Method and equipment for manufacturing cement clinker

Abstract

To provide a production method of cement clinker capable of reducing generation of CO2, and effectively utilizing combustion gas.SOLUTION: A production method of cement clinker has a raw material preparation step (step 1) for preparing powder raw material by drying and pulverizing cement clinker raw material, and a calcination step (step 2) for calcining the powder raw material prepared in the raw material preparation step by using a heat energy source including gaseous fuel. Drying of the cement clinker raw material in the raw material preparation step is performed by indirect heat treatment utilizing heat energy of combustion gas generated in the calcination step.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a method and equipment for manufacturing cement clinker.

Background Art

[0002] When manufacturing cement, the main steps are a raw material preparation step of drying and pulverizing cement clinker raw materials such as limestone and clay, a firing step of firing the prepared cement clinker raw materials in a firing device such as a rotary kiln to produce cement clinker, and a finishing step of adding gypsum or the like to the produced cement clinker to obtain cement.

[0003] In the above firing step, usually, a carbon-containing heat energy source such as oil or coal is used as the heat source, and there is a problem that a large amount of CO2 is generated during combustion. Therefore, in order to reduce the amount of CO2 generated, it has been proposed to use a gas fuel with a low CO2 generation amount as the main heat energy source.

[0004] For example, as a gas fuel, methods using hydrogen, methane, ethane, propane (see Patent Document 1) or ammonia (see Patent Document 2) have been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Compared to using carbon-containing thermal energy sources such as petroleum and coal, using gaseous fuels such as hydrogen and methane reduces CO2 emissions, but increases water emissions. Since the combustion gases generated in the firing process are usually used as a heat source for drying cement clinker raw materials in the raw material preparation process, too much moisture in the combustion gases can hinder the drying of the cement clinker raw materials.

[0007] The object of the present invention is to provide a method for producing cement clinker and a manufacturing facility that can reduce the amount of CO2 generated and effectively utilize combustion gases. [Means for solving the problem]

[0008] As described above, the inventors have found that using gaseous fuel in the firing process to reduce CO2 generation increases water generation, which can cause problems when using the combustion gas to dry the cement clinker raw material. Therefore, they have found that it is effective to use the combustion gas as an indirect heating medium rather than directly heating the cement clinker raw material with the combustion gas to dry it, and have completed the present invention.

[0009] In other words, the present invention is as follows: [1] A method for producing cement clinker, comprising a raw material preparation step of drying and pulverizing cement clinker raw materials to prepare powdered raw materials, and a firing step of firing the powdered raw materials prepared in the raw material preparation step using a thermal energy source including gaseous fuel, A method for producing cement clinker, characterized in that the drying of the cement clinker raw materials in the raw material preparation step is carried out by indirect heat treatment utilizing the thermal energy of the combustion gas generated in the firing step. [2] A method for producing cement clinker according to [1], characterized in that outside air heated by the combustion gas is introduced into a drying apparatus for drying cement clinker raw materials, thereby drying the cement clinker raw materials. [3] The method for producing cement clinker according to [1], characterized in that the combustion gas is used as an indirect heating medium in an indirect heating drying apparatus for drying cement clinker raw materials to dry the cement clinker raw materials. [4] A method for producing cement clinker according to any one of [1] to [3], characterized in that the gaseous fuel is hydrogen. A method for producing cement, characterized by having a finishing step of mixing gypsum with cement clinker produced by any of the manufacturing methods described in [5] [1] to [4] and then grinding it.

[0010] [6] A cement clinker manufacturing apparatus comprising a drying apparatus for drying cement clinker raw materials, a grinding apparatus for grinding the cement clinker raw materials dried in the drying apparatus, and a firing apparatus for firing the powdered raw materials ground in the grinding apparatus, A cement clinker manufacturing apparatus characterized in that the drying apparatus indirectly utilizes the thermal energy of the combustion gas generated in the firing apparatus to perform drying. [7] A cement clinker manufacturing apparatus according to [6], comprising a heat exchanger connected to the firing apparatus and the drying apparatus, wherein the heat exchanger heats outside air with combustion gas generated in the firing apparatus and introduces the heated outside air into the drying apparatus. [8] The cement clinker manufacturing apparatus according to [6], characterized in that the drying apparatus is an indirect heating type drying apparatus that heats the cement clinker raw material storage section from the outside, and uses the combustion gas generated in the firing apparatus as an indirect heating medium. [Effects of the Invention]

[0011] The present invention provides a method for producing cement clinker and a manufacturing facility that can reduce CO2 emissions and effectively utilize combustion gases. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the steps for the method of producing cement clinker according to the present invention. [Figure 2]This figure shows the steps of the cement manufacturing method of the present invention. [Figure 3] This figure shows a cement clinker manufacturing facility (configuration A) according to one embodiment of the present invention. [Figure 4] This figure shows a cement clinker manufacturing facility (configuration B) according to another embodiment of the present invention. [Modes for carrying out the invention]

[0013] The present invention provides a method for producing cement clinker, comprising a raw material preparation step of drying and pulverizing cement clinker raw materials to prepare powdered raw materials, and a firing step of firing the powdered raw materials prepared in the raw material preparation step using a thermal energy source including gaseous fuel, characterized in that the drying of the cement clinker raw materials in the raw material preparation step is carried out by indirect heating treatment utilizing the thermal energy of the combustion gas generated in the firing step.

[0014] Here, indirect heat treatment refers to a heat treatment process in which the combustion gas does not come into direct contact with the cement clinker raw material to be dried. For example, this could involve heating another substance with the combustion gas and then directly or indirectly drying the cement clinker raw material with that heated substance, or indirectly drying the cement clinker raw material by heating a container containing the cement clinker raw material from the outside with the combustion gas.

[0015] The present invention's method for producing cement clinker uses gaseous fuel as the thermal energy source in the firing process, thus reducing CO2 emissions compared to using only carbon-containing thermal energy sources such as petroleum and coal. On the other hand, although the moisture content of the combustion gas generated in the firing process increases, the thermal energy of the combustion gas is used indirectly rather than directly for drying the cement material in the raw material preparation process. Therefore, there is no hindrance to drying the cement material, and sufficient drying can be achieved, similar to when using only conventional carbon-containing thermal energy sources such as petroleum and coal.

[0016] The following will specifically describe each step. Here, FIG. 1 is a diagram showing the steps of the method for manufacturing cement clinker of the present invention.

[0017] (Raw material preparation step) The raw material preparation step of the present invention is a step of drying and pulverizing cement clinker raw materials to prepare powder raw materials (step 1). Here, as the cement clinker raw materials, conventionally known general cement clinker raw materials such as limestone, clay, and silica can be used.

[0018] In the raw material preparation step, mainly, blending treatment, drying treatment, and pulverizing treatment are performed. The blending treatment is a treatment of blending various cement clinker raw materials in a predetermined ratio according to the purpose. The drying treatment is a treatment of heating and drying the cement clinker raw materials for each raw material or in a blended (mixed) state. The pulverizing treatment is a treatment of pulverizing the dried cement clinker raw materials, and it may be performed simultaneously with the drying treatment. The drying treatment can be performed before and / or simultaneously with the pulverizing treatment.

[0019] In the drying treatment of the raw material preparation step of the present invention, the thermal energy of the combustion gas generated in the firing step is indirectly utilized. That is, the combustion gas is heat-treated without directly contacting the cement clinker raw materials to be dried. According to the present invention, since gas fuel is used in the firing step, the combustion gas contains a large amount of moisture, but since this combustion gas is not directly contacted with the cement clinker raw materials to be dried, the adverse effects of moisture are prevented, and the cement clinker raw materials can be sufficiently dried as in the prior art.

[0020] Specifically, a mode (hereinafter sometimes referred to as method A) of introducing the outside air heated by the combustion gas into the drying device for drying the cement clinker raw materials to dry the cement clinker raw materials can be cited. Also, a mode (hereinafter sometimes referred to as method B) of using the combustion gas as a heating medium of an indirect heating type drying device for drying the cement clinker raw materials to dry the cement clinker raw materials can be cited.

[0021] (Firing step) The calcination process of the present invention is a process of calcining the powdered raw material prepared in the raw material preparation process using a thermal energy source including gaseous fuel (Step 2). For example, the powdered raw material is calcined using a calcination apparatus such as a rotary kiln equipped with a gas burner to produce cement clinker.

[0022] While carbon-containing thermal energy sources such as petroleum and coal are generally used as thermal energy sources in the combustion process, this invention uses gaseous fuels in part or all of the process. Examples of gaseous fuels include hydrogen, methane, ethane, propane, and ammonia, but hydrogen is preferred due to its flammability and the fact that it does not generate any CO2. By using gaseous fuels as thermal energy sources, the amount of CO2 generated during firing can be reduced.

[0023] The amount of gas fuel used is preferably 1-100% of the total thermal energy source in terms of heat energy, more preferably 5-90%, and even more preferably 10-80%. The proportion of gas fuel can be appropriately determined taking into consideration both the reduction of CO2 contained in the combustion gases generated and the generation of water.

[0024] The moisture content of the combustion gas can be measured, for example, at the gas outlet of the firing apparatus. Based on the continuous measurement results at this gas outlet, the amount of gas fuel used may be adjusted on a regular basis, or a fixed amount of gas fuel may be used based on measurement results investigated in advance.

[0025] As described above, the method for producing cement clinker according to the present invention makes it possible to achieve both a reduction in CO2 generation and effective utilization of combustion gases.

[0026] Furthermore, the present invention's method for producing cement is characterized by having a finishing step of mixing gypsum with the cement clinker produced by the above-described method and then grinding it. Here, Figure 2 is a diagram showing the steps of the present invention's method for producing cement.

[0027] (Finishing process) In the finishing process, the cement clinker prepared in steps 1 and 2 is mixed with at least gypsum and ground to produce cement (step 3). In this process, other materials such as blast furnace slag or fly ash may be added to the cement clinker or cement mixed with gypsum, as needed.

[0028] Next, we will describe the manufacturing equipment for the cement clinker of the present invention. The cement clinker manufacturing equipment of the present invention comprises a drying device for drying cement clinker raw materials, a grinding device for grinding the cement clinker raw materials dried in the drying device, and a firing device for firing the powdered raw materials ground by the grinding device, wherein the drying device indirectly utilizes the thermal energy of the combustion gas generated in the firing device to perform drying. The drying device and the grinding device in the present invention may be configured as an integrated unit (performing drying and grinding simultaneously). The manufacturing method for cement clinker according to the present invention can be carried out using the manufacturing equipment of the present invention.

[0029] Specifically, the cement clinker manufacturing equipment of the present invention may include, for example, a heat exchanger connected to a firing apparatus and a drying apparatus, wherein the heat exchanger uses combustion gas generated in the firing apparatus to heat outside air and introduces the heated outside air into the drying apparatus (hereinafter sometimes referred to as configuration A). The heat exchanger may be of any type, such as plate type or tube type, as long as it is capable of heat exchange. Method A of the manufacturing method of the present invention can be carried out with an apparatus of this configuration.

[0030] Furthermore, the cement clinker manufacturing equipment of the present invention may also be configured such that the drying apparatus is an indirect heating type drying apparatus that heats the cement clinker raw material storage section from the outside, and uses the combustion gas generated in the firing apparatus as an indirect heating medium (hereinafter sometimes referred to as configuration B). Method B of the manufacturing method of the present invention can be carried out with the apparatus of this configuration.

[0031] The manufacturing equipment for cement clinker according to the present invention will be described below with reference to the drawings. Figure 3 shows a cement clinker manufacturing facility (configuration A) according to one embodiment of the present invention.

[0032] As shown in Figure 3, the cement clinker manufacturing equipment 10 according to one embodiment of the present invention includes a drying device 11 for drying the cement clinker raw material and a firing device 12 for firing the powdered raw material obtained by crushing the dried cement clinker raw material. Note that in Figure 3, for the sake of explanation, the crushing device for crushing the dried cement clinker raw material is omitted.

[0033] The drying apparatus 11 is equipped with a raw material storage section for storing cement clinker raw materials, and heated gas (heated outside air, described later) is introduced into the raw material storage section to dry the cement clinker raw materials.

[0034] The firing apparatus 12 includes a preheater section 13 for preheating the introduced cement clinker raw material and a rotary kiln 14 for firing the cement clinker raw material. A burner 15 is provided at the outlet side of the rotary kiln 14. The cement clinker raw material (powdered raw material) introduced into the firing apparatus 12 is fired as it moves through the preheater section 13 and the rotary kiln 14.

[0035] Furthermore, the manufacturing equipment 10 is equipped with a heat exchanger 16. The heat exchanger 16 is connected to the firing apparatus 12 and the drying apparatus 11. The heat exchanger 16 introduces combustion gas generated in the firing apparatus 12 as a heating medium, and also introduces outside air, heating the outside air with the combustion gas, and then directly introduces this heated outside air into the drying apparatus 11. Since the heated outside air does not contain any moisture that would hinder drying, the cement clinker raw material in the drying apparatus 12 is efficiently dried by this heated outside air.

[0036] The heated outside air introduced into the drying apparatus 11 is discharged through the dust collector 17. Similarly, the combustion gas introduced into the heat exchanger 16 is also discharged through the dust collector 18.

[0037] Next, using Figure 4, we will describe a cement clinker manufacturing facility (configuration B) according to another embodiment of the present invention.

[0038] As shown in Figure 4, the cement clinker manufacturing equipment 20 according to another embodiment of the present invention includes a drying device 21 for drying the cement clinker raw material and a firing device 22 for firing the powdered raw material obtained by crushing the dried cement clinker raw material. Note that in Figure 4, for the sake of explanation, the crushing device for crushing the dried cement clinker raw material is omitted.

[0039] The firing apparatus 22 includes a preheater section 23 for preheating the introduced cement clinker raw material and a rotary kiln 24 for firing the cement clinker raw material. A burner 25 is provided at the outlet side of the rotary kiln 24. The cement clinker raw material (powdered raw material) introduced into the firing apparatus 22 is fired as it moves through the preheater section 23 and the rotary kiln 24.

[0040] In this embodiment, the drying apparatus 21 is characterized by being an indirect heating method rather than a direct heating method (a method in which the heating medium is directly in contact with the cement clinker raw material). That is, the drying apparatus 21 is an indirect heating device that supplies combustion gas to an external heating space of the raw material storage section, and transmits the thermal energy from the external heating space into the raw material storage section via the peripheral wall of the raw material storage section, thereby heating the inside of the raw material storage section. Outside air is supplied to the raw material storage section of the drying apparatus 21. As a result, the combustion gas, which contains a lot of moisture, does not come into direct contact with the cement clinker raw material to be dried, so that drying is not hindered and the cement clinker raw material in the drying apparatus 12 is dried efficiently.

[0041] The heated outside air and combustion gases introduced into the drying apparatus 21 are discharged through dust collectors 26 and 27. [Industrial applicability]

[0042] The present invention provides a method and equipment for producing cement clinker, and is therefore industrially useful as a method and equipment for producing cement clinker. [Explanation of symbols]

[0043] 10. Manufacturing facilities for cement clinker 11 Drying equipment 12. Firing apparatus 13 Preheater section 14 Rotary Kiln 15 burners 16 Heat exchanger 17 Dust collector 18 Dust collector 20. Manufacturing facilities for cement clinker 21 Drying equipment 22. Firing apparatus 23 Preheater section 24 Rotary Kiln 25 burners 26 Dust collector 27 Dust collector

Claims

1. A method for producing cement clinker, comprising: a raw material preparation step of drying and pulverizing cement clinker raw materials to prepare powdered raw materials; and a firing step of firing the powdered raw materials prepared in the raw material preparation step using a thermal energy source including gaseous fuel, A method for producing cement clinker, characterized in that the drying of the cement clinker raw materials in the raw material preparation step is carried out by outside air heated by an indirect heat treatment utilizing the thermal energy of the combustion gas generated in the firing step.

2. The method for producing cement clinker according to claim 1, characterized in that outside air heated by a heat exchanger using the combustion gas is introduced into a drying apparatus for drying cement clinker raw materials, thereby drying the cement clinker raw materials.

3. The method for producing cement clinker according to claim 1, characterized in that the combustion gas is used as an indirect heating medium in an indirect heating drying apparatus for drying cement clinker raw materials, and the outside air introduced into the indirect heating drying apparatus is heated to dry the cement clinker raw materials.

4. A method for producing cement clinker according to any one of claims 1 to 3, characterized in that the gaseous fuel is hydrogen.

5. A method for producing cement, characterized by having a finishing step of mixing gypsum with cement clinker produced by the manufacturing method described in any one of claims 1 to 4 and then grinding it.

6. A cement clinker manufacturing facility comprising a drying apparatus for drying cement clinker raw materials, a grinding apparatus for grinding the cement clinker raw materials dried in the drying apparatus, and a firing apparatus for firing the powdered raw materials ground in the grinding apparatus using a thermal energy source including gas fuel, A cement clinker manufacturing apparatus characterized in that the drying apparatus dries the clinker using outside air heated by an indirect heating treatment that utilizes the thermal energy of the combustion gas generated in the firing apparatus.

7. The cement clinker manufacturing apparatus according to claim 6, comprising a heat exchanger connected to the firing apparatus and the drying apparatus, wherein the heat exchanger heats outside air with combustion gas generated in the firing apparatus and introduces the heated outside air into the drying apparatus.

8. The cement clinker manufacturing equipment according to claim 6, wherein the drying apparatus is an indirect heating type drying apparatus that introduces outside air into the cement clinker raw material storage section and heats the cement clinker raw material storage section from the outside, and uses the combustion gas generated in the firing apparatus as an indirect heating medium.

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