Double-chamber lime shaft kiln suitable for low-heating-value fuel gas
By designing a segmented calcination and preheating structure in a double-bore lime vertical kiln, the problems of increased energy consumption and reduced output caused by low-calorie gas are solved, and fuel consumption and increased lime production are achieved.
Patent Information
- Application Number
- CN202411580404.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-01-14
AI Technical Summary
When low-calorie gas is used for calcining of double-bore lime vertical kilns, the vicious cycle increases the kiln pressure, resulting in increased energy consumption, reduced output and increased calcination costs.
A double-bore lime vertical kiln was designed, with the calcining chamber and the heat storage chamber divided into four sections, with annular passage and spray gun added, and calcining and preheating in sections to reduce airflow resistance, increase air temperature, and reduce fuel consumption.
It effectively reduces the cost of limestone calcination, increases lime production, and improves unit volume production and finished product quality.
Smart Images
Figure CN119306409A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a limestone calcining thermal device, in particular to a double-chamber limestone vertical kiln suitable for low calorific value fuel gas, belonging to the technical field of calcining. Background Art
[0002] The three elements of limestone calcination decomposition include limestone calcination decomposition temperature, limestone calcination decomposition pressure, and limestone calcination decomposition time. The decomposition temperature of limestone under one atmosphere (CO2 pressure) is 900°C, and the decomposition temperature increases with the increase of pressure. The complete decomposition of limestone is also related to the particle size of limestone. The larger the particle size, the longer the decomposition time.
[0003] The kiln types for calcining limestone include single-chamber lime shaft kiln, double-chamber lime shaft kiln, rotary lime kiln, Fokase lime shaft kiln (belonging to single-chamber lime shaft kiln), sleeve lime shaft kiln, etc. Single-chamber lime shaft kiln and double-chamber lime shaft kiln are positive pressure kilns, and the limestone calcining pressure is greater than one atmosphere; rotary lime kiln, Fokase lime shaft kiln (belonging to single-chamber lime shaft kiln), sleeve lime shaft kiln are negative pressure kilns, and the limestone calcining pressure is less than one atmosphere.
[0004] When low calorific value gas is used for calcining in a double-chamber lime shaft kiln, the kiln pressure will inevitably increase due to the large amount of flue gas generated by combustion. The increased kiln pressure will increase the decomposition temperature of limestone, and the increased decomposition temperature will consume more fuel. The increased fuel will increase the flue gas volume and increase the kiln pressure. This vicious cycle leads to increased energy consumption and reduced output of the double-chamber lime shaft kiln, thereby increasing the calcination cost of limestone. Summary of the invention
[0005] The purpose of the present invention is to provide a double-chamber lime shaft kiln suitable for low calorific value fuel gas to reduce fuel consumption, lower the calcination cost of limestone and increase lime production in view of the drawbacks of the prior art.
[0006] To achieve the above object, the present invention adopts the following technical solution: A double-chamber lime shaft kiln suitable for low calorific value fuel gas comprises a calcining chamber and a heat storage chamber, the inner cavity of the calcining chamber is divided into four sections, which are, from top to bottom, an air preheating zone, a calcining zone, a static decomposition zone and a calcining chamber cooling zone, the inner cavity of the heat storage chamber is divided into four sections, which are, from top to bottom, a limestone preheating zone, a storage zone, an extended cooling zone and a storage chamber cooling zone, a plurality of spray guns are installed in the air preheating zone and the limestone preheating zone, and the nozzles of the spray guns are located at the top of the calcining zone and the storage zone; the outer side of the top of the static decomposition zone is provided with a calcining chamber flue gas annular channel connected thereto, the outer side of the top of the extended cooling zone is provided with a heat storage chamber flue gas annular channel connected thereto, and the calcining chamber flue gas annular channel is connected to the heat storage chamber flue gas annular channel through a flue gas connecting channel.
[0007] The above-mentioned double-chamber lime shaft kiln suitable for low calorific value gas is provided with a calcining chamber cooling air annular channel connected to the calcining chamber cooling zone on the outer side of the bottom of the static decomposition zone, and a heat storage chamber cooling air annular channel connected to the heat storage chamber cooling zone is provided on the outer side of the bottom of the extended cooling zone. The calcining chamber cooling air annular channel is connected to the heat storage chamber cooling zone through a cooling air connecting channel.
[0008] The above-mentioned double-chamber lime shaft kiln suitable for low calorific value fuel gas, the calcining chamber flue gas annular channel is higher than the static decomposition zone, the heat storage chamber flue gas annular channel is higher than the extended cooling zone, the bottom of the calcining chamber flue gas annular channel and the top of the static decomposition zone, the bottom of the heat storage chamber flue gas annular channel and the top of the extended cooling zone are connected through multiple radial airways.
[0009] The above-mentioned double-chamber lime shaft kiln suitable for low calorific value gas, the calcining chamber cooling air annular channel is higher than the calcining chamber cooling zone, and the bottom of the calcining chamber cooling air annular channel is connected with the top of the calcining chamber cooling zone; the heat storage chamber cooling air annular channel is higher than the heat storage chamber cooling zone, and the bottom of the heat storage chamber cooling air annular channel is connected with the top of the heat storage chamber cooling zone.
[0010] The above-mentioned double-chamber lime shaft kiln suitable for low calorific value gas has a plurality of lances and a plurality of radial gas passages evenly distributed around the axis of the calcining chamber and the heat storage chamber.
[0011] The above-mentioned double-chamber lime shaft kiln suitable for low calorific value gas, the shapes of the air preheating zone, calcining zone, static decomposition zone, calcining chamber flue gas annular channel, calcining chamber cooling air annular channel and calcining chamber cooling zone in the calcining chamber are respectively the same as the shapes of the limestone preheating zone, storage zone, extended cooling zone, storage chamber flue gas annular channel, storage chamber cooling air annular channel and storage chamber cooling zone in the regenerative chamber.
[0012] The present invention divides the calcining zone and the heat storage zone into two sections by adding an annular channel, which can reduce the air flow resistance of the calcining chamber, reduce the amount of cooling air in the heat storage chamber, and increase the wind temperature entering the heat storage zone. This reduces fuel consumption, reduces the calcining cost of limestone, and increases lime production. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0014] Figure 1 It is a schematic diagram of the structure of the present invention ( Figure 3 DD section view in ); Figure 2 yes Figure 1 AA section view in; Figure 3 yes Figure 1 BB section view in; Figure 4 yes Figure 1 CC section view in.
[0015] The numbers in the figure are as follows: 1. calcining chamber, 2. heat storage chamber, 3. spray gun, 4. air preheating zone, 5. limestone preheating zone, 6. calcining zone, 7. heat storage zone, 8. calcining chamber flue gas annular channel, 9. heat storage chamber flue gas annular channel, 10. flue gas connecting channel, 11. calcining chamber cooling air annular channel, 12. heat storage chamber cooling air annular channel, 13. cooling air connecting channel, 14. static decomposition zone, 15. extended cooling zone, 16. calcining chamber cooling zone, 17. heat storage chamber cooling zone, 18. radial air channel. DETAILED DESCRIPTION
[0016] In order to ensure that the limestone is fully decomposed, the present invention divides the calcination zone in the calcination chamber of the lime kiln into two sections, the upper section is still the calcination zone, and the heat generated by the combustion of gas is used to decompose the limestone, and the lower section is used as a static decomposition zone, which uses hot lime to continue to decompose the incompletely decomposed limestone. The decomposition of limestone is carried out gradually from the outside to the inside, which is an endothermic reaction. First, the surface of the limestone absorbs the heat of the flue gas, and the surface of the limestone decomposes. The high-temperature surface transfers heat to the inside of the limestone, causing the inside to decompose. It is based on this principle that the calcination and decomposition of limestone can be divided into two sections. The structure of the heat storage chamber is exactly the same as that of the calcination chamber, but the names of the sections in the inner cavity are different.
[0017] See also Figure 1-Figure 4 The present invention comprises a cylindrical calcining chamber 1 and a heat storage chamber 2. The inner cavity of the calcining chamber 1 is divided into four sections, which are an air preheating zone 4, a calcining zone 6, a static decomposition zone 14 and a calcining chamber cooling zone 16 from top to bottom. The inner cavity of the heat storage chamber 2 is divided into four sections, which are a limestone preheating zone 5, a heat storage zone 7, an extended cooling zone 15 and a heat storage chamber cooling zone 17 from top to bottom. A plurality of spray guns 3 are installed in the air preheating zone 4 of the calcining chamber 1 and the limestone preheating zone 5 of the heat storage chamber 2. The nozzles of the spray guns 3 face downward and are located at the top of the calcining zone 6 and the heat storage zone 7; a calcining chamber flue gas annular channel 8 connected to the static decomposition zone 14 is provided on the outer side of the top, and a heat storage chamber flue gas annular channel 9 connected to the extended cooling zone 15 is provided on the outer side of the top, and the calcining chamber flue gas annular channel 8 and the heat storage chamber flue gas annular channel 9 are connected through a flue gas connecting channel 10. A calcining chamber cooling air annular channel 11 connected to the calcining chamber cooling zone 16 is provided on the bottom outer side of the static decomposition zone 14, and a heat storage chamber cooling air annular channel 12 connected to the heat storage chamber cooling zone 17 is provided on the bottom outer side of the extended cooling zone 15. The calcining chamber cooling air annular channel 11 and the heat storage chamber cooling air annular channel 12 are connected via a cooling air connecting channel 13.
[0018] The calcining chamber flue gas annular channel 8 is higher than the static decomposition zone 14, and the heat storage chamber flue gas annular channel 9 is higher than the extended cooling zone 15. The bottom of the calcining chamber flue gas annular channel 8 and the top of the static decomposition zone 14, and the bottom of the heat storage chamber flue gas annular channel 9 and the top of the extended cooling zone 15 are connected through multiple radial airways 18.
[0019] The calcining chamber cooling air annular channel 11 is higher than the calcining chamber cooling zone 16, and the bottom of the calcining chamber cooling air annular channel 11 is connected to the top of the calcining chamber cooling zone 16; the heat storage chamber cooling air annular channel 12 is higher than the heat storage chamber cooling zone 17, and the bottom of the heat storage chamber cooling air annular channel 12 is connected to the top of the heat storage chamber cooling zone 17.
[0020] A plurality of lances 3 and a plurality of radial gas passages 18 are evenly distributed around the axes of the calcining chamber 1 and the regenerating chamber 2 .
[0021] The shapes of the air preheating zone 4, calcining zone 6, static decomposition zone 14, calcining chamber flue gas annular channel 8, calcining chamber cooling air annular channel 11 and calcining chamber cooling zone 16 in the calcining chamber 1 are exactly the same as those of the limestone preheating zone 5, storage zone 7, extended cooling zone 15, storage chamber flue gas annular channel 9, storage chamber cooling air annular channel 12 and storage chamber cooling zone 17 in the regenerative chamber 2, and can be interchanged during operation.
[0022] The working process of the present invention is as follows: Limestone calcining process: The gas sprayed from the lance 3 in the calcining chamber 1 is mixed with the air supplied from the kiln top and then burns in the calcining chamber 1, providing heat for the calcination and decomposition of the limestone. The hot flue gas generated by the combustion runs synchronously from top to bottom with the limestone to achieve the calcination of the limestone. After the hot flue gas in the calcining chamber 1 completes the heat exchange with the limestone, it enters the heat storage chamber 2 through the calcining chamber flue gas annular channel 8, the flue gas connecting channel 10, and the heat storage chamber flue gas annular channel 9, and is discharged from the kiln chamber through the heat storage chamber 2 to achieve the calcination of the limestone.
[0023] The cooling process of lime: cooling air enters the calcining chamber cooling zone 16 and the heat storage chamber cooling zone 17 from the bottom at the same time to cool the lime after calcination. After the cooling air exchanges heat with the lime, the cooling air of the calcining chamber 1 enters the heat storage chamber 2 through the calcining chamber cooling air annular channel 11, the cooling air connecting channel 13, and the heat storage chamber cooling air annular channel 12, and merges with the cooling air of the heat storage chamber 2 to enter the extended cooling zone 15 of the heat storage chamber 2 to continue to exchange heat with the lime. The cooling air of the calcining chamber cooling zone 16 and the heat storage chamber cooling zone 17 is a countercurrent heat exchange with the lime. The temperature of the cooling air after the exchange is ≥800°C, and it continues to ascend and merges with the hot flue gas to form a high-temperature mixed gas. The temperature of the high-temperature mixed gas is ≥900°C.
[0024] The high-temperature mixed gas passes through the heat storage zone 7 and enters the limestone preheating zone 5 for countercurrent heat exchange with the limestone. The mixed gas cooled after the heat exchange is discharged from the top of the heat storage chamber 2.
[0025] The combustion flue gas in the calcining zone provides heat for the decomposition of limestone, the red-hot lime in the outer layer of the static decomposition zone provides heat for the undecomposed limestone in the inner layer, the red-hot lime in the outer layer of the thermal storage zone can provide heat for the undecomposed limestone in the inner layer, and the mixed gas can also supplement a certain amount of heat to the lime.
[0026] The beneficial effects of the present invention are as follows: by adding an annular channel to divide the calcining zone and the heat storage zone into two sections, the air flow resistance of the calcining chamber can be reduced, the heat storage chamber increases the height of the cooling zone and reduces the height of the heat storage zone, reduces the amount of cooling air, and increases the wind temperature entering the heat storage zone. This increases the unit volume output, reduces the unit product fuel consumption, and improves the quality of the finished product.
Claims
1. A double-chamber lime shaft kiln suitable for low calorific value gas, characterized in that: The invention comprises a calcining chamber (1) and a heat storage chamber (2). The inner cavity of the calcining chamber (1) is divided into four sections, which are, from top to bottom, an air preheating zone (4), a calcining zone (6), a static decomposition zone (14) and a calcining chamber cooling zone (16). The inner cavity of the heat storage chamber (2) is divided into four sections, which are, from top to bottom, a limestone preheating zone (5), a heat storage zone (7), an extended cooling zone (15) and a heat storage chamber cooling zone (17). A plurality of spray guns (3) are installed, and the nozzles of the spray guns (3) are located at the top of the calcining zone (6) and the heat storage zone (7); the top outer side of the static decomposition zone (14) is provided with a calcining chamber flue gas annular channel (8) connected thereto, and the top outer side of the extended cooling zone (15) is provided with a heat storage chamber flue gas annular channel (9) connected thereto; the calcining chamber flue gas annular channel (8) and the heat storage chamber flue gas annular channel (9) are connected via a flue gas connecting channel (10).
2. A double-chamber lime shaft kiln suitable for low calorific value gas according to claim 1, characterized in that: The bottom outer side of the static decomposition zone (14) is provided with a calcining chamber cooling air annular channel (11) communicating with the calcining chamber cooling zone (16); the bottom outer side of the extended cooling zone (15) is provided with a regenerative chamber cooling air annular channel (12) communicating with the regenerative chamber cooling zone (17); the calcining chamber cooling air annular channel (11) is communicated with the regenerative chamber cooling air annular channel (12) via a cooling air connecting channel (13).
3. A double-chamber lime shaft kiln suitable for low calorific value fuel gas according to claim 2, characterized in that: The calcining chamber flue gas annular channel (8) is higher than the static decomposition zone (14), and the regenerative chamber flue gas annular channel (9) is higher than the extended cooling zone (15). The bottom of the calcining chamber flue gas annular channel (8) and the top of the static decomposition zone (14), as well as the bottom of the regenerative chamber flue gas annular channel (9) and the top of the extended cooling zone (15) are both connected via a plurality of radial air passages (18).
4. A double-chamber lime shaft kiln suitable for low calorific value fuel gas according to claim 3, characterized in that: The calcining chamber cooling air annular channel (11) is higher than the calcining chamber cooling zone (16), and the bottom of the calcining chamber cooling air annular channel (11) is connected to the top of the calcining chamber cooling zone (16); the heat storage chamber cooling air annular channel (12) is higher than the heat storage chamber cooling zone (17), and the bottom of the heat storage chamber cooling air annular channel (12) is connected to the top of the heat storage chamber cooling zone (17).
5. A double-chamber lime shaft kiln suitable for low calorific value fuel gas according to claim 4, characterized in that: A plurality of lances (3) and a plurality of radial gas passages (18) are evenly distributed around the axes of the calcining chamber (1) and the regenerating chamber (2).
6. A double-chamber lime shaft kiln suitable for low calorific value fuel gas according to claim 5, characterized in that: The shapes of the air preheating zone (4), calcining zone (6), static decomposition zone (14), calcining chamber flue gas annular channel (8), calcining chamber cooling air annular channel (11) and calcining chamber cooling zone (16) in the calcining chamber (1) are respectively the same as the shapes of the limestone preheating zone (5), thermal storage zone (7), extended cooling zone (15), thermal storage chamber flue gas annular channel (9), thermal storage chamber cooling air annular channel (12) and thermal storage chamber cooling zone (17) in the thermal storage chamber (2).