Glass plate level gauge and liquid level measurement method

Abstract

The present invention discloses a glass plate liquid level gauge and a liquid level measurement method. The glass plate liquid level gauge is provided with a front glass plate (1), a rear glass plate (2), a front pressure cover (7), a rear pressure cover (10), a front clamping frame (6), and a rear clamping frame (11). The front pressure cover is provided with a guide hole (12), and the rear pressure cover is provided with an observation hole (3). The front glass plate, the rear glass plate, the front clamping frame, and the rear clamping frame enclose a measuring cavity (5), and the shape of the measuring cavity on the horizontal section is a trapezoid. The intersection lines of the front glass plate emitting surface (15) and the rear glass plate incident surface (16) with the horizontal section are the two waists of the trapezoid, and the intersection lines of the front clamping frame inner surface (8) and the rear clamping frame inner surface (9) with the horizontal section are the two bottom sides of the trapezoid. The present invention discloses a method for liquid level measurement using the above-mentioned glass plate liquid level gauge. The present invention can be used in multiple industries such as petrochemical industry, metallurgy, electricity, food, and medicine to measure the liquid level of transparent or opaque liquids.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid level measurement and relates to a glass plate liquid level gauge and a liquid level measurement method. Background Art

[0002] Glass plate level gauges are used to display liquid levels on equipment in the plant areas of petrochemical refineries. Translucent glass plate level gauges are the most commonly used type. When the measured medium is a transparent liquid and light passes through the liquid column, the light is reflected, refracted, or absorbed, and the intensity of the light passing through the liquid column is weaker than the light passing through the gas above the liquid column. Operators rely on the difference in light intensity between the liquid column and the gas to determine the liquid level. At a slightly greater distance, or on cloudy days or at night when light is dim, the difference in light intensity is minimal, making it more difficult to determine the liquid level. Over time, the inner surface of a glass plate level gauge becomes dirty, weakening the intensity of light passing through it and making it difficult to determine the liquid level. Operators sometimes even need to close the root valve in front of the glass plate level gauge to cause the liquid level to fluctuate noticeably before they can clearly see the liquid level.

[0003] Improving the visual sensitivity of glass plate level gauges is one solution. A common approach is to use red-green color difference to distinguish liquid levels. This approach leverages the principle of total internal reflection and the different refractive indices of the liquid column and the gas medium above it relative to the glass, causing the liquid column and gas to respectively reflect the red and green colors of the glass filter in the background. However, this method only works against bright backgrounds. Against dim or weak backgrounds, the red and green colors are less noticeable, and the light absorption by the filter further reduces light intensity. Observation is also less effective on cloudy days or at night.

[0004] Some glass plate level gauges, particularly boiler water level gauges, use a dedicated external light source, forcing increased background light intensity. These gauges, independent of natural light and factory lighting, are bulky. Explosion-proof lamps and housings must be installed behind the glass, leading to high costs. The need for 220V AC power also requires explosion-proof design considerations, and cabling is also a significant construction effort. Explosion-proof lamps also have a limited lifespan, and running them 24 / 7 increases the risk of failure and requires frequent repairs. Explosion-proof housings also present safety risks. Summary of the Invention

[0005] The object of the present invention is to provide a glass plate liquid level gauge and a liquid level measurement method, so as to solve the problems of the existing glass plate liquid level gauges, such as difficulty in seeing the liquid level clearly and the need for a dedicated external light source.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is: a glass plate liquid level gauge, provided with a front glass plate, a rear glass plate, a front pressure cover, a rear pressure cover, a front clamping frame, and a rear clamping frame, the front pressure cover is provided with a guide hole, the rear pressure cover is provided with an observation hole, the front glass plate, the rear glass plate, the front clamping frame and the rear clamping frame surround a measuring cavity, the surface of the front glass plate adjacent to the measuring cavity is the front glass plate exit surface, the surface of the rear glass plate adjacent to the measuring cavity is the rear glass plate incident surface, the surface of the front clamping frame adjacent to the measuring cavity is the inner surface of the front clamping frame, and the rear clamping frame is adjacent to the measuring cavity. The adjacent surface is the inner surface of the rear clamping frame, the inner surface of the front clamping frame, the inner surface of the rear clamping frame, the two side surfaces of the guide hole and the two side surfaces of the observation hole are parallel to each other, and the characteristic is that: the shape of the measuring cavity on the horizontal section is a trapezoid, the intersection of the front glass plate exit surface and the rear glass plate incident surface with the horizontal section is the two waists of the trapezoid, the intersection of the front clamping frame inner surface and the rear clamping frame inner surface with the horizontal section is the two bottom sides of the trapezoid, and the length of the intersection of the rear clamping frame inner surface with the horizontal section is greater than the length of the intersection of the front clamping frame inner surface with the horizontal section.

[0007] The first embodiment of the method for using the above-mentioned glass plate liquid level gauge to measure the liquid level is as follows: the light outside the glass plate liquid level gauge is emitted to the incident surface of the front glass plate through the guide hole, then enters the front glass plate and passes through the front glass plate, and then is emitted from the emission surface of the front glass plate and enters the measuring cavity. The lower part of the measuring cavity is a liquid column and the upper part is gas. The gas is a transparent gas and the liquid in the liquid column is a transparent liquid. When the light enters the gas, it forms a first light beam, and when it enters the liquid column, it forms a second light beam. The first light beam passes through the gas above the liquid column, and the second light beam passes through the liquid column. Then, the two light beams are connected. The light rays enter the rear glass plate from the incident surface of the rear glass plate and pass through the rear glass plate, and then emerge from different positions on the exit surface of the rear glass plate. Alternatively, the second light ray undergoes total reflection at the position where it intersects with the exit surface of the rear glass plate and does not emerge from the rear glass plate. Finally, the first light ray emerges through the observation hole. At the exit of the observation hole, the human eye, facing the direction of the first light ray, can see the vertical light column formed by the first light ray and the dark background below the vertical light column, but cannot see the second light ray. The bottom of the vertical light column or the top of the dark background represents the liquid level of the liquid column.

[0008] A second embodiment of the method for measuring liquid level using the above-mentioned glass plate liquid level gauge is as follows: light from outside the glass plate liquid level gauge is incident on the front glass plate incident surface through the guide hole, then enters and passes through the front glass plate, and then is emitted from the front glass plate exit surface and enters the measuring cavity. The lower part of the measuring cavity is a liquid column and the upper part is gas. The gas is transparent gas and the liquid in the liquid column is opaque liquid. When the light enters the gas, a first light beam is formed. When it enters the liquid column, a second light beam is formed. The second light beam is absorbed by the liquid in the liquid column and cannot pass through the liquid column. The first light beam passes through the gas above the liquid column, then enters and passes through the rear glass plate from the rear glass plate incident surface, and then is emitted from the rear glass plate exit surface. Finally, the first light beam is emitted through the observation hole. At the exit of the observation hole, the human eye facing the direction of the first light beam can see the vertical light beam formed by the first light beam and the dark background below the vertical light beam. The bottom of the vertical light beam or the top of the dark background represents the liquid level of the liquid column.

[0009] The present invention offers the following beneficial effects: 1. The first light beam, as seen by the human eye, is not absorbed or refracted by the liquid, resulting in a bright vertical beam of light. This beam is clearly distinguishable from the dark background below. Therefore, the liquid level within the measuring chamber can be easily measured, and thus the liquid level within the process equipment. 2. The present invention uses natural light and factory lighting as the external light source for the glass plate level gauge, eliminating the need for a dedicated, external explosion-proof light source, resulting in safety and energy conservation. 3. The glass plate level gauge of the present invention has a relatively simple structure and is easy to manufacture. The desired effects and functions are achieved through optical path calculation. 4. The present invention uses natural light and factory lighting without filters or any light attenuation, preserving the original light intensity to the maximum extent possible. 5. The present invention does not require high external light intensity. The higher the intensity, the clearer the resolution. Even when the external light intensity is low, the liquid level is still easily discerned due to the significant difference in light intensity between the vertical beam of light formed by the first light beam and the dark background below. 6. The glass plate level gauge of the present invention can be designed with a symmetrical structure, enabling bidirectional observation. 7. The glass plate level gauge of the present invention does not require stringent manufacturing requirements. 8. Based on the measurement principle and calculation method of the present invention, the glass plate level gauge of the present invention can be used regardless of whether the liquid is a single component or a mixture, whether the liquid's refractive index can be accurately defined, or whether the liquid is transparent or opaque, thus having a wide range of applications.

[0010] The present invention can be used in various industries such as petrochemical industry, metallurgy, electric power, food and medicine to measure the liquid level of transparent or opaque liquids.

[0011] The present invention will be further described in detail below with reference to the accompanying drawings, specific implementation methods and examples, which do not limit the scope of protection claimed in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1It is a partial cross-sectional view of the glass plate liquid level gauge of the present invention passing through the measuring cavity in the vertical direction.

[0013] Figure 2 yes Figure 1 T-T section view in.

[0014] Figure 3 It is a partial schematic diagram of the vertical light column formed by the first light beam seen by the human eye and the dark background below it.

[0015] Figure 4 This is an optical principle diagram of using the glass plate liquid level meter of the present invention to measure the liquid level and perform the first path light translation calculation ( Figure 1 (Partially enlarged T-T section view in the figure).

[0016] Figures 1 to 4 In the figure, the same reference numerals represent the same technical features. Reference numerals indicate: 1—front glass plate; 2—rear glass plate; 3—observation hole; 4—bolt and nut; 5—measuring cavity; 6—front clamping frame; 7—front pressure cover; 8—inner surface of the front clamping frame; 9—inner surface of the rear clamping frame; 10—rear pressure cover; 11—rear clamping frame; 12—viewing hole; 13—front glass plate incident surface; 14—sealing gasket; 15—front glass plate exit surface; 16—rear glass plate incident surface; 17—rear glass plate exit surface; 18—liquid column in measuring cavity 5; 19—first light ray; 20—second light ray; 21—normal line; 22—vertical light column formed by first light ray 19; 23—dark background below vertical light column 22 formed by first light ray 19; 24—bottom of vertical light column 22 or top of dark background 23; 25—symmetry plane of the glass plate level gauge.

[0017] A—the incident angle of the external light on the front glass plate incident surface 13 of the glass plate level gauge; B—the refraction angle of the external light on the front glass plate incident surface 13; C—the angle between the front glass plate exit surface 15 and the rear glass plate incident surface 16; D—the exit angle of the second light ray 20 on the liquid column 18 in the measuring chamber 5 from the front glass plate exit surface 15; E—the incident angle of the second light ray 20 on the liquid column 18 in the measuring chamber 5 from the liquid column 18 in the measuring chamber 5; F—the refraction angle of the second light ray 20 on the rear glass plate incident surface 16 from the rear glass plate incident surface 16; G—the difference between the exit angle H of the second light ray 20 on the rear glass plate exit surface 17 and the exit angle of the first light ray 19 on the rear glass plate exit surface 17; H—the exit angle of the second light ray 20 The output angle from the rear glass plate output surface 17; K—the output angle of the first light ray 19 from the front glass plate output surface 15; L—the intersection of the normal of the front glass plate incident surface 13 at point O and the front glass plate output surface 15; M—the intersection of the extension line of PO and the front glass plate output surface 15; N—the point where the external light ray PO enters and passes through the front glass plate 1 and then exits from the front glass plate output surface 15; O—the intersection of the external light ray PO and the front glass plate incident surface 13; P—an optional external light calculation position; R—the observation position of the vertical light column 22 formed by the first light ray 19 at the exit of the observation hole 3; u—the width of the guide hole; v—the width of the observation hole; w—the translation distance of the first light ray 19 in the gas in the measurement cavity 5 relative to the external light ray PO. DETAILED DESCRIPTION

[0018] See also Figure 1 and Figure 2 The glass plate level gauge of the present invention is provided with a front glass plate 1, a rear glass plate 2, a front gland 7, a rear gland 10 and a body, and the body is provided with a front clamping frame 6 and a rear clamping frame 11. The front glass plate 1, the rear glass plate 2, the front gland 7, the rear gland 10, the front clamping frame 6 and the rear clamping frame 11 are all arranged vertically. The front gland 7 and the rear gland 10 are connected by bolts and nuts 4. One vertical side sealing portion of the front glass plate 1 is clamped between the front gland 7 and the front clamping frame 6, and the other vertical side sealing portion of the front glass plate 1 is clamped between the front gland 7 and the rear clamping frame 11; one vertical side sealing portion of the rear glass plate 2 is clamped between the rear gland 10 and the front clamping frame 6, and the other vertical side sealing portion of the rear glass plate 2 is clamped between the rear gland 10 and the rear clamping frame 11; a sealing gasket 14 is provided at each clamping position.

[0019] A guide hole 12 is provided on the front pressure cover 7, and an observation hole 3 is provided on the rear pressure cover 10. The guide hole 12 is opposite to the incident surface 13 of the front glass plate, and the observation hole 3 is opposite to the exit surface 17 of the rear glass plate. Both the guide hole 12 and the observation hole 3 are vertical, long, strip-shaped holes, and multiple holes are provided. The guide holes 12 are aligned in a row in the vertical direction, and the observation holes 3 are aligned in a row in the vertical direction. Each guide hole 12 and observation hole 3 has two side surfaces, a top surface, and a bottom surface; the side surfaces are arranged vertically, and the top and bottom surfaces are arranged horizontally. The two side surfaces of the guide hole 12 are parallel to each other, and the two side surfaces of the observation hole 3 are parallel to each other.

[0020] The front glass plate 1, rear glass plate 2, front clamping frame 6, and rear clamping frame 11 enclose the measurement cavity 5. The surface of the front glass plate 1 adjacent to the measurement cavity 5 is the front glass plate exit surface 15, the surface of the rear glass plate 2 adjacent to the measurement cavity 5 is the rear glass plate incident surface 16, the surface of the front clamping frame 6 adjacent to the measurement cavity 5 is the front clamping frame inner surface 8, and the surface of the rear clamping frame 11 adjacent to the measurement cavity 5 is the rear clamping frame inner surface 9. The front glass plate incident surface 13 is parallel to the front glass plate exit surface 15, and the rear glass plate incident surface 16 is parallel to the rear glass plate exit surface 17. The front clamping frame inner surface 8, the rear clamping frame inner surface 9, the two side surfaces of the guide hole 12, and the two side surfaces of the observation hole 3 are parallel to each other.

[0021] Measuring chamber 5 is sealed, with its top and bottom connected to the process equipment (not shown) where the liquid level needs to be measured via pipes. Liquid in the process equipment flows through the pipes into the bottom of measuring chamber 5 and rises until the liquid level in measuring chamber 5 equals the level in the process equipment.

[0022] In the present invention, the measurement cavity 5 has a trapezoidal shape in a horizontal cross-section. The intersections of the front glass plate exit surface 15 and the rear glass plate entrance surface 16 with the horizontal cross-section form the two legs of the trapezoid, while the intersections of the front clamping frame inner surface 8 and the rear clamping frame inner surface 9 with the horizontal cross-section form the two bases of the trapezoid (the intersections of the sealing gasket 14 adjacent to the measurement cavity 5 with the horizontal cross-section are included in the two bases of the trapezoid). The length of the intersection of the rear clamping frame inner surface 9 with the horizontal cross-section is greater than the length of the intersection of the front clamping frame inner surface 8 with the horizontal cross-section.

[0023] A preferred embodiment of the present invention is that the shape of the measuring cavity 5 in the horizontal cross-section is an isosceles trapezoid, and the vertical plane passing through the midpoints of the two bases is the symmetry plane 25 of the glass plate level gauge. The glass plate level gauge is a symmetrical structure, with the front glass plate 1 and the rear glass plate 2, the front gland 7 and the rear gland 10, and the guide hole 12 and the observation hole 3 having the same shape and size, and being symmetrical with respect to the symmetry plane 25 of the glass plate level gauge. The two side surfaces of the guide hole 12 and the two side surfaces of the observation hole 3 are perpendicular to the symmetry plane 25 of the glass plate level gauge, as shown in FIG. Figure 1 、 Figure 2 and Figure 4 The guide hole 12 and the observation hole 3 can be used interchangeably, that is, the guide hole 12 is used as the observation hole 3, and the observation hole 3 is used as the guide hole 12; in this way, when it is inconvenient to observe at one position, observation can be made at another position.

[0024] The angle C between the front glass exit surface 15 and the rear glass entrance surface 16 is generally 30° to 90°. The symbol "°" represents degrees. The width u of the guide hole 12 is generally 20 to 30 mm, and the width v of the observation hole 3 is generally 20 to 30 mm. U and v are generally the same value. The length of the intersection line between the rear clamping frame inner surface 9 and the horizontal cross-section is generally 30 to 100 mm.

[0025] The front glass plate 1 and the back glass plate 2 are typically made of quartz glass. Their thicknesses are typically 15 to 30 mm, determined primarily by the pressure of the liquid column 18 and the gas within the measurement chamber 5. The thickness of the front glass plate 1 is measured between the front glass incident surface 13 and the front glass exit surface 15, while the thickness of the back glass plate 2 is measured between the back glass incident surface 16 and the back glass exit surface 17.

[0026] The front clamping frame 6, the rear clamping frame 11, the front gland 7, and the rear gland 10 can be made of carbon steel or stainless steel, etc., depending on the corrosiveness of the liquid column 18 and the gas in the measuring chamber 5. The sealing gasket 14 is made of an elastic corrosion-resistant sealing material.

[0027] See also Figure 4 and Figure 3 as well as Figure 1 and Figure 2 The first embodiment of the method for measuring liquid level using the glass plate liquid level gauge of the present invention is as follows: light outside the glass plate liquid level gauge (referred to as external light) is incident on the front glass plate incident surface 13 through the guide hole 12, then enters the front glass plate 1 and passes through the front glass plate 1, and then is emitted from the front glass plate emission surface 15 and enters the measuring cavity 5. The lower part of the measuring cavity 5 is a liquid column 18, and the upper part is gas. The gas is a transparent gas, and the liquid in the liquid column 18 is a transparent liquid. When the light enters the gas above the liquid column 18, a first light ray 19 (such as Figure 4 ), and forms a second light ray 20 (shown as the thick solid line in FIG) when entering the liquid column 18. Figure 4). The first light 19 is the main light, passing through the gas above the liquid column 18; the second light 20 passes through the liquid column 18, and the first light 19 is located above the second light 20. Afterwards, the two light rays enter the rear glass plate 2 from the rear glass plate incident surface 16 and pass through the rear glass plate 2, and then are emitted from different positions on the rear glass plate emission surface 17. Alternatively, the second light 20 is totally reflected at the position where it intersects with the rear glass plate emission surface 17 and does not emit from the rear glass plate 2. Finally, the first light 19 is emitted through the observation hole 3 and at the exit of the observation hole 3 ( Figure 4 At position R in the middle, the human eye, facing the direction of the first light beam 19, can see a vertical light column 22 formed by the first light beam 19 and a dark background 23 below the vertical light column 22, but cannot see the second light beam 20. The level of the liquid column 18 in the measurement cavity 5 is measured based on the vertical light column 22 or the dark background 23. The bottom of the vertical light column 22 or the top 24 of the dark background 23 represents the level of the liquid column 18 and also serves as the boundary between the vertical light column 22 and the dark background 23.

[0028] The light outside the glass plate level gauge is natural light (generally daytime sunlight) and factory lighting (nighttime lighting). The transparent liquid in the liquid column 18 can be colorless (such as water, methanol, or ethanol) or colored (such as gasoline). The gas above the liquid column 18 is air and / or gas evaporated from the liquid in the liquid column 18.

[0029] In the present invention, for the convenience of explaining optical principles and calculations, the first light ray 19 refers to the light ray on the horizontal cross-section plane passing through the gas in the measuring chamber 5 (or refers to the light ray on the horizontal projection plane parallel to the horizontal cross-section plane). In fact, the first light ray 19 located at different heights forms a light plane perpendicular to the horizontal plane. The second light ray 20 refers to the light ray on the horizontal cross-section plane passing through the liquid column 18 in the measuring chamber 5 (or refers to the light ray on the horizontal projection plane parallel to the horizontal cross-section plane). In fact, the second light ray 20 located at different heights forms a light plane perpendicular to the horizontal plane. The external light PO described in the embodiments located at different heights also forms a light plane perpendicular to the horizontal plane. In the present invention, Figure 4 In the figure, the first light 19 and the second light 20 at different heights, the letters and their connections, as well as various angles, distances, and other light rays are all superimposed and projected on a horizontal projection plane. Figure 4 and Figure 2 The meaning of the letters in the figure is shown in the description of the accompanying drawings. It should be noted that the same letters used at different heights are shown in the figure. Figure 4 or Figure 2In fact, the same letters are located at different heights. The above situation can be judged based on the description of the present invention and common sense in the field. In addition, for the sake of clarity, the drawings are not drawn to exact scale.

[0030] See also Figure 4 , the light is refracted when passing through the front glass plate incident surface 13, the front glass plate exit surface 15, the rear glass plate incident surface 16 and the rear glass plate exit surface 17. The meaning of the letters representing the angles of incidence, exit angles, etc., can be found in the description of the accompanying drawings. For various angles of incidence, exit angles, etc., the present invention simply refers to them as angles. The light passes through the normal 21 at each point on the front glass plate incident surface 13, the front glass plate exit surface 15, the rear glass plate incident surface 16 and the rear glass plate exit surface 17. Figure 4 Indicated by dotted line.

[0031] Because the first light ray 19 and the second light ray 20 each form a light plane perpendicular to the horizontal plane, the exit angle difference G described in the accompanying figures is actually the angle between the light plane formed by the first light ray 19 and the light plane formed by the second light ray 20, respectively, upon exiting the rear glass panel exit surface 17. After exiting the rear glass panel exit surface 17, the second light ray 20 generally strikes a side surface of the observation aperture 3 and does not exit through the observation aperture 3. When the second light ray 20 undergoes total internal reflection at the intersection with the rear glass panel exit surface 17, it does not exit through the rear glass panel exit surface 17 or the observation aperture 3. When a small amount of second light ray 20 exits the observation aperture 3, due to the angle G and the position of the first light ray 19 above the second light ray 20, when viewing from position R in the direction of the first light ray 19, only the vertical light beam 22 formed by the first light ray 19 is visible, and the second light ray 20 is not visible. The background of the observation aperture 3 below the vertical light beam 22 formed by the first light ray 19 appears dim. The vertical light column 22 formed by the bright first light 19 is in sharp contrast with the dark background 23 and is easy to observe. Figure 3 .

[0032] Angle C is adjustable. When the shape of the measuring cavity 5 on the horizontal cross-section is an isosceles trapezoid, the glass plate level gauge has a symmetrical structure, and angles K and C are in a fixed relationship of "angle K = angle A = 90° - (180° - angle C) / 2 = angle C / 2," the portion of the first light ray 19 that passes through the gas in the measuring cavity 5 is parallel to the inner surface 9 of the rear clamping frame. At this time, the optical path of the external light that strikes and passes through the front glass plate 1 and the optical path of the first light ray 19 that passes through the rear glass plate 2 and exits from the rear glass plate exit surface 17 are symmetrical relative to the symmetry plane 25 of the glass plate level gauge. The two portions of the first light ray 19 that pass through the gas above the liquid column 18 and are located on either side of the symmetry plane 25 of the glass plate level gauge are symmetrical relative to the symmetry plane 25 of the glass plate level gauge. The value of the exit angle of the first light ray 19 exiting from the rear glass plate exit surface 17 is the same as angle A. Based on the principle of reversible optical paths, the guide hole 12 and the observation hole 3 can be used interchangeably. Under the above conditions, the corresponding relationship between angle C and exit angle difference G can be calculated, as shown in Table 1. Other calculation conditions for the data in Table 1 are: liquid column 18 below measurement chamber 5 is a water column, measurement chamber 5 above liquid column 18 is filled with air, and both front glass plate 1 and rear glass plate 2 are made of quartz glass with a thickness of 30 mm. The data in Table 1 can be calculated using the method described in the embodiments of the present invention.

[0033] As can be seen from Table 1, the larger the angle C, the larger the angle G. When the angle C decreases, the angle G decreases. When the angle C is 0°, the visual effect of the existing ordinary light-transmitting glass plate liquid level gauge will appear, which is not required by the present invention.

[0034] The optimal liquid level resolution can be achieved by calculating the exit angle difference G based on the refractive index of the gas above the liquid column 18 in the measurement chamber 5, the refractive index of the liquid in the liquid column 18, the refractive index of the glass material in the front and rear glass plates 1 and 2, the refractive index of air, and the selected angle C. Under the conditions of calculating the data in Table 1, the angle C is preferably selected between 77° and 90°. In this case, the theoretical calculated value of angle H is greater than 90°. The second light beam 20 undergoes total internal reflection at the intersection with the rear glass plate exit surface 17. The light intensity of the dark background 23 below the vertical light beam 22 is the lowest, and the light intensity difference between the vertical light beam 22 and the dark background 23 is the largest, making it easier to resolve the liquid level. This is an optimized solution of the present invention.

[0035] When the glass plate level gauge has a symmetrical structure, generally, one side of the guide hole 12 and one side of the observation hole 3 are coplanar with the inner surface 8 of the front clamping frame, and the other side of the guide hole 12 and the other side of the observation hole 3 are coplanar with the inner surface 9 of the rear clamping frame. When external light passes through the guide hole 12, the front glass plate 1, and the gas in the measuring chamber 5 to form a first light ray 19, the first light ray 19 in the gas in the measuring chamber 5 will shift toward the inner surface 9 of the rear clamping frame by a distance w. The portion of light in the guide hole 12 that is parallel to the side of the guide hole 12 and close to the inner surface 9 of the rear clamping frame can be reflected by the inner surface 9 of the rear clamping frame when passing through the front glass plate 1 and the gas in the measuring chamber 5. The resulting stray light is emitted from the observation hole 3, affecting the observation effect.

[0036] To address this issue, an optimized solution of the present invention is to roughen the inner surface 9 of the rear clamping frame to form a diffuse reflective layer, or to coat the inner surface 9 with a light-absorbing black coating (not shown). However, when viewing the vertical beam 22 formed by the first light 19 from the exit of the observation aperture 3, the human eye will observe a localized vertical, dark background near the inner surface 9 of the rear clamping frame. The horizontal width of the dark background is equal to w. While this does not affect liquid level measurement, it does affect viewing comfort.

[0037] In order to solve the above problem, a further optimized solution of the present invention is that one side surface of the guide hole 12 and one side surface of the observation hole 3 are still coplanar with the inner surface 8 of the front clamping frame, and the other side surface of the guide hole 12 and the other side surface of the observation hole 3 coplanar with the inner surface 9 of the rear clamping frame are translated toward the inner surface 8 of the front clamping frame (see Figure 2 and Figure 4 ), the translation distance is the translation distance w of the first light beam 19 in the gas within the measurement cavity 5 relative to the external light. The width u of the guide hole 12 and the width v of the observation hole 3 remain both 20-30 mm, but the height of the isosceles trapezoid of the measurement cavity 5 on a horizontal cross-section becomes u + w or v + w. The value of w is a function of angle C and the thickness of the front glass plate 1 and can be calculated using the method described in the Examples. After the above optimization, the width of the vertical light beam 22 observed at the exit of the observation hole 3 is equal to v, providing a comfortable visual experience.

[0038] When the liquid in the liquid column 18 is an opaque liquid, a second embodiment of the method for liquid level measurement using the glass plate liquid level gauge of the present invention is as follows: light from outside the glass plate liquid level gauge is incident on the front glass plate incident surface 13 through the guide hole 12, then enters and passes through the front glass plate 1, and then is emitted from the front glass plate emission surface 15 and enters the measuring chamber 5. The lower part of the measuring chamber 5 is the liquid column 18, and the upper part is gas. The gas is transparent, and the liquid in the liquid column 18 is an opaque liquid that does not adhere to the wall (for example, sewage containing solid impurities). When the light enters the gas, it forms a first light ray 19, and when it enters the liquid column 18, it forms a second light ray 20. The first light ray 19 is located above the second light ray 20. The second light ray 20 is absorbed by the liquid in the liquid column 18 and cannot pass through the liquid column 18. The first light ray 19 passes through the gas above the liquid column 18, then enters the rear glass plate 2 from the rear glass plate incident surface 16, passes through the rear glass plate 2, and is then emitted from the rear glass plate emission surface 17. Finally, the first light 19 is emitted through the observation hole 3. At the exit of the observation hole 3, the human eye can see the vertical light column 22 formed by the first light 19 and the gray background 23 below the vertical light column 22 in the direction of the first light 19. The bottom of the vertical light column 22 or the top 24 of the gray background 23 represents the liquid level of the liquid column 18. The gray background 23 is formed because external light cannot pass through the liquid column 18. The detailed description and drawings of the above-mentioned liquid level measurement method are omitted, and please refer to the attached figure. Figures 1 to 4 The details regarding the symmetrical structure of the glass plate level gauge, the structural parameters and materials of its components, the diffuse reflection layer or light absorption layer on the inner surface 9 of the rear clamping frame, and the side surfaces of the guide hole 12 and the observation hole 3 being coplanar with the inner surface 9 of the rear clamping frame and being translated toward the inner surface 8 of the front clamping frame are the same as those in the case where the liquid in the liquid column 18 is transparent, and are omitted here.

[0039] The present invention ensures that external light passes through the sight glass 12, the front glass plate 1, the gas within the measurement chamber 5, the rear glass plate 2, and the observation hole 3, forming a vertical light column 22 and a dark background 23 below the vertical light column 22, thereby measuring the liquid level of the liquid column 18 within the measurement chamber 5. Whether or how external light can pass through the liquid column 18 does not affect the liquid level measurement, regardless of whether the liquid in the liquid column 18 is transparent or opaque. The present invention does not rely on external light passing through the liquid column 18 to perform liquid level measurement.

[0040] Example

[0041] The glass plate level gauge with symmetrical structure of the present invention is used to measure the liquid level. Figures 1 to 4 The light outside the glass level gauge is natural light; see Figure 4On a horizontal cross-section through the gas in the measurement chamber 5, an external light ray PO passes through the guide hole 12, parallel to the two side surfaces of the guide hole 12. The liquid column 18 at the bottom of the measurement chamber 5 is a water column with a refractive index of 1.333; the measurement chamber 5 above the liquid column 18 is filled with air with a refractive index of 1.00029. The refractive indices mentioned in this invention are relative to a vacuum. The front glass plate 1 and the rear glass plate 2 are both made of quartz glass, each with a refractive index of 1.55 and a thickness of 30 mm. The shape of the measurement chamber 5 in a horizontal cross-section is an isosceles trapezoid. The angle C between the front glass plate exit surface 15 and the rear glass plate incident surface 16, the angle between the front glass plate exit surface 15 and the rear clamping frame inner surface 9, and the angle between the rear glass plate incident surface 16 and the rear clamping frame inner surface 9 are all 60°.

[0042] Angle K is 30°, ∠K = ∠A = ∠C / 2. The portion of first light 19 that passes through the gas above liquid column 18 in measurement chamber 5 is parallel to rear clamping frame inner surface 9. sinA / sinB = 1.55 / 1.00029, yielding ∠B = 18.8°. The angle of first light 19 exiting rear glass plate exit surface 17 is the same as angle A and is parallel to rear clamping frame inner surface 9.

[0043] The second light ray 20 enters the liquid column 18 in the measuring cavity 5 from the front glass plate exit surface 15 at an angle D, where sinD / sinB=1.55 / 1.333. ∠D=22.0°.

[0044] ∠E=90°-{180°-∠C-[(180°-∠C) / 2+∠K-∠D]}=

[0045] ∠C / 2+∠K-∠D=∠C / 2+∠A-∠D=38.0°.

[0046] sinE / sinF=1.55 / 1.333, and we get ∠F=32.0°.

[0047] sinH / sinF=1.55 / 1.00029, and we get ∠H=55.1°.

[0048] ∠G=∠H-∠A=25.1°.

[0049] Calculate as above and combine Figure 4It can be seen that after external natural light in the same vertical direction enters the guide hole 12 and passes through the front glass plate 1, the liquid column 18 and gas in the measurement cavity 5, and the rear glass plate 2, the angle G between the light plane formed by the first light ray 19 and the light plane formed by the second light ray 20 emitted from the rear glass plate exit surface 17 (i.e., the exit angle difference G) is large, and the second light ray 20 is greatly deflected relative to the first light ray 19. At position R, the vertical light column 22 formed by the first light ray 19 can be clearly seen, while the second light ray 20 cannot be seen. Below the vertical light column 22 is a dark background 23.

[0050] The translation of the first light ray 19 is calculated based on the aforementioned liquid level measurement conditions. External light PO strikes the front glass plate incident surface 13, then enters and passes through the front glass plate 1. It then exits the front glass plate exit surface 15 and enters the gas within the measurement chamber 5, forming the first light ray 19. Because the gas within the measurement chamber 5 is also air, the first light ray 19 within the gas within the measurement chamber 5 undergoes a translational shift relative to the external light PO toward the rear clamping frame inner surface 9, a distance w.

[0051] The external light PO intersects the front glass plate incident surface 13 at point O. The normal of the front glass plate incident surface 13 at point O intersects the front glass plate exit surface 15 at point L. The point at which the external light PO enters and passes through the front glass plate 1 and then exits from the front glass plate exit surface 15 is N. The extended line of PO intersects the front glass plate exit surface 15 at point M.

[0052] The area of triangle MNO=1 / 2×MN×LO=1 / 2×MO×w, where LO is the known thickness of the front glass plate 1 .

[0053] w=MN×LO / MO (Formula 1)

[0054] MO = LO / cosA (Formula 2)

[0055] Substituting Equation 2 into Equation 1, we obtain:

[0056] w=MN×cosA (Formula 3)

[0057] sinA=ML / MO=(MN+NL) / MO (Formula 4)

[0058] tanB=NL / LO (Formula 5)

[0059] From Formula 2, Formula 3, Formula 4, and Formula 5, we can get:

[0060] w = LO × (sinA - tanB × cosA). Here, angles A and B are calculated using the method described above for liquid level measurement. The translation distance w of the first light ray 19 is related to angle C and the thickness LO of the front glass plate 1, as shown in Table 2.

[0061] According to the translation distance w of the first light 19, the side of the guide hole 12 and the side of the observation hole 3 coplanar with the inner surface 9 of the rear clamping frame are translated toward the inner surface 8 of the front clamping frame, and the translation distance is w, as shown in FIG. Figure 4 and Figure 2 shown.

[0062] In the examples, the present invention provides some data, and the calculations of other data are performed using EXCEL software based on the given data and the formulas of the examples of the present invention. Except for the data listed in the examples (including the data in Table 1 and Table 2), all other intermediate data calculated in EXCEL software are retained to 8 decimal places after the decimal point.

[0063] When the gases outside the glass plate level gauge and inside the measurement chamber 5 are both common industrial gases (e.g., air, hydrogen, argon, methane, carbon dioxide, nitric oxide, nitrogen, etc.), the difference in refractive index between these gases is very small and essentially negligible. In this case, the first light ray 19 in the gas inside the measurement chamber 5 is substantially parallel to the external light ray PO, and both are perpendicular to the symmetry plane 25 of the glass plate level gauge.

[0064] Table 1

[0065]

[0066] Table 2

[0067] Angle C, unit: ° (degrees) w, unit: mm 0 0 10.0 0.93 20.0 1.88 30.0 2.86 40.0 3.88 50.0 4.97 60.0 6.14 70.0 7.42 76.2 8.26 80.0 8.81 90.0 10.33

Claims

1. A glass plate level gauge, comprising a front glass plate (1), a rear glass plate (2), a front gland (7), a rear gland (10), a front clamping frame (6), and a rear clamping frame (11), wherein the front gland (7) is provided with a guide hole (12), the rear gland (10) is provided with an observation hole (3), the front glass plate (1), the rear glass plate (2), the front clamping frame (6), and the rear clamping frame (11) enclose a measuring cavity (5), and the surface of the front glass plate (1) adjacent to the measuring cavity (5) is the front glass plate The device is characterized in that: the surface of the rear glass plate (2) adjacent to the measuring cavity (5) is the incident surface (16) of the rear glass plate; the surface of the front clamping frame (6) adjacent to the measuring cavity (5) is the inner surface (8) of the front clamping frame; the surface of the rear clamping frame (11) adjacent to the measuring cavity (5) is the inner surface (9) of the rear clamping frame; the inner surface (8) of the front clamping frame, the inner surface (9) of the rear clamping frame, the two side surfaces of the guide hole (12) and the two side surfaces of the observation hole (3) are parallel to each other. The shape of the measuring cavity (5) on the horizontal section is a trapezoid, the intersection lines of the front glass plate exit surface (15) and the rear glass plate incident surface (16) with the horizontal section are the two waists of the trapezoid, the intersection lines of the front clamping frame inner surface (8) and the rear clamping frame inner surface (9) with the horizontal section are the two bottom sides of the trapezoid, and the length of the intersection line of the rear clamping frame inner surface (9) with the horizontal section is greater than the length of the intersection line of the front clamping frame inner surface (8) with the horizontal section; The angle C between the front glass plate emission surface (15) and the rear glass plate incident surface (16) is 30° to 90°; One side of the guide hole (12) and one side of the observation hole (3) are coplanar with the inner surface (8) of the front clamping frame, and the other side of the guide hole (12) and the other side of the observation hole (3) are translated from a position coplanar with the inner surface (9) of the rear clamping frame toward the inner surface (8) of the front clamping frame, and the translation distance is the translation distance w of the first light (19) in the gas in the measuring chamber (5) relative to the external light; The first light (19) refers to light on a horizontal section plane passing through the gas in the measuring chamber (5) or light on a horizontal projection plane parallel to the horizontal section plane; The external light is the light outside the glass plate level gauge; The width u of the guide hole (12) and the width v of the observation hole (3) are still both 20 to 30 mm, but the height of the isosceles trapezoid of the measuring cavity (5) on the horizontal section plane becomes u+w or v+w.

2. The glass plate level gauge according to claim 1, wherein: The shape of the measuring cavity (5) on the horizontal section is an isosceles trapezoid, and the vertical plane passing through the midpoints of the two bottom edges is the symmetry plane (25) of the glass plate level gauge. The front glass plate (1) and the rear glass plate (2), the front pressure cover (7) and the rear pressure cover (10), and the guide hole (12) and the observation hole (3) are symmetrical relative to the symmetry plane (25) of the glass plate level gauge, and the guide hole (12) and the observation hole (3) are used interchangeably.

3. The glass plate level gauge according to claim 1, wherein: The angle C is 77° to 90°.

4. The glass plate level gauge according to claim 1, 2 or 3, characterized in that: The inner surface (9) of the rear clamping frame is provided with a diffuse reflection layer or a light absorbing layer.

5. The glass plate level gauge according to claim 1, wherein: The width u of the guide hole (12) is 20 to 30 mm, the width v of the observation hole (3) is 20 to 30 mm, the length of the intersection line between the inner surface (9) of the rear clamping frame and the horizontal section plane is 30 to 100 mm, the material of the front glass plate (1) and the rear glass plate (2) are both quartz glass, and the thickness of the front glass plate (1) and the thickness of the rear glass plate (2) are both 15 to 30 mm.

6. A method for measuring liquid level using the glass plate liquid level gauge according to claim 1, characterized in that: The light outside the glass plate level gauge is incident on the front glass plate incident surface (13) through the guide hole (12), then enters the front glass plate (1) and passes through the front glass plate (1), and then is emitted from the front glass plate emission surface (15) and enters the measuring cavity (5). The lower part of the measuring cavity (5) is a liquid column (18), and the upper part is gas. The gas is a transparent gas, and the liquid in the liquid column (18) is a transparent liquid. When the light enters the gas, it forms a first light (19), and when it enters the liquid column (18), it forms a second light (20). The first light (19) passes through the gas above the liquid column (18), and the second light (20) passes through the liquid column (18). Then, the two light rays enter the rear glass plate (16) from the rear glass plate incident surface (16) respectively. 2) and passes through the rear glass plate (2), and then is emitted from different positions on the rear glass plate emission surface (17), or the second light (20) is totally reflected at the position where it intersects with the rear glass plate emission surface (17) and does not emit from the rear glass plate (2). Finally, the first light (19) is emitted through the observation hole (3). At the exit of the observation hole (3), the human eye facing the direction of the first light (19) can see the vertical light column (22) formed by the first light (19) and the gray background (23) below the vertical light column (22), but cannot see the second light (20). The bottom of the vertical light column (22) or the top (24) of the gray background (23) represents the liquid level of the liquid column (18).

7. The method according to claim 6, characterized in that: The emission angle difference G is calculated based on the refractive index of the gas in the measuring cavity (5), the refractive index of the liquid in the liquid column (18), the refractive index of the glass material in the front glass plate (1) and the rear glass plate (2), the refractive index of air, and the selected angle C.

8. The method according to claim 6, wherein: The translation distance w of the first light ray (19) in the gas in the measuring cavity (5) relative to the external light ray PO is LO×(sinA-tanB×cosA), where LO is the thickness of the front glass plate (1), A is the incident angle of the light outside the glass plate level gauge onto the incident surface (13) of the front glass plate, and B is the refraction angle of the external light ray from the incident surface 13 of the front glass plate into the front glass plate (1).

9. A method for measuring liquid level using the glass plate liquid level gauge according to claim 1, characterized in that: The light outside the glass plate level gauge is emitted to the incident surface (13) of the front glass plate through the guide hole (12), then enters the front glass plate (1) and passes through the front glass plate (1), and then is emitted from the emission surface (15) of the front glass plate and enters the measuring cavity (5). The lower part of the measuring cavity (5) is a liquid column (18), and the upper part is gas. The gas is transparent gas, and the liquid in the liquid column (18) is opaque liquid. When the light enters the gas, it forms a first light (19). When it enters the liquid column (18), it forms a second light (20). The second light (20) is absorbed by the liquid in the liquid column (18) and cannot pass through the liquid column (18). The first light (19) passes through the gas above the liquid column (18), then enters the rear glass plate (2) from the rear glass plate incident surface (16) and passes through the rear glass plate (2), and then is emitted from the rear glass plate emission surface (17). Finally, the first light (19) is emitted through the observation hole (3). At the exit of the observation hole (3), the human eye facing the direction of the first light (19) can see the vertical light column (22) formed by the first light (19) and the gray background (23) below the vertical light column (22). The bottom of the vertical light column (22) or the top (24) of the gray background (23) represents the liquid level of the liquid column (18).

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