High-proportion alternative fuel pre-treatment and cement kiln incineration system and method

Abstract

The present invention relates to the technical field of alternative fuel in the cement industry. Disclosed is a high-proportion alternative fuel pre-treatment and cement kiln incineration system, comprising a stacking shed, a storage system, a rotary kiln, a pulverized coal burner, a cooler, a tertiary air duct and a preheated raw-material preheater; and further comprising a crushing system, a homogenization system, metering systems, conveying systems, gravity-type feeding systems, a multifunctional decomposition furnace, a special combustor for alternative fuel, and a pneumatic conveying system. In the present invention, the particle size of crushed alternative fuel is controlled on the basis of a flue gas suspension speed, such that the alternative fuel combusts in a suspended manner in the multifunctional decomposition furnace; the alternative fuel is metered by means of the three metering systems, and the alternative fuel in one path is fed into the special combustor; the special combustor and the pulverized coal combustor are arranged one above the other in the rotary kiln, and pulverized coal combustion is used to drive the combustion of the alternative fuel; and the gravity-type feeding systems and their respective two airlock discharge valves, which are alternately opened, are used to feed in the alternative fuel, thereby reducing air leakage during a feeding process.

Description

High-proportion alternative fuel pretreatment cement kiln incineration system and method TECHNICAL FIELD

[0001] The present application relates to the technical field of alternative fuels in the cement industry, and more particularly to a high-proportion alternative fuel pretreatment cement kiln incineration system and method. BACKGROUND

[0002] With the consumption of fossil fuels, the reserves of fossil fuels such as coal are gradually decreasing, and fossil energy such as coal is becoming increasingly scarce. In addition, the cement industry is calling for a "carbon peak and carbon neutral" appeal, and the use of alternative fuels to replace traditional fossil fuels is a good choice for energy utilization. The proportion of alternative fuels in the cement industry in Europe and other developed countries is much higher than that in China. With the progress of technology and the recognition of energy, the use of alternative fuels as a heat source for new dry cement firing systems has gradually emerged in the cement industry. However, due to the lower calorific value of alternative fuels compared to fossil fuels, as well as high moisture content and difficulty in combustion, the substitution rate is low.

[0003] The use of partial alternative fuels in the cement kiln system increases the amount of flue gas, and the wind speed of the decomposing furnace and preheater system increases, resulting in a shorter residence time of flue gas and fuel in the decomposing furnace, which further exacerbates the low burnout rate of alternative fuels. The delayed combustion of alternative fuels into the preheater system continues to burn, resulting in a temperature inversion in the decomposing furnace and preheater, causing local high temperatures in the preheater system and the risk of skinning and plugging.

[0004] To increase the proportion of alternative fuels, the cement industry currently generally uses an additional pre-combustion furnace, such as a ladder furnace, a rotary furnace, a grate furnace, a fluidized bed furnace, a hot disc furnace, and a gasification furnace, which are external extension technologies in the field of waste incineration. The principle is to use an additional combustion furnace or gasification furnace to burn or even burn out the difficult-to-burn alternative fuels in the decomposing furnace, and then send the unburned alternative fuels and generated flue gas into the decomposing furnace to reduce the combustion burden of the decomposing furnace. Due to the higher calorific value of alternative fuels compared to general waste, the temperature generated by the combustion of the additional preheating furnace is relatively high, which can easily cause coking, and the addition of raw materials is required for decomposition and heat absorption. Since raw materials are fine powders, the pre-combustion furnace is not suitable for powders, especially grate furnaces, rotary furnaces, and gasification furnaces. The higher the calorific value of alternative fuels, the greater the risk of coking, the more raw materials needed to be added, and the worse the combustion environment of the pre-combustion furnace.

[0005] In addition, the calcination of clinker in the rotary kiln requires high flame temperature and flame intensity. The alternative fuel is difficult to quickly ignite and burn due to its low calorific value, and the alternative fuel is often replaced at the kiln tail, and fossil fuel is still used at the kiln head. Even if the alternative fuel has a higher calorific value, ordinary coal, oil or natural gas burners are difficult to meet the requirements, and special burners for alternative fuels need to be developed. Since it is difficult to achieve 100% use of alternative fuels in the kiln, special burners for alternative fuels often have the function of mixed combustion of fossil fuels and alternative fuels, which brings difficulty to the adaptability of special burners. In the special burner for alternative fuels, there is a central alternative fuel channel and a peripheral pulverized coal channel. Due to the difference in combustion performance between coal and alternative fuels, the alternative fuels and coal are sprayed from the same burner, and the alternative fuels have a great negative impact on the combustion of pulverized coal, affecting the normal combustion of pulverized coal. Therefore, the use of alternative fuels at the kiln head is still a difficult problem, which limits the development of alternative fuels with high replacement rate.

[0006] Currently, the calorific value replacement rate of alternative fuels in the domestic new dry process cement kiln system is relatively low, with an average of less than 5%, and the highest replacement rate is about 40%. Most of the alternative fuels are used at the kiln tail. In order to improve the calorific value replacement rate of alternative fuels and improve the adaptability of the two major thermal equipment (decomposition furnace and rotary kiln) of the cement kiln system to alternative fuels, key thermal equipment such as special burners for decomposition furnaces and kiln heads need to be developed to adapt to alternative fuels. At the same time, the calorific value control and particle size processing control of alternative fuels need to be carried out to improve the adaptability of alternative fuels to the new dry process cement process. SUMMARY

[0007] In order to overcome the above-mentioned defects of the prior art, the present application provides a high-proportion alternative fuel pretreatment cement kiln incineration system and method. The use proportion of alternative fuels at the kiln head and the kiln tail is improved through the development of a multifunctional decomposition furnace structure at the kiln tail and the development of a special burner for alternative fuels at the kiln head, thereby improving the use proportion of alternative fuels in the entire cement kiln system. The replacement rate of alternative fuels is increased to more than 60%, and the amount of fossil fuels used in the cement industry is reduced, so as to solve the problems existing in the above background art.

[0008] The application provides the following technical scheme: a high-proportion alternative fuel pretreatment cement kiln incineration system, which comprises a stack, a storage system, a rotary kiln, a coal powder burner, a cooler, a tertiary air pipe, a raw material preheater, and further comprises a crushing system, a homogenizing system, a metering system, a conveying system, a gravity type feeding system, a multifunctional decomposition furnace, an alternative fuel special burner, and a wind conveying system; the alternative fuel is crushed to a particle size that can be suspended and lifted in a 6-10 m / s flue gas flow in the crushing system; the crushed alternative fuel is mixed and homogenized in the homogenizing system, and then is sent to the storage system; three sets of metering systems, namely a first metering system, a second metering system and a third metering system, are arranged at the discharge end of the storage system; the gravity type feeding system comprises a first gravity type feeding system and a second gravity type feeding system; the first metering system is connected with a conveying system 1, the second metering system is connected with a conveying system 2, and the third metering system is connected with a conveying system 3; the conveying system 1 is connected with the wind conveying system, and the wind conveying system is connected with the alternative fuel special burner at the kiln head; the conveying system 2 is connected with the first gravity type feeding system, and the conveying system 3 is connected with the second gravity type feeding system; the tertiary air pipe is connected with the lower cone part of the multifunctional decomposition furnace, the first gravity type feeding system and the second gravity type feeding system are respectively connected with the multifunctional decomposition furnace, the connecting port is located 2-5 m above the interface between the tertiary air pipe and the multifunctional decomposition furnace, the alternative fuel is lifted by the high-temperature mixed gas flow formed by the kiln tail flue gas and the tertiary air, and is carried upward and burned in the multifunctional decomposition furnace; the alternative fuel special burner at the kiln head is designed as an inner passage and an outer passage; the inner passage is an alternative fuel passage, the alternative fuel is sent into the rotary kiln by the air flow of the wind conveying system, and the outer passage is a rotational flow air, which surrounds the alternative fuel, so that the alternative fuel forms a certain flame shape when burning in the rotary kiln; the special burner is arranged above the coal powder burner in the rotary kiln, and the coal powder burner drives the alternative fuel to burn through the coal powder combustion.

[0009] Further, the first gravity type feeding system is composed of a first feeding chute, a first pneumatic discharge valve and a second pneumatic discharge valve; the first pneumatic discharge valve and the second pneumatic discharge valve are vertically arranged and spaced 3-6 m apart; the opening and closing time of the pneumatic discharge valve is less than or equal to 3 s; the first pneumatic discharge valve and the second pneumatic discharge valve are alternately opened and closed, one is opened while the other is closed, so as to ensure the air locking effect during discharging; the second gravity type feeding system is composed of a second feeding chute, a third pneumatic discharge valve and a fourth pneumatic discharge valve; the third pneumatic discharge valve and the fourth pneumatic discharge valve are vertically arranged and spaced 3-6 m apart; the opening and closing time of the pneumatic discharge valve is less than or equal to 3 s; the third pneumatic discharge valve and the fourth pneumatic discharge valve are alternately opened and closed, one is opened while the other is closed, so as to ensure the air locking effect during discharging.

[0010] On the basis of the foregoing scheme, a first screw conveyor is arranged between the conveying system 2 and the first gravity feeding system, and a second screw conveyor is arranged between the conveying system 3 and the second gravity feeding system, so that forced feeding is realized while a sealing effect is also increased.

[0011] As a further scheme of the present application, the first alternative fuel inlet and the second alternative fuel inlet are located on the same horizontal plane of the multifunctional decomposition furnace and are uniformly distributed along the circumference of the multifunctional decomposition furnace.

[0012] Further, the second-to-last cyclone of the preheater is connected to the multifunctional decomposition furnace, and the first raw material feeding port is located 1-4 m above the first and second alternative fuel inlets and is not on the same vertical line as the first and second alternative fuel inlets on the surface of the multifunctional decomposition furnace.

[0013] On the basis of the foregoing scheme, the second-to-last cyclone of the preheater is connected to the multifunctional decomposition furnace, and the first raw material feeding port is located 1-4 m above the first and second alternative fuel inlets and is not on the same vertical line as the first and second alternative fuel inlets on the surface of the multifunctional decomposition furnace.

[0014] As a further scheme of the present application, a length ≥ 3 m of the necked air pipe is arranged below the lower cone of the multifunctional decomposition furnace, the air flow speed in the net cross section of the air pipe is controlled to be ≥ 32 m / s, and it is ensured that the raw material and the alternative fuel do not fall into the rotary kiln.

[0015] Further, the outer passage of the special burner is composed of a plurality of rectangular holes or circular holes or square holes, the holes are uniformly distributed along the center of the special burner, and the holes jointly form a swirling air flow by spraying air flow through a swirling angle.

[0016] A method for pretreating a high-proportion alternative fuel cement kiln incineration system, comprising the following steps:

[0017] S1: The alternative fuel in the stack is sent to a crushing system for crushing, and the particle size of the crushed alternative fuel meets the following requirements: it can be suspended and lifted under the flue gas flow of 6-10 m / s in the multifunctional decomposition furnace;

[0018] S2: The crushed alternative fuel is sent to a homogenization system to realize homogenization and homogenization of the alternative fuel, and then is sent to a storage system;

[0019] S3: Three sets of metering systems are arranged at the discharge end of the storage system, the replacement fuel is sent into the rotary kiln for incineration through the first metering system, the conveying system 1 and the pneumatic conveying system, and high-temperature flue gas generated by the incineration of the replacement fuel is used for clinker calcination;

[0020] S4: The replacement fuel is sent into the multifunctional decomposing furnace through the second metering system, the conveying system 2 and the first gravity type feeding system, and through the third metering system, the conveying system 3 and the second gravity type feeding system, and is incinerated in the multifunctional decomposing furnace under the three-stage air supply oxygen environment, so as to decompose the carbonates in the raw material, and the raw material is carried to the raw material preheater along the airflow direction;

[0021] S5: Thus, the crushing, homogenization, storage, metering and conveying of the replacement fuel are realized, the replacement fuel is fed into the rotary kiln and the multifunctional decomposing furnace of the cement kiln system, the replacement fuel is burned through the multifunctional decomposing furnace and the special burner for the replacement fuel at the kiln head, the proportion of the replacement fuel heat value in the rotary kiln can reach more than 50-100%, the proportion of the replacement fuel heat value in the multifunctional decomposing furnace can reach 80-100%, and the replacement fuel heat value replacement rate of the whole cement kiln system can reach 60-100%, so that the high-proportion replacement fuel burning is realized.

[0022] Technical effects and advantages of the present application:

[0023] 1. The present application controls the crushing particle size of the replacement fuel according to the flue gas suspension speed, so that the replacement fuel realizes suspension combustion in the multifunctional decomposing furnace and moves to the outlet of the decomposing furnace along the flue gas airflow direction.

[0024] 2. The present application is metered through three metering systems, the replacement fuel is fed into the special burner in one way, the special burner and the pulverized coal burner are arranged in an upper and lower manner in the rotary kiln, and the pulverized coal combustion drives the replacement fuel combustion; two ways are symmetrically fed into the multifunctional decomposing furnace, and the replacement fuel is fed into the multifunctional decomposing furnace through the gravity type feeding system and the air locking discharge valve with two switching switches, so as to reduce the air leakage amount in the feeding process.

[0025] 3. The present application realizes forced feeding and increases an air locking device through the arrangement of the spiral conveying auger, so as to optimize the feeding system and increase the air locking effect

[0026] 4. The special burner for the replacement fuel in the present application adopts an inner and outer two-channel design, the outer channel covers the replacement fuel through the cyclone wind cage, so that the replacement fuel sprayed from the inner channel forms a certain shape, which is beneficial to control the flame shape and length and is beneficial to the clinker calcination.

[0027] 5. The present application reasonably arranges the replacement fuel inlet, the three-stage air inlet and the raw material feeding port on the multifunctional decomposing furnace, so that the replacement fuel and the raw material are better distributed and dispersed in the decomposing furnace and are carried and moved by the moving flue gas airflow, so that the replacement fuel is better burned and burned out, and the raw material is better decomposed.

[0028] 6. The alternative fuel and raw material in the present application are staggered as far as possible, and the influence of the raw material gravity falling process on the alternative fuel combustion is reduced as far as possible; the staggered arrangement of the upper and lower raw material feeding ports makes the materials not mixed during the raw material gravity falling process, which is beneficial to the raw material being lifted by the flue gas and uniformly dispersed and carried upward, and is beneficial to the temperature field control of the multifunctional decomposition furnace. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a system process block diagram of the present application.

[0030] Figure 2 is a schematic diagram of the arrangement of the pulverized coal burner and the alternative fuel special burner of the present application.

[0031] Figure 3 is a schematic diagram of the head section of the alternative fuel special burner of the present application.

[0032] Figure 4 is a schematic diagram of the head section of the alternative fuel special burner of the present application.

[0033] Figure 5 is a process flow block diagram of the present application.

[0034] Figure 6 is a schematic diagram of the alternative fuel inlet port of the present application.

[0035] Figure 7 is a schematic diagram of the raw material feeding port of the present application.

[0036] Figure 8 is a schematic diagram of the horizontal section of the alternative fuel inlet port of the present application.

[0037] 1, stack; 2, crushing system; 3, homogenizing system; 4, storage system; 5, metering system; 5-1, first metering system; 5-2, second metering system; 5-3, third metering system; 6, conveying system; 6-1, conveying system 1; 6-2, conveying system 2; 6-3, conveying system 3; 7, gravity feeding system; 7-1, first gravity feeding system; 7-1-1, first feeding chute; 7-1-2, first pneumatic discharge valve; 7-1-3, second pneumatic discharge valve; 7-1-4, alternative fuel inlet 1; 7-2, second gravity feeding system; 7-2-1, second feeding chute; 7-2-2, third pneumatic discharge valve; 7-2-3, fourth pneumatic discharge valve; 7-2-4, alternative fuel inlet 2; 8, rotary kiln; 9, cooler; 10, tertiary air pipe; 11, multifunctional decomposing furnace; 11-1, lower cone part; 11-2, necked air pipe; 12, raw material preheating device; 12-1, penultimate cyclone; 12-2-1, raw material feeding port 1; 12-2-2, raw material feeding port 2; 12-3, first discharge chute; 12-4, second discharge chute; 13, pulverized coal burner; 14, alternative fuel dedicated burner; 15, pneumatic conveying system; 16-1, first screw conveying auger; 16-2, second screw conveying auger. DETAILED DESCRIPTION

[0038] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application, and additionally, the forms of each structure described in the following embodiments are only examples, and the present application is not limited to each structure described in the following embodiments, and all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0039] Referring to FIGS. 1-8, the embodiments of the present application are described and explained.

[0040] As shown in Fig. 1, a process flow chart diagram of the present application discloses a high proportion of alternative fuel pretreatment and cement kiln incineration system, comprising a stack 1, a storage system 4, a rotary kiln 8, a cooler 9, a pulverized coal burner 13, a tertiary air pipe 10, a raw material preheater 12, characterized in further comprising: a crushing system 2, a homogenizing system 3, a metering system 5, a conveying system 6, a gravity feeding system 7, a multifunctional decomposition furnace 11, an alternative fuel dedicated burner 14, a pneumatic conveying system 15, the crushing system 2 breaks the particle size of the alternative fuel to 6-10 m / s flue gas flow that can be lifted, the particle size of the alternative fuel is determined according to the density and suspension speed, and the crushing equipment of the crushing system is selected according to the particle size; the crushed alternative fuel is sent to the homogenizing system 3 for homogenizing mixing and homogenizing, so that the physical and chemical properties of the alternative fuel are uniform, and then sent to the alternative fuel storage system 4, which can be a concrete plant, a steel plate warehouse, a concrete warehouse, etc., and has a rainproof facility to prevent the fluctuation of the moisture of the stored alternative fuel; a three-set metering system 5 is arranged at the discharge end of the storage system 4, which are respectively a first metering system 5-1, a second metering system 5-2 and a third metering system 5-3; conveying systems 6 are arranged in subsequent processes of the three-set metering system, which are respectively conveying system 1, conveying system 2 and conveying system 3, and are respectively numbered as 6-1, 6-2 and 6-3; the gravity feeding system 7 comprises a first gravity feeding system 7-1 and a second gravity feeding system 7-2; the first metering system 5-1 is connected with the conveying system 1 (6-1), the second metering system 5-2 is connected with the conveying system 2 (6-2), and the third metering system 5-3 is connected with the conveying system 3 (6-3); the conveying system 1 (6-1) is connected with the pneumatic conveying system 15, and the pneumatic conveying system 15 is connected with the alternative fuel dedicated burner 14 at the kiln head; the conveying system 2 (6-2) is connected with the first gravity feeding system 7-1, and the conveying system 3 (6-3) is connected with the second gravity feeding system 7-2; the tertiary air pipe 10 is connected with the lower cone part 11-1 of the multifunctional decomposition furnace 11, the first gravity feeding system 7-1 and the second gravity feeding system 7-2 are respectively connected with the multifunctional decomposition furnace 11, the connection port is located 2-5 m above the interface between the tertiary air pipe 10 and the multifunctional decomposition furnace 11, the alternative fuel is lifted by the high-temperature mixed gas flow formed by the kiln tail flue gas and the tertiary air, carried upward, and burned in the multifunctional decomposition furnace 11, and the combustion heat is used for raw material decomposition.

[0041] The present application burns the alternative fuel in the rotary kiln in addition to burning the alternative fuel in the multifunctional decomposition furnace 11, as shown in Figures 2, 3 and 4, the alternative fuel at the kiln head is burned by the special burner 14, the special burner 14 is arranged in the rotary kiln simultaneously with the pulverized coal burner, the special burner 14 is composed of the inner channel 14-1 and the outer channel 14-2, the inner channel 14-1 is the alternative fuel channel, the air flow of the air conveying system 15 sends the alternative fuel into the rotary kiln 8, the outer channel 14-2 is the cyclone air channel, as shown in Figures 3 and 4, the cyclone air covers the alternative fuel, so that the alternative fuel is sprayed in the rotary kiln 8 and forms a certain situation and flame shape when burned, the cyclone air can be provided as multiple round holes; as shown in Figure 2, the special burner 14 is arranged above the pulverized coal burner 13 in the rotary kiln 8, the pulverized coal burner 13 drives the alternative fuel to burn by the high-temperature combustion of the pulverized coal, the high-temperature flue gas formed after the combustion of the pulverized coal provides favorable conditions for the drying, volatilization analysis, pre-combustion and combustion of the alternative fuel, the alternative fuel is mixed with the pulverized coal for combustion in the rotary kiln, the pulverized coal burner 13 can also be designed as the burner with the natural gas or fuel oil pipeline and the injection port, so as to realize the replacement of the pulverized coal by the natural gas or fuel oil, and drive the combustion of the alternative fuel of the special burner 14 by the combustion.

[0042] In order to improve the sealing effect of feeding, as shown in Figure 6, the first gravity type feeding system 7-1 is composed of the first feeding chute 7-1-1, the first pneumatic discharge valve 7-1-2 and the second pneumatic discharge valve 7-1-3, the two pneumatic discharge valves 7-1-2 and 7-1-3 are vertically arranged along the first feeding chute 7-1-1 and are spaced apart by 3-6 m in height, the opening and closing time of the pneumatic discharge valve is ≤3 s, when the alternative fuel is fed into the multifunctional decomposition furnace 11 through the first gravity type feeding system 7-1, the two pneumatic discharge valves 7-1-2 and 7-1-3 are alternately opened and closed, one is opened at the same time, and the other is closed, so as to ensure the air locking effect during feeding; the second gravity type feeding system 7-2 is composed of the second feeding chute 7-2-1, the third pneumatic discharge valve 7-2-2 and the fourth pneumatic discharge valve 7-2-3, and is vertically arranged along the second feeding chute 7-1-1 and is spaced apart by 3-6 m in height, the opening and closing time of the pneumatic discharge valve is ≤3 s, when the alternative fuel is fed into the multifunctional decomposition furnace 11 through the second gravity type feeding system 7-2, the two pneumatic discharge valves 7-2-2 and 7-2-3 are alternately opened and closed, one is opened at the same time, and the other is closed, so as to ensure the air locking effect during feeding. In order to ensure the symmetrical feeding of the two sets of gravity type feeding systems 7-1 and 7-2, the two sets of gravity type feeding systems 7-1 and 7-2 are selected to be consistent, and are arranged symmetrically according to the center line of the multifunctional decomposition furnace 11.

[0043] In order to improve the air locking effect of the alternative fuel feeding, as shown in Fig. 5, a first screw conveyor 16-1 is arranged between the conveying system 2 (6-2) and the first gravity feeding system 7-1, and a second screw conveyor 16-2 is arranged between the conveying system 3 (6-3) and the second gravity feeding system 7-2, so that the forced feeding is realized and the sealing effect is increased.

[0044] In order to optimize the uniform feeding and homogeneous combustion effect of the alternative fuel in the multifunctional decomposing furnace 11, as shown in Figs. 6 and 8, the alternative fuel feeding port one 7-1-4 and the alternative fuel feeding port two 7-2-4 are located on the same horizontal plane of the multifunctional decomposing furnace 11 and are uniformly distributed along the circumference of the multifunctional decomposing furnace 11. Compared with the arrangement of one feeding port or two feeding ports close to each other, the alternative fuel is more dispersed and more easily uniformly distributed in the multifunctional decomposing furnace 11, and the temperature field in the multifunctional decomposing furnace 11 after the combustion of the alternative fuel is more uniform, which is helpful to control the temperature in the multifunctional decomposing furnace 11.

[0045] In order to improve the dispersion effect of the raw meal in the multifunctional decomposing furnace 11, as shown in Fig. 7, the last but one cyclone 12-1 of the raw meal preheater 12 is divided into two paths, i.e. a first path of the down spout 12-3 and a second path of the down spout 12-4, and the two paths of the down spout 12-3 and 12-4 are respectively connected with the multifunctional decomposing furnace 11 to form a raw meal feeding port one 12-2-1 and a raw meal feeding port two 12-2-2. The raw meal feeding port one 12-2-1 is 1-4 m above the level of the alternative fuel feeding port 7-1-4 and 7-2-4, the raw meal feeding port two 12-2-2 is 6-9 m above the level of the alternative fuel feeding port 7-1-4 and 7-2-4, and the raw meal feeding port one 12-2-1 and the raw meal feeding port two 12-2-2 are not located on the same vertical line on the surface of the multifunctional decomposing furnace 11, so that the two raw meal feeding ports are staggered. The raw meal feeding ports 12-2-1 and 12-2-2 are designed above the alternative fuel feeding ports, so that the alternative fuel is firstly contacted with the tertiary air for combustion, and then the temperature after the combustion is reduced by the heat absorption of the raw meal decomposition, so that the flue gas temperature in the decomposing furnace is not too high, generally at 850-1000℃, and the raw meal is prevented from forming liquid phase in the environment of too high temperature (≥1050℃), which causes the skin and material sticking on the inner surface of the multifunctional decomposing furnace 11. If the raw meal is fed into the multifunctional decomposing furnace 11, and the alternative fuel and the fuel are combusted after the raw meal is fed, the raw meal will absorb heat and reduce the temperature below the raw meal decomposition temperature, so that the fuel combustion chases the raw meal decomposition in the whole multifunctional decomposing furnace 11, the temperature in most areas of the decomposing furnace cannot reach the raw meal decomposition temperature, and even if the temperature is increased above the decomposition temperature by the fuel combustion at the outlet of the decomposing furnace, there is no raw meal decomposition space and decomposition reaction time in the decomposing furnace, which will reduce the decomposition rate of the raw meal in the multifunctional decomposing furnace 11, and further affect the calcination of the clinker in the rotary kiln 8.

[0046] To ensure that the alternative fuel can be well supported by the flue gas in the decomposition furnace, as shown in Figures 6 and 7, a length of ≥3m converging air pipe 11-2 is arranged below the lower cone 11-1 of the multifunctional decomposition furnace 11, the air flow velocity in the clear cross section of the converging air pipe 11-2 is controlled to be ≥32m / s, ensuring that the raw materials and the alternative fuel do not fall into the rotary kiln 8, especially the alternative fuel with large block size and density, the converging air velocity between the multifunctional decomposition furnace 11 and the rotary kiln 8 should be further increased, and even controlled to be 35-50m / s, far exceeding the air velocity when the pulverized coal is used as fuel in the normal decomposition furnace, so that the alternative fuel is lifted by the flue gas in the rotary kiln, burns in the multifunctional decomposition furnace 11, and is locked by the flue gas at the converging position.

[0047] To improve the effect of the swirling air flow of the outer channel 14-2 of the special burner 14, as shown in Figures 3 and 4, the outer channel is designed to be composed of a plurality of rectangular holes or circular holes or square holes, each hole is uniformly distributed along the center of the special burner 14, and each hole sprays air flow through a swirling angle to form swirling air flow together, which wraps the alternative fuel sprayed from the central pipe to form a certain state, and forms a certain flame state and flame length when burning in the rotary kiln, thereby providing favorable support for clinker calcination.

[0048] The high-proportion alternative fuel pretreatment and cement kiln incineration method has the characteristics that it comprises the following steps:

[0049] In the first step, the alternative fuel in the stack 1 is sent to the crushing system 2 for crushing, and the particle size of the crushed alternative fuel meets the following requirements: it can be suspended and lifted in the multifunctional decomposition furnace 11 under the flue gas flow of 6-10m / s, ensuring that various alternative fuels can be suspended and lifted in the multifunctional decomposition furnace 11 and will not sink and gather.

[0050] In the second step, the crushed alternative fuel is sent to the homogenizing system 3 to realize homogenization and homogenization of the alternative fuel, and then is sent to the storage system 4.

[0051] In the third step, three sets of metering systems 5 are arranged at the discharge end of the storage system 4, the alternative fuel passes through the first metering system 5-1, the conveying system 16-1, the pneumatic conveying system 15 and the special burner 14 in sequence to be sent to the rotary kiln 8 for incineration, and the alternative fuel is burned under the driving of the coal combustion in the pulverized coal burner 13 to generate high-temperature flue gas for cement clinker calcination.

[0052] Fourthly, the alternative fuel is sent into the multifunctional decomposition furnace 11 through the second metering system 5-2, the conveying system 2 (6-2) and the first gravity feeding system 7-1, and through the third metering system 5-3, the conveying system 3 (6-3) and the second gravity feeding system 7-2, and is incinerated in the multifunctional decomposition furnace 11 under the oxygen supply of the third air to generate high-temperature flue gas for the decomposition of the carbonate in the raw material, and the flue gas carries the raw material into the raw material preheater 12 along the airflow direction.

[0053] Through the above steps, the crushing, homogenization, storage, metering and conveying of the alternative fuel are realized, and the alternative fuel is uniformly and quantitatively sprayed into the rotary kiln 8 of the cement kiln system and the multifunctional decomposition furnace 11, the combustion of the alternative fuel is realized through the multifunctional decomposition furnace 11 and the special burner 14 for the alternative fuel at the kiln head, the proportion of the heat value of the alternative fuel in the rotary kiln 8 can reach 50-100% or more, all the coal powder is used as the fuel in the rotary kiln 8 at the beginning, and then the coal is gradually reduced after the clinker is stably discharged from the kiln and the high-temperature temperature field in the kiln is stable, the special burner 14 gradually sprays the alternative fuel, the proportion of the alternative fuel can be gradually increased, the proportion of the heat value of the alternative fuel in the multifunctional decomposition furnace 11 can reach 80-100%, the proportion of the heat value of the alternative fuel in the entire cement kiln system can reach 60-100%, the combustion and burnout of the alternative fuel with a high proportion are realized, and the gas-solid two-phase flow field in the entire multifunctional decomposition furnace 11 is reasonable, and the thermal system is highly consistent with the new dry process technology.

[0054] In the description in the present document, it should be noted that the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or sequence between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0055] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high proportion of alternative fuel pretreatment cement kiln incineration system, comprising a stack shelf (1), a storage system (4), a rotary kiln (8), a pulverized coal burner (13), a cooler (9), a tertiary air pipe (10), a preheated raw material preheater (12), characterized in that: Also include the crushing system (2), homogenization system (3), metering system (5), conveying system (6), gravity feeding system (7), multifunctional decomposition furnace (11), alternative fuel dedicated burner (14), wind conveying system (15), the crushing system (2) will be broken to 6-10m / s flue gas flow can be suspended particle size, the size of the broken alternative fuel into homogenization system (3) for homogeneous mixing, after homogenization, into the storage system (4), the storage system (4) discharge end is provided with three sets of metering system (5), respectively, the first metering system (5-1), the second metering system (5-2), the third metering system (5-3), gravity feeding system (7) includes the first gravity feeding system (7-1), the second gravity feeding system (7-2);The first metering system (5-1) is connected with the conveying system 1 (6-1), the second metering system (5-2) is connected with the conveying system 2 (6-2), the third metering system (5-3) is connected with the conveying system 3 (6-3);The conveying system 1 (6-1) is connected with the wind conveying system (15), the wind conveying system (15) is connected with the kiln head alternative fuel dedicated burner (14);The conveying system 2 (6-2) is connected with the first gravity feeding system (7-1), the conveying system 3 (6-3) is connected with the second gravity feeding system (7-2);The tertiary air pipe (10) is connected with the lower cone part (11-1) of the multifunctional decomposition furnace (11), the first gravity feeding system (7-1) and the second gravity feeding system (7-2) are connected with the multifunctional decomposition furnace (11) respectively, the connecting port is located 2-5m above the interface between the tertiary air pipe (10) and the multifunctional decomposition furnace (11), the alternative fuel is lifted by the high-temperature mixed gas flow formed by the kiln tail flue gas and the tertiary air, carried upward, and burned in the multifunctional decomposition furnace (11);The kiln head alternative fuel dedicated burner (14) is designed as an inner passage (14-1) and an outer passage (14-2), the inner passage (14-1) is an alternative fuel passage, the air flow of the wind conveying system (15) sends the alternative fuel into the rotary kiln (8), the outer passage (14-2) is a cyclone air, which covers the alternative fuel, so that the alternative fuel forms a certain flame shape when burning in the rotary kiln (8);The dedicated burner (14) is arranged above the coal powder burner (13) in the rotary kiln (8), and the coal powder burner (13) drives the alternative fuel to burn through the coal powder combustion zone.

2. A high proportion of alternative fuel pre-treatment cement kiln incineration system according to claim 1, characterized in that: The first gravity type feeding system (7-1) is composed of a first feeding chute (7-1-1), a first pneumatic discharge valve (7-1-2) and a second pneumatic discharge valve (7-1-3), the first pneumatic discharge valve (7-1-2) and the second pneumatic discharge valve (7-1-3) are vertically arranged and spaced 3-6 m apart, the opening and closing time of the pneumatic discharge valve is less than or equal to 3 s, the first pneumatic discharge valve (7-1-2) and the second pneumatic discharge valve (7-1-3) are alternately opened and closed, one is opened while the other is closed, so as to ensure the air locking effect during discharging; the second gravity type feeding system (7-2) is composed of a second feeding chute (7-2-1), a third pneumatic discharge valve (7-2-2) and a fourth pneumatic discharge valve (7-2-3), the third pneumatic discharge valve (7-2-2) and the fourth pneumatic discharge valve (7-2-3) are vertically arranged and spaced 3-6 m apart, the opening and closing time of the pneumatic discharge valve is less than or equal to 3 s, the third pneumatic discharge valve (7-2-2) and the fourth pneumatic discharge valve (7-2-3) are alternately opened and closed, one is opened while the other is closed, so as to ensure the air locking effect during discharging.

3. A high proportion of alternative fuel pre-treatment cement kiln incineration system according to claim 1 or 2, characterized in that: The first screw conveying auger (16-1) is arranged between the conveying system 2 (6-2) and the first gravity type feeding system (7-1), and the second screw conveying auger (16-2) is arranged between the conveying system 3 (6-3) and the second gravity type feeding system (7-2), so that forced feeding is realized and a sealing effect is also increased.

4. A high proportion of alternative fuel pre-treatment cement kiln incineration system according to claim 1 or 2, characterized in that: The first alternative fuel inlet (7-1-4) and the second alternative fuel inlet (7-2-4) are located on the same horizontal plane of the multifunctional decomposition furnace (11) and are uniformly distributed along the circumference of the multifunctional decomposition furnace (11).

5. A high percentage of alternative fuel pre-treatment cement kiln incineration system according to claim 1 or 2, characterized in that: The second-to-last cyclone of the preheating raw material preheater (12) is connected with the multifunctional decomposition furnace (11), the raw material feeding inlet one (12-2-1) is located 1-4 m above the first alternative fuel inlet (7-1-4) and the second alternative fuel inlet (7-2-4) and is not on the same vertical line with the first alternative fuel inlet (7-1-4) and the second alternative fuel inlet (7-2-4) on the surface of the multifunctional decomposition furnace (11).

6. A high percentage of alternative fuel pre-treatment cement kiln incineration system according to claim 1 or 2, characterized in that: The second-to-last cyclone of the preheating raw material preheater (12) is divided into two paths, which are the first path of the discharging chute (12-3) and the second path of the discharging chute (12-4), respectively connected with the multifunctional decomposition furnace (11) to form the raw material feeding inlet one (12-2-1) and the raw material feeding inlet two (12-2-2), the raw material feeding inlet one (12-2-1) is located 1-4 m above the first alternative fuel inlet (7-1-4) and the second alternative fuel inlet (7-2-4), the raw material feeding inlet two (12-2-2) is located 6-9 m above the first alternative fuel inlet (7-1-4) and the second alternative fuel inlet (7-2-4), and the raw material feeding inlet one (12-2-1) and the raw material feeding inlet two (12-2-2) are not on the same vertical line on the surface of the multifunctional decomposition furnace (11).

7. A high proportion of alternative fuel pre-treatment cement kiln incineration system according to claim 6, characterized in that: The lower cone part (11-1) of the multifunctional decomposition furnace (11) is provided with a length ≥3m necking air pipe (11-2) below, the air pipe net section airflow speed is controlled at ≥32m / s, which ensures that the raw materials and alternative fuels do not fall into the rotary kiln (8).

8. A high percentage of alternative fuel pre-treatment cement kiln incineration system according to claim 1, characterized in that: The outer channel (14-2) of the special burner (14) is provided with a plurality of rectangular holes or circular holes or square holes, each hole is uniformly distributed along the center of the special burner (14), and each hole sprays airflow through a swirl angle to form a swirl airflow.

9. A method of pre-treating a cement kiln incineration system for high percentage of alternative fuels based on any one of claims 1-8, characterized in that: Comprising the following steps: S1: The alternative fuel of the stack shelf (1) is sent to the crushing system (2) for crushing, and the particle size of the crushed alternative fuel meets the following requirements: it can be suspended and lifted under the 6-10m / s flue gas airflow in the multifunctional decomposition furnace (11); S2: The crushed alternative fuels are sent to the homogenizing system (3) to realize the homogenization and homogenization of the alternative fuels, and then sent to the storage system (4); S3: The storage system (4) is provided with three sets of metering systems (5) at the discharge end, the alternative fuel is sent into the rotary kiln (8) for incineration through the first metering system (5-1), the conveying system 1 (6-1) and the air conveying system (15), and the alternative fuel combustion produces high-temperature flue gas for cement clinker calcination; S4: The alternative fuel is sent into the multifunctional decomposition furnace (11) through the second metering system (5-2), the conveying system 2 (6-2) and the first gravity type feeding system (7-1), and through the third metering system (5-3), the conveying system 3 (6-3) and the second gravity type feeding system (7-2), and is incinerated in the multifunctional decomposition furnace (11) under the three times air oxygen supply environment, and is used for decomposing carbonates in raw materials and carrying raw materials to the preheating raw material preheater (12) along the airflow direction; S5: Thus, the crushing, homogenization, storage, metering and conveying of the alternative fuel are realized, the alternative fuel is fed into the rotary kiln (8) and the multifunctional decomposition furnace (11) of the cement kiln system, the combustion of the alternative fuel is realized through the multifunctional decomposition furnace (11) and the alternative fuel special burner (14) at the kiln head, the proportion of the alternative fuel heat value in the rotary kiln (8) can reach 50-100%, the proportion of the alternative fuel heat value in the multifunctional decomposition furnace (11) can reach 80-100%, and the replacement rate of the alternative fuel heat value in the whole cement kiln system can reach 60-100%, realizing the combustion of high-proportion alternative fuel.

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