or higher than the tar generation allowable time. Thereby, in the same step (at the same time and in the same space), the time for which the raw material is exposed to a predetermined temperature above the tar pyrolysis temperature or an oxidizing atmosphere within a predetermined temperature range is equal to or longer than the tar generation allowable time If it is within a predetermined time range equal to or less than the crystalline silica formation permissible time which is a time for suppressing the formation of silica to the allowable level or less, generation of tar can be suppressed and the formation of crystalline silica can be suppressed.

  In addition, crystalline silica production temperature changes according to the content concentration of potassium, for example, when there is no potassium, while the crystalline silica production temperature is a certain temperature, as the content concentration of potassium increases The crystalline silica formation temperature gradually decreases.

The gasification furnace according to the present invention is based on such findings, and is a gasification furnace that oxidizes a raw material to generate a generated gas, and the predetermined temperature or predetermined temperature at which an oxidation zone for oxidizing the raw material is predetermined. A means for maintaining the range is provided, and a means for passing the raw material through the oxidation zone within a predetermined predetermined time range is provided , wherein the predetermined temperature or the predetermined temperature range is a temperature necessary for the thermal decomposition of tar. It is a temperature above a certain tar thermal decomposition temperature or a temperature range with the temperature as a central temperature, and the predetermined time range is a tar generation allowable time or more, which is a time required to keep tar generation below an allowable level, Or less than the permissible time for forming crystalline silica, which is the time for suppressing the formation of crystalline silica to an acceptable level or less .

In the present invention, the oxidizing atmosphere temperature of the oxidation zone, and the time from when the raw material enters the oxidation zone until the temperature of the raw material reaches the crystalline silica formation temperature which is the temperature at which the crystalline silica is formed. The predetermined temperature or the central temperature of the predetermined temperature range based on the correlation with the time to reach the crystalline silica formation temperature, and the oxidation zone passage time which is the time for the raw material to pass through the oxidation zone within the predetermined time range It is possible to exemplify a mode in which means for determining is provided , and the oxidation area passage time is a time within a range surrounded by the correlation, the oxidation atmosphere temperature, and the tar generation allowable time .

  In the present invention, the correlation can exemplify an aspect corresponding to the equation of the correlation function represented by the following equation [1].

  However, in said Formula [1], T is the said oxidation atmosphere temperature, t is a crystalline silica production | generation permissible time which is the time for suppressing the production | generation of crystalline silica to below an allowable level, and tmin is The tar generation allowable time which is the time required to keep the tar generation below the allowable level, and a, b and c are constants which change depending on the amount of the component of the raw material (in particular, the concentration of potassium contained).

  In the present invention, the correlation can exemplify an aspect corresponding to the correlation table shown in [Table 1] below based on the raw material having a predetermined concentration of potassium.

  However, in said [Table 1], T is said oxidation atmosphere temperature, T1, T2, T3, T4, and T5 are predetermined predetermined values of said oxidation atmosphere temperature, and t is a crystalline silica Crystalline silica formation permissible time which is the time to keep the formation below the acceptable level, and t (K small) is the crystalline silica formation permissible with a raw material less than the potassium content concentration of the raw material to be a reference Represents time, and t (K large) represents an allowable time for the formation of the crystalline silica with a material having a concentration higher than the concentration of potassium contained in the reference material, and A, B, C, D, E Is a set value of the crystalline silica formation allowable time t with respect to the oxidizing atmosphere temperature T, and is a set value that changes according to the amount of components of the raw material (especially the concentration of potassium content). To curb A tar occurs allowed time tmin above setting value is a main time.

  In the present invention, an embodiment can be exemplified in which a means for preheating the inside of the furnace to the predetermined temperature or the predetermined temperature range is provided prior to introducing the raw material.

  According to the present invention, it is possible to simultaneously achieve both suppression of generation of tar and formation of crystalline silica.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the whole structure of the gasification apparatus provided with the gasification furnace which concerns on embodiment of this invention. It is a schematic side view which makes a part of gasification furnace shown in FIG. 1 a fracture | rupture state, and is a figure which shows the state which oxidizes and gasifies a raw material. It is an explanatory view for explaining an oxidation zone, and is a figure expanding and showing near a boundary between a combustion gas layer and a char layer in a furnace shown in FIG. 2, (a) is a char layer with an oxidant FIG. 7 is a view showing an example in which the top of the char layer is set so as not to contact or to be in contact with the surface, and (b) is a position where the inside of the char layer is in contact with an oxidant; It is a figure which shows the example which set the top part of the char layer so that it may be located. It is a graph which shows the diffraction pattern by the X ray diffraction of the silica in the ash obtained with the gasification furnace concerning this embodiment using rice husk as a raw material in comparison with the case of crystalline silica, and (a) is a char It is a figure which shows the result of having performed the top part of a layer in the position which shows in Drawing 3 (a), and (b) shows the result of performing the top part of a char layer in the position which shows in Drawing 3 (b). It is a graph which shows the relationship between crystalline silica production | generation temperature and the content density | concentration of potassium. It is a graph which shows the correlation of the oxidation atmosphere temperature and crystalline silica production | generation time attainment time which were obtained as a result of conducting experiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

[Gasification equipment]
First, an overall configuration of a gasification apparatus 100 (gasification system) provided with a gasification furnace 102 according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration view showing an entire configuration of a gasification apparatus 100 provided with a gasification furnace 102 according to an embodiment of the present invention.

  As shown in FIG. 1, the gasifier 100 includes a storage hopper 101, a gasification furnace 102, a bag filter 103, a gas cooler 104, a scrubber 105, a circulating water tank 106 (water storage tank), and a cooling tower. 107, a gas filter 108, an induction blower 109, a pretreatment unit 110, a next process device (in this example, a gas engine 111, more specifically, a gas engine power generator) which is a device of the next step, and a water seal A tank 112 and an excess gas burner 113 (flare stack) are provided.

  The storage hopper 101 stores the raw material F of the generated gas (fuel gas G in this example). Here, as a raw material, the raw material containing a silica and potassium can be illustrated, For example, non-edible agricultural products, such as rice husks, such as rice and wheat, and rice husks, can be mentioned. In this example, the raw material is a biomass of rice husk containing silica and potassium, and the fuel gas G is a biogas. Thus, the gasifier 100 is a biogasifier.

  The gasification furnace 102 is provided with a raw material introducing portion 102a for introducing the raw material F stored in the storage hopper 101, and a single furnace 102b for producing the fuel gas G from the raw material F introduced at the raw material introducing portion 102a. ing.

  The raw material introduction part 102a is equipped with the raw material introduction conveyor 102a1 and the raw material introduction feeder 102a2 in this example. The raw material introduction conveyor 102a1 conveys the raw material F stored in the storage hopper 101 to the raw material introduction feeder 102a2. The raw material introduction feeder 102a2 introduces the raw material F conveyed by the raw material introduction conveyor 102a1 into the furnace 102b. The gasification furnace 102 will be described in detail later.

  The bag filter 103 removes unnecessary substances such as soot contained in the fuel gas G generated in the gasification furnace 102.

  The gas cooler 104 is provided in a fuel gas supply path from the gasification furnace 102 to the gas engine 111. The gas cooler 104 cleans the fuel gas G from which unwanted matter has been removed by the bag filter 103 with the washing water WW and further cools it with the cooling water CW. The scrubber 105 is further cleaned by submerging the fuel gas G which has been cleaned and cooled in the gas cooler 104 in the cleaning water WW.

  The circulating water tank 106 stores wash water WW supplied to the gas cooler 104 and the scrubber 105. The cooling tower 107 stores cooling water CW supplied to the gas cooler 104.

  The gas filter 108 removes unnecessary substances such as tar contained in the fuel gas G cleaned by the scrubber 105 by filtration. The induction blower 109 sucks the fuel gas G in the fuel gas supply path on the gasification furnace 102 side and discharges it to the fuel gas supply path on the gas engine 111 side and the fuel gas supply path on the excess gas combustion device 113 side.

  The pre-processing unit 110 removes impurities in the fuel gas G discharged to the fuel gas supply path on the gas engine 111 side by the induction blower 109. The gas engine 111 burns the fuel gas G from which the impurities have been removed by the pretreatment unit 110.

  The water seal tank 112 controls the pressure of the fuel gas G discharged to the fuel gas supply path on the gas engine 111 side by the induction blower 109. The surplus gas combustion device 113 burns surplus fuel gas SG which has not been supplied to the gas engine 111 and flows in when the pressure of the fuel gas G exceeds the pressure of the water sealing tank 112.

  In the gasifier 100 described above, the raw material F containing silica and potassium (in this example, rice husk) is introduced into the gasification furnace 102 in the raw material introduction part 102a, and the combustible fuel gas G is generated in the gasification furnace 102. Be done. The fuel gas G generated in the gasification furnace 102 flows in the order of the bag filter 103, the gas cooler 104, the scrubber 105, the gas filter 108, and the induction blower 109, and the gas engine 111 side and the surplus gas downstream of the induction blower 109. Branching to the combustion device 113 side and flowing, the surplus fuel gas SG is burned by the surplus gas combustion device 113, and the fuel gas G is burned by the gas engine 111.

  Specifically, the raw material F is stored in the storage hopper 101, and the raw material F in the storage hopper 101 is introduced into the gasification furnace 102 by the raw material introduction conveyor 102a1 and the raw material introduction feeder 102a2 in the raw material introduction unit 102a.

  In the gasification furnace 102, the raw material F is incompletely burned to generate the fuel gas G. The fuel gas G generated by the gasification furnace 102 is introduced into the bag filter 103 through the gas pipe 201. Here, the fuel gas G is a fuel gas mainly composed of carbon monoxide, and the fuel gas G contains unnecessary substances such as soot and tar (tar below the allowable level generated in the gasification furnace 102), dust and the like. It is included.

  In the bag filter 103, unnecessary substances such as soot contained in the fuel gas G are removed by a filter called a filter cloth. The fuel gas G from which unnecessary substances such as soot and the like have been removed by the bag filter 103 is introduced into the gas cooler 104 through the gas pipe 202.

  A gas pipe (not shown) through which the fuel gas G flows is provided in the gas cooler 104, and the fuel gas G in the gas pipe is cleaned with the washing water WW and cooling water flowing around the gas pipe. It is cooled by CW. The fuel gas G cleaned and cooled by the gas cooler 104 is introduced into the scrubber 105 through the gas pipe 203.

  The cooling water CW supplied to the gas cooler 104 is stored in the cooling tower 107, and the cooling water CW in the cooling tower 107 is introduced into the gas cooler 104 via the water distribution pipe 204. The coolant CW in the water distribution pipe 204 is pressure-fed to the gas cooler 104 by the pump 205, and the fuel gas G is cooled by the gas cooler 104. The cooling water CW obtained by cooling the fuel gas G is discharged to the cooling tower 107 through the water distribution pipe 206.

  Cleaning water WW is stored in the scrubber 105, and the fuel gas G is cleaned by diving in the cleaning water WW in the scrubber 105. The fuel gas G cleaned by the scrubber 105 is introduced into the gas filter 108 through the gas pipe 207.

  Washing water WW supplied to the gas cooler 104 and the scrubber 105 is stored in the circulating water tank 106. The wash water WW in the circulating water tank 106 is introduced into the gas cooler 104 through the water distribution pipe 209 and is introduced into the scrubber 105 through the water distribution pipe 210 branched from the water distribution pipe 209. The wash water WW in the water distribution pipes 209 and 210 is pressure-fed to the gas cooler 104 side and the scrubber 105 side by the pump 211, and the fuel gas G is cleaned by the gas cooler 104 and the scrubber 105. The cleaning water WW whose fuel gas G has been cleaned by the gas cooler 104 is drawn out to the circulating water tank 106 through the water distribution pipe 212, while the cleaning water WW whose fuel gas G has been cleaned by the scrubber 105 is circulated through the water distribution pipe 213. It is led out to the water tank 106.

  In the gas filter 108, unnecessary substances such as tar contained in the fuel gas G are removed by filtration. The fuel gas G from which unnecessary substances such as tar have been removed by the gas filter 108 is introduced into the induction blower 109 through the gas pipe 214.

  In the induction blower 109, the fuel gas G sucked from the fuel gas supply path on the upstream side of the induction blower 109 is discharged to the fuel gas supply path on the downstream side of the induction blower 109. That is, since the fuel gas supply path on the upstream side of the induction blower 109 has a negative pressure, and the fuel gas supply path on the downstream side of the induction blower 109 has a positive pressure, the fuel gas supply path on the upstream side of the induction blower 109 The fuel gas G is attracted to the fuel gas supply path on the downstream side by the inducer blower 109.

  The fuel gas G induced by the induction blower 109 is introduced into the gas engine 111 via the gas supply pipe 215 and the pretreatment unit 110 provided in the gas supply pipe 215. The fuel gas G from which the impurities have been removed by the pretreatment unit 110 is supplied to the gas engine 111. In this example, the gas engine 111 includes a power generation device (not shown) driven by a gas engine unit (not shown), generates electric power by the power generation device, and supplies the exhaust heat of the gas engine portion with hot water supply, air conditioning, etc. It is considered to be a cogeneration system used for

  On the other hand, surplus fuel gas SG not supplied to the gas engine 111 among the fuel gas G generated in the gasification furnace 102 is supplied from the gas supply pipe 215 for supplying the fuel gas G from the induction blower 109 to the gas engine 111 side. It is introduced into the surplus gas combustion device 113 through the surplus gas supply pipe 216 which branches and the water seal tank 112 provided in the surplus gas supply pipe 216.

  The excess gas supply pipe 216 is provided on the upstream side of the water seal tank 112 and connects the induction blower 109 and the water seal tank 112, and the downstream gas supply pipe 216a is provided on the downstream side of the water seal tank 112. The downstream side gas supply pipe 216 b connecting the sealing tank 112 and the surplus gas combustion device 113 is provided.

  Water is sealed in the water sealing tank 112 to a predetermined water level. The water seal tank 112 exerts water pressure on the surplus fuel gas SG discharged from the upstream side gas supply pipe 216 a, whereby surplus fuel gas in the downstream gas supply pipe 216 b from the water seal tank 112 to the surplus gas combustion device 113 Control the supply of SG. Thus, the water sealing tank 112 can control the pressure of the fuel gas G in the gas supply pipe 215.

  In the surplus gas combustion device 113, the surplus fuel gas SG sent via the upstream gas supply pipe 216a, the water seal tank 112, and the downstream gas supply pipe 216b is burned in the surplus gas combustion unit 113a.

  Next, the gasification furnace 102 will be described below with reference to FIGS. 2 and 3.

[Gasification furnace]
The gasification furnace 102 according to the present embodiment is a gasification furnace that oxidizes the raw material F to generate the fuel gas G.

  FIG. 2 is a schematic side view showing a part of the gasification furnace 102 shown in FIG. 1 in a broken state, showing a state in which the raw material F is oxidized and gasified.

  In the gasification furnace 102, the raw material F is thermally decomposed to generate a fuel gas G (for example, carbon monoxide or hydrogen). In the process of producing the fuel gas G, the raw material F is carbonized, the carbonized char R (carbide) is burned, and the burned ash S is discharged to the outside. In this example, the raw material F is introduced together with an oxidant H such as air.

  The gasification furnace 102 is provided with a raw material introducing portion 102a for introducing a raw material F, an oxidant introducing portion 102d for introducing an oxidizing agent H, and a fuel gas outlet portion 102e for causing a fuel gas G to flow out.

The raw material introducing portion 102 a is provided above the uppermost portion δxa of a predetermined assumed char layer δx (in this example, the assumed char deposited layer). The oxidizing agent introducing portion 102 d is provided below the opening 102 ah (in this example, the raw material dropping portion) in the raw material introducing portion 102 a. The fuel gas outlet 102 e is provided above the opening 102 dh in the oxidant inlet 102 d.

  Specifically, the raw material introducing portion 102a is provided on the top surface 102b1 (upper surface) of the furnace 102b. In addition, the raw material introducing | transducing part 102a may be provided in the side part 102b2 upper part of the furnace 102b.

  The gasification furnace 102 further includes a preheating unit 102c (in this example, a temperature raising burner) for preheating the inside of the furnace 102b, and a discharge unit 102f for discharging the ash S and moving the char R downward.

  The preheating unit 102c is a temperature raising burner that performs preheating using combustion of fossil fuel such as propane gas. The preheating unit 102c is provided with a gas supply unit 102c1 provided on the side surface 102b2 of the furnace 102b, and a gas cylinder 102c2 connected to the gas supply unit 102c1 to supply a flammable gas g (in this example, propane gas) to the gas supply unit 102c1. Is equipped. Thus, the preheating unit 102c can preheat the inside of the furnace 102b by the combustion of the flammable gas g supplied from the gas cylinder 102c2 through the gas supply unit 102c1.

  The oxidant introducing unit 102 d is provided on the side surface 102 b 2 of the furnace 102 b. The opening 102 dh in the oxidizing agent introducing portion 102 d is formed such that the introducing direction of the oxidizing agent H is along the horizontal direction, substantially horizontal direction, or upward (for example, obliquely upward).

  The fuel gas outlet 102e is provided on the top surface 102b1 of the furnace 102b. The fuel gas outlet 102e may be provided above the side surface 102b2 of the furnace 102b.

  The discharge part 102 f is provided on the bottom surface 102 b 3 (lower surface) of the furnace 102 b. The discharge unit 102 f includes an ash discharge conveyor 102 f 1 that discharges the ash S flowing out of the furnace 102 b to the outside.

  By the way, in the conventional gasification furnace, as described above, crystalline silica is formed when the temperature is higher than the temperature necessary for the thermal decomposition of tar to suppress the generation of tar, while the formation of crystalline silica is generated. If the oxidizing atmosphere is made relatively low temperature to suppress the generation of tar can not be suppressed.

  In this respect, in the operation method of the gasification furnace 102 according to the present embodiment, the raw material F is previously determined in the oxidation area α while maintaining the oxidation area α for oxidizing the raw material F in a predetermined temperature or a predetermined temperature range. And let it pass within a predetermined time range. In the gasification furnace 102 according to the present embodiment, the first means for maintaining the oxidation area α for oxidizing the raw material F in a predetermined temperature or a predetermined temperature range, and the predetermined time in which the raw material F is predetermined for the oxidation area α And second means for passing through the range. In other words, in the present embodiment, the temperature of the raw material F itself is crystalline silica at the time when the raw material F is heated in an oxidizing atmosphere above the tar thermal decomposition temperature which is a temperature necessary for the thermal decomposition of tar. The generation of tar is suppressed to an allowable level or less by the time it reaches the temperature for forming crystalline silica or the temperature near the temperature for forming crystalline silica.

  Here, "maintaining at a predetermined temperature" is a concept including not only maintaining a constant temperature but also maintaining a substantially constant temperature. Further, as the oxidizing agent H, a gas containing oxygen (typically air) can be exemplified. The oxidant H may be pure or nearly pure oxygen, but in this example is air. In addition, “passing the raw material F to the oxidation zone α” is a concept including passing the char R to the oxidation zone α. The “temperature near crystalline silica formation temperature” is a temperature at which the formation of crystalline silica can be made equal to or lower than the allowable level even if the temperature is exceeded.

  In this example, after passing the raw material F to the oxidation zone α within a predetermined time, the gasification furnace 102 is adjacent to the oxidation zone α at a predetermined temperature of the oxidation zone α or a central temperature or a lower limit temperature of a predetermined temperature range. The low temperature zone β is also reached at a low temperature (specifically, a temperature below the temperature at which crystalline silica is formed). In addition, after passing the raw material F to low temperature area | region (beta), the gasification furnace 102 may be made to reach the oxidation area | region (alpha).

  Specifically, the first means includes an oxidant introducing portion 102d. The second means includes the raw material introduction part 102a and the discharge part 102f.

  The amount of oxidizing agent H introduced from the oxidizing agent introducing portion 102d per unit time is maintained at a predetermined temperature or in a predetermined temperature range in the furnace 102b at the amount of introduction of the raw material F set in advance and the amount of discharge of the ash S set in advance. As described above, it is set to a predetermined value which is determined in advance by a previously conducted experiment or the like.

  The introduction amount of the raw material F per unit time from the raw material introduction part 102a, and the discharge amount per unit time of the ash S from the discharge part 102f, that is, char layer δ (in this example, char deposit layer where char R is deposited) The movement distance per unit time of the char R in is set to a predetermined value which is determined in advance so that the oxidation zone passage time tp, which is the time for the raw material F to pass through the oxidation zone α, falls within a predetermined time range.

  Here, the oxidation zone passing time tp is a time from when the raw material F is introduced and rushes into the oxidation zone α until it leaves the oxidation zone α, and in this example, it is introduced into the furnace 102b from the oxidant introducing portion 102d. It also includes the time for the raw material F to fall freely until it reaches the char layer δ. The falling distance of the raw material F from the raw material introducing portion 102a may be set so that the oxidation region passing time tp falls within a predetermined time range.

  Further, the oxidation zone α is not limited thereto, but can be, for example, a range from the opening 102 dh for introducing the oxidizing agent H to the outlet 102 eh of the fuel gas G.

  In FIG. 2, the control device 102 g and the thermocouples 102 h and the like which are not described will be described later.

  FIG. 3 is an explanatory view for explaining the oxidation region α and is an enlarged view showing the vicinity of the boundary between the combustion gas layer γ and the char layer δ in the furnace 102b shown in FIG. FIG. 3A shows an example in which the top portion δa of the char layer δ is set such that the char layer δ is not in contact with the oxidizing agent H or located in contact with the surface. FIG. 3B shows an example in which the top portion δa of the char layer δ is set so that the inside of the char layer δ is located at a position where the inside of the char layer δ comes in contact with the oxidizing agent H.

  Here, the position where the char layer δ is brought into contact with the oxidizing agent H and the surface of the top portion δa (see FIG. 3A) is a position where the oxidizing agent H is introduced toward the surface of the char layer δ. Further, the position where the inside of the char layer δ is brought into contact with the oxidizing agent H (see FIG. 3B) is the position where the oxidizing agent H is introduced toward the side of the char layer δ.

  The position of the top portion δa of the char layer δ is the amount of introduction of the raw material F from the material introduction portion 102a and the amount of discharge of the ash S from the discharge portion 102f, that is, the movement distance per unit time of the char R in the char layer δ It can adjust by adjusting. For example, the position of the top portion δa of the char layer δ is raised by adjusting in advance the predetermined introduction amount of the raw material F and the predetermined discharge amount of the ash S in which the position of the top portion δa of the char layer δ is maintained constant or substantially constant. Sometimes, the material F is brought into a predetermined introduction amount after the predetermined introduction amount of the raw material F is increased by a distance to be increased more than the predetermined discharge amount of the ash S or the predetermined discharge amount of the ash S is smaller than the predetermined introduction amount. Alternatively, when lowering the position of the top portion δa of the char layer δ while returning the ash S to a predetermined discharge amount, the predetermined introduction amount of the raw material F is made smaller than the predetermined discharge amount of the ash S by a distance to be lowered An embodiment can be exemplified in which the raw material F is returned to the predetermined introduction amount or the ash S is returned to the predetermined discharge amount after the operation is performed with the discharge amount being made larger than the predetermined introduction amount.

  As shown in FIG. 3, the oxidation zone α is not only the zone of the combustion gas layer γ (see FIGS. 3 (a) and 3 (b)) but also the char layer δ (char deposit layer or char fluid bed, this example In the case where the char deposited layer is present and exposed to the oxidizing agent H, the region of the char layer δ also includes the region exposed to the oxidizing agent H (see FIG. 3B).

  In the gasification furnace 102 described above, first, the inside of the furnace 102b is preheated to a predetermined temperature or a predetermined temperature range by the preheating unit 102c to form the oxidation region α in advance. Here, the predetermined temperature or the predetermined temperature range is a temperature or a temperature range that is equal to or higher than the thermal decomposition temperature of the raw material F. Next, when the raw material introduction part 102a is operated to introduce the raw material F from the raw material introduction part 102a, the raw material F is thermally decomposed. Further, the oxidizing agent introducing unit 102 d is operated to introduce the oxidizing agent H from the oxidizing agent introducing unit 102 d. Then, the oxidation zone α is maintained at a predetermined temperature or a predetermined temperature range, and the raw material F is allowed to pass through the oxidation zone α within a predetermined time range. At this time, the raw material F is carbonized, the carbonized char R (carbide) is burned, and the burned ash S is discharged to the outside by the discharge part 102f, while the generated fuel gas G is made to flow out from the fuel gas outflow part 102e.

  According to the present embodiment, the oxidation zone α for oxidizing the raw material F is maintained at a predetermined temperature or a predetermined temperature range, and the raw material F is allowed to pass through the oxidation zone α within a predetermined time range. Since the generation of tar is suppressed to the allowable level or less until the temperature of the raw material F itself reaches the temperature for forming the crystalline silica or the temperature for forming the crystalline silica after heating the raw material F under the oxidizing atmosphere above the temperature. When the fuel gas G is produced using a raw material (for example, rice husk) containing silica and potassium as the raw material F, the raw material is produced in the same process (at the same time and at the same space) in an oxidizing atmosphere at a predetermined temperature or a predetermined temperature range. Even if F is oxidized, the inventors of the present invention can suppress the generation of tar and the formation of crystalline silica as long as the oxidation zone transit time tp is within the predetermined time range. It is possible to realize a gasifier based on the new knowledge of As a result, when generating the fuel gas G, it is possible to simultaneously simultaneously suppress the generation of tar and the generation of crystalline silica.

  Next, it was confirmed whether or not both generation of tar and formation of crystalline silica could be suppressed, which will be described below.

  FIG. 4 is a graph showing X-ray diffraction patterns of silica in the ash S obtained by the gasification furnace 102 according to the present embodiment using rice husk as a raw material F in comparison with the case of crystalline silica. FIG. 4 (a) shows the result of performing the top δa of the char layer δ at the position shown in FIG. 3 (a), and FIG. 4 (b) shows the top δa of the char layer δ as FIG. 3 (b) The results are shown at the position shown in FIG. In FIG. 4, the solid line represents the X-ray diffraction pattern of silica generated by the gasification furnace 102 according to the present embodiment, and the broken line represents the X-ray diffraction pattern of crystalline silica. .

  The X-ray diffractometer analyzes the diffraction resulting from scattering and interference of X-rays by electrons around the atoms of the sample when the sample is irradiated with X-rays. Therefore, if the silica is amorphous, X-rays are scattered and interfered to form a gentle diffraction pattern, and if crystalline silica, the X-rays are reflected at a certain diffraction angle to have a sharp peak. It becomes a diffraction pattern.

  As shown in FIG. 4, the silica in the ash S obtained by the gasification furnace 102 according to the present embodiment has a position where the top portion δa of the char layer δ is shown in FIG. 3A (see FIG. 4A) And at any position shown in FIG. 3 (b) (see FIG. 4 (b)), it is amorphous, and the crystalline silica is confirmed by the diffraction pattern by X-ray diffraction. I could not.

  Also, as a result of quantitative analysis of crystalline silica, it was found to be below the allowable level.

  On the other hand, it was found that tar in the fuel gas G obtained by the gasification furnace 102 according to the present embodiment using rice husk as the raw material F is also below the allowable level. Moreover, the fuel gas generated in the gasification furnace 102 according to the present embodiment using rice husk as the raw material F can be used without problems in the next step (for example, the gas engine 111), and the heat amount required for the next step ( For example, it has been found that the heat amount necessary to operate the gas engine 111 is included.

  In addition, as already stated, crystalline silica production | generation temperature changes according to the content density | concentration of potassium.

  FIG. 5 is a graph showing the relationship between the crystalline silica formation temperature Tc and the potassium concentration Kc.

  As shown in FIG. 5, for example, in the absence of potassium, the crystalline silica formation temperature Tc is Tx ° C., while the crystalline silica formation temperature Tc gradually increases as the potassium content concentration Kc increases. It will decline.

  Specifically, in the gasification furnace 102 and the method of operating the gasification furnace 102 according to the present embodiment, the predetermined temperature or the predetermined temperature range is a temperature equal to or higher than the tar pyrolysis temperature or a temperature range where the temperature is a central temperature. . In addition, the predetermined time range is crystalline silica, which is longer than the allowable tar generation time which is the time required to keep tar generation below the allowable level, and is the time to suppress the generation of crystalline silica to the allowable level or less. It is less than the generation allowable time.

  According to the present embodiment, the fuel gas G is produced using the raw material F (for example, rice husk) containing silica and potassium as the raw material, in the same process (at the same time and in the same space), at the tar thermal decomposition temperature or more. If the time for which the raw material F is exposed to an oxidizing atmosphere at a predetermined temperature or in a predetermined temperature range is within the predetermined time range which is equal to or longer than the tar generation allowable time and equal to or lower than the crystalline silica generation allowable time, tar generation is reliably suppressed. As a result, the formation of crystalline silica can be reliably suppressed.

  Here, the tar generation allowable time is a time in which no tar is generated, or even if tar is generated, an amount of generation that can be tolerated is allowed. The acceptable level of tar is that the level of tar can be practically acceptable, and if tar is removed in a later step (for example, an apparatus such as scrubber 105), the tar after removed in a later step A level can be made into the level which does not have trouble in practical use. Further, the crystalline silica formation allowable time is a time at which the crystalline silica is not formed or the amount of formation that can be tolerated even if the crystalline silica is formed. The acceptable level of crystalline silica can be a defined level taking into account the effect of crystalline silica.

  In addition, when the raw material F passes through the oxidation zone α (during passage), the gasification furnace 102 has a predetermined amount of heat necessary for the next step (in this example, necessary for operating the gas engine 111) May generate a fuel gas of at least a predetermined heat amount, or may generate a fuel gas of a predetermined heat amount at a low temperature range β before and / or after the raw material F passes through the oxidation zone α. It may be

[Correlation between oxidation atmosphere temperature and time to reach crystalline silica formation temperature]
In the operation method of the gasification furnace 102 according to the present embodiment, the temperature of the raw material F itself reaches the crystalline silica formation temperature Tc from the time when the raw material F enters the oxidation zone α and the oxidation atmosphere temperature T in the oxidation zone α. Oxidation between the predetermined temperature or the central temperature of the predetermined temperature range and the predetermined time range based on the correlation と with the crystalline silica formation temperature reaching time tc which is the time to the end The area transit time tp is determined. The gasification furnace 102 according to the present embodiment has a predetermined temperature or a central temperature within a predetermined temperature range and an oxidation region within a predetermined time range based on the correlation ρ between the oxidizing atmosphere temperature T and the crystalline silica formation temperature reaching time tc. It further comprises a third means for determining the transit time tp.

  The third means controls the operation of the first means (specifically, the oxidizing agent introduction portion 102d) and the second means (specifically, the raw material introduction portion 102a and the discharge portion 102f).

  More specifically, the gasification furnace 102 controls the entire gasification furnace 102 (see FIG. 2), and a temperature detection means (thermocouple 102h in this example) for detecting the temperature of the oxidation zone α in the furnace 102b. And). The third means constitutes a part of control means of the control device 102g. The thermocouple 102 h is provided in the oxidation region α.

  The control device 102g includes a processing unit 102g1 (see FIG. 2) including a microcomputer such as a CPU (Central Processing Unit), a nonvolatile memory such as a ROM (Read Only Memory), and a volatile memory such as a RAM (Randam Access Memory) And a storage unit 102g2 (see FIG. 2) including the above, and has a timer function.

  The control unit 102g performs operation control of various components by causing the processing unit 102g1 to load and execute a control program stored in advance in the ROM of the storage unit 102g2 onto the RAM of the storage unit 102g2. .

  The control device 102g controls the operation of the raw material introduction unit 102a to adjust the introduction amount of the raw material F per unit time from the raw material introduction unit 102a (specifically, the transport speed of the raw material introduction conveyor 102a1). The control device 102 g controls the operation of the oxidizing agent introducing unit 102 d to adjust the introduction amount of the oxidizing agent H per unit time from the oxidizing agent introducing unit 102 d. In addition, the control device 102g controls the operation of the discharge unit 102f to discharge the ash S per unit time from the discharge unit 102f (specifically, the conveyance speed of the ash discharge conveyor 102f1), that is, the char R in the char layer δ. Adjust the downward moving distance per unit time. The thermocouple 102 h transmits an electrical signal regarding the detected temperature of the oxidation zone α to the controller 102 g. The controller 102 g detects (recognizes) the temperature of the oxidation zone α by an electrical signal related to the temperature of the oxidation zone α.

  Then, the control device 102g is configured to pass the oxidation zone passing time within a predetermined time range by the introduction amount of the raw material F per unit time from the raw material introduction unit 102a and the discharge amount per unit time of the ash S from the discharge unit 102f. tp can be set.

  According to the present embodiment, even if the oxidation zone passage time tp is changed within a predetermined temperature or a predetermined temperature range or / or within a predetermined time range, the oxidation atmosphere temperature T and the time to reach the crystalline silica generation temperature tc Using the correlation ρ of the oxidation zone α at a predetermined temperature or a predetermined temperature range corresponding to the oxidation atmosphere temperature T, and / or an oxidation zone passing time tp within a predetermined time range corresponding to the crystalline silica formation temperature reaching time tc. Can be changed easily (for example, automatically or manually, in this example, automatically by a control operation by the controller 102g).

(Expression of correlation function)
According to the findings of the present inventors, when the oxidizing atmosphere temperature T is lower than the crystalline silica formation temperature Tc, no crystalline silica is formed, and the crystalline silica formation temperature reaching time tc becomes theoretically infinite. On the other hand, the time to reach the crystalline silica formation temperature tc does not practically become 0 minutes. Then, from the graph of the experimental results (see FIG. 6), the correlation ρ between the oxidizing atmosphere temperature T and the time to reach the temperature at which the crystalline silica is generated can be regarded as inversely proportional.

  FIG. 6 is a graph showing the correlation ρ between the oxidation atmosphere temperature T and the time to reach the temperature of the formation of crystalline silica, obtained as a result of the experiment.

  As shown in FIG. 6, the correlation ρ between the oxidizing atmosphere temperature T and the crystalline silica formation temperature arrival time tc can be made to correspond to the equation κ of the correlation function shown by the following equation [1].

  However, in the formula [1], T is the oxidizing atmosphere temperature, t is the crystalline silica formation allowable time, tmin is the tar generation allowable time, and a, b and c are components of the raw material F It is a constant that changes with the amount (especially the concentration of potassium).

  Here, the constants a, b, c, d are values that can be calculated by experiments and / or simulations performed in advance, and depend on the amount of components of the raw material F (for example, rice husk), particularly the content concentration of potassium.

  The constants a, b, c, d can be obtained by solving four simultaneous equations obtained by substituting the values of (T, t) of four points obtained by experiments etc. into the equation [1]. .

  The equation κ of the correlation function indicating the correlation ρ between the oxidizing atmosphere temperature T and the crystalline silica formation temperature arrival time tc is stored in advance in the storage unit 102g2.

  The control device 102 g can detect (recognize) the crystalline silica generation temperature arrival time tc from the oxidizing atmosphere temperature T. As a result, the control device 102 g can set the predetermined time range (the oxidation region passage time tp) corresponding to the oxidizing atmosphere temperature T to a range surrounded by hatching shown in FIG. On the other hand, the control device 102 g can detect (recognize) the oxidizing atmosphere temperature T from the crystalline silica generation temperature reaching time tc. As a result, the control device 102g can set the predetermined temperature or the central temperature (oxidizing atmosphere temperature T) in the predetermined temperature range according to the crystalline silica generation temperature arrival time tc to a range surrounded by hatching shown in FIG.

  Then, the control device 102 g can control the predetermined time range or / and the predetermined temperature or the predetermined temperature range so as to satisfy the relationship of the formula [1]. In addition, the operator can set the predetermined time range or / or the predetermined temperature or the predetermined temperature range so as to satisfy the relationship of equation [1].

  According to this configuration, the control configuration for setting the predetermined time range or / and the predetermined temperature or the predetermined temperature range can be easily and easily realized by using the expression κ of the correlation function.

(Correlation table)
In addition, the correlation と between the oxidizing atmosphere temperature T and the time to reach the crystalline silica formation temperature tc corresponds to the correlation table shown in the following [Table 1] based on the raw material F having a predetermined concentration of potassium. Can.

  However, in [Table 1], T is the oxidizing atmosphere temperature, T1, T2, T3, T4, and T5 are predetermined values determined in advance of the oxidizing atmosphere temperature T, and t is the crystalline silica formation allowable time. And t (K small) represents the allowable time for crystalline silica formation in the raw material F which is less than the potassium content concentration of the reference raw material F, and t (K large) is the standard raw material F Represents the allowable time t for forming crystalline silica in the raw material F, which is higher than the concentration of potassium contained in A, B, C, D and E are set values of the allowable time t for forming crystalline silica with respect to the oxidizing atmosphere temperature T It is a setting value which changes with the amount of ingredients (especially concentration of content of potassium) of materials F, and is a setting value more than tar generation allowable time tmin. T1, T2, T3, T4, and T5 satisfy the relationship of T1 <T2 <T3 <T4 <T5, and A, B, C, D, and E satisfy the relationship of A> B> C> D> E. Fulfill.

  Here, the set values A, B, C, D, and E are values that can be set by experiments and / or simulations performed in advance, and the component amount of the raw material F (for example, rice husk) (especially the content concentration of potassium) Depends on

  A correlation table showing the correlation ρ between the oxidizing atmosphere temperature T and the crystalline silica formation temperature arrival time tc is stored in advance in the storage unit 102g2.

  Then, the control device 102g can control the predetermined time range or / and the predetermined temperature or the predetermined temperature range so as to satisfy the relationship of [Table 1]. In addition, the operator can set the predetermined time range or / or the predetermined temperature or the predetermined temperature range so as to satisfy the relationship of [Table 1].

  According to this configuration, by using the correlation table, the control configuration for setting the predetermined time range or / and the predetermined temperature or the predetermined temperature range can be easily and easily realized.

(Setting of correlation)
In the present embodiment, the correlation ρ is set or updated at the time of installation of the gasification furnace 102 or at the time of determination of the procurement site of the raw material F or change.

  In the present embodiment, the correlation ρ is measured for the raw material F at the installation place of the gasification furnace 102 or the procurement place of the raw material F, or with respect to the raw material F having various component amounts (in particular, the concentration of potassium). Experiments to obtain the correlation に 対 す る of the amounts of various components with respect to the raw material F, and the amount of the component of the raw material F at the installation place of the gasification furnace 102 or the source of the raw material F ), And from the various correlations 〜 to 取得 obtained in advance by experiments etc. according to the component amount of the obtained raw material F (especially the content concentration of potassium) the installation place of the gasification furnace 102 or the procurement of the raw material F Select the correlation 適用 to be applied to the raw material F on the ground, and generate tar according to the amount of components of the raw material F (especially the concentration of potassium) at the installation site of the gasification furnace 102 or the Suppression of both formation of crystalline silica Can be adjusted simultaneously with the oxidation atmosphere temperature T of the oxidation zone α and the oxidation zone transit time tp of the raw material F. Note that various correlations ρ to で き る can be set (stored) in the storage unit 102 g 2 in advance.

[About preheating]
In the operation method of the gasification furnace 102 according to the sixth embodiment, the inside of the furnace 102b is preheated to a predetermined temperature or a predetermined temperature range before introducing the raw material F. The gasification furnace 102 according to the present embodiment further includes a fourth means for preheating the inside of the furnace 102b to a predetermined temperature or a predetermined temperature range prior to the introduction of the raw material F. Specifically, the fourth means includes a preheating unit 102c.

  According to this configuration, the gasification process can be performed quickly by preheating (preheating) the inside of the furnace 102b to a predetermined temperature or a predetermined temperature range prior to introducing the raw material F.

  In the gasification furnace 102 according to the present embodiment, the controller 102g is configured to maintain the temperature of the oxidation zone α at a predetermined temperature or to fall within a predetermined temperature range according to the detected temperature from the thermocouple 102h. The introduction amount of the raw material F from the raw material introduction portion 102a per unit time, the introduction amount of the oxidizing agent H from the oxidant introduction portion 102d per unit time, the discharge amount of ash S from the discharge portion 102f per unit time, That is, at least one of the downward moving distances of the char R per unit time in the char layer δ may be adjusted.

  The present invention is not limited to the embodiments described above, and can be implemented in other various forms. Therefore, such an embodiment is merely illustrative in every point and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of the claims, and is not limited at all by the text of the specification. Furthermore, all variations and modifications that fall within the equivalent scope of the claims fall within the scope of the present invention.

100 Gasifier 101 Storage hopper 102 Gasification furnace 102a Raw material introduction part 102a1 Raw material introduction conveyor 102a2 Raw material introduction feeder 102ah Opening 102b Furnace 102b1 Top surface 102b2 Side surface 102b3 Bottom surface 102c Preheating part 102c1 Gas supply part 102c2 Gas cylinder 102d Oxidant introduction part 102dh Opening opening 102e fuel gas outlet 102eh outlet 102f outlet 102f1 ash discharge conveyor 102g controller 102g1 processor 102g2 memory 102h thermocouple 103 bug filter 104 gas cooler 105 scrubber 106 circulation water tank 107 cooling tower 108 gas filter 109 inducement blower 110 Processing unit 111 Gas engine 112 Water seal tank 113 Excess gas burner 113a Excess gas burner A to E Set value F Raw material G Fuel H H Oxidizer Kc Concentration R Char S Ash T Oxidation atmosphere temperature Tc Crystalline silica formation temperature a to d Constant g Flammable gas t Crystalline silica formation allowance time tc Crystalline silica formation temperature reaching time tmin Tar formation allowance time tp Oxidized zone transit time α Oxidized zone β Low temperature zone γ Combustion gas layer δ Char layer δa Top δx Assumed char layer δxa Top κ Correlation function equation 相関 Correlation

Claims (5)

A gasifier that oxidizes raw materials to produce product gas,
There is provided means for maintaining an oxidation zone for oxidizing the raw material at a predetermined temperature or a predetermined temperature range, and means for passing the raw material to the oxidation zone within a predetermined time range is provided .
The predetermined temperature or the predetermined temperature range is a temperature higher than or equal to a tar thermal decomposition temperature which is a temperature necessary for thermal decomposition of tar, or a temperature range in which the temperature is a central temperature,
The predetermined time range is a time to keep the formation of crystalline silica at or below an acceptable level, or more, which is a time required to suppress the occurrence of tar to be at or below an acceptable level. A gasification furnace characterized by being less than an allowable time . The gasifier according to claim 1 , wherein
Crystalline silica which is an oxidation atmosphere temperature of the oxidation zone, and a time from when the raw material enters the oxidation zone to a temperature at which crystalline silica is generated which is the temperature at which the raw material itself produces crystalline silica Means for determining an oxidation zone transit time which is a time during which the raw material passes the oxidation zone within the predetermined temperature or the predetermined temperature range based on the correlation with the generation temperature reaching time provided,
A gasification furnace characterized in that the oxidation area passage time is a time within a range surrounded by the correlation, the oxidation atmosphere temperature and the tar generation allowable time . The gasification furnace according to claim 2 , wherein
The said correlation respond | corresponds to the type | formula of the correlation function shown by the following formula [1], The gasification furnace characterized by the above-mentioned.

However, in said Formula [1], T is the said oxidation atmosphere temperature, t is a crystalline silica production | generation permissible time which is the time for suppressing the production | generation of crystalline silica to below an allowable level, and tmin is The tar generation allowable time which is the time required to keep the tar generation below the allowable level, and a, b and c are constants which change depending on the amount of components of the raw material. The gasification furnace according to claim 2 , wherein
The said correlation respond | corresponds to the correlation table shown by the following [Table 1] on the basis of the said raw material of predetermined content concentration of potassium, The gasification furnace characterized by the above-mentioned.

However, in said [Table 1], T is said oxidation atmosphere temperature, T1, T2, T3, T4, and T5 are predetermined predetermined values of said oxidation atmosphere temperature, and t is a crystalline silica Crystalline silica formation permissible time which is the time to keep the formation below the acceptable level, and t (K small) is the crystalline silica formation permissible with a raw material less than the potassium content concentration of the raw material to be a reference Represents time, and t (K large) represents an allowable time for the formation of the crystalline silica with a material having a concentration higher than the concentration of potassium contained in the reference material, and A, B, C, D, E Is a set value of the crystalline silica formation allowable time t with respect to the oxidizing atmosphere temperature T, and is a set value that changes according to the amount of components of the raw material, and is a time required to suppress tar generation below an allowable level Some tar outbreak Content is the time tmin more than the set value. The gasifier according to any one of claims 1 to 4 , wherein
A gasification furnace characterized in that means for preheating the inside of the furnace to the predetermined temperature or the predetermined temperature range is provided prior to introducing the raw material.

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