95，on tank discharge and return system -威尼斯2299

on the tank discharge and return system

◆ liquid out of storage tank (loading): each storage tank is equipped with 2 submerged pumps (single flow: ～ 450m) ³/ h. lift: 140m.), the discharge pipe of submersible pump is equipped with remote control pneumatic emergency shut-off valve, lng orifice flowmeter, and return pipeline behind the pump. after each pump column discharge pipe is led out, check valve and root stop valve are installed respectively, and then the discharge pipe is summarized, and an orifice flowmeter and an emergency shut-off valve are installed on the discharge main pipe.

◆ the submersible pump is equipped with a return pipeline after the pump, and a low-temperature regulating valve is set on the return main pipeline after the pump. this pipeline is used as the start-up pipeline of the submersible pump, and it can prevent the tank from rolling, so it can start the pipeline to circulate the low-temperature liquid inside the tank.

bog recovery system

◆ when the gas phase pressure in the storage tank rises to 20kpa (which can be adjusted according to the process package), the low temperature automatic control valve will be opened and the gas will be discharged into the bog heater or low pressure flare to balance the pressure in the storage tank; when the gas-phase pressure in the tank drops to 15kpa (which can be adjusted according to the process package), the low-temperature regulating valve is closed to keep the tank pressure within the safe range.

air supply system

◆ if the gas phase pressure in the storage tank drops to 5kpa, the low temperature automatic control valve on the gas replenishment pipeline will be opened. when the pressure of the storage tank rises to 10kpa, the gas replenishment will be stopped (fine adjustment can be made according to the liquefaction process package) to keep the pressure of the storage tank in a safe range.

eag vent line

◆ when the gas phase pressure in the storage tank is higher than 25kpa, the throttle valve of the vent air conditioner will be opened, and the gas inside the storage tank will be discharged into the low-pressure flare system or the discharge main pipe on the top of the tank to ensure the safety of the storage tank.

◆ the nitrogen seal is set in front of the flame arrester of the discharge pipeline on the top of lng storage tank to prevent the wet air from freezing and blocking the flame arrester.

safety control pipeline

◆ the pressure and vacuum relief valve is an integral part of the tank. two sets of safety vent pipelines are set at the top of the storage tank, and one set of pressure relief valve is equipped, one for use and one for standby. there are always two sets of pressure relief valves in operation. when the gas phase pressure of the storage tank reaches 28kpa, the pressure relief valve will be opened to exhaust and depressurize.

◆ three sets of vacuum suction valves are set on the top of the storage tank, one for use and the other for standby. there are always two sets of suction valves working. when the gas phase pressure of the storage tank reaches -0.3kpa, the suction valve will open to increase the gas phase pressure in the storage tank.