Coal mixing method of coal gasification combined cycle

Abstract

The present invention provides a coal mixing method of a coal gasification combined cycle, comprising determining, by a preliminary raw material determination unit, a mixing ratio of coal having different properties and a flux addition amount in a step before inputting raw materials into a gasifier. The present invention relates to a coal mixing method of a coal gasification combined cycle, comprising, by a preliminary raw material determination unit: a first step of calculating a liquidus temperature estimation value from a property database of two or more different types of coal, and an FeO triangular diagram; a second step of comparing the liquidus temperature estimation value with a liquidus temperature reference value; and a third step of determining a flux addition amount such that the liquidus temperature estimation value and the liquidus temperature reference value match.

Description

Coal blending method for combined cycle coal gasification power generation

[0001] The present invention relates to a coal blending technology for coal gasification combined cycle power generation, and more specifically, to a coal blending method for coal gasification combined cycle power generation using coal having different properties as feedstock.

[0002] Although coal is one of the raw materials with guaranteed supply stability due to its abundant and extensive global reserves, the volatility of coal prices has increased as the global supply and demand structure undergoes real-time changes driven by factors such as rising demand for thermal coal in countries like China and India, and export restrictions imposed by major coal-producing nations. Furthermore, demand from developed countries has begun to rise as the value of clean coal utilization technologies, such as the Integrated Gasification Combined Cycle (IGCC), which emits lower levels of pollutants like carbon dioxide and sulfur dioxide compared to conventional coal power generation, increases. Consequently, as coal supply volumes and costs fluctuate sensitively depending on international affairs and natural disasters, it is necessary to diversify coal sources and secure process technologies capable of maintaining a certain level of gasification efficiency to ensure the stable operation of IGCC.

[0003] Typically, in the operation process technology of a coal gasification combined cycle power plant, the fuel determination unit is characterized by determining whether to mix flux (additive) into the coal based on the gasification suitability results and providing an operation guide according to the flux input ratio. It is characterized by selecting a primary target coal from the primary coal types, analyzing plant performance while changing the mixing ratio of secondary target coals at a predetermined rate, and controlling the gasification plant after determining gasification suitability. Since low-quality syngas is produced due to the instability of the initial operation, the above control method requires an operation method suitable for the initial operation.

[0004] Furthermore, conventional technology for coal gasification combined cycle power generation, which uses a mixture of coals with different characteristics, controls the amount of flux, such as fly ash, based on the SiO2, Al2O3, and other components (FeO3, CaO) contained in the coal. Since the primary purpose of this technology is to reduce the cost of input raw materials by adding fly ash and additives, there is a need for technological development that also considers the setting of mixing ratios for coals with different characteristics.

[0005] (Prior Literature)

[0006] Korean Patent Publication No. 10-2200407

[0007] Japanese Patent Publication No. 4903623

[0008] The objective of the present invention is to provide a process control method for coal gasification combined cycle power generation using coal having different properties as feedstocks, wherein the coal mixing method for coal gasification combined cycle power generation is a method for coal gasification combined cycle power generation.

[0009] According to an embodiment of the present invention, a coal blending method for coal gasification combined cycle power generation is provided. The method may include a pre-raw material determination unit comprising: a first step of calculating an estimated liquidus temperature of the input raw material from two or more coal attribute databases and a SiO2-Al2O3-CaO triangle diagram according to FeO content in a step prior to inputting raw materials for a coal gasification combined cycle power generation gasifier; a second step of comparing the estimated liquidus temperature with a reference liquidus temperature corresponding to the gasifier operating conditions; and a third step of determining the amount of flux added so that the estimated liquidus temperature and the reference liquidus temperature match.

[0010] In addition, the above coal property database may include one or more of volatile matter, ash, higher calorific value, ash melting point, Na2O+K2O, S / A ratio (SiO2 / Al2O3 Ratio), Fe2O3, MgO, CaO content, and Silica Ratio.

[0011] In addition, the above Fe2O3+MgO+CaO content does not exceed 15% to 25%, and the above Fe2O3 among Fe2O3+MgO+CaO may include the feature of controlling Fe2O3 to 15% or less.

[0012] In addition, the coal blending process according to the above-mentioned pre-raw material determination unit may additionally include a key indicator review step.

[0013] In addition, the above-mentioned key indicator review step sets one or more of the fly ash unburned content alarm, O2 / Coal ratio, Membrane Wall Total Duty, CO2 verification, and O2 / C molar ratio as key indicators, and may further include ash content (%, DB), S / A ratio, S / A ratio (SiO2 / Al2O3 Ratio), and Na2O+K2O3 (%).

[0014] The present invention can also be provided in a form that combines various means for solving the above problem.

[0015] According to the present invention, by providing a coal blending method for combined cycle coal gasification power generation, it is expected that the efficiency of the gasifier will be improved and the quality control of the final product will be easy.

[0016] Figure 1 is a triangular diagram for calculating the liquidus temperature to explain the coal mixing method of a combined cycle coal gasification power generation according to an embodiment of the present invention.

[0017] Figure 2 is a viscosity graph before and after the addition of flux according to a viscosity calculation formula to explain the coal mixing method of a coal gasification combined cycle plant according to an embodiment of the present invention.

[0018] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0019] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0020] The above-described coal blending method includes a pre-raw material determination unit that determines the mixing ratio of coals having different properties and the amount of flux to be added at a stage prior to raw material input.

[0021] The above-mentioned pre-raw material determination unit is characterized by comprising: a first step of calculating an estimated liquidus temperature value based on a SiO2-Al2O3-CaO phase equilibrium diagram according to FeO content and a database of coal properties of two or more types; a second step of comparing the estimated liquidus temperature value with a reference liquidus temperature value corresponding to the operating conditions of the gasifier; and a third step of determining the amount of flux added so that the estimated liquidus temperature value and the reference liquidus temperature value match.

[0022] The method for calculating the liquidus temperature to determine the amount of flux added above uses the Kalmanovitch viscosity formula, and depending on the properties of the coal, it can be modified to viscosity formulas such as the Reid & Cohen, Urbain Model, S2 Corrlation, and Watt-Fereday. The properties of the coal are volatile matter, ash, higher calorific value, ash melting point, Na2O+K2O, and S / A ratio (SiO2 / Al2O3 Ratio). Additionally, it may include the content of Fe2O3, MgO, and CaO, as well as the Silica Ratio. The flux may be selected from one or more of limestone, slag fine, silica, and fly ash.

[0023] The above coal blending method may additionally include a key indicator review step in the coal blending process according to the pre-raw material determination unit. The key indicator review step is characterized by verifying the fly ash unburned content alarm, O2 / Coal ratio, Membrane Wall Total Duty, CO2 verification, and O2 / C molar ratio, and setting these as key indicators. The key indicators may further include ash content (%, DB), S / A ratio (SiO2 / Al2O3 Ratio), and Na2O+K2O3 (%). In particular, since the shape and viscosity of slag may change due to specific components such as Fe2O3, MgO, and CaO, potentially causing equipment problems, they must be controlled to a minimum of 15% and a maximum of 25%. Among the specific components such as Fe2O3, MgO, and CaO, Fe2O3 must be controlled to 15% or less. If Fe2O3 is 15% or more, the influence of Fe affects the behavior of fly ash and slag inside the facility, which may cause the Slag Tap at the bottom of the gasifier to become clogged or the Top Cone at the top to become clogged.

[0024] The allowable ranges for the above key indicators are as follows: the fly ash unburned content alarm should be at least 5%, preferably 7% or less; the O2 / C molar ratio varies depending on the characteristics of the coal, but is preferably between a minimum of 0.68 and a maximum of 0.82. The Total Heat Duty on the Membrane Wall Tube side is preferably between a minimum of 10MW and a maximum of 14MW.

[0025] To create a slag layer of appropriate thickness on the gasifier wall to protect the gasifier wall and ensure smooth slag discharge, the ash content within the coal type is preferably between a minimum of 7% and a maximum of 18%. Additionally, to ensure an appropriate viscosity of the slag layer between 50 and 250 Poise and secure the gasifier's operation window, the S / A ratio is preferably between 1.6 and 3.0. In the case of Na2O+K2O3 (%), it is preferably 4% or less to prevent fouling caused by fine particles at the downstream end of the gasifier.

[0026] According to an embodiment of the present invention, a coal blending method for coal gasification combined cycle power generation includes a preliminary raw material determination unit that determines the mixing ratio of coals having different properties and the amount of flux added in a preliminary raw material input stage. The preliminary raw material determination unit is characterized by including: a first step of calculating an estimated liquidus temperature (1) of a raw material mixed with coals having different properties from a database of two or more types of coal properties of FIG. 1 and a SiO2-Al2O3-CaO phase equilibrium diagram according to FeO content; a second step of comparing the estimated liquidus temperature with a reference value of the liquidus temperature in a database corresponding to gasifier operating conditions that can secure the efficiency of the gasifier and the quality of the final product; and a third step of determining the amount of flux added so that the reference value of the liquidus temperature and the liquidus temperature (2) with the estimated liquidus temperature are the same.

[0027] The coal property database includes the calorific value, volatile matter, elemental composition, moisture content, ash content and ash composition, and ash melting point of the coal. One or more fluxes may be selected from limestone, slag fine, silica, and fly ash. The liquidus temperature is determined by the ash composition of the raw material, which is a mixture of two or more types of coal with different properties; although it varies depending on the characteristics of the raw material, a liquidus temperature of 1350–1450°C is the range in which the efficiency of the gasifier and the quality of the final product can be ensured. If the liquidus temperature falls outside this range, the amount of flux to be added for the appropriate liquidus temperature is determined using a viscosity calculation formula.

[0028] The method for calculating the liquidus temperature to determine the amount of flux added uses the Kalmanovitch viscosity formula as shown in Figure 2, and can be changed to viscosity formulas such as Reid & Cohen, Urbain Model, S2 Correlation, and Watt-Fereday depending on the properties of the coal.

[0029] The Kalmanovitch viscosity formula is a mathematical model used to predict the viscosity of complex mixtures (e.g., multi-component solutions). The Kalmanovitch viscosity formula is as shown in (1).

[0030] -(1)

[0031] η is the total viscosity of the mixture

[0032] φ i is the mass fraction of each component (can also be expressed as mole fraction or volume fraction),

[0033] η i is the individual viscosity of each component

[0034] n is the number of components included in the mixture

[0035] The Reid & Cohen viscosity formula is a mathematical model used to predict the viscosity of complex mixtures (e.g., multi-component solutions). The Reid & Cohen viscosity formula is as shown in (2).

[0036] -(2)

[0037] η is the total viscosity of the mixture,

[0038] φ i is the mass fraction (or volume fraction) of each component,

[0039] η i is the individual viscosity of each component,

[0040] n is the number of components included in the mixture

[0041] The Urbain Model viscosity calculation formula is a mathematical model used to predict the viscosity of complex mixtures (e.g., multi-component solutions). The Urbain Model viscosity calculation formula is as shown in (3).

[0042] -(3)

[0043] η is the total viscosity of the mixture,

[0044] φ iis the mass fraction (or volume fraction) of each component,

[0045] T is the temperature of the mixture (usually absolute temperature, in Kelvin units),

[0046] T i is the boiling point of each component (the absolute temperature at which the component has no viscosity at a specific temperature),

[0047] m i is the Urbain viscosity coefficient of each component

[0048] The Watt-Fereday viscosity equation is a mathematical model used to predict the viscosity of complex mixtures (e.g., multi-component solutions). The Watt-Fereday viscosity equation is as shown in (3).

[0049] -(4)

[0050] η is the total viscosity of the mixture,

[0051] φ i is the mass fraction (or volume fraction) of each component,

[0052] η i is the individual viscosity of each component,

[0053] n is the number of components included in the mixture

[0054] After estimating the liquidus temperature with added flux, the behavior of the slag within the gasifier is predicted and evaluated to determine whether the recommended gasification temperature based on the coal property database is appropriately correlated with the corresponding liquidus temperature. At the corresponding flux input rate and gasification temperature, the average viscosity of the liquid slag on the inner wall of the gasifier should be 50 to 250 Poise, and the Total Heat Duty on the Membrane Wall Tube side should preferably be between a minimum of 10 MW and a maximum of 14 MW. Although the O2 / C molar ratio varies depending on the characteristics of the coal, it is preferable to have a ratio between a minimum of 0.68 and a maximum of 0.82, considering the equivalent ratio of carbon in the coal type to the gasifying agents, water and oxygen. If the gasifying agent is insufficient, the unburned content of fly ash and slag increases; if it is excessive, the fraction of CO2, the final oxide rather than synthesis gas, increases in the final product. Therefore, it is advisable to review the quality of the final product when the fly ash unburned content is between 5% and preferably within 7%.

[0055] Although an embodiment of the present invention has been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention.

Claims

1. In the stage prior to feeding the raw material into the gasifier of a coal gasification combined cycle power generation, Step 1: Calculating an estimated liquidus temperature of the input raw material from a coal attribute database and an FeO triangle diagram; A second step of comparing the above estimated liquidus temperature value with a reference liquidus temperature value corresponding to the gasifier operating conditions; A coal blending method for coal gasification combined cycle power generation comprising a preliminary raw material determination unit including a third step of determining the amount of flux added so that the estimated liquidus temperature value and the reference liquidus temperature value match.

2. In Paragraph 1, A coal mixing method for combined cycle coal gasification power generation, characterized in that the above coal attribute database includes volatile matter, ash, higher calorific value, ash melting point, Na2O+K2O, S / A ratio, and Fe2O3+MgO+CaO ratio.

3. In Paragraph 2, A coal mixing method for coal gasification combined cycle power generation, characterized in that the above Fe2O3+MgO+CaO content does not exceed a minimum of 15% to a maximum of 25%, and the Fe2O3 in the above Fe2O3+MgO+CaO is controlled to 15% or less.

4. A coal blending method for coal gasification combined cycle power generation, characterized in that, in the first paragraph, the coal blending process according to the above-mentioned pre-raw material determination unit additionally includes a major indicator review step.

5. A coal mixing method for coal gasification combined cycle power generation, characterized in that the above-mentioned main indicator review step is set as verifying fly ash unburned content alarm, O2 / Coal ratio, Membrane Wall Total Duty, CO2 verification, and O2 / C molar ratio as main indicators, and may further include ash content (%, DB), S / A ratio, and Na2O+K2O3 (%).

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