Method and system for generating cement clinker with pre-calcining furnace

Abstract

The present invention relates to a cement clinker generation system having a pre-calcining furnace, comprising: a preheating unit suitable for preheating a cement raw material; the decomposing unit is suitable for decomposing the cement materials from the preheating unit; the separator is suitable for separating the cement materials from the decomposition unit; the pre-calcining furnace is suitable for performing pre-calcining treatment on the cement material from the separator; a firing unit; and a cooling unit adapted to cool the cement material from the firing unit, the system comprising a first circulation loop of particles and / or flue gas formed among the decomposition unit, the separator and the pre-calcining furnace, the particles and / or flue gas from the pre-calcining furnace being adapted to enter the decomposition unit. By controlling the flow direction of the high-temperature flue gas of each part in the whole system, the high-temperature flue gas can provide heat for the reaction of each part, the matching of the temperature (heat) and the reaction in the whole reaction process is realized, and the generation amount of thermal NOx of the system is further reduced.

Description

Technical Field

[0001] The invention relates to the technical field of cement, and in particular to a method and a system for producing cement clinker with a pre-calcining furnace. Background Art

[0002] Cement clinker calcination mainly includes the following processes: 1) raw material preheating and CaCO 3 Decomposition (800-900°C); 2) 2CaO·SiO 2 (C 2 S) generated (900~1200℃); 3) 3CaO·SiO 2 (C 3 S) is generated (>1300℃). The new dry process cement production process is based on suspension preheating and pre-decomposition outside the kiln. It has the advantages of low heat consumption, large single kiln production capacity, and easy operation of the automated process. It is currently a relatively mature technology.

[0003] In the new dry process cement production process, raw material preheating and main decomposition process (<900℃) are mainly completed in 5-6 stage cyclone and decomposition furnace equipment, while the decomposition and C 2 S (dicalcium silicate) calcined and C 3 S (tricalcium silicate) sintering is mainly completed in rotary kiln equipment (1000-1800℃). The rotary kiln has a large rotation power and a large volume. The heat and mass transfer in the kiln is in an accumulation state, and the heat exchange efficiency of gas, liquid and solid is low. At present, the heat consumption and cost of the rotary kiln cannot be further reduced, and the maximum thermal efficiency can only reach about 60%, and it has been unable to break through the process bottleneck.

[0004] In addition, the temperature of the cement kiln head is as high as 1800℃, which makes the rotary kiln contribute 80% of the thermal type and 40% of the fuel type NO x This is also one of the reasons why cement kilns are an important source of fossil energy consumption and environmental pollution.

[0005] Utilize the high efficiency heat and mass transfer of fluidization to increase the temperature of raw materials entering the kiln and transfer the intermediate product C 2The calcination of S is taken out of the rotary kiln and carried out under fluidized conditions, which is expected to speed up the burning process of the materials entering the kiln, greatly increase the clinker output, and reduce the heat consumption level. Chinese patent CN100534941C discloses a cement pre-sintering production method and system, which increases the temperature of the materials entering the rotary kiln from the lowest cyclone to 950-1250°C, greatly reducing the inefficient heat transfer process in the rotary kiln. Chinese patent CN211902918U discloses a device for reducing nitrogen oxide emissions and cement manufacturing equipment, in which a pipe-shaped combustion chamber is set between the decomposition furnace and the smoke chamber, and the flue gas containing high nitrogen oxides at the outlet of the smoke chamber is passed into the combustion chamber, and the nitrogen oxides are reduced at high temperature by forming CO in the combustion chamber, which greatly reduces nitrogen oxide emissions.

[0006] The new dry process cement production process adopts rotary kiln firing, which is bulky and has high heat consumption. 2 S calcined and C 3 S sintering is carried out in a rotary kiln. The flue gas temperature at the kiln head is too high (1800℃) and the combustion temperature is uneven, resulting in high NOx emissions and low energy utilization.

[0007] The existing cement pre-sintering method simply and directly increases the temperature of the decomposition furnace and C5 preheater to 950-1250°C, without optimizing the combustion process and taking effective measures to prevent crusting. As a result, the problem of high-temperature crusting and blockage in the preheater at the outlet of the decomposition furnace cannot be solved, making it difficult for the system to operate stably for a long time. In addition, the pre-sintering quality of fine material particles cannot be guaranteed.

[0008] In the prior art, a pipe-shaped smoke chamber is added between the decomposition furnace and the smoke chamber for NOx reduction, but the high temperature of this section is not fully utilized for pre-sintering of raw materials. Summary of the invention

[0009] The present invention is proposed to solve at least one aspect of the technical problems in the prior art.

[0010] According to one aspect of an embodiment of the present invention, a system for producing cement clinker with a pre-calcining furnace is provided, comprising:

[0011] A preheating unit, adapted to perform preheating treatment on cement raw materials;

[0012] A decomposition unit, adapted to decompose the cement material from the preheating unit;

[0013] A separator, adapted to separate cement material from the decomposition unit;

[0014] A pre-calcining furnace, suitable for pre-calcining the cement material from the separator;

[0015] A calcining unit, suitable for calcining cement materials from the pre-calcining furnace;

[0016] a cooling unit adapted to cool the cement material from the firing unit, the cooled cement clinker being adapted to be discharged from the cooling unit,

[0017] in:

[0018] The system comprises a first circulation loop of particles and / or flue gases formed between a decomposition unit, a separator and a precalciner, particles and / or flue gases coming from the precalciner being adapted to enter the decomposition unit.

[0019] According to another aspect of an embodiment of the present invention, a method for producing cement clinker is provided, comprising the steps of:

[0020] A preheating unit, a decomposition unit, a separator, a precalcining furnace, a burning unit and a cooling unit are provided, wherein the preheating unit is suitable for preheating the cement raw material, the decomposition unit is suitable for decomposing the cement material from the preheating unit, the separator is suitable for separating the cement material from the decomposition unit, the precalcining furnace is suitable for precalcining the cement material from the separator, the burning unit is suitable for burning the cement material from the precalcining furnace, and the cooling unit is suitable for cooling the cement material from the burning unit; and

[0021] A first circulation loop of particles and / or flue gas is formed between the decomposition unit, the separator and the precalciner, so that particles and / or flue gas from the precalciner enter the decomposition unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed by the present invention, in which the same reference numerals always represent the same components, wherein:

[0023] Figure 1 A flow chart for cement clinker generation according to an exemplary embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 1 The flowchart shown corresponds to;

[0025] Figure 3 A flow chart for cement clinker generation according to another exemplary embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 3 The flowchart shown corresponds to;

[0027] Figure 5 A flow chart of cement clinker generation according to another exemplary embodiment of the present invention;

[0028] Figure 6 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 5 The flowchart shown corresponds to the following.

[0029] Reference numerals:

[0030] 10 preheating unit;

[0031] 20 decomposition units;

[0032] 30 separation unit, 31 separator, 32 first air lock flap valve;

[0033] 40 pre-calcining unit, 41 pre-calcining furnace, 42 second air lock flap valve;

[0034] 50 firing units;

[0035] 60 cooling units. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further specifically described below by examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0037] Figure 1 FIG. 1 is a flow chart of cement clinker production according to an exemplary embodiment of the present invention. Figure 1 As shown, in Figure 1 The cement clinker production system shown includes six units, namely a preheating unit 10, a decomposition unit 20, a separation unit 30, a pre-calcination unit 40, a sintering unit 50, and a cooling unit 60.

[0038] like Figure 1 As shown, the cement raw meal enters the preheating unit 10 (preheating subsystem), and exchanges heat with the high-temperature flue gas (e.g., the temperature is 800-900° C.) from the separation unit 30 in the preheating unit 10. The raw meal is preheated and part of the CaCO 3 Decomposition, to achieve the recovery of flue gas heat, the preheated flue gas (which can be less than 300°C) is discharged. In one embodiment of the present invention, the operating temperature of the preheating unit 10 is less than 900°C. Furthermore, Figure 1 Shown is less than 800°C.

[0039] Next, complete the preheating and CaCO 3The decomposed raw material enters the decomposition unit 20 ( Figure 1 The decomposition furnace is shown in FIG. 2 . The decomposition unit 20 is fed with fuel and air distribution, and receives flue gas / coal gas and fine particles from the pre-calcination unit 40 at the same time. The decomposed cement material enters the lowest separator of the separation unit 30, and the separated cement material enters the pre-calcination unit 40. The calcination reaction of C2S is completed in the pre-calcination unit 40. The pre-calcination unit 40 is fed with fuel and air distribution, and the fuel combustion provides the heat required for the C2S calcination reaction. The high-temperature flue gas / coal gas and fine powder particles formed by the pre-calcination unit 40 enter the decomposition unit 20, and participate in the preheating of cement raw materials and CaCO 3 Decomposition process.

[0040] In one embodiment of the present invention, the operating temperature of the preheating unit 10 is below 800°C, the operating temperature of the decomposition unit 20 is between 800-900°C, the operating temperature of the lowest cyclone (or separator) of the separation unit 30 is between 800-900°C, and the operating temperature of the pre-calcining unit 40 is between 1000-1200°C.

[0041] like Figure 1 As shown, the pre-calcined material enters the sintering unit 50 (i.e., a rotary kiln. Figure 1 The short rotary kiln is used in the present invention because compared with the long rotary kiln in the prior art, after the pre-calcination process is adopted, as mentioned later, the total coal consumption of the calciner + rotary kiln is significantly lower than the coal consumption / energy consumption of the single rotary kiln, and the length of the existing rotary kiln can be reduced by more than 1 / 3), and the cement material is burned in C3S to form high-temperature clinker. The burning unit 50 is fed with fuel and air distribution, and the operating temperature is, for example, between 1200 and 1700°C.

[0042] The fired high-temperature cement clinker enters the cooling unit 60, and after cooling, the clinker temperature drops to below 100°C. The cooling air recovers the heat of the clinker, and the preheated hot air can enter the firing unit 50, the pre-calcining unit 40 and the decomposition unit 20 as the distribution air to participate in the fuel combustion to make full use of the heat.

[0043] In the present invention, the main reactions of the cement clinker burning process are controlled in different regions, and more accurate reaction control is achieved by controlling the temperature of each region, specifically including: cement raw material preheating is completed in the preheating unit 10 (<900°C), raw material decomposition is completed in the decomposition unit 20 (800-900°C), the separation of the decomposed materials is completed in the lowest cyclone (800-900°C) of the separation unit 30, C2S burning is completed in the pre-calcining unit 40 (1000-1200°C), C3S burning is completed in the burning unit 50 (1200-1700°C), and clinker cooling and sensible heat recovery are completed in the cooling unit 60 (<100°C). Since the optimal reaction temperatures of different reactions are different during the cement clinker burning process, the temperature (heat) and chemical reaction process can be matched through the regional control of different reactions in the cement clinker burning process, thereby greatly reducing the heat load of the clinker burning zone, avoiding or reducing the heat loss and low chemical reaction rate caused by temperature mismatch when C2S calcination and C3S burning are completed in the same burning zone.

[0044] In addition, Figure 1 In the embodiment shown, in the first circulation loop formed between the decomposition unit 20, the separation unit 30 and the pre-calcination unit 40, the high-temperature flue gas / coal gas and fine powder particles generated by the pre-calcination unit 40 enter the decomposition unit 20 for decomposition of the cement raw material, and the flue gas / coal gas does not enter the firing unit 50, which can greatly reduce the flue gas volume of the firing unit 50, thereby reducing the amount of thermal NOx generated in the system. In addition, the pre-calcination unit 40 can be a reducing atmosphere, and the high-temperature coal gas enters the decomposition unit 20 to reduce NOx.

[0045] By building a circulation loop between the units, the system operation is made safer and more stable. Through control, multiple circulations of hot flue gas, hot air and fine material particles can be achieved, ensuring full utilization of heat.

[0046] Figure 2 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 1 The flowchart shown corresponds to the following.

[0047] exist Figure 2 In the illustrated embodiment, the separation unit 30 includes a separator 31 and a first air-locking flap valve 32 , and the pre-calcining unit 40 includes a pre-calcining furnace 41 and a second air-locking flap valve 42 .

[0048] like Figure 2As shown, the upper part of the pre-calcining furnace 41 of the pre-calcining unit 40 is provided with a first circulation outlet D2, the lower part is provided with a first material outlet D3, and the pre-calcining furnace 41 is also provided with a first circulation inlet D1. In the present invention, the upper part of a component includes the top or upper part of the component, and the lower part of a component includes the bottom or lower part of the component.

[0049] In other optional embodiments, the first circulation inlet D1 can also be set at the lower part of the pre-calcining furnace 41, for example, at the lower middle part of the side wall of the pre-calcining furnace 41, and the cement material from the separator 31 enters the pre-calcining furnace 41 through the first circulation inlet D1.

[0050] like Figure 2 As shown, the pre-calcining furnace 41 is also provided with a preheating air inlet D4 and a fuel inlet D5. Figure 2 In the illustrated embodiment, the preheating air inlet D4 and the fuel inlet D5 are both disposed at the lower portion of the pre-calcining furnace 41. In other optional embodiments, the preheating air inlet D4 and the fuel inlet D5 may both be disposed at the upper portion of the pre-calcining furnace 41.

[0051] like Figure 2 As shown, the separator 31 is provided with an upper outlet C1, a lower outlet C4, a second material inlet C2 and a second circulation inlet C3 (for flue gas circulation), and the lower outlet C4 of the separator 31 is communicated with the first circulation inlet D1 of the pre-sintering furnace 41.

[0052] The decomposition unit 20 is provided with a second material outlet B2, a second circulation outlet B3 (for flue gas circulation), a third circulation inlet B4, and a third material inlet B1. Among them, the third material inlet is arranged at the lower part of the decomposition unit 20, and the cement raw material enters the decomposition unit 20 from the third material outlet A1 of the preheating unit 10 through the third material inlet B1 after being preheated by the preheating unit 10. The second material inlet C2 of the separator 31 is communicated with the second material outlet B2 of the decomposition unit 20, and the upper outlet C1 of the separator 31 is communicated with the fifth circulation inlet A2 of the preheating unit 10.

[0053] Optionally, the decomposition unit 20 is also provided with fuel and air distribution ports, and external fuel (such as coal) enters the decomposition unit 20 through the fuel inlet D5 to provide heat for the decomposition reaction through the combustion of the fuel.

[0054] In the embodiment of the present invention, the cement clinker production system includes a first circulation loop of particles and / or flue gas formed between the decomposition unit 20, the separator 31 and the pre-calcining furnace 41 (the particles here can be understood as solid particles suitable for flowing with the flue gas or being carried by the flue gas). Specifically, Figure 1 He Ru Figure 2As shown, the particles and / or flue gas from the precalcining furnace 41 enter the decomposition unit 20 through the first circulation outlet D2, and the particles and / or flue gas from the decomposition unit 20 enter the separator 31 through the second circulation outlet B3. Figure 2 In the illustrated embodiment, the second circulation outlet B3 on the decomposition unit 20 is communicated with the second circulation inlet C3 on the separator 31 , and the second material outlet B2 on the decomposition unit 20 is communicated with the second material inlet C2 on the separator 31 .

[0055] In the embodiment of the present invention, different units are connected via delivery pipelines.

[0056] like Figure 2 As shown, the preheating unit 10 is provided with a fifth circulation inlet A2, a raw material inlet, a flue gas outlet, and a third material outlet A1.

[0057] The third material outlet A1 of the preheating unit 10 is connected to the third material inlet B1 of the decomposition unit 20 through a conveying pipeline, and the fifth circulation inlet A2 of the preheating unit 10 is connected to the upper outlet C1 of the separator 31. The cement raw material completes the preheating and partial decomposition process (for example, <900°C) in the preheating unit 10. The third material outlet A1 of the preheating unit 10 is set at the lower part, and the third material inlet of the decomposition unit 20 is set at the lower part. Figure 2 In the illustrated embodiment, the lower portion of the preheating unit 10 is communicated with the lower portion of the decomposition unit 20 .

[0058] The preheated cement raw material completes the decomposition process in the decomposition unit 20 (e.g., 800-900° C.), and the upper part of the decomposition unit 20 is a flue gas and material outlet, which is connected to the inlet of the lowest separator 31 of the separation unit 30. Figure 2 In the illustrated embodiment, the second material outlet B2 of the decomposition unit 20 is a cement material outlet, and the second circulation outlet B3 of the decomposition unit is a smoke outlet (the smoke may carry particles).

[0059] Although not shown, in an optional embodiment, the second material outlet B2 and the second circulation outlet B3 on the decomposition unit 20 may be the same outlet.

[0060] The separation unit 30 includes a separator 31 (e.g., 800-900°C) and a first air-locking flap valve 32, wherein a second material inlet C2 of the separator 31 is connected to a second material outlet B2 of the decomposition unit 20, and a second circulation inlet C3 of the separator 31 is connected to a second circulation outlet B3 of the decomposition unit 20, and the separator 31 is used to separate the material and flue gas entering the separator 31.

[0061] In one embodiment of the present invention, the second material inlet C2 and the second circulation inlet C3 on the separator 31 may be the same inlet, and the second material outlet B2 and the second circulation outlet B3 on the decomposition unit may be the same outlet.

[0062] The upper outlet C1 of the separator 31 is connected to the fifth circulation inlet A2 of the preheating unit 10, and the flue gas in the separator 31 enters the preheating unit 10 through the upper outlet C1 to provide heat for preheating the cement raw material, and the lower outlet C4 of the separator 31 is connected to the first air-locking flap valve 32, and the first air-locking flap valve 32 transports the separated cement material to the precalcining furnace 41. In the embodiment of the present invention, the air-locking flap valve is a high-temperature resistant air-locking flap valve.

[0063] The pre-calcining unit 40 includes a pre-calcining furnace 41 (whose operating temperature range is, for example, 1000-1200°C) and a second air-locking flap valve 42, wherein the first circulation inlet D1 (upper material inlet) provided in the pre-calcining furnace 41 is connected to the first air-locking flap valve 32. A first circulation outlet D2 is provided at the upper part of the pre-calcining furnace, wherein the first circulation outlet D2 is a flue gas outlet and is connected to a third circulation inlet B4 provided at the middle and lower part of the decomposition unit 20. The pre-calcining furnace 41 transports high-temperature flue gas (1000-1200°C) and uncalcined fine material particles to the decomposition unit 20, providing heat for the raw material decomposition of the decomposition unit 20. A first material outlet D3 is provided at the lower part of the pre-calcining furnace 41, and the first material outlet D3 is connected to the second air-locking flap valve 42. The decomposed material completes the calcining process (for example, 1000-1200°C) of the clinker to generate intermediate products, mainly C2S, in the pre-calcining furnace 41. The large particles after calcination are transported to the calcining unit 50 through the second air-locking flap valve 42 for the final clinker calcining process (for example, 1200-1700°C).

[0064] The inlet section of the calcining unit 50 is provided with a first material inlet E1, which is connected to the outlet of the second air-locking flap valve 42 of the pre-calcining unit 40. The high-temperature cement material transported by the second air-locking flap valve 42 enters the calcining unit 50 to complete the calcining process of the final clinker. The inlet section of the calcining unit 50 is also provided with a smoke outlet E2, which is connected to the lower part of the decomposition unit 20. Figure 2 In the embodiment shown, the flue gas outlet E2 of the inlet section of the sintering unit 50 is connected to the fourth circulation inlet B5 of the lower part of the decomposition unit 20. The high-temperature flue gas (1000-1200°C) after completing heat exchange with the cement material enters the decomposition unit 20 to provide heat for the decomposition reaction of the cement raw material. The temperature in the decomposition unit 20 is controlled by the amount of raw material and the amount of coal fed.

[0065] In an optional embodiment, the decomposition unit 20 is provided with a temperature control device, wherein the temperature control device includes a cement material control unit and a fuel control unit.

[0066] The temperature and crust formation of the kiln tail smoke chamber of the firing unit 50 are controlled by introducing a small amount of raw material and blowing and clearing. The lower material outlet of the firing unit 50 is connected to the inlet of the cooling unit 60, and the cement material enters the cooling unit 60 for quenching and cooling.

[0067] The clinker cooling unit 60 is used to pass cooling air to cool the clinker.

[0068] In an optional embodiment, the cooling unit 60 is provided with a first air port F1 and a second air port F2. The cooling air enters the cooling unit 60 through the first air port F1 to cool the cement material. After heat exchange, the cooling air becomes hot air. The preheated hot air is fully utilized. The cooling air preheated in the cooling unit 60 enters the decomposition unit 20, the precalcining furnace 41 and the sintering unit 50 through the second air port F2 to provide the air volume required for combustion. The cooled clinker (e.g., <100°C) is discharged from the cooling unit 60.

[0069] Embodiments of the present invention also include multiple circulation loops. First, as mentioned above, Figure 1 and Figure 2 As shown, a first circulation loop of particles and / or flue gas is formed by the decomposition unit 20, the separator 31 and the precalciner 40, the particles and / or flue gas from the precalciner 41 enter the decomposition unit 20, and the particles and / or flue gas from the decomposition unit 20 enter the separator 31 through the second circulation outlet B3. The first circulation loop also includes the decomposition unit 20, the second circulation outlet B3, the second circulation inlet C3, the separator 31, the lower outlet C4, the first circulation inlet D1, the precalciner 40, the first circulation outlet D2, and the third circulation inlet B4.

[0070] In an optional embodiment, the cement clinker production system of the present invention further includes a second circulation loop formed between the preheating unit 10, the decomposition unit 20 and the separator 31, the particles and / or flue gas from the separator 31 enter the preheating unit 10, the material from the preheating unit 10 enters the decomposition unit 20, and the material from the decomposition unit 20 (including the material after the cement raw material is decomposed, flue gas and / or particles) is passed into the lowest separator 31 of the separation unit 30. In the second circulation loop, it also includes a second material outlet B2, a second material inlet C2, a second circulation outlet B3, a second circulation inlet C3, an upper outlet C1, and a fifth circulation inlet A2.

[0071] In a further embodiment, the cement clinker production system of the present invention further includes a third circulation loop formed between the decomposition unit 20, the separator 31, the pre-calcining furnace 41 and the firing unit 50. The flue gas outlet E2 of the firing unit 50 is connected to the lower part of the decomposition unit 20. After the high-temperature flue gas from the pre-calcining furnace 40 enters the firing unit 50 through the first material inlet E1, after heat exchange, the high-temperature flue gas enters the fourth circulation inlet B5 of the decomposition unit 20 through the flue gas outlet E2 of the inlet section of the firing unit 50. The third circulation loop includes the first material inlet E1, the flue gas outlet E2, and the fourth circulation inlet B5.

[0072] The following is an example Figure 2 The specific processing flow of the embodiment shown.

[0073] The cement raw material enters from the inlet section of the preheating unit 10, and exchanges heat with the high-temperature flue gas from the outlet C1 of the lowest separator 31 of the separation unit 30, and the temperature is controlled below 900°C; the preheated cement raw material enters the decomposition unit 20 from the third material inlet B1 of the decomposition unit 20, and is suspended and calcined to complete the decomposition of the cement raw material. The heat required for the decomposition of the cement raw material is provided by three parts: 1. The fuel combustion (such as coal powder combustion) entering from the lower part of the decomposition unit 20; 2. The high-temperature flue gas from the firing unit 50 entering from the lower part of the decomposition unit 20; 3. The high-temperature flue gas / coal gas from the pre-calcining furnace 40 entering from the third circulation inlet B4 at the lower part of the decomposition unit 20.

[0074] The decomposed cement material is separated by the separator 31 and conveyed by the high temperature resistant first air lock flap valve 32, and then enters the pre-calcining furnace 41 for fluidized calcination to complete C 2 S sintering and granulation of some particles, fuel and air (preheated air from cooling unit 60) are supplied from the lower part of precalcining furnace 41 to provide C 2 The heat required for S sintering and partial granulation is controlled at a temperature of 1000-1200°C in the pre-calcining furnace 41.

[0075] The particles from the pre-calcining furnace 41 are transported to the sintering unit 50 via the high temperature resistant second air lock flap valve 42. The pre-calcining furnace 41 can be an oxidizing or reducing atmosphere, and the high temperature flue gas / coal gas generated goes out through the first circulation outlet D2 at the top of the pre-calcining furnace 41 and enters the third circulation inlet B4 at the middle and lower part of the decomposition unit 20, providing part of the heat for the decomposition of the raw material. At the same time, the high temperature coal gas generated under the reducing atmosphere can reduce the nitrogen oxides in the high temperature flue gas entering the decomposition unit 20 from the sintering unit 50, greatly reducing NO x .

[0076] The firing unit 50 is used to fire cement clinker, and the heat required is provided by fuel combustion, and the temperature is controlled at 1200-1700°C. The large-particle cement clinker fired in the firing unit 50 enters the cooling unit 60 for cooling. The upper part of the firing unit 50 is provided with a return port (i.e., E1) connected to the pre-firing furnace 41, and the return port is provided with a high-temperature resistant second air-locking flap valve 42. At the same time, the upper part of the firing unit 50 is provided with a flue gas channel (i.e., through E2) connected to the lower part of the decomposition unit 20.

[0077] The lower part of the sintering unit 50 is connected to the clinker cooling unit 60. The cooling air is introduced into the lower part of the cooling unit 60 to cool the large-particle cement clinker entering the cooling unit 60 and then discharge it. The hot air preheated by the clinker in the cooling section is used as the combustion air supply for the sintering unit 50, the pre-calcining furnace 41 and the decomposition unit 20, making full use of the heat.

[0078] The cement raw material is subjected to the following process in the cement clinker burning method of the present invention: preheating (<900°C) → decomposition (800-900°C) → 2 S sintering (1000~1200℃) → C 3 S sintering (1200~1700℃)→cooling (<100℃)→clinker discharge process.

[0079] In the present invention, 1) high temperature flue gas provides heat for preheating cement raw materials; 2) the preheated cement raw materials are decomposed in the decomposition furnace in the decomposition unit; 3) the decomposed cement materials are clinkered in the precalcining furnace to form the key intermediate product C 2 S formation reaction and partial particle granulation; 4) by controlling the wind speed of the pre-calcining furnace, the fine particles that have not completed pre-calcination continue to participate in the above 2) to 3) to form a cycle, while the larger particles that have completed pre-calcination enter the rotary kiln for C 3 S sintering; 5) by controlling the flow direction of high-temperature flue gas in each part of the whole system, the high-temperature flue gas provides heat for each part of the reaction, and the temperature (heat) and reaction are matched in the whole reaction process. In the present invention, an air supply control unit can be set to control the wind speed of the preheating air or combustion air entering the pre-calcining furnace.

[0080] The present invention retains the functions and operating temperature range of the preheating system (corresponding to the preheating unit), decomposition furnace (corresponding to the decomposition unit), rotary kiln (corresponding to the sintering unit) and grate cooler (corresponding to the cooling unit) in the existing new dry cement production process. Before the cement material after decomposition enters the rotary kiln, a suspended / fluidized pre-calcining furnace is set up, and the calcination reaction mainly based on dicalcium silicate completed in the form of accumulation in the rotary kiln is carried out under suspended / fluidized conditions, which greatly improves the heat transfer efficiency, reaction rate and activity of the material entering the rotary kiln. In addition, after the calcining furnace is added, the total coal consumption of the calcining furnace + rotary kiln is significantly lower than the coal consumption / energy consumption of a single rotary kiln, and the length of the existing rotary kiln can be reduced by more than 1 / 3, or the length of the existing rotary kiln can be kept unchanged, while the clinker output is greatly improved.

[0081] In the present invention, the high-temperature flue gas generated by the precalcining furnace is introduced into the lower part of the decomposition furnace to achieve high-temperature flue gas classification in the decomposition furnace, strengthen the reducing atmosphere in the decomposition furnace, and facilitate NOx reduction; the material (high temperature, smoke-free) separated by the lowest separator in the existing new dry cement production process is introduced into the precalcining furnace for suspended high-temperature precalcination. The precalcining furnace can be a reducing atmosphere, which can effectively reduce the amount of thermal NOx generated by clinker burning. The temperature of the decomposition furnace and the temperature range of the lowest separator are maintained unchanged to effectively prevent crusting. The overall flue gas volume is reduced, and the heat loss of exhaust gas is reduced. The precalcining furnace has a simple structure, simple on-site transformation, and low transformation cost and transformation amount.

[0082] Figure 3 A flow chart for cement clinker generation according to another exemplary embodiment of the present invention; Figure 4 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 3 The flowchart shown corresponds to the following.

[0083] Figure 3-Figure 4 The embodiment shown is Figure 1-Figure 2 The embodiment shown differs in that Figure 4 In the embodiment, the first circulation inlet D1 of the pre-calcining furnace 41 is arranged at the lower part of the pre-calcining furnace 41. Figure 4 As shown, the high temperature resistant first air lock flap valve 32 of the separation unit 30 is connected to the lower part of the pre-calcining furnace 41.

[0084] Figure 5 A flow chart for cement clinker generation according to yet another exemplary embodiment of the present invention; Figure 6 is a schematic diagram of a cement clinker production system according to an exemplary embodiment of the present invention, Figure 5 The flowchart shown corresponds to the following.

[0085] Figure 5-Figure 6 The embodiment shown is Figure 1-Figure 4The embodiment shown differs in that Figure 6 In the embodiment, the pre-calcining furnace 41 is provided with a preheating air inlet D4 and a fuel inlet D5, wherein the preheating air inlet D4 and the fuel inlet D5 are both provided at the upper part of the pre-calcining furnace 41. Figure 6 As shown, the upper part of the precalcining furnace 40 supplies fuel and preheated air, and the materials and flue gas / coal gas enter the firing unit 50 from the lower part of the precalcining furnace 40. The cement materials enter the firing unit 50 for firing and then cooling, while the flue gas / coal gas returns to the decomposition unit 20 together with the flue gas of the firing unit 50.

[0086] If the pre-calcining furnace 41 is a reducing atmosphere, NOx in the high-temperature flue gas at the outlet of the calcining unit 50 can be reduced at high temperature. The existing circulation path is the decomposition unit 20 → separator 31 → pre-calcining furnace 41 → calcining unit 50 → decomposition unit 20.

[0087] Compared with the existing new dry cement production process, the total coal consumption of the calciner + rotary kiln in the present invention is reduced, the total flue gas volume is reduced, and the total heat carried by the flue gas is reduced. Although the flue gas temperature entering the decomposition furnace from the kiln tail smoke chamber and the pre-calcining furnace will increase by 100-200°C, the overall heat can be fully utilized by the decomposition furnace. The kiln tail smoke chamber can control the crusting of the flue gas by additionally introducing a small amount of raw material and combining it with purging. In addition, due to the reduction in flue gas volume, the exhaust heat loss of the system is also reduced.

[0088] Based on the above, the present invention proposes the following technical solutions:

[0089] 1. A cement clinker production system, comprising:

[0090] A preheating unit, adapted to perform preheating treatment on cement raw materials;

[0091] A decomposition unit, adapted to decompose the cement material from the preheating unit;

[0092] A separator, adapted to separate cement material from the decomposition unit;

[0093] A pre-calcining furnace, suitable for pre-calcining the cement material from the separator;

[0094] A calcining unit, suitable for calcining cement materials from the pre-calcining furnace;

[0095] a cooling unit adapted to cool the cement material from the firing unit, the cooled cement clinker being adapted to be discharged from the cooling unit,

[0096] in:

[0097] The system comprises a first circulation loop of particles and / or flue gases formed between a decomposition unit, a separator and a precalciner, particles and / or flue gases coming from the precalciner being adapted to enter the decomposition unit.

[0098] 2. The system according to item 1, wherein:

[0099] The upper flue gas outlet of the pre-calcining furnace is communicated with the lower part of the decomposition unit and the lower material outlet of the pre-calcining furnace is communicated with the sintering unit, or the pre-calcining furnace is communicated with the sintering unit only based on the lower material outlet; and / or

[0100] The smoke outlet of the burning unit is communicated with the lower part of the decomposition unit.

[0101] 3. The system according to 2, wherein:

[0102] A fuel inlet is disposed at the lower portion of the decomposition unit.

[0103] 4. The system according to 2, wherein:

[0104] The system further comprises a preheating air duct for recovering heat of clinker in the cooling unit, wherein the preheating air duct provides preheating air for the decomposition unit and / or the precalcining furnace and / or the firing unit.

[0105] 5. The system according to 2, wherein:

[0106] The fuel inlet and the air inlet of the pre-calcining furnace are arranged at the lower part of the pre-calcining furnace, and the lower outlet of the separator is communicated with the upper part of the pre-calcining furnace or with the lower part of the pre-calcining furnace; or

[0107] The fuel inlet and the air inlet of the pre-calcining furnace are arranged at the upper part of the pre-calcining furnace, and the lower outlet of the separator is communicated with the upper part of the pre-calcining furnace.

[0108] 6. The system according to item 1, wherein:

[0109] The pre-calcining furnace is suitable for being set in a reducing atmosphere.

[0110] 7. The system according to item 1, further comprising:

[0111] The air supply control unit is used to control the wind speed of the preheating air or combustion air entering the pre-calcining furnace.

[0112] 8. A system according to any one of 1 to 7, wherein:

[0113] The system further comprises a second circulation loop formed between the preheating unit, the decomposition unit and the separator; and / or

[0114] The system includes a third circulation loop formed between the decomposition unit, the separator, the pre-calcination furnace and the firing unit. 9. A method for producing cement clinker, comprising the steps of:

[0115] A preheating unit, a decomposition unit, a separator, a precalcining furnace, a burning unit and a cooling unit are provided, wherein the preheating unit is suitable for preheating the cement raw material, the decomposition unit is suitable for decomposing the cement material from the preheating unit, the separator is suitable for separating the cement material from the decomposition unit, the precalcining furnace is suitable for precalcining the cement material from the separator, the burning unit is suitable for burning the cement material from the precalcining furnace, and the cooling unit is suitable for cooling the cement material from the burning unit; and

[0116] A first circulation loop of particles and / or flue gas is formed between the decomposition unit, the separator and the precalciner, so that particles and / or flue gas from the precalciner enter the decomposition unit.

[0117] 10. The method according to 9, wherein:

[0118] The temperature of the preheat treatment is controlled below 900°C; and / or

[0119] The temperature of the decomposition treatment is controlled between 800-900°C; and / or

[0120] The temperature of the separation process is controlled between 800-900°C; and / or

[0121] The temperature of the pre-calcination treatment is controlled between 1000-1200°C; and / or

[0122] The temperature of the sintering process is controlled between 1200-1700℃.

[0123] 11. The method according to 9 further comprises the steps of:

[0124] forming a second circulation loop between the preheating unit, the decomposition unit and the separator; and / or

[0125] A third circulation loop is formed between the decomposition unit, the separator, the precalciner and the firing unit.

[0126] 12. The method according to 9 further comprises the steps of:

[0127] The heat of the clinker in the cooling unit is recovered to form preheated air, and the preheated air is provided to the decomposition unit and / or the precalcining furnace and / or the firing unit.

[0128] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for producing cement clinker, comprising: A preheating unit, adapted to perform preheating treatment on cement raw materials; A decomposition unit, adapted to decompose the cement material from the preheating unit; A separator, adapted to separate cement material from the decomposition unit; A pre-calcining furnace, suitable for pre-calcining the cement material from the separator; A calcining unit, suitable for calcining cement materials from the pre-calcining furnace; a cooling unit adapted to cool the cement material from the firing unit, the cooled cement clinker being adapted to be discharged from the cooling unit, in: The system comprises a first circulation loop of particles and / or flue gases formed between a decomposition unit, a separator and a precalciner, particles and / or flue gases coming from the precalciner being adapted to enter the decomposition unit.

2. The system of claim 1, wherein: The upper flue gas outlet of the pre-calcining furnace is communicated with the lower part of the decomposition unit and the lower material outlet of the pre-calcining furnace is communicated with the sintering unit, or the pre-calcining furnace is communicated with the sintering unit only based on the lower material outlet; and / or The smoke outlet of the burning unit is communicated with the lower part of the decomposition unit.

3. The system of claim 2, wherein: A fuel inlet is disposed at the lower portion of the decomposition unit.

4. The system of claim 2, wherein: The system further comprises a preheating air duct for recovering heat of clinker in the cooling unit, wherein the preheating air duct provides preheating air for the decomposition unit and / or the precalcining furnace and / or the firing unit.

5. The system of claim 2, wherein: The fuel inlet and the air inlet of the pre-calcining furnace are arranged at the lower part of the pre-calcining furnace, and the lower outlet of the separator is communicated with the upper part of the pre-calcining furnace or with the lower part of the pre-calcining furnace; or The fuel inlet and the air inlet of the pre-calcining furnace are arranged at the upper part of the pre-calcining furnace, and the lower outlet of the separator is communicated with the upper part of the pre-calcining furnace.

6. The system of claim 1, wherein: The pre-calcining furnace is suitable for being set in a reducing atmosphere.

7. The system of claim 1, further comprising: The air supply control unit is used to control the wind speed of the preheating air or combustion air entering the pre-calcining furnace.

8. The system according to any one of claims 1 to 7, wherein: The system further comprises a second circulation loop formed between the preheating unit, the decomposition unit and the separator; and / or The system includes a third circulation loop formed between the decomposition unit, the separator, the precalciner and the firing unit.

9. A method for producing cement clinker, comprising the steps of: A preheating unit, a decomposition unit, a separator, a precalcining furnace, a burning unit and a cooling unit are provided, wherein the preheating unit is suitable for preheating the cement raw material, the decomposition unit is suitable for decomposing the cement material from the preheating unit, the separator is suitable for separating the cement material from the decomposition unit, the precalcining furnace is suitable for precalcining the cement material from the separator, the burning unit is suitable for burning the cement material from the precalcining furnace, and the cooling unit is suitable for cooling the cement material from the burning unit; and A first circulation loop of particles and / or flue gas is formed between the decomposition unit, the separator and the precalciner, so that particles and / or flue gas from the precalciner enter the decomposition unit.

10. The method according to claim 9, wherein: The temperature of the preheat treatment is controlled below 900°C; and / or The temperature of the decomposition treatment is controlled between 800-900°C; and / or The temperature of the separation process is controlled between 800-900°C; and / or The temperature of the pre-calcination treatment is controlled between 1000-1200°C; and / or The temperature of the sintering process is controlled between 1200-1700℃.

11. The method according to claim 9, further comprising the steps of: forming a second circulation loop between the preheating unit, the decomposition unit and the separator; and / or A third circulation loop is formed between the decomposition unit, the separator, the precalciner and the firing unit.

12. The method according to claim 9, further comprising the steps of: The heat of the clinker in the cooling unit is recovered to form preheated air, and the preheated air is provided to the decomposition unit and / or the precalcining furnace and / or the burning unit.

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