Composition

Abstract

The present invention pertains to a composition for stopping combustion occurring in a solar power generation facility, the composition having a light transmission reduction material and a dispersant that disperses the light transmission reduction material. By dispersing the light transmission reduction material, the composition itself has light-shielding properties and partially or substantially completely blocks the light necessary for power generation in the solar power generation facility. Carbon particles such as carbon black can be used as the light transmission reduction material. If carbon particles are employed as the light transmission reduction material, the concentration of the carbon particles is preferably 0.2 mg / L or more. Furthermore, the dispersant is preferably a surfactant.

Description

Composition

[0001] The present invention relates to a composition for suppressing the combustion of solar power generation equipment.

[0002] In recent years, both at home and abroad, the use of solar power generation equipment having solar panels has been expanding, and large-scale solar power generation facilities integrating solar panels and buildings equipped with solar panels have been increasing. Fire-fighting activities against fires in solar power generation equipment involve the risk of electric shock due to the power generation of the solar power generation equipment. This is because when the solar panels and their surroundings are wetted by water discharge for fire extinguishing while the power generation module is generating electricity, it causes electric leakage. In equipment where a plurality of solar panels are connected by cables, even if the solar panels are disconnected from the system by cutting the cables, the power generation of the disconnected solar panels themselves does not stop, and electric leakage occurs from the cable cutting point.

[0003] Therefore, when extinguishing a fire in solar power generation equipment, it is important to stop the power generation of the power generation module, but an effective method has not been established yet. In fact, fires in solar power generation equipment are difficult to extinguish, and there are many cases where fire-fighting activities take several days, and currently, it has become a major social problem.

[0004] Regarding the stoppage of power generation of the power generation module, Non-Patent Document 1 describes a method of stopping the power generation of the power generation module by shading the solar panel with a light-shielding body such as a salvage cover or a waterproof sheet. However, the degree of shading of the waterproof sheet varies greatly. In this regard, Non-Patent Document 2 describes that generally, the power generation of the power generation module can be reduced to almost zero by a light-shielding body composed of a combination of a thick and densely woven fabric and a dark-colored plastic film.

[0005] Ramali, MR, Ong, NAFMN, Said, MSM, Yusoff, HM, Baharudin, MR, Tharima, AF, Akashah, FW, and Tohir, MZM (2023) A review on safety practices for firefighters during photovoltaic (PV) fire. Fire Technol 59: 247-270.Backstrom R, Dini D (2012) Firefighter safety and photovoltaic installations research project, 8472SPIE, Bellingham

[0006] However, adopting this method is not practical, and is especially impractical for sites with solar panels installed on rooftops or large-scale solar power generation facilities. This is for the following reasons: First, it is difficult to procure shading materials of a size appropriate to the size and number of solar panels at a fire site. Second, it is difficult to erect large shading materials on rooftops. Furthermore, it is difficult to maintain the state in which the solar panels are covered by shading materials in environments where wind is present. Moreover, such shading sheets do not have the effect of preventing the spread of fire from the source of ignition, and are flammable, so fire protection cannot be expected.

[0007] Here, we will summarize the firefighting strategy for a fire in a solar power generation facility. As shown in Figure 7, let's assume that a fire breaks out on solar panel 100, one of several solar panels 100, 101, 102, and 103. In this case, direct firefighting activities are required for solar panel 100, two measures are required for solar panel 101 adjacent to solar panel 100: fire prevention and power generation interruption, and power generation interruption is required for the surrounding solar panels 102 and 103.

[0008] When attempting to stop power generation by solar panel 101 by shading, shading of solar panel 101 must be carried out in conjunction with measures to prevent the spread of fire. Furthermore, it should be noted that the shading measures themselves may be hindered by the heat of the fire from solar panel 100. These points also apply to a single solar panel, where the burning portion and the area surrounding it correspond to solar panel 100 and solar panel 101 in the example described above.

[0009] Furthermore, even when a fire is occurring near the solar panels but the solar panels themselves are not catching fire, the measures described above for solar panels 101, 102, and 103 are still effective. This is because these measures can prevent the solar panels 101, 102, and 103 from burning and ensure safe firefighting operations.

[0010] The present invention has been made in view of these circumstances, and aims to provide a composition that suppresses combustion of a solar power generation facility from a fire occurring in or near the facility.

[0011] A composition according to the present invention that serves the above purpose is a composition that suppresses combustion in a solar power generation facility, comprising a light-transmitting substance that reduces the amount of light transmitted of wavelengths used for solar power generation by the solar power generation facility, and a dispersant that disperses the light-transmitting substance.

[0012] The composition according to the present invention comprises a light-transmitting agent that reduces the amount of light transmitted at wavelengths used for solar power generation by a solar power generation facility, and a dispersant that disperses the light-transmitting agent. Therefore, the composition itself has the function of stopping or suppressing the power generation of solar panels and can suppress the combustion of the solar power generation facility from a fire that occurs in or near the solar power generation facility.

[0013] This is an explanatory diagram showing the appearance of the sample over time. This is an explanatory diagram showing the experimental results of the light-shielding properties of the sample. This is an explanatory diagram showing the experimental results of the light-shielding properties of the sample. (A) and (B) are explanatory diagrams showing the experimental results of the light-transmitting properties of the sample, respectively. These are images taken during an experiment on the persistence of the foamed state of the sample. (A) and (B) are images taken during an experiment on the movement of a sample on a solar panel over time, respectively. This is an explanatory diagram of a fire in a solar power generation facility.

[0014] Next, embodiments of the present invention will be described to facilitate understanding of the present invention. One embodiment of the present invention is a composition that suppresses combustion in a solar power generation facility and comprises a light-transmitting substance that reduces the amount of light transmitted and a dispersant that disperses the light-transmitting substance.

[0015] The composition may consist only of a light-reducing agent and a dispersant, or it may contain other substances such as a diluent (e.g., water) in addition to the light-reducing agent and dispersant. The composition may be a liquid, a solid, or a mixture of liquid and solid. An example of a solid composition is a powdered composition. The composition has the functions of a fire extinguishing agent to put out fires, a fire spread inhibitor to prevent the spread of fire, and a combustion inhibitor to suppress combustion. In addition to these, the composition also has the function of a light-shielding agent to reduce the amount of light transmitted through wavelengths of light used for solar power generation by photovoltaic power generation equipment. The composition suppresses or blocks the reach of light to the solar panels of photovoltaic power generation equipment by its light-shielding properties.

[0016] Light-reducing materials have light-shielding properties and impart light-shielding performance to the composition. In this embodiment, the light-reducing material used is one that reduces the amount of light transmitted by blocking some or all of the light in the wavelength range of 380 nm to 1100 nm. However, it is not limited to this range. The light-reducing material used is one that can block some or all of the light of wavelengths used for solar power generation in the target solar power generation facility. Here, reducing the amount of light transmitted by the light-reducing material is a concept that encompasses both completely blocking the transmission of light through the light-reducing material and reducing the amount of light transmitted through the light-reducing material.

[0017] In this embodiment, the light-reducing substance is a pigment (including pigments in a broad sense, natural pigments, pigments, and dyes) that has a color visible to the human eye, and its color is, for example, black (however, it is not limited to black). The light-reducing substance can be composed of one type of substance or multiple types of substances, and pigments and dyes can be used as the light-reducing substance. Examples of pigments include carbon particles such as carbon black and soot, and red carmine. Examples of dyes include the black dye nigrosine and the blue dye methylene blue.

[0018] Compositions containing light-transmitting substances have higher light-shielding properties than compositions without such substances, even if the amount is trace, and can stop or suppress power generation of power generation modules. However, in order for a composition to stably have a certain level of light-shielding properties, if the light-transmitting substance is carbon particles, the concentration of carbon particles in the composition is preferably 0.2 mg / L or more, preferably 2 mg / L or more, more preferably 10 mg / L or more, and more preferably 20 mg / L or more.

[0019] On the other hand, since carbon particles conduct electricity, if the concentration of carbon particles is excessively high, under certain conditions, leakage current from solar panels during power generation may cause electric shock to the composition. From this viewpoint, a carbon particle concentration of 1.0 g / L or less is preferred, 0.5 g / L is more preferred, and 0.2 g / L or less is even more preferred. Furthermore, the light-reducing material may be a substance that does not have a color visible to the human eye at room temperature, or has a light color, and acquires or darkens in color at high temperatures (e.g., 60°C or higher), such as the white of a bird's egg.

[0020] There are no particular limitations on the dispersant; for example, foaming surfactants and polymer-type dispersants can be used. Hereinafter, when simply referred to as "surfactant," it means a foaming surfactant. When the dispersant is a surfactant, the composition can be stably maintained in a state of adhesion to solar panels installed at an angle to the horizontal plane.

[0021] Experiments have verified that compositions using surfactants as dispersants exhibit improved light-shielding performance due to their foaming state. Therefore, compositions using surfactants as dispersants can compensate for the impact of reduced light-shielding properties caused by lowering the concentration of light-reducing substances. Existing foaming fire extinguishing agents can also be used as dispersants. Furthermore, from the viewpoint of suppressing the liquefaction of the foamed layer over time, it is preferable for the composition to contain a thickening agent (such as xanthan gum).

[0022] If the composition contains a thickening agent, a composition containing the thickening agent beforehand can be used. Furthermore, depending on the type and concentration of the thickening agent, it is preferable to mix the thickening agent with other substances in the composition at the point of use. For example, the other substances and the thickening agent can be mixed at the point of use by spraying them from separate nozzles. This prevents, for example, the composition containing the thickening agent from gelling before use.

[0023] Furthermore, the light-reducing agent does not need to be mixed with the dispersant beforehand. For example, at the site of use of the composition, the dispersant may first be sprayed onto the object, and then the light-reducing agent may be sprayed onto the dispersant that has been sprayed onto the object.

[0024] The surfactants that can be used as dispersants may be synthetic surfactants or surfactants with soap as the main component, but from the viewpoint of reducing the burden on the environment, surfactants with soap as the main component are preferred. Liquefied CO2 as a dispersant ２ It is also possible to use liquefied CO2 as a dispersant. ２ In that case, liquefied CO2 with light-reducing substances dispersed in it. ２ The composition can be prepared by solidifying it into a powder. Experimental example

[0025] Next, we will describe the experiments conducted to confirm the effects of the present invention.

[0026] <Experiment 1> Seven compositions (hereinafter simply referred to as "samples") were prepared in 10 mL portions in test tubes, and their state after preparation was observed. The upper table in Figure 1 shows the components and concentrations of each sample. "CBB" in the table stands for carbon black, and the concentration g / L listed for carbon black represents the concentration of carbon black relative to the sample.

[0027] In addition, in the table, "EtOH" refers to ethanol, "MF" refers to Miracle Foam®, a composition containing a surfactant mainly composed of soap, "PC" refers to Phoscheck®, a commercially available composition containing a hydrocarbon surfactant, and "%" refers to mass volume percentage concentration (w / v%). The same applies hereafter.

[0028] Sample 1 (the sample marked with a 1 in a circle in Figure 1), which contained a primary and secondary dispersant, was prepared by dispersing carbon black with the primary dispersant and then stirring it with the secondary dispersant and diluent water. Samples 2 to 7 (each marked with a number 2 to 7 in a circle in Figure 1), which did not use a secondary dispersant, were prepared by dispersing carbon black with the primary dispersant and then stirring it with diluent water.

[0029] The upper, middle, and lower photographs in Figure 1, showing samples 1 to 7 arranged side by side, are as follows: the upper photograph was taken immediately after preparation (immediately after stirring), the middle photograph was taken 30 minutes after preparation, and the lower photograph was taken 4 days after preparation.

[0030] The experimental results showed that sample 1 produced less foaming immediately after preparation compared to samples 2-7, and less carbon black-containing foam adhered to the inside of the test tube (for example, at the position of the triangular mark in the photograph in Figure 1). Furthermore, compared to the other samples, sample 1 showed a more pronounced separation between dense and sparse layers of carbon black after standing, and as seen in the photograph taken 4 days after preparation, there was a large color difference between the lower black layer where carbon black had precipitated in the solution and the upper, more transparent layer (at the position of the arrow in the photograph in Figure 1).

[0031] Therefore, when using Sample 1 for fire extinguishing in a solar power generation facility, from the viewpoint of efficiently blocking light, it is preferable to disperse the carbon black throughout Sample 1 by shaking the container containing Sample 1 immediately before use.

[0032] In contrast, samples 2-7 showed good dispersion of carbon black, and it was confirmed that black foam formed above the triangular mark in the photograph in Figure 1 (see photograph taken immediately after preparation). Even 30 minutes and 4 days after preparation, as can be seen in the respective photographs, the carbon black remained dispersed in the solution (not in the foam, but in the solution itself). That is, unlike sample 1, the carbon black did not precipitate in the solution.

[0033] In the photograph in Figure 1, the arrow points to just below the 10 mL mark in the test tube. In the photographs taken 30 minutes and 4 days after preparation, the liquid level of the solutions in samples 2-7 was at the height just above the arrow. After 4 days from preparation, bubbles were virtually absent or minimal in all of samples 1-7. Of samples 1-7, sample 6 exhibited the best foaming performance and had the most black bubbles adhering to the inside of the test tube 30 minutes after preparation.

[0034] <Second Experiment> For each of samples 1 and 6 described above, four days after preparation, the supernatant of the solution was collected to form a 4 mm thick layer. Then, white light was shone onto this supernatant layer from a light source, and the light intensity was measured on the opposite side of the light source, using the supernatant layer as a reference. The measurement results are shown in Figure 2. From the measurement results in Figure 2, the supernatant of sample 1 uniformly attenuated light of all wavelengths in the visible light range, and the light transmittance was 28.5%. The supernatant of sample 6 had a light transmittance of 0.06%, and the light shielding rate was close to 100%.

[0035] <Third Experiment> For Sample 6, several samples with varying carbon black concentrations were prepared. White light was shone onto each sample from a light source, and the illuminance was measured using a solar cell-type illuminometer on the opposite side of the light source, with the sample as the reference. For each sample, the illuminance was measured both in a static state without foaming and in a state where foaming was induced by shaking (bubble thickness, 20 mm) in a transparent container. The carbon black concentration of the sample with the lowest carbon black concentration was 2 mg / L.

[0036] The measurement results are shown in Figure 3. In Figure 3, the area labeled "Static Area" and indicated by a dashed line and circle represents the measurement results for samples in a non-foaming state, while the area labeled "Shaking Area" and indicated by a solid line and triangle represents the measurement results for samples in a foamed state. From the measurement results shown in Figure 3, it was confirmed that the foamed state had higher light-shielding properties compared to the non-foaming state. This is thought to be because light scattering by the bubbles in the foamed sample contributed to the light-shielding properties.

[0037] Generally, when using a fire pump truck equipped with firefighting equipment specialized for foam extinguishing agents, such as a CAFS (Compressed Air Foam System), it is possible to build up layers of foam with a thickness of 100 mm or more. It has also been reported that a 100 mm thick foam layer can reduce light shielding (Non-Patent Literature 1). Estimating the light shielding rate of a 100 mm thick foam from the light shielding rate of a 20 mm thick foam shown in this experiment (Figure 3) (e.g., 18% at a carbon black concentration of 6 mg / L, and 80% at 20 mg / L), it can be estimated that when compositions containing 6 mg / L and 20 mg / L of carbon black are foamed, the light shielding rates of a 100 mm thick foam are 62.9% and 99.9%, respectively.

[0038] <Fourth Experiment> Using carbon black, surfactant, and diluted water as raw materials, five samples with different types of surfactants were prepared, and illuminance measurements were performed on each sample in the same manner as in the third experiment. All samples had a carbon black concentration of 20 mg / L and a surfactant concentration of 1% (w / v). The results of the surfactant and illuminance measurements for each sample are shown in Table 1 below.

[0039]

[0040] <Fifth Experiment> 20 mL of the sample was placed in a transparent 50 mL container, and the illuminance of the light transmitted through the sample was measured by irradiating the sample with light through the container under static conditions where the sample was not foamed and under foaming conditions where the sample was foamed. The thickness of the sample in the light irradiation direction was 7 mm thick under static conditions and 20 mm thick (all foamed layers) under foaming conditions.

[0041] First, various samples were prepared by mixing various dyes with 1% (w / v) linear alkylbenzene sulfonate (LAS) diluted with water for concentration adjustment, and the same measurement was performed. The illuminance of the light irradiated to the sample was 4400 lux. Hereinafter, unless otherwise specified, the concentration adjustment was performed by dilution with water. The measurement results are shown in Table 2 below.

[0042]

[0043] Next, the same measurement was performed on samples prepared by mixing ink with 2% (w / v) of Miracle Foam (registered trademark). A plurality of samples with different ink concentrations were prepared. Among the plurality of prepared samples, 5 samples were those to which xanthan gum was additionally added, and 1 sample was those to which egg white was additionally added. The illuminance of the light irradiated to the sample was 4550 lux. The measurement results are shown in Table 3 below.

[0044]

[0045] In the samples shown in Table 3, the sample described as "egg white" had an egg white concentration of 2% (v / v) with respect to the sample. The sample described as "xanthan gum" had a xanthan gum concentration of 1% (w / v) with respect to the sample. The sample described as "no addition" had neither xanthan gum nor egg white added.

[0046] Next, the same measurement was performed on samples prepared by mixing various dyes with 2% (w / v) of Fostech Check (registered trademark) with concentration adjustment. The illuminance of the light irradiated to the sample was 4550 lux. The measurement results are shown in Table 4 below.

[0047]

[0048] Next, the same measurement was performed on samples containing 2% (w / v) Phoscheck® and 1% (w / v) linear alkylbenzene sulfonate, each mixed with nigrosine, a black dye. Each sample had a different concentration of nigrosine. The measurement results for the sample containing Phoscheck® are shown in Figure 4(A), and the measurement results for the sample containing linear alkylbenzene sulfonate are shown in Figure 4(B). Measurements were performed with the samples in both a static and foaming state.

[0049] <Experiment 6> First, all samples from the samples shown in Table 3 of Experiment 5, except for the two samples mixed with egg white, were allowed to stand for 30 minutes after being allowed to foam, and then the samples were imaged. The images of each sample are shown in Figure 5. In all samples without xanthan gum, a liquid layer separated from the foamed layer was visible. In contrast, in all samples with xanthan gum added, a liquid layer separated from the foamed layer was not visible.

[0050] <Experiment 7> A sample was prepared by adding India ink (0.1% (v / v) of the total) and xanthan gum (2% (w / v) of the total) to 2% (w / v) of Miracle Foam (registered trademark) and mixing. The sample was foamed and sprayed onto a solar panel measuring 290 mm in length, 340 mm in width, and 25 mm in thickness. The extent to which the sample moved on the solar panel over time was then visually observed when the solar panel was positioned vertically and when it was positioned at an angle of 37.5 degrees to the horizontal. Note that 37.5 degrees is the average roof inclination angle in Japan.

[0051] Figures 6(A) and 6(B) show images taken after the sample was sprayed onto the solar panel. Figure 6(A) is an image from an experiment where the solar panel was positioned vertically, and Figure 6(B) is an image from an experiment where the solar panel was positioned at a 37.5-degree angle. The results showed that the sample moved approximately 1 cm downwards in one minute on the vertically positioned solar panel, while on the 37.5-degree positioned solar panel, the sample remained in place for five minutes of observation.

[0052] <Experiment 8> A sample was prepared by adding India ink (0.5% (v / v) of the total) and xanthan gum (0.2% (w / v) of the total) to 3% (w / v) Miracle Foam (registered trademark) and mixing. The sample was foamed and sprayed onto the solar panel used in Experiment 7, which was placed outdoors, and the current generated by the solar panel was measured before and after spraying. The experiment was conducted on a sunny day, and the solar panel was positioned at an angle of 37 degrees to the horizontal. As a result of the experiment, the current value, which was 4.83A before spraying the sample, became 0.00A after spraying the sample.

[0053] Although embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and any changes to conditions that do not depart from the gist of the invention are all within the scope of application.

[0054] The composition of the present invention not only extinguishes fires on solar panels, but also prevents the spread of fire to unaffected solar panels and suppresses power generation by solar panels. Therefore, it can be used particularly in firefighting activities against fires occurring in or near photovoltaic power generation facilities. Furthermore, the composition of the present invention containing a surfactant can form a light-shielding foam layer (firebreak) on solar panels. This foam layer blocks the light necessary for power generation by the photovoltaic power generation facility, enabling the cessation or suppression of power generation, thereby significantly reducing the risk of electric shock during firefighting activities. Moreover, since the foam layer can simultaneously prevent combustion from flames and heat, prevent the spread of fire to adjacent panels, and extinguish the fire, it brings high safety and practicality to fires at photovoltaic power generation facilities.

Claims

1. A composition for suppressing combustion in a solar power generation facility, characterized by comprising a light-transmitting substance that reduces the amount of light transmitted at wavelengths used for solar power generation by the solar power generation facility, and a dispersant that disperses the light-transmitting substance.

2. The composition according to claim 1, characterized in that the light-transmitting substance is a pigment.

3. The composition according to claim 2, characterized in that the pigment is carbon particles.

4. The composition according to claim 3, characterized in that the carbon particles are carbon black.

5. The composition according to claim 3, characterized in that the concentration of the carbon particles is 0.2 mg / L or more.

6. The composition according to claim 1, characterized in that the light-reducing substance is a dye.

7. The composition according to any one of claims 1 to 6, characterized in that the dispersant is a surfactant.

8. The composition according to any one of claims 1 to 6, characterized by containing a thickening agent.

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