Low-temperature issue of liquefied gas rejection during the regeneration of molecular sieve adsorption beds

Regarding the low-temperature issue associated with the withdrawal of liquefied gas, the following aspects can be considered: 1. Heating nitrogen: When using high-pressure nitrogen to push out the liquefied gas, it is possible to heat the nitrogen to a certain temperature, thereby reducing the low-temperature problems encountered during the withdrawal process. However, it is necessary to pay attention to controlling the heating temperature so as not to exceed the limit temperature of nitrogen. 2. Using other inert gases: In addition to nitrogen, other inert gases such as argon can also be used to displace liquefied gas. These gases can also have their temperature controlled by heating, in order to reduce low-temperature issues. 3. Use of hot hydrogen: It is not recommended to use hot hydrogen to push out liquefied gas, as hot hydrogen poses an explosion risk and requires extreme caution when handling it. If hot hydrogen is used, strict safety measures must be taken, and the operation should be carried out under the guidance of professionals. In summary, to address the issue of low temperature during the liquefied gas withdrawal process in the regeneration of molecular sieve adsorption beds, an appropriate method should be selected based on specific circumstances, while also paying attention to relevant safety measures. .

Received. Thank you. Considering hot nitrogen, it is necessary to add heat exchangers, and these must be heat exchangers with a high pressure rating, resulting in a greater risk of leakage. Hot hydrogen stripping is widely used in desulfurization; it can be supplied directly from the compressor outlet. The main concern is that hydrogen has a very low tolerance – any leakage point can lead to ignition, posing a significant risk. . Taking the teacher’s advice into account, consider using an existing heat exchanger to heat the nitrogen; although it requires more energy, it is safer in terms of operation.

Design issues or operational issues should be distinguished, and then corrective measures should be discussed. If it’s a simple issue related to nitrogen temperature, it should have been addressed at the design stage, for reference only.

Determined by the unloading speed, the nitrogen flow rate during unloading is very low, and its specific heat capacity is minimal; thus, the amount of heat carried by just a few dozen cubic meters of nitrogen per hour can be practically disregarded. Each time, the material return takes about half a month. The ideal solution for now is to improve the material of the tank so that it can withstand low temperatures. Or heat tracing can be added inside the tank; it’s difficult to use ordinary materials like Q345 for this purpose

1) When designing the LPG molecular sieve adsorption bed system, it is necessary to consider installing appropriate LPG vapor equilibrium pipes at the top of the adsorption bed to facilitate pressure maintenance during material discharge. This helps to reduce the loss of material due to gasification during discharge and to avoid potential low temperatures in the vapor phase. 2) The molecular sieve adsorption bed regeneration system is generally equipped with devices such as nitrogen circulation fans, heaters (which may also include electric heaters), coolers, and separators, in order to carry out operations such as \"cold blowing – hot blowing – high-temperature regeneration – cooling\" after the material has been removed from the adsorption bed. The capacity of devices like the circulation fans and heaters is usually sufficient to raise the temperature of the adsorption bed to over 200 degrees within a few hours (≯10 hours), thereby enabling the high-temperature regeneration of the molecular sieve adsorbent. A properly designed recycling system will not experience the situation described by the poster.