One question per day

Under conditions where the pH value of the anode solution in the electrolyzer is between (2 and 4), NCL3 will be produced

Under conditions where the pH value of the anode solution in the electrolyzer is between (2–4), NCL3 will be produced

2~4 2~4 2~4 2~4

Controlling the ammonia content in the brine can reduce the nitric trichloride content in the electrolyzer.

Under the condition that the pH value of the anode solution in the electrolyzer is (2–4)

Under conditions where the pH value of the anode solution in the electrolyzer is between 2 and 4, NCL3 is generated. When the concentration of NCL3 gas in the chlorine gas exceeds 30 g/L, there is a risk of explosion, which poses a threat to safe production.

Under conditions where the pH value of the anode solution in the electrolyzer is between (2–4), NCL3 will be produced

Under conditions where the pH value of the anode solution in the electrolyzer is between (2–4), NCL3 will be produced

Nitric trichloride is a yellow oily liquid at room temperature, with a boiling point of 71°C (the boiling point of liquid chlorine is -34°C). Its relative density is 1.65, and it catches fire and explodes at a temperature of 95°C. NCl3 will be produced under conditions of a pH value of 2–4 in the anode solution of the electrolyzer. jNCl3 is a highly explosive substance. When charging liquid chlorine using the vaporized chlorine process, as the liquid chlorine evaporates in the vaporizer, the separation factor between nitrogen trichloride and chlorine is 6 to 10; that is, the NCl3 content in the gaseous chlorine is 1, while the nitrogen trichloride content in the liquid chlorine is 6 to 10. Therefore, most of the NCl3 remains in the unevaporated liquid chlorine residue. As the total amount of liquid chlorine in the vaporizer decreases as it vaporizes, the concentration of NCl3 remaining in it increases. When this concentration exceeds 5%, there is a risk of explosion. In the liquefaction production of chlorine, the NCl3 content in the chlorine phase should be less than 5%; at high concentrations of NCl3, an explosion can occur with very little energy. When the nitrogen trichloride content in liquid chlorine is 0.05%, if 1 ton of liquid chlorine vaporizes and only 10 kg of liquid remains, then the nitrogen trichloride concentration in the liquid phase becomes as high as 5%. When this remaining liquid evaporates completely, the nitrogen trichloride concentration in the gas phase will also be 5%, posing a risk of explosion. 　2 NCl3 → N2 + 3Cl2. The factors that can cause an explosion of nitrogen trichloride include operations such as opening and closing valves, knocking, impact, liquid impact (from pumping), vaporization using water vapor, as well as open flames and high temperatures. The range of explosion can be as small as a small amount of NCl3 accumulated at the bottom of the valve, leading to an explosion when the valve is operated. The energy generated by the explosion is related to the concentration or amount of NCl3 accumulated; the minimum amount required to cause a harmless popping sound. Traditional liquid chlorine filling is carried out using a vaporizer; due to the limited pressure of liquid chlorine, it is necessary to use (hot water at 45°C) to vaporize the liquid chlorine in order to increase the pressure, before filling it into steel cylinders. With a constant carburetor volume, the detonation temperature of NCl3 can reach 2128°C, and the pressure can reach 536 MPa (the detonation temperature in air is approximately 1700°C). Therefore, even if there are only trace amounts of nitrogen trichloride in liquid chlorine, failing to pay attention to the vaporization temperature (by using steam or an open flame for heating) and the amount of evaporation can pose significant risks. Several explosion incidents caused by this reason have occurred in the country. Using a Lawrence pump to directly pressurize chlorine and fill it into cylinders completely eliminates the aforementioned risks. However, users must avoid using steam or an open flame to directly heat the liquid chlorine in the cylinder during use; at least 5–10 kg of liquid chlorine should remain in the cylinder. Negative pressure or backflow of material inside the cylinder is prohibited (a buffer tank should be used), and the entity responsible for filling the cylinder with liquid chlorine should clean it regularly and inspect it before each filling.