Method of estimating gas emissions

The present invention provides a method for estimating the gas emissions to more accurately estimate the emissions of gas from storage tanks of the fixed roof that was stored liquid containing a volatile material. A when estimating how the gas emissions from the storage tank 1 which stores a liquid 31 containing a volatile substance, in the first step, the operation of the tank shape and the relief valve 211 of the storage tank 1 of the fixed roof to set the prerequisites such as pressure, in a second step, to set the content rate of the liquid 31 and gas 32 in the storage tank 1, the temperature, the initial conditions of pressure. 3 The process defines the inflow / outflow amount of heat to the liquid 31 and gas 32 in the storage tank 1, the liquid by CFD analysis - calculated mass transfer amount between the gas, in the fourth step, the relief valve on the basis of the mass transfer amount obtaining emissions of gases from the presence and the relief valve 211 of the operation of 211. .FIELD 1