DE202017107810U1 - Pressure-resistant burner tip - Google Patents

Abstract

Pressure-resistant burner tip with internal cooling for a pilot or gasification burner for producing synthesis gas under a pressure of up to 200 bar, the burner tip being formed as a one-piece, hollow-cylindrical and preferably conical end piece (2) of an outer burner tube (1),
characterized in that
- In the conical end piece (2) under its inner and outer circumferential surface turbulent flow through coolant channels (4, 5) are arranged, between the inner coolant channels (4) and the outer coolant channels (5) a non-traversed by coolant channels support ring (6) is
The cross-sectional contours of the coolant channels (4, 5) lie parallel to the lateral surface contours of the end piece (2), the cross-sections of the coolant channels (4, 5) being constant along the flow path in the end piece (2),
- The inner and outer coolant channels (4, 5) near the surface and in semicircle or quadrant channel sections in a plurality of transverse and equidistant flow planes, wherein meandering flow channels through the 180 ° channel arc (7) between the flow planes to reverse the circumferential flow direction under the inner and outer lateral surface are formed.

Description

 The invention relates to a flameproof burner tip with an internal cooling for a gasification burner for the production of synthesis gas under a pressure up to 200 bar, wherein the burner tip is formed as a one-piece, annular and preferably conical end of an outer burner tube.

Synthesis gas is recovered from organic solid, liquid or gaseous fuels, such as coal and coal suspensions of varying degrees of coking, cokes of various organic materials or petroleum / natural gas in an autothermal partial oxidation reaction at high pressure, generally up to 80 bar, and high temperatures up to 2000 ° C , The gasification reaction may, for example, take place in an entrainment gasification reactor containing one or more gasification furnaces into which solid, liquid or gaseous fuels and oxygen are fed. In an entrainment gasification, it is common to arrange a starting burner (also referred to as a pilot burner or pilot burner) to build up pressure in the reaction space and ignite the fuel to be oxidized centrally in the head of the gasification reactor, surrounded by several gasification burners (also referred to as dust burners, main burner or simply burners) is. Alternatively, starting burners are integrated in the gasification burners. The flow from the burners in a "Top Burner Arrangement" flow stream reactor is directed downwards. The fuel is pneumatically fed as fuel-feed gas dense stream the gasification burners. In the flame zone of the burners, the reactants are heated to reaction temperature and in the resulting outgoing flow cloud of carbon and hydrogen contained in the fuel are reacted together with the supplied oxygen in partial oxidation reactions and other side reactions to a synthesis gas. The gasification process and the basic design of entrained flow gasification reactors, for example, in the DE 41 09 231 C2 described.

In the gasification burners fuel, oxygen and optionally steam are supplied to the reaction space and mixed intensively so that they react as completely as possible under reducing conditions to a H ₂ - and CO-rich synthesis gas. The gasification temperature is in the entrained flow gasification of coal dust between 1400 ° C and 1700 ° C, the gasification pressure usually 40-80 bar. An increase in the gasification pressure, for example up to 200 bar, leads to higher conversions in the reactor.

Gasification burners for entrained-flow gasifiers are exposed to a strong heat of more than 1000 ° C. in the area of the burner parts that directly dip into the reaction space. Another stress arises from the contact of the burner mouth with the resulting in the gasification reaction corrosive reaction products, which arrive due to the inevitable backflow to the burner mouth. The channel and guide elements of the pulverized coal burners are additionally exposed to high abrasive stresses by the coal dust and as a result of the supply of oxygen in the flame zone, the metal parts of the burner flowed around are additionally stressed by an aggressive oxidizing atmosphere. A usual protective measure consists in the intensive heat dissipation from the burner mouth area by a water cooling of the burner. The heat dissipation can be supported by materials with high thermal conductivity. Despite all protective measures, a gasification burner must be made of heat- and corrosion-resistant materials, at least in the burner mouth area. For this purpose, especially good heat-conductive nickel-base alloys are used.

In the DE 10 2008 006 572 A1 a traditionally designed water-cooled burner for a gasification reactor is described, which conventionally manufactured according to the Pressure Equipment Directive with high wall thicknesses burner tip is made of a nickel-based alloy and which is protected in addition to the annular gap cooling the burner tubes at the burner mouth with a ceramic protective layer against the high temperature load in the reactor.

• – Die Kühlung der Brenner beruht auf einer Ringspalt-Wasserkühlung, die relativ große Kühlmittelmengen im Umlauf benötigt.
• – Aufgrund des fertigungsbedingten geringen Anteils an Stützstrukturen und der angestrebten geringen Wandstärken für einen effektiven Wärmeübergang sind die Brenner nur für geringe Auslegungsdifferenzdrücke zwischen Kühlsystem und Reaktor bzw. zwischen Kühlmittel und angrenzend zugeführten Vergasungsmedien geeignet.
• – Eine konventionelle Fertigung der Brennerspitzen ist kompliziert und unvermeidliche Schweißnähte an der Brennerspitze, die einer hohen thermischen Belastung ausgesetzt sind, verringern die Verschleißfestigkeit.

From the EP 1 102 627 B1 a burner is known which has an annular cooling water channel with protective coating only in the region of the burner mouth, wherein outside of the burner arranged helical cooling water pipes for the Kühlwasserzu- - are available. However, the burners and burner tips traditionally produced from semi-finished tube pipes have the following basic disadvantages:

• - The cooling of the burner is based on an annular gap water cooling, which requires relatively large amounts of coolant in circulation.
• - Due to the low production-related fraction of support structures and the desired low wall thicknesses for effective heat transfer, the burners are only suitable for low design differential pressures between the cooling system and reactor or between coolant and adjacent supplied gasification media.
• - Conventional manufacturing of burner tips is complicated and inevitable welds on the torch tip, which are subjected to high thermal stress, reduce the wear resistance.

A new way of burner protection describes the DE 10 2015 202 579 A1 in which a one-piece, generatively manufactured burner tip is proposed with minimized wall thicknesses, wherein increased heat dissipation from the burner tip as a result of maximizing the coolant wetted inner surfaces of the burner tip increased cooling effect is achieved, so that additional protective layers are not required. The support structure of the burner tip can be produced by means of SLM (Selective Laser Melting) or 3D printing. The disadvantage is the complexity of the inner structure with a variety of coolant channels and filigree support walls and the traditional, not thermally optimized coolant flow in parallel flow channels.

The invention has for its object to provide a generatively producible burner tip with internal cooling, which has a high pressure resistance, simplified structure and improved heat dissipation.

According to the invention the object is achieved by a burner tip with the characterizing features of the first claim. Advantageous embodiments of the burner tip are the subject of the other claims.

The proposed flameproof burner tip with an internal cooling for a pilot or gasification burner is designed such that are embedded in the hollow cylindrical, preferably conical end under its inner and outer circumferential surface turbulent flow through coolant channels, wherein between the inner coolant channels and the outer coolant channels not one of coolant channels traversed support ring is present. The lateral surface near cross-sectional contours of the coolant channels run parallel to the outer contour of the end piece, wherein the cross sections of the coolant channels along the flow path in the end piece are constant. The inner and outer coolant channels run near the surface in half or quarter circle channel sections in several transverse and equidistant flow planes. By means of 180 ° channel arc, a reversal of the flow direction in the circumferential direction takes place between the flow planes, so that meander-shaped flow channels are formed below the inner and outer circumferential surfaces. Such a further developed burner tip has the advantage that, despite a simple channel structure, a more intensive and uniform heat removal from the burner tip is achieved by heat conduction and convection than is known from the prior art. The particular and regular arrangement of the coolant channels with axial and tangential channel portions of constant pitch and constant cross section causes a secondary circumferential component to be added to the primary axial coolant flow in the torch tip, so that bidirectional coolant flows provide uniform and gapless cooling of the entire surface of the tail , whereby no local temperature peaks with increased wear occur.

The coolant channels have in comparison to the known traditional burner tips small cross-sections and are designed for a turbulent pipe flow. This forms the prerequisite for the inventive hydrodynamic optimization of the cooling of the burner tip by a high proportion of thermal inlet flow sections with not yet formed velocity profile is generated in the entire flow path through numerous 180 ° arc. Thermal inlet flow areas, in which a stable velocity profile builds up over the pipe cross-section, occur after discontinuities in the flow channel, such as, for example, after flow deflections. The thermal advantages of these inlet flows consist in thinner boundary layers, higher temperature gradients and thus higher heat fluxes, which are transferable to the coolant. In channel areas with a thermal inlet flow, there is a more intense heat transfer to the coolant than with a formed laminar or turbulent pipe flow. The advantage of inlet flows is deliberately used in the design of the proposed burner tip to improve the heat transfer to the coolant despite smaller channel cross-sections. With the optimized coolant guide in the burner tip, an improvement in the service life of the burner tip is achieved. At the same time, the consumption of coolant is reduced by small channel cross sections.

The burner according to the invention has a very high compressive strength up to 200 bar due to the small channel cross-sections and the internal structure of the burner tip according to the invention. This is characterized by near-surface parallel channel sections and thereby achievable constant wall thicknesses between the channels, the stabilizing support ring, a continuous adaptation of the channel shape to the outer contour, thereby realizable constant outer wall thicknesses and the uniform distribution of Umlenkbögen that form discontinuities in the wall structure over the circumference and the height of the burner tip. A flameproof burner tip makes it possible to increase the coolant pressure, to reduce the circulating coolant quantity and to design the coolant system accordingly cost-saving.

Such a structured burner tip can be produced by way of a "rapid manufacturing" production process with additive or additive Manufacturing be created. Examples include selective laser melting (SLM), selective laser sintering (SLS), selective heat sintering (SHS) or electron beam melting (EBM). With a generative manufacturing method, the formation of the non-classical coolant channel structure is made possible, the production cost is significantly reduced compared to conventional production. A generative manufacturing process also makes it possible to integrate additional temperature sensor probes into the torch tip. With additional temperature control points in the burner tip, not only the wear hazard, but also the burning behavior of gasification burners can be monitored during the operating time.

In the following, the invention will be explained using the example of a burner tip for a gasification burner for the production of synthesis gas in an extent necessary for understanding the solution. The accompanying drawings represent:

1 : Longitudinal view of the burner tip

2 : 3D illustration of the coolant channels

The pressure-resistant burner tip with internal cooling is intended for a pilot or gasification burner for the production of synthesis gas under a pressure of up to 200 bar and a reaction temperature of up to 1900 ° C. The burner tip is as a one-piece, hollow cylindrical and preferably conical tail 2 an outer burner tube 1 educated. At the media outlet is the tail 2 preferably with an approximately semicircular estuary contour 3 fitted. Into the conical tail 2 are under its inner and outer circumferential surface turbulent flow through coolant channels 4 . 5 embedded with small cross-sections to promote a turbulent channel flow, wherein between the inner coolant channels 4 and the outer coolant channels 5 a non-traversed by coolant channels support ring 6 is available. The support ring 6 in the central jacket area of the tail 2 forms the relevant structure of strength. For connection to the outer burner tube 1 has the tail 2 a neck ring 10 with a smaller radius than the adjoining end piece part with the coolant channels 4 . 5 on. The burner tube 1 can with the neck ring 10 be firmly welded or releasably screwed in a known manner. The cross-sectional contours of the coolant channels 4 . 5 adapt to the outer contour of the tail 2 continuously, ie the mantle near contours of the channel cross-sections are parallel to the lateral surface contours of the tail 2 so that the material thickness between the coolant channel and tail surface is approximately the same at each location. For example, material thicknesses between 0.5 and 2.5 mm may be suitable for compressive strengths of about 50 bar to 250 bar pressure difference between the reactor pressure and coolant pressure. The flow cross sections of the coolant channels 4 . 5 are along the flow path in the tail 2 constant, so that neither local pressure nor velocity gradients in the coolant system of the tail 2 occur. Due to the desired turbulent flow form of the coolant, the pressure loss in the burner tip is higher than in conventional burners. The pre-pressure in the coolant supply line is in the range of 5 to 10 bar.

The inner and outer coolant channels 4 . 5 run near the surface and in half or quarter circle channel sections in several equidistant transversal flow planes (perpendicular to the end piece longitudinal axis), whereby by means of 180 ° channel arc 7 between the flow planes for the reversal of the circumferential flow direction parallel running meandering flow channels are formed under the inner and outer circumferential surface. The transversal, quarter or semicircular channel sections of the coolant channels 4 . 5 between the 180 ° channel arch 7 have constant distances from each other. Coolant channels 4 . 5 and 180 ° channel bends are recessed as cavities during the layered manufacturing process. To avoid structural weaknesses in the tail 2 are the 180 ° channel arch 7 in the inner coolant channels 4 opposite the 180 ° channel bend in the outer coolant channels 5 in the exemplary embodiment offset by 90 ° in the circumferential direction. For the staggered arrangement of the channel arch 7 Different variants come into consideration with other offset angles, but they do not mean inventive alternatives.

With the channel design described is a uniform structure in the tail 2 created, which positively influences the pressure resistance and also ensures a uniform cooling of the burner tip surfaces.

To connect the burner tip to the cooling system are the axially from the tail 2 led out fittings 8th the coolant channels 4 . 5 with strands of a per se known cooling tube winding (not shown) in a section above the end piece 2 connected outside or inside the outer burner tube 1 is arranged, wherein the tube winding to compensate for thermal expansion has spacings between the windings. Through the pipe winding, the coolant from the media connection side of the burner along the burner tube 1 fed to the burner tip and also returned from it to an external coolant treatment device that is not subject the proposed solution. The connection between the fittings 8th and the tube winding may be fixed or detachable for ease of maintenance. The embodiment shows a channel structure of the tail 2 with fittings 8th for two coolant inlets and two coolant returns, in the illustrated embodiment, each channel strand between inlet and return a half-shell of the tail 2 cools. Accordingly, the tube winding is designed as a four-strand winding, ie with four parallel tube coils.

The arrangement of the coolant channels 4 . 5 offers the possibility of having at least one channel 9 is provided for receiving a temperature sensor in the axial direction in the tail, the near the surface of the mouth or on a coolant channel 4 . 5 ends in the mouth area. Straight channels 9 for temperature sensors can be found in the material webs between the opposing channel arch space. These channels 9 are used as additional cavities during burner tip production along with the coolant channels 4 . 5 educated. After burner pre-assembly, one or more probes are inserted into the channels as needed 9 inserted. Unused channels 9 are closed on the surface to prevent the penetration of corrosive gases or particles. Are the 180 ° channel arc offset from transversal plane to transversal plane, as in the 2 is shown, no continuous material web is usable, so that the channels 9 suitable for sensors in the support ring 6 between the inner and outer coolant channels 4 . 5 are to be arranged in order to avoid the crossing of coolant channels and the associated sealing problems. Of particular interest for process control is the temperature at the burner mouth near the flame zone. Therefore, it is advantageous if one or more channels 9 close to the outer mouth contour 3 extend. In the case of several temperature sensors along the mouth circumference of the tail 2 it is possible to detect from the temperature distribution irregularities in the flame formation at the burner mouth or its degree of wear. To measure the coolant temperatures, it may also be appropriate to have a first channel 9 on or in a coolant channel for the coolant supply line and a second channel 9 to end at or in a coolant return line. The T measuring points are then arranged directly on the channel or immerse in the coolant flow and detect the coolant temperature without delay.

To adapt the properties of the tail 2 can the massive support ring in the basic version 6 in the toroid between the inner and outer coolant channels 4 . 5 have their own structuring during the manufacture of the tail 2 is produced. These may be, for example, partial cavity structures for reducing thermally induced stresses in the end piece 2 or structures for additional media channels or sensors for process monitoring. In 1 such cavity structures are indicated by dashed lines by way of example. It is also possible to access the inner and outer coolant channels 4 . 5 to provide only the minimum material thickness of, for example, 2.5 mm required to ensure compressive strength and the remaining toroidal core between the coolant channels 4 . 5 predominantly hollow.

Such a trained tail 2 can be economically produced only with a generative manufacturing process, such as selective laser melting, from a high temperature resistant metal alloy. Such manufacturing methods are well known and therefore need not be explained in detail.

During the use of the burner in the gasification process, a coolant, usually a treated cooling water, over the supply strands of the tube winding and the lugs 8th to the tail 2 conveyed, flows through the meander-shaped inner coolant channels 4 along the inner shell, flows in the mouth area in the outer coolant channels 5 and gets over the return strands of the tube winding 8th fed to the cooling water treatment device. In the coolant channels 4 . 5 there is a repetitive current deflection in the channel arc 7 whereby in each subsequent transverse channel section again a thermal inlet flow path with minimum temperature boundary layers and intense heat transfer from the outer surfaces is formed on the coolant, which have a higher cooling effect than known solutions.

LIST OF REFERENCE NUMBERS

1

burner tube

2

tail

3

mouth contour

4

Coolant channels (inner)

5

Coolant channels (outer)

6

support ring

7

duct bend

8th

Extension piece for pipe winding

9

channel

10

neck ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4109231 C2 [0002]
• DE 102008006572 A1 [0005]
• EP 1102627 B1 [0006]
• DE 102015202579 A1 [0007]

Claims (6)

Pressure-resistant burner tip with internal cooling for a pilot or gasification burner for the production of synthesis gas under a pressure of up to 200 bar, the burner tip being in the form of a one-piece, hollow-cylindrical and preferably conical end piece ( 2 ) of an outer burner tube ( 1 ), characterized in that - in the conical end piece ( 2 ) under its inner and outer circumferential surface turbulent flow through coolant channels ( 4 . 5 ), wherein between the inner coolant channels ( 4 ) and the outer coolant channels ( 5 ) a support ring (not crossed by coolant passages) 6 ), - the close-to-surface cross-sectional contours of the coolant channels ( 4 . 5 ) parallel to the lateral surface contours of the end piece ( 2 ), wherein the cross sections of the coolant channels ( 4 . 5 ) along the flow path in the end piece ( 2 ) are constant, - the inner and outer coolant channels ( 4 . 5 ) run close to the surface and in half or quarter circle channel sections in a plurality of transverse and equidistant flow planes, wherein by means of 180 ° channel bend ( 7 ) between the flow planes for reversing the circumferential flow direction meandering flow channels are formed under the inner and outer circumferential surface. Burner tip according to claim 1, characterized in that the 180 ° channel arc ( 7 ) in the inner coolant channels ( 4 ) with respect to the 180 ° channel bends in the outer coolant channels ( 5 ) are preferably offset by 90 ° in the circumferential direction. Burner tip according to claim 1, characterized in that the axially out of the end piece ( 2 ) led out connectors ( 8th ) of the coolant channels ( 4 . 5 ) are connected to strands of a coolant tube winding in a portion above the burner tip. Burner tip according to claim 1 or 2, characterized in that at least one channel ( 9 ) for temperature sensors in the axial direction within the support ring ( 6 ) is arranged and close to the surface of the mouth contour ( 3 ) or on a coolant channel ( 4 . 5 ) ends. Burner tip according to claim 1, characterized in that the support ring ( 6 ) a minimum material thickness required to ensure compressive strength to the coolant channels ( 4 . 5 ) and in the remaining ring core is at least partially hollow or has a structuring. Burner tip according to one of the preceding claims 1 to 6, characterized in that the end piece ( 2 ) is made of a high temperature resistant metal alloy by a generative manufacturing method such as Selective Laser Melting.

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