Patent Application
20240085016
The present invention relates to a cement kiln burner and a method for operating the same.
In cement production facilities, combustible wastes have been used as substitutes for fuels and raw materials in a rotary kiln (hereinafter referred to as “cement kiln”) used for calcining cement clinkers. In recent years, for further use of the combustible wastes, use of combustible wastes having poorer combustibility than before is also increasing. In addition, in order to reduce the cost of coal that has been conventionally used as main fuel, use of coal having poorer combustibility than before is also increasing. Therefore, there is a demand for a technique for simultaneously using conventional combustible waste and coal having relatively good combustibility and combustible waste and coal having poor combustibility.
The structure of a cement kiln burner is disclosed in, for example, Patent Document 1 below. When the velocity of air blown from the burner is increased, the combustibility of fuel blown from the same burner is greatly improved, but when the wind velocity of the burner having the same structure is increased, the airflow rate is also increased at the same time. However, the increase in the airflow rate causes deterioration in the basic unit of heat quantity because fuel for warming the air also needs to be consumed.
Meanwhile, when the burner is manufactured, which has a reduced cross-sectional area of a flow channel for blowing out the air so as to increase the wind velocity in consideration of the above, the combustibility of the fuel can be always maintained in a good state, but when fuel having relatively good combustibility is blown, the combustibility is excessively improved, to cause abnormal short flame, which causes quality abnormality of clinkers, burning of refractory bricks on the inner wall of a kiln, and the like. Therefore, the amount, type, and coal type of the conventionally applied coal substitution are limited. Under such circumstances, a technique capable of adjusting the wind velocity without changing the airflow rate of fluid blown out from the flow channel according to the degree of the combustibility of the fuel is desired.
Therefore, an object of the present invention is to provide a cement kiln burner capable of adjusting a wind velocity without changing the airflow rate of fluid blown out from flow channels according to the degree of combustibility of fuel, and a method for operating the same.
A cement kiln burner of the present invention includes a plurality of columnar or cylindrical flow channels. Outlets of the respective flow channels are disposed on substantially the same plane. A wind velocity adjusting member capable of changing a cross-sectional area at an outlet-side tip-end portion of the flow channel by moving along an axial direction of the flow channel in a state of being in contact with any one of an inner peripheral wall and an outer peripheral wall of the flow channel and not in contact with the other is provided inside at least one of the flow channels.
According to the present invention, by changing the cross-sectional area at the outlet-side tip-end portion of the flow channel by the wind velocity adjusting member, a wind velocity can be adjusted without changing the airflow rate of fluid blown out from the flow channel according to the degree of combustibility of fuel.
In the cement kiln burner of the present invention, the flow channel provided with the wind velocity adjusting member may be configured to form straight air flows. According to this configuration, the wind velocity can be adjusted without changing the airflow rate of the straight air flows.
In the cement kiln burner of the present invention, the flow channel provided with the wind velocity adjusting member may be configured to form swirl air flows having a swirl angle of 1 to 60 degrees. According to this configuration, the wind velocity can be adjusted without changing the airflow rate of the swirl air flows.
In the cement kiln burner of the present invention, each of the plurality of flow channels may be provided with the wind velocity adjusting member. According to this configuration, the airflow rate of the fluid blown out from each of the flow channels can be appropriately adjusted by each of the wind velocity adjusting members.
In the cement kiln burner of the present invention, the wind velocity adjusting member may be provided inside a cylindrical flow channel positioned on an outermost side among the plurality of flow channels. The cylindrical flow channel positioned on an outermost side has a role of collecting primary air in the other flow channels, and therefore the combustibility of the fuel can be easily adjusted by adjusting the wind velocity of the outermost flow channel.
A method for operating a cement kiln burner according to the present invention is a method for operating a cement kiln burner according to any one of the above items, the method including: reducing a cross-sectional area at a tip-end portion of the flow channel by advancing the wind velocity adjusting member toward the outlet side when increasing the wind velocity of the fluid blown out from the flow channel provided with the wind velocity adjusting member; and increasing the cross-sectional area at the tip-end portion of the flow channel by retracting the wind velocity adjusting member from the outlet side when decreasing the wind velocity of the fluid blown out from the flow channel.
According to the present invention, by changing the cross-sectional area at the outlet-side tip-end portion of the flow channel by the wind velocity adjusting member, a wind velocity can be adjusted without changing the airflow rate of fluid blown out from the flow channel according to the degree of combustibility of fuel.
Hereinafter, there will be described embodiments of a cement kiln burner and a method for operating the same, according to the present invention, with reference to the drawings. Incidentally, the drawings which will be described later are schematically illustrated, and dimension ratios in the drawings are not coincident with the actual dimension ratios.
Further, in
As illustrated in
In the powdered-solid-fuel flow channel 2 and the second air flow channel 12, out of the powdered-solid-fuel flow channel 2 and the first and second air flow channels 11 and 12, swirl vanes (2t, 12t) as respective swirl means are secured to the burner tip-end portions in the respective flow channels (see
Meanwhile, no swirl means is provided in the first air flow channel 11. Namely, air flows ejected from the first air flow channel 11 form straight air flows (which will be properly referred to as “straight outer flows”, hereinafter) positioned outside powdered-solid-fuel flows ejected from the powdered-solid-fuel flow channel 2.
A wind velocity adjusting member 5 is provided inside the first air flow channel 11. By moving the wind velocity adjusting member 5 along the axial direction of the first air flow channel 11, the wind velocity can be adjusted without changing the airflow rate of the air blown out from the first air flow channel 11 (will be described in detail later).
Pulverized coal C (one example of “powdered solid fuel”) supplied to a pulverized-coal transfer pipe 21 is supplied to the powdered-solid-fuel flow channel 2 in the cement kiln burner 1, through air flows formed by the blowing fan F1. Air supplied from the blowing fan F2 is supplied, as combustion air A, to the first air flow channel 11 in the cement kiln burner 1, through an air pipe 22. Air supplied from the blowing fan F3 is supplied, as combustion air A, to the second air flow channel 12 in the cement kiln burner 1, through an air pipe 23. A combustible solid waste RF supplied to a combustible-solid-waste transfer pipe 24 is supplied to the combustible-solid-waste flow channel 4 in the cement kiln burner 1, through air flows formed by the blowing fan F4.
The cement kiln burner system 20 illustrated in
Further, heavy oil or the like can be also supplied, through the oil flow channel 3, for being used in ignition in the cement kiln burner 1. Also, solid fuel other than pulverized coal or liquid fuel such as heavy oil can be supplied thereto, for being used in mixed combustion together with pulverized coal, during normal operation (not illustrated).
The wind velocity adjusting member 5 is configured to be movable along the axial direction (Y direction) in the first air flow channel 11. The wind velocity adjusting member 5 is moved along the axial direction by a frontward-rearward moving mechanism (for example, a rack and pinion mechanism) (not illustrated).
The wind velocity adjusting member 5 can change the cross-sectional area at the outlet 11c-side tip-end portion 11d of the first air flow channel 11 by moving along the axial direction in the first air flow channel 11. In
Meanwhile, in the state illustrated in
As described above, the cement kiln burner 1 according to the first embodiment illustrated in
The method for operating the cement kiln burner 1 according to the first embodiment reduces the cross-sectional area at the tip-end portion 11d of the first air flow channel 11 by advancing the wind velocity adjusting member 5 toward the outlet 11c-side of the first air flow channel 11 when increasing the wind velocity of straight outer flows blown out from the first air flow channel 11. As a result, for example, when fuel having poor combustibility is used, the wind velocity of straight outer flows blown out from the first air flow channel 11 can be increased to promote combustion. The method for operating the cement kiln burner 1 according to the first embodiment increases the cross-sectional area at the tip-end portion 11d of the first air flow channel 11 by retracting the wind velocity adjusting member 5 from the outlet 11c side of the first air flow channel 11 when decreasing the wind velocity of straight outer flows blown out from the first air flow channel 11. As a result, for example, when fuel having good combustibility is used, the wind velocity of straight outer flows blown out from the first air flow channel 11 can be lowered to delay combustion.
A second embodiment of a cement kiln burner 1 according to the present invention will be described mainly on differences from the first embodiment. Components common to those of the first embodiment are denoted by the same reference numerals, and the description thereof is appropriately omitted.
In the first embodiment, the example in which the wind velocity adjusting member 5 is provided inside the first air flow channel 11 forming the straight air flows has been described, but the present invention is not limited thereto. For example, as in the second embodiment illustrated in
The wind velocity adjusting member 5 can change the cross-sectional area at the outlet 12c-side tip-end portion 12d of the second air flow channel 12 by moving along the axial direction in the second air flow channel 12. In
A third embodiment of a cement kiln burner 1 according to the present invention will be described mainly on differences from the second embodiment. Components common to those of the second embodiment are denoted by the same reference numerals, and the description thereof is appropriately omitted.
In the second embodiment, the swirl vane 12t is provided so as to completely close the outlet 12c of the second air flow channel 12, but the present invention is not limited thereto. For example, as in the third embodiment illustrated in
By moving the wind velocity adjusting member 5 along the axial direction of the second air flow channel 12, the wind velocity can be adjusted without changing the airflow rate of the air blown out from the second air flow channel 12. Furthermore, a swirl angle by the swirl vane 12t can also be adjusted by changing the airflow rate of the air supplied to the swirl vane 12t. In the state illustrated in
Note that the configuration of the cement kiln burner is not limited to that of the above-described embodiments, and the functions and effects of the cement kiln burner are not limited to those of the above-described embodiments. It is needless to say that various modifications can be made to the cement kiln burner without departing from the gist of the present invention. For example, the configurations, methods, and the like of the plurality of embodiments described above may be optionally adopted and combined. It is a matter of course that one or two or more of configurations, methods, and the like according to various modifications described below may be optionally selected and adopted for the configurations, methods, and the like according to the embodiments described above.
(1) In the first to third embodiments described above, the wind velocity adjusting member 5 is provided inside the cylindrical first or second air flow channel 11 or 12, but the present invention is not limited thereto. For example, the wind velocity adjusting member 5 may be provided inside the columnar combustible-solid-waste flow channel 4 or the cylindrical powdered-solid-fuel flow channel 2 illustrated in
(2)
The cement kiln burner 1a illustrated in
(3) In the above-described embodiments, the wind velocity adjusting member 5 is an integrally formed circular tubular member, but the present invention is not limited thereto. For example, as illustrated in
At least one of the four wind velocity adjusting members 5a illustrated in
As illustrated in
The present inventors evaluated the influence of a wind velocity adjusting member on combustibility by the combustion simulation (software: FLUENT manufactured by ANSYS JAPAN K.K.) of a cement kiln burner.
A cement kiln burner 1b illustrated in
Combustion amount of pulverized coal as powdered solid fuel: 15 t/hour
Processed amount of waste plastic (non-rigid plastic) as combustible solid waste: 3 t/hour
Size of waste plastic as combustible solid waste: a circular sheet having a diameter of 30 mm and formed by punching a sheet having a thickness of 0.5 mm
Amount and temperature of secondary air: 150000 Nm3/hour, 800° C.
Using a wind velocity and a primary air ratio at the outlet of the burner in the following Table 1 as a base (specification), the wind velocity adjusting member provided inside the flow channel was moved from a position where the wind velocity adjusting member was pulled out by 0.5 m from the outlet of the burner to a position where the wind velocity adjusting member was pushed into the outlet (0 mm) of the burner. The wind velocity adjusting member was provided in only one of flow channels (2, 4, 15, 16, 17), and moved. A wind velocity when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was 0.5 mm and a wind velocity when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was 0 mm were as shown in Table 2 below.
The falling rate of waste plastic when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was changed was subjected to simulation analysis. The falling rate of the waste plastic is a ratio of the falling waste plastic among the discharged waste plastic. The evaluation results of the falling rate (% by volume) of the waste plastic are shown in Table 3.
As shown in Table 3, by advancing the wind velocity adjusting member toward the outlet side of the burner and increasing the wind velocity, the combustion of the waste plastic was promoted, and therefore the falling rate of the waste plastic could be reduced.
In the cement kiln burner 1b illustrated in
The maximum gas temperature in the kiln is suitably 1860° C. to 1920° C. from the viewpoint of the heat resistance of bricks in the kiln and the quality of clinkers. The falling rate of the waste plastic is suitably 0% from the viewpoint of the quality of clinkers.
<Burner combustion conditions>, <Waste plastic conditions>, and <Secondary air conditions> are the same as in Example 1.
Based on Table 1 of Example 1, the position of the wind velocity adjusting member provided in the straight outer flow channel 17 was adjusted so that the wind velocity at the outlet of the burner was 400 m/s and 350 m/s.
The maximum temperature (° C.) of gas in the kiln and the falling rate (% by volume) of the waste plastic were subjected to simulation analysis. The evaluation results when the wind velocity at the outlet of the burner is 400 m/s are shown in Table 4, and the evaluation results when the wind velocity at the outlet of the burner is 350 m/s are shown in Table 5.
When the wind velocity at the outlet of the burner shown in Table 4 was 400 m/s, the maximum temperature of gas in the kiln was within a range of 1890° C.±30° C., which was an appropriate temperature, under the condition that the amount of the waste plastic was 3 t/h, whereas when the amount of the waste plastic was less than 3 t/h, the maximum gas temperature increased to outside of the appropriate temperature range, which caused a concern about the erosion of refractory bricks. When the wind velocity at the outlet of the burner shown in Table 5 was 350 m/s, the maximum temperature of gas in the kiln was within the appropriate temperature range under the condition of the amount of the waste plastic of 2 t/h, whereas at the amount of the waste plastic of 3 t/h, the maximum gas temperature decreased to outside of the appropriate temperature range, which caused a concern about deterioration in the quality of clinkers. At the amount of the waste plastic of 1 t/h or less, the maximum temperature increased to outside of the appropriate temperature range, which caused a concern about the erosion of refractory bricks. Namely, it was suggested that the appropriate wind velocity at the outlet of the burner is present according to the amount of the waste plastic, which makes it possible to cope with various amounts of the waste plastic by adjusting the wind velocity at the outlet using the wind velocity adjusting member.
A cement kiln burner 1c illustrated in
Combustion amount of pulverized coal: 3 t/hour
Amount and temperature of secondary air: 160,000 Nm3/hour, 1000° C.
Using a wind velocity and a primary air ratio at the outlet of a burner in the following Table 6 as a base (specification), the wind velocity adjusting member provided inside the flow channel was moved from a position where the wind velocity adjusting member was pulled out by 0.5 m from the outlet of the burner to a position where the wind velocity adjusting member was pushed into the outlet (0 mm) of the burner. The wind velocity adjusting member was provided in only one of the flow channels (13, 14), and moved. A wind velocity when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was 0.5 mm and a wind velocity when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was 0 mm were as shown in Table 7 below.
A pulverized coal combustion rate at an outlet 91a of the calcining furnace 91 when the distance between the tip of the wind velocity adjusting member and the outlet of the burner was changed was subjected to simulation analysis. The evaluation results of the pulverized coal combustion rate (% by weight) are shown in Table 8.
As shown in Table 8, by advancing the wind velocity adjusting member toward the outlet side of the burner and increasing the wind velocity, the combustion of pulverized coal was promoted, and therefore the combustion rate of the pulverized coal could be increased.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/007050 | 2/25/2021 | WO |
