Dynamic Simulation of Natural Gas Filter
Separator Depressurization
Yue Song (B) , Fanpeng Meng, Zhenpeng Hao, Lei Wang, Dan Li, and Shuangjie Yuan
China Petroleum Pipeline Engineering Co.Ltd, HePing Road 146#,
LangFang City 065000, China
sygpll@126.com
Abstract. Under normal conditions, the fluid contents in a natural gas filter separator in a natural gas pipeline will be gas only due to the fine processing in the
conditioning plant. Consequently, most of the time, the filter separator will be an
unwetted vessel. During fires, however, the heat from the fire can be sufficient
to heat the vessel wall until it ruptures, which may lead to a more serious fire.
In view of this problem, a dynamic simulation method was used to calculate the
pressure–temperature curve of the process to verify whether pressure safety valve
can provide enough protection against the combination of high pressure and high
temperature. According to the simulation, depressurization should be used to deal
with the unwetted vessel during fires. Compared with the method in API 521–
2014, the dynamic simulation is more rigorous in calculating the thermodynamic
parameters versus time and can give better sizing results for the depressurization
system.
Keywords: Fire · Nature gas filter separator · Dynamic simulation ·
Depressurization
1 General
API521–2014 provides the estimation method and calculation formula for the gas-phase
fluid discharge capacity when exposed to fire scenarios. The calculation formula is based
on the assumption that the wall temperature and operating pressure of the vessel during
the discharge process should be lower than the allowable stress of the flange and the fluid
temperature in the state of discharge does not change. In the actual project, overpressure
relief of the gas phase is caused by the fire around the vessel, with continuous combustion
of the flame, the temperatures of the vessel wall and of the gas gradually increase with
time. The maximum allowable stress of the vessel nozzle flange may be exceeded by
the operating temperature and pressure in fire conditions, and the flange may shear,
resulting in the discharge of the combustible medium, and increasing the degree of risk
around the vessel. In these circumstances, the operating pressure in the vessel is often
below the safety valve pressure. However, the vessel is damaged due to the sharp rise
in operating temperature and the corresponding reduction in the maximum permissible
stress of the vessel flange. Therefore, the safety valve is only useful in conditions of
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 124–132, 2021.
https://doi.org/10.1007/978-3-030-64690-5_12
Separator Depressurization
Yue Song (B) , Fanpeng Meng, Zhenpeng Hao, Lei Wang, Dan Li, and Shuangjie Yuan
China Petroleum Pipeline Engineering Co.Ltd, HePing Road 146#,
LangFang City 065000, China
sygpll@126.com
Abstract. Under normal conditions, the fluid contents in a natural gas filter separator in a natural gas pipeline will be gas only due to the fine processing in the
conditioning plant. Consequently, most of the time, the filter separator will be an
unwetted vessel. During fires, however, the heat from the fire can be sufficient
to heat the vessel wall until it ruptures, which may lead to a more serious fire.
In view of this problem, a dynamic simulation method was used to calculate the
pressure–temperature curve of the process to verify whether pressure safety valve
can provide enough protection against the combination of high pressure and high
temperature. According to the simulation, depressurization should be used to deal
with the unwetted vessel during fires. Compared with the method in API 521–
2014, the dynamic simulation is more rigorous in calculating the thermodynamic
parameters versus time and can give better sizing results for the depressurization
system.
Keywords: Fire · Nature gas filter separator · Dynamic simulation ·
Depressurization
1 General
API521–2014 provides the estimation method and calculation formula for the gas-phase
fluid discharge capacity when exposed to fire scenarios. The calculation formula is based
on the assumption that the wall temperature and operating pressure of the vessel during
the discharge process should be lower than the allowable stress of the flange and the fluid
temperature in the state of discharge does not change. In the actual project, overpressure
relief of the gas phase is caused by the fire around the vessel, with continuous combustion
of the flame, the temperatures of the vessel wall and of the gas gradually increase with
time. The maximum allowable stress of the vessel nozzle flange may be exceeded by
the operating temperature and pressure in fire conditions, and the flange may shear,
resulting in the discharge of the combustible medium, and increasing the degree of risk
around the vessel. In these circumstances, the operating pressure in the vessel is often
below the safety valve pressure. However, the vessel is damaged due to the sharp rise
in operating temperature and the corresponding reduction in the maximum permissible
stress of the vessel flange. Therefore, the safety valve is only useful in conditions of
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 124–132, 2021.
https://doi.org/10.1007/978-3-030-64690-5_12