## 4 Analysis and Results  
### Risk Assessment Calculation  
In the paper, a storage area of a 500 \(\times\) 104 m\({}^{3}\)/day LNG plant in Huanggang, Hubei Province, was used as an example for safety risk analysis. The feed gas is regulated to 6.94 MPa at the station and transported to the LNG plant via a 3.2 km long DN300 feed gas pipeline. The LNG storage area uses two 30,000 m\({}^{3}\) bimetallic single-volume tanks with an operating pressure of 10 kPa g and a storage cycle is 7.5 days. The tanks are equipped with a safety control system and a fire protection system, with overpressure protection and negative pressure protection. Based on the expert scoring, the impact degree and risk degree of risk factors on LNG leakage accidents were summarized. Using \"high-risk equipment\" as an example, the numerical parameters shown in Table 7 were obtained. The remaining second-level indicators were assessed with the same methodology, and the results are shown in Table 8. The numerical characteristics shown in Table 8 were weighted using Equation (7) to obtain the numerical characteristic values for the first-level indicators. The integrated weights \(\omega_{\text{B}}\) of the first-level indicators calculated by ANP were again iterated into Equation (7) to calculate the numerical parameters of the integrated risk, as shown in Table 9. Then, the weighted integrated cloud model was simulated using MATLAB software (see Figure 11). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**High-Risk Equipment** & **Expert** & **Expert** & **Expert** & **Expert** & **Numerical** & **Weights \(\omega\)** \\  & **1** & **2** & **3** & **4** & **5** & **Characteristics** & **Weights \(\omega\)** \\ \hline LNG tank accessories C21 & 0.5 & 0.7 & 0.6 & 0.8 & 0.7 & (0.6600, 0.1103, 0.0289) & 0.1024 \\ Pipelines C22 & 0.6 & 0.8 & 0.7 & 0.9 & 0.7 & (0.7400, 0.1103, 0.0289) & 0.3629 \\ Safety accessories C23 & 0.8 & 0.9 & 0.9 & 0.7 & 0.8 & (0.8200, 0.0802, 0.0238) & 0.3990 \\ Storage tanks C24 & 0.5 & 0.7 & 0.8 & 0.6 & 0.7 & (0.6600, 0.1103, 0.0289) & 0.1339 \\ \hline \hline \end{tabular}
\begin{tabular}{c} Risk level of High-risk equipment \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Evaluation and numerical characteristics of “High-risk equipment”. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Second-Level Elements** & **Numerical** & **Second-Level Weight** & **Comprehensive** & **Risk Level** \\  & **Characteristics** & **Weight \(\omega\)** & **Risk Level** \\ \hline LNG storage tank area C11 & (0.3600, 0.1103, 0.0289) & 0.7802 & 0.0299 & III \\ LNG impoundments C12 & (0.3600, 0.1103, 0.0289) & 0.0078 & 0.0003 & III \\ LNG torch area C13 & (0.4400, 0.0602, 0.0249) & 0.2121 & 0.0082 & III \\ LNG tank accessories C21 & (0.6600, 0.1103, 0.0289) & 0.1042 & 0.0549 & IV \\ Pipelines C22 & (0.7400, 0.1103, 0.0289) & 0.3629 & 0.1912 & IV \\ Safety accessories C23 & (0.8200, 0.0802, 0.0238) & 0.3990 & 0.2102 & V \\ Storage tanks C24 & (0.6600, 0.1103, 0.0289) & 0.1339 & 0.0706 & IV \\ BOG recycling process C31 & (0.6600, 0.0902, 0.0120) & 0.1114 & 0.028 & IV \\ Refilling processC32 & (0.7000, 0.0501, 0.0499) & 0.1808 & 0.0455 & IV \\ Pressure regulation processC33 & (0.7200, 0.0802, 0.0238) & 0.4008 & 0.1009 & IV \\ The PCS process C34 & (0.6800, 0.0802, 0.0238) & 0.3070 & 0.0773 & IV \\ Unlicensed personnel C41 & (0.7000, 0.0501, 0.0499) & 0.1347 & 0.0146 & IV \\ “Three violators” C42 & (0.7200, 0.0802, 0.0238) & 0.7188 & 0.0777 & IV \\ Special operation personnelC43 & (0.6800, 0.0401, 0.0198) & 0.1466 & 0.0158 & IV \\ Methane C51 & (0.4600, 0.0602, 0.0249) & 0.6527 & 0.0488 & III \\ Nitrogen C52 & (0.3600, 0.0902, 0.0120) & 0.1218 & 0.0091 & III \\ Other hydrocarbons C54 & (0.3600, 0.1103, 0.0289) & 0.2256 & 0.0169 & III \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Risk level of secondary risk elements. Two methods for determining the risk level of cloud drops are the cloud map method and the cloud drop similarity \(\zeta\) comparison [34].