Calculation of process exhaust gas volume
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I’ve been recently calculating the breathing loss for fixed-roof storage tanks. When dealing with the large-scale breathing losses, I find it difficult to understand the unit of Lw in the formula LW=4.188×10^(-7)×M×P×KN×KC. LW represents the operational loss of a fixed-roof tank (in Kg/m3 of input volume). How should Lw be converted to kg/year? Is it sufficient to simply multiply the input volume by Lw, or is it necessary to multiply it by the volume of the tank as well? First, thank you all for your answers
First, we need to clarify the meaning and units of the parameter LW in the formula LW=4.188×10^(-7)×M×P×KN×KC. Here, LW represents the specific working loss per unit volume of a fixed-roof tank, with the unit being Kg/m3 of input. This means that for every cubic meter of fluid added to the tank (which may refer to the volume of liquid filled in or discharged), LW kilograms of volatile substances are lost. Now, if you want to convert the LW into an annual loss amount in kg/a, you need to consider the following factors: the volume of the storage tank (V, in m3): this is the total capacity of the tank. Number of cycles per year (N, unit: none, just a count): This indicates how many times the tank is filled and emptied each year. Volume per filling or discharge (ΔV, in m3): This is usually a portion of the tank’s capacity, but when calculating large breathing losses, we assume that each filling or discharge corresponds to the entire capacity of the tank, that is, ΔV = V. Based on the factors mentioned above, the annual loss due to breathing (Loss_per_year) can be calculated using the following formula: Loss_per_year = LW × V × N, where LW represents the loss per unit volume of material used (in Kg/m3), V is the volume of the storage tank (in m3), and N is the number of times the tank is used per year (unitless). It should be noted that N depends on the actual usage pattern of the storage tank. For example, if the tank is completely filled and emptied twice a year, then N=2. If the storage tank is only partially filled or emptied, you need to calculate the amount of filling or emptying for each instance based on the actual conditions, and adjust N and ΔV accordingly. However, when calculating the large breathing loss, to simplify the calculations, we usually assume ΔV = V. Finally, regarding the “amount of input” you mentioned, in this context it usually refers to the amount of liquid filled into or discharged from the storage tank. However, when calculating the large breathing losses, we usually focus on the total volume of the tank and the number of annual turnovers, rather than the specific amount put in each time.
LW is the work loss per unit volume (input in Kg/m3). Is there a standard reference table?