Regarding the temperature of the liquid chlorine vaporizer
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Vaporization of liquid chlorine is carried out using a coil-type vaporizer. However, there are various opinions regarding the temperature of the vaporizer; many people say that the temperature of the water used for vaporization should not exceed 40°C. Is this in line with the requirements specified in GB11984—2008 \"Safety Regulations for Chlorine\" and AQ3014—2008 \"Technical Requirements for Safe Use of Liquid Chlorine\"? For example, according to requirement 5.1.6 of AQ3014—2008 \"Technical Requirements for Safe Use of Liquid Chlorine\", open flames or steam should not be used to directly heat the gas cylinders; instead, warm water at a temperature below 40°C can be used for heating. The “Notice No. 070 issued by the China Chlor-Alkali Industry Association in 2010 regarding the issuance of ‘Guidelines on Safety Facilities and Emergency Response Techniques for Chlorine’” requires that the full vaporization process for liquid chlorine using coil-type or sleeve-type vaporizers be recommended; the vaporization temperature of liquid chlorine should not be lower than 71°C, with a recommended control temperature for hot water of 75–85°C. A special vaporizer (steam-heated) is used, with the temperature not exceeding 121°C. The vaporization pressure is under interlocked control with the feed control valve, while the vaporization temperature is under interlocked control with the steam control valve. ” How high can the temperature of this carburetor actually be set?
Here, the water is hot; in winter the temperature is kept below 50 degrees, while in summer it can reach over 70 degrees, depending on the actual conditions. This is related to the pressure requirements after vaporization
Is high water temperature related to the disposal of nitrogen trichloride?
I’ve also encountered problems; it’s really frustrating. I don’t know which one to refer to.
The design institute specified a vaporization temperature of 85°C, but in actual production, a lower temperature is sufficient to meet the requirements!
I’ve also spent a long time struggling with the issue of the temperature in liquid chlorine vaporizers – is the China Chlor-Alkali Association more professional than the Quality Supervision Bureau?
I work in a design firm too, but it’s a relatively small one； I read some information online about explosions involving liquid chlorine vaporizers; the temperature set for those vaporizers was below 40°C ； Is it worth taking the risk individually, or is the Chlor-Alkali Association more reliable?
The last edit to this post was made by jingsan on 2018-2-8 at 11:26. The control requirements regarding the vaporization temperature of liquid chlorine specified in GB11984—2008 \"Safety Regulations for Chlorine\" are based on the operating conditions involved in pressurizing tank cars and storage tanks during the loading and unloading of liquid chlorine using batch-type vaporizers. Under these conditions, given the use of batch-type vaporizers, if the vaporization temperature is too high, the pressure in the chlorine gas system will exceed the design pressure of the tank cars; therefore, it is stipulated that the temperature of the water used for vaporization must not exceed 40 degrees℃； The operating conditions specified in the Notice No. 070 issued by the China Chlor-alkali Industry Association in 2010, titled \"Guidelines on Safety Facilities and Emergency Measures for Chlorine,\" generally involve the use of tubular (coiled) vaporizers – where the heating medium flows through the shell side while liquid chlorine flows through the tube side. The vaporized liquid chlorine is then used in various equipment such as chlorination reactors; to prevent the accumulation of nitrogen trichloride, the vaporization temperature must not be lower than 71°C.
Since the boiling point of nitrogen trichloride (NCl3) is 71°C, a temperature above 71°C ensures that nitrogen trichloride vaporizes together with liquid chlorine, preventing the accumulation of nitrogen trichloride.
There are problems with both. The national standard specifies a water temperature of 40°C, which is based on the saturated vapor temperature of liquid chlorine at 40°C; in reality, it’s sufficient for the storage tanks and cylinders to not exceed 40°C. The vaporization process in the vaporizer has little to do with the saturated vapor pressure (the association sets this value at above 71°C). If the water used to heat the vaporizer is kept at 40°C or below, either the vaporizer must be very large, or the chlorine gas delivered to the workshop will have a low temperature and will liquefy when exposed to cold outside conditions. Using this water temperature in practice is simply not feasible. The association’s standard is based on the boiling point of nitrogen trichloride, but 71°C is the boiling point at standard pressure, and the conditions inside a vaporizer are by no means at standard pressure. Moreover, a water temperature of 71°C does not represent the temperature inside the carburetor.
In vaporizers that use chlorine in actual production, the water temperature must be raised to 80°C in winter to achieve good vaporization effects; however, attention must be paid to the design pressure of the sleeves and buffers, which needs to be increased accordingly. The water temperature of the carburetor used for unloading must not exceed 40°C.