JPH0341209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-stage spouted bed type calcination apparatus used for calcination of powdery raw materials such as cement or alumina.

The following is an overview of the case where powdered fluid raw materials are used as cement raw materials. In modern cement firing equipment, a calcination device with an independent fuel supply means is installed between the preheating device and the calcination furnace. After being preheated in a floating state in a preheating device using exhaust gas from The calcined raw material is similarly supplied to a calcining device equipped with an independent fuel supply means, where the remaining calcining reaction and clinker production reaction are carried out.

In such a calcination device, the calcination process is composed of multiple stages of calcination zones each equipped with a fuel supply means, and the raw material powder is sequentially passed through these multiple stages of calcination zones to perform calcination. There is something to be done, but
In the calcination device, the calcination reaction is performed at a relatively low temperature,
The calcination reaction can be promoted more effectively without coating the walls of the calcination equipment with raw material powder or clogging the powder separator, further increasing the productivity of the calcination equipment. It has the ability to be enhanced.

FIG. 1 is a diagrammatic system diagram illustrating such a cement raw material firing apparatus, in which the flow of hot gas is shown by solid line arrows, and the flow of raw material powder is shown by broken line arrows.

The apparatus consists of a preheating device 1 for preheating the raw material powder, a calcination device 2 for the calcination process, a firing furnace 3 such as a rotary kiln, and a clinker cooling device 4 for cooling the fired product.

The preheating device 1 is a powder separator C ₁ such as a cyclone.
~ C ₃ and a duct 6, etc., and the calcination device 2 is a multi-stage type arranged in series, and has a calcination zone 21 on the downstream side and a calcination zone 22 on the upstream side when viewed in the flow direction of hot gas. Multi-stage calcining zone (two stages in the case of Figure 1)
are arranged in series, and each calcining zone 2
Reference numerals 1 and 22 are composed of calciners 7 and 8 each equipped with fuel supply devices 7a and 8a, and powder separators _C4 and _C5 attached to the calciners.

The raw material powder supplied from the raw material input chute 5 is sent to each powder separator C ₁ to _{C 3} that constitute the preheating device 1.
On the other hand, the high-temperature exhaust gas from the calcination furnace 3 and the calcination device 2 is sucked by the induced draft fan 13 and rises inside the preheating device 1, so that it flows inside the duct 6 and inside the powder separators _C1 to _C3. Heat exchange and separation between the raw material powder and the high-temperature gas is repeated at the step. The preheated raw material powder is introduced from the lowermost powder separator C ₃ of the preheating device 1 to the downstream primary calcination furnace 7 that constitutes the calcination device 2, and then passes through the powder separator C ₄ and the raw material chute 11. It is introduced into the secondary calcining furnace 8 on the upstream side.

On the other hand, since the combustion exhaust gas still containing sufficient oxygen from the secondary calciner 8 is connected to be discharged to the primary calciner ₇ via the powder separator C5,
High-temperature combustion air introduced from the cooling device 4 to the secondary calciner 8 through the high-temperature air conduit 10 and fuel supplied from fuel supply devices 7a and 8a provided in each calciner 7 and 8, respectively. Therefore, combustion occurs in the calcining furnaces 7 and 8, and by receiving the combustion heat and the heat of the exhaust gas from the calcining furnace 3, the raw material powder is
It is calcined while passing through the secondary calcining zone 21 and the secondary calcining zone 22.

The calcined raw material powder enters the firing furnace 3 from the powder separator C ₅ through the raw material chute 12 and the firing furnace inlet cover 9, and is supplied to the primary combustion chamber from the fuel supply device 3a installed at the outlet end cover 19 of the firing furnace 3. The clinker undergoes necessary heat treatment in the kiln 3 due to the combustion heat of the fuel supplied together with the air, and is then cooled in the cooling device 4.

Note that air for clinker cooling is supplied by a forced air blower 16, and a portion of the high-temperature air heated by exchanging heat with the clinker is distributed and introduced into the secondary calcining zone 22 and the firing furnace 3. Excess air is exhausted by the induced draft fan 17. The clinker discharged from the cooling device 4 is then carried out to the next process by a conveyor 18.

According to the calcination device for cement raw material powder as shown in FIG. It does not flow into the calcining zone 22, and the downstream calcining zone 2 does not flow into the calcining zone 22 on the upstream side.
1, the partial pressure of carbon dioxide gas in the hot gas can be reduced in the upstream calcining zone 22, and the residence time of the raw material powder in the calcining device 2 as a whole becomes longer. Therefore, the calcination reaction of the raw material powder in the calcination device 2 can be efficiently promoted at a relatively low temperature.

FIG. 2 shows an example of the configuration of the upstream calcining zone 22 in such a cement raw material calcining apparatus. As shown in the figure, a secondary calcination furnace 8 forming a calcination zone 22
A combustion chamber 36 equipped with a lower fuel supply device 8a and an upper mixing chamber 37, each of which is formed as a spouted bed vessel with a lower part in the shape of an inverted truncated cone, are connected in the vertical direction with an intermediate neck 35 as a boundary. Composed of stacked
The secondary calcination furnace 8 as a whole is erected above the inlet end cover 9 of the firing furnace 3 via an inlet duct 38 for the exhaust gas of the firing furnace 3 . Further, a separation cyclone C ₅ is connected to the side wall 39 of the mixing chamber 37 above the calciner 8 via an exhaust gas duct 40 , and a raw material discharge chute 12 of the separation cyclone C ₅ is connected to the inlet end cover 9 . has been done.

In the secondary calcination furnace 8, the raw material powder charged from the raw material input chute 11 is combined with combustion heat due to combustion of air sent from the high temperature air conduit 10 and fuel supplied from the fuel supply device 8a, and 3
The calcined raw material powder is separated from the exhaust gas by the separation cyclone C5, and the raw material powder is separated from the exhaust gas by the separation cyclone _C5 . It is configured to be introduced into the inlet end cover 9 of the firing furnace 3 through a discharge chute 12 .

However, the separation cyclone _C5 , which separates raw materials by centrifugal force accompanying the swirling of the internal airflow, is installed on the side of the calciner 8 (horizontal center-to-center distance L), and the fluidity of the calcined raw material has decreased due to the high temperature, so the inclination angle θ of the raw material discharge chute 12 of the separation cyclone _C5 cannot be made very small (55 to 60 The height of the calciner 8 is determined by the heightwise position of the separation cyclone _C5 . Therefore, in the calcining zone 22, although the amount of fuel used is less than that in the calcining zone 21, about 1/3 or less, the height of the calcining furnace 8 cannot be made small, and each stage cannot be separated. Since a cyclone is attached, there are drawbacks such as the equipment becomes large-sized and the pressure loss as the calcining device 2 is large.

The present invention aims to solve the above-mentioned drawbacks and provide a multi-stage spouted bed type calcination device that is small in size and consumes little power. , spouted bed containers each having an inverted truncated cone shape at the bottom are stacked in multiple stages, communicating vertically through a small-diameter neck, and exhaust gas from the firing furnace is introduced into the bottom end of the lowest spouted bed container. In a multi-stage spouted bed type calciner in which the spouted bed container in the uppermost stage is connected to a separation cyclone through an exhaust gas duct, a fuel supply device is connected to the spouted bed container in each stage, and a fuel supply device is connected to the spouted bed container in the uppermost stage. A raw material input port is provided in the spouted bed container, and a raw material discharge port of the separation cyclone is connected to the second spouted bed container from the top,
A raw material collection hopper is attached to the inverted truncated conical wall of the spouted bed vessel from the second stage onwards, and the raw material discharge port of the hopper is connected to the inlet end cover of the spouted bed vessel or firing furnace in the lower stage. The present invention provides a multi-stage spouted bed type calcination device for fluid powder, which is a connected point.

Next, embodiments embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention. Incidentally, the same reference numerals are used to describe the same elements as those used in the conventional example shown in FIGS. 1 and 2. Here, FIGS. 3 to 5 show schematic side views of multistage spouted bed type calcination apparatuses according to first to third embodiments of the present invention.

First, a first embodiment of the present invention shown in FIG. 3 will be described.

As shown in the figure, there is a tapered part 42 above the inlet end cover 9 of the firing furnace 3, the lower part of which is in the shape of an inverted truncated cone.
Spouted bed vessel 36' constituting the second stage calcining zone 22
is erected through an inlet duct 38 for the firing furnace exhaust gas. A hopper 43 for collecting raw material is provided in the tapered portion 42 of the spouted bed container 36', and a raw material discharge port of the hopper 43 is connected to the inlet end cover 9 through a raw material chute 45 equipped with a gate valve 44. connected,
The structure is such that the raw material collected by the hopper 43 is introduced into the inlet end cover 9. Also, near the lower end of the body 46 of the spouted bed container 36', there is a fuel supply device 3 as usual.
6a' is connected to a high temperature air conduit 10 for introducing high temperature air from the cooling device 4 (FIG. 1).

The upper part of the spouted bed vessel 36' has a tapered part 47 whose lower part is shaped like an inverted truncated cone, and the spouted bed vessel 48 constituting the first stage calcining zone 21 is connected to the spouted bed vessel 36' through the small diameter intermediate neck part 35. It is erected. The tapered part 47 of the spouted bed container 48 is provided with a fuel supply device 48a, the body part 49 of the spouted bed container 48 is provided with a raw material chute 50 which is a raw material input port, and the upper part of the spouted bed container 48 is provided with a raw material chute 50 which is a raw material input port. A cyclone 53 separates the calcined raw material and exhaust gas through the upper tapered part 51.
An exhaust gas duct 52 leading to is connected. In addition, the raw material outlet 54 of the separation cyclone 53
is connected to the body 46 of the second spouted bed vessel 36' from the top via a raw material chute 55 equipped with a gate valve 67.

Next, to explain the operation of the above embodiment, when the raw material preheated by the preheating device 1 (FIG. 1) is charged from the raw material chute 50 to the spouted bed container 48 constituting the first stage calcining zone. , in the spouted bed vessel 48, fuel supplied from a fuel supply device 48a;
Since a combustion reaction is occurring with the exhaust gas that still contains sufficient oxygen from the lower spouted bed vessel 36', the input raw material receives the combustion heat from the combustion reaction and the heat possessed by the exhaust gas, and is heated to 1. Next, it is calcined.

The raw material that has been primarily calcined in this way is stored in a spouted bed vessel 48.
It is blown up by the gas flow rising therein, and is led to the separation cyclone 53 through the exhaust gas duct 52. The raw material separated from the exhaust gas here is fed through the raw material chute 55 into the spouted bed container 36' constituting the second stage calcining zone 22, and the combustion heat of the fuel supplied from the fuel supply device 36a' and the exhaust gas The uncalcined raw materials are also calcined by the heat possessed by the .
A part of the raw material is blown up by the gas flow rising inside the spouted bed vessel 36' and circulated to the spouted bed vessel 48, while the other part descends along the inner wall of the body 46 as shown by arrow a. The torso 46 is caught in the vortex
When it reaches the tapered part 42, it is collected in a raw material collection hopper 43, and then supplied to the firing furnace 3 through the inlet end cover 9 by the raw material chute 45, where it is fired.

Therefore, in this example, it is possible to construct two stages of calcination zones within approximately the same height as the one-stage calcination zone according to the conventional example shown in Fig. 2, and the calcination efficiency is This makes it possible to significantly reduce the overall height of the device. Furthermore, compared to the conventional two-stage calciner shown in FIG. 1, the second-stage separation cyclone can be omitted, so the pressure loss in the calciner 2 can be significantly reduced.

Next, a multi-stage spouted bed type calcination apparatus according to a second embodiment of the present invention will be described in which the spouted bed container 48 constituting the first stage calcination zone 21 is divided into a combustion chamber 56 and a mixing chamber 57.

As shown in FIG. 4, a spouted bed vessel 36'' constituting the second stage calcining zone 22 is erected above the inlet end cover 9 via an introduction duct 38.
The lower and upper tapered portions 42' and 58 of 6'' have eccentric openings, and the raw material is captured on the tapered surface 42'' on the opposite side to the eccentric direction of the opening of the eccentric lower tapered portion 42'. A collection hopper 43' is connected.

The upper part of the spouted bed container 36'' has a lower tapered part 47' and an upper tapered part 59 which are eccentric in the opposite direction to the spouted bed container 36'' through the intermediate neck part 35 where the fuel supply device 56a is provided. A mixing chamber 57 is provided in the upper part of the combustion chamber 56 and has a lower tapered part 61 that is eccentric in the opposite direction to the combustion chamber 56 through an intermediate neck part 60. is installed.

The axes of the intermediate necks 35 and 60 connecting the spouted bed vessel 36'', the combustion chamber 56, and the mixing chamber 57 are provided on the vertical line m passing through the center of the inlet end cover 9 of the firing furnace 3, and With reference to the line (hereinafter referred to as the center line m), the bodies of the spouted bed vessel 36'', the combustion chamber 56, and the mixing chamber 57 are sequentially moved from left to right to
It is mounted eccentrically to the left. This is caused by the gas flow blown up from the bottom to the top of each spouted layer vessel 3.
6'', 56, and 57 along the wall surfaces indicated by arrows a to promote mixing of the raw material and hot gas and to extend the residence time of the raw material in each calcining zone 21 and 22. This is to promote the sintering reaction.

By the way, the raw material chute 50 is provided in the body part 46 which is farther from the center line m of the combustion chamber 56, and the tapered part 61 of the mixing chamber 57 is provided in the body part 46' which is closer to the center line m of the combustion chamber 56. A raw material chute 64 is connected to which the raw material collected by the raw material collection hopper 62 provided in the hopper is guided. Further, a diagonally downward straight duct 66 is connected to the body portion 65 of the mixing chamber 57 closer to the center line m, and guides the raw material to the separation cyclone 53. Further, the raw material discharge port 54 of the separation cyclone 53 is connected to the second spouted bed vessel 36'' from the top via a raw material chute 55.

In the calcination device according to the above embodiment, the raw material fed into the combustion chamber 56 from the raw material chute 50 gradually receives the combustion heat of the fuel from the fuel supply device 56a and the heat possessed by the exhaust gas from the spouted bed vessel 36''. It is calcined and passed through a mixing chamber 57 to a separation cyclone 5.
Guided by 3. On the other hand, the body 6 that is caught in the vortex (arrow a) in the mixing chamber 57 and is far from the center line m
The raw material descending along the side wall of 5' is collected by a hopper 62 and returned to the combustion chamber 56, where it is calcined again. Such circulation extends the residence time of the raw material within the spouted bed vessel 48' and promotes the calcination reaction.

The raw material collected by the separation cyclone 53 is led to the spouted bed vessel 36'' via the raw material chute 55, where the combustion heat of the fuel from the fuel supply device 36a'' and the retained heat of the exhaust gas are transferred again to the secondary temporary. Burned.

The raw material that has been sufficiently calcined in this manner is collected by the raw material collection hopper 43' and introduced into the inlet end cover 9 of the firing furnace 3.

By using the eccentric spouted bed vessels 36'' and 48' as in the above embodiment, the generation of a vortex (arrow a) near the body part farther from the center line m is promoted;
In addition, by employing a diagonally downward straight duct 66 extending from the body of the mixing chamber 57 to the separation cyclone 53, mixing of the gas and the raw material in the upper part of the mixing chamber 57 is promoted, and furthermore, the preheating device 1 (the 1) can be placed in a low position. It is also possible to directly connect the raw material chute 64 to the spouted bed vessel 36'' that constitutes the second stage calcination zone 22, as shown by the two-dot chain line in FIG. Since the combustion chamber is divided into a chamber 56 and a mixing chamber 57, combustion is completed within the mixing chamber 57, and there is no problem such as unburned gas flowing into the preheating device 1 (FIG. 1).

Next, a multi-stage spouted bed calcining apparatus according to a third embodiment of the present invention will be described. As shown in FIG. 5, the first, second and third calcining zones 31, 3
2 and 33, respectively, and the fuel supply devices 70a,
Combustion chambers 70, 69 and 68 formed as spouted bed vessels having 69a and 68a are stacked in three stages with their inlets and outlets communicating. The lowest stage (third stage) combustion chamber 68 is located at the inlet end cover 9 of the firing furnace 3.
However, the combustion chambers 70 and 69 of the first and second stages are arranged eccentrically with respect to the center line m passing through the centers of their inlets and outlets. ing. Further, the third and second stage combustion chambers 68 and 69 are connected to high temperature air conduits 10 and 10a that introduce high temperature air from the cooling device 4, and the first stage combustion chamber 70 is connected to the exhaust gas pipes 10 and 10a. A separation cyclone 53 for separating the raw material and the raw material is connected via an exhaust gas duct 66, and a raw material outlet 54 of the separation cyclone 53 is connected to a second stage combustion chamber 69 via a raw material chute 55. Hoppers 72 and 43 for collecting raw materials are provided in the inverted truncated conical taper portions 71 and 42 at the bottom of the second and third combustion chambers 69 and 68, and the raw material discharge ports 73 and 44 are respectively provided. Raw material chute 74 and 4
5 to the lower combustion chamber 68 and the inlet end cover 9.

According to the calcination device having such a configuration, the calcination zones 31, 32, and 33 consisting of three stages can be arranged compactly, and the raw material passes through the calcination zones in which the carbon dioxide concentration is sequentially reduced. It is highly calcined and finally discharged to the kiln. Further, at this time, since the second and third stage calcining zones 32 and 33 do not require separation cyclones, the pressure loss in the calcining apparatus can be reduced. Incidentally, instead of making the centers of the bodies of the spouted bed vessels of each stage eccentric to each other in sequence, the bodies are arranged concentrically, and the introduction duct 38 and the intermediate neck 7 at the lower end are arranged concentrically.
A similar effect can be obtained by arranging hoppers 5 and 76 sequentially eccentrically with respect to a vertical line passing through the center of the kiln. It is also possible to provide it across sections. Furthermore, according to the arrangement shown in FIG. 5, since the high temperature air conduit 10a is also connected to the second stage combustion chamber 69, the amount of gas passing through the lowest stage combustion chamber 68 can be reduced. can be made even smaller. Note that the lowest-stage high-temperature air conduit 10 is omitted, high-temperature air is introduced into the lowest-stage combustion chamber 68 through the firing furnace 3, and high-temperature air is introduced from the cooling device 4 (FIG. 1) only through the high-temperature air conduit 10a. It is also possible to guide the air to the second stage combustion chamber 69, and by doing so, the arrangement of the high temperature air conduit 10a can also be simplified.

As described above, the present invention stacks a plurality of spouted bed containers, each of which has an inverted truncated conical lower part, vertically connected to each other through a small-diameter neck above the inlet end cover of a firing furnace. , in a multi-stage spouted bed type calcination device in which an inlet for exhaust gas from the firing furnace is opened at the lower end of the bottom powder bed container, and the top spouted bed container is connected to a separation cyclone via an exhaust gas duct,
A fuel supply device is provided in each of the spouted bed containers in each stage, and a raw material input port is provided in the spouted bed container in the uppermost stage,
The raw material outlet of the separation cyclone is connected to the spouted bed container in the second stage from the top, and a hopper for collecting the raw material is attached to the inverted truncated conical wall of the spouted bed container in the second stage from the top. Since this is a multi-stage spouted bed type calcination device characterized in that the raw material discharge port of the hopper is connected to the spouted bed container or the inlet end cover of the firing furnace located below the hopper, it is possible to configure the calcination device into multiple stages. The overall height is smaller, the separation cyclone in the lower stage is omitted, and the length of the raw material chute is shortened, which significantly reduces equipment costs and reduces pressure loss in the calcination equipment. Therefore, driving power can be saved.

[Brief explanation of drawings]

FIG. 1 is a diagrammatic system diagram of a conventional cement raw material firing device, FIG. 2 is a side view of the upstream calcining zone of the same device, and FIGS. FIG. 3 is a schematic side view of a multi-stage spouted bed calcination device according to Example 3; (Explanation of symbols), 2... Calcination device, 21, 22,
31, 32, 33... Calcination zone, 3... Firing furnace, 9
...Inlet end cover, 10,10a...High temperature air conduit,
36', 36'', 48, 48', 68, 69, 70
...Spouted bed type container, 35, 60, 75, 76...
Cervical, 36a', 36a'', 48a, 56a, 68
a, 69a, 70a... fuel supply device, 43, 4
3', 62, 72... hopper for collecting raw material, 52,
66...Exhaust gas duct, 53...Separation cyclone, 56...Combustion chamber, 57...Mixing chamber.

Claims (1)

[Scope of Claims] 1. A plurality of spouted bed vessels each having an inverted truncated conical lower part are stacked above the inlet end cover of a firing furnace and communicated in the vertical direction through a small-diameter neck, In a multi-stage spouted bed type calcination device, an inlet for exhaust gas from the calcination furnace is opened at the lower end of the lowest spouted bed container, and the uppermost spouted bed container is connected to a separation cyclone via an exhaust gas duct. A fuel supply device is provided in each of the spouted bed containers, a raw material input port is provided in the spouted bed container in the uppermost stage, and a raw material outlet of the separation cyclone is connected to the spouted bed container in the second stage from the top. A raw material collection hopper is attached to the inverted truncated conical wall of the spouted bed vessel in the second and subsequent stages, and the raw material discharge port of the hopper is connected to the lower spouted bed vessel or the inlet end cover of the firing furnace. This is a multi-stage spouted bed calcining device. 2. The multi-stage spouted bed calciner as set forth in claim 1, wherein a combustion air introduction duct is connected to the vicinity of the lower end of the side wall or to the inverted truncated conical wall surface of at least the lowermost spouted bed vessel. 3. Claim 1, in which a combustion air introduction duct is connected to the vicinity of the lower end of the side wall or to the inverted truncated conical wall surface of at least the second spouted bed vessel from the bottom.
The multi-stage spouted bed type calcination equipment described in . 4. The multi-stage spouted bed type tentative structure according to any one of claims 1 to 3, wherein the uppermost spouted bed container is composed of a lower combustion chamber and an upper mixing chamber with an intermediate neck as a boundary. Baking equipment.