CN102076830A - Two-stage high-temperature preheating steam gasifier - Google Patents

Abstract

A gasifier is disclosed incorporating two reactors using externally generated preheated high temperature steam injected into the first reactor, wherein the heating requirement for gasification is provided by the sensible heat of the steam. The gasifier may produce syngas of medium and high LCV. The first reactor is a fixed bed gasification stage that gasifies the coarse feed and the second reactor is an entrained flow gasification stage that gasifies the liquid and fine feed. The solid raw feed is devolatilized in a first fixed bed reactor of the gasifier with the aid of high-temperature steam and subsequently subjected to a higher temperature in a second reactor sufficient to crack and destroy tars and oils. Activated carbon may be formed as a by-product. The gasifier may use a variety of solid and liquid feeds. The gasifier is capable of gasifying these different feeds simultaneously.

Description

Two-stage high-temperature preheating steam gasifier

field of invention

The present invention relates generally to two-stage high temperature steam gasifiers for the production of synthesis gas and optionally activated carbon from coarse carbonaceous feedstocks, and more particularly to the ability to simultaneously gasify coarse solid carbonaceous feedstocks and fine solid carbonaceous feedstocks. feedstock or liquid carbonaceous feedstock. The present invention also relates to a process for the gasification of crude carbonaceous feedstock to produce synthesis gas and optionally activated carbon using a two-stage gasifier having two reactors, wherein no oxygen is fed to the first-stage reactor, only Preheated steam is fed with a temperature of at least 700°C.

Background of the invention

Gasification is the conversion of solid feedstocks such as solid coal, petroleum coke, biomass and/or solid waste, liquid feedstocks such as black liquid oil or gaseous feedstocks using reactants such as air, steam and oxygen, alone or in any combination, Converted into fuel gas mainly composed of hydrogen (H ₂ ) and carbon monoxide (CO), containing a small amount of carbon dioxide (CO ₂ ), water (H ₂ O), methane (CH ₄ ), higher hydrocarbons and nitrogen (N ₂ ) High temperature thermal decomposition process.

The thermal gasification process is a highly endothermic chemical reaction. A common method for supplying heat to the gasification is one of: a) an external heat source, such as the sensible heat of hot coke (char) recirculation, and/or the sensible heat of a heated gasification agent, b) partial heating heat of reaction for oxidation of feedstock (input carbonaceous material), and c) exothermic heat of reaction of non-carbonaceous materials such as quicklime with _CO2 .

References to partial combustion of input carbonaceous materials have been widely adopted. When using this technology, non-flammable gas CO ₂ is produced and since it is not removed, dilute syngas is formed and the LCV (low calorific value, a measure of the combustion value of dry gas substances) of the resulting syngas is limited . Furthermore, the presence of _CO2 from partial combustion (oxidation) leads to small partial pressures of other gaseous species, which is detrimental to other valuable gasification reactions, such as, for example, the water gas shift reaction. Thus, the hydrogen content in the synthesis gas is negatively affected.

The idea of using sensible heat to supplement the main energy required for the gasification process has been considered recently and has shown positive results. For example, US 2004/0060236 A1 teaches an economical small-scale gasification system for the gasification of solid fuels to pyrolysis gas, wherein a heated mixture of steam and air is introduced into a reformer together with the pyrolysis gas, Produce reformed high-temperature crude gas. The mixture of air and steam is preferably heated to at least 300°C, and more preferably at least 400°C. Any type of heat exchanger or heater can be used as the air/steam heating means for heating the air and steam mixture.

US 6,837,910 teaches an apparatus and method for gasifying liquid or solid fuels, wherein a hot mixture of steam and air is introduced into at least one of a thermal decomposition zone of said solid or liquid fuel and a reforming zone of thermal decomposition gases within. The mixture of air and steam is heated to a temperature of at least 700°C, and more preferably above 800°C.

Other known systems using high temperature air/steam/oxygen up to 1000°C for biomass/waste gasification processes have also been applied (Lucas C., Szewczyk D., Blasiak W., Mochida S., High Temperature Air and Steam Gasification of Densified Biofuels, Biomass and Bioenergy, Vol.27, No.6, December 2004, pages563-575). Ponzio Anna, Yang Weihong, Lucas, C, Blasiak W. proposed in Development of a Thermal Homogenous Gasifier System using High Temperature Agent, CLEAN AIR-International Journal on Energy for aClean Environment., Vol.7, No.4., 2007 Coke-free hydrogen-rich gas, wherein the process uses only steam at a temperature of 1000° C. and is carried out at atmospheric pressure of about 1 atm.

In US 2003/0233788 A1 a method for gasification of carbonaceous material to fuel gas is disclosed. It includes a superheated steam (USS) composition comprising primarily water vapor, carbon dioxide and its highly reactive free radicals having a formation temperature of about 1316°C to about 2760°C. The USS composition, including the high temperature flame, is contacted with carbonaceous material causing rapid gasification/reforming. The USS is formed by burning a substantially ash-free fuel with "artificial air" comprising enhanced oxygen and water vapor, wherein the "artificial air" is at least about 60 mole percent. The oxygen/fuel ratio must be controlled so that no soot is formed. Enhanced use of oxygen in the process can significantly increase the operating costs of the process.

According to US 2003/0233788A1, steam-only gasification has been studied and commercially used from about 1950-1960. However, problems associated with steam-only gasification methods include low achievable reaction temperatures, typically below about 815 °C, where long residence times and high energy consumption dominate due to the limited heat in steam.

All of the above prior art uses only one stage reactor, either fixed bed or fluidized bed gasifier.

It is also known that thermal conversion of biomass/waste/coal can be understood as comprising two main highly endothermic stages: removal of volatiles and conversion of coke, respectively. Previous studies have shown that 90% of the volatile content of the total weight of biomass is released instantaneously if heated above 600 °C. The second stage is coke conversion. To obtain coke-free ash, ie 100% coke conversion, much higher temperatures are required for thermal conversion of coke. Typically, this temperature should be above 1000°C, depending on the melting point of the ash.

The fixed bed gasifier type is widely used in small scale energy generation (<10 MW _th ) because of its very simple construction and operation. It has been found that if the design of a gasification fixed bed reactor follows the above two stages, it becomes more efficient in many ways.

There is considerable work to be done on this mode of operation of fixed bed gasifiers. Typically, secondary air is injected into the gasifier. For example, Pan et al. (Y.G.Pan, X.Roca, E.Velo and L.Puigjaner in Removal of tar by secondary air injection in fluidized bedgasification of re-sidual biomass and coal, Fuel 78(1999)(14), pp.1703 -1709) reported a reduction of 88.7 wt.% tar by injecting secondary air just above the point of biomass feed in a fluidized bed at a temperature of 840-880°C.

Narv et al. (Biomass gasification with air in an atmospheric bubbling fluidized bed.Effect of six operational variables on the quality of produced raw gas, Industrial and Engineering Chemistry Research 35(1996)(7), pp.2110-2120) in fluidized bed gasification Injection of secondary air was carried out in the free space of the vessel and a temperature rise of about 70°C was observed which resulted in a reduction of tar from 28 to 16 g/ ^Nm3 .

The Asian Institute of Technology (AIT) in Thailand has transformed the biomass gasifier, which can obtain a fuel gas with a tar yield of about 50mg/Nm ³ , which is about 40 times lower than that of a reactor under similar operating conditions (TAMilne and RJEvans, Biomass Gasification "Tars": Their Nature, Formation and Conversion. NREL, Golden, CO, USA, Report No. NREL/TP-570-25357 (1998)). This concept employs a downdraft gasifier with a secondary air intake. The tar produced during biomass pyrolysis passes through the high temperature residual coke bed at the bottom and decomposes at high temperature.

Bhattacharya et al. reported a similar gasifier in A study on wood gasification for low-tar gasproduction, Energy 24 (1999), pp. 285-296, in which the coke produced inside the gasifier itself acts as a filter to further extract The tar yield was significantly reduced to 19 mg/Nm ³ , and the CO and H ₂ concentrations in the fuel gas were higher.

Cao et al reported the study of a two-zone fluidized bed reactor in A novel biomass air gasification process for producing tar-free higher heating value fuel gas, Fuel Processing Technology 87 (2006) 343-353. In this study, auxiliary fuel gas and secondary air streams were injected into the upper region of the reactor to reduce tar composition. The test results show a calorific value of about 5MJ/Nm ³ .

US 6,960,234 discloses a multi-faceted gasifier and related methods. The gasifier combines a fixed-bed gasification section and an entrained-bed gasification section. Activated carbon can be formed in the upper fixed bed section and entrained bed section.

US 6,647,903 discloses a method and apparatus for the generation and utilization of combustible gases using a gasifier comprising a first and a second reaction stage, wherein an oxidizing gas is injected into both stages. The invention operates in a manner that enhances tar decomposition while forming output fuel gas products _H2 and CO. In addition, part of methane may also be formed. In certain modes of operation, activated carbon may be produced.

JP 6256775 discloses a two-stage complete gasification method for organic substances used in methane synthesis, wherein the organic substances are gasified in the presence of steam and oxygen in the first stage gasification process, and the gaseous substances are not gasified in the second stage gasification process. The reacted substances and tar gases are gasified at a higher temperature than in the first stage gasification process. A gasifier comprising two stages is also disclosed. In order to prevent the flow of solid carbonaceous material from the first stage gasification process to the second stage gasification process, the channel between the two stages can be narrowed or a filter can be placed between the two stages. The gasifier includes two inputs for oxygen and steam, one in the first stage and the other in the second stage.

In the above studies, the purpose of the secondary air/oxygen and/fuel injection was to increase the temperature in the free space to decompose the tar and improve the steam reforming reaction. However, the injection of secondary air will not only increase the content of diluent, especially nitrogen, but also reduce the content of combustibles produced by gasification. This results in a drop in the LCV of the generated fuel gas. Furthermore, the injection of secondary air makes it difficult to control the composition of the generated gas.

The aforementioned US 6,960,234 also states that fixed bed gasification requires crude fuel typically 1/4"-2" in diameter, and that limiting technical features of fixed bed gasification include: tars and oils being carried over by syngas; difficulty in using coal/fuel fines , because they block the void space between the crude fuel in the fixed bed; and it is difficult to use liquid hydrocarbon feeds.

In order to be able to produce combustible gases with medium and higher low calorific value (LCV), and simultaneously gasify solid and liquid/fine feeds, as well as produce other additional valuable substances such as activated carbon, this paper presents a new fixed-bed gasification device. Such a gasifier is as described in claim 1 . Also disclosed and claimed is the use of a two-stage gasifier having two reactors for the gasification of crude carbonaceous feedstock to produce synthesis gas, optionally activated carbon, wherein no oxygen is fed to the first-stage reactor , but only preheated steam with a temperature of at least 700 °C is fed. The method is described in claim 4 .

Contents of the invention

Therefore, for the two-stage gasifier of the prior art, for example, the two-stage gasifier disclosed in JP 6256775 and recorded in the preamble of claim 1 includes: equipped with an inlet for crude carbonaceous feed and for a first reactor with a first inlet for steam; and a second reactor equipped with a second inlet for steam, optionally together with air or oxygen; and an outlet for synthesis gas; wherein the first and The second reactor is separated by a narrow section of reduced cross-section for restricting the flow of unreacted solid carbonaceous material from the first reactor to the second reactor, wherein the first reactor capable of operating at a temperature of at least 600°C, and wherein said second reactor is capable of operating at a higher temperature, the above object is achieved by means of the technical features of the characterizing part of said claim, according to which said second reactor The reactor is a lower reactor, the first reactor is an upper reactor, a grid is arranged at the bottom end of the first reactor, and the first inlet for steam is set adjacent to the first reactor bottom, so that preheated steam at a temperature of at least 700° C. can be fed via said inlet from below said grid into said first reactor equipped with an outlet for synthesis gas, The second reactor is provided with an inlet for a fine solid carbonaceous feed and/or a liquid carbonaceous feed, the second inlet for steam is located adjacent to the bottom of the second reactor, thereby enabling feeding preheated steam at a temperature of at least 700° C., optionally together with preheated air or oxygen at the same temperature, into the second reactor via the inlet from below, and in the second reactor The bottom end of is provided with a second narrow portion having a reduced cross-section.

Accordingly, in one aspect the invention relates to a two-stage gasifier as described above.

In the gasifier of the present invention, solid coarse material and solid fine and/or liquid material can be gasified simultaneously. Carbonaceous coarse material is fed into the first reactor and carbonaceous (waste) liquid and/or carbonaceous fine solid material is fed into the second reactor.

In a further preferred embodiment of said two-stage gasifier, one or more and preferably all inlets for steam, air, oxygen and carbonaceous (waste) liquid and/or carbonaceous fine solid material are located at Corresponding portions of the gasifier enter tangentially into the gasifier, these portions having a circular inner cross-section.

In a further preferred embodiment of said two-stage gasifier, the inlet for carbonaceous (waste) liquid and/or carbonaceous fine solid material comprises at least two The most distantly distributed entrance.

In another aspect of the invention, it involves the use of a two-stage gasifier having two reactors, a first and a second reactor, respectively, to gasify a crude carbonaceous feed to produce synthesis gas and optionally activated carbon Methods. Such a process is described in claim 4 and comprises the steps of: (a) feeding a crude carbonaceous feed to the first stage reactor of the gasifier; (b) operating the reactor at a temperature of at least 600°C gasification of the carbonaceous feed is effected by contacting the crude carbonaceous feed with steam in a first stage reactor in which no oxygen is fed to the first stage reactor and only preheated steam having a temperature of at least 700°C is fed, and the process further comprises a step (c), wherein any solid and/or liquid carbonaceous material obtained in step (b) is subjected to a temperature of at least 700°C Contact with preheated steam, optionally with air or oxygen, within the operating second stage reactor to obtain any combination of the following products: activated carbon; CO; CO ₂ , and heat of combustion.

In a preferred embodiment, the process comprises a further step (d), wherein a fine solid carbonaceous and/or liquid carbonaceous feed is simultaneously fed to the second stage reactor of the gasifier. Thus, in this embodiment, the gasifier may be fed both a coarse feed and a fine solid and/or liquid carbonaceous feed.

In another preferred embodiment of the process, the second stage reactor is also fed with externally generated preheated steam having a temperature of at least 700°C. With this embodiment, the internal combustion in the gasifier, also called partial combustion or oxidation, can be kept to a minimum, since the required energy is provided externally. Thus, in this embodiment no gas or oxygen supply is required for internal combustion heat generation. Also, the yield of activated carbon can be maximized when no air or oxygen is fed to the second reactor.

In a further preferred embodiment of the process, the second reactor is fed with air (ie in addition to said high temperature steam). With this embodiment, a very high quality synthesis gas can be obtained, since carbon is also converted to CO and not only activated carbon. And, depending on the steam/air ratio, internal combustion (ie production of _CO2 ) can still be avoided. At the same time, the ratio of CO: activated carbon can also be controlled by controlling the steam/air ratio.

In a further preferred embodiment of the method, pure oxygen (instead of air) is used. In this embodiment, the method can be used for industrial purposes. At the same time, the need for by-product separation is minimized and undesired dilution effects on gaseous products are kept to a minimum.

Other embodiments and advantages are apparent with reference to the detailed description and claims.

The terms "internal combustion", "partial combustion" and "partial oxidation" are used interchangeably to refer to the combustion that occurs within the gasifier.

Description of drawings

Figure 1 shows a system flow diagram generally illustrating the gasification process of the present invention for biomass and solid waste.

FIG. 2 shows a cross-sectional view of an embodiment of a gasifier 21 .

Figure 3 is a top view of the gasifier of the present invention showing tangential liquid feed injection through inlets 19a and 19b.

Detailed ways

The gasifier of the present invention combines two reactors, using externally generated preheated high-temperature steam injected into the first reactor, wherein the heating requirement for gasification is provided by the sensible heat of this steam. The gasifier can produce medium and higher LCV syngas. The first reactor is a fixed bed gasification section for gasification of coarse feed, while the second reactor is an entrained bed gasification section for gasification of liquid and fine feed. The solid crude feed is devolatilized in the first fixed bed reactor of the gasifier by means of high temperature steam and then subjected to higher temperatures sufficient to crack and destroy tars and oils in the second reactor .

Activated carbon may be formed as a by-product. The gasifier can use various solid and liquid feeds. The gasifier is capable of gasifying these different feeds simultaneously.

As shown in Figure 1, the idea of the present invention is to divide the gasifier 21 into two sections: the first upper section 3 is used for the removal of volatile components, and the first section only uses the high-temperature preheated pure steam generated externally (preferably 700 °C-1000°C), and the second lower stage 4 is used for thermal conversion of coke, which uses air and steam, oxygen and steam, or only steam at high temperature (preferably 700°C-1600°C, more preferably 800°C-1200°C) Heat the mixture. Reactor 3 comprises a fixed bed with grid 8 .

In the first reactor 3 , the energy for the volatile component removal process is provided jointly by the sensible heat of the steam fed into the first reactor through the inlet 7 and the hot stream from the second reactor through the narrow section 20 . The temperature in the first reactor is controlled at a level of at least 600°C by the amount and temperature of steam fed into the reactor.

In the first reactor 3 , high temperature steam is mixed with the coarse feed (biomass) 1 entering via inlet 2 . When the biomass is heated by high-temperature steam, the volatile component removal process proceeds as follows:

At the same time, due to the presence of steam, the steam reacts with the volatile components:

CO+ _H2O → _CO2 + _H2 (3)

The small amount of oxygen released by the pyrolysis process (which takes place in the first reactor and also in the second reactor when a liquid and/or solid fine feed is injected) and the second reactor 4 reacts according to the equation :

C _m H _n +(m/2+n/4)O ₂ →mCO+n/2H ₂ O (4)

CO+ ¹ / ₂ O ₂ →CO ₂ (5)

H ₂ + ¹ / ₂ O ₂ →H ₂ O (6)

CO+ _H2O → _CO2 + _H2 (7)

Since the reactor temperature in the first stage reactor 3 is controlled at a level of at least 600° C., and the residence time is also controlled, and the gas in the first reactor is in a very oxygen-deficient environment, in the first reactor Any solid and/or liquid coke produced in the reactor will not react with any oxidant in the reactor. Thus, any solid and/or liquid coke will fall into the second reactor 4 by gravity.

In the second reactor 4, the energy for the coke conversion process is preferably provided by the sensible heat of the steam and air mixture and from the partial oxidation of the coke. In order to achieve coke-free conversion, the temperature in the second reactor should be above the melting point of the ash to allow the ash to form a slag. Typically, for woody biomass, the ash can have a melting point of 1300°C. The reactor 4 comprises an entrained bed with a grid 5 .

When no other feed (liquid and fine particles) is injected, the main reactions are:

gasification:

C+O ₂ ＝＞CO ₂ -393.5kJ/mol(8)

C+H ₂ O＝＞CO+H ₂ +131.3kJ/mol(6)

C+2H ₂ O＝＞CO ₂ +H ₂ +90.2kJ/mol(10)

- Partial oxidation:

C+0.5O ₂ ＝＞CO-110.5kJ/mol(11)

- Boudouard reaction:

C+CO ₂ ＝＞2CO-172.4kJ/mol(12)

-Water gas conversion:

CO+H ₂ O=>CO ₂ +H ₂ -41.1kJ/mol(13)

- Methanation:

CO+3H ₂ ＝＞CH ₄ +H ₂ O-206.1kJ/mol(14)

-hydrogenation:

C+2H ₂ ＝＞CH ₄ -75kJ/mol(15)

All reactions (1)-(15) occur when the second feed (liquid and fine particles) is injected into the second reactor.

Many reactions occur simultaneously, and it is difficult to precisely control the process as shown here. However, by careful selection of process parameters (temperature, residence time, and oxygen/steam ratio) in the present invention, it is possible to maximize certain desired products, such as activated carbon and syngas.

In addition, activated carbon can be processed as a by-product of the thermal conversion of carbon-based materials via the present invention. Generally, the preparation of activated carbon in the prior art includes two steps: carbonization of the raw material under high temperature (500-1000°C) oxygen-free conditions to remove the maximum amount of oxygen and hydrogen elements, and at a higher temperature, in the Carbonization products are activated in the presence of oxidizing gases such as water, carbon dioxide, or both. The activation should be performed under sufficiently controlled conditions to achieve the desired transformation.

In the present invention, the feed is first gasified in the first reactor 3 by high temperature pure steam (level of at least 600° C.), followed by carbon activation preferably in the second reactor 4 by high temperature steam.

In the present invention, roughly as shown in Fig. 1, high temperature steam and optionally air or oxygen (over 700°C) are mainly obtained by using a honeycomb regenerative heat exchanger such as eg EP0607921 or co-pending described in PCT/SE2009/050019, the relevant contents of these publications are hereby incorporated by reference.

FIG. 2 shows a cross-sectional view of the gasifier 21 . Carbonaceous feed 1 is at the top of the gasifier, enters via feed inlet 2, and travels down through first reactor 3, then through grid 8, then into second reactor 4, through grid 5 until it turns to molten ash at the bottom 6. The feed can include biomass, coal, municipal solid waste, or any combination thereof. The particle size of the coarse carbonaceous feed 1 is generally 0.5 cm to 1.8 cm, preferably 0.5 cm to 1.2 cm.

In the first reactor 3 , the feed is heated by a combination of sensible heat carried by high temperature steam (over 700° C.) and flue gas produced by coke oxidation and gasification in the second reactor 4 . High temperature steam carried by line 7 for feed gasification in the first reactor enters narrow section or throat 20 via port (or ports) 11 . The amount of high temperature steam added at port 7 is set to maintain the temperature at point 3 (first reactor) between 600-900°C, and preferably above 700°C. At a point near 8 (grid), when air or oxygen is fed into the second reactor, a hot combustion flame may occur because the excess oxygen combusts the pyrolysis gas released from feed 1 and forms a further Any liquid and/or fine solids feed to the second reactor.

The temperature in reactor 3 is controlled by the temperature and flow of steam injected from point 7, and the temperature and amount of excess oxygen from reactor 4. The residence time of the feed 1 in the reactor 3 is mainly controlled by the gaps of the grid 8 .

In order to achieve good mixing between the gasification agent (steam) and the feed 1 a throat 20 is provided. The diameter of the throat 20 is generally smaller than the diameter of the reactor 3 hearth. The slope of the tapered portion 14 should preferably be about 45-60°. The diameter of the steam injection port 11 should preferably be 2-3 times smaller than the diameter of the throat 20 .

After the crude carbonaceous feed is devolatilized by high temperature steam in the first reactor 3, the remaining fixed carbon becomes activated charcoal coke and ash solids, which continue to move down through the grid 8 and then into the throat 20, then enter the second hard gas 4, where they are oxidized and gasified by a mixture of high temperature air (or oxygen) and steam. When no air or oxygen is fed into the reactor 4 with the steam, no oxidation takes place in the reactor 4, only gasification. The temperature inside the second reactor 4 is further increased to slightly above the ash softening point of the fuel at the grid 5 . Line 9 carries preheated high temperature steam or a mixture of high temperature air (or oxygen) and steam to port 10 and then into second throat 18 .

For wood pellets produced from wood grown in Sweden, the ash softening point is typically 1350-1400°C. If slag formation from the ash is to be avoided, the maximum peak temperature in the reactor 4 during operation should be kept at least 50°C below the softening point of the ash, usually and preferably a maximum of 100°C below.

The temperature in the reactor 4 is controlled by the preheat temperature, the flow rate and the ratio of steam to carbon and, when air or oxygen is used with steam, the ratio of steam to oxygen of the mixture.

The diameter of the second narrowed portion or throat 18 is generally smaller than the diameter of the reactor 4 and preferably also smaller than the diameter of the first narrowed portion or throat 20 . The slope of the tapered portion 17 should preferably be about 45-60°. The diameter of the steam injection port 10 should preferably be 3-5 times smaller than the diameter of the throat 18 .

The ash falls through the throat 18 into the bottom 6 and can be intermittently withdrawn from the reactor.

The synthesis gas flows out through the outlet pipe 12 . Since the temperature in the first reactor 3 is sufficiently high and steam is also present, most of the tar is destroyed and converted into synthesis gas. The main chemicals of syngas are hydrogen, carbon monoxide and methane, carbon dioxide.

The gasifier design of the present invention has the ability to advantageously control the ratio of hydrogen to carbon monoxide in the syngas because the gasifier enables control of the ratio of steam to oxygen in the gasifier over a wide range.

In one embodiment of the operation of said reactor, by controlling the temperature in the second reactor 4 to 700°C, i.e. the same temperature as the first reactor 3, and by feeding only steam, all tars and oils are consumed by said high temperature steam. This converts most of the fixed carbon to activated carbon within the gasifier. Accordingly, the gasifiers and methods described herein are also effective for producing activated carbon. This mode of operation enables very efficient production of activated carbon and also improves the quality of the resulting activated carbon. On the other hand, if gasification is to be maximized, the second reactor should be operated at a higher temperature than the first reactor.

Therefore, the present invention can also be used for the production of activated carbon. There are two ways in which activated carbon can be generated in the reactor. In the first method, only the first reactor is used, ie only high temperature steam is injected through line 7 . The high temperature mixture of steam and air from line 9 is shut off. Another and more preferred method is to operate both reactors but inject only high temperature steam from line 9 . In this case, the activated carbon is collected directly in a dry form. Surprisingly, it was found that the second method resulted in higher quality activated carbon coke. This is believed to be due to the high temperature steam injected through line 9 causing the pores of the activated carbon to open in the second reactor 4 . Therefore, by means of the method of the present invention it is possible to obtain activated carbon with wider pores than in the prior art. The size (pore size) can be controlled by the temperature of the steam in the reactor 4 . Generally, higher temperature steam increases the number of pores in the activated carbon.

Thus, the present invention enables dual production (gas and activated carbon) from one and the same feed 1 . The desired proportion of product can be determined according to the type of feed available, the price of the product, and the like.

In addition, the present invention can be used to treat coarse particle (greater than 0.5 cm in diameter) carbonaceous materials and fine particle and/or liquid feeds.

Figure 3 shows a cross-sectional view of gasifier 21 showing tangential liquid/fines feed injection. Two injection lances 19 ( 19a and 19b ) are shown connected to reactor 4 . The reactor 4 can be injected with a liquid feed such as the liquid residue collected after the micro-oven pyrolysis process of Automotive Shredder Residue (ASR), as well as fine or pulverized feed. The injected feed enters tangentially into the reactor 4 and mixes with the high temperature air/steam from the grid 5 . Tangential injection can increase the residence time of liquid and/or fine feed. The entrained flowing gas passes through the upper fixed bed grid 8 and then enters the reactor 3 through the outlet pipe 12 before leaving the gasifier. The injection port 19 should be located in the lower part of the hearth of the reactor 4 to increase the residence time. Typically, for small gasifiers, the injection port is located 10 cm above the inclined wall 17 .

The residence time can be controlled by the injection rate and the angle of the injection lance to the gasifier.

In a preferred embodiment, the gasifier wall consists of two layers: an outer steel shell, preferably 5.0 mm thick, and an inner fibrous ceramic insulation layer, preferably high temperature resistant high quality ceramic. The ceramic used for the walls 13 and 14 may preferably operate at a temperature of up to 1400°C, ie withstand a temperature of up to 1400°C. _A suitable material may consist of _Al2O3 45%, _SiO2 36%, _Fe2O3 , 0.9%, and _CaO 16%. The ceramics used for the walls of 15, 16 and 17 are preferably operable at higher temperatures of 1400-1500°C. The maximum permissible operating temperature of this wall material is 1600°C. A suitable material may have the following composition: _{Al2O3 61} %, _SiO2 26%, _{Fe2O3 0.5} %, CaO 2.6%, ZrO2 2.95%, and BaO 3.3%. The ceramic material is supported by a steel shell.

In a preferred embodiment, refractory ceramic tubes are used as grids 8 and 5 . The composition of these ceramic tubes can be, for example, 97% ZrO2 and ₃ % MgO.

High temperature steam fed via line 9 , optionally mixed with air or oxygen, enters throat 18 located below grid 5 . This high temperature mixture of air and steam is able to keep the ash in the throat 18 in a molten state, which eventually falls into the bottom 6 and can be withdrawn intermittently.

Example 1:

At room temperature (15° C.), 97 kg/h of wood pellets 1 with a diameter of about 8 mm were fed via inlet 2 into the first reactor by gravity. The properties of wood pellets are listed in Table 1.

Table 1 Composition and elemental analysis of the feed used

Component Analysis Wood pellets (WP) Total moisture (SS187170) 8% Ash content (SS-187171) 0.5-0.6% (dry) LHV(SS-ISO562) 17.76MJ/kg (when received) Volatile substances (SS-ISO) 84% (dry) Density 630-650kg/ ^m3 Elemental analysis (dry composition) wood pellets Sulfur (SS-187177) S 0.01-0.02% Carbon (Leco-600) C 50% Hydrogen (Leco-600) H 6.0-6.2% Nitrogen (Leco-600) N＜0.1% Oxygen (calculated value) O 43-44% Ash melting temperature (oxidation condition) wood pellets start deforming, IT 1350-1400℃ Soften, ST 1450-1500℃ Hemisphere, HT 1500℃ Fluid temperature, FT 1500-1550℃

Example 2

60 kg/h of waste-derived fuel (RDF) with a diameter of about 8 mm, a pellet-type fuel made of paper fibers mixed with other substances such as textile fibers, wood chips and plastics, was used as feed and heated at room temperature (15°C) Feed into the first reactor 3 is from the top 1 by weight (ie by gravity). The properties of the RDF particles are shown in Table 2.

Table 2 Composition and elemental analysis of the RDF feed used

Component analysis Waste Derived Fuel (RDF) Total moisture (SS187170) 2.9% Ash content (SS-187171) 6.0% (dry) LHV(SS-ISO562) 26.704MJ/kg (when received) Volatile substances (SS-ISO) 84.4% (dry) Density 472kg/ ^m3 Elemental analysis (dry composition) RDF Sulfur (SS-187177) S 0.09% Carbon (Leco-600) C 63.3% Hydrogen (Leco-600) H 8.9% Nitrogen (Leco-600) N 0.3% Oxygen (calculated value) O 20.95% Ash melting temperature (oxidation condition) RDF start deforming, IT 1210°C Soften, ST 1220℃ Hemisphere, HT 1230℃ Fluid temperature, FT 1240℃

Claims (9)

1. be used for being produced by thick carbon-containing feeding the two stage gasification device (21) of synthetic gas and optional gac, this gasifier comprises:

-be equipped with the inlet (2) that is used for thick carbon-containing feeding (1) and be used for steam first the inlet (7) first reactor (3); And

-be equipped with and be used for steam, optional with air or oxygen, second reactor (4) of second inlet (9);

-and the outlet (12) that is used for synthetic gas;

Wherein said first and second reactors are had the crevice (20) of the cross section that reduces and are separated, this crevice is used to limit the circulation of unreacted solid carbonaceous substance from first reactor to second reactor, wherein said first reactor can move under at least 600 ℃ temperature, and wherein said second reactor can move under higher temperature, it is characterized in that, described second reactor (4) is the bottom reactor, described first reactor (3) is a upper reactor, be equipped with grid (8) in the bottom of first reactor, inlet (7) is set to close on the bottom of described first reactor, thereby the pre-hot steam of temperature at least 700 ℃ can be fed to described first reactor from grid (8) below via inlet (7), described second reactor is equipped with the inlet (19) that is used for thin solid carbon charging and/or liquid carbon-containing charging, inlet (9) is set to close on the bottom of described second reactor, thereby can be at least 700 ℃ pre-hot steam with temperature, optional preheated air or oxygen with uniform temp, be fed to described second reactor from the below via inlet (9), and be equipped with second crevice (18) with the cross section that reduces in the bottom of described second reactor (4).

2. two stage gasification device according to claim 1, wherein one or more, and preferably all described inlets (7,9,19) all have circular in the corresponding section (20,18,16) of described gasifier of cross section tangentially enter in the described gasifier.

3. two stage gasification device according to claim 1 and 2, wherein said inlet (19) comprise the inlet (19a, 19b) that at least two apart maximum distances of the circumference along described circular cross section distribute.

4. using to have two reactors, is respectively first and second reactors, the two stage gasification device thick carbon-containing feeding that gasifies, to produce synthetic gas and optional process of active carbon, comprise the steps:

(a) thick carbon-containing feeding is fed in first section reactor of gasifier;

(b) under at least 600 ℃ reactor service temperature, make steam in first section reactor of described thick carbon-containing feeding contact, realizing the gasification of described carbon-containing feeding,

It is characterized in that, feeding oxygen in described first section reactor not, and only feeding temperature be at least 700 ℃ pre-hot steam, and optional in any solid of step (b) gained and/or the second section reactor that the liquid carbon-containing material moves under the temperature at least 700 ℃ contacted, with the pre-hot steam of air or oxygen to obtain the arbitrary combination of following product: gac; CO; CO ₂, and the combustion heat.

5. method according to claim 4 comprises another step (d), wherein thin solid carbon of feeding or liquid carbon-containing charging in second section reactor of gasifier simultaneously.

6. according to claim 4 or 5 described methods, wherein in step (c), the steam that enters second section reactor is preheated to 700-1600 ℃ temperature, and preferred 800-1200 ℃.

7. each described method among the claim 4-6 is wherein selected the steam/air used in the step (c) or the ratio of steam/oxygen gas, thereby internal-combustion is minimized, and the yield of maximization CO and/or gac.

8. according to each described method among the claim 4-7, wherein use the oxygen replaces air.

9. according to each described method among the claim 4-6, wherein not to described gasifier supply air or oxygen.

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