Dongguan Golden Harvest Boiler Equipment Co., Ltd. in consideration of the fire department response time, the location of effective fire fighting facilities and plant fire fighting conditions, the designer to determine the actual unencumbered time of the vessel, but the lower limit of the total response time should not be less than 15min.

Calculate the time required for the vaporization of all liquids in the vessel, which makes it possible to check the timing and the setting of the safety valves. The following calculation assumes that the liquid level is below the specified effective flame height of 25. Step 1 Calculate the actual liquid volume in the vessel. For simplicity, assume that the volume of the liquid portion of the vessel is proportional to the ratio of the wetted area to the total area, and if the vessel has a receiver its volume should be added.

   V1 = V total (A wetting / A total) (3) Step 2 calculate the time required to vaporize all the liquid in the container. First find the time required for the heated liquid to reach the boiling point: S1=VLQK(Tbp-Tn)Q×60(4) Calculate the time required to gasify the total amount of liquid: S2=VLQKQ×60(5) Step 3 to find the total time required for the liquid to gasify: S=S1+S2(6) If the calculated time is less than 15min, then consider it in terms of a gas container. The safety valve on the vessel is unlikely to prevent the vessel from melting.

   If the calculated time is greater than 15 to 20 min, we are justified in using the wetted surface method. Sizing the safety valve using Eqs. (1) and (2) and adjusting the calculation using Eq. (6) increases the confidence in the metal wall.

Step 4 determines if the vessel pressure can reach the set pressure. In some cases, after the last drop of liquid is vaporized, the vessel pressure may reach its set pressure and the safety valve on the vessel will open. This will be accurate if the vessel set pressure is low. Therefore, in addition to the above time guidelines, the designer should also make a rough calculation of the vessel pressure with one drop of liquid still present.

  Assuming that the internal temperature of the vessel has reached the boiling temperature; that the liquid and vapor inside the vessel are one-component hydrocarbons or other pure substances; and that the vapor is an ideal gas. For the initial gas phase, the number of moles of vapor can be calculated.