Method for manufacturing cement clinker

Abstract

To provide a production method of cement clinker capable of reducing generation of CO2, and utilizing combustion gas effectively.SOLUTION: A production method of cement clinker has a raw material preparation step (S1) for preparing powder raw material by drying and pulverizing cement clinker raw material, and a calcination step (S2) for calcining the powder raw material prepared in the raw material preparation step by using a heat energy source including gaseous fuel. A using amount of gaseous fuel in the calcination step is adjusted so that a moisture content in combustion gas becomes 10 vol% or less, and drying of the cement clinker raw material in the raw material preparation step is performed by using combustion gas having a moisture content of 10 vol% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing cement clinker.

Background Art

[0002] As steps in manufacturing cement, mainly, there 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 make cement.

[0003] In the above firing step, usually, as a heat source, a carbon-containing heat energy source such as petroleum or coal is used, 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, a method of using hydrogen, methane, ethane, propane (see Patent Document 1) or a method of using ammonia (see Patent Document 2) has 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 that can reduce the amount of CO2 generated and effectively utilize combustion gases. [Means for solving the problem]

[0008] The inventors of the present invention have found that, as described above, 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 cement clinker raw materials. Therefore, they have found that limiting the amount of gaseous fuel used in the combustion process is effective in utilizing the combustion gas to dry cement clinker raw materials, 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 by adjusting the amount of gas fuel used in the firing step so that the moisture content of the generated combustion gas is 10 vol% or less, and using the combustion gas with a moisture content of 10 vol% or less to dry the cement clinker raw material in the raw material preparation step. [2] The method for producing cement clinker according to [1], characterized in that the gaseous fuel is hydrogen. [3] A method for producing cement, characterized by having a finishing step of mixing gypsum with cement clinker produced by the manufacturing method described in [1] or [2] and grinding it. [Effects of the Invention]

[0010] The present invention's method for producing cement clinker can reduce CO2 emissions and facilitate the effective use of combustion gases. [Brief explanation of the drawing]

[0011] [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. [Modes for carrying out the invention]

[0012] 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 containing gaseous fuel, wherein the amount of gaseous fuel used in the firing step is adjusted so that the moisture content of the generated combustion gas is 10 vol% or less, and the cement clinker raw materials in the raw material preparation step are dried using combustion gas with a moisture content of 10 vol% or less.

[0013] The present invention's method for producing cement clinker uses gaseous fuel as part of the heat energy source used in the firing process, thus reducing CO2 emissions compared to cases where only carbon-containing heat energy sources such as petroleum and coal are used. On the other hand, although the moisture content of the combustion gas generated in the firing process increases, since the gaseous fuel is limited to only a part of the overall heat energy source, there is no problem in using the combustion gas generated in the firing process for drying the cement material in the raw material preparation process, and the cement material can be dried in the same way as when only conventional carbon-containing heat energy sources such as petroleum and coal are used.

[0014] 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.

[0015] (Raw material preparation step) The raw material preparation step of the present invention is a step of drying and pulverizing the 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.

[0016] In the raw material preparation step, mainly, batching treatment, drying treatment, and pulverizing treatment are performed. The batching 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.

[0017] 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 utilized. That is, the combustion gas generated in the firing step can be directly introduced into a drying device for drying the cement clinker raw materials and utilized. Also, the combustion gas can be used as an indirect heating medium for an indirect heating type drying device that externally heats the cement clinker raw material storage section. Although gas fuel is used as part of the thermal energy source for the combustion gas of the present invention, its usage amount is limited to such an extent that there is no problem in drying the cement clinker raw materials. Therefore, conventionally, the cement clinker raw materials can be sufficiently dried.

[0018] (Firing step) The firing step of the present invention is a step of firing the powder raw materials prepared in the raw material preparation step using a thermal energy source containing gas fuel (step 2). For example, using a firing device such as a rotary kiln equipped with a gas burner, the powder raw materials are fired to produce cement clinker.

[0019] As a heat energy source for the combustion process, carbon-containing heat energy sources such as petroleum and coal are generally used. However, in the present invention, a gas fuel is used in part thereof. Examples of the gas fuel include hydrogen, methane, ethane, propane, ammonia, etc. Hydrogen is preferred in terms of flammability and the fact that it does not generate any CO2. By using a gas fuel as part of the heat energy source, it is possible to reduce the amount of CO2 generated by firing.

[0020] The amount of gas fuel used is adjusted so that the moisture content of the generated combustion gas is 10 vol% or less, preferably 8 vol% or less, more preferably 6% or less. From past production records, it has been confirmed that if the moisture content is 10 vol% or less, the cement clinker raw material can be sufficiently dried without problems even when directly used for the drying treatment of the cement clinker raw material.

[0021] The moisture content of the combustion gas can be measured at the gas outlet of the firing device. Based on the constant measurement results at this gas outlet, the amount of gas fuel used may be constantly adjusted, or a fixed amount of gas fuel used may be set based on the measurement results investigated in advance.

[0022] Specifically, the amount of gas fuel used is preferably 42% or less, more preferably 31% or less, and even more preferably 19% or less of the entire heat energy source in terms of heat quantity conversion. The ratio of the gas fuel can be appropriately determined in consideration of both the perspective of reducing CO2 contained in the generated combustion gas and the perspective of generating water.

[0023] As described above, according to the method for producing cement clinker of the present invention, it is possible to achieve both reduction of the amount of CO2 generated and effective utilization of the combustion gas.

[0024] Further, the method for producing cement of the present invention is characterized by having a finishing step of blending and pulverizing gypsum with the cement clinker produced by the above production method. Here, FIG. 2 is a diagram showing the steps of the method for producing cement of the present invention.

[0025] (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 step, other materials such as blast furnace slag or fly ash may be added to the cement clinker or cement mixed with gypsum as needed. [Examples]

[0026] The following are examples of the present invention, but the technical scope of the present invention is not limited thereto. We investigated the correlation between the ratio of hydrogen used to the total heat energy during the co-firing of coal and hydrogen as thermal energy sources for the firing of cement clinker raw materials, and the amount of moisture contained in the resulting combustion gas. The results are shown in Table 1.

[0027] [Table 1]

[0028] As shown in Table 1, if the hydrogen substitution rate is 42% or less (calorific value), the moisture content of the combustion gas can be reduced to 10 vol% or less. [Industrial applicability]

[0029] The present invention's method for producing cement clinker is industrially useful because it is a useful method for producing cement clinker.

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 containing hydrogen as a gaseous fuel, A method for producing cement clinker, characterized in that the amount of hydrogen used in the firing step is adjusted based on the correlation between the ratio of hydrogen used to the total heat amount during firing and the amount of water contained in the hydrogen as combustion gas generated, so that the amount of water in the combustion gas generated by the firing is 6 vol% or less, and the cement clinker raw materials in the raw material preparation step are dried using the combustion gas with a water content of 6 vol% or less.

2. A method for producing cement, characterized by having a finishing step of mixing gypsum with cement clinker produced by the manufacturing method described in claim 1 and then grinding it.

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