GB2061393A - Lock chamber and hydraulic conveying system - Google Patents

Abstract

A lock chamber device comprises a continuously rotatable rotor 12 having a plurality of lock chambers 1, 5, and a stationary housing 11 having pairs of openings A, A', C, C' for delivering and receiving the suspension, and a further pair of openings B, B'. Each of the chambers can be associated and aligned with each pair of openings by appropriate rotation of the rotor. A low-pressure circulating system 22, 21, 24, 18, 17 which contains relatively cold liquid is connected to the first pair of housing openings C, C'. A high-pressure circulating system 27, 28, 15, 26 which contains relatively hot liquid at a temperature above the boiling point of the liquid in the low-pressure circulating system is connected to the second pair of housing openings A, A'. A high-pressure circulating system 16, 34, 33 which includes cooling means 34 is connected to the third pair of housing openings B, B'. Each chamber reaches openings A, A' after the openings C, C' and the openings B, B' after the openings A, A' as the rotor is rotated, so that the hot liquid in the lock chambers is cooled before the chambers open to the low pressure system. <IMAGE>

Description

SPECIFICATION Lock chamber device This invention relates to a lock chamber device for transferring granular solids suspended in a liquid form a low-pressure zone to a high-pressure zone, the device being particularly useful when the pressures in said zones differ by at least 5 bars.

A lock chamber device has been proposed which comprises a continuously rotatable rotor having a plurality of lock chambers, which are separated from each other and serve to receive and deliver solids suspended in a liquid, a stationary housing having pairs of openings for receiving and delivering the suspension, and liquid-circulating systems for feeding the suspended solids into a lock chamber in a lowpressure zone and for discharging them from another lock chamber in a high-pressure zone, each liquid-circulating system comprising a pump.

Such lock chamber devices have been described in Opened German Specification No. 2,503,400 and in U.S. Patent Specifications Nos. 3,429,773 and 4,017,270. Problems will arise in the operation of these lock chamber devices when the temperature of the liquid, usually consisting of water, in the high-pressure circulating system exceeds the boiling point of the liquid under the pressure maintained in the low-pressure circulating system. Because each chamber is always at least partly filled with liquid, liquid will evaporate as it is transferred from the highpressure zone to the low-pressure zone so that the supply of solids with cold liquid into the lowpressure zone will be at least temporarily prevented. It is an object of the invention to reduce or eliminate these disadvantages.

According to the present invention there is provided a lock chamber device for transferring granular solids suspended in a liquid from a lowpressure zone to a high-pressure zone, comprising a continuously rotatable rotor having lock chambers the number of which is three or an integral multiple of three and which are separated from each other and serve to receive and deliver suspended solids, a stationary housing having three pairs of openings for receiving and delivering suspension, whereby each of the chambers can be associated and aligned with each pair of openings by appropriate rotation of the rotor, and liquidcirculating systems for feeding the suspended solids into a lock chamber in the low-pressure zone and for discharging them from another lockchamber in the high-pressure zone, each liquidcirculating system containing a pump and the liquid-circulating systems comprising a lowpressure circulating system containing relatively cold liquid and connected to the first pair of openings, a high-pressure circulating system containing relatively hot liquid at a temperature above the boiling point of the liquid in the lowpressure circulating system and connected to the second pair of openings, and a high-pressure circulating system containing relatively cold liquid and connected to the third pair of openings, the arrangement being such that each chamber reaches the second pair of openings after the first and the third pair of openings after the second as the rotor is rotated.

The present device is particularly useful for transferring carbonaceous solids, particularly fuels, such as coal or lignite, although the use of the lock chamber device is not restricted to such solids. The suspending liquid will often consists entirely or in part of water but this is also not essential.

The rotor has 3, 6 or 9 etc. lock chambers, i.e.

the number of lock chambers is an integral multiple of three. For reasons of manufacturing technology, a small number of chambers will be used. With only three lock chambers an entirely continuous operation of the liquid-circulating systems will not be possible because a chamber must not be included in two different pressure zones at the same time. These liquid-circulating systems can readily be operated continuously if the rotor has six chambers.

Each lock chamber extends transversely through the rotor and thus has two ports.

Theoretically, six chambers having 12 ports can be distributed in a rotor in such a manner that all ports have the same axial elevation although this would require that several chambers are strongly curved because none of the chambers must extend through or contact another. In order to facilitate the arrangement of the several chambers extending through the rotor, the ports of at least two or even three of the chambers have the same axial elevation on the surface of the rotor.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example some embodiments thereof, and in which: Figure 1 is a transverse sectional view of a lock chamber device and associated liquid-circulating systems, Figure 2 is a development of the upper surface of a lock rotor and the inside surface of a housing of the lock chamber device of Figure 1, Figure 3 is a view similar to Figure 2 showing another embodiment of a lock chamber device, and Figure 4 is a view similar to Figure 2 showing a third embodiment of a lock chamber device.

The lock chamber device shown in Figures 1 and 2 comprises a stationary housing 11 , which encloses a rotor 12. The housing 11 has three pairs of mutually opposite openings A, A', B, B', C, C'. The rotor 12 has six lock chambers, 1, 2, 3, 4, 5, 6, of which only chambers 1 and 5 are shown in Figure 1 for the sake of clarity. The chambers extend transversely through the rotor 12 and are staggered from each other and do not extend through or contact each other.

The left-hand half of Figure 2 shows a development of the cylindrically curved upper surface of the rotor 12, this upper surface having been broken for the showing of Figure 1 along the section line lI-Il in Figure 1, which is parallel to the axis and in Figure 2 constitutes the upper and lower boundaries.

The rotor 12 shown in Figures 1 and 2 has only lock chambers 1 to 6 which extend at right angles to the axis of rotation of the rotor. There are two ports 1 a and 1 b associated with chamber 1, two ports 2a and 2b associated with chamber 2, etc.

These ports 1 a, 2a,. . . 6a and 1 b,2b... 6b of the chambers are apparent from Figure 2 showing the upper surface of the rotor. The port 6a of chamber 6 has been bisected by the section line Il-Il and is seen at the top and bottom of Figure 2.

Figure 2 shows in its right-hand half a development of the cylindrical inside surface of the housing 11 of Figure 1, which has also been cut along line Il-Il. This inside surface of the housing 11 is formed with the above-mentioned openings A, B, C, A', B' and C', which are regularly spaced. In general, no packings are required between the openings because the clearance between the rotor and housing is minimized by precise machining so that any leakage will be negligible.

The length H of the openings A to C' is such that the rotation of the rotor 12 in the direction of the arrow P causes all the ports 1 a to 6a and 1 b to 6b of the several lock chambers to move past said openings in the housing. The width e of each opening of the housing is approximately as great as the sum of the with a of a chamber port and the width b of the land between adjacent ports; see the left hand half of Figure 1. Because e = a + b, that area of one or two chamber ports 1 a to 6b which is presented to a housing opening A to C' will always be as large as one port area.

When the lock chamber device is ready for operation, the housing 11 will cover the rotor 12 (see Figure 1). In Figure 2 these two parts are shown one beside the other for the sake of clarity.

In the le & -hand half of Figure 2, the covering of ports 1 a to 6b and the instantaneous association of the chambers and housing openings is indicated by the dotted-line showings of openings A and C.

The section line Il-Il in Figure 2 indicates the transverse sectional plane extending through the rotor and the housing as viewed in Figure 1 , the transverse sectional plane extending through the lock chamber 5.

When the rotor 12 is rotated in the direction of the arrow P during the operation of the lock chamber device, the chamber ports will move in that direction relative to the stationary housing.

The housing openings A, B and C communicate with inlet conduits 15, 1 6 and 17, see Figure 1, so that a flow can be established from the conduits and through the housing to those chambers which communicate with the openings at a given time.

The ports of such chambers are designated 1 a to 6a in the left-hand half of Figure 2. Those chamber ports through which the flow is from the chamber toward the housing are designated 1 b to 6b. The direction of flow in each chamber is changed after not more than one-half of a revolution of the rotor 12.

Solids, such as granular brown coal, which are suspended in water can be continuously transferred into a high-pressure reactor 20 by means of the lock chamber device shown in Figures 1 and 2.

The solids are fed through a conduit 19 to a reservoir 1 8. A supply of the suspension is continuously supplied from the reservoir 1 8 through the conduit 1 7 initialiy to the housing opening C. Under the suction applied by a circulating pump 21 through a conduit 22 to the opposite housing opening C', the residual liquid which is initially contained in the lock chamber communicating with C and C' (or in both such lock chambers) is removed and suspension to be supplied is caused to flow into the chamber (or the two chambers). The housing opening C' is provided with a sieve 23, which passes the liquid but retains the solids so that the chamber is filled with solids. The liquid sucked through the chamber is delivered by the pump 21 through a conduit 24 to the reservoir 18. Any surplus liquid can be withdrawn through a conduit 25.

That lock chamber which is being filled during the continuous rotation of the rotor 12, in Figures 1 and 2, i.e. the lock chamber 5 having ports 5a and 5b, is presented to the housing openings A and A', as the rotation of the rotor is continued.

The pair of openings, A, A' are included in a highpressure liquid-circulating system, in which a pump 26 forces hot liquid through the conduit 15 and housing opening A into the lock chamber (or the two lock chambers) communicating therewith and forces solids out of said chamber through opening A' into the conduit 27. The liquid in conduit 15 and that in conduit 27 are under a pressure which exceeds the pressure in conduits 17 and 22 by at least 5 bars. The temperature of the liquid in the conduits 15 and 27 exceeds the boiling point of the liquid under the pressure maintained in the conduits 1 7 and 22. The solids forced through the conduit 27 by the hot liquid are charged to the high-pressure reactor 20. The lock chambers moving away from the pair of openings A, A' are filled with hot liquid under high pressure.As the rotation of the rotor 12 is continued, these chambers reach the pair of openings B, B' and are filled with relatively cold liquid that is delivered by a circulating pump 33 through the conduit 1 6. The hot liquid which has been discharged is cooled in a cooler 34 to a desired lower temperature. The pressure in the conduit 1 6 is approximately the same as the pressure in the conduits 1 5 and 27 included in the high-pressure circulating system. On the other hand, the liquid entering from the conduit 1 6 through the housing opening B is at such a low temperature that virtually no steam or vapour is formed when the liquid is pressure-relieved to the pressure maintained in the conduits 1 7 and 22.

Where water is used as a carrier liquid, this means that the temperature downstream of the cooler 34 is generally below 1000C. because an approximately atmospheric pressure is usually maintained in the reservoir 1 8 and the associated conduits of the low-pressure circulating system.

The rotation of the rotor causes a chamber to move from the pair of openings B, B' to the pair of openings C, C', where said chamber is filled once more with suspended solids.

In the high-pressure circulating system, at least part of the liquid in the conduit 27 can be separated from the solids by a sieve, not shown, and can be recycled to the conduit 15 through a by-pass conduit 28 indicated by dotted lines. A suitable sieving device from which the separated solids can be delivered to the reactor 20 is described in U.S. Patent Specification No.

4,017270.

If granular brown coal fed into the reactor 20 is to be treated with steam in the reactor, the same is supplied with steam through a conduit 29. In such a case, temperatures of 250 to 3000 C. and a pressure in the range of 40 to 80 bars may be maintained in the reactor 20 and also in conduits 15 and 27 and the by-pass conduit 28 will then be superfluous. Treated brown coal is withdrawn through conduit 30 from the reactor, in which its water content has been greatly decreased. Drying of brown coal under high pressure in a steam atmosphere is known as the Fleissner process, in which surplus water leaves the reactor 20 through a conduit 31 and is recycled to the lock chamber device through conduit 1 5. Any loss of water is compensated from the conduit 32.

On the other hand, if granular coal is fed to a reactor for gasification under superatmospheric pressure, the quantity of water fed with the coal into the gasification zone should be minimized. In this case it is recommended to separate liquid in the conduit 27, as explained above, and to provide the by-pass conduit 28. The lock chamber device is not restricted to use in the Fleissner process or in connection with the gasification of granular coal under superatmospheric pressure but has a wide field of application.

As has been mentioned hereinbefore, the ports of all the lock chambers of a rotor may be arranged with the same axial elevation. The "axial elevation" is measured parallel to the section line Il-Il in Figure 2. In this rather theoretical case, the length H of the openings of the housing and the corresponding length of the chamber port could be equal; this would be desirable for some reasons. But some of the six chambers would then have to extend through the rotor in a highly curved configuration because they would otherwise extend through other chambers. The manufacture of such curved chambers is expensive.

A compromise between this arrangment and the requirement that the six lock chambers extending through the rotor should not be too strongly curved will be explained with reference to Figure 3. The left-hand half of Figure 3 shows the upper surface of a rotor 1 2a and the right-hand part of Figure 3 shows the inside surface of the associated housing 11 a. Like Figure 2, Figure 3 shows a development of cylindrical surfaces cut parallel to the axis.

There are no basic differences between the inside surface of the housing shown in Figure 3 and the inside surface of the housing shown in Figure 2; the rotor shown in Figure 3 also has six chambers. The ports of each pair of chambers have the same axial elevation. This applies in Figure 3 to the two chambers 41 and 44 which have the ports 41a, a,41 b and 44a, 446 and are not shown otherwise. The two chambers 42 and 45 having the ports 42a, 426 and 45a, 456 have also the same axial elevation and are offset from chambers 41 and 44. The last two chambers 43 and 46 having ports 43a. 436 and 46a, 46b have a third axial elevation.A comparison of Figures 2 and 3 shows that the rotor of Figure 3 has lock chambers arranged with a higher density so that its volume is utilized to a higher degree. As a result, the rotor may be smaller in overall height than that of Figure 2, or the chambers of the rotor shown in Figure 3 may be larger in cross-section.

The other explanations given in connection with the lock chamber device of Figures 1 and 2 apply also to the arrangement of Figure 3.

Figure 4 shows the cylindrical upper surface of a rotor 1 2b and the associated inside surface 11 b of the housing. The rotor has only three lock chambers 50, 51 and 52. Like Figures 2 and 3, Figure 4 shows a development of cylindrical surfaces cut parallel to the axis. The direction of rotation of the rotor is again indicated by the arrow P.

As the rotor of Figure 4 has only three chambers, which are indicated in Figure 4 by their ports 50a and 50b, 51a and 516 and 52a and 52b, all chamber ports may be arranged with the same axial elevation. For this reason the chamber ports 50a to 52b are vertically aligned in Figure 4.

The inside surface of the housing 1 11b is not basically different from the housings 11 and 11 a of Figures 1 to 3, and the conduits and pumps are also the same. Where three lock chambers are provided which have a total of six chamber ports, the number of chamber ports will equal the number of the housing openings A to C'. In order to avoid a simultaneous action of two different pressure zones on one chamber, the width of each land between adjacent housing openings must be at least as large as the width a of each port. As a result, the flow through a chamber will be interrupted when its ports are entirely covered by lands between housing openings.

Figure 4 illustrates a condition in which the lock chambers and housing openings are so associated with one another that all chamber ports are fully in register with respective openings. This will result in the most favourable conditions for the flow of liquid through the chambers and into the respective liquid-circulating systems. As the rotation of the rotor 1 2b is continued so that there is movement in the direction of the arrow P, the port area presented to the openings A to C' will decrease and will finally vanish. As the rotation of the rotor 1 2b is continued further, the port area presented to each housing opening will increase.

From these explanations it is apparent that this liquid can flow only intermittently through the chambers of the lock chamber device of Figure 4.

If a continuous flow of liquid in the chambers and the various liquid-circulating systems is to be maintained by simple means, the lock chamber devices described before, having at least six chambers, may be used.

The cross-sectional shapes of each chamber inside the rotor and at a port may be different.

Such changes in the cross-sectional shape of a chamber may afford advantages in manufacture particularly of the rotors of Figures 3 and 4 if the chambers are rather closely spaced. On the other hand, any change of the cross-sectional area of a chamber between its port and the interior of the rotor should be minimized so that there will be no constriction disturbing the flow of the suspension through the chamber.

Claims (5)

1. A lock chamber device for transferring granular solids suspended in a liquid from a lowpressure zone to a high-pressure zone, comprising a continuously rotatable rotor having lock chambers, the number of which is three or an integral multiple of three and which are separated from each other and serve to receive and deliver suspended solids, a stationary housing having three pairs of openings for receiving and delivering suspension, whereby each of the chambers can be associated and aligned with each pair of openings by appropriate rotation of the rotor, and liquidcirculating systems for feeding the suspended solids into a lock chamber in the low-pressure zone and for discharging them from another lockchamber in the high-pressure zone, each liquidcirculating system containing a pump, and the liquid-circulating systems comprising a lowpressure circulating system containing relatively cold liquid and connected to the first pair of openings, a high-pressure circulating system containing relatively hot liquid at a temperature above the boiling point of the liquid in the lowpressure circulating system and connected to the second pair of openings, and a high-pressure circulating system containing relatively cold liquid and connected to the third pair of openings, the arrangement being such that each chamber reaches the second pair of openings after the first and the third pair of openings after the second as the rotor is rotated.

2. A device as claimed in Claim 1, wherein the rotor has six chambers.

3. A device as claimed in Claim 2, wherein the ports of at least two of the chambers have the same axial elevation on the surface of the rotor.

4. A device as claimed in any one of Claims 1 to 4, wherein the pressures in said low-pressure zone and said high-pressure zone differ by at least 5 bars.

5. A lock chamber device substantialiy as hereinbefore described with reference to Figures 1 and 2, or Figure 3 or Figure 4 of the accompanying drawings.