WO2011009321A1 - Predecomposition kiln tail system used outside of cement kiln for processing raw materials with combustible substances - Google Patents

Abstract

A predecomposition kiln tail system used outside of a cement kiln for processing raw materials with combustible substances includes a multistage cyclone preheater (2, 3, 4, 7 and 9) and a raw material precalcination furnace (5), in which an outlet (21) for air current carrying materials is provided at the upper part of the raw material precalcination furnace (5), and an air current inlet (14) is provided at the bottom of the raw material precalcination furnace (5), and a material inlet (16) is provided at the lower part of the raw material precalcination furnace (5). The air current inlet (14) is connected with an air outlet of the cyclone preheater of stage N of the multistage cyclone preheater (2, 3, 4, 7 and 9), while the outlet (21) for air current carrying materials is connected with the cyclone preheater of stage N-1. The material inlet (16) is connected with the cyclone preheater of stage N-2 or connected directly with a feeding device.

Description

 A pre-decomposition kiln tail system capable of treating cement kiln with combustible raw materials

 The invention relates to a system for raw material preheating, raw material decomposition and fuel combustion in the cement industry, in particular to a cement kiln precalciner kiln tail system capable of treating raw materials with combustible materials. Background technique

 Cement clinker is produced by high temperature calcination of cement raw meal after preheating and decomposition. The cement raw meal is mainly formed by homogenizing the calcareous raw material, the clay raw material and the correcting raw material by grinding. At present, the production process of cement clinker generally adopts pre-decomposition technology outside the kiln. This technology is also the most advanced cement production technology today. It is characterized by: a preheating system with pre-decomposition pre-decomposition, which is mainly composed of a decomposition furnace. Multi-stage cyclone preheater and connecting air duct and material pipe. The pulverized coal is completely burned in the decomposition furnace, the raw material is fully decomposed in the decomposition furnace, and the high temperature gas of the decomposition furnace is subjected to multiple heat exchanges in the preheater system to reduce the temperature of the preheater system exhaust gas and improve the material into the furnace. The purpose of the temperature is to improve the heat exchange efficiency of the kiln tail precalcining kiln tail system. In the existing pre-decomposition kiln tail system of cement kiln, when the raw material with high combustible content is treated, the combustible material enters the secondary or first-stage preheater inlet pipe of the preheater system, and gradually heats up and is combusted with combustibles. The heat causes the primary or secondary or tertiary preheater of the system to adhere to the side wall of the equipment due to local overheating, which may cause the preheater cone or the tube to become clogged, resulting in production failure. Therefore, the current conventional kiln pre-decomposition technology is not suitable for the treatment of raw materials with high combustible content.

 In order to meet the cement production process, the raw materials required for the production of cement must meet certain requirements, especially for the raw materials used in the pre-decomposition technology of the kiln to limit the content of harmful components and combustibles.

 Cement raw material with combustibles refers to cement raw materials. Because certain materials or materials contain a certain amount of combustibles, such as residual carbon, organic matter, etc., the burnt content of cement raw materials exceeds the standard (conventional pre-decomposition outside the kiln) 5% of cement raw meal is defined as cement raw material with combustibles; carbon residue will be used in the control of raw materials. Cement raw meal is defined as conventional cement raw meal when the loss on ignition does not exceed 0.5% or does not contain combustibles. Since combustibles can oxidize and burn in high-temperature air streams and release heat, cement raw materials with combustibles cannot be used normally in conventional kiln pre-decomposition kiln systems. Raw materials with combustibles are generally not used when selecting cement raw materials. So far, there is no technical solution for large-scale treatment with combustible raw materials at home and abroad. However, with the development of society and industrial production, the problem of resource tightening has become increasingly prominent, and the demand for the development of unconventional low-grade raw materials for cement production is becoming more and more urgent. In addition, due to the general inclusion of combustibles in mine resources in some areas, the construction of cement plants in these areas must address the problem of using raw materials with combustible materials and develop new technologies for the production of cement with combustible cement raw materials. Summary of the invention

The present invention provides a water capable of treating raw materials with combustible materials in order to solve the technical problems existing in the prior art. Pre-decomposition kiln tail system outside the mud kiln, which is capable of handling cement raw materials with combustibles.

 The first technical solution adopted by the present invention to solve the technical problems existing in the prior art is: a cement kiln pre-decomposition kiln tail system capable of processing raw materials with combustible materials, including a feeding device and a multi-stage cyclone preheater a decomposing furnace, a tertiary air duct, a rotary kiln, the system further comprising a raw material pre-calcining furnace, wherein the upper part of the raw material pre-calcining furnace is provided with a gas stream outlet, a gas inlet at the bottom, and a material inlet at the bottom. The airflow inlet is connected to an air outlet of the Nth cyclone preheater in the multi-stage cyclone preheater, and the strip airflow outlet is connected to an air inlet duct of the N-1th cyclone preheater, The material inlet is connected to the discharge port of the N-2th cyclone preheater, and the feeding device is connected to the inlet pipe of the second stage cyclone preheater, wherein N represents a level of the cyclone preheater of a certain stage The number N is any natural number greater than or equal to 4 and less than or equal to 6.

 The feeding device is provided with a dispensing device.

 The raw material pre-calcining furnace is connected to the tertiary air duct through a tertiary air dividing duct.

 The raw material pre-calcining furnace comprises a column body, a lower shrinking portion is arranged below the column body, and a gas flow inlet is arranged below the lower shrinking portion, and a third air inlet and a material inlet are arranged on the side wall of the lower part of the raw material pre-calcining furnace The upper portion of the upper cylinder is provided with a strip air outlet.

 The second technical solution adopted by the present invention to solve the technical problems existing in the prior art is: a cement kiln pre-decomposition kiln tail system capable of processing raw materials with combustible materials, including a feeding device and a multi-stage cyclone preheater a decomposing furnace, a tertiary air duct, and a rotary kiln, characterized in that the system further comprises a raw material pre-calcining furnace, the upper part of the raw material pre-calcining furnace is provided with a gas flow outlet, the bottom is provided with an air flow inlet, and the lower part is provided with a material inlet, the gas inlet is connected to an air outlet of the second stage cyclone preheater, and the strip air outlet is connected to an air inlet pipe of the first stage cyclone preheater, the material inlet and the feeding device connection.

 The feeding device is provided with a dispensing device.

 The raw material pre-calcining furnace is connected to the tertiary air duct through a tertiary air dividing duct.

 The third technical solution adopted by the present invention to solve the technical problems existing in the prior art is: a cement kiln pre-decomposition kiln tail system capable of processing raw materials with combustible materials, including a feeding device and a multi-stage cyclone preheater a decomposing furnace, a tertiary air duct, and a rotary kiln, characterized in that the system further comprises a raw material pre-calcining furnace, the upper part of the raw material pre-calcining furnace is provided with a gas flow outlet, the bottom is provided with an air flow inlet, and the lower part is provided with a material inlet, the gas inlet is connected to an air outlet of the third stage cyclone preheater, and the strip air outlet is connected to an air inlet pipe of the second stage cyclone preheater, the material inlet and the feeding device Or the discharge port of the first stage cyclone preheater is connected.

 The feeding device is provided with a dispensing device.

 The raw material pre-calcining furnace is connected to the tertiary air duct through a tertiary air dividing duct.

The invention has the advantages and positive effects that: by setting a raw material pre-calcining furnace between the multi-stage preheaters, the cement clinker with combustible cement raw material can be effectively utilized, fully taking into account the exothermic characteristics of combustible combustion. And the functional zone division of each part of the preheater system combined with pre-decomposition technology realizes a new breakthrough in the treatment of the calcined cement raw material calcined cement clinker with the new dry pre-decomposition kiln tail system, thereby effectively improving the system operation rate. , expanding unconventional low The use of grade raw material resources. It solves the technical problem of system blockage caused by combustion and heat release of combustibles in raw materials that cannot be solved by conventional precalcining kiln tail system, expands the range of raw materials available for cement production, promotes rational use of resources, and realizes large mines containing combustibles. Scale and resource utilization, saving high-quality mine resources, reducing production costs, has strong operability and practicality. DRAWINGS

 1 is a schematic structural view of a single series cement kiln pre-decomposition kiln tail system to which the present invention is applied;

 2 is a schematic structural view of a double-series cement kiln pre-decomposition kiln tail system to which the present invention is applied;

 Figure 3 is a schematic view showing the structure of the raw material pre-calcining furnace of Figure 1 or Figure 2.

 In the figure: the dotted line with the arrow is the direction of the airflow, and the solid line with the arrow is the flow direction; 1. The distribution device, 2. The first stage cyclone preheater, 3. The second stage cyclone preheater, 4. The third stage Cyclone preheater, 5, raw material pre-calcining furnace, 6, gate valve, 7, fourth-stage cyclone preheater, 8, decomposition furnace, 9, fifth-stage cyclone preheater, 10, three winds and winds Pipe, 11, tertiary air duct, 12, kiln exhaust chamber, 13, rotary kiln, 14, air inlet, 15, lower shrinkage, 16, material inlet, 17, tertiary air inlet, 18, lower cylinder, 19 , the middle shrinkage section, 20, the upper cylinder, 21, the strip airflow outlet. detailed description

 In order to further understand the contents, features and effects of the present invention, the following embodiments are exemplified and described in detail with reference to the accompanying drawings:

 Example 1

 Referring to FIG. 1 and FIG. 3, a single series cement kiln external precalcining kiln tail system applying the present invention includes a feeding device (not shown), a five-stage cyclone preheater, a decomposition furnace 8, and a tertiary air duct 11 The rotary kiln 13, the raw material pre-calcining furnace 5, the upper portion of the raw material pre-calcining furnace 5 is provided with a gas flow outlet 21, the bottom is provided with an air flow inlet 14, the lower portion is provided with a material inlet 16, the air flow inlet 14 and the fourth-level cyclone The air outlet of the preheater 7 is connected, the air outlet of the strip is connected to the air inlet of the third stage cyclone preheater 4, and the material inlet is connected with the discharge port of the second stage cyclone preheater. The feeding device is provided with a raw material dispensing device 1. The raw material pre-calcining furnace 5 is connected to the tertiary air duct 11 through the tertiary air dividing duct 10. A gate valve 6 is provided on the tertiary air distribution duct 10.

 In this embodiment, the multi-stage cyclone preheater is composed of a first-stage cyclone preheater 2, a second-stage cyclone preheater 3, a third-stage cyclone preheater 4, and a fourth-stage cyclone preheater 7, The fifth stage cyclone preheater 8 constitutes a five-stage cyclone preheater. However, it is not limited thereto, and the number of preheater stages may be six, four, three or two. The decomposition furnace 8 may be of a squirt type, a pipe type, a swirl type, a fluidized type or a plurality of combinations.

In the present embodiment, the raw material pre-calcining furnace 5 is connected between the fourth-stage preheater and the third-stage preheater, but is not limited to the connection position, and the raw material pre-calcining furnace 5 can also be connected in the same manner. In the system between the fourth stage cyclone preheater and the fifth stage cyclone preheater; when the number of preheater stages is six, the raw material precalciner can also be used in the same way Connected between the fifth stage cyclone preheater and the sixth stage cyclone preheater in the system. The specific position of the raw material precalciner varies depending on factors such as the composition, content, and ignition temperature of the combustibles in the raw meal.

 The key of the present invention is: the pre-decomposition kiln tail system is based on the existing conventional dry pre-decomposition kiln tail system, and then a raw material pre-calcining furnace 5 is added, and the tertiary air portion is introduced into the raw material pre-calcining furnace. 5. Thus, a raw material precalciner 5, a decomposition furnace 8 and a multistage cyclone preheater constitute a cement kiln precalciner kiln tail system capable of treating raw materials with combustible materials. The feeding device of the pre-decomposition kiln tail system is provided with a material distributing device 1. The invention adopts the prior art feeding device 1 to make the raw material feeding mode more flexible, and to process the cement raw material with combustible materials. When the raw material can be fed into the inlet duct of the second stage cyclone preheater 3, the four-stage preheater heat exchange is realized. The uppermost first stage cyclone preheater 2. The second stage cyclone preheater 3 is connected in series to form a cyclone dust collection system for intensive dust collection of raw materials with combustibles. When processing the conventional cement raw material, the raw material can be fed into the air inlet pipe of the first stage cyclone preheater 2, thereby realizing the heat exchange of the five-stage preheater, thereby reducing the exhaust gas temperature of the preheater system, thereby effectively reducing System heat consumption. The raw material pre-calcining furnace 5 can supplement the introduction of the tertiary air to supplement the oxygen required for combustion of the combustibles, and control the flow of the tertiary air by adding a door valve 6 to the tertiary air dividing duct 10. Depending on the composition and content of combustibles in the raw meal, the raw pre-calciner can also be used without the need to supplement the tertiary air. The pre-decomposition kiln tail system can effectively utilize the calcined cement clinker with combustible cement raw meal. The pre-decomposition kiln tail system fully considers the exothermic characteristics of combustible combustion, and combines the functional zones of various parts of the preheater system with pre-decomposition technology to realize the new dry pre-decomposition kiln tail system to fully utilize the combustible content. A new breakthrough in high raw material calcined cement clinker, thereby effectively increasing the system operation rate and expanding the utilization of unconventional low-grade raw material resources.

 Referring to FIG. 3, the raw material pre-calcining furnace 5 in the present embodiment, the raw material pre-calcining furnace 5 is a combustible material burning device, including an upper column body 20 and a lower column body 18 connected through the intermediate neck portion 19. Or a cylinder having no central constriction, a lower constricted portion 15 is disposed under the cylinder, and an airflow inlet 14 communicating with the air outlet of the fourth-stage cyclone preheater 7 is disposed below the lower constricted portion 15 The lower side wall of the calciner 5 is provided with a tertiary air inlet 17 connected to the tertiary air distribution duct 10 and a material inlet 16 connected to the discharge opening of the second stage cyclone preheater 3, and the upper part of the upper cylinder 20 is disposed. There is a strip gas outlet 21 connected to the inlet duct of the third stage cyclone preheater 4.

 The working principle of the above raw material precalcining furnace 5:

 The raw meal enters the raw material pre-calcining furnace 5 from the material inlet 16 and is in contact with the incoming gas stream, and the temperature rapidly rises to the ignition point of most of the combustibles. The inlet gas stream has a small amount of oxygen, which can cause the combustion of combustibles. When the oxygen content in the furnace gas flow is insufficient to ensure the combustion of the combustibles, the tertiary air can be introduced from the tertiary air inlet 17, and the tertiary air is the kiln. The high temperature gas extracted by the head cooler has an oxygen content close to that of air, about 21%. When the airflow passes through the central constricted portion 19, a recirculation zone, that is, a spurt effect, prolongs the solid-gas residence time ratio, which is beneficial to the complete combustion of the combustible in the pre-calciner. If the raw material pre-calciner has no central shrinkage, it is also possible to ensure complete combustion of the combustibles in the pre-calciner by appropriately increasing the volume of the raw material pre-calciner. The completely burnt raw meal is discharged from the strip gas outlet 21 along with the gas stream, and enters the third stage cyclone preheater 4 for gas-solid separation. The precalciner 5 serves the purpose of completely calcining the combustibles in the raw meal.

As is known to those skilled in the art, the above raw pre-calciner 5 is of the squirt type. Raw material pre-calcining furnace 5 can also It will be apparent to those skilled in the art that a pipe type, a swirl type, a fluidized type or a plurality of combinations are used, and will not be described herein.

 The working principle of this embodiment:

 The cement raw material with combustible material is ground and homogenized and transported to the kiln tail by lifting equipment. The material distributing device 1 can flexibly control the cement raw material with combustible materials to enter the position of the pre-decomposition kiln tail system. When processing the cement raw material with combustible material, the raw material is fed into the inlet air duct of the second-stage cyclone preheater 3 to realize the heat exchange of the four-stage preheater; when processing the conventional cement raw material, the raw material can be fed The inlet air duct of the first stage cyclone preheater 2 realizes the heat exchange of the five-stage preheater.

 When processing cement raw materials with combustibles, the cement raw material with combustibles enters the inlet duct of the second stage cyclone preheater 3, is fully dispersed, and exchanges heat with the exhaust gas to achieve preheating and then dusting. The airflow enters the second-stage cyclone preheater 3 for gas-solid separation, and the separated material is fed into the raw material pre-calcining furnace 5, and the separated airflow enters the first-stage cyclone preheater 2 to re-enforce separation and dust removal. Raw material pre-calcining furnace 5 The internal gas temperature is between 700 °C and 900 °C, and the combustibles in the raw material are rapidly burned at this temperature. The oxygen required for combustion is mainly supplied by the excess air in the exhaust gas of the fourth stage cyclone preheater 7, and can also be supplemented by introducing a portion of the tertiary air into the raw material precalciner 5 on the tertiary duct 11. The tertiary air duct 10 of the raw material pre-calcining furnace is provided with a gate valve 6 to adjust the tertiary air flow into the raw material pre-calcining furnace to ensure complete combustion of the combustibles in the raw material pre-calcining furnace. After the combustibles in the raw material are completely burned in the raw material pre-calcining furnace, the third-stage cyclone preheater 4, the fourth-stage cyclone preheater 7, the decomposition furnace 8, and the fifth-stage cyclone preheater 9 are sequentially passed through. After the kiln exhaust chamber 12 is burned into the rotary kiln 13 to obtain cement clinker.

 When processing the conventional cement raw meal, the raw material enters the inlet duct of the first stage cyclone preheater 2, which is similar to the conventional kiln tail precalcining kiln tail system working process, and the raw material passes through the first stage cyclone preheater. 2, the second stage cyclone preheater 3 performs gas-solid separation, and the separated material is fed into the raw material pre-calcining furnace 5, at which time the raw material pre-calcining furnace 5 only serves as a heat exchange function for connecting the air duct.

 Example 2:

 A cement kiln pre-decomposition kiln tail system capable of treating raw materials with combustible materials, the raw material pre-calcining furnace gas inlet is connected with the outlet of the second-stage cyclone preheater, and the raw material pre-calcining furnace has a gas outlet and The inlet pipe of the first stage cyclone preheater is connected, and the material inlet of the raw material precalciner is connected with the feeding device. When processing the cement raw material with combustibles, the raw material is directly fed into the raw material pre-calcining furnace, and exchanges heat with the gas stream from the second-stage cyclone preheater, and the combustibles in the raw material are fully combusted, and then enter the first stage. The cyclone preheater is then treated with the same structure as the conventional kiln tail system. The other structure is the same as that of Embodiment 1, and the working principle is the same as that of the embodiment.

 Example 3:

A cement kiln pre-decomposition kiln tail system capable of treating raw materials with combustible materials, the raw material pre-calcining furnace gas inlet is connected with the outlet of the third-stage cyclone preheater, and the raw material pre-calcining furnace has a gas outlet and The inlet duct of the second stage cyclone preheater is connected, and the feeding device is connected with the material inlet of the raw material precalciner or the inlet duct of the first stage cyclone preheater. When the feeding device is connected with the material inlet of the raw material pre-calcining furnace, the feeding device directly feeds the cement raw material with combustible materials into the raw material pre-calcining furnace, and the combustible material in the raw material is fully combusted and enters the second stage. The cyclone preheater performs gas-solid separation. The other structure is the same as that of the first embodiment, and the working principle is the same as the embodiment. Feeding device and the first cyclone preheater When the air duct is connected, the cement raw material with combustible material is separated by the first-stage heat exchange and gas-solid separation, and the material of the first-stage cyclone preheater enters the raw material pre-calcining furnace, so that the combustible material in the raw material is fully combusted. The other structure is the same as that of the first embodiment, and the working principle is the same as the embodiment.

 Referring to Fig. 2, the double series cement kiln tail precalcining kiln tail system of the present invention is applied, and will not be described here.

 The principle of the invention is that the cement raw material with combustibles enters the raw material pre-calcining furnace before the system may cause blockage, and the combustibles in the raw material are completely burned in the raw material pre-calcining furnace, thereby avoiding combustibles in the system. Other parts of the local combustion heat release caused by the blockage. At the same time, after the raw material with combustibles enters the system, the dust collection efficiency of the system may be drastically reduced. The technical consideration of the present invention can be treated by means of a secondary preheater in series with dust collection.

 Although the preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative and not restrictive. In the light of the present invention, many forms may be made without departing from the scope of the invention and the scope of the invention, which is within the scope of the invention.

Claims

Claim 1. A cement kiln precalciner kiln tail system capable of treating raw materials with combustible materials, comprising a feeding device, a multi-stage cyclone preheater, a decomposition furnace, a tertiary air duct, and a rotary kiln, wherein the system further The invention comprises a raw material pre-calcining furnace, wherein an upper part of the raw material pre-calcining furnace is provided with a gas stream outlet, a bottom is provided with an air flow inlet, a lower part is provided with a material inlet, and the air flow inlet is in the multi-stage cyclone preheater An air outlet of the Nth cyclone preheater is connected, and the strip air outlet is connected to an air inlet pipe of the N-1th cyclone preheater, and the material inlet is under the N-2 grade cyclone preheater The feed port is connected to the inlet pipe of the second stage cyclone preheater, wherein N represents the number of stages of a certain stage cyclone preheater, and N is any natural number greater than or equal to 4 and less than or equal to 6. .  2. The cement kiln pre-decomposition kiln tail system capable of processing a raw material with combustible material according to claim 1, wherein: the feeding device is provided with a material distributing device.  3. The cement kiln precalciner kiln tail system capable of processing a raw material with combustible material according to claim 1 or 2, wherein: the raw material precalcining furnace and the tertiary air duct pass three winds and winds Pipe connection.  4. The cement kiln pre-decomposition kiln tail system capable of processing a raw material with combustible material according to claim 1, wherein: the raw material pre-calcining furnace comprises a column body, and the column body is provided with a downward contraction. An airflow inlet is disposed under the mouth portion, and a lower air inlet and a material inlet are disposed on a sidewall of the lower portion of the raw material pre-calcining furnace, and a gas flow outlet is disposed at an upper portion of the upper cylinder.  5. A cement kiln pre-decomposition kiln tail system capable of treating raw materials with combustible materials, comprising a feeding device, a multi-stage cyclone preheater, a decomposition furnace, a tertiary air duct, and a rotary kiln, wherein the system further The utility model comprises a raw material pre-calcining furnace, wherein an upper part of the raw material pre-calcining furnace is provided with a gas flow outlet, a bottom is provided with an air flow inlet, a lower part is provided with a material inlet, and the air flow inlet and the air outlet of the second-stage cyclone preheater Connected, the strip gas outlet is connected to the inlet duct of the first stage cyclone preheater, and the material inlet is connected to the feeding device.  6. The cement kiln pre-decomposition kiln tail system capable of processing a raw material with combustibles according to claim 5, wherein: the feeding device is provided with a dispensing device.  The cement kiln pre-calcining kiln tail system capable of processing raw materials with combustible materials according to claim 5 or 6, wherein: the raw material pre-calcining furnace and the tertiary air duct pass three winds and winds Pipe connection.  8. A cement kiln precalciner kiln tail system capable of treating raw materials with combustible materials, comprising a feeding device, a multi-stage cyclone preheater, a decomposition furnace, a tertiary air duct, and a rotary kiln, wherein the system further The utility model comprises a raw material pre-calcining furnace, wherein an upper part of the raw material pre-calcining furnace is provided with a gas flow outlet, a bottom is provided with an air flow inlet, a lower part is provided with a material inlet, and the air flow inlet and the air outlet of the third-stage cyclone preheater Connected, the strip gas outlet is connected to the inlet duct of the second stage cyclone preheater, and the material inlet is connected to the feeding device or the discharge port of the first stage cyclone preheater.  9. The cement kiln pre-decomposition kiln tail system capable of processing a raw material with combustible material according to claim 8, wherein: the feeding device is provided with a material distributing device.  The cement kiln external precalcining kiln tail system capable of processing raw materials with combustible materials according to claim 8 or 9, wherein: the raw material precalcining furnace and the tertiary air duct pass three winds and winds Pipe connection.