Cement decomposing furnace combustion system based on pulverized coal preheating gasification and working method thereof
By using coal powder preheating gasification and hierarchical air supply technology in the cement decomposition furnace, the burner layout is optimized, and the problems of low combustion efficiency and NOx emission exceeding the standard in traditional cement decomposition furnaces are solved, and efficient and stable combustion process and low pollution emissions are achieved.
Patent Information
- Application Number
- CN202510597877.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-08-01
AI Technical Summary
The burner layout design and direct combustion process of traditional cement decomposition furnaces have problems such as low combustion efficiency, difficulty in temperature control, and excessive nitrogen oxide (NOx) emissions. Especially when dealing with inferior coal powder, the combustion is incomplete and the gasification reaction is low, resulting in serious energy consumption and environmental pollution.
The cement decomposition furnace combustion system based on preheating and gasification of coal powder is adopted. By setting up multiple sets of hedging burners and airflow bed gasification furnaces in the decomposition furnace body, the burner arrangement is optimized, and combined with the graded air supply technology, a strong cyclone field and a reducing atmosphere is formed, which promotes full combustion of fuel and reduces NOx generation.
The combustion efficiency has been improved, the coal powder combustion rate has increased from 82% to more than 95%, and the NOx emissions have been reduced to below 35.65mg/Nm3, which has enhanced the stability and uniformity of combustion and reduced energy consumption and pollutant emissions.
Smart Images
Figure CN120403259A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of cement production, and relates to a combustion system for a cement precalciner based on pulverized coal preheating and gasification and a working method thereof. Background Art
[0002] The cement precalciner is one of the crucial equipment in the cement production process. Its core function is to decompose calcium carbonate in limestone under high-temperature conditions. Inside the precalciner, as the temperature rises sharply, the molecular structure of calcium carbonate gradually changes, chemical bonds break and recombine, and finally quicklime is generated while releasing carbon dioxide at the same time. This process is an extremely important chemical reaction in the early stage of cement production, laying a solid foundation for the subsequent calcination of cement clinker and directly affecting the quality and output of cement products.
[0003] However, there are many technical problems in the burner layout design and direct pulverized coal combustion process of traditional cement precalciners, mainly manifested as low combustion efficiency, difficult temperature control, and excessive emissions of nitrogen oxides (NOx). These problems are particularly prominent when using low-calorific-value and low-quality coal, resulting in incomplete combustion, low gasification reaction efficiency, further aggravating energy consumption and emission pollution. Especially when dealing with low-quality pulverized coal, traditional gasifiers often encounter problems such as difficult ignition and incomplete gasification, thus unable to effectively optimize the gasification process of coal. These technical bottlenecks not only significantly reduce the overall efficiency of cement production but also have a serious impact on the environment.
[0004] Therefore, how to optimize the combustion layout of the cement precalciner, improve the combustion efficiency, and reduce the emissions of harmful gases such as NOx has become a technical problem that the current cement industry urgently needs to overcome. Summary of the Invention
[0005] The purpose of the present invention is to provide a combustion system for a cement precalciner based on pulverized coal preheating and gasification and a working method thereof to solve the technical problems of low pulverized coal combustion efficiency and excessive emissions of nitrogen oxides (NOx) in the prior art.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] In a first aspect, the present invention provides a combustion system for a cement precalciner based on pulverized coal preheating and gasification, including a precalciner furnace body, a rotary kiln, and a grate cooler connected in sequence; the combustion chamber of the precalciner furnace body is located in the middle of the precalciner furnace body, and a plurality of groups of precalciner burners are circumferentially arranged in the middle of the precalciner furnace body; each group of precalciner burners is connected to a entrained flow gasifier; an ignition burner is arranged at one end of the entrained flow gasifier, and a plurality of gasifier burners are circumferentially arranged on the entrained flow gasifier.
[0008] Further, four groups of the calciner burners are circumferentially arranged in the middle of the calciner body; two calciner burners are axially arranged in each group along the calciner body, for a total of eight calciner burners, which are arranged in a pairwise counter-jet manner along the radial direction of the calciner body.
[0009] Further, each of the gasifier burners is sequentially connected to a screw coal feeder and a first blower, which are used to convey cold pulverized coal into the entrained flow gasifier.
[0010] Further, a safety valve is arranged on the connecting pipeline between the gasifier burner and the screw coal feeder.
[0011] Further, one end of the ignition burner is connected to a gas source; one side of the ignition burner is connected to a second blower.
[0012] Further, a secondary air duct and a first raw material inlet are arranged on the outer wall of the calciner body above the combustion chamber.
[0013] Further, a second raw material inlet and a tertiary air duct are arranged on the outer wall of the calciner body corresponding to the position of the combustion chamber; both the second raw material inlet and the tertiary air duct are located below the calciner burner.
[0014] Further, the pipe diameter of the calciner burner is not less than 200 mm.
[0015] In a second aspect, the present invention provides a working method of the cement calciner combustion system based on pulverized coal preheating gasification, including the following steps:
[0016] Cold pulverized coal is sprayed into the entrained flow gasifier through the gasifier burner and burns into gasified fuel in the entrained flow gasifier.
[0017] The gasified fuel is sprayed into the combustion chamber of the calciner body in a counter-jet manner through the calciner burner, undergoes full combustion to participate in cement decomposition, and cement raw meal is obtained.
[0018] The cement raw meal enters the rotary kiln for calcination to obtain cement clinker, and is cooled and collected by a grate cooler.
[0019] Further, a secondary air duct is arranged on the outer wall of the calciner body above the combustion chamber for supplementary air supply, and the air volume of the supplementary air supply accounts for 12% - 18% of the total air volume.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The present invention discloses a combustion system and its working method for a cement precalciner based on pulverized coal preheating gasification. By arranging 8 opposed burners, the uniformity of the temperature field in the furnace is increased by 40%, and the burnout rate of pulverized coal is increased from 82% to over 95%. The burner pipe diameter is increased, the velocity of the gasification products is reduced, and the residence time of the fuel in the reduction section is increased. By optimizing the flow rate ratio, a strong swirling flow field is formed in the furnace to uniformly increase the furnace temperature; the opposed burners form four groups of symmetric eddy pairs on the furnace cross-section, and secondary air replenishment points are arranged on the upper part of the corresponding combustion chamber of the furnace body. Through CFD simulation and flow field optimization, the efficient combustion state of the fuel is maintained to ensure the continuous and stable operation of the system.
[0022] Furthermore, in the gasifier, the conversion of fuel N to N2 is promoted, and the NOx emissions after combustion are reduced. Since the amount of oxygen supplied to the gasifier is severely insufficient compared to the oxygen required for the complete combustion of pulverized coal, the atmosphere in the furnace is a strong reducing atmosphere. The strong reduction zone formed by the gasification products in the precalciner, where the gasification product reduction zone wraps the combustion zone, enhances the reduction effect in the reduction section of the precalciner. After the gasified fuel is mixed with the oxygen in the secondary air, the specific heat capacity of the flue gas generated by combustion is higher. When the same amount of heat is released by combustion, the maximum combustion temperature is reduced, which is beneficial to reducing NOx emissions after combustion. This way of staged combustion combined with low oxygen concentration operation reduces the NO x generation amount to 35.65 mg / Nm 3 or less.
[0023] Furthermore, the gasifier changes the ignition and combustion of "cold pulverized coal" into the ignition and combustion of high-temperature "gasified fuel". The internal microporous structure of the high-temperature semicoke is developed, and the combustion reactivity is greatly improved. Moreover, the temperature of the gasified fuel is higher than its ignition point, and it can directly ignite and stably burn when it comes into contact with air. It can achieve stable gasification of inferior coal with ash content ≥ 35% and volatile matter ≤ 15%, and the carbon conversion rate ≥ 92%, realizing the synergistic optimization of fuel self-preheating and rapid burnout. The system of the present invention has strong flexibility and stability, and a wide fuel adaptation range. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0025] Figure 1 It is a schematic diagram of the layout method of a combustion system for a cement precalciner based on pulverized coal preheating gasification according to an embodiment of the present invention;
[0026] Figure 2 It is a top view of the main body of the precalciner according to an embodiment of the present invention;
[0027] Figure 3 This is the comparison chart of the NOx concentration at the outlet of the precalciner under the three working conditions of direct combustion, gasification, and gasification-optimization in the embodiments of the present invention;
[0028] Figure 4 This is the comparison chart of the maximum temperature of the precalciner under the three working conditions of direct combustion, gasification, and gasification-optimization in the embodiments of the present invention;
[0029] Figure 5 This is the comparison chart of the CaCO3 decomposition rate under the three working conditions of direct combustion, gasification, and gasification-optimization in the embodiments of the present invention.
[0030] Wherein: 1 - precalciner furnace body; 2 - secondary air duct; 31 - first raw material inlet; 32 - second raw material inlet; 4 - entrained flow gasifier; 5 - ignition burner; 6 - gasifier burner; 7 - precalciner burner; 8 - tertiary air duct; 9 - screw feeder; 101 - first fan; 102 - second fan; 11 - gas source; 12 - safety valve; 13 - grate cooler; 14 - rotary kiln. Detailed implementation manners
[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.
[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0033] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0034] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.
[0035] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.
[0036] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they 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 or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.
[0037] The following further describes the present invention in detail with reference to the drawings:
[0038] See Figure 1 And Figure 2 , the embodiments of the present invention disclose a cement precalciner combustion system based on pulverized coal preheating gasification, including a precalciner furnace body 1, a rotary kiln 14, and a grate cooler 13 connected in sequence; the combustion chamber of the precalciner furnace body 1 is located in the middle of the precalciner furnace body 1, and several groups of precalciner burners 7 are circumferentially arranged in the middle of the precalciner furnace body 1; each group of precalciner burners 7 is connected to a entrained flow gasifier 4; an ignition burner 5 is arranged at one end of the entrained flow gasifier 4, and several gasifier burners 5 are circumferentially arranged on the entrained flow gasifier 4. In this embodiment, the entrained flow gasifier 4 is used to realize the preheating gasification of pulverized coal to generate gasified fuel. These gasified fuels enter the precalciner furnace body 1 for combustion. This method not only improves the combustion efficiency of pulverized coal, but also can better control the combustion process and make the combustion more stable.
[0039] In a feasible embodiment of the present invention, four groups of the calciner burners 7 are circumferentially arranged in the middle of the calciner body 1; two calciner burners 7 are axially arranged in each group along the calciner body 1, with a total of eight calciner burners 7, which are arranged in a two-by-two counter-jet manner along the radial direction of the calciner body 1. Four gasifier burners 6 are symmetrically arranged in the circumferential direction of the entrained flow gasifier 4. The pipe diameter of the calciner burner 7 is not less than 200 mm. In this embodiment, by using the advantages of strong gas-solid mixing and fast heat and mass transfer rate of the multi-nozzle counter-jet entrained flow gasifier 4, the pulverized coal is rapidly semi-gasified in the gasifier, and through the coupling of the counter-jet entrained flow gasifier 4 and the cement calciner burner, the combustion reactivity in the furnace is greatly improved. By optimizing the burner arrangement method, the original four burners of the calciner are changed to eight counter-jet arranged burners, and the burner pipe diameter is increased to reduce the velocity of the gasification products and increase the residence time of the fuel in the reduction section. The distribution of the burners is made more uniform, and the furnace temperature is evenly increased.
[0040] In a feasible embodiment of the present invention, each gasifier burner 5 is sequentially connected with a screw feeder 9 and a first blower 101 for transporting cold pulverized coal into the entrained flow gasifier 4. A safety valve 12 is also provided on the connecting pipeline between the gasifier burner 5 and the screw feeder 9. One end of the ignition burner 5 is connected to a gas source 11; one side of the ignition burner 5 is connected to a second blower 102. The combustion-supporting air entering the entrained flow gasifier 4 is defined as primary air and is evenly distributed into four conveying pipelines. The total amount of primary air is controlled in the range of 20%-45% of the theoretical air volume required for complete combustion of the pulverized coal. The normal-temperature pulverized coal output by the four screw feeders 9 is sent into the entrained flow gasifier 4 in a counter-jet manner by the four-way primary air respectively. Under the condition of controlling the oxygen supply, the pulverized coal undergoes pyrolysis, partial combustion and gasification reactions synchronously in the furnace. The generated heat energy partially maintains the self-sustaining operation of the system, and partially heats the material to form a stable gas-solid mixed fuel at 700-900°C. The gasification products include two types of components: the solid phase is high-temperature semicoke with significantly improved reaction activity, and the gas phase is combustible gas mainly composed of N2, CO, H2, CH4 and CO2. After mixing, they are collectively referred to as gasification fuel. By adjusting the input ratio of fuel and air, the temperature distribution in the furnace is precisely controlled, effectively preventing coking on the furnace wall and blockage at the outlet.
[0041] In a feasible embodiment of the present invention, a secondary air duct 2 and a first raw meal inlet 31 are provided on the outer wall of the precalciner body 1 above the combustion chamber. The air volume supplemented by the secondary air duct 2 accounts for 12% - 18% of the total air volume. A second raw meal inlet 32 and a tertiary air duct 8 are provided on the outer wall of the precalciner body 1 corresponding to the position of the combustion chamber; both the second raw meal inlet 32 and the tertiary air duct 8 are located below the precalciner burner 7, and the air source of the tertiary air duct 8 is the hot air generated in the rotary kiln 14. This embodiment adopts the staged air supply technology to send the air required for combustion in stages, taking into account both combustion efficiency and pollutant control.
[0042] The embodiment of the present invention discloses a working method of the cement precalciner combustion system based on pulverized coal preheating and gasification, including the following steps:
[0043] Cold pulverized coal is sprayed into the entrained flow gasifier 4 through the gasifier burner 6 and burns into gasified fuel in the entrained flow gasifier 4;
[0044] The gasified fuel is sprayed into the combustion chamber of the precalciner body 1 in a counter-jet manner through the precalciner burner for full combustion to participate in cement decomposition, obtaining cement raw meal;
[0045] The cement raw meal enters the rotary kiln 14 for calcination to obtain cement clinker, and is cooled and collected by the grate cooler 13.
[0046] The working principle of the present invention is as follows:
[0047] The system of the present invention mainly includes a pulverized coal entrained flow preheating and gasification unit, a cement kiln unit, and pipelines and conveying equipment connecting each component. The pulverized coal entrained flow preheating and gasification unit includes an entrained flow gasifier 4, an ignition burner 5, a gasifier burner 6, a screw feeder 9, a fan, a gas source 11, a safety valve 12, etc. The cement kiln unit includes a precalciner body 1, a precalciner burner 7 (8 counter-jets), a secondary air duct 2, a tertiary air duct 8, a rotary kiln 14, a grate cooler 13, an induced draft fan, etc.
[0048] The pulverized coal entrained flow preheating and gasification unit is mainly used to burn the "cold pulverized coal" into high-temperature "gasified fuel" for combustion. The air supplied to each gasifier is evenly divided into four streams, and the normal-temperature "cold pulverized coal" sent by the four screw feeders 9 is carried by the four primary air streams and sprayed into the entrained flow gasifier 4 in a counter-jet manner.
[0049] Under the condition of insufficient oxygen supply, the "cold pulverized coal" undergoes pyrolysis, partial combustion, and gasification simultaneously in the entrained flow gasifier 4. Part of the released heat is used for the continuous and stable operation of the entrained flow gasifier 4, and the other part is used to heat the "cold pulverized coal" to obtain the "hot gas-solid mixed fuel" at 700°C - 900°C. The solid-phase product after the pulverized coal is gasified in the gasifier is "high-temperature semicoke", and its ignition performance and reactivity are greatly improved; the main components of the gas-phase product are N2, CO, H2, CH4, and CO2, which is called "gasified gas" and is extremely easy to ignite. The mixture of the high-temperature semicoke and the gasified gas after gasification is defined as "gasified fuel". By controlling the fuel supply amount and air supply amount into the gasifier, the temperature inside the gasifier and the outlet temperature of the gasifier are controlled to avoid coking on the gasifier wall and blockage at the outlet.
[0050] The gasified fuel is sprayed into the combustion chamber through the connecting pipeline between the gasifier and the combustion chamber and is completely burned through the calciner burner 7. Since the temperature of the gasified fuel entering the combustion chamber is much higher than its ignition temperature and is rich in combustible gases, the gasified fuel can immediately catch fire when it encounters oxygen in the air. At the same time, by optimizing the layout of the calciner burner 7, the previous combustion chamber is raised from the bottom cone of the calciner body 1 to the middle of the calciner body 1, the conical burner is cancelled, and the burners are distributed in groups of 4 along the reduction section of the calciner to form a total of 8 pairs of opposed burners in the upper and lower layers, increasing the burner diameter, reducing the velocity of the gasification products, and increasing the residence time of the fuel in the reduction section to avoid premature burnout of the gasification products.
[0051] The air required for the complete combustion of the gasified fuel is fed into the calciner body 1 by the air staging method, and the high-efficiency combustion of the gasified fuel and the integration of low NOx emissions are achieved by reasonably distributing the air volume. After combustion, the gasified gas of the gasified fuel is rich in easily ignitable CO, H2, and CH4, the internal microporous structure of the high-temperature semicoke is developed, the combustion reactivity is greatly improved, and the temperature of the gasified fuel is higher than its ignition point, so it can directly catch fire when it comes into contact with air and burn stably.
[0052] Compare the NOx concentration at the outlet of the calciner and the highest temperature of the calciner under the three working conditions of direct combustion, gasification, and gasification-optimization of the present invention, respectively, as Figure 3 and Figure 4 shown. The comparison of the CaCO3 decomposition rates under the three working conditions is as Figure 5 shown. It can be seen that the fuel combustion rate of the system of the present invention is high, the NOx emission is low, and the CaCO3 decomposition rate is the highest.
[0053] Example 1:
[0054] On a cement production line with a clinker output of 5000 t / d and a pulverized coal throughput of 35 t / h, the system and method provided by the present invention are applied. Preferably:
[0055] The designed entrained flow gasifier 4 is a four-channel opposed type pulverized coal gasification device. The primary air volume is set at 30% of the theoretical combustion air volume of the pulverized coal. Four screw coal feeders 9 inject normal temperature pulverized coal into the furnace through the opposed nozzles at a flow rate of 12 m / s.
[0056] The designed operating temperature of the entrained flow gasifier 4 is maintained at 800 ± 50 °C, enabling the pyrolysis of pulverized coal to generate combustible gas containing 25% CO and 18% H2 and highly reactive semi-coke with a porosity of 65%. The calorific value of the gasified fuel reaches 3800 - 4200 kcal / kg.
[0057] The designed decomposition furnace combustion chamber is provided with 8 opposed decomposition furnace burners 7 with a diameter of Φ220 mm (4 in each of the upper and lower double layers). The spacing of the decomposition furnace burners 7 is 2.4 m, and the fuel flow rate is controlled at 8 m / s, extending the residence time of the gasified fuel in the reduction section to 3.2 s.
[0058] The air make-up of the secondary air duct 2 is extended to 3 places. The tertiary secondary air system is supplemented at 1.8 m, 3.6 m, and 5.4 m above the burner, and the proportions of the supplemented air volume are 15%, 20%, and 25% respectively, constructing a gradient oxygen concentration field (8% → 12% → 18%).
[0059] Preferably: During the operation of the system, the burnout rate of pulverized coal is increased to 95.6%, and the NOx emission is stabilized at 35 mg / Nm 3 Below, it saves 18% energy compared with the traditional process, and the temperature difference between the gasifier outlet and the decomposition furnace cross-section is controlled within ±30 °C.
[0060] Example 2:
[0061] On a cement production line with a clinker output of 7200 t / d and a pulverized coal treatment volume of 50 t / h, the system and method provided by the present invention are applied. Preferably:
[0062] The designed entrained flow gasifier 4 and the decomposition furnace body 1 are directly connected by an adiabatic pipeline with a diameter of Φ300 mm. The pipeline is lined with a silicon carbide ceramic layer, and the gasified fuel is transported at a low speed of 5 m / s, with the overall temperature drop less than 50 °C.
[0063] The reduction section of the designed decomposition furnace body 1 is arranged with a regular octagon burner array. 8 decomposition furnace burners 7 with a diameter of Φ250 mm are symmetrically distributed at 45°, forming a stable vortex area with a diameter of 2.1 m in the center of the furnace.
[0064] The designed variable-diameter multi-channel decomposition furnace burner 7: The central Φ80 mm channel transports the gasified gas, the annular gap Φ200 mm channel transports the semi-coke, and the outer ring Φ300 mm channel introduces the tertiary air to achieve the stratified mixing of multi-phase fuels.
[0065] Preferably, when the system processes high-ash coal (ash content > 38%), the temperature of the waste gas at the kiln tail is stabilized at 1050 - 1100 °C, and the dioxin emission is < 0.05 ng-TEQ / m 3 , and the specific heat consumption of the clinker is reduced by 22%.
[0066] Example 3:
[0067] On a cement production line for co-disposing solid waste (clinker output 4000 t / d, mixed treatment volume of pulverized coal and solid waste 28 t / h), the system and method provided by the present invention are applied.
[0068] Preferably, a solid waste feeding port is added to the designed entrained flow gasifier 4, and the gasification temperature is controlled at 750 - 850 °C to co-gasify waste plastics / waste rubber and pulverized coal, and the generated fuel gas with CH4 content increased to 7% is produced;
[0069] The designed decomposer burner 7 adopts a variable diameter structure (the inlet is Φ300 mm and tapers to the outlet Φ180 mm), and the fuel flow rate is increased from 6 m / s to 15 m / s to form a strong entrainment effect at the front end of the combustion chamber;
[0070] A hydrogen peroxide concentration monitoring system is designed, and zirconia probes are installed at the outlet of the entrained flow gasifier 4 and the tertiary air duct of the decomposer furnace body 1 to dynamically adjust the excess air coefficient in the range of 1.05 - 1.15;
[0071] Preferably, the system achieves a solid waste substitution rate of 30%, the chlorine content of the kiln tail fly ash is controlled below 0.8%, the comparable comprehensive energy consumption is reduced to 93 kgce / t-cl, and the average hourly NOx emission is < 28 mg / m 3 .
[0072] Common characteristics of the above three examples:
[0073] 1. The entrained flow gasifier 4 all adopts a four-channel counter-jet structure, and the primary air volume is controlled at 20% - 45% of the theoretical value.
[0074] 2. The layout of the decomposer burner 7 all adopts 8 large-diameter counter-jet arrays, the pipe diameter > 200 mm, and the flow rate < 10 m / s.
[0075] 3. Complete conversion of the fuel is achieved through residence time control (gasification section > 5 s / combustion section > 3 s).
[0076] 4. The emission indexes all meet the special emission limits of GB4915 - 2013, and the dioxin is < 0.1 ng-TEQ / m 3 .
[0077] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A cement precalciner combustion system based on pulverized coal preheating gasification, characterized in that The invention comprises a decomposition furnace body (1), a rotary kiln (14) and a grate cooler (13) connected in sequence; the combustion chamber of the decomposition furnace body (1) is located in the middle of the decomposition furnace body (1); a plurality of groups of decomposition furnace burners (7) are arranged circumferentially around the middle of the decomposition furnace body (1); each group of decomposition furnace burners (7) is connected to an entrained flow gasifier (4); an ignition burner (5) is arranged at one end of the entrained flow gasifier (4), and a plurality of gasifier burners (5) are arranged circumferentially around the entrained flow gasifier (4).
2. The cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, The decomposition furnace burners (7) are arranged in four groups along the circumference of the middle part of the decomposition furnace body (1); each group of decomposition furnace burners (7) has two arranged along the axial direction of the decomposition furnace body (1), and a total of eight decomposition furnace burners (7) are arranged in pairs along the radial direction of the decomposition furnace body (1).
3. A cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, Each of the gasifier burners (5) is sequentially connected to a spiral powder feeder (9) and a first fan (101) for conveying cold coal powder into the entrained flow gasifier (4).
4. A cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, A safety valve (12) is provided on the connecting pipeline between the gasifier burner (5) and the spiral powder feeder (9).
5. A cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, One end of the ignition burner (5) is connected to a gas source (11); one side of the ignition burner (5) is connected to a second fan (102).
6. The combustion system of a cement precalciner based on pulverized coal preheating gasification according to claim 1, characterized in that, The outer wall of the decomposition furnace body (1) above the combustion chamber is provided with a secondary air duct (2) and a first raw material inlet (31).
7. A cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, A second raw material inlet (32) and a tertiary air duct (8) are provided on the outer wall of the decomposition furnace body (1) corresponding to the location of the combustion chamber; the second raw material inlet (32) and the tertiary air duct (8) are both located below the decomposition furnace burner (7).
8. A cement precalciner combustion system based on pulverized coal preheating gasification according to claim 1, characterized in that, The diameter of the decomposition furnace burner (7) is not less than 200 mm.
9. A working method of the cement precalciner combustion system based on pulverized coal preheating gasification according to any one of claims 1 to 8, characterized in that, The following steps are involved: The cold pulverized coal is sprayed into the entrained flow gasifier (4) through the gasifier burner (6) and burns in the entrained flow gasifier (4) to become gasification fuel; The gasified fuel is sprayed into the combustion chamber of the decomposition furnace body (1) through the decomposition furnace burner in a counter-flow manner, and is fully burned to participate in the decomposition of cement to obtain cement raw materials; The cement raw material enters the rotary kiln (14) for calcination to obtain cement clinker, which is then cooled and collected by the grate cooler (13).
10. The working method of a cement precalciner combustion system based on pulverized coal preheating gasification according to claim 9, characterized in that, The outer wall of the decomposition furnace body (1) above the combustion chamber is provided with a secondary air duct (2) for air supply, and the air volume of the air supply accounts for 12% to 18% of the total air volume.