Pre-combustion system suitable for large-granularity high-density alternative fuel

Abstract

The invention relates to the technical field of alternative fuels used in cement kilns, and discloses a pre-combustion system suitable for large-granularity high-density alternative fuels, which comprises a preheater, a rotary kiln, a smoke chamber, a decomposing furnace, a cooling machine, a rotary pre-combustion furnace, an air locking feeding system, a cooling machine middle section suction opening and a cooling machine tail section suction opening, the rotary pre-combustion furnace is composed of an air inlet, a feeding port, a barrel, a transmission device and an air outlet. The rotary pre-combustion furnace is used as a large-granularity and high-density alternative pre-combustion device, alternative fuel is turned over in the barrel through rotation of the rotary pre-combustion furnace, the contact area between the alternative fuel and hot air is larger, aerobic combustion is facilitated, hot air is extracted through the cooling machine middle section and the cooling machine tail end respectively, and then control is conducted through the air valve and the flow meter, so that the cooling efficiency is improved. The temperature and the air volume of hot air for alternative fuel combustion in the rotary pre-combustion furnace are controllable, the temperature in the rotary pre-combustion furnace can be controlled easily, and ash is prevented from being burnt and melted due to the fact that the temperature is too high.

Description

Technical Field

[0001] The invention relates to the technical field of cement kiln utilizing alternative fuels, in particular to a pre-combustion system suitable for large-particle-size and high-density alternative fuels. Background Art

[0002] With the increasing consumption of fossil fuels, fossil fuels are becoming increasingly scarce. The cement industry is a major consumer of fossil fuels, making coal resources increasingly scarce. The use of alternative fuels is an inevitable industrial route for the cement industry.

[0003] Since the two core thermal equipments of cement industry, decomposition furnace and rotary kiln, have their own characteristics, the rotary kiln needs to be equipped with high-efficiency burners to produce certain flame temperature and flame status to meet the requirements of clinker calcination, and has relatively strict requirements on fuel and alternative fuels. The use of alternative fuels in the kiln head burner requires the alternative fuels to have certain calorific value and fineness, and needs to meet the requirements of burner combustion speed, flame temperature, etc., and also needs to meet the requirements of pneumatic conveying and ejection. Therefore, the kiln head needs to use alternative fuels with high calorific value, fast combustion speed and smaller than a certain particle size, and has relatively strict requirements on the pretreatment system; the main function of the decomposition furnace is to realize the suspended decomposition of raw materials. The decomposition furnace has its own unique performance: furnace capacity or flue gas residence time, suspension and support of raw materials and coal powder, etc. The use of alternative fuels needs to meet the requirements of the decomposition furnace. The particle size and density need to meet the requirements of being suspended and supported by flue gas in the decomposition furnace, and the combustion time needs to be less than the residence time in the decomposition furnace. Therefore, the particle size of the alternative fuel cannot be too large and the density cannot be too high.

[0004] Due to the characteristics of rotary kilns and decomposition furnaces, alternative fuels in the cement industry must be screened or pretreated. However, the use of alternative fuels in China is in its early stages. Although some alternative fuel resources, such as domestic waste, industrial waste, and solid waste, have certain calorific values, they are not classified. The collected alternative fuel resources are often a mixture of various types of uneven particle sizes, large differences in calorific values, and large differences in moisture. There are many metal and non-metal impurities, which brings certain difficulties to pretreatment.

[0005] It is difficult for the kiln head burner to adapt to alternative fuels with higher density and larger particle size. Although the decomposition furnace can handle it, there are still problems such as difficulty in suspension, large fluctuations in the thermal parameters of the decomposition furnace, low burnout rate, and impact on raw material decomposition and clinker calcination. At the same time, the cement kiln system requires a certain reduction in production.

[0006] In order to reduce the adverse effects of alternative fuels with high density and large particle size on decomposition furnaces and rotary kilns, pre-combustion devices are used to pre-dry and pre-combust large-particle and high-density alternative fuels, and then connect them to the cement kiln system after combustion. At present, the cement industry generally uses step furnaces, pipe furnaces, hot plate furnaces, etc. as pre-combustion devices for alternative fuels, but for large-particle and high-density alternative fuels, these three pre-combustion devices all have their disadvantages: the step furnace has the disadvantage that the alternative fuel sinks to the bottom and the hot air is on the top, and oxygen is difficult to sink to the bottom, resulting in a slow combustion speed in the step furnace, and part of the hot air is not used for combustion and directly goes away from the step furnace; the principle of the pipe furnace is similar to that of the decomposition furnace, and the alternative fuel still needs to reduce the particle size to be suspended and burned in the pipe furnace, which is consistent with the particle size requirements of the direct combustion of the decomposition furnace for the alternative fuel; the hot plate furnace has better adaptability to large-particle and high-density alternative fuels, and even large pieces can be guaranteed by the speed control of the hot plate furnace to ensure the combustion residence time, but the hot plate furnace also has the disadvantage that the alternative fuel sinks to the bottom and the hot air is on the top.

[0007] In order to solve the problem of large-particle and high-density alternative fuels sinking to the bottom and hot air stratification, it is necessary to find a new pre-combustion technology and equipment to make the alternative fuel and hot air mix better, which is conducive to sufficient oxygen guarantee for fuel combustion and reasonable excess oxygen. Therefore, it is very necessary to propose a pre-combustion system suitable for large-particle and high-density alternative fuels. Summary of the invention

[0008] Technical issues solved

[0009] In view of the deficiencies of the prior art, the present invention provides a pre-combustion system suitable for large-particle and high-density alternative fuels, mainly to solve the problem of large-particle and high-density alternative fuels sinking to the bottom and hot air stratification.

[0010] Technical Solution

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A precombustion system suitable for large-particle and high-density alternative fuels comprises a preheater, a rotary kiln, a smoke chamber, a decomposition furnace and a cooler. The precombustion system also comprises a rotary precombustion furnace, an air-locking feeding system, a middle exhaust port of the cooler and a rear exhaust port of the cooler. The rotary precombustion furnace comprises an air inlet, a feed port, a cylinder, a transmission device, an air outlet and a slag outlet. The air inlet is connected to the middle exhaust port of the cooler and the rear exhaust port of the cooler, the air outlet is connected to the middle of the decomposition furnace through a pipeline, the slag outlet is connected to the smoke chamber, the air-locking feeding system comprises a feeding chute, a first pneumatic valve, a second pneumatic valve and a spiral feeding device, and the air-locking feeding system is connected to the feed port of the rotary precombustion furnace.

[0013] Furthermore, a first air valve and a first flow meter are arranged on the air duct between the air inlet and the exhaust port in the middle section of the cooler, and a second air valve and a second flow meter are arranged on the air duct between the air inlet and the exhaust port in the rear section of the cooler.

[0014] On the basis of the above scheme, the air outlet of the rotary precombustion furnace is connected to the middle part of the decomposition furnace through an air outlet hood and an air outlet pipe. The wind speed of the air outlet hood section is 5m / s, and the wind speed of the air outlet pipe is 10m / s. The air outlet pipe is connected to the middle part of the decomposition furnace and is located 6m above the entrance of the tertiary air duct and the decomposition furnace. The slag outlet of the rotary precombustion furnace is located at the discharge end of the rotary precombustion furnace, and the slag outlet is connected to the cylinder through a sealing device.

[0015] As a further solution of the present invention, a slag chute is arranged at the lower part of the air outlet hood of the rotary precombustion furnace, the slag outlet is connected to the smoke chamber through the slag chute, and a wind-locking flap valve is arranged on the slag chute.

[0016] Furthermore, the cylinder has a certain inclination, the angle between the center line of the cylinder and the horizontal plane is 5°, the rotation speed is 10r / min, and the rotation speed is controlled by a transmission device.

[0017] Beneficial Effects

[0018] Compared with the prior art, the present invention provides a pre-combustion system suitable for large-particle high-density alternative fuels, which has the following beneficial effects:

[0019] 1. The present invention uses a rotary pre-combustion furnace as a large-particle, high-density alternative pre-combustion device. The rotation of the rotary pre-combustion furnace causes the alternative fuel to turn over in the cylinder, so that the contact area with the hot air is larger, which is conducive to aerobic combustion.

[0020] 2. The present invention extracts hot air through the middle section and the tail end of the cooler respectively, and then controls it through the air valve and flow meter, so that the temperature and air volume of the hot air for burning alternative fuels in the rotary precombustion furnace can be controlled, which is beneficial to controlling the temperature in the rotary precombustion furnace to prevent the ash from being burned due to excessive temperature.

[0021] 3. The rotary pre-combustion furnace of the present invention is designed with a low-slope, high-speed cylinder, which not only increases the number of turnovers of the alternative fuel, but also ensures the residence time of the alternative fuel in the rotary pre-combustion furnace, which is beneficial to the full contact between the alternative fuel and the oxygen-containing hot air and improves the burnout rate of the alternative fuel.

[0022] 4. The rotary pre-combustion furnace of the present invention separates flue gas and ash at its outlet, and the flue gas enters the middle part of the decomposition furnace (above the inlet of the tertiary air duct and close to the discharge pipe), which reduces the impact on the fuel combustion of the decomposition furnace, is beneficial to the decomposition of the raw material, and further completes the further combustion of the unburned alternative fuel (fine particles and volatile matter) carried in the flue gas; the ash enters the rotary kiln and is calcined into clinker together with the hot raw material, thereby realizing the complete consumption of the alternative fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a process flow diagram of a pre-combustion system suitable for large-particle-size and high-density alternative fuels proposed by the present invention;

[0024] Figure 2 A schematic diagram of a rotary pre-combustion furnace and an air-locking feeding system for a pre-combustion system of large-particle-size and high-density alternative fuels proposed by the present invention;

[0025] Figure 3 The present invention proposes a pre-combustion system suitable for large-particle high-density alternative fuels. Figure 1 A-direction view.

[0026] In the figure: 1. preheater; 2. rotary kiln; 3. smoke chamber; 4. decomposition furnace; 4-1. entrance of decomposition furnace; 5. rotary precombustion furnace; 5-1. air inlet; 5-2. feed inlet; 5-3. cylinder; 5-4. transmission device; 5-5. air outlet; 5-5-1. air outlet hood; 5-5-2. air outlet pipe; 5-6. slag outlet; 6. air-locking feeding system; 6-1. feeding chute; 6-2. first pneumatic valve; 6-3. second pneumatic valve; 6-4. spiral feeding device; 7. cooler; 7-1. exhaust port of middle section of cooler; 7-2. exhaust port of tail section of cooler; 8-1. first air valve; 8-2. second air valve; 9. first flow meter; 10. second flow meter; 11. sealing device; 12. slag outlet; 12-1. air-locking flap valve. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Reference Figure 1-Figure 3A pre-combustion system suitable for large-size and high-density alternative fuels includes a preheater 1, a rotary kiln 2, a smoke chamber 3, a decomposition furnace 4, and a cooler 7. The pre-combustion system also includes a rotary pre-combustion furnace 5, a wind-locking feeding system 6, a cooler middle section exhaust port 7-1, and a cooler tail section exhaust port 7-2. The rotary pre-combustion furnace 5 is composed of an air inlet 5-1, a feed port 5-2, a cylinder 5-3, a transmission device 5-4, an air outlet 5-5, and a slag outlet 5-6. -6, the air inlet 5-1 is connected with the exhaust port 7-1 in the middle section of the cooler and the exhaust port 7-2 in the rear section of the cooler, the air outlet 5-5 is connected with the middle part of the decomposition furnace 4 through a pipeline, the slag outlet 5-6 is connected with the smoke chamber 3, the air-locking feeding system 6 is composed of a feeding chute 6-1, a first pneumatic valve 6-2, a second pneumatic valve 6-3, and a spiral feeding device 6-4, and the air-locking feeding system 6 is connected with the feed port 5-2 of the rotary pre-combustion furnace 5.

[0029] In particular, in the present invention, in order to further improve the air volume accuracy of the medium-temperature hot air in the middle section of the cooler 7 and the low-temperature hot air at the rear end, the hot air temperature and heat content or oxygen supply of the hot air entering the rotary precombustion furnace 5 have been regulated to meet the combustion of alternative fuels, and a first air valve 8-1 and a first flow meter 9 are arranged on the air duct between the air inlet 5-1 and the exhaust port 7-1 in the middle section of the cooler, and a second air valve 8-2 and a second flow meter 10 are arranged on the air duct between the air inlet 5-1 and the exhaust port 7-2 at the rear end of the cooler.

[0030] It should be noted that the air outlet 5-5 of the rotary precombustion furnace 5 is connected to the middle part of the decomposition furnace 4 through the air outlet hood 5-5-1 and the air outlet pipe 5-5-2. The wind speed of the cross section of the air outlet hood 5-5-1 is ≤5m / s, the wind speed of the air outlet pipe 5-5-2 is 10-15m / s, the air outlet pipe 5-5-2 is connected to the middle part of the decomposition furnace 4 and is located 3 to 6m above the tertiary air duct and the inlet 4-1 of the decomposition furnace; the slag outlet 5-6 of the rotary precombustion furnace 5 is located at the discharging end of the rotary precombustion furnace 5, and the slag outlet 5-6 is connected to the cylinder 5-3 through a sealing device 11. The cylinder 5-3 has a certain inclination, and the angle between the center line of the cylinder 5-3 and the horizontal plane is 1 to 5°C. The rotation speed is 3-10r / min, and the rotation speed is controlled by the transmission device 5-4, which not only ensures the rotation of the rotary precombustion furnace 5, but also reduces the air leakage rate of the rotary precombustion furnace 5.

[0031] A slag chute 12 is arranged at the lower part of the air outlet hood 5-5-1 of the rotary precombustion furnace 5 in the present invention, and the slag outlet 5-6 is connected to the smoke chamber 3 through the slag chute 12. A wind locking flap valve 12-1 is arranged on the slag chute 12 to ensure that the ash enters the smoke chamber 3 while preventing the gas in the smoke chamber 3 from leaking upward.

[0032] Working principle of this embodiment: When in use, large-size and high-density alternative fuel is metered and fed into the rotary pre-combustion furnace 5 through the air-locking feeding system 6 and the feed port 5-2. The middle hot air and / or the tail hot air from the cooler 7 are regulated by the first air valve 8-1 and the first flow meter 9, the second air valve 8-2 and the second flow meter 10 according to the feed amount of the alternative fuel, the calorific value of the performance characteristics, etc., to determine the amount and temperature of hot air entering the rotary pre-combustion furnace 5. The alternative fuel is dried, pre-combusted and burned in the rotary pre-combustion furnace 5 after ignition. The rotation speed of the cylinder 5-3 is controlled according to the performance of the alternative fuel, so that the alternative fuel can be turned over multiple times in the rotary pre-combustion furnace 5, so that the hot air is fully in contact with the alternative fuel; the smaller inclination of the cylinder 5-3 is controlled so that the alternative fuel Although the turnover is relatively frequent, the combustion residence time is guaranteed, which is conducive to improving the burnout degree of the alternative fuel; after a certain period of turnover and combustion, the particle size of the alternative fuel gradually decreases, and the high-temperature flue gas formed after combustion enters the decomposition furnace 4 through the air outlet 5-5, the air outlet hood 5-5-1, and the air outlet pipe 5-5-2, to assist the decomposition of the raw material, and further burn out the volatile matter or unburned small particles of alternative fuel carried in the flue gas; the unburned alternative fuel with a certain particle size and the ash formed after the combustion of the alternative fuel enter the smoke chamber 3, and enter the rotary kiln 2 together with the preheated raw material from the preheater 1, and complete the burnout of the unburned alternative fuel in the rotary kiln 2, and the heat released during the combustion is used together with the heat generated by the combustion of the kiln head burner to supply the clinker in the rotary kiln 2.

[0033] The electrical components mentioned in this article are all connected to an external main controller and 220V mains electricity, and the main controller can be a conventional known device for controlling a computer or the like.

[0034] In the description of this article, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In the description of this article, it should be noted that relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pre-combustion system suitable for large-size and high-density alternative fuels, comprising a preheater (1), a rotary kiln (2), a smoke chamber (3), a decomposition furnace (4), and a cooler (7), characterized in that: The pre-combustion system further comprises a rotary pre-combustion furnace (5), an air-locking feeding system (6), a middle section air exhaust port (7-1) of a cooler, and a rear section air exhaust port (7-2) of a cooler. The rotary pre-combustion furnace (5) comprises an air inlet (5-1), a feed port (5-2), a cylinder (5-3), a transmission device (5-4), an air outlet (5-5), and a slag outlet (5-6). The air inlet (5-1) and the middle section air exhaust port (7-1) of the cooler are connected to each other. , the exhaust port (7-2) at the rear section of the cooler is connected, the air outlet (5-5) is connected to the middle of the decomposition furnace (4) through a pipeline, the slag outlet (5-6) is connected to the smoke chamber (3), the air-locking feeding system (6) is composed of a feeding chute (6-1), a first pneumatic valve (6-2), a second pneumatic valve (6-3), and a spiral feeding device (6-4), and the air-locking feeding system (6) is connected to the feed port (5-2) of the rotary pre-combustion furnace (5).

2. A pre-combustion system for large particle size and high density alternative fuel according to claim 1, characterized in that: A first air valve (8-1) and a first flow meter (9) are arranged on the air duct between the air inlet (5-1) and the exhaust port (7-1) of the middle section of the cooler, and a second air valve (8-2) and a second flow meter (10) are arranged on the air duct between the air inlet (5-1) and the exhaust port (7-2) of the rear section of the cooler.

3. A pre-combustion system for large particle size and high density alternative fuel according to claim 1, characterized in that: The air outlet (5-5) of the rotary pre-combustion furnace (5) is connected to the middle of the decomposition furnace (4) through an air outlet hood (5-5-1) and an air outlet pipe (5-5-2); the wind speed of the cross section of the air outlet hood (5-5-1) is 5 m / s, the wind speed of the air outlet pipe (5-5-2) is 10 m / s, the air outlet pipe (5-5-2) is connected to the middle of the decomposition furnace (4) and is located 6 m above the tertiary air duct and the entrance (4-1) of the decomposition furnace; the slag outlet (5-6) of the rotary pre-combustion furnace (5) is located at the discharge end of the rotary pre-combustion furnace (5), and the slag outlet (5-6) is connected to the cylinder (5-3) through a sealing device (11).

4. A pre-combustion system for large particle size and high density alternative fuel according to claim 1 or 3, characterized in that: A slag chute (12) is arranged at the lower part of the air outlet cover (5-5-1) of the rotary pre-combustion furnace (5); the slag outlet (5-6) is connected to the smoke chamber (3) through the slag chute (12); and a wind-locking flap valve (12-1) is arranged on the slag chute (12).

5. A pre-combustion system for large particle size and high density alternative fuel according to claim 3, characterized in that: The cylinder (5-3) has a certain inclination, the angle between the center line of the cylinder (5-3) and the horizontal plane is 5°, the rotation speed is 10r / min, and the rotation speed is controlled by the transmission device (5-4).

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