Reactor for partial oxidation of carbonaceous feedstock

Abstract

The invention relates to a reactor, in particular an entrained-flow gasifier, for producing synthesis gas by partial oxidation of a carbonaceous feedstock. The reactor includes a reaction space, a cooling space, and a gas channel fluidly connecting the reaction space and the cooling space. The gas channel has a gas inlet region adjacent the reaction space and a gas outlet region adjacent the cooling space. The cooling medium is supplied through the gas channel. According to the invention, in the direction of flow of the syngas to be cooled, the gas channel has a first region and a second region connected thereto, the first region having a constant diameter and the second region having a diameter that expands in the direction of flow of the syngas to be cooled.

Description

TECHNICAL FIELD

[0001] The present invention relates to a reactor for the production of synthesis gas by partial oxidation of a carbon-containing feedstock. The invention particularly relates to the gas passage between the reaction space and the cooling space of such a reactor. The invention is particularly characterized by an improved management of the synthesis gas to be cooled during its transfer from the reaction space to the cooling space. BACKGROUND

[0002] The partial oxidation of carbon-containing gaseous, liquid or solid fuels with oxygen is a method for the production of synthesis gas, which is commonly used for large-scale industrial production. Synthesis gas is a gaseous mixture comprising hydrogen and at least one carbon oxide (carbon monoxide and / or carbon dioxide). In an entrained flow gasification, a carbon-containing feedstock, an oxidizing agent such as oxygen and optionally a moderator (e.g. steam and / or carbon dioxide) are supplied via a feedstock feed system to a reaction space (also referred to as combustion space) having a burner. The above-mentioned media react with each other and form a hot raw synthesis gas / primary synthesis gas. Typical reaction temperatures are between 1300°C and 1500°C, and the pressure is up to 100 bar.

[0003] The cooling of the raw synthesis gas takes place in a second step downstream of the reaction in the reaction space. Depending on the process concept and the feedstock, a distinction is made in principle between two different cooling concepts. Firstly, the heat is transferred indirectly to a cooling medium in a waste heat boiler to produce steam, and secondly, the heat is transferred directly to a cooling medium using a quench cooler. The latter is also referred to in the industry jargon as "quenching". The further purification of the cooled raw synthesis gas is usually achieved by means of a scrubber and subsequently optional further treatment steps.

[0004] In the case of so-called submerged quenching, the outlet of the reaction space is usually directly connected to a gas duct which is immersed in the cooling medium, which gas duct leads the hot gas from the reaction space into a water reservoir in which the hot gas is cooled as it flows through the water reservoir. Such a system is described, for example, in US 2010 / 0325957 A1, US 2013 / 0189165 A1 and WO 2017 / 102945 A1.

[0005] In the case of free quenching, the hot gas from the reaction space is directly introduced into the cooling space (quenching space) via a guiding element, for example a guiding tube, and water is injected into the cooling space via one or more nozzles. Such a system is described, for example, in US 2007 / 0051043 A1 and US 2009 / 0007487 A1.

[0006] In the case of quenching tubes, the cooling liquid is introduced via a nozzle system into a gas stream directed in the tube at high speed, whereupon the gas stream flows into a widened quenching space for direct cooling with the cooling medium. Such a system is described in DD 215 326.

[0007] An important aspect of the cooling of the hot synthesis gas from the reaction space into the cooling space is the flow distribution, and thus also the mass and heat transfer. If recirculation flows occur in the case of a sudden transition from the outlet region of the reaction space to the cooling medium supply region, water droplets from the multiphase region can be transported back into the hot reaction space. The "multiphase region" is understood to mean the region in which the cooling medium is added. The cooling medium is in liquid form before the gasification takes place by means of the hot synthesis gas. If the water droplets that are transported back come into contact with very hot regions, for example regions of more than 800°C, they can cause thermal stresses in these regions, which lead to damage to the materials used. The materials can be, for example, refractory bricks or metallic materials suitable for high temperatures.

[0008] If cooling water that has not been specially purified, which can contain alkali and alkaline earth metal compounds, is used as cooling medium, boiling or gasification residues of these metal compounds can come into contact with the hot surfaces mentioned above. Sodium compounds, for example, can damage refractory bricks based on aluminum oxide at high temperatures. The droplets do not necessarily need to be produced by atomization of the cooling medium. It can be sufficient to form droplets even if the cooling liquid, which contains dissolved gases, is rapidly degassed as a result of temperature fluctuations in the cooling space. This is particularly true when the cooling medium used is completely or partially a scrubbing liquid from a downstream gas scrubber. This scrubbing liquid is saturated with components of the synthesis gas.

[0009] Another possibility for the formation of droplets can also include a relatively high heat transfer from the hot synthesis gas to the cooling medium in the region in which the cooling medium is added. SUMMARY

[0010] It is a general object of the present invention to at least partially overcome the above-mentioned disadvantages and problems of the prior art.

[0011] It is a further object of the present invention to configure the transition region from the reaction space to the cooling space in a reactor for the partial oxidation of carbon-containing feedstock in such a way that it is possible to avoid the return of the cooling medium from the cooling space to the reaction space, in particular in the form of droplets.

[0012] The independent claims help to achieve at least partially at least one of the above objects. The dependent claims provide preferred embodiments which help to achieve at least partially at least one of the above objects.

[0013] The terms "have", "comprise" or "include" and the like do not exclude the possibility that there are additional elements / elements, components etc. The indefinite article "a" does not exclude the possibility that there are a plurality of the respective elements.

[0014] The object of the present application is achieved at least in part by a reactor for producing synthesis gas by partial oxidation of a carbon-containing feedstock, the reactor comprising:

[0015] (a) a reaction space having a burner and having a feedstock feed system for supplying a feedstock and an oxidizing agent to produce synthesis gas in the reaction space;

[0016] (b) a cooling space comprising a synthesis gas outlet and a cooling medium outlet, wherein the cooling space is configured for cooling the synthesis gas by direct cooling with a cooling medium;

[0017] (c) a gas channel fluidically connecting the reaction space and the cooling space, the gas channel comprising a gas inlet region adjacent to the reaction space and a gas outlet region adjacent to the cooling space, wherein a cooling medium feed is provided in the region in which the gas channel is located.

[0018] According to the application, the gas channel has, in the flow direction of the synthesis gas to be cooled, a first region and a second region connected to the first region, wherein the first region has a constant diameter and the second region has a diameter that expands in the flow direction of the synthesis gas to be cooled.

[0019] The hot synthesis gas stream in the gas outlet region of the reaction space, which is the same as the gas inlet region of the gas channel, first passes through the first region of the gas channel having a constant diameter. Here a turbulent flow profile is formed, so that at the end of this first region a recirculation zone is terminated. In the flow direction of the synthesis gas to be cooled, following the end of the first region is a second region having an expanding / diverging diameter. In this context, "expanding / diverging" is understood to mean that the diameter increases, in particular continuously, from the beginning of the second region in the flow direction of the synthesis gas to be cooled towards the end of the second region. A suitable widening angle / expansion angle of the expanding second region can be determined or estimated by, for example, CFD calculations or fluid mechanics theory. The spatial widening of the second region in the direction towards the cooling space ensures further effective prevention of recirculation flow. The edge regions of the flow are also slowed down. This is associated with low mass and heat transfer.

[0020] The respective diameter of the gas channel is understood in particular as the passable diameter of the gas channel for the synthesis gas to be cooled. Thus, the respective diameter is in particular proportional to the freely passable cross section of the gas channel.

[0021] The flow of synthesis gas in the reactor according to the application in principle enters the gas channel from the reaction space, passes through the gas channel and then enters the cooling space. Thus, the flow direction of the synthesis gas to be cooled follows the following spatial sequence:

[0022] - the reaction space;

[0023] - a gas inlet region of the gas passage;

[0024] - a gas passage;

[0025] - a gas outlet region of the gas passage; and

[0026] - a cooling space.

[0027] The cooling medium is supplied in a region of the gas passage. In other words, the synthesis gas to be cooled first comes into contact with the cooling medium in the gas passage. Such a gas passage is often also referred to as a "quench tube".

[0028] Optionally, a hole is provided in the gas outlet region of the gas passage. As a result, a spray of cooling medium is generated in the gas outlet region of the gas passage, resulting in an intensive / adequate mixing of the cooling medium and the synthesis gas to be cooled in the cooling space of the reactor. The actual main cooling of the synthesis gas then takes place in the cooling space of the reactor.

[0029] The carbon-containing feedstock, also referred to as fuel, can be a gaseous, liquid and / or solid hydrocarbon mixture. Other examples include coal, biomass or municipal waste. All carbon-containing feedstocks suitable for partial oxidation to produce synthesis gas are in principle suitable.

[0030] The synthesis gas comprises, inter alia, hydrogen and carbon monoxide.

[0031] The cooling medium is preferably water.

[0032] The oxidizing agent is preferably air, oxygen-enriched air or pure oxygen. Suitable oxygen sources include air separation plants and / or electrolysis cells.

[0033] The feedstock feed system can also optionally be used to supply a moderator for controlling the exothermic partial oxidation reaction. The moderator can be steam and / or carbon dioxide. Carbon dioxide can be separated from the cooled raw synthesis gas as an unwanted reaction product and recirculated as a moderator to the reaction space of the reactor.

[0034] The cooling space comprises a synthesis gas outlet and a cooling medium outlet. The synthesis gas outlet, also referred to as a cold gas outlet, is used to extract the mixture of cooled synthesis gas and gasified cooling medium. The cooling space usually has a fill level of condensed cooling medium in its sump region. In order to control this fill level, condensed (excess) cooling medium is continuously extracted from the cooling space of the reactor.

[0035] The preferred embodiment of the reactor is characterized in that the first region of the gas passage is configured as a cylindrical region and the second region of the gas passage is configured as a region that expands conically.

[0036] Thus, the gas channel has a circular cross-section at each location of the first and second region. The second region of the gas channel is in particular configured to expand conically in the flow direction of the synthesis gas to be cooled. That is to say, the diameter of the second region is at its smallest at the interface with the first region. At this location / interface, the diameter of the second region in particular corresponds to the diameter of the first region. At the same time, the diameter of the second region is at its largest at the interface with the cooling space.

[0037] A preferred embodiment of the reactor is characterized in that the expanding diameter of the second region is characterized by an expansion angle a, wherein the expansion angle a has a magnitude of 1 ° to 20°, preferably 2° to 10°.

[0038] The expansion angle describes the angle which defines the deviation from the straight first / second region having a constant diameter. CFD calculations have revealed that the above-mentioned range of 1 ° to 20°, preferably 2° to 10°, leads to an optimal reduction of the flow velocity of the synthesis gas to be cooled in the edge region of the flow / stream. This reduction leads to low thermal stresses of the downstream reactor region, in particular of optional downstream flow guiding elements. The interaction with such liquid films generated in the gas channel is also reduced when using flow guiding elements to generate liquid films in the gas channel.

[0039] A preferred embodiment of the reactor is characterized in that the first region of the gas channel has a diameter di and a length li, wherein the length ratio of li to di (li:di) has a value of 1 to 10.

[0040] The ratio of the length li of the first region, also referred to as inflow region, to the diameter di is advantageously 1-10, since there is already a partially turbulent flow with a slower edge profile and any recirculation zone from the first region ends here.

[0041] A preferred embodiment of the reactor is characterized in that the gas channel has a third region which is arranged upstream of the first region in the flow direction of the synthesis gas to be cooled, and wherein the third region has a diameter which converges in the flow direction of the synthesis gas to be cooled.

[0042] In order to prevent the occurrence of pressure drops and to reduce inflow turbulence, the transition from the reaction space to the first region of the gas channel can have a diameter which converges in the flow direction of the synthesis gas to be cooled. The third region of the gas channel is in particular configured as a conically converging region. The end of the third region which is adjacent to the first region in the flow direction of the synthesis gas is preferably of a diameter di which thus corresponds to the diameter di of the first region of the gas channel.

[0043] A preferred embodiment of the reactor is characterized in that the free end of the second region of the gas channel is connected to a metallic flow guide element which extends within the gas channel and which extends towards the cooling space in the flow direction of the synthesis gas to be cooled.

[0044] The presence of the flow guide element following the second region of the gas channel in the flow direction of the synthesis gas effects the formation of a liquid film on the wall of the gas channel, so that an effective and uniform cooling of the synthesis gas already within the gas channel can be achieved. The flow guide element can also be referred to as a flow guide plate.

[0045] The flow guide element is preferably cooled by a cooling medium located at its back side.

[0046] The cooling medium feed and the flow guide element are preferably arranged such that the liquid cooling medium, in particular cooling water, cools the back side of the flow guide element during the cooling water supply. This effectively reduces the material stress on the metallic flow guide element.

[0047] The supply of the cooling medium to the gas channel preferably takes place via an annular gap, wherein the annular gap is formed at least partially by the flow guide element and a cooling medium feed system of the reactor.

[0048] The cooling medium feed system of the reactor comprises a nozzle, in particular a quenching nozzle, which injects the cooling medium into the gas channel via at least one opening in the gas channel. The cooling medium initially flows through an annular gap which is formed at least partially by the flow guide element and the cooling medium feed system. The cooling medium feed system comprises a cooling medium source which is fluidically connected to the gas channel.

[0049] In the downstream region in the gas flow direction, the flow guide plate can have a curvature or a bend, i.e. its angle with respect to the wall of the gas channel changes. In particular, this angle with respect to the wall of the gas channel decreases. As a result, the raw gas stream, which is slowed down in the outer region and still only to a small extent cooled, contacts the water film which forms on the wall of the gas channel and flows down along the inner wall of the gas channel without any flow interruption.

[0050] A preferred embodiment of the reactor is characterized in that, in order to reduce its thermal load, the surface of the flow guide element is provided with a ceramic protective coating or a metallic welded cladding.

[0051] In addition to the active cooling by the cooling medium, this measure further reduces the thermal stress on the flow guide element.

[0052] A preferred embodiment of the reactor is characterized in that the wall of the second region of the gas channel is formed from a refractory material suitable for high temperatures, in particular from a material based on aluminum oxide.

[0053] The reactor is preferably configured as an entrained-flow gasifier. BRIEF DESCRIPTION OF DRAWINGS

[0054] The application will now be more precisely described by way of working examples with the aid of the accompanying drawings, which are not intended to limit the application in any way. The drawings are not drawn to scale.

[0055] In the drawings:

[0056] Figure 1 is a schematic view of the essential parts of the reactor according to the application which are essential to the application. DETAILED DESCRIPTION

[0057] Figure 1 shows a cross-sectional view of a reactor according to the application, which shows in particular essential parts of the gas channel 1 of a reactor according to the application which are essential to the application.

[0058] The reactor comprises a reaction space 6 in which synthesis gas is produced by partial oxidation of a carbon-containing feedstock. Adjacent to the reaction space 6 is a gas channel 1 which leads in a lower region to a cooling space (not shown). The lower end of the gas channel (not shown) comprises an aperture which ensures sufficient mixing of the cooling medium and the synthesis gas to be cooled. The main portion / majority of the cooling of the synthesis gas takes place in the cooling space, the gas channel 1 essentially achieving the pre-cooling of the synthesis gas to be cooled.

[0059] According to Figure 1 , the synthesis gas to be cooled flows from top to bottom. That is to say, after production in the reaction space 6 it is passed through the gas channel 1 and subsequently fed to the cooling space (not shown). The cooled synthesis gas is extracted from the cooling space via a cooled gas outlet (not shown) together with the gasified cooling medium (here: cooling water) and is further processed.

[0060] At the bottom of the reaction space 6, the hot synthesis gas produced in the reaction space 6 enters a first region 2 of the gas channel 1. In order to prevent the occurrence of a pressure drop and to reduce the inflow turbulence, the transition from the reaction space 6 to the first region 2 can be conically converging. As shown, the first region 2 has a constant diameter dl over the entire length li. The diameter dl is determined such that the flow velocity of the synthesis gas to be cooled is in the range from 10 m / s to 50 m / s. A small diameter dl is advantageous because it reduces the length li of the first region. The ratio of the length li to the diameter dl is advantageously 1 to 10 because this forms a flow with at least partially turbulent flow with a slow edge profile and any recirculation zones from the upper portion of the first region 2 end in the lower portion of the first region 2.

[0061] Downstream of the gas channel in the direction of flow of the synthesis gas, the gas channel has a second region 3 which widens conically, through which the flow of synthesis gas widens, so that the flow in the edge region of the gas channel 1 is further slowed down. The widening of the flow proceeds to such an extent that the synthesis gas flow does not detach from the edge region of the gas channel 1 and thus no recirculation zone is formed. The widening angle a shown can be determined by CFD calculations. The widening angle a is preferably in the range from 1° to 20°, particularly preferably in the range from 2° to 10°. The reduction of the flow velocity in the outer region of the gas channel achieves lower thermal stresses on the flow guide elements 4, 5 connected to the second region 3, and further downstream reduces the interaction with the liquid film 8 formed by the cooling medium.

[0062] The liquid film 8 is produced by the supply of a cooling medium (also referred to as quenching medium) via the cooling medium feed system 7 (quenching nozzles). The flow direction of the cooling medium through the cooling medium feed system 7 is indicated by the arrows shown.

[0063] The second region 3 of the gas channel which widens conically is formed by refractory bricks of the refractory lining 10, which are based on aluminium oxide, for example. The flow guide elements 4, 5 which are fixed to this second region 3 extend with a similar widening angle, preferably also in the range from 1° to 20°.

[0064] The flow guide elements 4, 5 have two regions 4 and 5. They differ in terms of the angle with respect to the edge region of the gas channel 1, i.e. their widening angle with respect to the first region 2 of the gas channel. The flow guide elements 4, 5 together with the inner part of the cooling medium feed system 7 form an annular gap 9 through which the cooling medium flows, so that this annular gap is cooled sufficiently. This prevents corrosion processes of the metal parts of the cooling medium feed system 7. There is necessarily a slight discontinuity at the transition from the second region 3 to the flow guide elements 4, 5. At this point, locally very limited recirculation turbulence can form in the synthesis gas flow. However, these recirculation turbulences do not extend to the contact point between the second region 5 of the flow guide elements and the cooling medium which forms the water film 8.

[0065] The second region 5 of the flow guide elements is formed such that the synthesis gas flow which is slowed down and cooled to a small extent in the outer region of the gas channel 1 contacts the water film 8 which flows down the inner wall of the gas channel 1 without any flow interruption. This can be achieved because the widening angle of the second region 5 of the flow guide elements differs from the widening angle of the first region 4 of the flow guide elements, as shown.

[0066] The cooling medium feed system 7 is configured such that the cooling medium is deflected / diverted therein. The cooling medium feed system is separated from the refractory lining 10 by a metallic separation element 11 which also forms part of the reaction space 6 of the reactor. Thermal stresses on the refractory lining 10 are also reduced by the heat dissipation from the flowing cooling medium of the cooling medium feed system. The metallic separation element 11 which forms part of the cooling medium feed system 7 is also used to connect the flow guiding elements 4, 5 to the second region 3 of the gas passage. This connection can be achieved by, for example, a welded connection.

[0067] List of reference signs

[0068] 1 gas passage

[0069] 2 first region of the gas passage

[0070] 3 second region of the gas passage

[0071] 4 flow guiding element (first region)

[0072] 5 flow guiding element (second region)

[0073] 6 reaction space

[0074] 7 cooling medium feed system (quench nozzle)

[0075] 8 water film

[0076] 9 annular gap

[0077] 10 refractory lining

[0078] 11 metallic separation element

Claims

1. A reactor for producing syngas through partial oxidation of a carbonaceous feedstock, the reactor comprising: (a) A reaction space (6) having a burner and a feed system for supplying feedstock and oxidant to produce syngas in the reaction space (6); (b) A cooling space including a syngas outlet and a cooling medium outlet, wherein the cooling space is configured to cool the syngas by direct cooling with a cooling medium; (c) A gas channel (1) fluidly connecting the reaction space and the cooling space, the gas channel including a gas inlet region adjacent to the reaction space and a gas outlet region adjacent to the cooling space, wherein a cooling medium feed is provided in the region where the gas channel (1) is located. Its features are, In the flow direction of the syngas to be cooled, the gas channel (1) has a first region (2) and a second region (3) connected to the first region, wherein the first region (1) has a constant diameter and the second region (3) has a diameter that expands along the flow direction of the syngas to be cooled.

2. The reactor according to claim 1, characterized in that, The first region (2) of the gas channel (1) is constructed as a cylindrical region, and the second region (3) of the gas channel is constructed as a region that expands in a conical shape.

3. The reactor according to any one of the preceding claims, characterized in that, The expansion diameter of the second region (3) is characterized by an expansion angle α, wherein the size of the expansion angle α is 1° to 20°, preferably 2° to 10°.

4. The reactor according to any one of the preceding claims, characterized in that, The first region (2) of the gas channel has a diameter d1 and a length l1, wherein the ratio of diameter d1 to length l1, l1:d1, is 1 to 10.

5. The reactor according to any one of the preceding claims, characterized in that, The gas passage (1) has a third region arranged upstream of the first region in the flow direction of the synthesis gas to be cooled, wherein the third region has a diameter that converges along the flow direction of the synthesis gas to be cooled.

6. The reactor according to claim 5, characterized in that, The third region of the gas channel is constructed as a conical converging region.

7. The reactor according to any one of the preceding claims, characterized in that, The free end of the second region of the gas channel is connected to a metallic flow guide element (4, 5), which extends within the gas channel and toward the cooling space in the flow direction of the synthesis gas to be cooled.

8. The reactor according to claim 7, characterized in that, The flow guiding elements (4, 5) are cooled by a cooling medium located on their back side.

9. The reactor according to claim 7 or 8, characterized in that, The supply of cooling medium to the gas passage is carried out via an annular gap (9), wherein the annular gap (9) is formed at least in part by the flow guiding elements (4, 5) and the cooling medium feeding system (7) of the reactor.

10. The reactor according to any one of claims 7 to 9, characterized in that, The surface of the flow guiding element (4, 5) is provided with a ceramic protective coating or a metal welding coating in order to reduce the thermal load of the flow guiding element.

11. The reactor according to any one of the preceding claims, characterized in that, The wall of the second region (3) of the gas channel (1) is formed of a refractory material suitable for high temperatures, particularly an aluminum oxide-based material.

12. The reactor according to any one of the preceding claims, characterized in that, The reactor is configured as a fluidized bed gasifier.

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