EP1580511A2 - Device for maintaining temperature of bulk material - Google Patents

Abstract

An outer housing(5) contains a heat exchange section(2) comprising heat exchanger tubes(7) running downwards in the housing. Heat transfer fluid enters the housing at a feed point(8) and leaves via an outlet(9). An inlet for loose material exists at the upper end of the heat exchanger tubes and a material outlet at the lower end of the tubes. A buffer section(1) for loose material(20) is located prior to the upper end of the heat exchanger tubes(7). A material discharge section(3) lies below the lower end of the tubes. All tubes are held at their upper end in an inlet tube base(14) with feeding funnels(18) for each tube widening in the upward direction. The angle of entry(alpha ) of each funnel is 30-120[deg], preferably 40-100[deg]. Inside the housing(5) diverters produce a meandering fluid flow around the tubes. A compressed gas feed enters the discharge section(3) and feeds pulses of gas pressure. The heat exchange section(2) has a circular cross-section. Tubes have 2-12, preferably 3-8, equally spaced internal ribs running along the length. Ribs either connect with each other at the tube center axis or have free ends which stop short of the axis. A vibrator(21) may be located in the heat exchanger section(2) and partial vacuum can be applied to the plant. The relationship between the tube outer diameter(D) and spacing(a) of radially adjacent tubes is 1.10D=a=1.25D, preferably 1.15D=a=1.20D. The relationship between the internal diameter(d) of the tubes and the maximum particle diameter(c) is 15c=d, preferably 10c=d.

Description

Such tempering may be by heating or cooling of a bulk material. When there is a heat input to the bulk material, then - if this is still a carrier of moisture - at the same time a drying take place. The moisture is then supplied by means of a Gases discharged. Among bulk materials within the meaning of this invention are understood free-flowing bulk materials, such. Fertilizers, Plastic granules, plastic powder or food but also such. B. granulated sugar.

When heating and cooling of bulk solids is the heat transport from the bulk material to the heat transfer fluid or vice versa by the low limited thermal conductivity of the bulk material. For tempering such Bulk materials are used today shaft cooler, as for example in the form of a plate heat exchanger known from EP 0 444 338 B 1 are. The bulk material flows in between under the influence of gravity at least two mutually parallel heat exchanger plates through. In the heat exchanger plates are channels for a suitable cooling medium educated. The efficiency of such a plate heat exchanger is - based on the design effort - very bad. This also leads to a considerable height. Furthermore, the cleaning options in the area acted upon by the bulk material not favorable. Such a Plate heat exchanger requires that inlet manifold and outlet headers for the heat transfer fluid must be present.

The invention is therefore an object of the invention to provide a device for controlling the temperature of bulk material, which allows a high heat transfer and easy cleaning with a simple structure.
This object is achieved by the features of claim 1. The fact that the bulk material is passed through the heat exchanger tubes, precisely defined and easy-to-clean, smooth-walled spaces are given by which the bulk material moves. This leads to a simple cleaning possibility of the heat exchange section. The heat exchanger tubes have a large area, based on their cross-section, and high temperature gradients from the middle of the tube to the tube wall, so that a correspondingly intensive heat exchange can take place. As a heat transfer fluid suitable liquids, such as in particular water, but also gases or steam can be used. The design effort for the supply of the heat transfer fluid is low, since no inlet manifold or outlet collector for the heat transfer fluid is needed. Also, the cleaning on the side of the heat transfer fluid is easy to carry out. The bulk material is guided by gravity through the heat exchanger tubes. These are therefore usually arranged vertically, but can also be slightly inclined relative to the vertical, as long as it is ensured that the bulk material is passed by gravity through the heat exchanger tubes. So that the bulk material flows through the heat exchanger tubes without interference, the inner diameter of the heat exchanger tubes should be at least four to five times the particle size of the bulk material. As a result, a thorough emptying of the pipes is ensured. Instead of such a heat exchange section, a plurality of such sections may be provided in succession, so that in each case between two sections, a rearrangement of the bulk material takes place, whereby the temperature profile, which is adjusted from the pipe wall to the core of the bulk material, is made uniform. As a result, the temperature gradient is increased at the pipe wall in the subsequent heat exchange section and improves the temperature of the bulk material.

The heat exchange section, ie the actual tube bundle heat exchanger, can according to claim 2 in a simple manner a buffer section upstream of the bulk material and according to claim 3, a discharge section be subordinated. Through the development according to claim 4 is ensured in a particularly simple manner that the bulk material fed to the individual heat exchanger tubes by gravity is, without above the heat exchanger tubes dead spaces or dead areas remain in which bulk material remains, the heat exchange process is not subjected. Due to the special shape of the inlet tube bottom In addition, a complete residual emptying of the heat exchanger tubes achieved when emptying the heat exchange section. Furthermore, a bridging of the bulk material at the inlet into the Heat exchanger tubes avoided by the funnel shape. Advantageous areas the opening angle of the inlet funnel arise from claim 5th

The development according to claim 6 has the consequence that with particularly simple Means a particularly effective heat exchange in the cross-flow takes place, preferably in the cross-countercurrent.

Through the development according to claim 7 is achieved that a rearrangement of the bulk material takes place in the heat exchanger tubes and that in the Discharge section, in the tubes, in the inlet funnels as well as in the buffer section no bridging above the heat exchange section occurs. When the gas supply according to claim 8 in the form of Pressure surges done, the described effects are particularly effective. At the same time there is still a drying of the bulk material the compressed gas takes place, if necessary. Incidentally, the compressed gas also be tempered and in this respect for tempering the bulk material contribute.

The measures according to claim 9 lead to an improvement of the heat transfer on the side of the heat transfer fluid, so on the outside the heat exchanger tubes. This effect occurs especially at low Flow rates of the heat transfer fluid, since its Flow rate is increased.

By the measure according to claim 10 is a particularly compact and easy to manufacture construction of the device according to the invention achieved, in particular, also designed pressure-resistant for underpressure or overpressure can be.

Due to the configuration of claim 11, the heat transfer within the heat exchanger tubes improved. Claims 12 to 15 give this advantageous details again.

Due to the advantageous development according to claim 16 can be extremely poorly flowing bulk material, the flow conditions are improved.

Through the development according to claim 17 is possible, among others to achieve a particularly good drying of the bulk material under reduced pressure.

The embodiment according to claim 18 provides an advantageous alternative to Embodiment according to claim 4.

The claims 19 to 21 give measures again, by an optimal Arrangement of the heat exchanger tubes and in particular a particular thin design of the inlet tube bottom is achieved without the risk of a non-optimal bulk flow or even not optimal emptying of the buffer section would be given.

The statements in claim 22 ensure that on the one hand the bulk material without interference flows through the heat exchanger tubes, but on the other hand, a intensive contact with the heat exchanging surfaces of the Pipes is reached.

Fig. 1

eine Vorrichtung nach der Erfindung im vertikalen Längsschnitt in schematischer Darstellung,

Fig. 2

einen Querschnitt durch ein Wärmetauscher-Rohr,

Fig. 3

einen Querschnitt durch eine weitere Ausführungsform eines Wärmetauscher-Rohres,

Fig. 4

eine gegenüber Fig. 1 leicht abgewandelte Ausgestaltung der Vorrichtung,

Fig. 5

eine Draufsicht auf einen Einlauf-Rohrboden und

Fig. 6

den Einlauf-Rohrboden nach Fig. 5 in teilweise aufgebrochener Seitenansicht.

Further features, advantages and details of the invention will become apparent from the following description of an embodiment with reference to the drawing. It shows:

Fig. 1

a device according to the invention in vertical longitudinal section in a schematic representation,

Fig. 2

a cross section through a heat exchanger tube,

Fig. 3

a cross section through a further embodiment of a heat exchanger tube,

Fig. 4

a slightly modified embodiment of the device compared with FIG. 1,

Fig. 5

a plan view of an inlet tube bottom and

Fig. 6

the inlet tube plate according to Fig. 5 in a partially broken side view.

The device shown in Figure 1 for controlling the temperature of bulk material has an upper buffer section 1, a middle heat exchange section 2 and a lower discharge section 3. Sections 1, 2, 3 each have circular cross sections. The boxy, essentially enclosed buffer section 1 is with an upper inlet spigot 4 provided for supplying a bulk material to be tempered.

The heat exchange section 2 has a housing 5 in the interior thereof 6 parallel to each other heat exchanger tubes 7 each with distance are arranged from each other. The interior 6 is therefore a heat exchange space.

Adjacent to the discharge section 3 opens into the interior 6 of the housing 5 of the heat exchange section 2, a supply nozzle 8 for heat transfer fluid one. Adjacent to the buffer section 1 opens a discharge nozzle 9 from the interior 6 of the housing 5 from. In the interior 6 are deflecting plates 10 each transverse to the longitudinal direction of the tubes 7 in Distance from each other mounted such that a via the supply nozzle. 8 supplied heat transfer fluid according to the flow direction arrow 11 meandering through the interior 6 each transverse to the longitudinal direction the tubes gradually upward to the discharge nozzle 9 flows. The heat exchange section 2 is therefore for a cross-countercurrent designed the heat transfer fluid. The interior 6 can with a the Tubes 7 enveloping bed 12 of glass balls, steel balls and Plastic granules filled, which improve the heat transfer between the heat transfer fluid and the tubes 7 contributes. The filling this fill in the interior 6 via the discharge nozzle 9; a possible removal takes place via the supply nozzle 8. For securing the bed in the interior 6 are in the nozzle 8, 9 removable Retaining sieves 13 arranged. The size of the particles of the bed 12 should be such that after the preparation of the heat exchange section 2 can be incorporated in these. The particles of the bed In any case, 12 must be smaller than the pitch of the Tubes 7. The particles of the bed 12 preferably have spherical, lens or cylindrical shape.

The tubes 7 are at the top in a fixed to the housing 5 connected inlet tube bottom 14 and at the bottom connected to a spout tube plate 15, that they go to the buffer section 1 and to the discharge section 3 are open. Between the buffer section 1 and the heat exchange section 2 on the one hand and the heat exchange section 2 and the Discharge section 3 consist of flange 16 or 17. Like the Drawing is removed, the inlet tube plate 14 is designed so that each tube 7 a to the buffer section 1 towards expanding, for has respective narrowing tube 7 so narrowing inlet funnel 18, wherein adjacent funnels 18 are again dimensioned to be at the top meet in a relatively sharp edge 19. The inlet funnel 18 have an opening angle α, the at least 30 ° and a maximum of 120 ° is, but preferably in the range of 40 ° to 100 °. This will avoided that in the inlet tube plate 14 between adjacent tubes 7 dead spaces or dead surfaces arise on which bulk 20 lie remains, especially when emptying the heat exchange section 2 is not fed to a pipe 7 by gravity and therefore remains lying on the inlet tube plate 14.

On the outside of the housing 5 vibrators 21 are mounted by means of derer the entire heat exchange section 2 and thus the tubes 7 in Vibrations are added, creating a heat transfer on the inside the tubes 7, ie between these and the bulk material 20 improved becomes.

The discharge section 3 is in the form of a downwardly tapering cone-shaped funnel formed. Such a shape causes that Bulk 20 in the discharge section 3 at all points of any selected Cross section flows at almost the same speed, in this consideration, the immediate wall area is not taken into account is because there is always a delay due to wall friction. As a discharge device a rotary valve 22 is provided, the Housing 23 via a downpipe 24 connected to the discharge section 3 is. In the housing 23, a cellular wheel 25 is arranged, which is a motor 26 is rotary drivable. The motor 26 is from a level detector 27th controlled, in turn, the level of the bulk material 20 in the buffer section detected.

In the funnel-shaped discharge section 3 opens a feed line 28 for a gas. To this line 28 is a small pressure vessel 29th connected to the upstream in line 28 a shut-off 30 and a shut-off device 31 is arranged downstream. After opening the obturator 30 can with closed shut-off device 31 of the pressure vessel 29 with Compressed gas to be filled. With closed obturator 30 can by Opening the obturator 31 with appropriate emptying of the pressure vessel 29 a compressed gas stream in the funnel-shaped discharge section 3 are given. The compressed gas rises and causes a rearrangement of the bulk material in the heat exchanger tubes 7 and thus improving the heat transfer. At the same time this causes Gas a drying of the bulk material 20, if possible. Of course Both shut-off organs 30 and 31 can also be open to a continuous one Gas supply to allow. So that the gas supplied from the Device can also exit again is at the top of the buffer section 1 an exhaust pipe 36 is provided.

In the downpipe 24, a guide surface 33 is formed, which the bulk material 20 from the discharge section 3 to the revolving side of the in the direction of rotation 34th rotatably driven cellular wheel 25 passes. In other words, this means that directed over the guide surface 33 bulk material flow already in full Scope is directed to a cell 35 of the cellular wheel 25, when the Cell 35 during rotation in the direction of rotation 34 to the downpipe 24 out becomes. This is a uniform withdrawal of the bulk material 20 above the entire inlet cross section of the cellular wheel lock 22 ensured.

As Figure 2 can be removed, the heat exchanger tubes 7 in the longitudinal direction have continuous inner ribs 37, so that in each tube 7 itself again several channels 38 are formed, in the middle of the tube connected to each other. As shown in FIG. 3 can be removed, inner ribs 37 'also meet in the middle of the tube, so that a simple split Pipe 7 at two opposite inner ribs 37 'or a Stemrohr at three or more inner ribs 37 'is formed. The channels 38 'are completely separated from each other. Of course, the pipe 7 also inner ribs 37 ', which meet in the middle of the tube, and other inner ribs 37, which protrude only in the bulk material 20, have.

The number of inner ribs 37, 37 'is 2 to 12 and especially 3 to 8. The inner ribs 37, 37 'are at equal angular intervals on the circumference of the tube 7 distributed. The inner ribs 37 or 37 'can straight or twisted, d. H. helically.

Such tubes 7 with inner ribs 37, 37 'are usually made Aluminum and are produced by extrusion. Aluminum, but also Bundmetall, such. As copper, have compared to stainless steel Advantage of a 3 to 4 times higher thermal conductivity. By the Internal ribs 37, 37 'are also opposite the heat transfer surfaces a simple cylindrical tube 7 greatly enlarged while the Heat conduction routes for the supply or removal of heat from the pipe 7 in the bulk material 20 greatly shortened.

The embodiment according to FIG. 4 differs from that according to FIG. 1 in that that the device can be operated with negative pressure. The entire device is therefore connected to a suction fan 39, the the buffer section 1, the interior of the heat exchanger tubes 7 and applied to the discharge section 3 with partial vacuum. So this can be maintained, the supply of the bulk material 20 to the inlet nozzle 4 by means of a substantially vacuum-tight feeding device in the form of a cellular wheel lock 40. This lock 40 and the cellular wheel lock 22 close the entire device pressure-tight from. A gas supply and an exhaust pipe are naturally here unnecessary. In this embodiment, the inlet tube bottom 14 simplified, namely, trained; So he does not show the feed funnels 18 on. So that a complete emptying is still possible, If one or more air supply nozzles 41 are arranged in the buffer section 1, through the air for emptying or cleaning the Inlet tube bottom 14 'can be injected. There are also washing nozzles 42 provided in the buffer section 1, through which a washing liquid, usually so water, can be supplied to the buffer section 1, the heat exchanger tubes 7 and the discharge section 3 from adhering dusts to clean. Incidentally, the comments are correct according to FIGS. 1 and 4 match.

As can be seen from FIGS. 5 and 6, one in FIG. 1 is only more schematic illustrated tube bottom 14 circular inlet openings 43 for the tubes 7, which indicated on dash-dotted lines pitch circles 44, 45, 46th are arranged around the central longitudinal axis 47 of the housing 5. The inlet tube bottom 14 is thus circular in shape; accordingly that is Housing 5 circular cylindrical. As clearly shown in Fig. 5, has this arrangement of the inlet openings 43 on pitch circles 44, 45, 46 has the advantage that the inlet funnel 18 - even in the area of the outer Edge 48 of the tube sheet 14 - areas of a greater distance to have this edge 48 or to an adjacent inlet funnel. This has the consequence of being in compliance with the above range for the opening angle α of the tube sheet 14 is relatively thin can be trained.

The diameter of the inlet openings essentially corresponds to the Outer diameter d of the tubes 7. For the pitch a radially adjacent Openings 41 and thus tubes 7 are 1.1 D ≤ a ≤ 1.25 D and preferably 1.15 D ≤ a ≤ 1.20 D. The same applies to the pitch b in tangential direction between adjacent openings 43 and thus tubes 7: 1.10 D ≤ b ≤ 1.25 D and preferably 1.15 D ≤ b < 1,20 D.

For the inner diameter d of the tubes 7 applies in comparison to the maximum Particle diameter c of the bulk material 20, i. to the maximum grain size c of the bulk material 20: double distance 15 c ≤ d and preferably 10 c ≤ d.

Claims (22)

Device for controlling the temperature of bulk material (20) with a heat exchange section (2) having a housing (5), with heat exchanger tubes (7) arranged in the housing (5) in the direction of gravity, with a feed (8) for a heat transfer fluid opening into the housing (5), with a discharge (9) for the heat transfer fluid leaving the housing (5), with a at the upper end of the tubes (7) arranged bulk material inlet for supplying the bulk material (20) into the tubes (7) and with an outlet for the bulk material (20) provided at the lower end of the tubes (7). Apparatus according to claim 1, characterized in that the upper end of the heat exchanger tubes (7) is preceded by a buffer portion (1) for the bulk material (20). Apparatus according to claim 1 or 2, characterized in that the lower end of the heat exchanger tubes (7) is arranged downstream of a discharge section (3) for the bulk material (20). Device according to one of claims 1 to 3, characterized in that the heat exchanger tubes (7) are held at its upper end in an inlet tube bottom (14), in the individual tubes (7) opening, upwardly expanding inlet Funnel (18). Apparatus according to claim 4, characterized in that the inlet funnels (18) have an opening angle (α), for which applies: 30 ° ≤ α ≤ 120 ° and preferably 40 ° ≤ α ≤ 100 °. Device according to one of claims 1 to 5, characterized in that in the housing (5) of the heat exchange section (2) deflecting means are provided which guide the heat transfer fluid meandering on the heat exchanger tubes (7) along. Apparatus according to claim 3, characterized in that in the discharge section (3) opens at least one pressurized gas supply. Apparatus according to claim 7, characterized in that the at least one compressed gas supply is designed to supply gas pressure surges. Device according to one of claims 1 to 8, characterized in that in the housing (5) of the heat exchange section (2) a heat exchanger tubes (7) enveloping bed (12) is provided. Device according to one of claims 1 to 9, characterized in that at least the heat exchange section (2) has a circular cross-section. Device according to one of claims 1 to 10, characterized in that the heat exchanger tubes (7) are provided with extending in their longitudinal direction inside ribs (37, 37 '). Apparatus according to claim 11, characterized in that the inner ribs (37) project freely towards the middle of the pipe. Apparatus according to claim 11, characterized in that the inner ribs (37 ') are interconnected in the middle of the tube. Device according to one of claims 11 to 13, characterized in that 2 to 12 and preferably 3 to 8 inner ribs (37, 37 ') are provided. Device according to one of claims 11 to 14, characterized in that the inner ribs (37, 37 ') are distributed uniformly on the circumference of the tube (7). Device according to one of claims 1 to 15, characterized in that the heat exchange section (2) at least one vibrator (21) is arranged. Device according to one of claims 1 to 6 and 9 to 16, characterized in that it can be acted upon by partial vacuum. Device according to one of claims 2, 3 and 6 to 17, characterized in that the heat exchanger tubes (7) at its upper end to an inlet tube bottom (14 ') are held, which is formed substantially planar, and
that above the inlet tube bottom (14 ') in the buffer section (1) at least one air nozzle (41) for blowing out the inlet tube bottom (14') of bulk material (20) is provided. Apparatus according to claim 4, characterized in that in the inlet tube bottom (14) inlet openings (43) for the heat exchanger tubes (7) are formed on part circles (44, 45, 46) about a central longitudinal axis (47) of the housing (5) are arranged. Apparatus according to claim 19, characterized in that for the ratio of outer diameter (D) of the heat exchanger tubes (7) and pitch (a) radially adjacent tubes (7) applies: 1.10 D ≤ a ≤ 1.25 D and preferred 1.15 D ≤ a ≤ 1.20 D. Apparatus according to claim 19, characterized in that for the ratio of outer diameter (D) of the heat exchanger tubes (7) and pitch (b) of tangentially adjacent tubes (7) applies: 1.10 D ≤ b ≤ 1.25 D and preferably 1.15 D ≤ b ≤ 1.20 D. Apparatus according to claim 1, characterized in that for the inner diameter (d) of the heat exchanger tubes (7) in relation to the maximum diameter (c) of particles of the bulk material (20) applies: 15 c ≤ d and preferably 10 c ≤ d.

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