Method and device for measuring water level of steam heat accumulator based on weighing

Abstract

The invention discloses a weighing-based water level measuring device and method for a steam heat accumulator, and relates to the technical field of heat accumulation equipment and steam boilers, the device is provided with a plurality of weighing sensors or pressure sensors at the bottom of a heat accumulator support column for acquiring the total weight of a spherical tank in real time, and the total weight of the spherical tank is measured by combining the internal real-time temperature and pressure parameters. And establishing a mathematical model to reversely deduce the liquid level height. By analyzing the relation between the geometric volume and the mass of water in the spherical container, the real water level can still be accurately obtained under the condition of boiling or violent fluctuation. The device has the advantages of being simple in structure, stable in measurement, suitable for high-temperature and high-pressure environments and the like, and is particularly suitable for accurate liquid level monitoring scenes of steam heat storage equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat storage equipment and steam boiler, in particular to a method and device for accurately measuring water level under the condition of severe fluctuation of water level in steam accumulator or boiler drum. BACKGROUND

[0002] The measurement of water level in traditional accumulator or drum mostly adopts pressure difference method, capacitive type, ultrasonic wave or radar type liquid level meter. During the charging or discharging process of the accumulator, the surface of the internal water body will boil and cause severe fluctuation, making the liquid surface extremely unstable, and false water level appears. The measurement value of the liquid level meter is difficult to truly reflect the internal water level height, which affects the safe operation of the accumulator. When the water level in the boiler drum fluctuates severely, the measurement value of the water level meter may be inaccurate, and when the actual water level in the drum is too low or too high, the boiler heating surface will be dry or the drum will be full of water. For example, in the initial stage of oxygen blowing by the lance of the converter, a large amount of flue gas is generated instantaneously, which causes a large amount of steam-water mixture to be generated in the waste heat boiler for a short time, enter the drum through the riser pipe, and cause severe boiling of the drum, resulting in false water level. At this time, the drum needs to be replenished with water, which can only rely on the experience of the operator to replenish water, and cannot rely on the data of the drum water level meter to replenish water.

[0003] Therefore, a water level measurement method independent of the stability of the liquid surface is needed, which can obtain accurate water level data even when the liquid surface fluctuates severely. SUMMARY

[0004] The embodiment of the present application provides a water level measurement method and device based on weighing method, a plurality of weighing sensors or pressure sensors are arranged at the bottom of the accumulator support column, the real water level is calculated by real-time monitoring of the total weight of the entire accumulator or drum structure, combining the net weight of the accumulator or drum, the real-time temperature and pressure of the steam and other parameters, and using a mathematical model, so as to overcome the measurement error caused by false water level under the condition of severe fluctuation of water level in the traditional liquid level meter.

[0005] In a first aspect, the present application provides a steam accumulator water level measurement method based on weighing, comprising: obtaining the overall weight of the target, and subtracting the self-weight of the target from the overall weight to obtain the sum of the current water body weight and the steam weight in the steam space; calculating the water density under the current working condition from the temperature and internal medium pressure in the target, and obtaining the steam weight in the steam space from the steam volume and steam density in the target; subtracting the steam weight in the steam space from the sum of the current water body weight and the steam weight in the steam space to obtain the current water body weight; dividing the current water body weight by the water density under the current working condition to obtain the current water body volume, and obtaining the internal water level of the target from the current water body volume.

[0006] In some examples, the obtaining the overall weight of the target comprises: arranging pressure sensors under the n support units in the target to obtain pressure values of the pressure sensors; obtaining forces of the corresponding support units from the pressure values of the pressure sensors, and obtaining the average force by weighted averaging of the forces of the support units; multiplying the average force by n to obtain the overall weight of the target.

[0007] In some examples, the obtaining the steam weight of the steam space from the steam volume in the target and the steam density comprises: taking the steam volume corresponding to the average of the highest water level and the lowest water level in the target design as the steam volume in the target; taking the arithmetic mean of the steam density corresponding to the design heat charging starting condition parameter and the steam density corresponding to the heat charging completion condition parameter as the steam density; obtaining the steam weight of the steam space by multiplying the steam volume in the target by the steam density.

[0008] In some examples, the obtaining the internal water level of the target from the current water volume comprises: obtaining a target liquid level volume function from the internal diameter of the target and the internal water level of the target, and solving the target liquid level volume function to obtain the internal water level of the target.

[0009] In some examples, the method further comprises: filtering the pressure values of the pressure sensors.

[0010] In a second aspect, the present application provides a steam accumulator water level measuring device based on weighing, comprising: a target weight obtaining module for obtaining the overall weight of the target; a first weight obtaining module for obtaining the sum of the current water body weight and the steam weight of the steam space by subtracting the self-weight of the target from the overall weight of the target; a second weight obtaining module for calculating the water density under the current condition from the temperature and the internal medium pressure in the target, and obtaining the steam weight of the steam space from the steam volume in the target and the steam density; a third weight obtaining module for obtaining the current water body weight by subtracting the steam weight of the steam space from the sum of the current water body weight and the steam weight of the steam space; a water level calculating module for obtaining the current water volume by dividing the current water body weight by the water density under the current condition, and obtaining the internal water level of the target from the current water volume.

[0011] In some examples, the target weight acquisition module comprises: a pressure sensor arranged at the lower part of each support unit in the target, used to acquire the pressure value of each pressure sensor, and then to obtain the corresponding support unit stress from the pressure value of each pressure sensor, and to obtain the average stress by weighted average of the stress of each support unit, and to multiply the average stress by n to obtain the overall weight of the target.

[0012] In some examples, the second weight acquisition module is used to take the steam space volume corresponding to the average of the highest water level and the lowest water level in the target design as the steam volume in the target, to take the arithmetic average of the steam density corresponding to the design heat charging starting working condition parameter and the steam density corresponding to the heat charging completed working condition parameter as the steam density, and to obtain the steam weight of the steam space by multiplying the steam volume in the target by the steam density.

[0013] In some examples, the water level calculation module is used to obtain a target liquid level volume function from the target inner diameter and the target internal water level, and to solve the target liquid level volume function to obtain the target internal water level.

[0014] In some examples, the device further comprises: The correction module is used to filter the pressure value of each pressure sensor.

[0015] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects: The steam accumulator or drum water level measurement scheme based on weighing provided by the present application uses a weighing sensor or a pressure sensor to acquire the overall weight of the accumulator or drum, combines temperature, pressure and other parameters, and accurately calculates the real internal water level of the accumulator or drum by means of a mathematical model. The measurement error caused by the false water level of the traditional liquid level meter under the condition of severe water level fluctuation can be overcome. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a schematic diagram of the method provided by the embodiment of the present application; Figure 2 is a schematic diagram of the spherical accumulator implementation provided by the embodiment of the present application, wherein 1 is a spherical tank body, 2 is a support column and a bottom plate, 3 is a weighing sensor or a pressure sensor, 4 is a pressure measuring device, and 5 is a temperature measuring device. Figure 3Figure 1 is a schematic diagram of an embodiment of a horizontal heat accumulator or steam drum provided by the present application, wherein 1 is a horizontal cylinder, 2 is a support, 3 is a load cell or pressure sensor, 4 is a pressure measuring device, and 5 is a temperature measuring device. Figure 4 Figure 2 is a schematic diagram of a device structure provided by an embodiment of the present application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0019] In the following description, specific embodiments of the present application will be described with reference to steps and symbols executed by one or more computers, unless otherwise specified. Therefore, these steps and operations will be mentioned several times by computers, and the computer execution referred to herein includes the operation of a computer processing unit represented by an electronic signal in a structured form. This operation transforms the data or maintains it at a location in the memory system of the computer, which can reconfigure or otherwise change the operation of the computer in a manner known to those skilled in the art. The data structure maintained by the data has a specific characteristic defined by the data format at the physical location of the memory. However, the principles of the present application are described in the above text, which does not represent a limitation, and those skilled in the art will understand that the following steps and operations can also be implemented in hardware.

[0020] The term "module" or "unit" used herein can be regarded as a software object executed on the operating system. Different components, modules, engines and services herein can be regarded as implementation objects on the operating system. The devices and methods herein are preferably implemented in software, and of course can also be implemented in hardware, all within the protection scope of the present application.

[0021] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is further understood that the terms "comprise" (or comprise), "comprises" (or comprises) and "comprising" (or comprises) when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. It is further understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. In addition, the word "connected" or "coupled" as used herein can include wirelessly connected or wirelessly coupled. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0022] In the first embodiment of the present application, a weighing-based steam accumulator water level measurement method is provided, which mainly covers the aspects of sensor arrangement, weight calculation, state parameter correction, water level backstepping model construction, and data processing and error correction, etc. As shown in Figure 1 , the method comprises the following steps: S1: obtaining the overall weight of the target, and subtracting the self-weight of the target from the overall weight to obtain the sum of the current water body weight and the steam space steam weight; S2: calculating the water density under the current working condition from the temperature and internal medium pressure inside the target, and obtaining the steam space steam weight from the steam volume and steam density inside the target; S3: subtracting the steam space steam weight from the sum of the current water body weight and the steam space steam weight to obtain the current water body weight; S4: obtaining the current water body volume by dividing the current water body weight by the water density under the current working condition, and obtaining the internal water level of the target from the current water body volume.

[0023] In the embodiment of the present application, in step S1, first, the sensor needs to be arranged: as shown in Figure 2 For a spherical steam accumulator, 3-6 support columns of the spherical steam accumulator are selected (exemplary description, not limited to be unique), and one pressure sensor is installed at the bottom of each support column. The pressure sensor is fixed to the concrete foundation, and the sensor can measure the vertical force F d , as shown in Figure 3 For a horizontal steam accumulator 1 or a steam drum, a pressure sensor 3 is arranged under each support 2. Wherein, the bottom plate area S d of the spherical steam accumulator is obtained in advance by measurement or design drawing. d The support column or support wall plate area S d of the horizontal steam accumulator or steam drum is obtained. d Then, the force F d of a single support column or support can be calculated.

[0024] In the embodiment of the present application, in step S1, the force Fd of each support is obtained, and then the average force of each support is obtained by weighted average Then, the total weight of the heat accumulator (steam drum) is calculated according to the total number of supports n Mt is the total weight, and Fd is the force of each support. d

[0025] In the embodiment of the present application, in step S1, the current water weight Ms and the steam weight Mq are obtained by subtracting the self-weight M0 of the heat accumulator (steam drum) from the total weight Mt.

[0026] In the embodiment of the present application, in step S2, the temperature and pressure parameters inside the heat accumulator (steam drum) are measured by the temperature measuring device 4 and the pressure measuring device 5 built in the heat accumulator (steam drum), and then the density of water ρs=f(T, P) under the current working condition is calculated according to the temperature and the internal medium pressure by referring to the relevant formula specified by the International Association for the Properties of Water and Steam (IAPWS).

[0027] In the embodiment of the present application, in step S2, the volume of steam is estimated empirically: the steam volume Vq corresponding to the average of the highest water level and the lowest water level of the heat accumulator (steam drum) is taken as the steam volume Vq, and the arithmetic average of the steam density corresponding to the design heating start working condition parameter and the steam density corresponding to the heating completion working condition parameter is taken as the steam density ρq of the steam space, so that the mass Mq of the steam in the steam space can be calculated.

[0028] In the embodiment of the present application, in step S3, the internal water weight Ms of the heat accumulator (steam drum) is calculated as Ms=Mt-Mq.

[0029] In the embodiment of the present application, in step S4, the current water volume V is obtained .

[0030] In the embodiment of the present application, in step S4, the water level of the heat accumulator (steam drum) is calculated: for a spherical heat accumulator, the internal diameter is assumed to be 2R, and the internal water level is assumed to be h. According to the liquid level volume function of a sphere: The value of h is iteratively solved by using numerical methods such as Newton-Raphson method, and the real-time water level height is obtained.

[0031] For a horizontal heat accumulator or steam drum, the internal diameter is assumed to be 2R, and the internal water level is assumed to be h. According to the liquid level volume function of a horizontal container: The value of h is iteratively solved by using numerical methods such as Newton-Raphson method, and the real-time water level height is obtained.

[0032] ​In the embodiment of the present application, the data processing and error correction are also included, that is, the sensor data is cleared of short-term interference by a filtering algorithm, and long-term factors such as thermal expansion of the metal structure and foundation settlement are considered.

[0033] In the second embodiment of the present application, in order to better implement the method provided by the embodiment of the present application, the second embodiment of the present application further provides an apparatus based on the above method. The meanings of the terms are the same as those in the above method, and the specific implementation details can be referred to the description in the method embodiment.

[0034] Please refer to Figure 4 , Figure 4 The structural schematic diagram of the apparatus provided by the embodiment of the present application is shown in the figure, wherein the apparatus can include a target weight acquisition module, a first weight acquisition module, a second weight acquisition module, a third weight acquisition module, and a water level calculation module, wherein: The target weight acquisition module is configured to acquire the overall weight of the target. The first weight acquisition module is configured to subtract the self-weight of the target from the overall weight of the target to obtain the sum of the current water body weight and the steam space steam weight. The second weight acquisition module is configured to calculate the water density under the current working condition according to the temperature and the internal medium pressure in the target, and obtain the steam space steam weight according to the steam volume and the steam density in the target. The third weight acquisition module is configured to subtract the steam space steam weight from the sum of the current water body weight and the steam space steam weight to obtain the current water body weight. The water level calculation module is configured to obtain the current water body volume by dividing the current water body weight by the water density under the current working condition, and obtain the internal water level of the target according to the current water body volume.

[0035] The specific implementation of each module can be referred to the description of the above method embodiment, and the embodiment of the present application will not be repeated.

[0036] In the third embodiment of the present application, eight supports are arranged at the bottom of the spherical steam accumulator (volume 650 m³, diameter 10.7 m), and a weighing sensor is arranged at the bottom of each support, the maximum range of which is 150 tons, the output of each sensor is read through a multi-channel acquisition instrument, and the total mass of the spherical accumulator is calculated in real time.

[0037] Firstly, the empty tank mass M0 is recorded and compared with the theoretical weight to calibrate the weighing sensor, then the normal temperature water with a known weight is added, and the sensor is further calibrated according to the real-time calculation weight. In the actual operation process, the internal temperature and pressure of the accumulator are monitored in real time, the real-time is calculated by referring to the international water density standard table. Thus, the current water level is iteratively solved by combining the spherical geometric formula.

[0038] Water level calculation example: spherical heat accumulator charging parameter: 3.2Mpa / 237℃, heat release parameter 1.7Mpa / 204℃, charging parameter corresponding steam density 16kg / m3, heat release parameter corresponding steam density 8.6kg / m 3 , the average density of the steam space is (8.6+16) / 2=12.3kg / m 3 , the average volume of the steam space Vq=146m 3 , the average weight of the steam space Mq=146x12.3=1795.8kg=1.8t, the initial weight of the heat accumulator M0=250t. Now the measured pressure of the heat accumulator is 2.5Mpa, the temperature is 223℃, the total weight of the heat accumulator is Mt=660t, the water level gauge reading is 2.4m, and the saturated water density is 835kg / m 3 according to the above parameters, then the water body weight Ms=660-250-1.8=408.2t, the water body volume , using the formula , the actual water level of the heat accumulator h=1.952m is obtained by iteration.

[0039] Similarly, a weighing sensor can also be installed on the horizontal heater and the steam drum support, and the real water level of the horizontal heat accumulator and the steam drum can be obtained by referring to the above process and calculation method. Here, it is not necessary to repeat the details.

[0040] The above describes in detail a steam heat accumulator water level measurement method and device based on weighing provided by the embodiments of the present application, the principles and implementation manners of the present application are described by applying specific examples in this paper, and the above embodiment description is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed, and in summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method of measuring the level of a steam accumulator based on weighing, characterized in that, The method comprises the following steps: obtaining the overall weight of the target, and subtracting the self weight of the target from the overall weight of the target to obtain the sum of the current water weight and the steam weight in the steam space; calculating the water density under the current working condition according to the temperature and the internal medium pressure in the target, and obtaining the steam weight in the steam space according to the steam volume in the target and the steam density; subtracting the steam weight in the steam space from the sum of the current water weight and the steam weight in the steam space to obtain the current water weight; obtaining the current water volume by dividing the current water weight by the water density under the current working condition, and obtaining the water level in the target according to the current water volume.

2. The method of claim 1, wherein, The overall weight of the target is obtained by the following steps: pressure sensors are arranged at the lower parts of n supporting units in the target, and the pressure values of the pressure sensors are obtained; the forces of the corresponding supporting units are obtained according to the pressure values of the pressure sensors, and the average force is obtained by weighted averaging of the forces of the supporting units; the overall weight of the target is obtained by multiplying the average force by n.

3. The method of claim 2, wherein, The steam weight in the steam space is obtained according to the steam volume in the target and the steam density by the following steps: the steam space volume corresponding to the average of the highest water level and the lowest water level in the target is taken as the steam volume in the target; the arithmetic average of the steam density corresponding to the design heat charging starting working condition parameter and the steam density corresponding to the heat charging completed working condition parameter is taken as the steam density; the steam weight in the steam space is obtained by multiplying the steam volume in the target by the steam density.

4. The method of claim 3, wherein, The water level in the target is obtained according to the current water volume by the following steps: a target liquid level volume function is obtained according to the inner diameter of the target and the water level in the target, and the water level in the target is obtained by solving the target liquid level volume function.

5. The method according to any one of claims 2 to 4, characterized in that, The method further comprises the following steps: the pressure values of the pressure sensors are filtered.

6. A weighing-based steam accumulator water level measuring device, characterized by The method comprises the following steps: a target weight obtaining module is configured to obtain the overall weight of the target; a first weight obtaining module is configured to subtract the self weight of the target from the overall weight of the target to obtain the sum of the current water weight and the steam weight in the steam space; a second weight obtaining module is configured to calculate the water density under the current working condition according to the temperature and the internal medium pressure in the target, and obtain the steam weight in the steam space according to the steam volume in the target and the steam density; a third weight obtaining module is configured to subtract the steam weight in the steam space from the sum of the current water weight and the steam weight in the steam space to obtain the current water weight; a water level calculating module is configured to obtain the current water volume by dividing the current water weight by the water density under the current working condition, and obtain the water level in the target according to the current water volume.

7. The apparatus of claim 6, wherein, The target weight obtaining module comprises pressure sensors arranged at the lower parts of n supporting units in the target, which are configured to obtain the pressure values of the pressure sensors, then obtain the forces of the corresponding supporting units according to the pressure values of the pressure sensors, obtain the average force by weighted averaging of the forces of the supporting units, and obtain the overall weight of the target by multiplying the average force by n.

8. The apparatus of claim 7, wherein, The second weight obtaining module is configured to take the steam space volume corresponding to the average of the highest water level and the lowest water level in the target as the steam volume in the target, take the arithmetic average of the steam density corresponding to the design heat charging starting working condition parameter and the steam density corresponding to the heat charging completed working condition parameter as the steam density, and obtain the steam weight in the steam space by multiplying the steam volume in the target by the steam density.

9. The apparatus of claim 8, wherein, The water level calculation module is configured to obtain a target liquid level volume function from the target inner diameter and the target internal water level, and to solve the target liquid level volume function to obtain the target internal water level.

10. The apparatus of any one of claims 7 to 9, wherein, The device further comprises: The correction module is configured to filter the pressure values of the pressure sensors.

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