Liquid chlorine is a yellow green toxic oily liquid. Its boiling point is -34.6 ℃, and melting point -103 ℃. It vaporizes into gas under normal pressure and can be seriously poisoned by inhaling it into the human body. It has severe irritation and corrosiveness. Chlorine is a very active substance, which can react with most elements (or compounds). Liquid chlorine will not burn, but it can support combustion. Most of the general combustibles can burn in chlorine, and generally flammable or steam can also form explosive mixtures with chlorine.
Liquid chlorine is the basic chemical raw material, which can be used in metallurgy, textile, papermaking and other industries. As the raw material for the synthesis of hydrochloric acid, polyvinyl chloride, plastics and pesticides, liquid chlorine must be stored in a cool, dry and ventilated place, fireproof, sunscreen and heat proof.
Liquid chlorine is highly toxic, corrosive and flammable, as well as the safety requirements for tank farm measurement, the liquid level monitoring of liquid chlorine storage tanks has become a common problem in the chlor alkali industry, especially the liquid level measurement of liquid chlorine storage tanks and liquid chlorine intermediate tanks in ionic membrane caustic soda plants, which has always troubled engineering and technical personnel.
In the early stage of the project, the user used the magnetic flap level gauge on the liquid chlorine storage tank, but after using it for a period of time, the measuring pipe wall was frozen and could not be measured, causing strong corrosion to the medium parts of the instrument, causing instrument failure and leakage risk.
The radar level gauge has high accuracy and can adapt to various harsh measurement environments. The measurement does not depend on environmental factors such as process density, pressure and temperature. It is a relatively good choice. However, it has the same shortcomings as many liquid level measuring instruments:
1. Holes are made in the tank to increase the leakage point
2. Liquid chlorine storage tank is a pressure vessel, and liquid chlorine is a toxic and easy to leak liquid. The design specification stipulates that the opening and flange connection on this kind of equipment must adopt concave convex surface, and the pressure grade must be enlarged. In this way, many instruments do not meet the design specifications because they cannot make concave and convex flanges. Even if the instrument with this kind of flange can be made, the price has increased several times. HS-2000 external ultrasonic liquid level gauge for liquid chlorine completely overcomes the above problems and realizes real non-contact measurement.
During the measurement of HS-2000 intelligent external sticking ultrasonic liquid level gauge, the ultrasonic probe is installed directly below the outer wall (bottom) of the container to be measured. There is no need to open a hole. The installation is simple and does not affect the on-site production. It can realize the accurate measurement of various toxic substances and various pure liquids in high-temperature and high-pressure closed containers. The instrument adopts explosion-proof design to meet explosion-proof requirements.
The external ultrasonic liquid level gauge use advanced signal processing technology and a high-speed signal processing chip. Its signal penetrates the wall of the tank and ultimately achieves completely non-contact measurement of liquid height in hermetic tanks. The ultrasonic sensor probe is installed at the bottom of the tank external surface without need for dirrling holes in the tank. This allows for quick, simple installation that doesn't interrupt the tank operation. Becasue of non-instrusive liquid level measurement, the gauge can be used to acquire accurate liquid level for high pressure hermetical tanks with toxic , highly acidic or alkaline and various types of pure liquids. The liquid level gauge has no requirement to materials of tank. Its robust, engineered design allows it to be used in a wide variety of applications and conditions.
The ultrasonic sensor (probe) is designed to be installed on an external surface of a tank wall without the need to drill holes on the measured tank.
Self-Calibration
This function eliminates accuracy loss due to long term usage.
Infrared Debugging During Operation
This function is especially suitable for conditions where it is dangerous to open the meter cover to debug, making the debugging process simple.
Self-Test
The liquid level meter can self-test its own operating status and hardware conditions, ensuring reliability and stability.
One-Key Recovery
If the liquid level meter is not functioning properly, the user can press the one-key recovery button on the remote control to allow the liquid level meter to return to normal working condition.
On Site Display and Remote Transmitting
The liquid level meter can not only display data on site, but also transmit data to a control room located away from the site via signal wire.
The system kernel of the liquid level meter is based on special ultrasonic processing technology capable of high-speed digital signal processing. After processing, the liquid level value is precise enough that additional CPU analyzing, comparing or judging is unnecessary. Once the CPU acquires the liquid level value, the value is transmitted directly to NVRAM for storage and display. In addition, the liquid level meter can output a 4～20mA standard signal or transmit measurement results to a computer ( or secondary meter ) via an RS-485 interface.
As shown below, during the process of measuring liquid level, the modulated acoustic signal is transmitted from the probe and echoed from the liquid surface. The probe then detects the echoed signal. After going through preprocessing, processing and post-processing, this signal provides the accurate time t directly. The CPU then calculates the liquid level height value through a mathematical model.
h = act/2
h：Liquid level height
a：Correction factor
c：Ultrasound transmitting velocity in liquid
t：Time duration between transmission and reception of ultrasound signal
Working principle of liquid level meter
Measuring range | 3m, 5m, 10m, 20m, 30m |
Display resolution | 1mm |
Short time repetition | 1mm |
Measurement error | ±1‰FS(Excessive wall thickness and temperature/pressure instability may affect measurement precision.) |
Span shift | ±10 m |
Current output | 4～20mA，Max load 750Ω |
Communication interface | RS-485, IrDA |
Operating ambient temperature for liquid level meter | -20℃～+60℃ |
Operating ambient temperature for ultrasonic probe | -50℃～+60℃ (A probe with wider temperature range can be provided upon request） |
Operating ambient humidity | 15%～100%RH |
Explosion proof mark | Ex d ⅡC T6 Gb
|
Housing ingress protection | IP 67 |
Liquid level display | 4 digit OLED display |
Blind area | There is a blind area for the liquid level meter |
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