WO2013120917A1

WO2013120917A1 - Process and device for fixed-bed pressure gasification of solid fuels

Info

Publication number: WO2013120917A1
Application number: PCT/EP2013/052910
Authority: WO
Inventors: Bernd Meyer; Martin Gräbner
Original assignee: Technische Universität Bergakademie Freiberg
Priority date: 2012-02-13
Filing date: 2013-02-13
Publication date: 2013-08-22
Also published as: IN2014DN06625A; RU2607662C2; AP2014007913A0; ZA201406700B; RU2014137020A; CN204111704U; KR102054353B1; AU2013220406A1; AU2013220406B2; DE102013202356A1; KR20140131358A; UA112216C2

Abstract

The invention relates to a process and a device for fixed-bed pressure gasification of solid fuels having an increased performance and also a widened usage spectrum of solid fuels. For this purpose, the process is conducted in such a manner that, using a fixed-bed pressure gasifier with a feed of the coarse-grain solid fuels and with a gas take off, both at the top of the fixed-bed pressure gasifier, with a rotary grid and with ash discharge at the bottom of the fixed-bed pressure gasifier, with an adjustable feed for first gasification agent for a non-slagging gasification using the rotary grid of the fixed-bed pressure gasifier, wherein critical minimum values for the steam-oxygen ratio can be set, having a heap of the fixed bed above the rotary grid, in addition to the first gasification agents fed using the rotary grid, second gasification agents for a slagging gasification are injected via at least one gasification agent nozzle extending into the upper region of the fixed-bed heap.

Description

Process and apparatus for fixed bed pressure gasification of solid fuels

The invention relates to a method and a device for fixed bed pressure gasification of solid fuels with increased performance and broader range of solid fuels. Inventive method and apparatus allow the gasification of coals with higher fines and / or additional fine-grained and dust-like fuels to gasify.

The gasification of coarse solid fuels, d. H. of coarse-grained coals and / or carbonaceous solids having grain sizes greater than about 5 mm and less than about 100 mm, is preferably carried out in a fixed bed by the method of fixed bed pressure gasification FDV, also known as fixed bed dry bottom gasification. The fuels are introduced by means of pressure locks overhead in the fixed bed pressure carburetor. In the fixed bed (actually moving bed), which extends over the height of the fixed-bed pressure gasifier, the following zones form ideally from top to bottom: drying zone, pyrolysis zone, gasification zone, oxidation zone and ash zone. The ashes are discharged at the bottom of the carburetor through a rotary grate, which also serves to supply the gasification agent. The raw gas exhaust is located at the top of the fixed bed pressure carburetor.

The gasification agents consist essentially of technical oxygen and water vapor. The latter is added in excess to limit the maximum temperatures in the oxidation zone to levels below or near the ash melt temperatures relevant to fixed bed pressure gasification, thus avoiding the formation of massive, malfunctioning ash agglomerates or slagging (non-slagging gasification). The quantitative ratio of water vapor and oxygen in the gasification agent is one of the most important variables for controlling the process. It is frequently used as steam-oxygen ratio (DSV), preferably in the units kg steam / m ³ (iN) oxygen (100 vol. ). Depending on the level of ash melting temperatures, minimum values between approx. 4 kg / m ³ (high-melting ash) and approx. 9 kg / m ³ (low-melting ash) are required. Although the excess steam increases the gas flow rates and the accumulation of fine grain, which is discharged with the raw gases through the raw gas outlet, but do not contribute to increase the reaction conversion. Although the values for the steam-oxygen ratio are adjusted to the ash melting temperatures and kept as low as possible (critical minimum values of the steam-oxygen ratio for a so-called "hot" mode of operation at the "slag limit"), considerable limitations result, in particular with respect to the maximum performance, the flowability of the bed and the dust discharge, see also / J. Schmalfeld: The refinement and conversion of coal, DGMK (2008), p. 31 1 /.

A thereby caused with, general disadvantage of fixed-bed pressure gasification is that the solid fuel to be gasified may contain only small proportions of fine-grained fuels with particle sizes less than about 5 mm and in particular dusty fuels with particle sizes less than about 1 mm. Otherwise, there are local accumulations of fine-grained material in a fixed bed with the result of non-regular, channel-like flows through the fixed bed, and high dust emissions, incomplete carbon sales in the ashes or slagging. These negative effects increase when using baking coal or briquetted lignite in different ways.

Of general disadvantage of the countercurrent principle are still the low raw gas outlet temperatures of the fixed bed pressure gasification. Ammonia, non-condensable higher hydrocarbons, phenols and tar oils, which are separated together with the discharged dusts in the water (tar-gas water-dust mixtures), are usually unwanted by-products. The raw gas outlet temperatures are dependent on the fuel input according to the overall heat balance of the process. They can not be actively increased with the exception of the intentionally arranged, incomplete heat exchange between gas and solid (eg lowered bed).

In order to comply with the required particle size spectrum of the coarse-grained fuels to be gasified, the extracted raw coal must be treated. In particular, coal is screened and / or scrubbed prior to gasification to separate the fine fines (coal fines), reduce ash levels and increase the quality of the solid fuels to be gasified. Often, the fines are less than 5 mm up to 50% of the unspiked, extracted coal. Since the separated coal fines can not readily be used to generate synthesis gases in fixed-bed pressure gasification, appropriate solutions have been sought.

According to EP10792A1 pellets are formed from the fine-grained fuels, which are surrounded by a non-baking coating layer. GB1435089A describes the preparation of a fine coal / ash / pitch mixture which is extruded into an extruder and forced out of the extruder directly into the gas space of the atmospheric fixed bed pressure carburetor. As a pelleting aid for coal fine grain also Bentonite proposed (US 4,773,919 B1). Alternatively, US Pat. No. 4,146,369 B1 proposes to expand the fixed-bed pressure carburetor upwards by a fluidized-bed gasifier and above it by an entrained-flow gasifier in which fine-grained and pulverulent fuels are to be usable. Also, a separate arrangement of fluidized bed or Flugstromverggasern for the processing of fine-grained or dust-like fuels is proposed, for. For example, in WO 1980/00974 A1, the gasification of a previously prepared fuel / hydrocarbon / water slurry in Flugstromvergaser.

DD 219 597 A1 discloses a process for the non-slagging gasification of coals in which the gasification agent feed is subdivided into a primary and a secondary feed. The main part of the gasification agent is separated from the grate to the primary gasification and the gasification fraction provided for the secondary gasification in a freely selectable, matched to the gasification material supplied in a known manner via the grate, the DSV should be down to the exclusive steam feed down. Overall, this is a non-slagging method of gasification with formation of fine-grained ash. According to the proposal, the gasifier must be operated with high DSV, so as not to exceed the ash melting point. The reason for this is the avoidance of slagging of the carburettor. Overall, the fine ash constituents should be transported quickly into the area below the Vergasungsmittelaustrittes to avoid an ash transport in the upper reactor sections and the ash discharge with the production gas. It should be noted that the proposal does not take into account the fundamental requirements of environmental protection, efficiency and operational safety. The predominant to complete supply of the gasification agent with nichtverschlackendem driving the carburetor in the higher areas of the bed inevitably leads to burning through the bed (channel breakthrough) and the mixing of incompletely reacted oxygen with the raw gas, so that deflagrations or explosions can occur with catastrophic consequences. Other reasons for the impracticability of the proposal are the incompleteness of the carbon turnover, i. the high carbon content of the ashes removed from the rotary grate, as well as the prevention of the landfill capacity of the ash.

A further procedural limitation of the non-slagging fixed-bed gasification according to the prior art relates to the fuel spectrum with regard to the bakeability of the coals. Although hard coal with stronger baking properties can be gasified, but require a mechanical stirrer in the top of the fixed bed pressure carburetor, making the process more complicated, prone to failure and more expensive.

So far, it has not been possible to find more cost-effective solutions for the elimination of the stirrer process. The other proposed solutions for the recovery of Fine fuels are technically complex and not economically viable. They could not prevail in practice. The fine coal must be used for another purpose (usually incineration) instead of gasification. Nevertheless, a large part of the fine coal is often not economically viable and must be deposited in the form of heaps.

It is therefore an object of the invention to develop a method for fixed bed pressure gasification with associated device that allow with the help of low process and plant engineering changes over previously known Festbettdruckvergasern to increase the performance of Festbettdruckvergaser to reduce the steam input, the range of use of fuels with respect to baking To broaden coals and coals with higher fines and / or additionally to ignite fine-grained and dust-like fuels.

According to the invention the object is achieved by a method for fixed bed pressure gasification of coarse solid fuels with oxygen and water vapor-containing gasification means of a Festbettdruckvergasers with a supply of coarse-grained solid fuels and with a gas outlet, both at the head of Festbettdruckvergasers, with a rotary grate and an ash discharge at the bottom of the fixed bed pressure carburetor, with an adjustable first gasification agent supply for non-gassing by means of the fixed bed pressure carburettor rotary grate, whereby critical minimum steam-oxygen ratio can be set, with a bed of fixed bed above the rotary grate;

wherein, in addition to and independently of the first gasification means supplied by means of the rotary grate, second gasification means for a gassing are injected via at least one gasification agent nozzle extending into the upper region of the fixed bed,

and wherein the second gasification agents are injected with steam-oxygen ratios of 0.5 to 4 kg / m ³ and gas outlet velocities of 20 to 120m / s.

According to the invention, second gasification agents for the gassing are fed to the fixed-bed pressure carburetor additionally and independently of the first gasification means supplied via the rotary grate for the non-gasifying gasification, wherein the second gasification agent is injected into the upper region of the bed of the fixed bed by means of gasification nozzles extending into the upper region of the fixed bed become. With the first gasification agents, the first non-slagging gasification with the ideal zone formation over the entire bed of the fixed bed (first drying zone, first pyrolysis zone, first gasification zone, first oxidation zone, first ash zone) and the second gasification means is the second slagging gasification with local vortex zones (Raceway ) Formation.

The critical minimum values for the steam-oxygen ratios (in units of kg of steam / m ³ (iN) oxygen (100 vol.%), Stated) of the first gasification agents for the "hot" mode of operation at the "slag limit" are the ash melting behavior of the adapted solid fuels adjusted. The adaptation is simplified in such a way that as defined as ash granulation takes place (softening and sintering of the ashes), without causing slagging and the formation of large slags that block the discharge, cf. / J. Schmalfeld: The refinement and conversion of coal, DGMK (2008), p. 31 1 /.

Advantageously, the second gasification agents are introduced into the upper half of the first gasification zone forming during the gasification, d. H. injected below the first pyrolysis zone forming during the gasification. Particularly advantageous is the injection of the second gasification agent in a vertical zone, which comprises a vertical extent of <1 m in the upper half of the first gasification zone below the pyrolysis zone. Particularly advantageously, the second gasification agents are injected in a vertical zone of the fixed-bed pressure gasifier which reaches at most 1 m above the tip of the rotary grate to 0.5 m below the surface of the bed of the fixed bed, preferably from 2 m above the top of the rotary grate to 1 m below the surface of the bed of the fixed bed.

According to an advantageous embodiment of the method according to the invention, the amount of injected oxygen of the second gasification agent is 0 to 50% of the total amount of oxygen supplied.

The injection of the second gasification agent with gas exit velocities of 20 to 120 m / s causes the formation of turbulent vortex zones in the form of voids in the fixed bed in front of the outlet openings of the gasification agent nozzles, in which carbon burns with oxygen (second combustion zones). The vortex zones in front of the nozzles are enveloped by a bed of coke, with which the excess water vapor of the first non-slagging and, if appropriate, the water vapor of the second slagging gasification reacts with a decrease in temperature (second gasification zones). The fact that the second gasification agent with steam-oxygen ratios with values of 0.5 kg / m ³ (iN) to 4 kg / m ³ , preferably from 0.5 to 3 kg / m ^{3 are} injected, it is achieved that the before the at least one ash released into the upper region of the packed bed immediately melts or sinters and accumulates in the coke bed at the edge of the fluidized zones (second slag zones). The molten or sintered ashes cool rapidly in the surrounding, colder coke bed and solidify and release their heat to the environment to enhance the endothermic second gasification processes. The formation of classical stratified zones does not take place during gasification with the second gasification agents.

For example, with the second gasification agents having steam-oxygen ratios of 0.5, average maximum temperatures of about 2,000 ° C. are reached in front of the gasification agent nozzles reaching into the packed bed, which results in the gasification of coals with ash melting points of 1,500-1,700 ° C. is advantageous. If the vapor / oxygen ratio of the second gasification agent is 3.0, average maximum temperatures of about 1,800 ° C. are reached before the gasification agent nozzles reaching into the packed bed. This is advantageous for the gasification of coals with ash melting points of 1,300-1,500 ° C.

It is advantageous if the gasification with the second gasification agents is carried out below the first pyrolysis zone. This ensures that degassed coke is available (higher cold gas efficiency compared to coal) and that the forming slag or sinter solidifies quickly in the surrounding, colder coke bed. On the other hand, as will be explained below, the ambient temperatures in the vicinity of the gasification agent nozzles reaching into the packed beds are approximately 800-1.100 ° C. so high that the solidified slags do not yet attain high strength. Slags adhering to the gasifying agent nozzles are detached from the bed moving downwards and transported further.

With regard to the temperatures of the coke bed in the first gasification zone, the following should be noted: The temperatures of the coke bed oscillate, due to the endothermic gasification reactions (initially without consideration of the second gasification processes) at approximately constant values of the so-called kinetic reaction end temperatures. These values are independent, mainly dependent on the reactivity of the cokes to water vapor. The range of reaction end temperatures ranges from about 800 ° C for highly reactive fuels (eg soft lignite) to 1,100 ° C for low-reactive fuels (eg low-volatile fuels) bituminous coal). It is therefore below the temperature range for the ash melting points of most fuels (about 1 .200 - 1 .500 ° C).

It is of particular advantage that the ashes liberated in the second gassing process immediately melt and suppress any channeling, since channel-like "burning through" of oxygen by the bed due to immediate slag formation is prevented are also quickly "closed" under slag formation. For this reason, the vortex zones can not, or only slightly, move away from the gasification agent nozzles, but meander at a roughly constant height in front of and above the gasification agent nozzles. The second gasification is thus locally limited and defined in height according to the arrangement of the outlet openings of the gasification agent nozzles. The meandering gas flow and the forming slag stabilize the fixed bed in the environment and above the gasification agent nozzles, so that, despite higher flow rates, the regular flow through the fixed bed is maintained.

The second slagging gasification leads to a homogenization of the flow through the entire fixed bed. The fine grain fractions of the coarse-grained fuels used can be increased without increasing the discharge of dust with the raw gases. The lower particle sizes of the coarse-grained solid fuels fed to the fixed-bed pressure carburetor on the top side can be reduced from approx. 5 mm to approx. 2 mm.

Due to the gasification with the second gasifying agents for slagging gasification, in addition to the coarse-grained fuels fine-grained and / or dust-like fuels (fine fuels) can be utilized in larger quantities, which would otherwise be fed to another use or landfill. For this purpose, the fine fuels are introduced in a concentrated form in the fluidized zones, the amounts of added fine fuels are at most so large that stoichiometric ensures a high degree of gasification in the fluidized zones.

Another essential advantage of the second gassing is that, in particular, the fine-grained and dust-like fractions of the fuels in the fluidized zones are gasified with coarsening of the ash / slag particles. The cooled, solidified slags contribute to the coarsening of the granulation in the entire fixed bed, especially in the first ash zone, and further to the "interlocking" stabilization of the fixed bed over the entire height are one of the main causes of high dust emissions, are suppressed or pushed back. The second gasification thus leads to a homogenization of the flow through the entire fixed bed. The fines of the fuels used can be increased without increasing the discharge of dust with the raw gases.

Dry to moist free-flowing fine fuels are advantageously given up by gravity from above into the bed of the fixed bed, approximately perpendicularly over the vortex zones forming before the gasification agent nozzles. When gravity enters the fuel slip, due to its own weight, from a arranged over the fixed bed pressure carburetor pressure lock via a metering in the carburetor. It is also possible, however, a gravity entry or a pressure entry from the side directly into the fixed bed above the vortex zones. Dry, pneumatically eligible fine fuels are also blown by means of pneumatic conveying via the gasification agent nozzles or from the side directly into the vortex zones. Finally, fine fuels are pumped in the form of slurries, either via the gasification agent nozzles or approximately perpendicularly over the fluidizing zones from above onto or into the bed of the fixed bed.

Alternatively, it is also possible to use a stuffing insert which takes place at the upper edge of the fixed bed, preferably within the first drying zone. Using a briquetting press, preferably a stamping press, fine-grained and / or dust-like fuels (fine fuels) are compacted in a mold channel, partially agglomerated or compacted and pressed directly into the bed. In contrast to the teaching of GB1435089A, the compacted fine fuels do not fall from above onto the fixed bed, whereby a disintegration of the compacted fine fuels followed by increased dust discharge in the raw gas is avoided. At the same time the penetrating strand compacted fine fuels is covered up by coarse-grained fuels, so that a direct blowing out of the abrasion is prevented. Another significant advantage of this entry system is the possible admixture of accumulating in the fixed bed pressure gasification tar-oil-solid mixture as agglomeration aids and the possible abandonment of a lock system for the entry of fine fuels. Due to the very high compression pressures of up to 150 MPa occurring in the molding channel, a virtually gas-tight seal between the pressurized gasification chamber and the surrounding area under atmospheric pressure is possible, so that a separate stringing system for the fine fuels can be dispensed with. This form of fine fuel input is independent of the operation of the second gasification and can also be used in non-operated or shut down second gasification agent nozzles. The second slagging gasification not only improves the fuel tolerance for increased fine grain and dust levels of the fuels, or allows additional input of fine fuels, but also increases the fuel tolerance to baking coals that would not be gasifiable without the use of a stirrer. The second combustion zones with their rapid temperature increases and high temperatures reduce the baking tendency of the coals and break up already formed coke networks. Due to the second gassing process, the use of the stirrer can be dispensed with in many cases.

It is also possible to carry out the second slagging gasification in the first pyrolysis zone or in the region of the transition from the first pyrolysis zone to the first non-slagging gasification zone. In this case, the ratio of the combustion and gasification reactions shifts more towards combustion reactions in the second slagging combustion zones. The raw gas outlet temperatures rise and the higher hydrocarbons, phenols and tar oils, which leave the fixed bed up, are split more thermally. The zone-related adjustment of the second slagging gasification is achieved by setting defined bed heights of the fixed bed. In this way, the raw gas outlet temperatures and the quality of the raw gas (methane content, unwanted secondary components, etc.) can be adjusted.

The gasification agent nozzles are designed as water-cooled gasification agent mixture nozzles (in the case of oxygen and water vapor as second gasification agents) or as water-cooled multi-component nozzles (in the case of the combined fine fuel feed). They can be both non-cranked (pipe nozzles), as well as cranked (crops), with the crop nozzles on the tubular nozzle shaft of the cranked nozzle head sits.

The gasification agent nozzles are guided through the cylindrical outer jacket or double jacket of the fixed bed pressure gasifier. The non-cranked gasification nozzles are aligned radially and horizontally or deviating from the radial and horizontal alignment with angles of attack of <45 ° in all directions adjustable. Preferably, the nozzles are radially and 10 to 20 ° aligned against the horizontal inclined downwards. This proves to be advantageous in avoiding the penetration of solids into the interior of the nozzles and in the formation of the vortex zones. In the case of the use of cranked gasification nozzles, the Nozzle shanks approximately horizontally aligned and the nozzle heads analogous to the above-mentioned angle of the pipe nozzles.

The second gassing is carried out in a limited altitude zone in the upper part of the bed of the fixed-bed pressure gasifier. The lower limit is given by ensuring a sufficiently large, vertical minimum distance to the underlying oxidation zone. This distance is> 0.5 m, preferably> 1 m. The vertical minimum distance to the top of the rotary grate is thus> 1 m, preferably> 2 m. It is necessary for the slag or sinter formed in the fluidized zone to solidify before entering the oxidation zone or the surface of the rotary grate. On the other hand, the gasification nozzles in the gasification zone are not exposed to high temperatures (<1 .100 ° C). The upper limit of the altitude zone results from the fact that a sufficiently high coverage of the gasification agent nozzles of> 0.5 m, preferably> 1 m, is ensured by the fuel bed of the fixed bed. At a dumping height of the fixed bed of 5 m, calculated from the top of the rotary grate, the vertical extent of the altitude zone for the second gasification can be a maximum of 3.5 m, preferably a maximum of 2 m. The gasification agent nozzles may be distributed over this height and over the cross section of the fixed bed pressure gasifier.

A further advantageous embodiment consists in selecting as short a height zone with a vertical extent of <1 m in the upper half of the first gasification zone, below the pyrolysis zone, as possible for the second gassing zone, so that the first non-gassing zone is uniform over the cross section is extended to the top.

In the event that the height of the bed of the fixed bed is changed between a maximum and a minimum level during operation of the fixed-bed pressure and the difference is more than 1 m, it is advantageous if alternatively two height zones of Festbettdruckvergasers are equipped with gasification nozzles, the lower altitude zone for the minimum level and the upper altitude zone for the maximum level of the fixed bed. The vertical minimum distance between the two altitude zones is more than 1 m. Processually, the two height zones are then optionally applied to the second gasification agents.

Advantageously, the second gasification agents are injected in an altitude zone either in a planar, horizontal plane, in a vertically stepped arrangement in the altitude zone, or in a conical altitude zone, which simulates the mushroom-shaped contour of the rotary grate or the contour of the bed surface. Preferably, the nozzle orifices of the gasification agent nozzles lie in a height zone either in a planar, horizontal plane, in a vertically stepped arrangement in the altitude zone, or in a conical height zone, which simulates approximately the mushroom-shaped contour of the rotary grate or the contour of the bed surface.

The gasification nozzles protrude with at least 10 cm free length (free nozzle lengths) into the gasification chamber of the fixed bed pressure gasifier. The near-wall gasification agent nozzles preferably protrude approximately 20 cm to 1 m deep into the gasification space of the fixed bed pressure gasifier. For larger, free nozzle lengths up to about 3 m, the gasification nozzles are held with tie rods from above.

In order to form spatially separated vortex zones, the lateral, horizontal distance between the outlet openings of the gasification agent nozzles should not be less than 50 cm. Preferably, the lateral, horizontal spacing of the outlet openings is 1 to 2 m. The vertical distance of superimposed outlet openings should be at least 1 m, but preferably greater than 2 m.

The second gasification agents are injected with steam-oxygen ratios between 0.5 and 4 kg / m ³ , preferably between 0.5 and 3 kg / m ³ . Although no steam is required in terms of process technology, a low vapor mixing is advantageous, so that steam is available without interruption as a purging gas for the gasification agent nozzles when the oxygen is switched off rapidly. Instead of steam and carbon dioxide or other inert gases can be used as purge gases.

The proportions of second to first oxygen can be varied within wide limits. In the case of a single gasifying agent nozzle 5 to 20 wt .-% of the total oxygen supplied as second oxygen are injected. The upper value can also be exceeded if larger quantities of fine fuels are to be utilized with a gasification agent nozzle. In the case of the formation of a second gasification zone over the entire cross section of the fixed-bed pressure gasifier and the additional gasification of fine fuels, up to 50% by weight of the total oxygen fed in can be injected as second oxygen. The lower the ash contents of the fuel input, the higher the proportion of second oxygen can be achieved.

The size of the slag or sintered pieces forming in the vortex zones in front of the individual gasification agent nozzles is limited by the fact that the oxygen loadings of the individual gasification agent nozzles are varied between the minimum and maximum load. In this case, the total amount of oxygen of the second gasification medium can be kept constant can be changed by changing the load distribution between the individual nozzles, or it can be varied over time, the total amount of oxygen.

Corresponding to the proportions of second oxygen (for the gassing) injected in addition to the first oxygen (for the non-gassing gasification), the thermal performances of the fixed bed pressure gasifier are increased approximately proportionally. It is of secondary importance, whether the fuel flow rate increased or whether additional fine fuels are registered. Together with the coarse-grained fuels or in addition to the coarse-grained fuels larger amounts of fine-grained and fine fuels can be gasified. Also, the fuel spectrum can be extended towards stronger baking coal without the use of a stirrer would be required. At the same time the specific steam input is lowered and the performance limit of the thermal carburetor performance is increased due to the improved flow conditions of the bed of the fixed bed.

According to the invention, the object is achieved by a fixed-bed pressure carburetor for the gasification of coarse-grained, solid fuels with oxygen and water vapor-containing gasification agents with a supply of coarse-grained, solid fuels and with a Rohgasabzug, both at the head of Festbettdruckvergasers, with a rotary grate and with a ash discharge at the bottom of the fixed bed pressure carburetor, with an adjustable feed for first gasification means for non-gassing by means of the rotary grate of the fixed bed pressure carburetor, wherein critical minimum values for the steam-oxygen ratio are adjustable, with a bed of fixed bed above the rotary grate, the fixed bed pressure carburetor being at the level of at least one, in the upper region projecting gasification agent for a comparison with the first gasification means additional and independent supply of second gasification agent for a non-closing having gasification ackende, wherein the at least one gasification agent nozzle is designed so that it allows the injection of second gasification agent with steam-oxygen ratios of 0.5 to 4 kg / m ³ , preferably from 0.5 to 3 kg / m ³ .

According to an advantageous embodiment of the solid-bed pressure gasifier according to the invention, the at least one gasification agent nozzle is designed such that the amount of injected oxygen of the second gasification agent is 0 to 50% of the total amount of oxygen supplied. Advantageously, the fixed-bed pressure gasifier has a plurality of gasification agent nozzles arranged in one or two planes for the second gasification means.

According to an advantageous embodiment, the fixed bed pressure carburetor has at least one entry for fine-grained and / or dust-like fuels (fine fuel input). The fine fuel entry is designed as a gravitational force or as a stuffing entry for compacted by briquetting fine fuels.

According to an advantageous embodiment of the fixed-bed pressure gasifier, the gasification agent nozzles are designed as water-cooled gasification agent mixture nozzles (in the case of oxygen and water vapor as second gasification agents) or as water-cooled multicomponent nozzles (in the case of the combined fine fuel feed). The gasification agent nozzles preferably protrude into the gasification space of the fixed bed pressure gasifier with at least 10 cm free length (free nozzle lengths).

The nozzle mouths of the gasifying agent nozzles are arranged according to an advantageous embodiment of the invention in a vertical zone either in a planar, horizontal plane, in a vertically stepped arrangement in the altitude zone, or in a conical altitude zone, which is approximately the mushroom-shaped contour of the rotary grate or the contour of the bed surface replicates.

The plant engineering design of the second slagging gasification is simple, robust and requires only small equipment technical adjustments of the known and proven Festbettdruckvergasers. These relate to the bushings for the gasification nozzles, and if necessary, the supply nozzles for the fine fuels. It proves to be of particular advantage that the second slagging gasification in existing fixed bed pressure gasification plants is set up, retrofitted and operated in stages (starting with a gasification agent jet) completely (with a complete set of gasification jet nozzles) or partially operated or decommissioned or retrofitted according to the requirements can be.

embodiment

With reference to accompanying drawings, an embodiment of the invention will be explained in more detail. Showing: Fig. 1 Schematic representation of a fixed bed pressure carburetor

Fig. 2 top view section A-A

Fig. 1 shows a Festbettdruckvergaser (1) and Fig. 2 is a sectional view of the plane A-A with a plan view.

At the top of the fixed-bed pressure gasifier is an entry (2) for coarse-grained, solid fuels and a raw gas outlet (30). At the bottom of the fixed-bed pressure gasifier (1), a rotary grate (5) for supplying first gasification means (6) for the non-gasifying gasification and an ash discharge (31) is arranged.

The fuel entry (2) opens in the upper part of the fixed bed pressure carburetor in a Einhängeschacht (28). In addition to the fuel input (2) for coarse-grained fuels, an entry (21) for fine fuels is arranged at the top of the fixed bed pressure gasifier (1). The fine fuel entry (21) opens into a drop tube (22) supported inside the attachment shaft (28), wherein the drop tube (22) is longer than the attachment shaft (28) and ends with a baffle (24) in the reaction space of the fixed-bed pressure gasifier (1). The fine fuel entry is inertizable with nitrogen (27).

The clear inside diameter of the fixed bed pressure carburetor (1) is 4 m and the height of the bed of the fixed bed (3), calculated from the top (4) of the rotary grate (5), an average of 6 m. It is limited by the connection shaft (28) for fuel distribution. The bed of the fixed bed (3) is ideally divided into the five layers from bottom to top: first ash zone (14), first oxidation zone (15), first gasification zone (16), first pyrolysis zone (17) and first drying zone (18).

At a height of 3 m above the tip (4) of the rotary grate (5) are a total of ten nozzles (7) for the supply of the second gasification means (8) for the gassing grafting evenly distributed over the outer jacket (9) of the fixed bed pressure carburetor (1 ) arranged.

Above the tip (4) of the rotary grate (5), in the upper level of the first gasification zone (16) and above the first pyrolysis zone (17), the container casing has feed nozzles (7). The feed ports (7) in the upper level of the first non-slagging gasification zone (16) are equipped with gasifying agent nozzles (12) sufficient for supplying second gasifying means (8) for slagging gasification sufficient to enter the gasification zone.

The sockets (7) are numbered in the section A-A clockwise with IM to / 10 /. They are guided through the outer, pressure-bearing container wall (10) and the inner steel shell (1 1). A total of six of the ten nozzles (7) are equipped with gasification nozzles (12). The gasification agent nozzles (12) are designed as tube nozzles, radially aligned and inclined 15 ° downwards towards the horizontal. They protrude 50 cm into the bed of the fixed bed (3). The mouths (13) of the gasification agent nozzles (12) terminate in the upper region of the first non-slagging gasification zone (16).

The nozzle (7) directed into the first drying zone (18) is arranged with a briquetting press (32) for the supply of compacted or briquetted fine fuels (21).

The fixed bed pressure carburetor thus constructed is operated as follows:

In the Festbettdruckvergaser (1) 58 th non-baking, coarse-grained hard coal (2) with an ash content of about 35 wt .-% (tr.), A water content of about 5 wt .-% (tr.), An ash melting point of about 1 .400 ° C and a grain size of about 5 - 100 mm gassed at a total pressure of about 30 bar. The hard coal (2) are introduced from above into the fixed-bed pressure carburetor (1). The raw gas (29) leaves the fixed bed pressure carburetor (1) through the raw gas outlet (30), while the ash (31) by means of the rotary grate (5) is pulled down. About the rotary grate (5), the first gasification means (6) are supplied. The amount of the first oxygen of the first gasification agent is 12,000 Nm ³ / h (based on pure oxygen), the vapor-to-oxygen ratio is on average 4.5 kg / Nm ³ .

The amount of second oxygen of the second gasification agent (8) is a total of 3,200 Nm ³ / h (based on pure oxygen), the steam-oxygen ratio 0.8 kg / Nm ³ .

The gasification nozzles (12) of the numbers / 3 /, / 4 /, / 8 / and / 9 / are each with 600 m ³ / h (iN) oxygen and the gasification nozzles (12) of the numbers IM and 161 with 400 m ³ / h (iN) oxygen is applied. The second gasification agent flow with Flow velocities of 70 m / s (gasification nozzles (12), numbers 181, 141, 181 and / 9 /) and 50 m / s (gasification nozzles (12), numbers IM and / 6 /). Before the mouths (13) vortex zones (19) form. In front of the adjacent gasification nozzles (12), numbers 181 and 141 as well as numbers 181 and / 9 /, two larger, contiguous regions (20) of the vortex zones (19) are formed.

Approximately centrally above the contiguous regions (20) of the vortex zones (19) of the adjacent gasification nozzles (12), numbers 181 and 141 and numbers 181 and / 9 /, fine fuels (21) by gravity via a downpipe (22) or the Stopfeintrag means the briquetting press (32) registered.

At the lower outlet opening (23) of the downpipe (22) are baffles (24), under which cavities (25) in the bed of the fixed bed (3) form, in which the fine fuels (21) can flow freely. The drop tube (22) is supported on the attachment slot (28) with holders (26). The vertical distance of the outlet openings (23) to the gasification agent nozzles (12) is 2 m. The drop tube (22) is rendered inert with a small amount of nitrogen (27).

The fine fuels (21) come from the same hard coal (2). The grain size of the fine fuels (21) is 0-2 mm, the ash content is 40 mass% (tr.), The water content is 5 mass% (tr.). Both downpipes (22) are each 5.5 t / h fine fuels (21) supplied.

The thermal performance of the fixed-bed pressure gasifier (1) is increased in the present example by applying the solution according to the invention by about 25%. In addition, the co-gasification of fine fuel is made possible for the first time to a considerable extent.

reference numeral

1 fixed-bed pressure carburetor

2 entry gasification substances

3 fixed beds

4 tip

5 rotating grate

6 first gasification agents

7 nozzles

8 second gasification agent

9 container wall

10 pressure-bearing container wall

1 1 inner steel jacket

12 gasification nozzles

13 mouths of the gasification nozzles

14 first ash zone

15 first oxidation zone

16 first gasification zone

17 first pyrolysis zone

18 first drying zone

19 vortex zone

20 contiguous area

21 fine fuels

22 downpipe

23 outlet opening

24 baffle

25 cavities

26 bracket

27 Nitrogen

28 hanging bay

29 raw gas

30 raw gas outlet

31 ash

32 briquetting press

33 agglomeration aids

Claims

claims

1 . Process for the fixed-bed pressure gasification of solid fuels with oxygen and water vapor-containing gasification means, by means of a Festbettdruckvergasers with a supply for coarse-grained, solid fuels and with a gas outlet, both at the head of Festbettdruckvergasers, with a rotary grate and with a ash discharge at the bottom of Festbettdruckvergasers with an adjustable feed for first gasification means for a non-gasifying gasification by means of the rotary grate of the fixed-bed pressure gasifier, wherein critical minimum values for the steam-oxygen ratio can be adjusted, with a bed of the fixed bed above the rotary grate, characterized

that in addition to and independently of the first gasification means fed by means of the rotary grate, second gasification means for a gassing are injected via at least one gasification agent nozzle extending into the upper region of the fixed bed,

- And that the second gasification agent with steam-oxygen ratios of 0.5 to 4 kg / m ³ and gas outlet velocities of 20 to 120m / s are injected.

2. The method according to claim 1, characterized in that the second gasification agent are injected into a vertical zone of the fixed bed pressure carburetor, the maximum reaches from 1 m above the top of the rotary grate to 0.5 m below the surface of the bed of the fixed bed.

3. The method according to claim 1 or 2, characterized in that coarse-grained, solid fuels are entered with a grain size greater than 2 mm in the fixed bed pressure carburetor.

4. The method according to any one of claims 1 to 3, characterized in that fine-grained and / or dust-like fuels are added to the vortex zones, which form before the Vergasungsmitteldüsen, with the amount of added fine-grained and dust-like fuels is at most so large that stoichiometric ensures a high degree of gasification in the vortex zones.

5. The method according to any one of claims 1 to 4, characterized in that the second gasification means are alternatively injected into two height zones each having a vertical extent of <1 m, which have a vertical minimum distance from each other of 1 m and corresponding to the maximum and the minimum bed height of the fixed bed of Festbettdruckvergasers, each in the upper half of the first gasification zone, below the pyrolysis zone are arranged.

6. fixed-bed pressure carburetor for gasification of coarse-grained, solid fuels with oxygen- and water-vapor-containing gasification agents, with a supply of coarse-grained, solid fuels and with a crude gas, both at the head of Festbettdruckvergasers, with a rotary grate and with a ash discharge at the bottom of Festbettdruckvergasers, with an adjustable feed for first gasification means for non-slagging gasification by means of the rotary grate of the fixed-bed pressure gasifier, wherein critical minimum values for the steam-oxygen ratio are adjustable, with a bed of fixed bed above the rotary grate, characterized

in that the fixed-bed pressure carburetor has, at the level of the upper region of the fixed bed bed, at least one gasifying agent nozzle projecting into the upper area for the supply of second gasifying means for slagging gasification,

- That the at least one gasification agent nozzle is designed such

- And that it allows the additional and independent injection of second gasification agent with steam-oxygen ratios of 0.5 to 4 kg / m ³ and with gas outlet velocities of 20 to 120m / s.

7. fixed bed pressure carburetor according to claim 6, characterized in that the fixed-bed pressure carburetor has a plurality of arranged in one or two planes gasification agent nozzles.

8. fixed bed pressure carburetor according to claim 6 or 7, characterized in that the fixed-bed pressure carburetor has at least one entry for fine-grained and / or dust-like fuels (fine fuel input).

9. fixed bed pressure carburetor according to claim 8, characterized in that the fine fuel input is configured as a gravitational force entry or as a stuffing entry for compacted by briquetting fine fuels.

0. Festbettdruckvergaser according to any one of claims 6 to 9, characterized in that the gasification agent nozzles are designed as water-cooled Vergasungsmittel- mixture nozzles (in the case of oxygen and water vapor as the second gasification agent) or as water-cooled multi-component nozzles (in the case of the combined fine fuel supply). 1 . Fixed bed pressure carburetor according to any one of claims 6 to 10, characterized in that the gasification agent nozzles protrude with at least 10 cm free length (free nozzle lengths) in the gasification chamber of the fixed bed pressure carburetor.