JP2005531673A - Method for gasifying solid carbonaceous raw material and reactor used in the method - Google Patents

Abstract

A method for gasifying a solid carbonaceous feedstock, wherein the gasification is performed in an elongated gasification reactor vessel, the vessel being a cooling channel coaxial with a gasifier device, through the cooling channel. The cooling channel for discharging the gasification device hot dusty product from the reactor, and quenching the dusty hot gas product at a location downstream of the gasifier device. Means for supplying gas, and at a rate sufficient to prevent hot gas containing dust from flowing from the cooling channel to the annular space, the dust-free gas and the wall of the reactor vessel. The gasification method for supplying an annular space between the cooling channels.

Description

  The present invention relates to a method for gasification of a solid carbonaceous feedstock, which gasification takes place in an elongated gasification reactor vessel, which comprises a gasifier device and a coaxially arranged cooling channel. A cooling channel for discharging hot gaseous products containing dust from the gasifier device through the cooling channel from the reactor, and dust at a location downstream of the gasifier device. Means for supplying a quenching gas to the hot gaseous product.

  Such a process is described in U.S. Pat. No. 4,859,213. This publication describes a typical coal gasification process that takes place in an elongated gasification reactor vessel, the vessel comprising a gasifier device and a coaxially arranged cooling channel comprising the cooling channel. Through the cooling channel for discharging the gasifier device dusty hot gaseous product from the reactor, and quenching the dusty hot gas product at a location downstream of the gasifier device. Means for supplying a gas. The pulverized coal from the coal supply system is supplied to the gasifier device through the burner together with the oxygen-containing gas. In the gasifier, the pulverized coal is partially oxidized with oxygen to become a carbon monoxide-hydrogen containing gas (synthesis gas) (also referred to as product gas). Ash in the form of slag descends by gravity in the cooling channel and enters a slag tank tank located at the lower end of the elongated reactor. Product gas containing dust and entrained droplets of liquid slag rises in the cooling channel to the quench section. The quenched product gas exits the gasification reactor via a duct and enters a waste heat boiler or a syngas cooler. Solids are removed from the resulting cooled product gas in a so-called solids removal section. A portion of the cleaned and cooled gas from the solids removal section is then forced back by the recirculation gas compressor and entered into the cooling channel as a quench gas. This quenching gas entering the cooling channel cools the product gas so that the entrained flight slag particles solidify and do not stick to the surface of the duct or waste heat boiler during the passage of solids and gases.

  For example, as disclosed in U.S. Pat. No. 4,859,213, a carbon gasification process converts a carbonaceous feedstock into a hot product gas under high temperature and pressure. The inert ash component contained in the carbon is partially discharged from the gasification reactor in the form of fine dust along with the hot product gas stream. Components used in gasification processes such as gasification reactors, quenching means, cooling channels, ducts and downstream heat exchangers that heat the surface, as the gasification pressure is up to 50 bar and higher Must be operated in a pressure wall that can be realized by one or more pressure vessels or pressure mantles. In order to protect the reactor pressure mantle against high syngas temperatures above 1500 ° C., the quench tubes and cooling channels are equipped with water-cooled cooling surfaces. The high-temperature product gas containing dust is cooled to a temperature of about 900 ° C. by a low-temperature quenching gas supplied from a quenching gas supply device. Further cooling occurs at the surface of one or more heat exchangers downstream of the quenching device to produce steam.

  As shown in U.S. Pat. No. 4,859,213, an annular space is created between the cooling channels and pressure walls of the gasifier device, quenching device and gasification reactor.

  The cooling surface of the cooling channel can only withstand small pressure differences on the gas side. Thus, the pressure between the interior of the cooling channel and the annular space must be substantially compensated. The opening that fluidly connects the cooling channel and the annular space is, for example, a slide point on the wall of the cooling channel to compensate for thermal expansion, and an opening in the quenching device.

For this purpose, at least the sliding point associated with the cooling channel is opened or a gas permeable plug is provided to compensate for the pressure in the hot gas guide channel segment separated from the pressure wall by the gas barrier. That is, Dr. G. Keintzel and Dipl. -Ing. Speech Gawlowski "gasifier and syngas cooler design criteria (Criteria for Design of Gasifier and Syngas Cooler)", Conference EPOS 2000 - International Conference on Efficiency, Cost, Optimisation, Simulatiion and Environmental Aspects of Energy and Process Systems, July 5-7, 2000, Twente University, Enschede, The Netherlands, known from the figure "Heating Surfaces in the Synchronous Cooler". Thus, during the pressure compensation, the hot product gas containing dust enters the annular space. In industrial scale carbon gasification plants, it has been found that unwanted flow on the gas side occurs in an annular space filled with gas (ie, so-called secondary flow). This allows hot gas to cool on the side of the cooling surface directed towards the annular space and on the pressure wall, and the cooled gas can flow back to the cooling channel via the slide point. Because. In this way, undesired heating of each pressure wall region and condensation of dust occurs. This can cause operational failure.
US-A-4859213

  The object of the present invention is to provide a gasification process as generally described above, wherein the product gas containing dust cannot enter the annular space and thus dust accumulation is avoided. It is.

  The following process achieves this goal. A method for gasifying a solid carbonaceous feedstock, wherein the gasification is performed in an elongated gasification reactor vessel, the vessel being a cooling channel coaxial with a gasifier device, through the cooling channel. The cooling channel for discharging the gasification device hot dusty product from the reactor, and quenching the dusty hot gas product at a location downstream of the gasifier device. Means for supplying gas, and at a rate sufficient to prevent hot gas containing dust from flowing from the cooling channel to the annular space, the dust-free gas and the wall of the reactor vessel. The gasification method for supplying an annular space between the cooling channels.

  The applicant supplies such dust-free gas to the annular space, so that the hot product gas containing dust passes through the opening at the slide point or the quenching supply means on the wall of the cooling channel. I found that I didn't. A so-called positive flow of dust-free gas exists from the annular space to the cooling channel. In order to reach such a positive flow, the speed of the dust-free gas supplied to the annular space is such that the pressure in the annular space is at least equal to or slightly higher than the pressure in the cooling channel. It is preferable to do this. The above is also called a pressure compensation method.

  Again, since secondary flow is effectively suppressed, unacceptable heating of the pressure wall cannot occur. Thus, a substantial amount of dust cannot settle in the annulus surrounding the heating surface of the heat exchanger.

  In the case where the annular portion is filled with the hot gas containing dust proposed earlier, the pressure in the annular portion is kept somewhat lower than the internal gas. However, in the method of the present invention, the gas pressure in the annular portion is The annulus is filled with a quench gas so that it is equal to or somewhat higher than the gas pressure in the generator device and channel.

  The temperature of the gas without dust is preferably 200 to 350 ° C, more preferably less than 300 ° C.

  Dust-free gas is part of the gaseous product of the gasifier device from which the dust has been removed downstream of the gasification reactor, for example, the dust-free product gas obtained in the solids removal section. Is preferred. This dust-free product gas is also preferably used as a quench gas, so it is advantageous to combine the supply of dust-free gas to the annular space and the supply of quench gas to the cooling channel. I understood. In a preferred embodiment, the means for supplying quench gas preferably comprises a gas exhaust opening for supplying quench gas to the cooled channel and a gas exhaust opening for supplying quench gas to the annular space. It has been found that robust and reliable operation can be achieved by providing sufficient openings in the means for supplying the quenching gas. Given the pressure level of the quenching gas and the pressure level in the cooling channel, those skilled in the art could easily determine the area of these openings.

  In a preferred embodiment, any slide points present in the cooling channel are given hermeticity to the hot product gas guided in the cooling channel. In the method of the present invention, the pressure compensation function is separated from the slide point function. This is because the quenching gas used for pressure compensation is introduced into the annular portion from the quenching device between the gasification reactor and the quenching tube.

  Thus, the pressure compensation function is also separated from the other two functions that can be attributed to the slide point, the expansion function and the assembly separation function. Preferably, one or more gas barriers are connected between each pressure wall and each cooled component to eliminate the secondary function of compensating for the substantial differential axial expansion of the component at the slide point. It can be placed in a region where the differential expansion between is small.

  Furthermore, it is beneficial to fill the annulus present in the syngas cooler with a cooled hot gas, the annulus being limited by at least one heat exchanger surface and a pressure wall surrounding it, Further, the annular portion filled with the quenching gas is closed.

  The present invention also provides an elongated gasification reactor vessel that can be used in the process described above, comprising a gasifier device and a coaxially arranged cooling channel through which the dust of the gasifier device passes. The cooling channel for discharging the contained hot gaseous product from the reactor; and means for supplying quench gas to the hot gaseous product containing dust at a location downstream of the gasifier device; It also relates to the elongated gasification reactor vessel provided with means for supplying dust-free gas to the annular space between the reactor vessel wall and the cooling channel. Preferably, the means for supplying the quenching gas comprises a gas discharge opening for supplying the majority of the quenching gas to the cooling channel and a gas discharge opening for supplying a small amount of the quenching gas to the annular space. The means for supplying the quenching gas is usually a hole (exit opening), and its size determines the amount of gas sent to the quenching pipe and the annular part, respectively.

  Preferably, the cooling channel comprises a slide point that is hermetically sealed for hot gases guided in the cooling channel.

  Preferably, one or more slide points are provided in the cooling channel downstream of the quenching gas supply device. Such a slide point exists between the two cooling channel segments and / or at the end of the cooling channel. Preferably, an annular barrier for closing the annular space is arranged downstream of these slide points.

  Advantageously, another slide point is provided in the area of the connection path, preferably this slide point is associated with an enlarged part of the pressure mantle so that it can better perform the function of assembly separation in the area of the slide point. It is done.

  As mentioned above, in known carbon gasification plants, the heating surface of at least one heat exchanger surrounded by a pressure wall is connected downstream of the cooling channel in order to further cool the gas (product gas). The In this connection, a slide point is provided between the cooling channel and the heating surface of the heat exchanger, and an annular barrier for closing the annulus downstream of the slide point is upstream or downstream of the heating surface of the heat exchanger. It is beneficial to be placed in

  Usually, several heating surfaces connected one after the other on the gas side are used, which are surrounded by the same pressure wall. Preferably, pressure compensation is performed between the internal gas in the heating surface of the heat exchanger and the surrounding annulus with hot gas containing dust pre-cooled in the heating surface of the heat exchanger. . Due to the substantially lower temperature compared to the temperature in the region of the hot gas guide channel, no secondary flow can occur, so that a large amount of dust settling in the annulus can no longer occur.

  Where there are multiple heat exchanger heating surfaces, it is beneficial to insert an airtight slide point between at least two adjacent heating surfaces.

The invention will now be described with reference to the accompanying drawings. In the attached drawing:
FIG. 1 shows one embodiment of a carbon gasification plant where the gasifier device is located in a first pressure vessel (gasification reactor) and the heating surface of the heat exchanger is a second pressure vessel (syngas cooling). The two pressure vessels are connected through an ascending connection path (so-called duct); and FIG. 2 shows another embodiment corresponding to FIG. (Duct).

  The gasification plant shown in FIG. 1 comprises a gasification reactor 1, a connecting duct 2 and a synthesis gas cooler 3. The gasification reactor 1 includes an elongated pressure vessel 4 oriented in the vertical direction, and cooling channels 5 and 7 and a quenching gas supply device 6 are arranged in the pressure vessel 4. The gasifier apparatus 8 is supplied with a carbonaceous raw material such as pulverized coal. The quenching gas Q is supplied at 9 to the quenching gas supply device 6. The rapidly cooled hot product gas HG flows through the cooling channel portion 7 downstream of the quench gas supply device 6. This cooling channel comprises a cooling surface. Preferably, these cooling surfaces are bundles of conduits through which cooling water flows. A preferred cooling surface is a membrane wall as described, for example, in U.S. Pat. No. 4,859,213.

  A gas barrier 10 is provided at the lower end of the gasification reactor 1. Furthermore, the slag S is discharged at the lower end 11 of the gasification reactor 1. The pressure vessel 4 comprises a lower part 4a and an upper part 4b having an angled flange 4c. A pressure mantle 12 is connected to it. The synthesis gas cooler 3 includes a pressure vessel 13 composed of three vessel portions 13a, 13b, and 13c. The pressure vessel portion 13 includes a flange 13 d that is angled downward, which forms the connection path 2 together with the flange 4 c and the pressure mantle 12. In the gas cooler 3, for example, when viewed in the direction in which the high-temperature gas HG flows, there are three heat exchanger heating surfaces 14 arranged one above the other. Although only the heating surface is shown schematically, it may for example have the form of a heating surface with a cooled gas guiding mantle 14a and a straight or bent inner tube 14b. In the illustrated embodiment, these two upper heating surface gas guiding mantles 14 a are connected together to form a gas guiding mantle 15, which is guided through an airtight slide point 16 for lower heating surface gas guiding. Connected to the mantle 17.

  The connection between the cooling channel portion 7 and the gas guiding mantle 15 is made via a hot gas guiding channel 18. The hot gas guide channel 18 has a curved portion 18a extending into the pressure vessel 4, a straight portion 18b extending through the pressure mantle 12 and the flange 13d, and its last portion formed as a gas deflection chamber 18c. .

  The gas guide channel 18 is provided with a slide point 19 at its inlet end, and this slide point 19 enables sliding movement with respect to the quench pipe 7, and this quench pipe 7 has an enlarged portion 7a at its outlet end. Prepare. This enlargement is shown schematically as a simple conical shape.

  The opposite ends of the cooling channel portion 7 and the gas guide channel 18 are provided with compensator holders 20 and 21, between which a ring compensator 22 extends so that the slide point 19 is hot exiting the quench tube. Airtight against hot gas. In the connection path 2 in the region of the pressure mantle 12, another slide point 23 is provided between the two parts S 1 and S 2 of the gas guide channel 18. This portion S1 has an enlarged portion at its outlet end. The slide point 23 corresponds to the slide point 19 in the configuration.

  Another slide point 24 is provided between the outlet end of the gas guide channel 18 arranged in the gas cooler 3 and the inlet to the gas guide mantle 15. This slide point 24 is slid in that the enlarged portion 15a is not located at the outlet end of the gas guide channel 18 but at the inlet end of the guide mantle 15 when viewed in the direction of gas flow. Points 19 and 23 are different in configuration. The slide point 15 matches the slide point 24 in its configuration.

  It is possible to arrange the enlarged parts of the slide points 19 and 23 also on other gas guiding elements. Similarly, at the slide points 16 and 24, this enlargement can also be provided downstream of the inlet end of the section guiding the gas.

  As shown in FIG. 1, the gasification reactor 5, the cooling channel portion 7, the gas guide channel 18, the gas guide mantle 15, and the guide mantle 17 are annular portions defined by the pressure vessel 4, the pressure mantle 12, and the pressure vessel 13. Surrounded by 25. This annular part is on the one hand limited by the annular barrier 10 in the gasifier device 1, and two partial annular parts 25 a and 25 b by an annular barrier 26 arranged between the slide point 24 and the upper heating surface 14. It is divided into.

  Since the slide points 19, 23 and 24 are airtight with respect to the hot gas containing dust guided in the internal gas, the hot gas containing dust can enter the annular portion 25a during normal operation. Can not.

  The annular portion 25 a is filled with the quenching gas Q for pressure compensation between the internal gas of the gasification reactor 1, the cooling channel portion 7, and the gas guide channel 18. The quenching gas Q exits the quenching gas supply device 6 through the outlet opening 27 and enters the annular portion 25a. The shape of the outlet opening 27 is selected so that the pressure in the annular portion 25a is equal to or somewhat higher than the gas pressure of the hot gas in the internal gas. Since the quench gas enters the annulus at a temperature (eg, 250 ° C.) substantially lower than the temperature of the hot gas (eg, 900 ° C.) in the gas guide channel 18, dangerous heating of the respective pressure walls cannot occur. . Because the quenching gas is free of dust, no dust settling can occur.

  The annular portion 25b downstream of the annular barrier 26 is filled upward from the rear by the already partially cooled high temperature gas exiting from the lower end of the gas guide mantle 17 cooled to, for example, 300 to 250 ° C.

  The annulus 25b is still filled with dust but substantially colder gas so that no secondary flow can occur due to the hot gas flow rise and subsequent cooling.

  As shown in dashed lines in FIG. 1, the pressure mantle 12 can include an enlarged portion 12a that allows entry into the slide point 23 via the inlet opening 12b for inspection.

  An annular barrier 26 can be located downstream of one of the heating surfaces 14 and thus the annular portion 25a can be enlarged. It is also conceivable to place an annular barrier 26 on the slide point 24.

  The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in that the connection path between the gasifier 1 and the gas cooler 3 is not raised but lowered. Two general configurations according to FIGS. 1 and 2 with a connecting path 12 that rises or falls are also known from FIGS. 1 and 2 of US Pat. No. 4,859,214. Also in the embodiment of FIG. 2, the enlarged portion 12a can be provided. Other connecting paths are also possible, for example horizontal or curved paths.

  Thus, in both embodiments, the annulus 25 defined between the component and the pressure wall is not filled with hot gas exiting the quench tube at any point, but is filled with cold gas, i.e., on the one hand. In the form of a quenching gas Q, the other is filled with a hot gas that has already been cooled. The filled spaces are separated from one another by barriers to avoid short circuits between the quenching gas and the cooled hot gas. The position of the annular barrier can be changed as seen from the direction of hot gas flow.

  FIG. 3 shows the quench supply device 6 in more detail. This quench supply device is a modified quench supply device, as shown in FIGS. 3 and 3a of US-A-4859213. The change is that an opening 27 is added through which quenching gas can enter the annular space 25. FIG. 3 also shows a part of the membrane wall 45 of the cooling channels 5, 7, an opening 53 for supplying quench gas to the cooling channels 5, 7 and a part of the supply conduit 9.

1 illustrates one embodiment of a carbon gasification plant, wherein the gasifier device is disposed in a first pressure vessel (gasification reactor) and the heating surface of the heat exchanger is in a second pressure vessel (syngas cooler). Arranged and connected through a connecting path (so-called duct) in which these two pressure vessels rise. Another embodiment corresponding to FIG. 1 is shown, comprising an inclined connection path (duct). The rapid cooling supply device 6 is shown in more detail.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification reactor 2 Connection duct 3 Syngas cooler 4 Pressure vessel 6 Quench gas supply device 7 Cooling channel 8 Gasifier device 10 Gas barrier 12 Pressure mantle 13 Pressure vessel 14 Heat exchanger heating surface 15, 17 Gas guide Mantle 16, 19, 23, 24 Slide point 18 Hot gas guide channel 20, 21 Compensator holder 22 Ring compensator 25 Annular part 26 Annular barrier HG High temperature product gas Q Quenching gas S Slag

Claims (8)

  A method for gasifying a solid carbonaceous feedstock, wherein the gasification is performed in an elongated gasification reactor vessel, the vessel being a cooling channel coaxial with a gasifier device, through the cooling channel. The cooling channel for discharging the gasification device hot dusty product from the reactor, and quenching the dusty hot gas product at a location downstream of the gasifier device. Means for supplying gas, and at a rate sufficient to prevent hot gas containing dust from flowing from the cooling channel to the annular space, the dust-free gas and the wall of the reactor vessel. The gasification method for supplying an annular space between the cooling channels.   The method of claim 1, wherein the pressure in the annular space is equal to or higher than the pressure in the cooling channel.   The method according to claim 1 or 2, wherein a temperature of the dust-free gas is 200 to 350 ° C.   4. The method according to any one of claims 1 to 3, wherein the dust-free gas is part of a gaseous product of the gasifier device that has removed dust downstream of the gasification reactor.   The method of claim 4, wherein the dust free gas is part of the quench gas.   6. The method of claim 5, wherein the means for supplying a quench gas comprises a gas discharge opening for supplying a quench gas to a cooling channel and a gas discharge opening for supplying a quench gas to the annular space.   An elongated gasification reactor vessel, with a gasifier device and a coaxially arranged cooling channel, through which the hot gaseous product containing gasifier device dust is removed from the reactor. Said cooling channel for discharging and means for supplying quenching gas to a hot gaseous product containing dust at a location downstream of said gasifier device, and for removing dust-free gas from said reactor vessel The elongated gasification reactor vessel is also provided with means for feeding an annular space between a wall and the cooling channel. The reaction according to claim 7, wherein the means for supplying a quench gas comprises a gas discharge opening for supplying a quench gas to the cooling channel and a gas discharge opening for supplying a quench gas to the annular space. vessel.