Case Study | Successful Application of DHE Radar Level Gauge in Heavy Water Tanks

Thread Content

What is heavy water? Heavy water (Deuterium oxide) is a compound composed of deuterium and oxygen. Its molecular formula is D₂O, with a relative molecular mass of 20.0275, which is about 11% higher than that of water (H₂O), whose relative molecular mass is 18.0153; hence it is called heavy water. Heavy water looks very similar to ordinary water; it is a tasteless and odorless liquid, and its chemical properties are the same as well. However, some of its physical properties differ. The density of ordinary water is 1 gram per cubic centimeter, while the density of deuterium water is 1.056 grams per cubic centimeter ； The boiling point of ordinary water is 100°C, while that of heavy water is 101.42°C℃ ； The freezing point of ordinary water is 0°C, while that of heavy water is 3.8°C. Furthermore, ordinary water can nourish life and foster all things, whereas heavy water cannot make seeds germinate. If humans and animals consume heavy water, it can also lead to death. However, the special value of heavy water lies in its applications in nuclear energy technology. To manufacture highly powerful nuclear weapons, heavy water is required as a moderator in nuclear fission reactions, to slow down neutrons, and it can also be used as a material for producing deuterium. Its concentration in ordinary water is about 0.02% (by mass). Due to the significant hazards of heavy water, its level measurement has always been a major issue. How to solve this measurement challenge? The heavy water tank at a chemical plant in Sichuan has a diameter of 1 meter and a height of 1.5 meters; it is made of stainless steel, with heavy water as the medium inside it. Since the tank went into operation, imported radar level gauges have been used for level measurement. The main issue is that the company has been using imported guided-wave radar level gauges to measure the liquid level in the heavy water tanks. However, there are the following issues: 1. High costs. Imported radar level gauges are relatively expensive ； 2. Difficult to repair. Due to the corrosive nature of heavy water, which has a strong effect on rubber products, the sealing materials of guided-wave radar level gauges are easily corroded, leading to leaks. Solution 1: Using instruments – After the failure of the inline guided-wave radar, the user adopted a flat-panel radar level gauge manufactured by Xi’an Dinghua Electronics Co., Ltd., model DHE-RD-5100-5IMC1FCH2MA. Its measurement range is 0–2 meters, with an accuracy of ±3 mm; it can operate in temperatures ranging from -40 to 130°C, and it supports Hart bus protocol output. Features of the DHE-RD-5100-5 radar level gauge: the flange is entirely covered with PTFE material, ensuring that full sealing is achieved once the gauge is connected to the tank. There will be no corrosion of seals as in guided-wave radar. The instrument enables accurate measurements, unaffected by pressure changes, temperature changes, or fluid inflow and outflow. 2. On-site installation 3. Performance: The instrument has been installed on site for over 180 days; it provides accurate level measurement, and the DCS trend displays in the control room are precise, meeting the requirements of automated production. Advantages of using this product: 1. It completely eliminates the significant risks of environmental pollution and production waste caused by overfilling of the tank ； 2. Zero-cost installation ； 3. Easy implementation of remote level monitoring for automated production control ； 4. **It reduces the workload of instrument operators, with instrument maintenance needs approaching zero.