A brief discussion on level gauges suitable for liquid ammonia storage tanks
Thread Content
Ammonia is an important chemical raw material; to facilitate its transportation and storage, gaseous ammonia is usually converted into liquid ammonia by pressurization or cooling. Liquid ammonia, also known as anhydrous ammonia, is a colorless liquid with a strong, pungent odor. Due to its wide industrial use, corrosiveness, and volatility, liquid ammonia has a high incidence of chemical accidents. In most chemical manufacturing plants, a relatively large amount of liquid ammonia is used. If effective level control of the liquid ammonia in the storage tanks is not achieved, it will **reduce production efficiency and may even lead to safety accidents. So, which type of level gauge can be scientifically and effectively applied in liquid ammonia storage tanks? This article will analyze several common level gauges used in liquid ammonia storage tanks. I. Magnetic Flip Disk Level Gauge The working principle of the magnetic flip disk level gauge is based on three main principles: Archimedes’ law, the principle of magnetic coupling, and the principle of communicating vessels. Since magnetic flap level gauges can display the liquid level in a tank in real time, for ammonia storage tanks, it is recommended to install them in a lateral manner; a flange of appropriate size can be used at the connection point between the gauge and the ammonia storage tank. During installation, please ensure that there are no magnetic materials or iron-containing devices in the surrounding area, as this may affect the accuracy of the instrument’s measurement results; in severe cases, it can even cause malfunctions in the instrument. The lined magnetic flap level gauge is specifically designed for measuring the level of corrosive liquids. During measurement, the magnetic flaps of the gauge move as a result of the movement of the magnetic float, and the position of this float corresponds to the actual level of liquid ammonia. Magnetic flap level gauges feature easy installation and intuitive data display. However, most of the low-cost magnetic flap level gauges available in China still suffer from poor sealing performance. Especially when used in liquid ammonia storage tanks, if the liquid ammonia contains a high level of impurities, it is likely that the magnetic float will get stuck by dirt, preventing the magnetic flaps from rotating properly and thus leading to inaccurate measurement results. The Flap-11 magnetic flap level gauge has been designed to prevent the occurrence of the aforementioned issues. By drawing on the advantages of magnetic flap level gauges produced by other domestic manufacturers, its structural design has been improved, resulting in a protection rating of IP66/67 for the Flap-11 magnetic flap level gauge – this enhances the sealing performance of the gauge. II. Radar Level Gauge The radar level gauge operates on the principle of travel time; it measures the distance from a reference point to the surface of liquid ammonia by transmitting and receiving high-frequency pulse signals. It should be noted that when installing a radar level gauge, it is necessary to avoid the feed inlet of the liquid ammonia tank in order to prevent false reflection echoes from affecting the measurement results ； Furthermore, the radar level gauge should not be installed at the center of the liquid ammonia tank to avoid multiple false echoes interfering with each other and causing signal loss. Radar level gauges feature no direct contact with the medium, a small measurement blind spot, and high accuracy. When installing a radar level gauge, it is necessary to provide mounting holes at the top of the liquid ammonia storage tank. If there are deviations in the measurement values, it is recommended to check whether the probe has developed any scaling, and to clean it promptly ； If the \"wave loss\" phenomenon occurs, it is recommended to increase the height of the empty tank appropriately to eliminate the impact of echoes. The Rada-21 high-frequency pulse radar level gauge utilizes a variety of programmable echo processing algorithms, making it suitable for various complex operating conditions. It also features automatic false echo suppression, which enables intelligent elimination of fixed interference and thus provides reliable assurance for the stable operation of production processes. In summary, the level gauges suitable for use in liquid ammonia storage tanks include magnetic flap level gauges and radar level gauges; however, since different instruments have distinct characteristics, it is recommended that technicians choose the most appropriate measuring instrument based on the actual conditions.
Is using guided-wave radar to measure liquid ammonia more effective than non-contact radar?
Radar madness, intermittent neurosis – these are the three major problems: it reports empty tanks as full, and full tanks as empty; the readings show no activity as if the dog is dead. When using radar on liquid ammonia tanks, once it goes crazy, how can you carry out maintenance and troubleshooting, guys? :lol
For the New Year, big bro wants to give you guys some advice
Liquid ammonia is a volatile medium. The saturated temperatures corresponding to different pressures vary. During use, the pressure in the liquid ammonia tank changes slowly. The float of the magnetic flap level gauge tends to jump around. After the container is cooled, the floating ball jumps much less often, but it still happens occasionally. It cannot be completely cured; I hope an expert can offer some advice.
Is this situation also present in liquid chlorine storage tanks? It turns out that the radar and magnetic flip switches installed originally did have the problem you mentioned – leaks occurring with the magnetic flip switches! Now another external level gauge has been added!
Since liquid ammonia is highly sensitive to temperature, severe evaporation occurs on the surface of the medium in the tank, resulting in large fluctuations in the liquid level and an unclear liquid surface; therefore, radar measurement does not work well. We use flanged differential pressure transmitters for measurement, as well as external-type level gauges. Differential pressure types cannot provide accurate measurements, as the density of liquid ammonia is assumed to be a constant value. However, these instruments are of high quality, easy to calibrate, reliable, have no measurement blind spots, and offer good cost-performance; it’s therefore simple to choose a reputable brand ； The main drawback of external level gauges is the presence of a lower limit blind zone.
Liquid ammonia is highly penetrative and corrosive; when ammonia gas mixes with air in certain proportions, it can explode when exposed to an open flame. Therefore, for measuring liquid ammonia, guided-wave radars with graphite-ceramic seals or pulse radars with process connections are generally used.
Is a radar effective when the dielectric constant is low? Personally, I think double flanges, servo level gauges, magnetostrictive level gauges, float switches, and magnetic flip switches are suitable