JPS6157684A - Production of gas from solid fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses one or more gasifying agents by means of a fluidized bed and dust gasification to feed crude solid fuel and gasifying agent into a fluidized bed, and from the bottom of the fluidized bed. The solid gasification residue is discharged and the product gas rising upward from the fluidized bed is directed into a steadying and after-rea.
ction 5 pace) and then remaining in the fluidized bed.

Methods for gasifying carbon-containing solid fuels in reactors integrating packed beds, fluidized beds and flue gasification stages are known from numerous publications.

The combination consisting of a fluidized bed in which the reactor is the main stage, a packed bed stage placed below the fluidized bed, and a dust gasification stage placed above the fluidized bed is DE-B-2.
640180. However, the practical advantages of such a combination, namely the heat exchange between the very hot dust gasification products and the much colder fluidized bed, are not pointed out or provided for therein.

According to DE-A-2742222, a cyclone is installed in the middle of the reaction space of the fluidized bed reactor above the fluidized bed, which cyclone ensures the separation of product gas and coke dust. The production force is withdrawn from the top of the reactor, while the coke dust descends through a cyclone, enters a water injector using oxygen and steam as propellants, and then enters a gasification chamber.
There is insufficient cooling here, so
There is insufficient gasification time available to gasify the coke dust.

DE-A-2925441 provides a weir between the cyclone separator and the coke combustion chamber to overcome pressure loss;
A process is also described in which a plurality of dust gasification chambers are provided on a slope within a fluidized bed reactor. Due to the slanting arrangement of the flue gasification chamber, the gaseous flue gasification products create problems because the forces exerted by the gas flowing over the fluidized bed are not uniform (the slanting arrangement of the flue gasification chamber In addition, a pressure-resistant weir valve must be developed that is capable of conveying a stream of coke dust at 1000° C. under high pressure.

Known processes consisting of several integrated gasification stages increase their susceptibility, but their availability
It has an adverse effect on the industry and is technically complex. 1
If one gasification stage is missing, the other gasification stages can no longer operate on their own. The individual gasification stages are interdependent. Repairs to any one stage will shut down the entire plant, reducing its effectiveness. However, the effectiveness of linked production plants depends on their effectiveness. In particular, the aim is to make available a process and a plant with a high degree of efficiency, and to utilize as much of the heat released during this process as possible in the gasification process itself. Finally, the gasification efficiency of known processes is improved by converting the fuel used as completely as possible.

This purpose is based on the process according to the invention as described above, that is, the smoke dust contained in the product gas is separated outside the fluidized bed reactor, and the separated smoke dust and gasification agent are placed at a location away from the fluidized bed reactor. The dust gasification reactor located at This is accomplished by discharging into a fluidized bed.

The process according to the invention is a synthetic gas for the chemical industry.

It can be used to produce reducing gas for metallurgical processes, heating gas for power plants, etc., and in particular, it can be used for producing gas for gas turbines/steam turbines as well as for other stages and interfaces.

The method of the invention offers a number of important advantages compared to known processes. Several gasification stages can be integrated while the individual gasification stages have the desired design. Furthermore, it is also possible to disassemble individual gasification stages to a large extent, so that the absence of one gasification stage does not result in a shutdown of the entire plant.

Finally, the process of the invention allows the considerable heat of the dust gasification products to be utilized for gas production in a fluidized bed stage.

A portion of the waste heat can be used for the production and preheating of the gasification medium.The production costs of coal are low and the carbon conversion rate is higher than either of the individual processes. No condensable components appear in the product gas. The gas outlet temperature, slag outlet temperature and oxygen consumption each correspond to the values of a conventional fluidized bed gasification process and are lower than in the case of a pure flue gasification plant.

However, the gasification efficiency is greater than a pure fluidized bed as well as a pure flue gasification plant.

Solid fuels used in the process of the invention are, for example, lignite, anthracite, beets, wood, etc. Preferred fuels are lignite and anthracite. Note that liquid fuels can also be used or added to solid fuels. When coal is used, it is pre-pulverized and dried, e.g.
The residual moisture content is less than 12% for lignite and 5% for anthracite.
% or less.

Coal introduced into a fluidized bed for gasification is first heated to the temperature of the sliding bed, and the time required for this varies depending on the particle size of the coal and other factors. For particles having a particle size of 0.1'111 or less, the temperature of the center of the particles is raised to 900 to 1000 DEG C. by heating for about 0.1 to 0.2 seconds.

It takes about 2 seconds for a particle size of 11111 to be heated to this temperature, and about 100 seconds for a particle size of IQmm. This heat treatment simultaneously degasses the coal. 0.1
It takes about 3 seconds to remove volatile components from coal with a particle size of +u+ or less to a residual volatile content of about 2%.

For particles with a large particle size, a longer heating time is required in proportion to the above-mentioned heating time. The gaseous medium introduced and the gas evolved produce a gas stream that rises at a predetermined rate, depending on the quality of the coal used and the diameter of the fluidized bed. The required velocity corresponds to the particular particle size, with relatively fine particles floating upwards and relatively coarse particles sinking downwards. However, in a fluidized bed, the particles constantly change their position, so continuous deceleration and acceleration occur at the same time as they are pulverized.
Both fine and coarse particles remain in the fluidized bed for a period of time before being separated.

In experiments using a fluidized bed at normal pressure, the W content of the pure substance was about 2%.
is separated downwards, but the (partially) degassed pure material, i.e. actually more than half of the carbon, is discharged upwards. The fine powder discharged upward is still 5
%, but the temperature corresponds to the temperature of the fluidized bed, e.g. The medium grain sizes remaining in the fluidized bed generally require 10 to 10% volatile components to be gasified. It takes 20 minutes.

This means that in a fluidized bed the volatile components are mostly liberated and the medium particles of introduced fuel are essentially completely gasified, whereas the particles that sink to the bottom or float to the top are partially gasified. This means that degasification is carried out at the same time, and that gasification is carried out partially.

For lignite, the fluidized bed stage is e.g. 800-850
℃, and in the case of anthracite, it is operated at 950-1050℃. This temperature limit is determined by the natural softening point. In order to avoid the phenomenon of covering the reactor walls and associated equipment, the fluidized bed temperature is at least 100-150 °C below the softening point. It should be the temperature.

If the fluidized bed stage is considered to be the main stage in combination with other gasification stages, these gasification stages can collect the downwardly sinking solids in their own stage (located in the same space as the fluidized bed stage). This serves to improve the efficiency of the main stage, which can be gasified in a particularly suitable gasification stage, and also converts solids floating upwards in a particularly suitable gasification stage. However, each of these gasification stages has its own requirements.

Fluidized bed reactors can be designed to operate in the most economical manner for the gasification of fuels, such as anthracite or brown coal. The fluidized bed stage may be combined with a packed bed stage located directly below it.

Gasification is suitably carried out under pressure, preferably between 1 and 40 bar. However, it is also possible to carry out under normal pressure.

The gasifying agent used is oxygen, an oxygen-containing gasifying medium and/or steam, or a mixture thereof. Preferred are oxygen or air and steam. The gasifying medium, oxygen or steam, is introduced into the conical bottom of the fluidized bed zone by known methods. Preferably,
This gasifying agent is fed to the fluidized bed at different levels by several gas and other agent nozzles distributed around the fluidized bed reactor.

The solid fuel may be supplied in a conventional manner, for example by a conventional screw method, in which coal is forced into a pile into a fluidized bed. However, preferably a high speed rotating screw (eg 1500 rpm) is used, by means of which individual coal particles are ejected or ejected into the fluidized bed.

This feeds the individual coal grains into a zone of the fluidized bed where high heat transfer values predominate, and very rapid heating can be expected.

The faster the heating rate, the less the effect on the scorching properties of the coal, since the combustible parts deposited or formed from the coal surface evaporate quickly and no scorch occurs outside the coke layer anymore. .

The burning temperature range of coal is between 300 and 500℃, especially 40℃.
It is near 0°C. It is important to exceed this temperature range as soon as possible. This is a phenomenon that grows from the outside inward and clogs the fluidized bed reactor.
It is also possible to avoid the phenomenon of adhesion to the wall soil of the fluidized bed reactor.

In order to form a homogeneous fluidized bed, i.e. a uniform flow for the solids, the gasification medium oxygen and steam are preferably fed from as many feed ports as possible distributed around the fluidized bed reactor. It should be fed to the fluidized bed at different levels. In this case, if a packed bed is not provided below the fluidized bed, it is also possible to feed only the steel 1, for example, from the bottom of the fluidized bed to ensure cooling of the solids deposited below. be.

What is particularly important is the method of supplying oxygen. In the conventional process, even coal with poor combustibility is pureed into the fluidized bed through a nozzle from a position close to the reactor wall, where it forms deposits in extremely hot spots on the reactor wall. Oxygen was being injected into it. It was then proposed to introduce steam around the nozzle to reduce wall buildup. Furthermore, it was proposed to stop using pure oxygen and mix oxygen and steam before entering the reactor. However, this method lowers the oxygen concentration and further lowers the fluidized bed temperature. However, the largest possible zone of the fluidized bed is heated to very high temperatures, e.g. 1100-1300°C.
In this zone, carbon conversion takes place very rapidly, and the temperature is very close to the natural softening point, causing ash agglomeration, forming large lumps, and dispersing the ash below the fluidized bed. We should aim for a state where Because the heat transfer in the fluidized bed is large, the temperature toward the vessel wall quickly decreases, and the temperature at the location where the vessel wall is exposed to heat is low. The temperature at which no adhesion to the vessel wall occurs prevails. Although it is true that such high temperatures can be reached with known oxygen supply methods, it is not possible to confine this temperature to the center of the reactor, and therefore deposits on the reactor walls occur. .

Therefore, it is important to create a high-temperature zone in the fluidized bed at an appropriate distance from the reactor wall, allowing on the one hand a high conversion rate and adequate ash agglomeration, and on the other hand, a high heat transfer to maintain the temperature at an appropriate level. The aim is to remove significant ash from the reactor walls down to Preferably, this is done by introducing the gasifying agent into the fluidized bed through a dual-substance nozzle designed with double tubes, i.e. oxygen or oxygen-containing medium is introduced from an inner feed tube, and the inner feed tube is connected in concentric circles. This is achieved by introducing steam from an external supply pipe surrounding the area. This results in only oxygen acting at a certain distance from the reactor wall. This method allows the creation of a large high temperature area at a suitable distance from the reactor wall.

Above the fluidized bed of the fluidized bed reactor is provided a region of suitable size and height, and by adding a gasifying agent, in particular oxygen, the upper gasification can be carried out above the fluidized bed.

This is particularly important for lignite gasification. The dimensions and shape of the predetermined region which is the space after the reaction is completed are determined by economic considerations. The cost of additional oxygen consumption and the cost of the desired enlarged upper reaction space in proportion to the additional carbon conversion sets a limit to the point where it is no longer economical. Generally, when anthracite is gasified and discharged from above the fluidized bed, the residence time (a
period of dwell) (this value was derived from an atmospheric pressure plant) is economically preferred.

When such upper gasification is carried out, about 40-50% of the introduced carbon is used for the gasification of anthracite, and about 10-15% of the introduced carbon is used for the gasification of lignite in the fluidized bed reactor. is emitted as dust.

A flue gasification reactor placed after the fluidized bed reactor serves to gasify these.

Dust gasification as a separate stage converts coal into Q, 1 mm
It is required to grind to the following particle size (average particle size of about 0.031 m). However, the fine dust released from the fluidized bed has an average particle size 2 to 5 times larger than this value. Normal dust gasification occurs at about 1600'C.

Generally, the gas outlet temperature is about 1500℃, and the temperature of the liquid slag extracted from the bottom is about 1300-1400℃
It is.

To avoid freezing of the dust gasification reactor, the gas outlet temperature should always be about 80-150'C higher than the melting temperature of the slag. Therefore, the coke dust discharged upward from the fluidized bed should be gasified in the flue gasification stage, even if its treatment requires a long time. Normally, in the case of normal dust gasification with the average particle size (approximately 0.03u+) described above, in order to convert it into carbon, it is necessary to
1.5 seconds is sufficient, but in the case of coke dust from fluidized bed plants a time of up to about 4 seconds must be considered.

The advantage here is that the coke dust is already at a high temperature, e.g. IOO, when it is introduced into the dust gasification reactor.

It is at a temperature of ℃. When mixed with a given transport medium, such as steam, the temperature will be between 600 and 900°C. The higher temperature compared to the gasification of conventional coal dust aids the gasification process and results in a considerably shorter gasification time than, for example, the time required to gasify coke dust at a lower temperature. However, as a rule, this coke carbon requires a longer residence time than the very finely ground fuel for conventional coal dust gasification.

If the dust gasification raw acids, gas/residual dust and liquid slag are introduced into the fluidized bed at high temperature and correspondingly high content of the dust gasification stage, they will release their heat to the fluidized bed and Increasing the temperature will reduce the oxygen consumption of this gasification stage. Also, overall carbon conversion would be obtained that is not achieved by any individual process.

Taking advantage of all technological possibilities, including the development of prototype devices expected in the future in terms of temperature resistance, solidity, etc.
Gasification efficiency will be even higher than it is now.

The gasification of the fuel dust discharged from the fluidized bed takes place in a dust gasification reactor equipped with a dust gasification burner at the top, into which the gasification agent and the solids to be gasified are introduced, mixed and simultaneously ignited. Also, the flow direction within the gasification reactor extends downward from the top of the reactor.

Preferably, the dust gasification reactor and the fluidized bed reactor are
The gas outlet of the dust gasification reactor is located at a higher level than the surface of the fluidized bed, and the dust gasification product introduced into the fluidized bed is installed at a spatial distance so that it is introduced through a connecting pipe.

This arrangement allows product gases to flow in opposite directions. The product gas of the fluidized bed flows upward and the product gas of dust gasification flows downward, and the flow direction in the dust gasification reactor extends vertically from the top downward.

The dust gasification reactor according to the present invention is installed at a spatial distance from the fluidized bed reactor, and its shape and layout are independent from the fluidized bed reactor. For example, the room may be uncooled or may be provided with suitable cooling means. In the case of a cooled room, a certain amount of heat is removed from the process and transferred to the cooling water,
Disappear. This movement is called hot cooling.
), it can be used for steam generation. The advantage of an uncooled system is that virtually 100% of the heat obtained in the reactor can be used for the gasification process.

The transport of the flue gases is carried out using a gaseous transport medium, preferably a gasifying agent, especially steam, or other gases such as CO2.
If carried out with the help of such as
Supplied at a temperature of 0°C.

However, the dust may also be mixed with high-boiling gasifiable liquids, such as heavy oil or tar, and introduced as a mixture into the dust gasification reactor, where it is gasified with the aid of a gasifying agent. Since the dust is mixed with the liquid at high temperatures, the vaporization point of the liquid is high enough that the solid-liquid mash can be pumped and introduced into the reactor.

For flue gasification, the same gasifying agents used for fluidized bed gasification can be used. Preferred are oxygen and steam, but other suitable gasifying agents can also be used.

The dust gasification reactor, which is placed at a distance, is designed independently of the dimensions of the fluidized bed reactor, based on the required gasification time, for example a gasification time of about 4 seconds. 1
For known combinations of a fluidized bed stage and a dust gasification stage in one reactor, there is no such freedom; the fluidized bed stage and the dust gasification stage are mutually compatible and suitable for a common reactor housing. It has to be something.

A dust gasification burner is installed at the top of the dust gasification reactor, with the help of which the gasification media oxygen and steam and the solids to be gasified are introduced into the reactor, mixed and ignited at the same time. Burner types known from other dust gasification processes may be used, provided they are compatible with the intended application. According to the invention, spiral burners are preferred.

Preferably, the gasification agent is introduced into the dust gasification reactor via a burner, but the gasification agent is introduced along the length of the dust gasification reactor in order to maintain a uniform high temperature profile over a longer section. It may also be fed via a plurality of distributed additional nozzles.

The dust gasification products from the dust gasification stage, i.e. the product gas at about 1500°C, the residual solids with the same temperature and the liquid slag with a temperature of about 1300-1400°C, are transferred to the fluidized bed via a connecting pipe. Here, the heat held by each is released to the fluidized bed to raise the temperature of the fluidized bed, for example, to create a heat difference of 1500°C to 1000°C. If the fluidized bed is sufficiently cold, the liquid slag will solidify and fall downwards from the fluidized bed due to its own lumps.

However, the slag heat from the flue gasification that is available in the fluidized bed is 0.0% relative to the overall system gasification efficiency.
When contributing less than 5%, from an economic standpoint, the liquid slag is not returned to the fluidized bed, but is discharged at the outlet of the dust gasification reactor and led to a water bath, where it is granulated, separated and produced. It would be justified to feed only gas and residual solids from the dust gasification reactor to the fluidized bed.

Returning the liquid slag to the fluidized bed is cumbersome in the deformation process described below. Therefore, it is meaningless. Nevertheless, the loss of considerable heat contained in the liquid slag can be avoided by the deformation process described below, and this heat can be utilized for the overall process.

For this purpose, a special fluidized bed stage is provided after the tl m gasification stage, which is operated with inert solids, such as slag, and steam as fluidizing agent. An outlet is provided between the dust gasification stage and the inert material fluidized bed for the produced gas and the fine residual carbon particles accompanying the gas, and these are returned to the normal fluidized bed gasification stage, while the liquid slag remains in the dust gasification stage. The inert material flows downward from the stage into a fluidized bed where it solidifies before being discharged from the bottom of the fluidized bed. The heat removed from the liquid slag is transferred to steam used as a fluidizing agent, which is introduced from the dust gasification stage with the product gas into the fluidized bed reactor.

Furthermore, with the aid of additional heat exchange surfaces, steam can be generated in an inert fluidized bed.

The dust gasification stage may be of the entrained flow type, as described above, or may operate on liquid media. For example, slag or iron can be used as the liquid medium. In this case, the dust to be gasified and the gasifying agent are blown into or onto the liquid medium, and the gasifying agent and the dust are heated very quickly to the temperature of the surrounding liquid medium. This temperature is in the range of about 1600° C. and the reaction takes place correspondingly quickly.

If a liquid slag is used, it is conveniently produced from coal fractions, and if a liquid iron bath is used, it is formed, for example, from crude iron.

If the liquid slag from the flue gasification stage is not returned to the fluidized bed gasification stage, only the flue gasification gas is returned and the total process produces about 115 to 1
Only the /6 sediments downward and enters the fluidized bed gasification stage, where it becomes coarse particles or lumps together with carbon. This carbon may be gasified in a packed bed stage located below the fluidized bed if it is easily contacted with the gasifying agent. but,
Generally, the slag and carbon deposits are too small to warrant a packed bed stage. When this amount is large, it is necessary to design additional processes, control the entire process, and adjust expenditures. Under these circumstances, especially when carbon-rich slag is produced, it is desirable to provide a packed bed stage.

The carbon-containing slag discharged from the bottom of the fluidized bed reactor may be crushed under operating pressure and introduced in the form of dust from the fluidized bed gasification stage to the flue gasification stage together with coke powder to remove residual carbon. It may be gasified, while the ash of the coal is melted and extracted as slag. Slag can be disposed of more easily than ash, and if the latter is present in large quantities it can be washed off with water.

According to the invention, the gasification of the dust can also be carried out in a cooled dust gasification stage.

In the case of a cooled flue gasification stage, a certain amount of solids is required for a given geometry to prevent slag solidification and ensure slag outflow despite the loss of heat due to cooling. It is.

The amount of fine coke dust discharged upwards from the fluidized bed gasification stage depends not only on the pressure, but also in particular on the type of coal used, ie the cracking behavior of the coal in the fluidized bed. Highly volatile anthracite coal decomposes again better than less volatile coal, but lignite decomposes more quickly and finely than anthracite in a fluidized bed.

According to this process, the dust gasification stage can be carried out intermittently rather than continuously, the coke dust from the fluidized bed is stored in a storage tank and isolated from heat, and the dust gasification is carried out only periodically. You can. Furthermore, the dust gasification may be carried out in several dust gasification reactors arranged around a fluidized bed gasification stage, several of which are operated in parallel.

In this case, the capacity of one dust gasification stage must correspond to the minimum amount of dust expected to be released from the fluidized bed. For larger amounts of emitted dust, one or several other dust gasification stages will be operated. However, in this case it is preferable to supply both the dust gasification gas and the liquid slag to be returned to the fluidized bed gasification stage, and the liquid slag should not be separated but subjected to special treatment.

FIG. 1 diagrammatically shows an embodiment of the process according to the invention.

The coal production plant 1 also includes suitable storage tanks, feeding equipment, etc., from which coal, pulverized to a medium particle size corresponding to the operating pressure, is transferred to a weir 2, where this fuel is used as required. pressure is applied. From the weir 2, the solid fuel is transferred to distribution means 3, with the aid of which it is introduced into a fluidized bed reactor 4. For this purpose, for example, a rapidly running screw is used, with the aid of which the individual solid particles are forced into the fluidized bed. Additionally, gasifying media, such as oxygen and steam, are supplied to the reactor 4 via tubes 5 and 6.
The reactor is fed from different levels, each level consisting of a number of nozzles distributed around the reactor.

Oxygen and steam may be supplied separately or together. In all cases, a ring of steam is formed around the oxygen, which acts only at a certain distance from the reactor wall.

Coke material is discharged upward from the fluidized bed reactor 4 together with the produced gas, and is separated from the produced gas in the separation tank 7 .

The hot product gas is cooled in a heat exchanger 8 and the removed heat is used to produce steam. A portion of the steam is returned to the process and the remainder is used in the steam power plant. The cooled gas is sent to the intended use via a gas cleaning device 9. The heat exchanger 8 may be distributed or placed after the gas scrubber, provided that the gas scrubber can also operate under pressure and at high temperatures.

The coke dust separated in the separation tank 7 is transferred to the pressure forming stage (
pressure build-up stage)
1Q, but a storage tank 11 may be provided before that if desired. From a pressure building stage 10, for example a weir, the coke dust is led to a buried gasification stage 12;
At the same time, oxygen and steam are introduced as gasifying media through pipes 13 and 14. Of course, the coke dust itself may be blown in with steam or with other suitable gaseous media, such as CO2 or product gas. The product gas from the dust gasification stage 12 is fed via pipe 17 to the fluidized bed reactor 4 .

A slag channel is provided at the outlet of the dust gasification stage 12 in which liquid slag accumulates and flows as an overflow via a pipe 15 to an inert material fluidized bed 16. At this stage, the slag itself may be used as an inert material and the excess slag may be withdrawn downwards via a slag crusher 17. In this slag crusher, the slag is crushed to the dimensions described above for disposal and removed from the pressurized zone in the connected weir 18. Humidifier 19 is used for final cooling of the slag.
It was carried out with the help of

Steam is used as a fluidizing agent in a fluidized bed of active substances.
This steam is heated by removing heat from the slag, which is then fed via pipe 21 to the fluidized bed.

Discharged from the bottom of the fluidized bed reactor 4, 111 solid particles consisting of coal ash and carbon are sent by a discharging means, for example an inclined screw, to the comminution means 23, where they are crushed and $'t). It becomes dust and is sent directly to the dust gasification stage 12 by the transfer means 25, or sent to the pressure forming stage 10, or crushed by the crushing means 23 to a particle size suitable for disposal, and then sent to the humidifier 24. After being cooled down to a predetermined temperature, it is transported to a disposal site.

The fine dust separated in the heat exchanger 8 and gas cleaning device 9 passes through pipes 28 and 29 to the dust gasification stage 12.
is returned to the storage tank 11 located in front of the tank.

If there are problems with the dust gasification stage, the fluidized bed gasification can be operated in conjunction with itself. For this purpose, the pipe 17° leading from the dust gasification stage to reactor 4 and the pipe 21 leading from the inert fluidized bed to reactor 4 are blocked, and the connecting pipe leading from storage tank 11 to weir 10 is blocked. .

If the capacity of the storage tank 11 is insufficient for the time required to solve the problem, the coke dust separated in the separation tank 7 is discharged from the connected storage tank 11;
It is stored at intermediate pressure 31 via pipe 30.

If there are problems with the fluidized bed stage, the dust gasification stage can be operated continuously on its own. For this purpose, a pipe 1 leading from the flue gasification stage to the reactor 4
7' and pipe 2 leading from the inert fluidized bed to reactor 4.
1, and also the pipe leading from the transfer means 25 to the weir lO and the communicating pipe from the reactor 4 to the separation tank 7.

Open tubes 26 and 27. Smoke gasification storage tank 1
Coal dust from 1 or through pipe 32 and weir 1° to intermediate pressure 3
It can be operated continuously with coal dust coming from 1. It is also possible, for example, for coal dust to be supplied via pipe 33 and weir 10 from a crushing plant of a steam generator and used in dust gasification stage 12 .

[Brief explanation of drawings]

FIG. 1 diagrammatically shows an embodiment of the process according to the invention. 4... Fluidized bed reactor. 5.6... Pipe for gasifying agent supply.

Claims (12)

[Claims] (1) Fluidized bed and dust gasification using one or several gasification agents to feed crude solid fuel and gasification agent into the fluidized bed, discharge the solid residue from the bottom of the fluidized bed, and remove the solid residue from the fluidized bed. In a method for producing gas from solid fuel by passing the product gas rising upward from the bed through a predetermined region and leaving it in the fluidized bed, the smoke dust contained in the product gas is removed from the fluidized bed reactor. The separated dust and gasification agent are led to a dust gasification reactor located remote from the fluidized bed reactor, where they are gasified to a significant extent at a temperature above the melting point of the ash, and then A process for the production of gas from solid fuels, characterized in that the gas produced during dust gasification is returned to the fluidized bed to release a significant part of the heat contained in the gas into the fluidized bed. (2) A method according to claim 1, wherein the gasification is carried out at a pressure of 1 to 40 bar. (3) The gas outlet of the dust gasification reactor is located at a higher position than the surface of the fluidized bed, and the dust gasification product of the fluidized bed is supplied through a connecting pipe. the method of. (4) Any one of claims 1 to 3, wherein the gasifying agent is supplied to the fluidized bed at different levels by several gasifying agent nozzles distributed around the fluidized bed reactor. The method described in. (5) The gasifying agent is supplied from the double pipe structure gasifying agent nozzle,
Claims 1 to 4 in which the fluidized bed is supplied by supplying oxygen or an oxygen-containing medium through an inner supply pipe and supplying steam through an outer supply pipe concentrically surrounding the inner supply pipe. The method described in any of the paragraphs. (6) When the slag discharged from the bottom of the fluidized bed reactor has a high carbon content, the slag is crushed and supplied to the dust gasification reactor according to any one of claims 1 to 5. Method described. (7) Performing dust gasification by introducing a gasifying agent and a solid to be gasified into a dust gasification reactor equipped with a dust gasification burner at the top, mixing them, and simultaneously igniting them;
Claims 1 to 6 further characterized in that the flow direction in the dust gasification reactor extends vertically downward from the top of the reactor.
The method described in any of the paragraphs. (8) The method according to claim 7, in which the flue dust is fed to a flue gasification reactor in a high temperature state at a temperature of about 600 to 1000°C. (9) Feed the liquid slag from the flue gasification to a fluidized bed operated with an inert solid, such as slag, and steam as a fluidizing agent, so that the gaseous products of the flue gasification and the inert material 9. A method as claimed in claim 7 or claim 8, in which steam from the fluidized bed is fed to a fluidized bed gasification stage. (10) Claims 1 to 6 in which the dust gasification is carried out in a liquid bath of slag or iron, and the solid to be gasified and the gasifying agent are blown into or onto the liquid from the top of the reactor.
The method described in any of the paragraphs. (11) A method according to any one of claims 1 to 8, in which the liquid slag produced during flue gasification is fed into a gasification fluidized bed. (12) Claims 1 to 1 in which the dust gasification is carried out in several dust gasification reactors that are operated in parallel.
The method described in any of Item 1.