NL7901452A - CENTRIFUGAL PUMP FOR CARBON POWDER, METHOD AND APPARATUS FOR GASIFICATION OF CARBON POWDER. - Google Patents

Description

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K 6988 MSP

Applicant: Shell Internationale Research Maatschappij B.V.,

Carel van Bylandtlaan 30, The Hague

Short designation: "Centrifugal pump for carbon powder as well as • method and device for gasification of carbon powder"

The invention relates to a centrifugal pump for feeding powder into a high-pressure space, comprising a feed and a rotor, the feed leading to the center of the rotor and the rotor one or more substantially radial passages perpendicular to the rotational axis which connect to said feed and are open at their outer end.

Such pumps are known from U.S. Pat. Nos. Ho. 2,822,097 »Ho. 3,182,825; Ho. ^ .0 ^ + 9.133 and Ho. 4.120Λ10 and function as a pendulum pump, i.e. the powder is thrown into a large vessel by the high speed rotor, where the speed of the particles is reduced to zero. The powder is thereby fed via the feed to the center of the rotor and moves in the rotor outwardly under the influence of the centrifugal force through the radial passages of the center of the rotor and finally leaves these passages via the open end with a radial and tangential velocity component.

These pumps are used, for example, to feed powdered solid fuel into a high pressure vessel; such as coal powder which is fed through a vessel to a reactor connected to the vessel for the partial combustion of coal. A pressure of usually at least 10 atm prevails in the vessel. and the pump serves to feed the coal powder into the vessel from atmospheric pressure against the differential pressure. Under these conditions, the velocity at which the particles leave the rotor is high, on the order of magnitude 7901452 * ·· «* 2 of 100 meters / sec. In tangential direction and 10 meters / sec. in radial direction.

The energy invested in this speed has so far not been used, which is a drawback. In addition, under certain circumstances, it may be disadvantageous that the powder particles undergo a temperature rise, due to the friction caused by rapid deceleration in the equipment described in the above patents.

The present invention aims to overcome these drawbacks and therefore proposes to enclose the rotor by a housing whose radial distance from the rotor increases in the direction of rotation to a point where the housing leads tangentially away from the rotor. The space thus obtained between the rotor and the housing ensures the best possible impulse retention of the medium that eventually leaves the pump, ie the powder particles retain as much as possible the initial force-15 velocity component in the said space and also the particles of entrained gas assume this speed as much as possible.

It is essential that from the point where the distance between the rotor and housing is minimal - seen in the direction of rotation - the space becomes larger as the rotor throws more powder into the space.

In the axial direction, the housing can adjoin the sides of the rotor on either side, and there can be left some space between the housing and the rotor and / or a seal between the housing and the rotor.

When some space is left between the housing and the sides of the rotor 25, gas supplies are preferably located in the housing, which open into the spaces between the housing and the sides of the rotor.

The advantage of this is that the powder entering these spaces is blown back into the space of the housing radially outside the rotor.

The housing can be provided with one or more gas supplies that open tangentially in the space around the rotor. The gas that can be injected or drawn in through these gas feeds is then accelerated by the powder particles. It will be clear that the incorporation of these gas feeds into the pump increases the controllability of the powder flow 7901452 • * 3, since there is a degree of freedom with regard to the amount of gas supplied as well as the initial pressure and speed of this gas.

Centrifugal pumps of the type according to the invention can be used for the supply of powdered solid fuel to a reactor for the partial combustion at high pressure of this powder, either because the pump is directly connected to a burner which ends in the reactor or because the pump doses the powder into a high-pressure fluidizing vessel from which the fluidized powder is fed to the burner.

Especially with reactors in which two burners are arranged diametrically opposite each other in the wall, it is important that both burners are always fed identically. Especially in this case, when the pump is connected directly to the 15 burners, it can be of great benefit to design the pump with a housing consisting of two identical halves, each enclosing half of the rotor, the radial distance of which the rotor increases in an equal manner to the point where the housing half leads tangentially away from the rotor. When each housing half is now connected to a burner, there is a high degree of certainty that both burners will be loaded equally.

It will be clear that the house can also consist of more than two identical parts.

An advantage of the direct connection of the burner (s) to the pump is that the speed of the powder particles is not reduced to zero on their way from the pump to the reactor (as in the case of the prior art mentioned above) ), so that the powder particles need not be accelerated again.

In order to effect a pressure rise of the gas-entrained by the powder, according to the invention, preferably, the or any part of the housing which diverts tangentially away from the rotor is designed as a diffuser.

7901452 k

As is known, in a diffuser the cross-section in the flow direction increases and the speed of the gas flowing through the diffuser decreases and the pressure increases.

The space in the pump between housing and rotor can have any suitable cross-sectional shape, for example a rectangular or a more rounded profile. It will be appreciated that the portion of the housing leading tangentially away from the rotor will have a cross-sectional shape that will gradually transition from that of said space to a circular one (if the cross-section of said space is not also circle-shaped) . If a diffuser is used, it can ensure the gradual transition.

The invention also relates to a method for the partial combustion of powdered solid fuel at elevated pressure, wherein the powder is fed either directly or via an intermediate vessel to the partial combustion reactor via a centrifugal pump according to the invention.

The exclusive right also extends to a device for the partial combustion of powdered solid fuel at elevated pressure, comprising a reactor in which one or more burners end, the burner (s) being either directly or via an intermediate vessel (s). ) connected to a pump according to the invention.

The invention will be explained in more detail below with reference to the accompanying drawing, in which:

Hg. 1 is a schematic representation of an axial cross-section through a centrifugal pump according to the invention;

Fig. 2 is a section according to plane II-II of FIG. 1;

Fig. 3 is a schematic of a "double" pump according to the invention, and

Fig. 4 is a schematic of a gas inlet pump according to the invention.

The centrifugal pump shown in Figures 1 and 2 comprises a flat slag-shaped housing 1 on a base 2 and provided with a diffuser-shaped discharge 3, a central inlet 4 and a central bearing housing 5 · 7901452 5

Inside the housing 1 there is a flat disc-shaped rotor 6, the axis of rotation of which J coincides with the axis of the feed H and with the axis of the bearing housing 5.

Three radial passages 10 run from the center 8 to the periphery 9 of the rotor, which in the center 8 connect to an axial bore 11 which runs from the center to the left side surface 12 of the rotor and connect to the supply U of the housing 1.

On the side of the right-hand side 13 of the rotor there is a central drive shaft 1U which is inserted through the bearing housing 5 and is provided with a drive 15. The side surfaces 12 and 13 of the rotor 6 run free from the inner wall of the housing 1, since both at 16 and 17 are provided with a breast. The disc 6 is rotatably mounted at the location of the breasts 16 and 17 in the housing 1 (in a manner not shown in the drawing) and this bearing is sealed for coal powder. The gaps 18 between the side surfaces 12 and 13 of the rotor and the housing are sealed against coal powder, which can enter it from space 3, by gas supplied via the supply openings 19.

The supply H of the housing is provided with a funnel-shaped connection 20 which can be connected by means of a flange 21 to a bunker with coal powder. In order to ensure a continuous supply of coal powder to the center 8 of the rotor, a transport screw 22 with drive 23 is arranged in the tubular feed.

The operation of the centrifugal pump shown in Figures 1 and 2 is as follows.

The coal powder is passed through the tube k via the funnel 20 under the influence of the rotating screw 22. An inert gas, such as cold recirculated product gas from the partial combustion of the coal powder, is also supplied with the powder from the space 30 (not shown) connected to the funnel 20.

The coal powder and the entrained gas thus end up via the passage 11 in the heart 8 of the rotor 6. In the rotating rotor 7901452 6, the coal particles and the entrained gas are moved from the heart 8 to the open ends 2k under the influence of the centrifugal force. from radial passages 10, where the coal particles leave the rotor at high speed. The tangential velocity of the carbon particles 5 "when they leave the rotor exceeds 20 m / sec. And is often of the order of 100 m / sec.

The space 25 between the rotor 6 and the housing 1 is formed such that from the highest point 26 in the direction of rotation 27 the radial distance 28 between the periphery 9 of the rotor 6 and the inside of the housing wall 29 gradually increases. , to the point (in this case it is the same point 26) where the space diverts tangentially away from the rotor, ie in Fig. 2 the line II where the diffuser 3 starts.

The passages 10 in the rotor 6 will each throw coal powder into space 25 in the substantially tangential direction at any point during the rotation of the rotor, and the initial flow of powder which moves from the point 26 in the direction 27 of the rotor 6 swells so gradually. The powder loses little speed on its way through space.

The moment the powder reaches the diffuser 3, it leaves the space 25 and, as can be seen from the drawing, the cross section of the diffuser there is substantially rectangular (see Fig. 1), while at the end of the diffuser (at the height of the flange 30) the cross section is larger and also circular. This transition and the flange 30 serve for the connection of the pump as a device for supplying coal powder. In the diffuser, the speed of the coal particles decreases and the pressure of the gas entrained with the particles increases.

Fig. 3 shows very diagrammatically a cross-section comparable to Fig. 2 of a double pump according to the invention.

The rotor 31 again consists of a disc which is rotatably mounted about an axis in a housing. The housing comprises, in addition to walls running parallel to the disk, two walls 32 and 33 which are complementary and each enclose the rotor 31 for 180 °. In this manner, the rotor 31 and the wall 32 enclose a space 3¼ which diverges in the direction of rotation 35 and which tide 36 changes into a diffuser 37 and the rotor 31 and the wall 33 enclose a space 38 which diverges in direction of rotation 35 and which it turns 39 into a diffuser 40. Seen along the circumference of the rotor, the space 34 starts where the space 38 ends and vice versa.

The rotor 31 includes a central coal powder feed 41 and two radial passages 42 and 43, the latter throwing powder (and gas) into space 34 and 38, respectively, in rotation.

It will be clear that, provided that the two housing halves are made identical, fluctuations in the flow of coal powder or, for example, deliberate variations in the rotational speed of the rotor will be noticeably identically noticeable at the outputs of the diffusers 37 and 40.

Finally, in Fig. 4, a single pump has been disassembled, the rotor 44 of which has four radial passages 45 and the housing 46 of which is provided with a number of gas supply nozzles 48 opening tangentially in the space 47 between the housing and the rotor.

The gas fed into space 47 via these nozzles 48 is accelerated there under the influence of the coal powder which is thrown into space 47 by rotor 44. The gas may be drawn through space 47 or injected into it at a desired initial velocity. By controlling the amount of gas and / or the velocity of the gas, influence can be exerted on the pressure and / or the velocity of the gas / powder mixture leaving the diffuser 49. On the other hand, the amount of gas and / or the speed of the gas can be adapted to the rotational speed of the rotor 44.

It will be clear that many variations are possible on the shape of the rotor, the shape and number of the radial passages therein (for example, the rotor may consist of two disks between which the radial passage consists of a total gap), as well as on the shape and cross section of the space between the rotor and the housing. The supply and drive of the drawn pump can of course also be effected in a different manner.

790 1 4 52

Claims (7)

Centrifugal pump for feeding powder in a high pressure space, comprising a feed and a rotor, the feed leading to the center of the rotor and the rotor having one or more substantially radial passages perpendicular to the axis of rotation which connect 5 on said feed and open at their outer end, characterized in that the rotor is surrounded by a housing whose radial distance from the rotor increases in the direction of rotation to a point where the housing leads tangentially away from the rotor. 2. A pump according to claim 1, characterized in that the housing is provided with one or more gas supplies opening tangentially in the space around the rotor. Pump according to claim 1 or 2, characterized in that some space is left between the housing and the sides of the rotor, into which gas supplies flow. 15 b. Pump according to claim 1, 2 or 3, characterized in that said housing consists of two identical halves, each enclosing half of the rotor and whose radial distance from the rotor increases in an equal manner to the point where the housing half is tangentially of the rotor leads away. Pump according to claim 1, 2, 3 or characterized in that the or each part of the housing which diverts tangentially away from the rotor is designed as a diffuser. 6. Method for partial combustion of powdered solid fuel at elevated pressure, characterized in that the powder is fed either directly or via an intermediate vessel to the partial combustion reactor via a centrifugal pump according to one or more of the preceding claims. 7- Device for the partial combustion of powdered solid fuel at elevated pressure, comprising a reactor into which one or more burners discharge, characterized in that the burner (s) is (are) connected to a pump either directly or via an intermediate vessel according to one or more of claims 1 to 5 * 7901452 Device according to claim 7S, wherein two burners are arranged diametrically opposite one another, characterized in that the burners are connected to a pump according to claim 4. 7901452