JPH0431520Y2 - - Google Patents

Description

[Detailed explanation of the invention] "Industrial application field" This invention relates to a multistage heat exchange device, in particular, for example, preheating cement raw materials, granular limestone, etc. with hot gas, or preheating calcined alumina, etc. with air. This invention relates to a multi-stage heat exchange device between gas and powder for cooling.

[Prior Art] First, a prior art multi-stage heat exchanger for powdered granular material will be briefly described using powdered granular material as a cement raw material as an example.

An example of an overall system diagram of a conventional cement raw material firing facility is shown in FIG. In the figure, the flow of raw material powder is shown by broken line arrows, and the flow of hot gas is shown by solid line arrows.

This device mainly includes a heat exchange device 1 consisting of vertically arranged cyclones C ₁ to C ₃ for preheating raw material powder, a calcining furnace 2 attached with a separation cyclone C ₄ ,
It is comprised of a firing furnace 3 such as a rotary kiln for firing clinker, and a clinker cooling device 4.

In such a cement raw material firing apparatus, the raw material powder introduced from the powder input chute 5 sequentially descends through the preheating cyclones C ₁ to C ₃ of the heat exchange device 1 . During that time, the raw material powder is sucked by the exhaust gas induction fan 8 and gradually preheated by hot gas rising through each exhaust gas duct 7 (hereinafter referred to as a gas duct), and then supplied to the calcining furnace 2. be done.

In the calcining furnace 2, high-temperature exhaust gas sent from the clinker cooling device 4 is introduced through the bleed duct 13, and calcining fuel is supplied from the burner 6. Therefore, the raw material powder that has been preheated and supplied to the calcining furnace 2 is calcined by the combustion heat generated by the hot air and the burner 6.

The calcined raw material powder enters the lowermost separation cyclone _C4 together with hot air, and then is introduced into the firing furnace 3 via the raw material chute 15 and the connection housing 12.

The high-temperature exhaust gas sent from the clinker cooling device 4 and the firing fuel from the burner 9 are introduced into the firing furnace 3, and the clinker that has been fired at high temperature is discharged to the clinker cooling device 4. Ru.

On the other hand, hot air consisting of high-temperature exhaust gas is separated in separation cyclone C ₄ and ascends through duct 7 toward cyclone C ₃ .

Cyclones C ₁ to C ₃ for preheating raw material powder and granular materials used in this type of heat exchanger device are shown in Fig. 6 (partially cutaway plan view) and Fig. 7 (schematic longitudinal sectional view). Those with a similar structure are the most commonly used.

In FIGS. 6 and 7, the main cyclone 22 constituting the preheating cyclones C ₁ to _{C 3} has a cylindrical portion 17 whose top is covered with a ceiling plate 16, and a cylindrical portion 17.
and an inverted cone-shaped portion 18 integrally connected to the lower part of the. An inlet side gas duct 7 _b forming a part of the gas duct 7 forms an opening 19 in the upper part of the cylindrical part 17 and is connected to the cylindrical part 17 in the tangential direction or the circumferential direction. And the cylindrical part 17
A vertical outlet side gas duct _7C extending into the cylindrical portion 17 is further connected to the ceiling plate 16,
A powder discharge port 1 is provided at the lower end of the inverted conical portion 18.
8 _a is open.

When the raw material powder is supplied to the heat exchanger device 1 (see FIG. 5), which is constituted by the main cyclone 22 and the gas duct 7, the raw material powder ascends within the gas duct 7 as appropriate. The raw material particles are introduced into the main cyclone 22 from the opening 19 through the inlet side gas duct _7b while exchanging heat between the raw material powder and the exhaust gas. The exhaust gas introduced into the main cyclone 22 forms a swirling gas flow _A1 within the cylindrical portion 17 while accompanying the raw material powder. Furthermore, this exhaust gas forms a swirling gas flow within the inverted conical portion 18.
It descends in a spiral while forming A ₂ (Fig. 7).

On the other hand, the raw material powder is separated from the gas flow by centrifugal force during its descent, is pressed against the inner circumferential walls of the cylindrical portion 17 and the inverted cone-shaped portion 18, and is aggregated, causing the inner circumferential walls to The powder descends in a spiral manner and is discharged from the powder discharge port _18a at the bottom.

The gas flow from which most of the raw material powder and granules have been separated in this way is reversed near the lower end of the inverted conical portion 18, as shown in FIG.
A swirling gas flow A ₃ is again formed in the center of the gas flow A 2 and rises, and is then discharged to the outlet side gas duct 7 _C while maintaining the swirl gas flow A ₄ .

In the conventional example shown in FIG. 5, such cyclones in the heat exchange device 1 are configured to communicate in three stages in the vertical direction, and heat exchange between the raw material powder and the hot gas is repeated in sequence. This is intended to improve the heat exchange rate.

``Problem that the invention seeks to solve'' However, even if such cyclones are stacked in three stages, as in the conventional device, the powder and granules collected in each cyclone are divided into coarse raw materials and fine particles. Since the raw materials are in a mixed state, if they are placed in a lower position (on the upstream side) and fed into the inlet of the cyclone, the fine powder raw materials with small particle sizes will be mixed with coarse powder with large particle sizes. This results in heat exchange taking priority over the raw material, which means that heat exchange of the coarse raw material is not performed sufficiently. As a result, the preheating efficiency of the raw material powder in which the coarse powder raw material and the fine powder raw material are mixed is low.

Therefore, since heat exchange is relatively slow for coarse raw materials, it is possible to extend the contact time between the heated exhaust gas and the raw material powder. For example, in a powder heat exchange device as shown in Fig. 5, the gas duct between the cyclones is lengthened, or C ₁ ~
A method has been implemented in which the cyclones indicated by C ₃ are further stacked in four or five stages to improve the preheating efficiency of the raw material powder. However, when the gas duct is lengthened or when the cyclones are stacked in multiple stages, there is a problem in that the pressure loss at the cyclone or duct increases, and furthermore, the height of the entire heat exchange device increases significantly.

``Purpose of the invention'' Therefore, the main purpose of this invention is to
To provide a multi-stage heat exchange device in which fine powder can sufficiently exchange heat with each other, without reducing the heat exchange efficiency between exhaust gas in a high-temperature state and raw material powder, and which promotes compactness of the device.

Another object of the present invention is to provide a multi-stage heat exchange device that can be made smaller, thereby reducing the pressure loss generated in the duct and reducing power consumption, or improving the heat exchange processing capacity by keeping the pressure loss the same.

"Means for Solving the Problems" In order to achieve the above objective, the main means adopted by this invention is to combine multiple cyclones in multiple stages through appropriate ducts, and supply the gas rising through the ducts. In a multi-stage heat exchange device for heating or cooling raw material powder, at least one of the cyclones separates a coarse raw material from the raw material powder supplied to the cyclone, and disposes this coarse raw material in a lower part. a coarse powder separating means for separating the fine powder from the raw material powder and sending the fine powder to the inlet duct of the other cyclone. However, the coarse powder raw material is supplied upstream of the fine powder raw material when viewed in the raw material supply direction to the duct.

"Operation" The supplied raw material powder is separated into coarse raw material and fine powder raw material in the cyclone. Among these, for example, coarse powder raw materials that require a relatively long heat exchange time are placed in the lower part of the duct (as seen in the flow direction of exhaust gas), which is a high temperature part and has a long residence time before being introduced into the lower cyclone. Since the raw material is input into the upper stream (upstream side), it is heat exchanged preferentially and for a longer period of time than the fine powder raw material. This means that the required residence time of the coarse raw material in the duct is relatively shorter than that of raw material powder and granules in which fine and coarse raw materials are mixed. can be shortened.

On the other hand, fine powder raw materials that require a short heat exchange time are
Since the heat exchange with the gas (exhaust gas) ends instantly, the residence time necessary for heat exchange is sufficient even if the product is introduced into the upper part of the duct between the cyclones (downstream side as seen in the flow direction of the exhaust gas). This means, as mentioned above, that even if the duct is shortened, the fine powder raw material can be heat exchanged without any problems.

``Effect of the invention'' The required residence time of the coarse powder material in the duct is shortened, so the duct between the cyclones can be shortened, and the device can be made more compact.

Furthermore, the duct can be shortened, so
Pressure loss due to friction in the exhaust gas duct and pressure loss due to lifting of powder and granules can be reduced, and power consumption in the heat exchange device can be reduced.

Further, when the duct is used with the conventional length, the residence time of the coarse powder is sufficient, so that the heat exchange efficiency is improved.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

``Example'' Figure 1 is a system diagram of a cement raw material firing apparatus to which a multistage heat exchanger according to an embodiment of this invention is applied, and Figures 2a and b show powders of the multistage heat exchanger in Figure 1. FIGS. 3 and 4 are explanatory diagrams showing different modifications of the granule input section (chute section), and FIG. 4 shows the cyclone of the embodiment apparatus shown in FIG. 1, and FIG. The figure is the same side view.

Note that the following example is only one specific example of this invention, and the technical scope of this invention is not limited by this example. Further, the same reference numerals will be used to describe elements common to those of the conventional cement raw material firing apparatus and multistage heat exchange apparatus shown in FIG.

First, for convenience of explanation, an example of a cyclone used in the heat exchange device 1' (see FIG. 1) according to this embodiment will be shown. As shown in FIGS. 3 and 4, the main cyclone 22' is
The main cyclone 22 has almost the same structure and function as the main cyclone 22 shown in the figure.
An opening _17a is provided in the side wall of the cylindrical portion 17 on the near side (upstream side) of the opening 19 of this main cyclone 22' when viewed in the flow direction of the gas flow in the main cyclone 22'. A coarse powder collecting section 24 having a cylindrical upper part and an inverted truncated conical lower part is attached to the opening 17 _a , for example, via a short duct 23 . This coarse powder collecting section 24 constitutes the main part of the coarse powder separating means, and as described above, the main cyclone 2
This is for separating the coarse powder raw material from the raw material powder granular material swirling inside 2'.

A powder discharge port 26 is provided at the lower part of the coarse powder collecting section 24 for discharging the raw material powder (coarse powder raw material) collected thereby. The powder discharge port 26 is connected to the raw material powder chute 2 provided with a gate valve 28.
7, it is connected to, for example, a gas duct 7 connected to the inlet side of the next-stage cyclone located below.

In this case, the main cyclone 22' corresponds to the coarse powder collecting section 24 separating the coarse raw material from the raw material powder, and relatively separates the remaining raw material powder and granules as fine powder, etc. It constitutes the main part of the fine powder separation means that is to be separated. A raw material powder chute 14 is attached to the powder discharge port _18a of the main cyclone 22'. This chute 14 is also provided with a gate valve 29 similar to the raw material powder chute 27.

Here, the characteristic components of this example device will be explained. In FIG. 1, for example, the above-mentioned main cyclone 22' and coarse powder collecting section 24 are provided at the uppermost stage of the heat exchanger 1', constituting the cyclone _C1 in the figure. In this case, these raw material powder shoots 14 and 27 are transferred to the cyclone C ₂ located below the cyclone C ₁ .
and C ₃ are connected to a gas duct 7 ₂ arranged to connect them. Of these, coarse powder collection section 2
The raw material powder chute 27 of No. 4 (see Fig. 4) is connected to the raw material powder chute 14 of the main cyclone 22' (see Fig. 4).
(see figure) is connected to the upstream side as seen in the flow direction of exhaust gas.

That is, the position where this raw material powder chute 27 is connected to _the gas duct 7 ₂ is on the upstream side of the inlet side duct 7 _b of this cyclone C ₂ (as seen from cyclone C ₃ ).
Outlet side duct 7 of C ₃ (downstream side of _C ). Therefore, from the raw material powder chute 27 to the gas duct 7 ₂
The raw material powder and granules fed into the raw material powder chute 1
The raw material powder is introduced into the cyclone _C2 after a residence time longer than that of the raw material powder introduced into the gas duct ₇₂ from No.4.

Next, the functions of the embodiment heat exchange device 1' having the above-mentioned configuration will be explained. In FIG. 1, the raw material powder introduced from the powder input chute 5 rides the gas flow of exhaust gas rising in the gas duct 7, and while exchanging heat between the raw material powder and the exhaust gas, First, it heads toward the uppermost cyclone _C1 , passes through the inlet side gas duct _7b shown in FIGS. 3 and 4, and is introduced into the main cyclone 22' through the opening 19. In the cylindrical part 17 of the main cyclone 22', the exhaust gas accompanied by the raw material powder is transferred to the cylindrical part 17.
Rotate inside. Then, due to the centrifugal force accompanying this rotation, the raw material powder is urged in the direction of the side wall of the cylindrical part 17, and a part of it passes through the opening _17a provided in the cylindrical part 17 to the coarse powder collecting part 24. released.

The raw material powder discharged into the coarse powder collecting section 24 falls due to gravity and is collected at the lower discharge port 26, and then passes through the raw material powder chute 27 to the lower stage as shown in FIG. The gas is introduced into the outlet side gas duct _7C which connects the cyclones _C2 and _C3 and connects to the cyclone _C3 of the gas duct ₇₂ . The charged raw material powder goes through the above steps again and is guided to the cyclone _C2 by riding the rising gas flow while having a relatively long residence time.

On the other hand, as can be seen from Figures 3 and 4,
The raw material powder that does not enter the coarse powder collecting section 24 but descends while swirling is collected at the lower part of the main cyclone 22'. The raw material powder is taken out from the powder discharge port _18a , passes through the raw material powder chute 14, and, as can be seen from _FIG . , is introduced on the downstream side as seen in the flow direction of the gas flow. The input raw material powder and granules are together with the raw material powder and granules separately input from the raw material powder chute 27.
After going through the above steps again, it rides the rising gas flow and is guided to cyclone _C2 with a relatively short residence time.

In this way, heat exchange is performed between the raw material powder and the hot gas rising through the gas duct 7. In particular, as shown in FIGS. 3 and 4, from the inlet side gas duct _7b to the main cyclone 2 Of the raw material powder introduced into the coarse powder collecting section 24, powder with a relatively large particle size is captured. Therefore, the so-called coarse powder raw material is collected in this coarse powder collecting section 24, and this coarse powder raw material is supplied from the raw powder chute 27 to the gas duct _7a in the manner and under the conditions described above. The large-diameter granular powder, which requires a relatively long residence time during heat exchange as described above, can sufficiently perform heat exchange as described above.

On the other hand, the fine powder raw material left in the main cyclone 22' and collected is transferred to the raw material powder shoot 1.
4 to the duct 7 ₂ in the manner and under the conditions described above and heat exchanged within a substantially short period of time.

Furthermore, the coarse powder collecting section 24 has a main cyclone 22'.
Since it can be placed at any position in the circumferential direction of the side wall, the coarse powder collecting part 24 can be placed in a position close to the inlet side gas duct _7b (Fig. 1) of other cyclones placed below. This can also be implemented here without increasing the height of the heat exchange device.

Next, referring to FIG. 2ab, a modification of the powder/granular material charging chute shown in FIG. 1 will be described. In the examples shown in Figures 2a and b, unlike the method in which a mixed raw material containing coarse and fine powder raw materials is fed into the heat exchanger 1', the powder raw material and the fine powder raw material are separated in advance and then individually separated. An input method is adopted.

This _is because the _inlet side duct _7b (third
Gas ducts 7 ₁ , 7 connected to
At the stage of charging the raw material powder and granules, the heat exchange of coarse and fine powder raw materials is carried out in stages similar to the heat exchange performed in the heat exchange device 1' (Fig. 1) described above. It is.

Fig. 2a shows an example of a method in which the raw material powder is lifted up to the powder input chute 5' by mechanical force such as a conveyor or a bucket (not shown). A mechanical classifier, for example a screen 30, is provided to separate the powder into coarse raw material and fine powder.

Viewed from the flow direction of the gas flow of the screen 30 and gas duct ₇₁ , a coarse powder raw material input chute _5a ' (see Fig. 4) is connected to the upstream side thereof, and a fine powder raw material input chute is connected to the same downstream side. _5b ' (see Figure 4).

FIG. 2b shows an example of a method in which the raw material powder is lifted up to the powder input chute 5'' by air force such as an air lift (not shown).
A separation cyclone _C5 is provided to separate this raw material powder into coarse powder raw material and fine powder raw material.
The separation cyclone C ₅ may be of substantially the same type as the cyclone C ₁ used in the heat exchanger 1' described above. Therefore, also in this separation cyclone _C5 , the raw material powder chute 1
4, 27 (see Figure 4), when viewed from the direction of gas flow in the gas duct ₇₁ ,
Coarse raw material input chute 5 _a ″ connected to the upstream side
(see Fig. 4) and a fine powder raw material input chute _5b '' (see Fig. 4) connected to the same downstream side.

In addition, when the raw material powder is charged by the method _shown in _FIGS . Since the heat exchange with the cyclone is efficiently performed, the inlet duct ₇₁ of the uppermost cyclone, which is normally the longest duct in the above-mentioned heat exchange apparatus, can be shortened.

Incidentally, in the above example apparatus, a case has been described in which the cyclone _C1 provided at the uppermost stage of the heat exchange apparatus is provided with various means for separating the coarse powder raw material and the fine powder raw material. However, it goes without saying that each of these means can be similarly applied to cyclones _C2 and _C3 , which are sequentially arranged below cyclone _C1 .

As mentioned above, this invention is not limited at all to the type of powder or granular material, the type of heat exchange (heating, cooling), or the type of hot gas (combustion gas, air, etc.), and the shape of the cyclone or gas duct or It is also possible to freely change the design of the structure, arrangement, etc. of the coarse powder collecting section. For example, it is possible to arrange multiple coarse powder collecting sections for one cyclone, or to arrange the coarse powder collecting section in a cyclone. It is also possible to provide it in the inverted cone part or the ceiling plate part.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a cement raw material firing apparatus to which a multistage heat exchanger according to an embodiment of the present invention is applied, and Figs. 3 and 4 show the cyclone of the embodiment shown in FIG. 1, FIG. 3 is a plan view thereof, and FIG. 4 is the same side view. Figure 5 is a diagrammatic system diagram of a conventional cement clinker production facility that is the background of this invention, Figure 6 is a partially cutaway plan view of a cyclone according to the conventional example, and Figure 7 is It is a sectional view of the same side. Explanation of symbols, 1'... Heat exchange device, 7... Gas duct, 7 _b ... Inlet side gas duct, 7 _c ... Outlet side gas duct, 14, 27... Raw material powder chute, 22, 22'... Main cyclone , 24... coarse powder collection section, C ₁ to C ₃ ... cyclone, C ₄ , C ₅ ...
separation cyclone.

Claims (1)

[Claims for Utility Model Registration] (1) A multi-stage heat exchange device that combines a plurality of cyclones in multiple stages via appropriate ducts and heats or cools raw material powder supplied to gas rising in the ducts, comprising: At least one of the cyclones
Coarse separation means separates coarse raw material from the raw material powder supplied to this cyclone and sends this coarse raw material to the inlet side duct of another cyclone arranged below, and separates fine powder from the raw material powder. and fine powder separating means for separating and sending the fine powder raw material to the inlet side duct of the other cyclone, the coarse powder raw material being smaller than the fine powder raw material when viewed in the raw material supply direction to the duct. A multi-stage heat exchange device that is supplied to the upstream side. (2) The fine powder separating means includes a main cyclone connected to a lower part of the chute for discharging the fine powder raw material and having openings around the side wall or the ceiling and approximately in the center of the ceiling, and the coarse powder separating means Claim for Utility Model Registration, wherein the means comprises a coarse powder collection chamber connected to an opening formed around the side or ceiling surface of the main cyclone and provided with a chute at the bottom for discharging coarse powder raw materials. A multi-stage heat exchange device according to scope 1.