The gas separation mechanism and the method of operating this separation mechanism.

Abstract

The invention relates to a gas-fired exhaust gas separator and a method of operating the separator capable of appropriately cooling the exhaust gas even when the exhaust rate is increased, and allowing operation while maintaining a predetermined chlorine removal efficiency. The separator (2) consists of an inner tube (21) for discharging a portion of the exhaust gas (G1) out of the furnace (1), and exhaust ports (25) which each port is made through the inner tube (21) and each port discharges cold air (C) in a direction that is perpendicular to the direction of the exhaust gas flow (G2) discharged by the inner tube (21) and is directed toward the center of the exhaust gas flow (G2).The discharge ports (25) discharge cold air (C) such that the coefficient (MC / MG) of the momentum (MC) of the cold air (C) for each discharge port (25) with the momentum (MG) of the exhaust gas (G2) satisfies a value in the range of 1.2 to 4.0, and the value (m-1 ) obtained by dividing the coefficient (VC / VG) of the wind speed (VC) of the cold air (C) with the wind speed VG of the exhaust gas (G2) by the inner diameter (D) of the inner pipe (21) satisfies a value in the range of 1.5 to 3.5.

Description

Combustion gas extraction probe and its operating method

[0001] The present invention relates to a combustion gas bleed probe and a method for operating the same.

[0002] The chlorine bypass system prevents chlorine-related coating problems in the kiln and preheater systems by extracting chlorine-containing gases from cement manufacturing facilities and discharging them outside the system. The chlorine bypass system extracts a portion of the combustion gas using a combustion gas extraction probe (hereinafter referred to as the "probe") installed near the end of the kiln, which is part of the cement manufacturing facility. The extracted combustion gas (hereinafter referred to as the "bleed gas") is mixed with low-temperature gas (hereinafter referred to as the "cold air"), and the chlorine contained in the extracted gas undergoes a phase transition from a gaseous state to a solid state. This phase transition is then recovered and removed from the system in the form of chlorine bypass dust, which is primarily composed of potassium chloride. Rapid cooling of the extracted gas concentrates the chlorine in the fine particles of the bypass dust.

[0003] In the chlorine bypass system, the raw material (coarse powder) and chlorine (fine powder) contained in the gas are separated in a cyclone, the raw material is returned to the kiln side, and the chlorine is discharged outside the system. However, if the cooling rate is slow, the amount of chlorine that returns to the kiln side along with the coarse powder with low chlorine concentration increases, and the chlorine removal efficiency decreases.

[0004] Recently, the utilization of waste materials, including waste plastics, has been promoted for the purposes of decarbonization and reducing raw material and fuel costs, resulting in an increase in the amount of chlorine (input chlorine) brought into cement manufacturing facilities. This has necessitated an increase in the capacity of the chlorine bypass system, i.e., an increase in the extraction air volume (i.e., an increase in the extraction rate). On the other hand, increasing the extraction air volume requires a corresponding increase in the amount of cold air (low-temperature gas) to cool the gas temperature below a certain level. This requires an increase in the gas velocity within the probe (to maintain gas cooling), e.g., an increase in the size of the probe. However, securing the necessary space for the probe to accommodate the increase in the size of the chlorine bypass system, including the probe, is difficult, so it is necessary to increase the gas velocity within the probe by utilizing existing facilities, for example.

[0005] The following Patent Document 1 describes cooling the bleed gas by discharging the low-temperature gas in a central direction perpendicular to the suction direction of the bleed gas and with momentum that reaches the center of the cross section.

[0006] Furthermore, Patent Document 2 listed below describes a technique for cooling the bleed gas by discharging the low-temperature gas in a central direction perpendicular to the suction direction of the bleed gas and such that the momentum vector of the low-temperature gas has a vertically downward component.

[0007] Furthermore, Patent Document 3 listed below describes a technique in which the bleed gas is cooled by discharging the low-temperature gas so that the direction of the resultant vector of the momentum of the low-temperature gas has a component in the opposite direction to the direction from the center of the cross section of the probe to the center of gravity of the velocity distribution of the bleed gas.

[0008] Furthermore, Patent Document 4 listed below describes a chlorine bypass device in which the swirling portion of the cooling pipe into which cold air is introduced is formed in a circular ring shape surrounding the air extraction pipe.

[0009] Patent No. 4744299 Patent No. 5411126 Patent No. 5290099 Patent No. 5051325

[0010] As mentioned above, if the probe is enlarged to increase the extraction rate, it becomes difficult for the low-temperature gas to reach the center of the probe, and if the gas velocity inside the probe is increased, the residence time decreases, which worsens the formation of a mixed cooling zone inside the probe and makes it difficult to achieve short-term, uniform cooling.If the extraction gas is not cooled sufficiently, the amount of chlorine that returns to the kiln side together with the coarse powder with low chlorine concentration increases, and the efficiency of chlorine removal by the chlorine bypass system decreases.

[0011] In all of Patent Documents 1 to 3, cooling is performed by discharging low-temperature gas in a direction perpendicular to the bleed gas flowing through the probe, but no operational indexes are specified regarding the discharge speed and momentum of the low-temperature gas when the bleed rate is increased.

[0012] In Patent Document 4, the cold air flows into the bleed pipe while swirling in the swirl section, stirring and mixing the bleed gas with the cold air, allowing the bleed gas to be rapidly cooled by the cold air. However, because the cold air flows in while swirling, the momentum of the cold air is lost before it mixes with the bleed gas, which may result in insufficient cooling. Furthermore, depending on the method and conditions for blowing the cold air, the cold air may leak (backflow or blow-by) at the kiln end, which may promote coating adhesion (which has a negative impact on kiln operation) or cause heat loss (which may require additional fuel burning).

[0013] Therefore, an object of the present invention is to provide a combustion gas extraction probe and an operating method thereof that can sufficiently cool the extracted gas even when the extraction rate is increased and that enables operation while maintaining a predetermined chlorine removal efficiency. Another object of the present invention is to provide a combustion gas extraction probe and an operating method thereof that can sufficiently cool the extracted gas even when the extraction rate is increased and that can suppress backflow of cold air toward the kiln end.

[0014] The combustion gas bleed probe of the present invention comprises: a gas pipe that bleeds a portion of the combustion gas from a kiln; and a plurality of discharge ports that are drilled in the gas pipe and that each discharge low-temperature gas in a direction perpendicular to the flow direction of the bleed gas bled by the gas pipe and toward the center of the flow of the bleed gas, wherein the discharge ports have a momentum ratio of the low-temperature gas per discharge port to the momentum of the bleed gas that satisfies 1.2 to 4.0, and a value (m －１ The low-temperature gas is discharged so that the ratio of the temperature difference between the temperature difference and the pressure difference satisfies 1.5 to 3.5.

[0015] The present invention also provides a method for operating a combustion gas bleed probe, which includes: a gas pipe for bleed-off a portion of the combustion gas from a kiln; and a plurality of discharge ports drilled in the gas pipe for discharging low-temperature gas in a direction perpendicular to the flow direction of the bleed gas bled by the gas pipe and toward the center of the flow of the bleed gas, wherein the ratio of the momentum of the low-temperature gas per discharge port to the momentum of the bleed gas satisfies 1.2 to 4.0, and the value (m－１ ) satisfies 1.5 to 3.5.

[0016] According to the present invention, even when the extraction rate is increased, the extracted gas can be sufficiently cooled and operation can be performed while maintaining a predetermined chlorine removal efficiency.

[0017] The combustion gas extraction probe of the present invention comprises a gas pipe that extracts a portion of the combustion gas from a kiln, and a plurality of discharge ports drilled in the gas pipe and each discharge a low-temperature gas into the extracted gas extracted by the gas pipe, and the plurality of discharge ports are arranged so that the low-temperature gases discharged from each of the discharge ports do not collide with each other within the gas pipe.

[0018] Furthermore, a method for operating a combustion gas bleed probe of the present invention is a method for operating the above-mentioned combustion gas bleed probe, wherein the wind speed of the low-temperature gas discharged from the discharge port satisfies 25 to 180 m / s, and the ratio of the momentum of the low-temperature gas per discharge port to the momentum of the bleed gas satisfies 1.8 to 5.3.

[0019] According to the present invention, even when the extraction rate is increased, the extracted gas can be sufficiently cooled and the backflow of cold air toward the bottom of the oven can be suppressed.

[0020] FIG. 1 is an overall configuration diagram showing a first embodiment of a chlorine bypass system including a combustion gas bleed probe according to the present invention; FIG. 2 is a cross-sectional view schematically showing the probe; FIG. 3 is a cross-sectional view showing the "side" arrangement of the discharge port in analysis 2; FIG. 4 is a cross-sectional view showing the "down" arrangement of the discharge port in analysis 2; FIG. 5 is a cross-sectional view showing the "Y" arrangement of the discharge port in analysis 2; FIG. 6 is a cross-sectional view showing the "inverted Y" arrangement of the discharge port in analysis 2;

[0021] [First embodiment] A first embodiment of a combustion gas bleeding probe and an operating method thereof according to the present invention will be described below with reference to Figures 1 to 3. Note that in each figure, the dimensional ratios in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0022] 1 is a schematic diagram showing the overall configuration of a first embodiment of a chlorine bypass system including a combustion gas extraction probe according to the present invention. The chlorine bypass system 100 includes a probe 2 for extracting a portion of the combustion gas G1 from the kiln exhaust gas flow path from the kiln end 1a to the lowest cyclone (not shown), a cold air fan 3 for supplying cold air C (corresponding to low-temperature gas) to the probe 2, an inverter 4 for adjusting the output of the cold air fan 3, a cyclone 5 as a classifier for separating coarse particles A1 contained in a mixed gas G3 obtained by mixing the extracted gas G2 and the cold air C, a cooler 6 for cooling the mixed gas G4 containing fine particles A2 discharged from the cyclone 5, a dust collector 7 for recovering fine particles A2 from the exhaust gas G5 discharged from the cooler 6, an exhaust fan 8 for attracting the exhaust gas G6 from the dust collector 7, and a measuring instrument 9 (an anemometer, a thermometer, etc.) for measuring the wind speed of the exhaust fan 8.

[0023] 2 is a cross-sectional view showing a schematic diagram of the probe 2. The probe 2 protrudes from the kiln end 1a to a rising portion 1b extending upward as part of the kiln exhaust gas flow path. An inlet 2a of the probe 2 opens into the kiln exhaust gas flow path in the rising portion 1b. The extraction rate of the probe 2 is 5% or more, and preferably 10 to 15%. The extraction rate refers to the ratio (proportion) of the gas volume (Nm3 / unit time) of the extracted gas G2 extracted per unit time to the gas volume (Nm3 / unit time) of the combustion gas G1 passing through the kiln end 1a per unit time.

[0024] The amount of extracted gas G2 is preferably 2,500 Nm3 / h or more, and more preferably 10,000 Nm3 / h or more.

[0025] The probe 2 includes a cylindrical inner pipe 21 (corresponding to a gas pipe), a cylindrical outer pipe 22 surrounding the inner pipe 21, a cold air passage 23 formed between the inner pipe 21 and the outer pipe 22, and a supply port 24 for supplying cold air from the cold air fan 3 to the cold air passage 23. The bleed gas G2 flows in the inner pipe 21 in the direction of the arrow.

[0026] The probe 2 is provided with a plurality of discharge ports 25 formed in the inner pipe 21 and discharging the cold air C supplied to the cold air passage 23 toward the extracted gas G2. The discharge ports 25 are formed in a circular shape.

[0027] 3 is a view taken along the line III-III in FIG. 2. The multiple discharge ports 25 are arranged at approximately the same position in the extension direction of the inner pipe 21, and preferably at the same position. In other words, the multiple discharge ports 25 are preferably arranged in a plane perpendicular to the extension direction of the inner pipe 21. The multiple discharge ports 25 each discharge cold air C in a direction perpendicular to the flow direction of the bleed gas G2 inside the inner pipe 21. However, as will be described later, the multiple discharge ports 25 do not need to be arranged at exactly the same position in the extension direction of the inner pipe 21, as long as the cold air C discharged from each discharge port 25 can collide with each other and be diffused.

[0028] In this embodiment, the two discharge ports 25 are provided at positions that are symmetrical with respect to a vertical line P that passes through the center O of the inner pipe 21. The two discharge ports 25 are arranged on the left and right so that the angle between a line L connecting the center 25c of each discharge port 25 and the center O of the inner pipe 21 and a horizontal line H that passes through the center O of the inner pipe 21 is 15°. The two discharge ports 25 each discharge cold air C toward the center O of the inner pipe 21. In other words, the two discharge ports 25 each discharge cold air C toward the center of the flow of the bleed gas G2 in the inner pipe 21. Therefore, the cold air C discharged from the two discharge ports 25 collide with each other near the center O of the inner pipe 21 and diffuses. This enables the cold air C and the bleed gas G2 to be sufficiently mixed.

[0029] On the other hand, the cold air C after collision also has a velocity vector in the opposite direction to the flow direction of the extracted gas G2, i.e., in the direction toward the kiln end 1a. If the volume of cold air C toward the kiln end 1a becomes excessive, a backflow of cold air C toward the kiln end 1a occurs, which can cause heat loss.

[0030] The chlorine bypass system 100 includes a control unit (not shown). The control unit can grasp the volume and momentum of the extracted gas G2 in real time from the exhaust air volume calculated from the measurement value of the measuring instrument 9 and the volume of cold air discharged from the cold air fan 3, and can control the inverter 4 to always operate the cold air fan 3 at an optimum output.

[0031] In this specification, the momentum of gas (per unit time) is defined as follows: Momentum of gas [kg m / s2 ] = Density [kg / m 3 ] × Wind speed [m / s] × Air volume [m 3 / s]

[0032] The control unit controls the flow rate of the extracted gas G2 so that the ratio (MC / MG) of the momentum MC of the extracted gas C calculated from the velocity, volume, and temperature of the extracted gas C per discharge port 25 to the momentum MG of the extracted gas G2 calculated from the velocity, volume, and temperature of the extracted gas G2 at the inlet 2a of the probe 2 is in the range of 1.2 to 4.0, and the ratio (VC / VG) of the velocity VC of the extracted gas C to the velocity VG of the extracted gas G2 divided by the probe diameter D [m －１ The output of the cooling fan 3 is adjusted so that the ratio of the extracted gas G2 to the total extracted gas G2 is in the range of 1.5 to 3.5. This makes it possible to sufficiently cool the extracted gas G2 even when the extraction rate is increased, and to operate the system while maintaining a predetermined chlorine removal efficiency (see Example 1 below for details).

[0033] If the momentum ratio (MC / MG) is reduced too much, the momentum MC of the cold air C is smaller than the momentum MG of the bleed gas G2, making it difficult to sufficiently mix the cold air C with the bleed gas G2. Therefore, the momentum ratio (MC / MG) is set to 1.2 or more, and preferably 3.0 or more.

[0034] On the other hand, if the momentum ratio (MC / MG) is increased too much, pressure loss increases, and it becomes necessary to increase the size of the cold air fan 3. Also, as the momentum ratio (MC / MG) increases, the reduction rate of the temperature deviation at the outlet cross section 2b of the probe 2 (details will be described later) decreases, but the amount of cold air that flows back through the probe 2 and reaches the kiln bottom 1a increases. Therefore, the momentum ratio (MC / MG) is 4.0 or less, and preferably 3.6 or less.

[0035] If the ratio of wind speeds to the probe diameter (VC / VG / D) is reduced too much, the cold air C will be swept toward the cyclone 5 by the extracted gas G2 before colliding and diffusing, making it difficult to achieve sufficient mixing. Therefore, the ratio of wind speeds to the probe diameter (VC / VG / D) is preferably 1.5 or more, and more preferably 2.3 or more.

[0036] If the ratio of air velocity to probe diameter (VC / VG / D) is too high, the pressure loss increases, and it becomes necessary to increase the size of the cold air fan 3. In addition, the amount of cold air that flows back through the probe 2 and reaches the kiln bottom 1a increases. Therefore, the ratio of air velocity to probe diameter (VC / VG / D) is preferably 3.5 or less, and more preferably 3.0 or less.

[0037] The wind speed VC of the cold air C is preferably 25 to 180 m / s, more preferably 50 to 150 m / s.

[0038] In addition, a variable nozzle (not shown) that changes the opening area of ​​the outlet 25 may be provided, and the momentum ratio (MC / MG) may be increased by increasing only the wind speed VC while maintaining the air volume of the cold air C.

[0039] Specific examples will be given below to explain the present invention in more detail, but the present invention is not limited to these examples.

[0040] The inventors conducted a simulation analysis of the mixed state of the bleed gas G2 and the cold air C to search for factors that contribute to improving the cooling efficiency of the bleed gas G2. The software used for the simulation analysis was Fluent 2020 R2 manufactured by ANSYS. The extraction rate in the chlorine bypass system 100 was set to 5 to 15%. The cold air C was 20°C, and was introduced so that the average temperature at the outlet cross section 2b of the probe 2 (see Figure 2) was 400°C. Under each condition, the speed of the cold air C was changed while maintaining a predetermined air volume by adjusting the area of ​​the discharge port 25.

[0041] (Analysis 1) The temperature distribution inside the probe 2 was evaluated by changing the extraction rate, the velocity of the cold air C (shown as "cold air velocity" in Table 1), and the probe diameter D. The shapes of the probe 2 used in the simulation analysis are shown in Figures 2 and 3. The analysis conditions are shown in Table 1. The extraction rate was set to 5 to 15%, and the cold air velocity was set to 28 to 200 m / s. The size of the probe 2 was set based on the momentum ratio (MC / MG) of the cold air C to the bleed gas G2, and other factors. Analysis Examples 1-1 to 3-2 were Type A, Analysis Examples 4-1 to 4-4 were enlarged to a cross-sectional area 1.5 times that of Type A, and Analysis Examples 5-1 to 5-2 were reduced to a cross-sectional area 0.5 times that of Type A. In Table 1, "cold air-to-bleed gas momentum ratio" means the ratio (MC / MG) of the momentum MC of the cold air C per discharge port 25 to the momentum MG of the bleed gas G2, and "cold air-to-bleed gas wind speed ratio / probe diameter" means the ratio (VC / VG / D) of the wind speed VC of the cold air C to the wind speed VG of the bleed gas G2 (the same applies to Tables 2 to 4 described later).

[0042] (Analysis 2) In the above-described Type A probe 2, the arrangement and number of outlets 25 were changed. The analysis conditions are shown in Table 2, and the arrangements of the outlets 25 are shown in Figures 4A to 4D. In Table 2, "horizontal" indicates that the outlets 25 are arranged as shown in Figure 4A, "bottom" indicates that the outlets 25 are arranged as shown in Figure 4B, "Y" indicates that the outlets 25 are arranged as shown in Figure 4C, and "reverse Y" indicates that the outlets 25 are arranged as shown in Figure 4D (the same applies to Table 4 described below).

[0043]

[0044]

[0045] From the viewpoint of introducing cold air C so that the average temperature at the outlet cross section 2b of the probe 2 becomes 400°C and lowering the temperature of the extracted gas G2 to 600 to 700°C or less, which is the melting point of chlorine compounds (see Japanese Patent No. 4294871), the degree of gas cooling is judged based on whether or not a temperature deviation of 200°C or less at the outlet cross section 2b of the probe 2 can be achieved. Here, the temperature deviation at the outlet cross section 2b of the probe 2 refers to the variation from the average temperature within the outlet cross section 2b.

[0046] An increase in the velocity of the cold air C raises concerns about the possibility of cold air C being mixed into the kiln end 1a (backflow). Therefore, to quantify the amount of cold air reaching the kiln end 1a relative to the total cold air volume, the backflow rate of the introduced cold air C was calculated from the temperature drop (difference from the temperature of the kiln end 1a) at the junction (inlet 2a) between the probe 2 and the kiln end 1a. This backflow rate can be considered an indicator of the force with which the discharged cold air C collides and diffuses; a high value indicates a strong mixing force of the cold air C within the probe 2. In fluid simulations, almost all of the cold air C reaching the kiln end 1a flows back toward the probe 2. However, if the amount is excessive, the cold air C may blow through to the kiln end 1a, resulting in heat loss. Therefore, it is desirable to minimize the backflow rate; in this analysis, it was set to 10% or less.

[0047] The temperature deviation and backflow rate at the outlet cross section 2b of the probe 2 in analysis 1 are shown in Table 3. In Table 3, "◯" indicates that the temperature deviation at the outlet cross section 2b of the probe 2 is 200°C or less and the backflow rate is 10% or less, and "×" indicates that the temperature deviation at the outlet cross section 2b of the probe 2 exceeds 200°C or the backflow rate exceeds 10%.

[0048]

[0049] As the cold air-to-bleed gas momentum ratio increased, the temperature deviation decreased, and even when the extraction rate was 15% and the probe diameter was different, the temperature deviation tended to decrease.

[0050] Figure 5 shows the relationship between the cold air-to-bleed gas momentum ratio and the temperature deviation at the outlet cross section 2b of the probe 2 in analysis 1. The open areas represent conditions judged as "x", and the solid areas represent conditions judged as "o" (the same applies to Figure 6). A correlation was confirmed between the cold air-to-bleed gas momentum ratio and the temperature deviation at the outlet cross section 2b of the probe 2, regardless of the extraction rate or the probe diameter D. However, the operating conditions cannot be determined solely by the cold air-to-bleed gas momentum ratio.

[0051] Therefore, the inventors carried out a judgment using an index including factors of wind speed and probe diameter D as factors related to the collision of cold air C in addition to the cold air-to-bleed gas momentum ratio. The results are shown in Figure 6. As shown in Figure 6, when the cold air-to-bleed gas momentum ratio is 1.2 to 4.0 and the cold air-to-bleed gas wind speed ratio / probe diameter (m －１ ) is in the range of 1.5 to 3.5, the temperature deviation at the outlet cross section 2b of the probe 2 is 200°C or less, regardless of the extraction rate and the probe diameter D. Therefore, by using this index, sufficient cooling performance of the chlorine bypass system can be easily achieved even for different chlorine bypass systems.

[0052] The temperature deviation at the exit cross section 2b of the probe 2 in analysis 2 is shown in Table 4. In Table 4, "◯" indicates that the backflow rate is 10% or less, and "×" indicates that the backflow rate is more than 10%.

[0053]

[0054] Regardless of the arrangement of the discharge ports 25, the temperature deviation at the outlet cross section 2b of the probe 2 tended to decrease as the cold air-to-bleed gas momentum ratio increased. Therefore, a predetermined cooling performance can be achieved by controlling the cold air-to-bleed gas momentum ratio regardless of the arrangement of the discharge ports 25. Note that the highest cooling performance is achieved when the discharge ports 25 are arranged "horizontally." That is, it is preferable that the multiple discharge ports 25 include a pair of discharge ports 25 arranged opposite each other on both horizontal sides of the inner pipe 21 and discharging cold air C in the horizontal direction. This is because, when cold air C discharged horizontally from a pair of discharge ports 25 arranged opposite each other on both horizontal sides collide head-on, the cold air C is less likely to drift vertically, resulting in high cooling performance.

[0055] As described above, the probe 2 according to this embodiment comprises the inner pipe 21 for extracting a portion of the combustion gas G1 from the kiln 1, and a plurality of discharge ports 25 drilled in the inner pipe 21, each of which discharges cold air C in a direction perpendicular to the flow direction of the extracted gas G2 extracted by the inner pipe 21 and in the direction of the center of the flow of the extracted gas G2. The discharge ports 25 have a ratio (MC / MG) of the momentum MC of the cold air C per port 25 to the momentum MG of the extracted gas G2 that satisfies 1.2 to 4.0, and a value (m －１ ) is 1.5 to 3.5.

[0056] According to this configuration, even when the extraction rate increases, the extracted gas G2 can be sufficiently cooled, and operation can be performed while maintaining a predetermined chlorine removal efficiency.

[0057] In addition, in the probe 2 according to this embodiment, the plurality of outlets 25 preferably include a pair of outlets 25 arranged opposite each other on both horizontal sides of the inner tube 21 and discharging the cold air C in the horizontal direction.

[0058] This configuration makes it possible to achieve good cooling performance.

[0059] In the probe 2 according to this embodiment, the wind speed VC of the cold air C is preferably 25 to 180 m / s.

[0060] This configuration makes it possible to achieve good cooling performance.

[0061] Furthermore, in the probe 2 according to this embodiment, the cold air C discharged from each of the multiple outlets 25 has a velocity vector in the opposite direction to the flow direction of the extracted gas G2 after colliding with each other, and it is preferable that the ratio of the cold air C flowing back to the kiln bottom 1a to the discharged cold air C is 10% or less.

[0062] This configuration makes it possible to keep the backflow rate low and suppress heat loss.

[0063] Furthermore, the method of operating the probe 2 according to this embodiment is a method of operating the probe 2, which is provided with an inner pipe 21 that extracts a portion of the combustion gas G1 from the kiln 1, and a plurality of discharge ports 25 that are drilled in the inner pipe 21 and that each discharge cold air C in a direction perpendicular to the flow direction of the extracted gas G2 extracted by the inner pipe 21 and toward the center of the flow of the extracted gas G2, wherein the ratio (MC / MG) of the momentum MC of the cold air C per discharge port 25 to the momentum MG of the extracted gas G2 satisfies 1.2 to 4.0, and the value (m －１ ) satisfies 1.5 to 3.5.

[0064] According to this configuration, even when the extraction rate increases, the extracted gas G2 can be sufficiently cooled, and operation can be performed while maintaining a predetermined chlorine removal efficiency.

[0065] The combustion gas bleed probe and its operating method are not limited to the configurations of the above-described embodiments, and are not limited to the above-described functions and effects. Furthermore, it goes without saying that various modifications can be made to the combustion gas bleed probe without departing from the spirit of the present invention. For example, the configurations and methods of the above-described embodiments may be arbitrarily adopted and combined, and further, it goes without saying that one or more of the configurations and methods of the various modified examples described below may be arbitrarily selected and adopted in the configurations and methods of the above-described embodiments.

[0066] In the probe 2 according to the above embodiment, two outlets 25 are formed in the inner tube 21. However, the probe 2 is not limited to this configuration. For example, as shown in Fig. 4A, three or more outlets 25 may be formed in the inner tube 21. When three or more outlets 25 are provided, they are preferably arranged at equal intervals in the circumferential direction of the inner tube 21.

[0067] Second Embodiment A combustion gas bleeding probe and an operating method thereof according to a second embodiment of the present invention will now be described with reference to Figures 7 to 9. Note that in each figure, the dimensional ratios shown in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

[0068] 7 is a schematic diagram showing the overall configuration of a second embodiment of a chlorine bypass system including a combustion gas extraction probe according to the present invention. The chlorine bypass system 100 includes a probe 2 for extracting a portion of the combustion gas G1 from the kiln exhaust gas flow path from the kiln end 1a to the lowest cyclone (not shown), a cold air fan 3 for supplying cold air C (corresponding to low-temperature gas) to the probe 2, a cyclone 5 as a classifier for separating coarse particles A1 contained in a mixed gas G3 obtained by mixing the extracted gas G2 and the cold air C, a cooler 6 for cooling the mixed gas G4 containing fine particles A2 discharged from the cyclone 5, a dust collector 7 for recovering the fine particles A2 from the exhaust gas G5 discharged from the cooler 6, and an exhaust fan 8 for drawing the exhaust gas G6 from the dust collector 7.

[0069] 8 is a cross-sectional view showing a schematic diagram of the probe 2. The probe 2 protrudes from the kiln end 1a to the rising portion 1b extending upward as part of the kiln exhaust gas flow path. The inlet 2a of the probe 2 opens into the kiln exhaust gas flow path in the rising portion 1b. The extraction rate by the probe 2 is 10% or more, preferably 12% or more, and more preferably 15% or more. The extraction rate refers to the ratio (proportion) of the gas volume (Nm3 / unit time) of the extracted gas G2 extracted per unit time to the gas volume (Nm3 / unit time) of the combustion gas G1 passing through the kiln end 1a per unit time.

[0070] The amount of extracted gas G2 is preferably 2,500 Nm3 / h or more, and more preferably 10,000 Nm3 / h or more.

[0071] The probe 2 includes a cylindrical inner pipe 21 (corresponding to a gas pipe), a cylindrical outer pipe 22 surrounding the inner pipe 21, a cold air passage 23 formed between the inner pipe 21 and the outer pipe 22, and a supply port 24 for supplying cold air from the cold air fan 3 to the cold air passage 23. The bleed gas G2 flows in the inner pipe 21 in the direction of the arrow.

[0072] The probe 2 is provided with a plurality of discharge ports 250 formed in the inner pipe 21 and discharging the cold air C supplied to the cold air passage 23 toward the extracted gas G2. Each discharge port 250 is formed in a circular shape.

[0073] Figure 9 is a view taken along the line IX-IX in Figure 8. The multiple outlets 250 are arranged at approximately the same position in the extension direction of the inner tube 21, and preferably at the same position. In other words, the multiple outlets 250 are preferably arranged in a plane perpendicular to the extension direction of the inner tube 21. However, the multiple outlets 250 do not need to be arranged at exactly the same position in the extension direction of the inner tube 21.

[0074] In this embodiment, the two discharge ports 250 are arranged symmetrically with respect to the center O of the inner tube 21. The two discharge ports 250 are arranged 180 degrees apart from each other in the circumferential direction of the inner tube 21.

[0075] The outlets 250 are arranged so that their centers 250c are parallel to the horizontal line H. The two outlets 250 each discharge cold air C into the extracted gas G2 in the inner pipe 21. That is, the two outlets 250 are arranged alternately, and the cold air C discharged from each outlet 250 does not collide with each other within the inner pipe 21. As a result, the cold air C discharged from each outlet 250 does not collide with each other and diffuse, and is less likely to flow toward the kiln end 1a. As a result, backflow of cold air C toward the kiln end 1a is suppressed, thereby suppressing heat loss.

[0076] The inner tube 21 preferably has a nozzle 260 surrounding the outlet 250. The cylindrical nozzle 260 is arranged coaxially with the center 250c of the outlet 250. By providing the nozzle 260 around the outlet 250, the cold air C is discharged in a direction along the center 250c of the outlet 250. Note that if the wall thickness of the inner tube 21 is sufficiently large, the nozzle 260 is not necessarily required.

[0077] The chlorine bypass system 100 includes a control unit (not shown). The control unit can adjust the output of the cold air fan 3.

[0078] The control unit adjusts the output of the cold air fan 3 so that the ratio (MC / MG) of the momentum MC of the cold air C calculated from the wind speed, air volume, and temperature of the cold air C per outlet 250 to the momentum MG of the extracted gas G2 calculated from the wind speed, air volume, and temperature of the extracted gas G2 at the inlet 2a of the probe 2 is in the range of 1.8 to 5.3. This makes it possible to sufficiently cool the extracted gas G2 even when the extraction rate increases, and enables operation while maintaining a predetermined chlorine removal efficiency (see Example 2 described below for details).

[0079] In this specification, the momentum of gas (per unit time) is defined as follows: Momentum of gas [kg m / s 2 ] = Density [kg / m 3 ] × Wind speed [m / s] × Air volume [m 3 / s]

[0080] If the momentum ratio (MC / MG) is reduced too much, the momentum MC of the cold air C becomes smaller than the momentum MG of the bleed gas G2, making it difficult to sufficiently mix the cold air C with the bleed gas G2. Therefore, the momentum ratio (MC / MG) is set to 1.8 or more, and preferably 3.0 or more.

[0081] On the other hand, if the momentum ratio (MC / MG) is increased too much, pressure loss increases, and it becomes necessary to increase the size of the cold air fan 3. Also, as the momentum ratio (MC / MG) increases, the reduction rate of the temperature deviation at the outlet cross section 2b of the probe 2 (details will be described later) decreases, but the amount of cold air that flows back through the probe 2 and reaches the kiln bottom 1a increases. Therefore, the momentum ratio (MC / MG) is 5.3 or less, and preferably 4.0 or less.

[0082] The wind speed of the cold air C is preferably 25 to 180 m / s, more preferably 50 to 150 m / s.

[0083] In addition, a variable nozzle (not shown) that changes the opening area of ​​the outlet 250 may be provided, and the momentum ratio (MC / MG) may be increased by increasing only the wind speed while maintaining the air volume of the cold air C.

[0084] Specific examples will be given below to explain the present invention in more detail, but the present invention is not limited to these examples.

[0085] The inventors confirmed the effect of arranging the plurality of discharge ports 250 through a simulation analysis of the mixed state of the bleed gas G2 and the cold air C. The software used for the simulation analysis was Fluent 2020 R2 manufactured by ANSYS.

[0086] The cross-sectional shapes of the probe used in the simulation analysis are shown in Figures 10A and 10B (note that the outer pipe 22 is not shown). Figure 10A shows an example in which a pair of outlets 250 are arranged so that each of the cold air streams C is discharged in a direction perpendicular to the flow direction of the extracted gas G2 from the inner pipe 21 and so that the discharged cold air streams C do not collide with each other inside the inner pipe 21. Figure 10B shows an example in which a pair of outlets 250A are arranged so that each of the cold air streams C is discharged in a direction perpendicular to the flow direction of the extracted gas G2 from the inner pipe 21 and toward the center of the flow of the extracted gas G2.

[0087] The analysis conditions are shown in Table 5. The extraction rate in the chlorine bypass system 100 was set to 10 to 15%. The cold air C was 20°C, and was introduced so that the average temperature at the outlet cross section 2b of the probe 2 (see Figure 2) was 400°C. Under each condition, the speed of the cold air C was changed while maintaining a predetermined air volume by adjusting the area of ​​the outlets 250 and 250A.

[0088] The wind speed of the cold air C was set and analyzed taking into consideration the ratio of the momentum of the extracted gas G2 calculated from the wind speed, air volume, and temperature of the extracted gas G2 at the inlet 2a of the probe 2 to the momentum of the cold air C calculated from the wind speed, air volume, and temperature of the cold air C per outlet 250, 250A.

[0089] In Table 5, "cool air speed" means the wind speed of the cool air C, and "cool air-bleed gas momentum ratio" means the ratio (MC / MG) of the momentum MC of the cool air C per outlet 250, 250A to the momentum MG of the bleed gas G2 (the same applies to Table 6 described later). Also, in Table 5, "staggered type" means that the outlets are arranged as shown in Fig. 10A, and "collision type" means that the outlets are arranged as shown in Fig. 10B.

[0090]

[0091] From the viewpoint of introducing cold air C so that the average temperature at the outlet cross section 2b of the probe 2 becomes 400°C and lowering the temperature of the extracted gas G2 to 600 to 700°C or less, which is the melting point of chlorine compounds (see Japanese Patent No. 4294871), the degree of gas cooling is judged based on whether or not a temperature deviation of 200°C or less at the outlet cross section 2b of the probe 2 can be achieved. Here, the temperature deviation at the outlet cross section 2b of the probe 2 refers to the variation from the average temperature within the outlet cross section 2b.

[0092] In addition, the proportion of cold air C that reached the inlet 2a of the probe 2 was calculated from the temperature drop (difference from the temperature of the kiln end 1a) at the joint (inlet 2a) between the probe 2 and the kiln end 1a, and evaluated as the backflow rate of the introduced cold air C. The temperature deviation at the outlet cross section 2b of the probe 2 and the backflow rate to the kiln end 1a are shown in Table 6. In Table 6, "○" indicates a backflow rate of 0, "△" indicates a backflow rate of 10% or less, and "×" indicates a backflow rate of more than 10%.

[0093]

[0094] In the "staggered type" of analysis examples 6-1 to 7-2, the temperature deviation is slightly higher than that of the "collision type" of analysis examples 8-1 to 9-2 under the same conditions, but the temperature deviation is below 200°C, and sufficient cooling is achieved.

[0095] In addition, in the "staggered type" of analysis examples 6-1 to 7-2, no backflow occurs toward the kiln end 1a. This is because, in the "collision type," the cold air C discharged from each of the multiple outlets 250A collides with each other and then generates a velocity vector toward the kiln end 1a, whereas in the "staggered type," there is no direct collision between the cold air C, so the amount of velocity vector generated toward the kiln end 1a is small.

[0096] Fig. 11 shows the relationship between the cold air-to-bleed gas momentum ratio and the temperature deviation at the outlet cross section 2b of the probe 2. As shown in Fig. 11, when the cold air-to-bleed gas momentum ratio is in the range of 1.8 to 5.3, the temperature of the bleed gas G2 in the probe 2 can be uniformed more quickly when it is in the range of 3.0 to 4.0.

[0097] As described above, the probe 2 according to this embodiment comprises an inner pipe 21 that extracts a portion of the combustion gas G1 from the kiln 1, and a plurality of discharge ports 250 drilled in the inner pipe 21 and each discharging cold air C into the extracted gas G2 extracted by the inner pipe 21, and the plurality of discharge ports 250 are arranged so that the cold air C discharged from each discharge port 250 does not collide with each other within the inner pipe 21.

[0098] With this configuration, the cold air C discharged from each outlet 250 does not collide with each other and diffuse, and is less likely to flow toward the kiln end 1a. This allows the extracted gas G2 to be sufficiently cooled even when the extraction rate is increased, and also prevents the cold air C from flowing back toward the kiln end 1a.

[0099] In the probe 2 according to this embodiment, the plurality of outlets 250 are preferably arranged at the same position in the extension direction of the inner tube 21 .

[0100] This configuration makes it possible to achieve good cooling performance.

[0101] Furthermore, in the probe 2 according to this embodiment, it is preferable that the multiple outlets 250 are arranged point-symmetrically with respect to the center O of the inner tube 21 when viewed in the extension direction of the inner tube 21.

[0102] This configuration makes it possible to achieve good cooling performance.

[0103] In the probe 2 according to this embodiment, the plurality of outlets 250 are preferably arranged at equal intervals in the circumferential direction of the inner tube 21 .

[0104] This configuration makes it possible to achieve good cooling performance.

[0105] In addition, in the operating method of the probe 2 according to this embodiment, the wind speed of the cold air C discharged from the outlet 250 satisfies 25 to 180 m / s, and the ratio (MC / MG) of the momentum MC of the cold air C per outlet 250 to the momentum MG of the extracted gas G2 satisfies 1.8 to 5.3.

[0106] According to this configuration, even when the extraction rate is increased, the extracted gas G2 can be sufficiently cooled, and the backflow of the cold air C to the kiln bottom 1a can be suppressed.

[0107] Furthermore, in the operating method of the probe 2 according to this embodiment, it is preferable that the cold air C does not flow back to the kiln bottom 1a after colliding with the inner wall surface of the inner tube 21.

[0108] This configuration allows the backflow rate to be kept low.

[0109] The combustion gas bleed probe and its operating method are not limited to the configurations of the above-described embodiments, and are not limited to the above-described functions and effects. Furthermore, it goes without saying that various modifications can be made to the combustion gas bleed probe without departing from the spirit of the present invention. For example, the configurations and methods of the above-described embodiments may be arbitrarily adopted and combined, and further, it goes without saying that one or more of the configurations and methods of the various modified examples described below may be arbitrarily selected and adopted in the configurations and methods of the above-described embodiments.

[0110] (1) In the probe 2 according to the above embodiment, the multiple outlets 250 are arranged at the same position in the extension direction of the inner tube 21. However, the probe 2 is not limited to this configuration. For example, the multiple outlets 250 may be arranged at different positions in the extension direction of the inner tube 21.

[0111] (2) In the probe 2 according to this embodiment, the multiple outlets 250 are arranged in point symmetry with respect to the center O of the inner tube 21 when viewed in the extension direction of the inner tube 21. However, the probe 2 is not limited to this configuration. For example, as shown in Figures 12A and 12B, the multiple outlets 250 do not have to be arranged in point symmetry with respect to the center O of the inner tube 21 when viewed in the extension direction of the inner tube 21.

[0112] (3) In the probe 2 according to this embodiment, the two outlets 250 are arranged at equal intervals in the circumferential direction of the inner tube 21. However, the probe 2 is not limited to this configuration. For example, as shown in Fig. 12C, three outlets 250 may be arranged at equal intervals in the circumferential direction of the inner tube 21.

[0113] DESCRIPTION OF SYMBOLS 1: Kiln 1a: Kiln bottom 1b: Rising portion 2: Probe 2a: Probe inlet 2b: Probe outlet cross section 3: Cold air fan 4: Inverter 5: Cyclone 6: Cooler 7: Dust collector 8: Exhaust fan 9: Measuring instrument 21: Inner pipe 22: Outer pipe 23: Cold air passage 24: Supply port 25: Discharge port 25c: Discharge port center 250: Discharge port 250c: Discharge port center 260: Nozzle 100: Chlorine bypass system A1: Coarse powder A2: Fine powder C: Cold air D: Probe diameter G1: Combustion gas G2: Extracted gas G3: Mixed gas G4: Mixed gas G5: Exhaust gas G6: Exhaust gas H: Horizontal line MC : Momentum of cold air MG : Momentum of bleed gas O : Center of inner pipe VC : Wind speed of cold air VG : Wind speed of bleed gas

Claims

1. A gas pipe that extracts a portion of the combustion gas from a kiln, and a plurality of discharge ports drilled into the gas pipe that each discharge low-temperature gas perpendicular to the flow direction of the extracted gas extracted by the gas pipe and toward the center of the flow of the extracted gas, wherein the discharge ports have a momentum ratio of the low-temperature gas per discharge port to the momentum of the extracted gas that satisfies 1.2 to 4.0, and the ratio of the wind speed of the low-temperature gas to the wind speed of the extracted gas divided by the inner diameter of the gas pipe (m －１ ) is 1.5 to 3.

5.

2. The combustion gas extraction probe according to claim 1, characterized in that the plurality of discharge ports include a pair of discharge ports arranged opposite each other on both horizontal sides of the gas pipe and discharging the low-temperature gas in the horizontal direction.

3. The combustion gas extraction probe according to claim 1, wherein the low-temperature gas has a wind speed of 25 to 180 m / s.

4. The combustion gas extraction probe described in claim 1, characterized in that the low-temperature gases discharged from each of the multiple outlets have a velocity vector in the opposite direction to the flow direction of the extracted gas after colliding with each other, and the ratio of the low-temperature gas flowing back to the kiln end to the discharged low-temperature gas is 10% or less.

5. A method for operating a combustion gas extraction probe comprising: a gas pipe that extracts a portion of the combustion gas from a kiln; and a plurality of outlets drilled into the gas pipe, each of which discharges low-temperature gas in a direction perpendicular to the flow direction of the extracted gas extracted by the gas pipe and toward the center of the flow of the extracted gas, wherein the ratio of the momentum of the low-temperature gas per outlet to the momentum of the extracted gas satisfies 1.2 to 4.0, and the value (m －１ ) satisfies 1.5 to 3.

5.

6. A combustion gas extraction probe comprising: a gas pipe that extracts a portion of the combustion gas from a kiln; and a plurality of discharge ports drilled in the gas pipe, each of which discharges low-temperature gas into the extracted gas extracted by the gas pipe, wherein the plurality of discharge ports are arranged so that the low-temperature gases discharged from each of the discharge ports do not collide with each other within the gas pipe.

7. The combustion gas extraction probe according to claim 6, wherein the plurality of discharge ports are arranged at the same position in the extending direction of the gas pipe.

8. A combustion gas extraction probe as described in claim 6, characterized in that the multiple discharge ports are arranged symmetrically with respect to the center of the gas pipe when viewed in the extension direction of the gas pipe.

9. A combustion gas extraction probe according to claim 6, wherein the plurality of discharge ports are arranged at equal intervals in the circumferential direction of the gas pipe.

10. A method for operating a combustion gas bleed probe as set forth in any one of claims 6 to 9, characterized in that the wind speed of the low-temperature gas discharged from the discharge ports is 25 to 180 m / s, and the ratio of the momentum of the low-temperature gas per discharge port to the momentum of the bleed gas is 1.8 to 5.

3.

11. A method for operating a combustion gas extraction probe as described in claim 10, characterized in that the low-temperature gas does not flow back to the kiln bottom after colliding with the inner wall surface of the gas pipe.

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