JP6362219B2 - Gas cooling method and apparatus - Google Patents

Description

  The present invention relates to a gas cooling method and apparatus, and more particularly, to a gas cooling method used in a chlorine bypass system or the like for extracting chlorine from a kiln bottom of a cement kiln to remove chlorine. .

  Conventionally, a chlorine bypass system is used to remove chlorine that causes problems such as blockage of a preheater in a cement manufacturing facility. In addition, with the recent increase in the amount of chlorine-containing recycled resources used, the amount of chlorine brought into the cement kiln has increased, making it impossible to increase the capacity of the chlorine bypass system.

  In this chlorine bypass system, in order to extract a part of the combustion gas from the vicinity of the inlet hood of the cement kiln, a probe projects from the vicinity of the inlet hood, and an extraction gas processing facility is provided downstream of the probe. Since the tip of the probe is exposed to a high temperature of about 1000 ° C. near the entrance hood, it is necessary to protect the probe from thermal damage. Moreover, since the installation space of the probe in the entrance hood is limited, it is desired to reduce the size of the probe.

  Therefore, Patent Document 1 discloses an inner cylinder through which a high-temperature combustion gas flows, an outer cylinder surrounding the inner cylinder, a low-temperature gas discharge port formed in the inner cylinder, and an inner cylinder and an outer cylinder. There has been proposed a combustion gas extraction probe comprising a low-temperature gas supply means for supplying a low-temperature gas to a discharge port and discharging a low-temperature gas in the direction perpendicular to the suction direction of the high-temperature combustion gas.

  In the chlorine bypass system, the extraction gas is rapidly cooled to about 350 ° C. or less directly by the probe, so that volatile components such as chlorine in the extraction gas are efficiently concentrated in the fine powder portion of the bypass dust. However, in order to avoid an increase in the size of the probe due to the increase in the size of the chlorine bypass system in recent years, as described in Patent Document 2, a two-stage direct cooling system is adopted, and the extraction gas is set to 450 ° C. to 550 ° C. with the probe. After cooling, cooling to about 350 ° C. in the second stage is also performed.

Japanese Patent No. 4744299 JP 2011-056434 A

  Even in the cooling of the extraction gas in the second stage of the chlorine bypass system, the cooling method having a high chlorine removal capability described in Patent Document 1 can be applied. Since the flow rate of the extraction gas is increased in order to suppress the increase in the pressure loss due to the small amount, the cooling capacity tends to decrease.

  On the other hand, in order to increase the capacity of the chlorine bypass system, in order to keep the equipment cost low, after the extraction gas is cooled by a probe and direct cooling in two stages, the extraction gas processing facility is branched and the branch system is added in stages. It corresponds by that. Therefore, the extracted gas after direct cooling is subjected to solid-gas separation processing in each branch system. From the viewpoint of equipment protection, the cooling air volume is controlled so that the extracted gas is about 350 ° C. or less in all branch systems. Yes.

  However, the cooling air flow tends to increase directly due to the decrease in the cooling capacity. Therefore, when the amount of extracted gas decreases or the fan speed is increased to compensate for this, the amount of chlorine bypass exhaust gas increases, and the heat loss increases when the exhaust gas is returned to the preheater attached to the cement kiln. There was a problem. In order to avoid this, it is conceivable to discharge the low temperature gas while controlling the temperature of the extraction gas in each of the branch systems, but there is a system that controls the amount of the low temperature gas corresponding to the drift of the combustion gas that changes every moment. This is necessary and leads to an increase in equipment cost and operation cost.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and an object thereof is to provide a method and an apparatus for efficiently cooling a gas at a low cost.

  In order to achieve the above object, the present invention is a gas cooling method for discharging a low temperature gas into a flow of the high temperature gas on the same plane substantially perpendicular to the flow direction of the high temperature gas. A plurality of discharge ports for dividing the region near the same surface where the plurality of discharge ports exist in the flow of the high-temperature gas into a plurality of independent flow paths, and each of the divided flow paths The low temperature gas is discharged from each of the discharge ports to cool the high temperature gas.

  According to the present invention, by discharging the low temperature gas to each of the divided flow paths having a reduced diameter, the mixing with each high temperature gas flowing through the divided flow paths is improved, so that the high temperature gas is efficiently cooled. can do. In addition, since the high-temperature gas is cooled in the divided flow path and then merged on the downstream side of the divided flow path, even if a temperature difference occurs between the divided flow paths, the temperature is uniform, and the cooled gas flows into the subsequent stage. Even when the processing system is branched, it is not necessary to control the amount of low-temperature gas for each branch system, and an increase in equipment cost or the like can be avoided. Furthermore, since only the region in the vicinity of the same surface where there are a plurality of discharge ports is divided, the pressure loss can be minimized.

  In the gas cooling method, the plurality of discharge ports are provided in a plurality of stages along the high-temperature gas flow, and only a region near the plurality of discharge ports on the most downstream side of the high-temperature gas is formed into a plurality of independent flow paths. Can be divided. Accordingly, it is possible to cope with a case where the gas processing system after cooling branches downstream of the plurality of the most downstream discharge ports with a simple configuration.

  In the gas cooling method, the high-temperature gas can be a part of the cement kiln exhaust gas extracted from the kiln exhaust gas passage from the bottom of the kiln kiln to the lowermost cyclone of the preheater. The capacity of the chlorine bypass system can be enhanced while minimizing the increase in equipment cost and operation cost.

  The present invention is also a gas cooling apparatus, wherein a low-temperature gas is placed on the same plane substantially perpendicular to the flow path of the high-temperature gas and the flow direction of the high-temperature gas. A plurality of outlets for discharging into the flow, and a dividing plate that divides a region in the vicinity of the same plane where the plurality of outlets exist in the flow of the high-temperature gas into a plurality of independent flow paths. The low temperature gas is discharged from each of the plurality of discharge ports into each of the flow paths divided by the plate, thereby cooling the high temperature gas.

  According to the present invention, similarly to the above-described invention, the high-temperature gas can be efficiently cooled, and even when the gas processing system after cooling is branched in the subsequent stage, the amount of low-temperature gas is reduced for each branch system. There is no need to control, an increase in equipment cost and the like can be avoided, and pressure loss can be minimized.

  In the gas cooling device, the axial length of the flow path of the dividing plate can be configured to be 1 to 10 times the opening diameter of the discharge port. Thereby, the balance between the improvement of the cooling performance and the reduction of the pressure loss can be optimized.

  In the gas cooling apparatus, the plurality of discharge ports are arranged in a plurality of stages along the high-temperature gas flow, and the dividing plate is arranged only in the vicinity of the plurality of discharge ports on the most downstream side of the high-temperature gas. In addition, with a simple configuration, it is possible to cope with a case where a gas processing system after cooling is branched downstream of a plurality of the most downstream discharge ports.

  The gas cooling device can be arranged on the downstream side of the probe for extracting air while cooling a part of the cement kiln exhaust gas from the kiln exhaust gas passage from the bottom of the kiln kiln to the lowermost cyclone of the preheater, In the chlorine bypass system, the capacity of the chlorine bypass system can be enhanced while minimizing an increase in equipment cost and operation cost.

  As described above, according to the present invention, gas can be efficiently cooled at low cost.

It is a whole lineblock diagram showing a chlorine bypass system provided with a gas cooling device concerning the present invention. It is a figure which shows the whole secondary cooler structure shown in FIG. 1, Comprising: (a) is a schematic perspective view, (b) is an AA arrow view of (a), (c) is B of (a). FIG.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. Hereinafter, a case where the gas cooling method and apparatus according to the present invention are applied to a chlorine bypass system will be described as an example.

  FIG. 1 shows a chlorine bypass system equipped with a gas cooling device according to the present invention. This system 1 is from a kiln exhaust gas flow path from a kiln bottom of a cement kiln 2 to a lowermost cyclone (not shown) of a preheater. , A probe 3 for extracting a part of the combustion exhaust gas (reference numeral G in the figure), a cooling fan 4 for rapidly cooling the combustion exhaust gas G by supplying cold air A1 into the probe 3, and secondary cooling for further cooling the extraction gas G1 Included in the exhaust gas G3, the cyclone 7 separating the secondary cooling gas G2 into the coarse powder D1 and the exhaust gas G3 containing fine powder D2 in which the chlorine content is unevenly distributed, the cooler 8 that cools the exhaust gas G3 Filter 10 that collects the fine powder D4, the dust tank 11 that stores the fine powder D3 collected by the cooler 8 and the fine powder D4 as chlorine bypass dust D5, the exhaust fan 12, and the like. It is made. Here, the secondary cooler 5 corresponds to the gas cooling device according to the present invention.

  The probe 3, the cooling fan 4, the cyclone 7, the cooler 8, the bag filter 10, the dust tank 11, and the exhaust fan 12 are devices used in a conventional chlorine bypass system, and detailed descriptions thereof are omitted. To do.

  As shown in detail in FIG. 2, the secondary cooler 5 is connected to the outlet duct (inner cylinder outlet) of the probe 3, and has a main body 5 a having an inlet 5 b and an outlet 5 c, and an extraction gas (hot gas). Cold air (low temperature gas) A2 from the cooling fan 6 (see FIG. 1) is discharged into the flow of the extraction gas G1 on the same surface 5g (see FIG. 2C) substantially perpendicular to the flow direction of G1. And four divided plates 5e that are cross-shaped in top view and divide a region in the vicinity of the same surface 5g where the four discharge ports 5d are present into four independent flow paths. Then, cold air A2 is discharged from each of the four discharge ports 5d to each of the four divided flow paths 5f divided by the divided plate 5e to cool the extraction gas G1.

  The length L in the axial direction of the flow path of the dispersion plate 5e is set to be about four times the opening diameter D of the discharge port 5d. Thereby, the balance of the improvement of the cooling performance of the extraction gas G1 and the reduction of the pressure loss by the extraction gas G1 can be optimized.

  As shown in FIG. 1, the outlet 5c is divided into four. As the extraction gas G1 from the probe 3 increases, the secondary cooling gas G2 increases and the secondary cooling gas G2 is divided into four systems. Considering processing with a gas extraction / exhaust facility (a cyclone 7, a cooler 8 and a bag filter 10, etc., only one system is shown in FIG. 1), if there is only one system, There is no need to divide 5c.

  Next, operation | movement of the chlorine bypass system 1 which has the said structure is demonstrated, referring FIG.1 and FIG.2.

  The combustion exhaust gas G extracted by the probe 3 is cooled to about 450 to 550 ° C. by the cool air A 1 from the cooling fan 4, and the extracted gas G 1 after cooling is supplied to the secondary cooler 5.

  In the secondary cooler 5, the extracted gas G1 flowing from the inlet 5b is introduced into the four divided flow paths 5f divided by the dividing plate 5e, and each of the four discharge ports 5d is inserted into each of the divided flow paths 5f. Then, the cool air A2 is discharged, and the extracted gas G1 and the cool air A2 are mixed to cool the extracted gas G1 to about 350 ° C.

  As described above, by discharging the cold air A2 to each of the divided flow paths 5f, an appropriate amount of the cold air A2 can be mixed with the extracted gas G1 in each divided flow path 5f, and the extracted gas G1 and the cold air A2 Can be efficiently mixed, so that the cooling performance of the extraction gas G1 can be improved. Therefore, it is possible to suppress the discharge amount of the cold air A2 and to reduce heat loss. Further, since only the vicinity of the portion where the cold air A2 is discharged is divided, the pressure loss can be minimized.

  The secondary cooling gas G2 from the secondary cooler 5 is introduced into the cyclone 7 and separated into coarse powder D1 and exhaust gas G3 containing fine powder D2 in which the chlorine content is unevenly distributed. Here, since the coarse powder D1 has a low chlorine content, it can be returned to the cement raw material system.

  The exhaust gas G3 containing the fine powder D2 discharged from the cyclone 7 is supplied to the cooler 8 and indirectly cooled by the cold air A3 from the cooling fan 9, and then the fine powder D3 and D4 are cooled by the cooler 8 and the bag filter 10. Collected. Chlorine bypass dust D5 composed of the collected fine powders D3 and D4 is stored in the dust tank 11. On the other hand, since the exhaust gas G4 of the bag filter 10 contains SOx, the exhaust gas is returned to the preheater attached to the cement kiln via the exhaust fan 12 and desulfurized.

  In the above embodiment, the case where the gas cooling device is applied to the chlorine bypass system as the secondary cooler 5 has been described. However, the present invention is not limited to this as long as the high temperature gas is directly cooled by the low temperature gas. It is applicable to other uses.

  Further, the inside of the secondary cooler 5 is divided into four divided flow paths 5f. However, considering the number of facilities in consideration of the mixed cooling property of the high temperature gas and the low temperature gas, the number of the supply pipes of the low temperature gas, etc. Thru | or 3 division is preferable. However, two or more arbitrary numbers of divided flow paths 5f can be formed, and accordingly, two or more arbitrary numbers of discharge ports 5d can be provided.

For the secondary cooler 5 shown in FIG. 2 and the secondary cooler that does not divide the flow path of the high-temperature gas without providing the dividing plate 5e, the gas temperatures at the four outlets 5c are calculated using thermal fluid simulation software. When calculated, the results shown in Table 1 were obtained. Note that the extracted gas is at a temperature 1150 ° C., the amount of gas 235 nm ³ / min, cold gas at a temperature 20 ° C., were carried out at the primary cold gas amount 295Nm ³ / min, 2-order cold gas amount 420 nm ³ / min Settings .

  From the table, it can be seen that in the example, the variation in gas temperature at the four outlets 5c is smaller, and the high-temperature gas is efficiently cooled.

DESCRIPTION OF SYMBOLS 1 Chlorine bypass system 2 Cement kiln 3 Probe 4 Cooling fan 5 Secondary cooler 5a Main body 5b Inlet 5c Outlet 5d Outlet 5e Dividing plate 5f Dividing flow path 5g Same surface 6 Cooling fan 7 Cyclone 8 Cooler 9 Cooling fan 10 Bag filter 11 Dust tank 12 Exhaust fans A1 to A3 Cold air D1 Coarse powder D2 Fine powder D3, D4 Fine powder D5 Chlorine bypass dust G Part of combustion exhaust gas G1 Extraction gas G2 Secondary cooling gas G3, G4 exhaust gas

Claims (7)

A plurality of discharge ports for discharging a low temperature gas into the flow of the high temperature gas are provided on the same plane substantially perpendicular to the flow direction of the high temperature gas,
Dividing the region in the vicinity of the same surface where the plurality of discharge ports exist in the flow of the high-temperature gas into a plurality of independent flow paths;
A gas cooling method, wherein the low temperature gas is discharged from each of the plurality of discharge ports into each of the divided flow paths to cool the high temperature gas. Providing the plurality of discharge ports in a plurality of stages along the hot gas flow;
2. The gas cooling method according to claim 1, wherein only a region in the vicinity of the plurality of discharge ports on the most downstream side of the high-temperature gas is divided into a plurality of independent flow paths.   3. The gas according to claim 1, wherein the high-temperature gas is a part of the cement kiln exhaust gas extracted from the kiln exhaust gas passage from the bottom of the cement kiln to the lowermost cyclone of the preheater. Cooling method. A plurality of outlets for discharging a low-temperature gas into the flow of the high-temperature gas on the same plane substantially perpendicular to the flow direction of the high-temperature gas;
A dividing plate that divides a region in the vicinity of the same plane where the plurality of discharge ports exist in the flow of the high-temperature gas into a plurality of independent flow paths;
A gas cooling apparatus, wherein the low temperature gas is discharged from each of the plurality of discharge ports into each of the flow paths divided by the dividing plate to cool the high temperature gas.   5. The gas cooling device according to claim 4, wherein a length of the flow path in the axial direction of the dividing plate is not less than 1 and not more than 10 times an opening diameter of the discharge port. The plurality of discharge ports are arranged in a plurality of stages along the hot gas flow,
6. The gas cooling device according to claim 4, wherein the dividing plate is disposed only in the vicinity of the plurality of discharge ports on the most downstream side of the high-temperature gas.   6. The apparatus according to claim 4, wherein the probe is disposed downstream of a probe for extracting air while cooling a part of the cement kiln exhaust gas from the kiln exhaust gas flow path from the bottom of the kiln to the lowermost cyclone of the preheater. Or the gas cooling device according to 6.

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