EVALUATION METHOD FOR ADHESION INHIBITORS OF ABU

Abstract

An evaluation method for an ash adhesion inhibitor used in this combustion apparatus includes: a step of heating a fuel containing a volatile component at a first temperature to obtain a first incinerated ash containing a volatile component; a high-temperature treatment step of heating a mixture of the first incinerated ash and the ash adhesion inhibitor at a second temperature higher than the first temperature; a contact step of contacting the gas produced in the high-temperature treatment step with a first object made of quartz; and an evaluation step of evaluating the ash adhesion inhibitor based on the degree of devitrification present on the first object in the contact step.

Description

Description of EVALUATION METHOD FOR ADHESION INHIBITORS OF ABU Invention Engineering Field The present invention relates to an evaluation method for ash adhesion inhibitors. This application claims priority under Japanese Patent Application No. 2021-140564 filed with the Japan Patent Office on August 31, 2021, the contents of which are incorporated herein by reference. Background of the Invention When ash produced from fuel combustion adheres to equipment that is a combustion device (for example, a boiler or furnace), heat transfer in the equipment can be hampered, or the equipment can corrode. Patent Document 1 describes a method for supplying, into a boiler flue gas path, a corrosion inhibitor having the property of attracting corrosive particles in boiler combustion ash to inhibit corrosion due to adhesion of ash to heat transfer tubes provided in the boiler flue gas path. In the method described in Patent Document 1, corrosion of heat transfer tubes is inhibited by supplying a corrosion inhibitor into the flue gas path to bind corrosive particles in combustion ash to the corrosion inhibitor, and reduce the contact area between the corrosive particles and the heat transfer tubes when ash containing corrosive particles adheres to the heat transfer tubes. List of Citations Patent Documents Patent Document 1: WO 2014 / 192313 A Brief Description of the Invention Technical Problems The use of chemical substances (ash adhesion inhibitors) to inhibit ash adhesion can inhibit ash adhesion to equipment that is a combustion equipment, and thus can inhibit the inhibition of heat transfer and corrosion of equipment caused by ash adhesion. If the effect of ash adhesion inhibition by ash adhesion inhibitors can be evaluated by simple techniques, then this is useful for selecting ash adhesion inhibitors according to the type of fuel, determining the amount of ash adhesion inhibitor use, and the like. In view of the above circumstances, the object of at least one embodiment of the present invention is to provide an evaluation method for an ash adhesion inhibitor that can evaluate the effect of an ash adhesion inhibitor by a simple method. Solution to the Problem An evaluation method for an ash adhesion inhibitor according to at least one embodiment of the present invention is an evaluation method for an ash adhesion inhibitor used in a combustion apparatus. The evaluation method includes the step of heating a fuel containing a volatile component at a first temperature to obtain a first incinerated ash containing a volatile component, a high temperature treatment step for heating a mixture of the first incinerated ash and the ash adhesion inhibitor at a second temperature higher than the first temperature, a contact step for contacting the gas produced in the high temperature treatment step with a first object made of quartz, and an evaluation step for evaluating the ash adhesion inhibitor based on the degree of devitrification present on the first object in the contact step. Benefits of Invention In accordance with at least one embodiment of the present invention, an evaluation method for an ash adhesion inhibitor that can evaluate the effect of an ash adhesion inhibitor by a simple method is provided. Short Description of Image Figure 1 is a schematic diagram of an example combustion apparatus. Figure 2 is a flowchart of an evaluation method for an ash adhesion inhibitor according to one embodiment. Figure 3 is a photograph illustrating an example of a quartz tube encompassing a devitrification area. Figure 4 is a graph showing an example of the quantity reduction ratio during high temperature heat treatment of the first incinerated ash. Figure 5 is a table showing an example of the composition of the first incinerated ash. Complete Description of the Invention Some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, or the like of components described as embodiments or illustrated in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Combustion Equipment Configuration Example Figure 1 is a schematic diagram of an example combustion apparatus using an ash adhesion inhibitor applied by an evaluation method in accordance with several embodiments. The combustion apparatus (100) illustrated in Figure 1 includes a boiler (10) whose primary fuel is a solid fuel. The boiler (10) of this embodiment is a boiler that can burn, with a burner, pulverized fuel obtained by pulverizing solid fuel and perform heat exchange of the heat generated by this combustion with feed water or steam to produce superheated steam. As a solid fuel, biomass fuel, waste fuel, coal, or the like are used alone or in combination. The boiler (10) includes a combustion furnace (11), a combustion device (20), and a combustion gas passage (12). The combustion furnace (11) has a rectangular tubular hollow shape and is installed along a vertical direction. The combustion furnace wall (101) which is an inner wall surface of the combustion furnace (11) includes a plurality of heat transfer tubes and fins connecting the heat transfer tubes, recovers the heat generated by the combustion of the pulverized fuel by conducting heat exchange with water and steam flowing in the heat transfer tubes, and inhibits the temperature rise of the combustion furnace wall (101). A combustion device (20) is installed in the lower region of the combustion furnace (11). In this embodiment, the combustion device (20) includes a plurality of burners (21A, 21B, 21C, 21D, 21E, and 21F) (hereinafter collectively referred to as burners (21) in some cases) installed on the walls of the combustion furnace (101). The burners (21) are placed at equal intervals along the circumferential direction of the combustion furnace (11) (e.g., four burners are installed at each corner section of the combustion furnace (11) having a rectangular shape) as a set, and are arranged in a plurality of steps along the vertical direction. Note that for ease of illustration, Figure 1 illustrates only two burners in a set, and reference marks (21A, 21B, 21C, 21D, 21E, and 21F) are given for each set. The shape of the combustion furnace, the number of burner stages, the number of burners in one stage, the arrangement of burners, and the like are not limited to this embodiment. The burners (21)A, 21B, 21C, 21D, 21E, and 21F are coupled to a fuel supply section (31A, 31B, 31C, 31D, 31E, and 31F) (hereinafter, collectively referred to as the fuel supply section (31) in some cases) through a plurality of pulverized fuel pipes (22A, 22B, 22C, 22D, 22E, and 22F) (hereinafter, collectively referred to as the pulverized fuel pipes (22) in some cases), respectively. The fuel supply section (31) may include a grinder (pulverizer) for pulverizing the solid fuel. The grinder, for example, is a vertical roller grinder in which a grinding table (not illustrated) is supported in it so that it can be rotated, and a number of grinding rollers (not illustrated) are supported on the grinding table so that it can rotate together with the rotation of the grinding table.The solid fuel pulverized by the cooperation between the grinding roller and the grinding table is conveyed to the classifier (not illustrated) enclosed in the grinder by the primary air (carrier gas, oxidizer gas) supplied to the grinder. The classifier classifies the fuel into pulverized fuel having a particle size equal to or less than the particle size suitable for combustion in the burner (21) and coarse powdered fuel having a particle size larger than that particle size. The pulverized fuel passes through the classifier and is supplied to the burner (21) through the pulverized fuel pipe (22) together with the primary air. The coarse powdered fuel that does not pass through the classifier falls onto the grinding table due to its own weight in the grinder and is repulverized. A wind box (air register) (23) is provided outside the combustion furnace (11) at the installation position of the burner (21), and one end of the air duct (24) is coupled to the wind box (23). A forced-pressure fan (FDF) (32) is coupled to the other end of the air duct (24). The air supplied from the forced-pressure fan (32) is heated by the air preheater (42) installed in the air duct (24), which is supplied as secondary air (combustion air, oxidizing gas) to the burner (21) through the wind box (23), and fed into the combustion furnace (11). The combustion gas passage (12) is coupled to the top vertically of the combustion furnace (11). As a heat exchanger for recovering heat from the combustion gas, the combustion gas passage (12) is provided with superheaters (102A, 102B, and 102C) (hereinafter, collectively referred to as the superheater (102) in some cases), reheaters (103)A and 103B (hereinafter, collectively referred to as the reheater (103) in some cases), and economizers (104), and heat exchange is carried out between the combustion gas generated in the combustion furnace (11) and the feed water or steam flowing in each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to the shape illustrated in Figure 1. The flue gas duct (13), through which the combustion gases are discharged subjected to heat recovery by the heat exchanger, is coupled to the downstream side of the combustion gas path (12). An air preheater (air heater) (42) is provided between the flue gas duct (13) and the air duct (24), and carries out heat exchange between the air flowing through the air duct (24) and the combustion gases flowing through the flue gas duct (13), and heats the primary air supplied to the fuel supply section (31) (e.g., the grinder described above) and the secondary air supplied to the burner (21) so as to further carry out heat recovery from the combustion gases after heat exchange with water or steam. The exhaust gas duct (13) may be equipped with a DeNox (nitrogen oxide (NOx) removal) device (43) at a position on the upstream side relative to the air preheater (42). The DeNox device (43) supplies a reducing agent having the action of reducing nitrogen oxides such as ammonia and urea water to the combustion gas flowing through the exhaust gas duct (13), and promotes the reaction between the nitrogen oxides (NOx) in the supplied combustion gas with the reducing agent and the reducing agent through the catalysis of the DeNox catalyst installed on the DeNox device (43) so as to remove and reduce the nitrogen oxides in the combustion gas. The gas duct (41) is coupled to the exhaust gas duct (13) on the downstream side relative to the air preheater (42).The gas duct (41) is equipped with environmental devices such as a precipitator (44) such as an electrostatic precipitator that removes ash and the like in the combustion gas and a desulfurizer or desulfurizer (46) that removes sulfur oxides, and an induced draft fan (IDF) 45 to direct the flue gas to these environmental devices. The downstream end of the gas duct (41) is coupled to a chimney (47), and the combustion gas treated by the environmental devices is discharged outside the system as flue gas. In the boiler (10), fuel (e.g., pulverized fuel pulverized by a grinder and classified) from the fuel supply section (31) is supplied to the burner (21) via the pulverized fuel pipe (22) together with primary air. Secondary air heated by the air preheater (42) is supplied from the air duct (24) to the burner (21) via the wind box (23). The burner (21) blows, into the combustion furnace (11), the pulverized fuel-air mixture in which the pulverized fuel and primary air are mixed, and blows secondary air into the combustion furnace (11). The pulverized fuel-air mixture blown into the combustion furnace (11) ignites and reacts with the secondary air to form a flame. The flame forms in the lower region in the combustion furnace (11), and the high-temperature combustion gases rise in the combustion furnace (11) and flow into the combustion gas path (12).Note that in this embodiment, air is used as the oxidizing gas (primary air, secondary air), but one having an oxygen ratio greater than or less than the air ratio can be used, and stable combustion is achieved in the combustion furnace 11 by adjusting the ratio of the amount of oxygen to the amount of fuel supplied to an appropriate range. After performing heat exchange with water or steam in the superheater (102), reheater (103), and economizer (104) arranged in the combustion gas path (12), the combustion gas flowing into the combustion gas path (12) is discharged to the flue gas duct (13). Nitrogen oxides are removed in the DeNox device (43), and the combustion gas exchanges heat with primary air and secondary air in the air preheater (42), and is then further discharged to the gas duct (41). Ash and the like are removed in the precipitator (44). Sulfur oxides are removed in the desulfurizer (46), and then the combustion gas is discharged from the flue (47) to the outside of the system. Note that the heat exchanger in the combustion gas path (12) and the devices in the flue gas duct (13) to the gas duct (41) are not always arranged in the order described above with respect to the combustion gas flow. In the embodiment described above, the boiler according to the present invention is described as a boiler using solid fuel as fuel. The solid fuel used in the boiler includes coal, biomass fuel, petroleum coke (PC) fuel, petroleum residue, or the like. Note that boiler fuel is not limited to solid fuels, but can be liquid fuels such as petroleum, heavy oil, light oil, and heavy fuels, as well as factory waste fluids. Fuel gases such as natural gas, various petroleum gases, by-product gases produced in the iron-making process, and the like can also be used. Furthermore, the present invention can also be applied to multi-fuel boilers that use these various fuels in combination. The fuel supplied from the fuel supply section (31) to the combustion furnace (11) may be a fuel containing alkali metals (e.g., sodium (Na) or potassium (K)) or heavy metals (e.g., zinc (Zn) or lead (Pb)). The fuel may be a biomass fuel containing biomass or a waste fuel containing waste such as municipal waste and building materials. The fuel may be coal, or it may be a blended fuel containing two or more biomass, waste, or coal. In the combustion furnace (11), combustion gases and ash are generated by the combustion of fuel. Part of the ash accumulates at the bottom of the combustion furnace (11) and is discharged outside the combustion furnace (11) through an ash discharge section not illustrated. Another part of the ash is directed, as fly ash, into the fuel gas passage 12 and the flue gas duct (13) that accompanies the combustion gases. The ash adhesion inhibitor applied by the evaluation method according to some embodiments may be supplied to the combustion furnace (11) from the fuel supply section (31) or the like together with the fuel in the combustion apparatus (100), or the ash adhesion inhibitor may be supplied to a position (e.g., in the combustion furnace (11), the combustion gas path (12), or the flue gas duct (13)) that is different from the fuel supply position. Flowchart of the Evaluation Method for Ash Adhesion Inhibitor Next, an evaluation method for an ash adhesion inhibitor according to some embodiments will be described with reference to Figure 2. Figure 2 is a flowchart of an evaluation method for an ash adhesion inhibitor according to one embodiment. In the evaluation method for ash adhesion inhibitors shown in the flow chart shown in Figure 2, firstly, the fuel containing volatile components is heated at a first temperature to obtain the first incinerated ash containing volatile components such as alkali metal compounds or heavy metal compounds (S2). The fuel containing volatile components used in step S2 is the fuel assumed to be used in the combustion apparatus together with the ash adhesion inhibitor of the evaluation target. The volatile components contained in the fuel are those that are the factors by which the ash produced when the fuel is burned adheres to the apparatus (e.g., the heat transfer tubes that constitute the superheater (102), reheater (103), or economizer (104) described above, or the heat transfer tubes that constitute the furnace wall (101)) of the combustion apparatus. The volatile components may contain compounds of metallic elements. Examples of volatile components include alkali metals (e.g., sodium (Na) or potassium (K) compounds) or heavy metals (e.g., zinc (Zn) or lead (Pb) compounds).Examples of fuels that produce relatively high amounts of alkali metal compounds as volatile components include biomass fuels containing biomass (e.g., woody biomass). Examples of fuels that produce relatively high amounts of heavy metal compounds as volatile components include waste fuels containing waste (e.g., waste plastics, municipal waste, or building materials). The first temperature in step S2 is the temperature at which the fuel can be heated, while the volatilization of volatile components contained in the fuel is inhibited to obtain incinerated ash retaining volatile components. By heating the fuel at the first temperature to obtain the first incinerated ash containing volatile components, the effect (i.e., the inhibition effect of ash adhesion in the combustion apparatus) of inhibiting alkali metal volatilization during fuel combustion by ash adhesion inhibitor can be precisely evaluated by performing the next steps (high temperature treatment, contact, and evaluation steps). Note that the first temperature does not always refer to the temperature at a single point. That is, during fuel heating in step S2, the first temperature can vary within a certain temperature range (e.g., within a range of several degrees Celsius to several tens of degrees Celsius). When the fuel is a biomass fuel, the first temperature can be equal to or greater than 500 °C and equal to or less than 650 °C. When the fuel is a waste fuel, the first temperature can be equal to or greater than 500 °C and equal to or less than 650 °C. Next, the mixture of the first incinerated ash obtained in step S2 and the ash adhesion inhibitor is heated at a second temperature higher than the first temperature (S4; high temperature treatment step). In step S4, by heating the first incinerated ash at a temperature close to the temperature of the combustion equipment, the reaction between the incinerated ash and the ash adhesion inhibitor that occurs in the combustion equipment is simulated. The ash adhesion inhibitor used in step S4 has the function of inhibiting the volatilization of volatile components during fuel combustion in the combustion equipment. When the fuel used in step S2 contains alkali metal elements as volatile components, or when the fuel used in step S2 is a biomass fuel, the ash adhesion inhibitors described above may be, for example, aluminosilicates such as kaolinite, halloysite, or bentonite, or silica. When the fuel used in step S2 contains heavy metal elements as volatile components or when the fuel used in step S2 is waste fuel, the ash adhesion inhibitors described above may be, for example, sulfur-containing substances. The sulfur-containing substances may be sulfur or sulfur compounds. The sulfur compounds may be, for example, sulfuric acid-containing substances such as sulfuric acid or fuming sulfuric acid, or sulfates such as iron sulfate, aluminum sulfate, ammonium sulfate, or ammonium hydrogen sulfate. The second temperature in step S4 is a high temperature that approximates the temperature at a location where ash adhesion problems may occur (e.g., the position of the heat transfer tubes constituting the superheater (102), reheater (103), or economizer (104) described above and the heat transfer tubes constituting the kiln wall (101) described above) or a position on the upstream side thereof in the kiln apparatus, and is a temperature at which the perfect quality of the quartz object used in step S6 described later can be guaranteed (e.g., a temperature at which devitrification due to high temperature is less likely to occur). The second temperature may, for example, be equal to or greater than 1300 °C and equal to or less than 1500 °C. Note that the second temperature does not necessarily refer to the temperature at a single point.That is, during the heating of the mixture in step S4, the second temperature can vary within a temperature range of a certain degree (for example, in the range of several degrees Celsius to several tens of degrees Celsius). Next, the gas produced by heating the mixture of the first incinerated ash and the ash adhesion inhibitor to a second temperature in step S4 is contacted with the first object made of quartz (S6; contact step). The shape of the first object is not specifically limited. The first object can be a tube with openings at both ends, a test tube, a crucible, a beaker, a cup, a rectangular container, a plate, a cell, or something similar. Steps S4 and S6 may be performed as follows according to the shape or the like of the first object. In one embodiment, the gas generated by heating may be brought into contact with the first object, while the first object and the mixture are heated to a second temperature in a state where the mixture described above is introduced into the first object or in a state where the mixture is placed on the first object (i.e., steps S4 and S6 may be performed simultaneously). Alternatively, in one embodiment, the mixture may be introduced into a container (such as a melting crucible) different from the first object and heated to a second temperature (step S4), and the gas generated therefrom may be directed to the first object and brought into contact with the first object (step S6). Next, the ash adhesion inhibitor is evaluated based on the degree of devitrification present in the first object in step S5 (S8; evaluation step). The inventors of the present invention have found that the degree of devitrification present in quartz when the gas produced by subjecting a mixture of incinerated ash from a fuel and an ash adhesion inhibitor to high temperature treatment is applied or caused to act on the quartz varies depending on the mixing ratio of the fuel and the ash adhesion inhibitor or depending on the type of fuel. The mechanism of ash adhesion in a combustion device discovered by the inventors of the present invention is as follows. That is, volatile components (e.g., alkali metal elements or heavy metal elements) contained in the fuel are volatilized as, for example, hydroxides from the fuel or combustion ash during the combustion of the fuel in the combustion device, and then condensed in the form of, for example, carbonates on the surface of a relatively low temperature device (e.g., a heat transfer tube) in the combustion device to form an initial adhesion layer. Thereafter, the surface of the initial adhesion layer is melted by exposure to a high temperature, and ash adheres to this melted portion. As the thickness of the adhered ash increases, the temperature of the surface layer also increases, the portion of the surface layer melts, and the ash adhesion accelerates. In this way, the ash adhesion layer grows.That is, the volatilization of volatile components (e.g., alkali metals or heavy metals) contained in the fuel in the combustion equipment can be a factor in ash adhesion to the equipment. Here, the relationship between the effect of ash adhesion inhibition by ash adhesion inhibitors and quartz devitrification can be described as follows. The fact that devitrification occurs in quartz by contacting the gas produced in the high-temperature treatment step described above that simulates a phenomenon in a combustion apparatus (S4; the step of treating a mixture of incinerated ash from fuel and ash adhesion inhibitor at high temperature) with quartz indicates that volatile components in the fuel (in the incinerated ash) are volatilized and applied or acted upon the quartz. This is thought to be because quartz devitrification results from changes in the crystal structure and the action of evaporated volatile components (e.g., alkali metal compounds or heavy metal compounds) onto the quartz surface, thus inducing changes in the quartz crystal structure. On the other hand, the fact that the degree of devitrification found in quartz by contacting the gas produced in the same step (high temperature treatment step) with quartz is small indicates that the volatilization of volatile components in the fuel (in the incinerated ash) is inhibited by the ash adhesion inhibitor. Therefore, it is thought that because the degree of devitrification of quartz is small, the volatilization of volatile components during the use of the target fuel is inhibited by the ash adhesion inhibitor, and a higher ash adhesion inhibition effect is obtained. Therefore, according to the method of steps S1 to S8 described above, the effect of inhibition of ash adhesion by an ash adhesion inhibitor upon use of fuel in a combustion apparatus can be precisely evaluated by a simple technique based on the degree of devitrification present in the first substance made of quartz when the gas produced by subjecting the first incinerated ash mixture obtained by heating the fuel and the ash adhesion inhibitor is applied or caused to act on the first substance made of quartz. In step S8, the inhibition effect of ash adhesion by the ash adhesion inhibitor can be evaluated based on the size of the devitrification region of the first object. In this case, for example, because the devitrification region generated on the first object is smaller, the inhibition effect of ash adhesion by the ash adhesion inhibitor can be evaluated higher. The size of the devitrification area can be measured visually using, for example, surveying instruments such as scales or calipers. Alternatively, the size of the devitrification area can be measured using well-known optical measurement techniques, such as absorbance measurement by absorptiometry or scattered light intensity measurement by laser irradiation. In step S8, the inhibition effect of ash adhesion by the ash adhesion inhibitor can be evaluated based on the transmittance of the devitrification region of the first object. In this case, for example, since the transmittance of the devitrification region produced on the first object is larger, the inhibition effect of ash adhesion by the ash adhesion inhibitor can be evaluated higher. The transmittance of a devitrified region can be measured visually, for example. Alternatively, the transmittance of a devitrified region can be measured using well-known optical measurement techniques, such as absorbance measurement by absorptiometry or scattered light intensity measurement by laser irradiation. An evaluation method for an ash adhesion inhibitor according to some embodiments further comprises the step of contacting a gas produced by heating, at a fourth temperature higher than the third temperature, a second incinerated ash obtained by heating a reference fuel different from the fuel described above (the fuel heated in step S2) at a third temperature with a second object made of quartz. In step S8 (the evaluation step), the ash adhesion inhibitor is evaluated based on a comparison between the degree of devitrification present on the first object in step S6 and the degree of devitrification present on the second object. In accordance with the embodiment described above, by comparing the degree of devitrification present on a second object through contact between gases generated by high temperature treatment of incinerated ash from a reference fuel that has been shown to be less likely to cause ash adhesion in the combustion apparatus, and a second object made of quartz with the degree of devitrification present on the first object by the procedure of steps S2 to S6, the suitability of using the fuel used in step S2 and / or the ash adhesion inhibitor used in conjunction with the fuel in the combustion apparatus can be precisely determined by a simple technique. That is, the degree of devitrification found in the second object by high-temperature treatment of the incinerated ash of the reference fuel with the procedure described above serves as an assessment criterion for the suitability of using the evaluation target fuel and / or ash adhesion inhibitor (fuel used in steps S2 to S6 and / or ash adhesion inhibitor) in the combustion equipment. For example, when the degree of devitrification found in the first object is equal to or less than the degree of devitrification found in the second object, it can be judged that the evaluation target fuel and / or ash adhesion inhibitor are suitable for use in the combustion equipment. When the degree of devitrification found in the first object is greater than the degree of devitrification found in the second object, it can be judged that the evaluation target fuel and / or ash adhesion inhibitor are not suitable for use in the combustion equipment. The shape of the second object may be identical to the shape of the first. In this case, it will be easy to compare the degree of devitrification present in the first object with the degree of devitrification present in the second object. Examples Steps S1 through S6 described above were performed using biomass fuel and ash adhesion inhibitor (Examples 1 through 3) in the amounts indicated below. Note that the biomass fuel and ash adhesion inhibitor used in Examples 1 through 3 are identical. Example 1 ... Biomass fuel: A, ash adhesion inhibitor = 0 Example 2 ... Biomass fuel: A, ash adhesion inhibitor = B Example 3 ... Biomass fuel: A, ash adhesion inhibitor = twice the amount of B in Example 2 Specifically, the following procedures are performed for each of Examples 1 to 3. First, the biomass fuel is heated at 600 °C to obtain the first incinerated ash. Next, the first incinerated ash and a predetermined amount of ash adhesion inhibitor are mixed, introduced into a quartz tube, and heated at 1300 °C to 1500 °C (high-temperature treatment step). The gas produced in the quartz tube is contacted with the inner wall surface of the quartz tube (contact step). Note that in Example 1, in the high-temperature treatment step, only the first incinerated ash is introduced into the quartz tube and heated at 1300 °C to 1500 °C without mixing the ash adhesion inhibitor. Figure 3 is a photograph illustrating the results of performing the above procedure for Examples 1 to 3. Figure 3 shows that for each of Examples 1 to 3, devitrification (devitrification regions R1 to R3 appearing white) is present in the originally transparent quartz tube. When the length (length in the direction of the quartz tube length) of the devitrification regions R1 to R3 in Examples 1 to 3 is measured with a scale and compared, when the length of the devitrification region R1 in Example 1 is 1, the length of the devitrification region R2 in Example 2 is 0.77, and the length of the devitrification region R3 in Example 3 is 0.24. That is, among Examples to 3, the degree of devitrification in Example 1 where the ash adhesion inhibitor is not used is the largest, and the degree of devitrification in Example 3 where the amount of ash adhesion inhibitor is used is the smallest. This indicates that the devitrification of the quartz tube is inhibited by the ash adhesion inhibitor (i.e., the volatilization of volatile components during the combustion of biomass fuel is inhibited). Furthermore, the effect of inhibiting devitrification may change depending on the amount of ash adhesion inhibitor.These results indicate that the effect of ash adhesion inhibitors can be evaluated based on the size of the devitrification area. When the transmittance of the devitrification areas R1 to R3 in Examples 1 to 3 was visually compared, the transmittance of the devitrification area R1 in Example 1 and the devitrification area in Example 2 was relatively low, and the transmittance of the devitrification area R3 in Example 3 was relatively high. That is, among Examples 1 to 3, the degree of devitrification in Examples 1 and 2 was relatively large, and the degree of devitrification in Example 3 where the largest amount of ash adhesion inhibitor was used was relatively small. This indicates that the devitrification of the quartz tube was inhibited by the ash adhesion inhibitor (i.e., the volatilization of volatile components during biomass fuel combustion was inhibited). Furthermore, the effect of inhibiting devitrification may change depending on the amount of ash adhesion inhibitor. These results indicate that the effect of ash adhesion inhibitor can be evaluated based on the transmittance of the devitrification area. Figure 4 is a graph showing the reduction in biomass fuel quantity before and after the high temperature treatment step (the step of heating the mixture of first incinerated ash and / or ash adhesion inhibitor in a quartz tube at a temperature of 1300 °C to 1500 °C) for each of Examples 1 to 3. Figure 5 is a table showing the composition of the first incinerated ash (Examples 1 to 3) before performing the high temperature treatment step. According to the graph in Figure 4, the quantity reduction of the first incinerated ash is 43.5% b. in Example 1, 22.6% b. in Example 2, and 11.1% b in Example 3. Therefore, it can be seen that the amount of components volatilized in the high-temperature treatment step is large in the order of Example 1, Example 2, and Example 3. Among the incinerated ash components shown in the table in Figure 5, the total of SO3, Na2O, K2O, carbonic acid, moisture, and other components, which are considered as volatile components, became 47.3% b. This numerical value is the same degree as the reduction in quantity (43.5% b.) of biomass fuel in Example 1 shown in the graph in Figure 4. This indicates that in Example 1, alkali metal compounds (Na and K) were volatilized by carrying out the high-temperature treatment step. In Examples 2 and 3, it is estimated that not all alkali metal compounds (Na and K) were volatilized even after the high-temperature treatment step. These results indicate that there is a relationship between the degree of devitrification of quartz tubes and the effect of inhibiting the volatilization of volatile components by ash adhesion inhibitors (i.e., ash adhesion inhibition effect). Each of the contents described in the above embodiments is summarized as follows, by way of example. (1) An evaluation method for an ash adhesion inhibitor according to at least one embodiment of the present invention is an evaluation method for an ash adhesion inhibitor used in a combustion apparatus (100), the evaluation method comprising: step (S2) to heat the fuel containing volatile components to the first temperature to obtain the first incinerated ash containing volatile components; high temperature treatment step (S4) to heat the mixture of the first incinerated ash and ash adhesion inhibitor to a second temperature higher than the first temperature; a contact step (S6) to contact the gas produced in the high temperature treatment step with the first object made of quartz; and an evaluation step (S8) to evaluate the ash adhesion inhibitor based on the degree of devitrification present on the first object in the contact step. The inventors of the present invention have found that the degree of devitrification present in quartz when the gas produced by subjecting a mixture of incinerated ash from a fuel and an ash adhesion inhibitor to high temperature treatment is applied or caused to act on the quartz varies depending on the mixing ratio of the fuel and the ash adhesion inhibitor or depending on the type of fuel. The relationship between the effect of ash adhesion inhibition by ash adhesion inhibitors and quartz devitrification can be explained as follows. That is, volatile components contained in the fuel volatilize during combustion or the like of the fuel in the combustion equipment and then solidify on the surface of the equipment (e.g., heat transfer tube), which can be a factor in ash adhesion to the equipment. Here, the fact that devitrification occurs on quartz by contacting the gas produced in the high-temperature treatment step that simulates a phenomenon in the combustion equipment (the step of treating the mixture of incinerated ash from the fuel and ash adhesion inhibitor at high temperature) with quartz indicates that the volatile components in the fuel (in the incinerated ash) are volatilized and applied or acted on the quartz.On the other hand, the fact that the degree of devitrification found in quartz by contacting the gas produced at the same step with quartz is small indicates that the volatilization of volatile components in the fuel (in the incinerated ash) is inhibited by the ash adhesion inhibitor. Therefore, it is thought that because the degree of devitrification of quartz is small, the volatilization of volatile components during the use of the target fuel is inhibited by the ash adhesion inhibitor, and a higher ash adhesion inhibition effect is obtained. In accordance with the method (1) described above, the effect of inhibition of ash adhesion by an ash adhesion inhibitor during the use of fuel in a combustion apparatus can be accurately evaluated by a simple technique based on the degree of devitrification present in the first substance made of quartz when the gas produced by subjecting a mixture of incinerated ash from the fuel and the ash adhesion inhibitor to high temperature is applied or caused to act on the first substance made of quartz. (2) In some embodiments, in method (1) described above, the volatile component contains an alkali metal, and the ash adhesion inhibitor contains an aluminosilicate. Alkali metals (alkali metal compounds) contained in relatively large amounts in biomass fuels or the like volatilize during combustion or the like of such fuels and then solidify on the surface of the equipment (e.g., heat transfer tubes), which can be a factor in ash adhesion to the equipment. In this case, according to the method (2) described above, the effect of ash adhesion inhibition by ash adhesion inhibitors containing aluminosilicates when using fuel in combustion equipment can be accurately evaluated by a simple technique based on the degree of devitrification contained in the first substance made of quartz when the gas produced by subjecting a mixture of incinerated ash from the fuel and ash adhesion inhibitors containing aluminosilicates to high-temperature treatment is applied or caused to act on the first substance. (3) In some embodiments, in method (1) or (2) described above, the volatile component contains an alkali metal, and the ash adhesion inhibitor contains kaolinite, halloysite, pyrophyllite, bentonite, or silica. Alkali metals (alkali metal compounds) contained in relatively large amounts in biomass fuels or the like volatilize during combustion or the like of such fuels and then solidify on the surface of the equipment (e.g., heat transfer tubes), which can be a factor in ash adhesion to the equipment. In this case, according to the method (3) described above, the ash adhesion inhibition effect by an ash adhesion inhibitor containing the above-described substance when using the fuel in the combustion equipment can be accurately evaluated by a simple technique based on the degree of devitrification contained in the first substance made of quartz when the gas produced by subjecting the mixture of incinerated ash from the fuel and an ash adhesion inhibitor containing kaolinite, halloysite, bentonite, or silica is applied or caused to act on the first substance. (4) In some embodiments, in the method (1) described above, the volatile component contains heavy metals, and the ash adhesion inhibitor contains a sulfur-containing substance. Heavy metals (heavy metal compounds) that are contained in relatively large amounts in waste fuel or the like volatilize during combustion or the like of said fuel and then solidify on the surface of the equipment (e.g., heat transfer tube), which can be a factor in ash adhesion to the equipment.In this case, according to the method (4) described above, the effect of inhibition of ash adhesion by an ash adhesion inhibitor containing a sulfur-containing substance upon use of fuel in a combustion apparatus can be precisely evaluated by a simple technique based on the degree of devitrification present in the first substance made of quartz when the gas produced by subjecting a mixture of incinerated ash from the fuel and the ash adhesion inhibitor containing a sulfur-containing substance to high temperature treatment is applied or caused to act on the first substance. (5) In some embodiments, in any one of the methods (1) to (4) described above, in the evaluation step, the ash adhesion inhibitor is evaluated based on the size of the devitrification region (R1 to R3) of the first object. According to the method (5) described above, the inhibition effect of ash adhesion by an ash adhesion inhibitor during the use of fuel in a combustion device can be precisely evaluated by a simple technique based on the size of the devitrification area produced on the first object made of quartz. For example, because the devitrification area produced on the first object is smaller, the inhibition effect of ash adhesion by an ash adhesion inhibitor can be evaluated higher. (6) In some embodiments, in any one of the methods (1) to (5) described above, in the evaluation step, the ash adhesion inhibitor is evaluated based on the transmittance of the devitrification region (R1 to R3) of the first object. According to the method (6) described above, the inhibition effect of ash adhesion by an ash adhesion inhibitor during the use of fuel in a combustion device can be accurately evaluated by a simple technique based on the transmittance of the devitrification area generated on the first object made of quartz. For example, because the transmittance of the devitrification area generated on the first object is larger, the inhibition effect of ash adhesion by an ash adhesion inhibitor can be evaluated higher. (7) In some embodiments, in any one of the methods (1) to (6) described above, the fuel contains biomass, and the first temperature is equal to or greater than 500 °C and equal to or less than 650 °C. According to the method (7) described above, biomass fuel generally containing a relatively large amount of alkali metal is heated in a temperature range equal to or greater than 500 °C and equal to or less than 650 °C to obtain incinerated ash, and therefore, the volatilization of alkali metal during heating can be inhibited and incinerated ash retaining alkali metal compounds (volatile components) can be obtained. Therefore, the effect (i.e., the inhibition effect of ash adhesion in the combustion equipment) of inhibiting the volatilization of alkali metal compounds during fuel combustion by an ash adhesion inhibitor can be evaluated by performing the following steps (high temperature treatment, contact, and evaluation steps). (8) In some embodiments, any one of the methods (1) to (7) described above includes the step of contacting the gas produced by heating, at a fourth temperature higher than the third temperature, a second incinerated ash obtained by heating a reference fuel different from the fuel at the third temperature with a second object made of quartz, and in the evaluation step, the adhesion inhibitor of the ash is evaluated based on a comparison between the degree of devitrification present on the first object and the degree of devitrification present on the second object. In accordance with the method (8) described above, by comparing the degree of devitrification present on a second object through contact between the gas generated by high temperature treatment of incinerated ash from a reference fuel that has been shown to be less likely to cause ash adhesion in the combustion apparatus, and a second object made of quartz with the degree of devitrification present on the first object by the procedure (1) described above, the suitability of using the fuel used in the procedure (1) described above and / or the ash adhesion inhibitor used in conjunction with the fuel in the combustion apparatus can be precisely determined by a simple technique. Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and also includes modifications of the embodiments described above as well as suitable combinations of such embodiments. Here, expressions of relative or absolute arrangement such as in a direction, along a direction, parallel, orthogonal, central, concentric, or coaxial should not be interpreted as indicating only arrangement in the strict literal sense, but also as indicating a state in which the arrangement is relatively displaced by a tolerance, or by an angle or distance that can still achieve the same function. For example, expressions indicating a state of equality such as the same, equal, or uniform should not be interpreted as indicating only a state of absolute equality, but also as indicating a state where there is tolerance or differences that can still achieve the same function. In addition, in this specification, expressions such as rectangular or cylindrical shall not be interpreted as indicating only geometrically strict shapes, but also as indicating shapes with irregularities or beveled or similar angles within the range where the same effect can be achieved. Additionally, in this specification, expressions such as comprising, including, or having one component are not intended to exclude other components. List of Reference Marks Kettle Furnace Combustion gas path Fuel gas path Exhaust duct Combustion device, 21A to 21F Burner, 22A to 22F Pulverized fuel pipe wind box Air ducts, 31A to 31F Fuel supply section Forced fan Gas line Air preheater DeNox Equipment Device Desulfurizer Chimney 100 Combustion equipment 101 Furnace walls 102 , 102A to 102C Advanced heating 103 , 103A to 103B Reheater 104 Saver R1 to R3 Devitrification area

Claims

1. An evaluation method for an ash adhesion inhibitor used in a combustion apparatus, the evaluation method comprising: the step of heating a fuel containing a volatile component at a first temperature to obtain a first incinerated ash containing a volatile component; a high-temperature treatment step for heating a mixture of the first incinerated ash and the ash adhesion inhibitor at a second temperature higher than the first temperature; a contact step for contacting the gas produced in the high-temperature treatment step with a first object made of quartz; and an evaluation step for evaluating the ash adhesion inhibitor based on the degree of devitrification present on the first object in the contact step.

2. An evaluation method for an ash adhesion inhibitor according to claim 1, wherein the volatile component contains an alkali metal, and the ash adhesion inhibitor contains an aluminosilicate.

3. An evaluation method for an ash adhesion inhibitor according to claim 1 or 2, wherein the volatile component contains an alkali metal, and the ash adhesion inhibitor contains kaolinite, halloysite, bentonite, or silica.

4. An evaluation method for an ash adhesion inhibitor according to claim 1, wherein the volatile component contains a heavy metal, and the ash adhesion inhibitor contains a sulfur-containing substance.

5. An evaluation method for an ash adhesion inhibitor according to any one of claims 1 to 4, wherein in the evaluation step, the ash adhesion inhibitor is evaluated based on the size of the devitrification area of ​​the first object.

6. An evaluation method for an ash adhesion inhibitor according to any one of claims 1 to 5, wherein in the evaluation step, the ash adhesion inhibitor is evaluated based on the transmittance of the devitrification area of ​​the first object.

7. An evaluation method for an ash adhesion inhibitor according to any one of claims 1 to 6, wherein the fuel contains biomass, and the first temperature is equal to or greater than 500 °C and equal to or less than 650 °C.

8. An evaluation method for an ash adhesion inhibitor according to any one of claims 1 to 7, further comprising: the step of contacting a gas produced by heating, at a fourth temperature higher than the third temperature, a second incinerated ash obtained by heating a reference fuel different from the fuel at the third temperature, with a second object made of quartz, wherein in the evaluation step, the ash adhesion inhibitor is evaluated based on a comparison between the degree of devitrification present on the first object and the degree of devitrification present on the second object.

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