阅读说明：本技术 压力容器液位测量系统及方法 (Pressure vessel liquid level measurement system and method ) 是由 刘志龙 聂常华 徐长哲 杨青松 王海英 胡俊 欧柱 朱志峰 于 2020-06-22 设计创作，主要内容包括：本发明公开了压力容器液位测量系统及方法,测量系统包括压力容器、差压变送器和平衡罐,所述压力容器的下取压口与差压变送器的负压侧连接,压力容器的上取压口与平衡罐连接,所述平衡罐与差压变送器的正压侧连接,所述压力容器的内底部设置有电加热元件,所述压力容器的内部分为区域A和区域B,所述区域A为上部的饱和区域,所述区域B为下部的非饱和区域,所述区域A内布置一个温度传感器,所述区域B布置多个温度传感器,所述平衡罐与差压变送器之间的冷段引压管采用红外成像测温仪测温。本发明通过对压力容器内部进行分区进行密度补偿,解决了现有差压法液位测量导致测量不准确的问题。(The invention discloses a system and a method for measuring the liquid level of a pressure vessel, wherein the measuring system comprises the pressure vessel, a differential pressure transmitter and a balance tank, a lower pressure taking port of the pressure vessel is connected with the negative pressure side of the differential pressure transmitter, an upper pressure taking port of the pressure vessel is connected with the balance tank, the balance tank is connected with the positive pressure side of the differential pressure transmitter, an electric heating element is arranged at the inner bottom of the pressure vessel, the interior of the pressure vessel is divided into a region A and a region B, the region A is a saturated region at the upper part, the region B is an unsaturated region at the lower part, a temperature sensor is arranged in the region A, a plurality of temperature sensors are arranged in the region B, and a cold section pressure guiding pipe between the balance tank and the differential pressure transmitter adopts an infrared imaging thermometer to measure the. According to the invention, density compensation is performed on the inner part of the pressure container in a partitioning manner, so that the problem of inaccurate measurement caused by the liquid level measurement by the existing differential pressure method is solved.)

1. The pressure vessel liquid level measuring system is characterized by comprising a pressure vessel (1), a differential pressure transmitter (2) and a balance tank (3), the lower pressure taking port of the pressure vessel (1) is connected with the negative pressure side of the differential pressure transmitter (2), the upper pressure taking port of the pressure vessel (1) is connected with the balance tank (3), the balance tank (3) is connected with the positive pressure side of the differential pressure transmitter (2), the inner bottom of the pressure container (1) is provided with an electric heating element (4), the interior of the pressure vessel (1) is divided into an area A and an area B, the area A is a saturated area at the upper part, the area B is a lower unsaturated area, a temperature sensor is arranged in the area A, a plurality of temperature sensors are arranged in the area B, and a cold section pressure leading pipe (6) between the balance tank (3) and the differential pressure transmitter (2) measures temperature by adopting an infrared imaging temperature measuring instrument (5).

2. The pressure vessel level measurement system of claim 1, wherein the temperature sensors in zone B are evenly spaced from top to bottom.

3. Pressure vessel level measurement system according to claim 1, wherein the electric heating element (4) is mounted at the bottom inside the pressure vessel (1).

4. A measuring method based on the pressure vessel level measuring system of any one of claims 1-3, characterized by comprising the steps of:

s1, dividing the interior of the pressure container (1) into an area A and an area B, wherein the area A is a saturated area at the upper part, the area B is a non-saturated area at the lower part, one temperature sensor is arranged in the area A, and a plurality of temperature sensors are arranged in the area B;

s2, respectively acquiring the average temperature of the area B, the saturated steam temperature of the area A, the average temperature of the cold section pressure guiding pipe (6) and a differential pressure transmitter value delta P;

s3, compensating the liquid water density by the area B by using the average value measured by a plurality of temperature sensors to obtain a compensated density value

S4 density value through differential pressure transmitter value delta PDensity value ρ_g(T) and Density value

5. A measuring method of a pressure vessel liquid level measuring system according to claim 4, characterized in that the calculation formula of the liquid level L is as follows:

wherein H is the height of the pressure vessel (1); t is the temperature in the pressure vessel (1); g is the acceleration of gravity.

Technical Field

The invention relates to the technical field of measurement and control, in particular to a system and a method for measuring the liquid level of a pressure container.

Background

The pressure vessel is often exposed to high temperature and high pressure during use, and the pressure vessel is directly affected by the high temperature medium in the pressure vessel. In order to ensure the safety and effectiveness of the pressure vessel in use in high temperature and high pressure environments, the measurement of the medium level inside the pressure vessel is a critical task. In industrial application, in order to ensure the smooth proceeding of industrial production and the safety of pressure vessels under high temperature and high pressure, the liquid level state of the corresponding pressure vessel needs to be measured and monitored. At present, liquid level measurement methods are various, and an ultrasonic liquid level measurement method based on an electronic circuit, a liquid level measurement method based on a differential pressure transmitter and the like are available.

Measurement methods based on electronic circuits are often influenced by environments (such as high-temperature and high-pressure environments) and other aspects, and the measurement accuracy needs to be improved, for example, documents of experimental research on liquid level control based on ultrasonic sensors and design of optical fiber Bragg grating variable sensitivity liquid level sensors are disclosed.

The liquid level measurement method based on the differential pressure transmitter is widely applied to liquid level measurement of a pressure vessel, the liquid level measurement based on the differential pressure transmitter improves the liquid level measurement precision by utilizing density fitting, and the existing liquid level measurement based on the differential pressure transmitter completely considers the inside of the pressure vessel as a saturated state for liquid level measurement, so that the measurement accuracy is not high.

Disclosure of Invention

The invention aims to provide a system and a method for measuring the liquid level of a pressure container, which solve the problem of inaccurate measurement caused by the liquid level measurement by the existing differential pressure method.

The invention is realized by the following technical scheme:

the pressure vessel liquid level measurement system comprises a pressure vessel, a differential pressure transmitter and a balance tank, wherein a lower pressure taking port of the pressure vessel is connected with a negative pressure side of the differential pressure transmitter, an upper pressure taking port of the pressure vessel is connected with the balance tank, the balance tank is connected with a positive pressure side of the differential pressure transmitter, an electric heating element is arranged at the inner bottom of the pressure vessel, the pressure vessel is internally divided into a region A and a region B, the region A is a saturated region at the upper part, the region B is an unsaturated region at the lower part, a temperature sensor is arranged in the region A, a plurality of temperature sensors are arranged in the region B, and a cold section pressure leading pipe between the balance tank and the differential pressure transmitter adopts an infrared imaging thermometer to measure the temperature.

When the electric heating element heats the pressure container, the water temperature in the pressure container can be layered, the whole pressure container can not reach a complete saturated state, but the water temperature at the bottom position of the lower part of the pressure container is too low, so that the phenomenon that the space where saturated steam in the pressure container is positioned is similar to a saturated state (the upper part of the pressure container) is presented; the medium water temperature in the pressure vessel is not uniform, and the medium water temperature belongs to an unsaturated state (the lower part of the pressure vessel).

According to the invention, the pressure container is divided into a saturated area (area A) and an unsaturated area (area B), a plurality of temperature sensors are arranged in the unsaturated area with uneven temperature distribution, density compensation is carried out on the unsaturated area by using a temperature average value, the cold-section pressure guiding pipe obtains the temperature distribution value of the cold-section pressure guiding pipe by using an infrared imaging thermometer for measurement, the dynamic average temperature value of the cold-section pressure guiding pipe is obtained by carrying out average calculation on the temperature distribution value, and the density compensation is carried out on the cold-section water to obtain the compensated density value.

Further, the temperature sensors in the region B are arranged at regular intervals from top to bottom.

Further, the electric heating element is arranged at the bottom in the pressure vessel.

A measuring method based on a pressure container liquid level measuring system comprises the following steps:

s1, dividing the interior of the pressure container into an area A and an area B, wherein the area A is a saturated area at the upper part, the area B is a non-saturated area at the lower part, one temperature sensor is arranged in the area A, and a plurality of temperature sensors are arranged in the area B;

s2, respectively acquiring the average temperature of the area B, the saturated steam temperature of the area A, the average temperature of the cold section pressure guiding pipe and the differential pressure transmitter value delta P;

s3, compensating the liquid water density by the area B by using the average value measured by a plurality of temperature sensors to obtain a compensated density valueThe saturated steam density is compensated by the saturated steam temperature in the area A to obtain a compensated density value rho_g(T) the cold section pressure leading pipe adopts a dynamic average temperature value obtained by measurement based on an infrared imaging thermodetector to perform density compensation on cold section water to obtain a compensated density value

S4 density value through differential pressure transmitter value delta PDensity value ρ_g(T) and Density value

The liquid level L in the pressure vessel is calculated.

The invention provides an optimized liquid level measuring method which is improved on the basis of the traditional differential pressure liquid level measuring method and the traditional differential pressure liquid level measuring device. First, the pressure vessel is divided into saturation zonesAnd a non-saturation region. The saturated region is the region where the saturated steam is located, and the temperature obtained by measurement is utilized to measure the density rho of the saturated steam_gPerforming compensation; the unsaturated region is the region where the medium water is located, and the average temperature is utilized to measure the density rho of the medium water_w1And compensating, namely arranging temperature sensors as many as possible in the unsaturated area according to the actual condition, measuring the temperature distribution value of the cold-section pressure guide pipe by using an infrared imaging temperature measuring instrument through the cold-section pressure guide pipe, carrying out average calculation on the temperature distribution value to obtain the dynamic average temperature value of the pressure guide pipe, and carrying out density compensation on the cold-section water to obtain the compensated density value.

Further, the calculation formula of the liquid level L is as follows:

wherein H is the height of the pressure vessel; t is the temperature in the pressure vessel; g is the acceleration of gravity.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the invention further defines the internal state of the pressure container, and adopts different density compensation strategies for media in different states in the pressure container, thereby improving the liquid level measurement accuracy of the pressure container in a high-temperature and high-pressure state, and overcoming the large error caused by the traditional high-temperature and high-pressure liquid level measurement method that the internal part of the pressure container is completely regarded as a saturated state for liquid level measurement.

2. The measuring method can accurately and reliably measure the liquid level of the pressure container in the high-temperature and high-pressure environment, and improves the safety and reliability of industrial production and the pressure container.

3. The measuring method of the invention has simple principle, reasonable design of the measuring device and simple and easy realization on the whole.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a flow chart of a liquid level measurement method of the present invention;

FIG. 2 is a schematic view of a liquid level partition measuring method.

Reference numbers and corresponding part names in the drawings:

1-pressure vessel, 2-differential pressure transmitter, 3-balance tank, 4-electric heating element, 5-infrared imaging thermodetector, 6-cold section pressure guiding tube.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.