JPH0351995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a calcination device for powder raw materials such as cement raw materials, and more particularly to a calcination device for overcoming operational problems that occur when starting up the calcination device. First of all, Fig. 1 is a diagrammatic system diagram of the entire raw material powder sintering apparatus to which the above-mentioned spouted bed type calcination apparatus is applied, in which combustion air from the cooling device is used as the gas for forming the spouted bed, and Fig. 2 is This is _an enlarged side view _of the calcination device part in FIG. The calcining apparatus is composed of a separation cyclone _C4 attached to the calcining furnace 2, and the details of the calcining furnace 2 are shown in FIG. Further, 3 is a baking device such as a rotary kiln, 4 is a cooling device that cools red-hot clinker discharged from the baking device, 6 _b is a fuel supply device attached to the baking furnace 3, and 8 is a cooling device 4 → calcination. Furnace 2
→ Separation cyclone C ₄ → Induced draft fan for inducing hot gas flow in preheating device 1, 10 is cooling device 4
This is a forced air blower.

As shown in Fig. 2, the calcining furnace 2 is formed by arranging a mixing chamber 2 _b and a combustion chamber _a above and below, respectively, with an intermediate constriction part 2 _c as a boundary, and the lower end of the combustion chamber 2 _a is formed in the shape of an inverted truncated cone. A spouted bed of raw material powder is formed inside the calciner 2 by the gas induced to rise through the gas inlet 2 _d opened at the lower part of the calciner 2 , and a fuel supply device 6 _a disposed near the lower end of the combustion chamber 2 _a After the raw material powder is calcined by supplying fuel into the collection of raw material powder flowing in a jet state, the raw material powder is fed from the mixing chamber _2b through the combustion gas conduit 17 to the separation cyclone _C4 attached to the calciner 2. This is a spouted bed type calcination device with a discharge method, and this type of calcination device has excellent characteristics in both the combustion performance of the supplied fuel in the calcination furnace 2 and the performance of calcination of the raw material powder. Therefore, it has been increasingly used in recent years.

In such a spouted bed type calciner 2, exhaust gas from the calciner 3 is exclusively used as a spouted bed forming gas that is induced to rise through a conduit _{13 connected to a gas inlet 2d at} the lower end of the combustion chamber 2a. (), when the combustion air from the cooling device 4 following the firing furnace 3 is used exclusively () (as shown in FIGS. 1 and 2), and when the exhaust gas from the firing furnace 3 and the cooling device 4 are used exclusively. There are three types: () when using a mixed gas with combustion air from Among these methods, in the methods () and (), in which firing furnace exhaust gas is used as at least part of the gas for forming the spouted layer, it is necessary to place the calcining furnace 2 near directly above the firing furnace inlet end cover 12. Lack of freedom in terms of equipment placement. On the other hand, in the method () in which the combustion air from the cooling device 4 is exclusively used as the gas for forming the spouted layer, there is flexibility in the relative arrangement of the calciner 2 and the calciner inlet end cover 12. In particular, even when additionally installing the calcining furnace 2 to the existing preheating device 1, the placement of the calcining furnace 2 is relatively free, and even if the calcining device including the preheating device 1 and the calcining furnace 3 continues to operate, Since the installation work of the kiln 2 can be carried out, there is an advantage that the downtime period of the kiln equipment accompanying the installation work can be shortened.

The exhaust gas from the firing furnace 3 is passed through the firing furnace exhaust gas conduit 1.
4 through the middle part of the calciner 2, for example the mixing chamber 2 _b
The combustion gas is introduced into the lower end of the calciner 2, mixed with combustion gas from the combustion chamber _2a of the calciner 2, and then discharged to the separation cyclone _C4 . At this time, the exhaust gas from the firing furnace 3 is at a high temperature of 1,000 to 1,200°C, and if this continues, the dust of the raw material powder contained in the exhaust gas will cause coating on the inner wall of the firing furnace exhaust gas conduit 14.
By supplying a portion of the preheated raw material powder from the lowermost stage powder separator C ₃ of the preheating device 1 to the firing furnace exhaust gas conduit 14 through the chute 15 _b , the temperature of the firing furnace exhaust gas is lowered and the occurrence of the coating is prevented. At the same time, it is designed to effectively utilize the sensible heat of the firing furnace exhaust gas.

The spouted bed type calcination device 2' which uses the combustion air from the cooling device 4 as the gas for forming the spouted bed has not only excellent fuel combustion performance and raw material powder calcination performance as described above, but also Although this method is highly flexible in terms of the arrangement of the calciner, there is a problem in that the operability is poor during the transition stage from the start of operation of the calciner 3 until it reaches a steady state, as described below.

(a) Poor combustibility of fuel The raw material powder fed into the preheating device 1 from the raw material supply chute 5 at the start of operation passes through the preheating device 1 and the calcining device 2' in about tens of seconds and is fired. The raw material powder is supplied to the inlet end of the furnace 3, but it takes several minutes before the raw material powder rolls from the inlet end to the downstream side, is fired, and is discharged from the outlet end to the cooling device 4. During this time, there is no heat source in the cooling device 4, so the combustion air introduced from the lower end of the combustion chamber 2a of the calciner ₂ through the high temperature air conduit 13 is at room temperature, and the cooling device 4 After the fired products begin to be discharged, a considerable amount of time is required until the high temperature combustion air is recovered and introduced into the calciner 2.

During this period, low-temperature combustion air must be used in the calciner 2, but since the raw material powder is flowing in the calciner 2, the combustion atmosphere temperature is relatively low at around 900℃, and the flame Slow combustion occurs without any combustion. Therefore, the combustibility of the fuel supplied from the fuel supply device _6a into the combustion chamber _2a is very unstable at the beginning of operation, and sometimes misfires occur, which is dangerous.

(b) Some of the raw powder falls from the lower end of the calciner.

Operation At our company, the amount of gas passing through each part is small and the adjustment is insufficient, so the fuel supply device 6
Since it is not possible to increase the amount of combustion air introduced from the lower end of the _calciner 2 due to the risk of the combustion of the fuel supplied from a being blown out, some of the raw material powder flowing in the calciner 2 flows through the high temperature air conduit. 13 and accumulates in the high temperature air conduit 13, which narrows the cross-sectional area of the air passage of the high temperature air conduit 13, resulting in an increase in pressure loss,
In some cases, this may lead to blockage. Furthermore, since the raw material powder that has fallen and accumulated in the high-temperature air conduit 13 is at a high temperature, the work to remove it is dangerous and difficult.

(c) Distribution control of the preheated raw material is complicated. The preheated raw material from the preheating device 1 is distributed and supplied to the calciner 2 and the calciner exhaust gas conduit 14 through the preheated raw material chute 15 _a and 15 _b that are branched in the middle. However, at the beginning of operation, the operating conditions such as the amount of fuel burned in the calciner 2 and the amount of exhaust gas from the calciner 3 are not stable, so it is necessary to constantly adjust the distribution ratio of the preheated raw materials. However, the control operation is complicated. That is, when the amount of preheated raw material supplied to the calcination furnace 2 is large and the amount of supply to the calcination furnace exhaust gas conduit 14 is small, the inside of the calcination furnace exhaust gas conduit 14 becomes high temperature and coating occurs on its wall surface. On the other hand, if the amount of supply to the calcination furnace 2 is small and the amount of supply to the calcination furnace exhaust gas conduit 14 is large, the inside of the calcination furnace 2 will become high temperature and the furnace wall will be burnt out, and the calcination furnace exhaust gas will Since the raw material powder supplied in large quantities to the conduit 14 is introduced into the middle part of the calciner 2 together with the calciner exhaust gas, the residence time in the calciner 2 is short and the powder is separated without being sufficiently calcined. It will be discharged to cyclone C ₄ , reducing the calcining performance and at the same time
This may cause disturbances in driving.

Therefore, the present invention aims to solve various operational problems that could not be solved with the conventional calcining equipment as described above, and the gist of the present invention is to The calcining furnace disposed between the preheating device and the calcining furnace is formed by a mixing chamber and a combustion chamber that communicate vertically with the intermediate constriction as a boundary, and the lower end of the combustion chamber is shaped like an inverted truncated cone. A combustion air inlet is opened in the lower part of the combustion chamber, and a fuel supply device is disposed near the lower end of the combustion chamber, and a separation cyclone is attached to the mixing chamber via a combustion gas conduit. Connect the gas outlet of the separation cyclone to the preheating device via the exhaust gas pipe,
In addition, in a raw material powder calcination device in which a raw material powder discharge port at the lower end of the separation cyclone is connected to a calcining furnace inlet end cover via a calcining raw material chute, a lower part of the combustion chamber is located below the combustion air inlet. An air inlet with an enlarged diameter is provided, and a high temperature air conduit from a cooling device is connected to the side wall of the inlet in a substantially radial direction,
The lower end of the air introduction chamber is formed into a hopper shape and is connected to the inlet end cover of the firing furnace through a raw material chute, and the inlet end cover and the vicinity of the lower end of the combustion chamber are communicated through a combustion furnace exhaust gas conduit. The point is that the preheated raw material chute from the preheating device is connected to the furnace exhaust gas pipe.

Next, with reference to FIG. 3, an embodiment embodying the present invention will be described to provide an understanding of the present invention. FIG. 3 is a side view of a calcining apparatus according to an embodiment of the present invention. Note that the same reference numerals will be used to describe the same elements as those shown in FIGS. 1 and 2.

In Fig. 3, below the combustion chamber _2a provided in the lower stage of the calciner 2, there is a combustion chamber _2a and an air inlet _2d.
An air introduction chamber 2 _f is provided which communicates with the air introduction chamber 2 f through the air introduction chamber 2 f. The air introduction chamber _2f has a larger diameter than the air introduction port _2d , and a high temperature air conduit 13 from the cooling device 4 is connected to the side wall thereof in the radial direction. The lower end of this air introduction chamber _2f is formed into a hopper shape and is connected to the raw material chute _16a .
The raw material chute _16a is the inlet end cover 12 of the firing furnace 3.
It is connected to the.

In addition, the inlet end cover 12 of the combustion furnace 3 and the vicinity of the lower end of the combustion chamber _2a are connected by a firing exhaust gas conduit _14a , and the high temperature firing furnace exhaust gas is supplied to the vicinity of the combustion part of the combustion chamber _2a . , the lower end of the preheating raw material chute ₁₅ connected to the lowermost cyclone C3 constituting a part of the preheating device 1 is connected to the combustion furnace exhaust gas conduit 14.
It is connected near the lower end of _a .

It should be noted that the preheated raw material chute 15 is branched from the middle as shown by the broken line, and passes through a branch chute 15 _a .
A part of the preheated raw material may be distributed to the combustion chamber _2a of the calciner 2.

Therefore, in the apparatus shown in FIG. 3, high-temperature air flowing from the cooling device (shown in FIG. 1) 4 through the high-temperature air conduit 13 into the air inlet _2f in the radial direction passes through the air inlet _2d . It flows into the furnace 2, passes through the combustion chamber _2a and the mixing chamber _2b , and then flows into the combustion gas conduit 17.
After that, it enters separation cyclone _C4 . The combustion gas separated from the raw material powder in the separation cyclone _C4 flows into the lowermost cyclone _C3 of the preheating device through the duct 7, and is further drawn to the upper cyclone.

On the other hand, the raw material powder that is being preheated and supplied from the raw material chute 5' to the duct 7 is accompanied by the combustion gas rising in the duct 7 and transported to the cyclone _C3 , where it is separated from the combustion gas by the centrifugal force accompanying the swirling motion. Separated and collected. The raw material powder thus separated from the combustion gas is supplied into the firing furnace exhaust gas conduit _14a through the preheated raw material chute 15. In the firing furnace exhaust gas conduit 14a, high-temperature combustion exhaust gas from the firing furnace 3 flows toward the combustion chamber 2a of the calcining furnace ₂ , and the raw material powder riding on this combustion exhaust gas flows inside the combustion chamber _2a . released into the rising hot air,
Here, the fuel supplied from the fuel supply device _6a is heated and calcined by combustion, and is blown up into the mixing chamber _2b , and further flows into the separation cyclone _C4 .
The calcined raw material is supplied to the firing furnace 3 via the calcined raw material chute 16.

Further, among the raw material powder that has flowed into the combustion chamber _2a , the raw material powder that has fallen into the air introduction chamber _2f through the air introduction port _2d is discharged to the firing furnace 3 through the raw material chute _16a .

In this way, in the above embodiment, the firing furnace exhaust gas conduit 14 _a is connected to the vicinity of the lower end of the combustion chamber 2 _a of the calcining furnace 2 where the fuel supply device 6 _a is installed.
The combustion chamber 2 _a of the calciner 2 is maintained at a relatively high temperature even at the beginning of operation by the calciner exhaust gas introduced through the calciner exhaust gas conduit 14 _a , and is supplied into the combustion chamber 2 _a from the fuel supply device 6 _a . The combustion state of the fuel used is always stable, and misfires never occur.
It is preferable that the fuel supply device _6a be installed at a location that is approximately at the same level as the connection location of the firing furnace exhaust gas conduit _14a and has a relatively high oxygen concentration.

Further, an air introduction chamber 2 _f whose diameter is larger than that of the combustion air introduction port is provided below the combustion chamber 2 _a , and the combustion air is supplied to the air introduction port 2 _d at the lower end of the combustion chamber 2 _a .
Since the raw material powder can rise and flow uniformly into the combustion chamber _2a through the combustion chamber 2a, it is possible to prevent the raw material powder from falling from the lower end of the combustion chamber _2a . In particular, a hot air conduit 13 from the cooling device 4 is connected approximately radially to the side wall of the air introduction chamber 2 _f and, as in the case of a tangential connection, to the air introduction chamber 2 _f and the calciner combustion chamber 2 _a. Since no vacuum is formed in the center of the tube, it is effective in preventing the raw material powder from falling. Moreover, even if the raw material powder falls into the air introduction chamber _2f , the lower end of the introduction chamber _2f is formed into a hopper shape and is connected to the kiln inlet end cover 12 via the raw material chute _16a . Therefore, the fallen raw material powder can be discharged to the firing furnace 3 by gravity.

Furthermore, in the conventional system, the combustion section of the calciner 2 and the calciner exhaust gas conduit _14a were arranged in parallel when viewed in the flow direction of the combustion gas, whereas in the arrangement according to the present invention, the combustion part of the calciner 2 and the calciner exhaust gas pipe 14a are arranged in parallel. The raw material powder is introduced into the combustion section of the calciner 2 and flows inside the calciner 2 in a mixed state with the combustion gas from the calciner 2. Most of the raw material powder supplied to the calciner 2 is first passed through the calciner It is configured to be introduced into the exhaust gas and then introduced into the combustion section of the calciner 2 together with the calciner exhaust gas. Therefore, the firing furnace exhaust gas is always kept at a sufficiently low temperature by the large amount of raw material powder, no coating is generated on the wall surface of the firing furnace exhaust gas conduit _14a , and the total amount of raw material powder introduced into the firing furnace exhaust gas is maintained at a sufficiently low temperature. Since it is introduced into the combustion chamber 2 _a of the calciner 2 together with the calciner exhaust gas,
There is no risk of burning out the furnace wall of the combustion chamber _2a due to insufficient raw material powder in the combustion chamber _2a . In addition, after the raw material powder sufficiently absorbs the sensible heat of the firing furnace exhaust gas, it is further given heat in the calcination furnace 2, so that the heat utilization efficiency of the firing furnace exhaust gas is high, and at the same time, the raw material powder can be calcined to a high degree. I can do it. A portion of the raw material powder can be directly supplied to the calcination furnace 2 through the preheated raw material chute _15a shown by the broken line, but in this case as well, a sufficient amount of the raw material powder is supplied to the calcination furnace exhaust gas conduit _14a . Therefore, there is no particular need to control the distribution of preheated raw materials even at the beginning of operation.

As described above, the present invention includes a calcination furnace disposed between a preheating device and a calcination furnace when viewed in the direction of flow of raw material powder, and a mixing chamber and a combustion chamber that communicate vertically with the intermediate constriction section as a boundary. The lower end of the combustion chamber is formed in the shape of an inverted truncated cone, and an inlet for combustion air is opened at the lower part of the combustion chamber, and a fuel supply device is disposed near the lower end of the combustion chamber. A separation cyclone is attached via a combustion gas conduit, and the gas outlet of the separation cyclone is connected to a preheating device via an exhaust gas conduit, and the raw material powder outlet at the lower end of the separation cyclone is connected via a calcining raw material chute. In the calcination device for raw powder, which is connected to the end cover of the inlet of the calcination furnace, an air introduction chamber having a diameter larger than that of the combustion air inlet is provided below the combustion chamber, and a side wall of the air introduction chamber is provided with an air introduction chamber having a diameter larger than that of the combustion air inlet. The high-temperature air conduit is connected approximately in the radial direction, and the lower end of the air introduction chamber is formed into a hopper shape and connected to the inlet end cover of the firing furnace via the raw material chute, and the inlet end cover and the lower end of the combustion chamber are connected. This is a raw material powder calcination device characterized by communicating with a firing furnace exhaust gas conduit and connecting a preheating raw material chute from a preheating device to the firing furnace exhaust gas conduit. Operational problems such as possible deterioration of combustibility in the calciner, falling of raw material powder from the lower end of the calciner, and complicated distribution control of preheated raw materials have been eliminated. This significantly improves the operability of calcining equipment for raw powder.

[Brief explanation of drawings]

Figure 1 is a diagrammatic system diagram of the entire conventional raw material powder firing equipment that uses combustion air from a cooling device as the gas for forming the spouted bed, and Figure 2 is an enlarged view of the calcination equipment part in Figure 1. FIG. 3 is a side view of a calcining apparatus according to an embodiment of the present invention. (Explanation of symbols), 1... Preheating device, 2... Calcining furnace, 2'... Calcining device, 2 _a ... Combustion chamber, 2 _b ...
Mixing chamber, 2 _d ... Air introduction port, 2 _f ... Air introduction chamber, 3... Firing furnace, 4... Cooling device, 6 _a ... Fuel supply device, 12... Inlet end cover, 13... High temperature Air conduit, 14, 14 _a ...Calcining furnace exhaust gas conduit, 1
5...Preheating raw material chute, 16...Calculating raw material chute, _C4 ...Separation cyclone.

Claims (1)

[Scope of Claims] 1. A co-current calciner disposed between a preheating device and a calciner when viewed in the direction of flow of raw material powder, and a mixing chamber and a combustion chamber that communicate vertically with an intermediate narrowing section as a boundary. The lower end of the combustion chamber is formed into an inverted truncated cone shape, and an inlet for combustion air is opened at the lower part of the combustion chamber, and a fuel supply device is disposed near the lower end of the combustion chamber, and a mixing A separation cyclone is attached to the chamber via a combustion gas conduit, the gas outlet of the separation cyclone is connected to a preheating device via an exhaust gas conduit, and a raw material powder outlet at the lower end of the separation cyclone is connected to a calcined raw material chute. In the calcining device for raw powder, each of which is connected to the end cover of the inlet of the firing furnace through the The high-temperature air conduit is connected in a substantially radial direction, and the lower end of the air introduction chamber is formed into a hopper shape and connected to the kiln inlet end cover via the raw material chute, and the inlet end cover and the fuel supply device are connected to each other through the raw material chute. A calcination device for raw material powder, characterized in that the vicinity of the lower end of a combustion chamber in which a combustion chamber is arranged is connected to the vicinity of the lower end of the combustion chamber through a calcination furnace exhaust gas conduit, and a preheated raw material chute from a preheating device is connected to the calcination furnace exhaust gas conduit. 2. The calcination device for raw material powder as set forth in claim 1, wherein the preheating raw material chute connecting the preheating device and the calcination furnace exhaust gas conduit is branched and connected to the calcination furnace.