Oxy-fuel combustion production system of cement predecomposition rotary kiln

Abstract

The utility model discloses a clinker calcining system for pure oxygen combustion of a rotary kiln, belongs to the field of cement preparation processes, and is used for solving some key problems which need to be solved for practical application of an oxygen-fuel combustion technology how to improve an economic, efficient and stable-running oxygen-fuel combustion system. The device comprises a grate cooler, a rotary kiln, a decomposing furnace, a kiln tail smoke chamber, a tertiary air pipe and a fan, and is characterized in that the rotary kiln adopts high-temperature pure oxygen for combustion, the decomposing furnace adopts hot air for combustion supporting, pure oxygen is conveyed into a grate cooler fixed bed through an oxygen supply pipeline, high-temperature clinker is cooled by the pure oxygen, and the pure oxygen is heated to become high-temperature pure oxygen; the high-temperature pure oxygen serves as secondary air to enter the rotary kiln, and all the secondary air is the high-temperature pure oxygen.

Description

Technical Field

[0001] The utility model belongs to the field of cement preparation technology, in particular to a cement pre-decomposition rotary kiln full oxygen combustion production system. Background Art

[0002] The current new dry process cement production method often has the following problems when the raw material composition fluctuates greatly or when low-quality raw materials and coal powder are used: First, due to the limited calcination temperature, production is extremely unstable, and it is often difficult to burn qualified clinker products. Second, air is usually used to assist combustion, and about 79% of the nitrogen in the air does not participate in the reaction, resulting in high flue gas volume, nitrogen oxides and CO content, and high environmental pressure. Third, the low oxygen concentration in the air brings another typical problem, which is the low combustion temperature of coal powder and low combustion efficiency. In addition, the large amount of flue gas emissions leads to large heat loss and low thermal efficiency. Enterprises have to face high coal consumption and increased costs. In terms of product quality and output, the low calcination temperature also leads to unsatisfactory clinker quality such as strength and high free calcium oxide, and hinders the improvement of the rotary kiln's calcination capacity. There is much room for improvement in both product quality and output.

[0003] Overall, the current new dry-process cement production method shows limitations in terms of clinker quality, economic benefits, energy conservation and consumption reduction, environmental protection, etc. Under the background of "dual carbon" and "dual control", this problem is more prominent. Whether from the perspective of product quality or energy conservation and emission reduction and economy, cement plants have a huge demand to improve and optimize production methods.

[0004] Pure oxygen combustion technology in cement kilns offers high thermal efficiency, low calcination temperatures, and low flue gas emissions, overcoming these challenges and offering promising prospects. However, this technology is still in its infancy. A small number of existing technologies have proposed this concept and preliminary production or combustion methods. For example, CN210862210U proposes a cement calcination production method based on pure oxygen combustion, CN112321183A proposes a cement kiln production method and cement clinker preparation method that achieves zero carbon dioxide emissions, and CN113267053A discloses a production method and method for producing cement clinker using oxyfuel combustion and cyclic preheating. At present, the existing technology has the following key problems that restrict its application: (1) It is difficult to improve, and the promotion and practical application of enterprises are limited. For example, it is clearly recorded in CN210862210U; the total amount of flue gas generated is greatly reduced. Therefore, the specifications of the kiln tail preheater configured for pure oxygen combustion are reduced by 40% compared with the preheater used in conventional cement production lines. A 40% reduction in the specifications of the preheater will greatly reduce the output. The output is directly related to the economic benefits. It is difficult for enterprises to accept improvements at the expense of output. In addition, this method can only be used for newly built production lines. For existing production lines, the size of the preheater is usually constant, the equipment is large and expensive, and it is difficult to directly modify or change it. (2) The process is complex and the cost is high. The existing technology requires oxygen to be introduced into the decomposition furnace and the rotary kiln at the same time. The amount of oxygen required is not only large, but also expensive. The more prominent problem is that it is very easy to cause instability in the decomposition furnace. The above-mentioned processes are relatively complicated. Some technologies even require complex partitioning of the cooler, complex piping layout, and complex processes. Some patents focus on the effect of introducing CO2 gas, which has different focuses. There are many changes and large changes compared with the original production line. The difficulty and degree of production process improvement increase. Enterprises are unwilling to bear the risk and cost of transformation, so it is difficult to promote and apply it to existing production lines. (3) The degree of improvement in thermal efficiency is not enough. A small number of the above-mentioned patents mention the use of heat exchangers to exchange heat between pure oxygen and high-temperature waste heat air to preheat pure oxygen into high-temperature pure oxygen. This indirect heat exchange method using heat exchangers can only directly utilize a small amount of heat in the cooler. Most of the heat can only be used for waste heat power generation, etc., and cannot be directly recycled for cement production. The energy saving level is not enough. The temperature of pure oxygen after preheating only reaches 760-800℃.

[0005] Due to the above-mentioned shortcomings, some key problems need to be solved for the practical application of oxy-fuel combustion technology. There is an urgent need to develop a simple, economical, efficient and stable oxy-fuel combustion system. Utility Model Content

[0006] The purpose of this utility model is to provide a cement pre-decomposition rotary kiln full oxygen combustion production system, which has multiple advantages in terms of raw material adaptability, clinker quality, economic benefits, energy saving and consumption reduction, and also has multiple effects such as simple production system, easy production improvement and stable operation. It can not only be used for new production lines, but also can be directly improved on existing production lines, which is conducive to actual promotion and application, and truly promotes the practical application of green and energy-saving technologies.

[0007] The utility model is realized through the following technical solutions:

[0008] Solution 1: A cement pre-decomposition rotary kiln full oxygen combustion production system, including a grate cooler, a rotary kiln, a decomposition furnace, a kiln tail smoke chamber, a tertiary air duct, and a fan. The rotary kiln uses high-temperature pure oxygen for combustion, and the decomposition furnace uses hot air for combustion. Pure oxygen is transported into the fixed bed of the grate cooler through an oxygen supply pipeline. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. The high-temperature pure oxygen enters the rotary kiln as secondary air, and the secondary air is all high-temperature pure oxygen; ambient air is blown into the grate cooler movable bed air chamber through the fan, and passes through the grate cooler. The clinker cooled by the movable bed and the fixed bed of the grate cooler is heat-exchanged to form hot air, which enters the decomposition furnace as tertiary air. The tertiary air is all hot air, and the smoke chamber shrinkage area of ​​the kiln tail smoke chamber is reduced to maintain the flue gas flow rate entering the decomposition furnace at not less than 25m / s. The oxygen supply pipeline is arranged with a shut-off valve, a flow meter, and a flow regulating valve. The delivery amount of pure oxygen is adjusted through the oxygen supply pipeline according to the combustion characteristics and dosage of the fuel; the rotary kiln includes a burner, and the burner is installed at the center of the rotary kiln.

[0009] Option 2: A cement pre-decomposition rotary kiln full oxygen combustion production system, including a grate cooler, a rotary kiln, a decomposition furnace, a kiln tail smoke chamber, a tertiary air duct, and a fan. The rotary kiln uses high-temperature pure oxygen for combustion, and the decomposition furnace uses hot air for combustion. Pure oxygen is transported into the fixed bed of the grate cooler through the oxygen supply pipeline. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. Ambient air is blown into the air chamber of the movable bed of the grate cooler through the fan. The clinker cooled by the grate cooler movable bed is exchanged with the grate cooler fixed bed to form hot air. The mixed gas formed by mixing the high-temperature pure oxygen and a small amount of hot air is used as the secondary air. Entering the rotary kiln, the secondary air is a mixture of high-temperature pure oxygen and a small amount of hot air, and the high-temperature pure oxygen accounts for no less than 80% of the volume percentage of the secondary air. The hot air enters the decomposition furnace as the tertiary air, and the tertiary air is all hot air. The smoke chamber shrinkage area of ​​the kiln tail smoke chamber is reduced to maintain the flue gas flow rate entering the decomposition furnace at no less than 25m / s; the oxygen supply pipeline is arranged with a shut-off valve, a flow meter, and a flow regulating valve. The delivery amount of pure oxygen is adjusted through the oxygen supply pipeline according to the combustion characteristics and dosage of the fuel; the rotary kiln includes a burner, and the burner is installed at the center of the rotary kiln.

[0010] Compared with the existing technology, the utility model has multiple advantages in terms of clinker quality, economic benefits, energy saving and consumption reduction, and also has multiple effects such as simple production system, easy production improvement and stable operation. The innovative points and beneficial effects are as follows:

[0011] (1) It has a different concept from the existing technology. The existing technology basically introduces oxygen into the rotary kiln and the decomposition furnace at the same time, and takes the introduction of CO2 gas as the key utility model point. Since the gas volume is significantly reduced compared with conventional air combustion, it has to face the problem of reducing the area of ​​the kiln tail preheater and reducing the output. It also faces the risks of unstable production method operation and material collapse. The utility model regards the full oxygen combustion of the rotary kiln, the hot air combustion-assisted combustion of the decomposition furnace and the reduction of the shrinkage area of ​​the wind chamber and smoke chamber as a whole, rather than separated parts. Starting from the whole, it makes a system improvement especially for the pure oxygen combustion, and adopts a combination of the full oxygen combustion of the rotary kiln and the hot air combustion-assisted combustion of the decomposition furnace. The two adopt different combustion-assisted methods and cooperate with each other as a whole in the production method. Compared with the prior art in which oxygen is introduced in multiple ways, the present production method only introduces pure oxygen into the rotary kiln, and the decomposition furnace adopts air combustion-assisted combustion. CO2 gas is not introduced into the entire production method. When the total smoke volume of the rotary kiln is greatly reduced, the wind speed can still be maintained by the air combustion-assisted combustion of the decomposition furnace and the reduction of the shrinkage area of ​​the wind chamber and smoke chamber, so that the decomposition furnace can operate stably. This method avoids reducing the size of the preheater and reducing the output, and the improvement range and difficulty are also greatly reduced. It can not only be used for new production lines, but also is easy to directly improve on existing production lines. The production method has universal applicability.

[0012] (2) Pure oxygen is directly introduced into the fixed bed of the grate cooler through an oxygen supply pipeline for heat exchange. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. The temperature of the high-temperature pure oxygen after heat exchange reaches above 1200°C, and basically all the heat from the clinker cooling can be used for cement production. Compared with the existing technology that uses a heat exchanger to exchange heat between pure oxygen and high-temperature waste heat air, the temperature of the pure oxygen after preheating in the existing technology only reaches 760-800°C, and only a small amount of heat in the cooler can be directly utilized. The heat recovery rate of this production method is significantly improved.

[0013] (3) The use of high-temperature pure oxygen combustion air above 1200°C after heat exchange will produce a flame temperature of 2000°C or above. The radiation heat exchange capacity is 200% higher than that of ordinary air combustion (combustion temperature is generally 1650°C) and 70% higher than that of ordinary oxygen-enriched combustion (flame temperature is 1800°C). The increase in the temperature of the burning zone greatly accelerates the chemical reaction rate of the clinker and greatly increases the calcination capacity of the rotary kiln, which is an inevitable requirement for increasing production. At the same time, as the burning temperature increases, the M1 type C3S content can be increased, the C3A content can be reduced, and the free calcium oxide content can be reduced, thereby improving the strength and grindability of the clinker. The strength of the clinker after calcination can reach 70MPa, and the water consumption of the standard consistency of cement is also reduced, and the adaptability of cement is enhanced. At the same time, this production method can be applied to low-quality coal powder and has the advantage of strong raw material adaptability. It can be applied to raw materials with high KH and high SM that are difficult to burn, and the amount of iron correction raw materials can be reduced or eliminated.

[0014] (4) By adopting full oxygen combustion, the flue gas volume is reduced by 20-40%, the high temperature and tail exhaust fan draft is reduced, the fan power consumption is reduced, and the flue gas carries away less heat. Due to the small heat loss, the coal consumption is also reduced accordingly. In addition, low-temperature liquid oxygen can further enhance heat exchange and improve cooling efficiency. The cooling power consumption of the grate cooler is reduced by about 10%. As previously analyzed, this production method directly enters the fixed bed of the grate cooler through the oxygen supply pipeline for heat exchange. The production method has a high heat recovery efficiency. Therefore, the synergistic heat loss is small, the coal powder combustion efficiency is high, and the heat recovery efficiency is high, which reduces the overall cost of the production line and can bring considerable economic benefits to the enterprise. In addition, after adopting full oxygen combustion, CO, SO2, NO in the tail gas X The atmospheric pollution components such as carbon monoxide and carbon monoxide are greatly reduced, which is conducive to energy conservation and emission reduction.

[0015] (5) Compared with the full oxygen combustion production method disclosed in the prior art, the system of the utility model is simpler, more economical, more efficient, and more stable in operation. It does not require major changes to the original production line, and the difficulty and magnitude of production process improvement are small. It is easier for enterprises to accept and easy to promote and apply in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention can be further described by way of non-limiting examples given in the accompanying drawings;

[0017] Figure 1 This is a structural diagram of a cement pre-decomposition rotary kiln oxy-combustion production system of the utility model;

[0018] Figure 2 This is a schematic diagram of the connection structure between the oxygen supply pipeline and the grate cooler of the utility model;

[0019] Figure numbers: grate cooler fan 1, burner 2, rotary kiln 3, tertiary air duct 4, kiln tail smoke chamber 5, smoke chamber neck 6, decomposition furnace 7, stop valve 101, flow regulating valve 102, flow meter 103, nozzle 104, grate cooler fixed bed 81, grate cooler fixed bed air chamber 82, grate cooler movable bed 91, grate cooler movable bed air chamber 92, kiln head hood 10. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0021] Example 1:

[0022] like Figure 1 , Figure 2 As shown, a cement pre-decomposition rotary kiln full oxygen combustion production system includes a grate cooler, a rotary kiln 3, a decomposition furnace 7, a kiln tail smoke chamber 5, a tertiary air duct 4, and a fan 1. The rotary kiln 3 uses high-temperature pure oxygen for combustion, and the decomposition furnace 7 uses hot air for combustion. Pure oxygen is transported into the grate cooler fixed bed 81 through an oxygen supply pipeline. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. The high-temperature pure oxygen enters the rotary kiln as secondary air, and the secondary air is all high-temperature pure oxygen. Ambient air is blown into the grate cooler movable bed air chamber 92 through the fan 1, and passes through the grate cooler movable bed. 91 exchanges heat with the cooled clinker in the grate cooler fixed bed 81 to form hot air, which enters the decomposition furnace 7 as tertiary air. All tertiary air is hot air. The area of ​​the flue gas chamber constriction 6 of the kiln tail flue gas chamber 5 is reduced to maintain a flue gas velocity of no less than 25 m / s entering the decomposition furnace. The oxygen supply pipeline is equipped with a shutoff valve 101, a flow meter 103, and a flow control valve 102. The oxygen supply pipeline adjusts the delivery rate of pure oxygen based on the combustion characteristics and amount of the fuel. The rotary kiln 3 includes a burner 2, which is installed at the center of the rotary kiln 3. Pure oxygen can be gaseous pure oxygen or low-temperature liquid pure oxygen. When the pure oxygen is gaseous pure oxygen, the end of the oxygen supply pipeline is connected to the grate cooler fan 1, which blows the gaseous pure oxygen into the grate cooler fixed bed air chamber 82 below the grate cooler fixed bed 81. The burner 2 is inserted into the kiln head cover 10 and extends to the rotary kiln 3. The lower end of the kiln head cover 10 is connected to the grate cooler.

[0023] Preferably, pure oxygen is delivered to the fixed bed of the grate cooler through an oxygen supply pipeline, where the pure oxygen cools the high-temperature clinker and heats it to above 1200°C to become high-temperature pure oxygen. The firing zone temperature in the rotary kiln reaches 2000°C or above.

[0024] Example 2:

[0025] like Figure 1 , Figure 2As shown, a cement pre-decomposition rotary kiln full oxygen combustion production system includes a grate cooler, a rotary kiln 3, a decomposition furnace 7, a kiln tail smoke chamber 5, a tertiary air duct 4, and a fan 1. The rotary kiln 3 uses high-temperature pure oxygen for combustion, and the decomposition furnace 7 uses hot air for combustion. Pure oxygen is transported into the grate cooler fixed bed 81 through an oxygen supply pipeline. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. Ambient air is blown into the grate cooler movable bed air chamber 92 through a fan. The grate cooler movable bed 91 exchanges heat with the cooled clinker in the grate cooler fixed bed 81 to form hot air. The mixed gas formed by mixing the high-temperature pure oxygen and a small amount of hot air is used as the second Secondary air enters the rotary kiln. The secondary air is a mixture of high-temperature pure oxygen and a small amount of hot air, with the high-temperature pure oxygen accounting for no less than 80% by volume of the secondary air. The hot air then enters the decomposition furnace 7 as tertiary air, which is entirely hot air. The area of ​​the flue gas chamber 5 at the kiln tail is reduced to maintain a flue gas velocity of no less than 25 m / s entering the decomposition furnace. The oxygen supply pipeline is equipped with a shutoff valve 101, a flowmeter 103, and a flow control valve 102. The oxygen supply flow is regulated through the oxygen supply pipeline based on the combustion characteristics and amount of the fuel. The rotary kiln 3 includes a burner 2, which is mounted at the center of the rotary kiln 3. The pure oxygen can be gaseous pure oxygen or low-temperature liquid pure oxygen. In the case of low-temperature liquid pure oxygen, a nozzle 104 is installed at the end of the oxygen supply pipeline, through which the liquid pure oxygen is sprayed into the hot clinker above the fixed bed of the grate cooler. The burner 2 is inserted into the kiln head cover 10 and extends to the rotary kiln 3. The lower end of the kiln head cover 10 is connected to the grate cooler.

[0026] Preferably, pure oxygen is delivered to the fixed bed of the grate cooler through an oxygen supply pipeline, where the pure oxygen cools the high-temperature clinker and heats it to above 1200°C to become high-temperature pure oxygen. The firing zone temperature in the rotary kiln reaches 2000°C or above.

[0027] When the pure oxygen is liquid pure oxygen, it is connected to the fixed bed of the grate cooler through an oxygen supply pipeline. A stop valve 101, a flow meter 103, a flow regulating valve 102 and a nozzle 104 are arranged on the oxygen supply pipeline. Liquid pure oxygen is sprayed into the top of the fixed bed of the grate cooler through the nozzle to exchange heat with the hot clinker. The use of the nozzle can further increase the contact area between oxygen and clinker. During use, the delivery amount of liquid oxygen can be adjusted through the oxygen supply pipeline according to the combustion characteristics of the fuel, and the flow regulating valve can be used to control the flow of oxygen to ensure that the amount of oxygen entering the grate cooler meets the combustion of the fuel in the kiln.

[0028] Alternatively, when the pure oxygen is gaseous pure oxygen, it is blown into the fixed bed air chamber of the grate cooler through the grate cooler fan at the end of the oxygen supply pipeline.

[0029] After preliminary experiments, the utility model can achieve the following effects:

[0030] (1) The flame temperature is high and the heat transfer efficiency is high. Through full oxygen combustion, the flame temperature in the kiln can reach 2000℃ and above. The radiation heat exchange capacity is about 200% higher than that of ordinary air combustion (combustion temperature is generally 1650℃) and more than 70% higher than that of general oxygen-enriched combustion (flame temperature 1800℃).

[0031] (2) The production method has a wide range of raw material adaptability and good clinker performance. It can be applied to low-quality pulverized coal. It also has the advantage of strong raw material adaptability and can be applied to raw materials with poor burnability, such as high KH and high SM, and can reduce or eliminate the use of iron correction raw materials. As the firing temperature increases, the M1 type C3S content can be increased, the C3A content can be reduced, and the free calcium oxide content can be reduced, thereby improving the clinker strength, grindability and other properties. The strength of the calcined clinker can reach 70MPa. The water consumption of the standard consistency of cement is also reduced, and the adaptability of the cement is enhanced.

[0032] (3) The flue gas volume is reduced. The theoretical flue gas volume of the preheater outlet in the existing production process is about 1.0Nm 3 / kg.cl(heat consumption

[0033] 100kgce / kg.cl), actual flue gas volume 1.2-1.4Nm 3 / kg.cl. Using this technical solution, the flue gas volume at the preheater outlet is reduced to 0.7-0.8Nm 3 / kg.cl. The flue gas volume is reduced by 20-40%, the exhaust heat loss is reduced accordingly, and the CO, SO2, NO X The atmospheric pollution components such as GHG have been greatly reduced.

[0034] (4) Reduce coal consumption. Using this technical solution, the flue gas temperature is reduced, the heat carried away by the flue gas is reduced, and the surface heat dissipation loss is reduced, which can reduce the amount of coal used in the kiln head, and the total energy saving reaches 10-12kgce / kg.cl.

[0035] (5) Reduce power consumption. The flue gas volume at the preheater outlet is reduced, and the draft of the high-temperature and tail exhaust fans is reduced, resulting in a 12%-15% reduction in power consumption. When liquid pure oxygen is sprayed into the fixed bed, the cooling power consumption of the grate cooler is further reduced by about 10%-12%.

[0036] (6) Increase the output. The increase of the temperature in the burning zone greatly accelerates the chemical reaction rate of the clinker and greatly increases the calcining capacity of the rotary kiln. The output is increased by about 15%-20% compared with the conventional production line.

[0037] Specific implementation cases

[0038] During the renovation and commissioning of a 2500t / d cement clinker production line, we discovered an oxygen production company approximately 1km away that could provide oxygen. Therefore, we conducted calcination experiments on the line using air, 80% oxygen-enriched oxygen, and pure oxygen as the combustion media. The experiments lasted three weeks, with each combustion medium calcining for one week. During the experiments, the kiln system's raw materials remained stable. The chemical analysis of the raw material is shown in Table 1, and the industrial analysis of the pulverized coal is shown in Table 2. The experimental results are shown in Table 3:

[0039] Table 1 Chemical analysis of raw materials

[0040]

[0041] Table 2 Analysis of pulverized coal industry

[0042] project Moisture content (%) Ash content (%) Volatile matter (%) Calorific value Numerical 0.60 20.51 28.16 6030

[0043] Table 3 Experimental results

[0044]

[0045]

[0046] From the above table, we can see that compared to the existing air technology, our improved equipment is connected to the fixed bed of the grate cooler through an oxygen supply pipeline. The oxygen supply pipeline is equipped with a shut-off valve 101, a flow meter 103, a flow regulating valve 102, and a nozzle 104. Liquid pure oxygen is sprayed into the grate plate above the fixed bed of the grate cooler through the nozzle to exchange heat with the hot clinker. The use of the nozzle can further increase the contact area between oxygen and clinker. After use, coal consumption and electricity consumption are greatly reduced, and the clinker output and quality are significantly improved. For example, when the combustion medium is air, the output is 2500t / d, when the oxygen content is 80%, the output is 2900t / d, and when the oxygen content is 100%, the output is 3000t / d.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cement precalcining rotary kiln oxy-combustion production system, comprising a grate cooler, a rotary kiln, a calciner, a kiln tail smoke chamber, a tertiary air duct, and a fan, characterized by: The rotary kiln uses high-temperature pure oxygen for combustion, and the decomposition furnace uses hot air for combustion support. Pure oxygen is transported into the fixed bed of the grate cooler through an oxygen supply pipeline. The pure oxygen cools the high-temperature clinker and heats up to become high-temperature pure oxygen. Ambient air is blown into the air chamber of the movable bed of the grate cooler by a fan. The movable bed of the grate cooler exchanges heat with the cooled clinker in the fixed bed of the grate cooler to form hot air. The mixed gas of the high-temperature pure oxygen and a small amount of hot air enters the rotary kiln as secondary air. The secondary air is a mixture of high-temperature pure oxygen and a small amount of hot air. The high-temperature pure oxygen accounts for no less than 80% by volume of the secondary air. The hot air enters the decomposition furnace as tertiary air. The tertiary air is entirely hot air. The smoke chamber constriction area of ​​the kiln tail smoke chamber is reduced to maintain a flue gas flow rate of no less than 25 m / s entering the decomposition furnace. The oxygen supply pipeline is equipped with a shut-off valve, a flow meter, and a flow regulating valve. The pure oxygen delivery rate is adjusted through the oxygen supply pipeline according to the combustion characteristics and amount of the fuel. The rotary kiln includes a burner, which is installed at the center of the rotary kiln.

2. A cement pre-decomposition rotary kiln oxy-combustion production system according to claim 1, characterized in that: The pure oxygen is gaseous pure oxygen or low-temperature liquid pure oxygen.

3. A cement pre-decomposition rotary kiln oxy-combustion production system according to claim 2, characterized in that: When the pure oxygen is gaseous pure oxygen, the end of the oxygen supply pipeline is connected to the grate cooler fan, and the gaseous pure oxygen is blown into the grate cooler fixed bed air chamber below the grate cooler fixed bed through the grate cooler fan.

4. A cement pre-decomposition rotary kiln oxy-combustion production system according to claim 3, characterized in that: When the pure oxygen is low-temperature liquid pure oxygen, a nozzle is installed at the end of the oxygen supply pipeline, and the liquid pure oxygen is sprayed into the hot clinker above the fixed bed of the grate cooler through the nozzle at the end of the oxygen supply pipeline.

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