JPS58199754A - Powder body preheating method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preheating powder and granular material and an apparatus for carrying out the method.

BACKGROUND ART Conventionally, in furnaces for heating and firing powder and granular materials such as cement raw materials, cyclone suspension preheaters have often been employed as powder and granular material preheating devices for the purpose of saving thermal energy. The reason for this is that it has many advantages compared to other preheaters, such as its simple structure and easy scale-up.

The suspension preheater tf has a function of heat exchange between gas and powder and a function of separation, and is configured by combining one or more units. The heat exchange performance is improved by making the units multistage and increasing the number of heat exchanges. However, it is necessary to consider both the advantage of reducing fuel costs due to rounding and multi-stage cyclones, which have a large pressure loss, and the disadvantage of increased power energy due to increased pressure loss. From this point of view, a four-stage cement kiln is usually used.

On the other hand, recently, research has been conducted to reduce pressure loss in cyclones, and trickle cyclones, horizontal cyclones, etc. have been developed and are being put into practical use.

However, although these cyclones have reduced pressure loss compared to conventional cyclones, their structures are more complex and there is a strong possibility of intermelting occurring in stable operation. In addition, it had many drawbacks, such as the fact that its pressure loss reduction effect was not significant.

Furthermore, a device has been proposed in which heat exchange is performed by causing the gas and powder particles flowing upward through a vertical heat exchanger having multiple narrow parts to flow in opposing vortices (Kokusho 46-224807
According to this device, the gas itself becomes a vortex flow, so the pressure loss is large and the inclination angle of the inclined part is small, so there are six drawbacks: powder and granules accumulate on the side of the heat exchanger. .

The present invention has been made to solve the above-mentioned drawbacks of the prior art. Gas is introduced in the form of a jet upward from the bottom into a container having an expanding slope, and the gas velocity is increased as the gas velocity increases toward the top. The powder and granules are introduced into the gas flow from the side of the container, and the powder and granules are accelerated in the lower part and decelerated in the upper part. forming a heat exchanger between the gas and the granular material, the gas is discharged from the ceiling of the container to the outside of the container, and is connected to the side wall and is provided with an IIl or a plurality of separation tubes; The present invention provides a method for preheating a powder or granule material, characterized in that the powder or granule material is discharged from the bottom of a separation tube, and a device for carrying out the method. Nine embodiments shown in the attached drawings are referred to below. The present invention will be explained below.

Figures 1 (A) and (B) show the unit of the apparatus used in the method for preheating powder and granular material of the present invention, and Figure 1 (B) shows the D
- It is a sectional view of D' section. The unit consists of a heat exchanger and four separation tubes. 1 is a heat exchanger, 2 is a separation tube, 3
is a gas inlet, 4 is a powder inlet, 5 is a powder transfer port,
6ti gas outlet.

The heat exchanger 1 is equipped with an enlarged slope portion L- formed by a sloped side wall 8, and is configured such that the slope αl of the side wall 8 is not less than 55° in order to prevent the accumulation of powder particles. Moreover, the gas velocity at the upper part 8' of the enlarged inclined portion is configured to be 1/2 or less of the gas velocity at the gas introduction port 3. The gas inlet 3 forms a constriction 9, and the illustrated one has a throat shape.

The powder inlet 4 is provided at a predetermined location on the side wall 8. The granular material transfer port 5 is an outlet for the raw material heat-exchanged in the heat exchanger 1, and is also an inlet for the granular material into the separation tube 2.

The gas exhaust hole 6Fi is provided on the ceiling part 9 of the enlarged inclined part.

FIG. 2 shows another example of the embodiment shown in FIG.
The same reference numerals as in the figure indicate the same parts. This embodiment differs from the embodiment shown in FIG. 1 in that the separation tube is provided in the middle of the inclined portion of the side IR8.

Figure 3 shows the top unit, 10 is a heat exchanger, 1
1 is a gas inlet, 12 is a powder inlet, 13 is a gas transfer port, 14 is a Fi gas outlet, 15 is a cyclone, and 16 is a powder outlet.

The heat exchanger 10Fi has an enlarged slope formed by a sloped side wall 17, and the slope α? is configured such that the angle is not less than 55°, and the gas velocity at the upper portion 17' of the enlarged inclined portion is configured to be 172 degrees or less of the gas velocity at the gas inlet 11. Forming the gas inlet 11Fi constriction part i
The one shown has a throat-like structure. One or more powder introduction ports 12 are provided at predetermined locations on the side wall 17 .

In the embodiment shown in FIGS. 1 and 2 above, the granular material entering from the granular material inlet 4 (solid line arrow AJ in the figure) is connected to the upward gas from the gas inlet 3 (dotted line arrow B in the figure). join together.

Gas B passes through the throat at a speed of 15 to 40 rrms, merges with the powder particles, and forms a spouted bed C within the expanding slope.

By adjusting the speed of the throat gas flow,
It is preferable to prevent the powder from falling to the lower part from the throat part.

In the spouted bed C, the powder and granules are moved up and down by the upward jet of gas, and the powder and granules are accelerated many times by the gas flow. The heat exchange between gas B and powder A is
This occurs particularly violently when the powder or granules are accelerated by the gas flow, so that efficient heat exchange takes place in the spouted bed. Note that even with the conventional method, if the powder particles can be uniformly dispersed in the gas, heat exchange should be performed with the same efficiency as the present invention, but in actual equipment, it is difficult to uniformly disperse the powder particles was extremely difficult and made efficient heat exchange impossible. Furthermore, by setting the inclination α of the enlarged inclined portion of the heat exchanger to 55° or more, the powder particles do not accumulate on the side walls, facilitating the formation of a spouted bed, and improving the efficiency of heat exchange.

Generally, in a gas-powder mixture, increasing the solid-gas ratio will result in
When the solid-gas ratio is low, what behaves as a single particle becomes
They tend to behave as a group of particles, and appear to function in the same way as coarse particles.

In the above embodiment, the spouted bed C is formed in the heat exchanger, thereby increasing the solid-air ratio (that is, increasing the powder and granule concentration), so that the powder and granules in the spouted bed near the side wall are apparently coarse particles. Therefore, by providing a separation tube on the upper side wall of the granular material that has undergone heat exchange, it becomes possible to separate the gas from the granular material with almost no pressure loss. Further, it is preferable to provide an aerodynamic device such as a flap damper on the discharge chute connected to the discharge port in order to prevent the powder from being re-scattering due to the backflow of gas.

Conventional cyclones require increasing the cyclone inlet wind speed to increase their separation efficiency, and the pressure drop increases significantly. Therefore, the final stage cyclone had a separation efficiency of around 95% for waste gas treatment and dust treatment, and the cyclone for murder had no choice but to limit the separation efficiency to 60 to 90%. Conventional cyclones apply centrifugal force to particle groups to break them up and transport them to the wall, slowing down the gas velocity and causing the particles to settle. moreover,
In a heat exchanger that uses opposed vortices, the gas itself becomes a vortex, resulting in a large pressure loss, and powder and granules accumulate on the side walls of the heat exchanger, reducing heat exchange efficiency. It was hindering me.

In the present invention, multiple stages of heat exchangers can be provided vertically by connecting the gas discharge port of the lower stage heat exchanger to the gas inlet of the heat exchange section of the upper stage heat exchanger, and the structure of the separation tube is simple. The heat exchange part and separation tube are integrated, allowing for a self-supporting structure, and since a cyclone separator is not used, pressure loss is small.

As described above, in the present invention, the heat exchanger has a jet function, and the granular material is repeatedly accelerated by the gas flow to perform heat exchange, so that the heat exchange performance is superior to the conventional air flow method. First, the separation tube for powder and gas utilizes the agglomeration effect (particle clustering) of powder and granule, without using the separation effect of gas and powder by centrifugation, resulting in high separation efficiency. can be obtained with low pressure loss. Furthermore, the structure of the heat exchanger is simple.

FIGS. 4(+) to fc) show other embodiments of the heat exchanger that can be used in the present invention.

This figure (a) shows a type in which the gas inlet 3 is shaped like an orifice and the ceiling part is circular, (bl is a type in which the gas inlet is made into a throat shape and the ceiling part 9 is circular, and (C) shows the type in which the ceiling part is circular. It is a type in which the part 9 is flattened and the gas inlet 3 is shaped like an orifice.

4. Efficient heat exchange and separation can be performed using any of the above embodiments.

A multistage preheater to which the method for preheating powder or granular material of the present invention is applied is shown in FIGS. 5 and 6.

In Fig. 5, 11-14ti heat exchanger, 21-24
19 is a separation tube, 19 is a rotary kiln, and 20 is a connecting duct. In the figure, solid line arrows indicate the behavior of the powder and granular material, and dotted line arrows indicate the gas flow.

Further, a burner and a cooler bleed duct can be provided in the heat exchanger at the lowest stage of the multistage preheater shown in FIG. 5, so that it can function as a calcining furnace. In this case, one more heat exchanger will be added.

In FIG. 6, the same numbers as in FIG. 5 indicate the same parts.

In the figure, the gas inlet at the bottom of the multi-stage preheater is connected to the upper gas outlet of the cyclone of the device disclosed in Japanese Patent Application No. 51-81344, where 21 is the throat portion and n is the burner. , 23 is a calcining furnace, 24 is a secondary air inlet, 5 is an enlarged space section, and an opening cyclone.

In the above embodiment, an electrostatic precipitator (not shown) may be attached to the uppermost separation tube 21.

The device of the above embodiment has various advantages over the conventional cyclone type suspension preheater, such as high thermal efficiency, extremely low pressure loss, simple structure, and easy arrangement of the device.

According to the present invention, it is possible to provide a method and apparatus for preheating powder or granular material with a simple structure and extremely low pressure loss.

[Brief explanation of the drawing]

Figures 1 (A) and (B), Figures 2 and 3, (Figures 3 and 3 are cross-sectional views and vertical cross-sectional views of the powder and granular material preheating device according to the present invention, and Figure 4 1a) to fc) are 1 is a cross-sectional view of an embodiment of a heat exchanger; FIG. FIG. 5 is an elevational view when the present invention is applied to a multistage preheater, and FIG. 6 is an elevational view when the present invention is applied to a multistage preheater with a calcining furnace. 1.10... Heat exchanger, 2.15...
Separation tube, 3.11... Gas inlet, 4.12... Powder inlet, 5.13... Powder transfer port, 6.14. ... Gas discharge port, 7.16 ... Powder discharge port, 8.17 ... Side wall, 19 ... Rotary kiln, 20 ...・Connection duct, n...Calcination furnace, 4...Fuel burner. Figure 1 (A) (B) Figure 2 (A) (B)

Claims (7)

[Claims] (1) Gas is introduced into the container in the form of a jet upward from the bottom, and the gas velocity is reduced upward by a 9-enlarged slope section formed in the container, and the gas flow is introduced from the side of the container. Powder is introduced, the powder is accelerated in the lower part, decelerated in the upper part, and a part of it settles to form a spouted layer on the expanding slope, thereby causing the gas and the powder to preheating of powder and granular material, characterized in that the gas is discharged from the ceiling of the container, while the powder and granular material is discharged from one or more separation pipes connected to the side of the container. Method. (2) The method for preheating a granular material according to claim 1, wherein the heat exchange and separation between the granular material and the gas are performed in multiple stages. (3) Small diameter gas inlet at the bottom, powder inlet at the side,
A unit comprising a heat exchanger having a gas discharge port at the top and an expanding slope extending upward from the gas inlet, and a separation pipe connected to the upper side wall of the heat exchanger. Powder preheating device. (4) Connect the gas outlet of the heat exchanger to the lower gas inlet of the upper heat exchanger, and connect the lower outlet of the upper separation tube to the powder inlet of the lower heat exchanger to complete the unit. A powder preheating device according to claim (3), which is formed by connecting multiple stages. . (5) Connect the gas outlet of the heat exchanger to the lower gas inlet of the upper heat exchanger, and connect the lower outlet of the upper separation tube to the powder inlet of the lower heat exchanger to complete the unit. A granular material preheating device according to claim (3) or (4), which is formed by connecting multiple stages. (6) The powder preheating device according to claim (4) or (5), wherein the separation device of the uppermost unit is a cyclone separator. (7) The granular material preheating device according to claim (4) or (5), wherein the unit calcining furnace and/or the lowermost unit are connected to a firing furnace.