LNG Operating Procedures - Doer Equipment

1、 Preparation before voltage regulation
1. Preparation of tools
Two sets of explosion-proof adjustable wrenches, gloves and protective equipment.
2. Work preparation
(1) Wear labor protection appliances, including anti-static clothing, static shoes, helmets, etc;
(2) Check whether mobile phones, computers and other devices that are easy to cause static electricity have been placed in a safe area, and check whether the surrounding environment is safe and meets the operating conditions;
(3) Before entering the station, touch the electrostatic touch release facility with both hands to release static electricity;
(4) Check whether the explosion-proof wrench and other pressure regulating tools are complete;
(5) Check whether the pressure gauge, level gauge, thermometer, combustible gas detector and safety valve of the storage tank are in normal working condition.
(6) Check whether the pipeline valves, pressure gauges and safety valves are in normal working condition.
(7) Prepare all explosion-proof tools
2、 Gas supply process of LNG tank:
1. Confirm that all valves of the storage tank to be supplied with air are closed except the root valve and emergency shut-off valve of the storage tank.
2. Open the liquid inlet valve at the lower part of the storage tank and the pressurized liquid and gas phase valves, and check that the front and rear valves of the pressurized vaporizer are open.
3. Open the low temperature stop valve in front of the vaporizer to supply air, the normal temperature flange ball valve behind the vaporizer and all valves in the pressure regulating system to be opened.
4. A. When the gas supply is less than 1000-2000Nm3/h, the gas supply requirements can be met by using one tank to discharge liquid;
5. Liquid outlet:
(1) When the tank pressure rises to more than 0.15MPa higher than the outgoing pressure, slowly open the outlet valve to complete the gas supply operation.
(2) Record the number of liquid storage tank and the start time of gas supply.
(3) During gas supply, pay close attention to the change of liquid level and pressure of storage tank, as well as the change of outgoing flow and pressure.
3、 Operating procedures for self pressurization of LNG storage tank
1. During manual operation, open the following valves: pressurized liquid phase valve, pressurized gas phase bypass valve, and liquid inlet valve of the vaporizer, so that LNG can directly enter the self pressurized vaporizer, and then enter the LNG tank after gasification. At this time, the pressure shall be closely observed. When the pressure of LNG tank reaches the required value, close the pressurizing liquid valve.
2. Precautions:
(1) During the operation of LNG storage tank, it must be ensured that the high limit liquid level is ≤ 90% and the low limit liquid level is ≥ 15%.
(2) When the self pressurizing system is operated manually, it is strictly forbidden to leave the site.
(3) When the self pressurizing system is put into operation, the pressure reducing system shall be closed.
(4) During manual operation, it is strictly forbidden to leave the site.
4、 Risk analysis and countermeasures
1. When loading and unloading LNG tankers, operators shall wear masks, anti-static work clothes, anti freezing gloves, etc.
2. When unloading the LNG tanker, it is strictly forbidden to move the vehicle to avoid breaking the loading and unloading hose and causing a large amount of LNG leakage.
3. When there is LNG in the pipeline, the valves at both ends cannot be closed at the same time.
4. It is strictly forbidden to touch or step on low-temperature pipes and facilities.
5. In any case, water, oil, mechanical impurities, etc. shall not enter the pipeline to avoid blocking the pipeline.
6. It is forbidden to knock, bake with fire and spray the frozen parts with water.
7. In order to ensure the safety of the operating environment, operators shall wear labor protection appliances and eliminate static electricity before entering the station. Open fire and non explosion proof tools and electronic equipment are strictly prohibited in the operation area of the station.
8. Strictly implement the operation ticket system and follow the steps of the operation ticket. At least two on-site operators are required, one for operation and one for supervision, to ensure safe operation.
9. Carry out safety education before operation, implement on-site safety precautions, and know how to escape and control dangerous situations in case of danger.
5、 LNG Storage Tank Maintenance Procedures
1. The operators and technicians of the LNG station must be familiar with the structure and principle of the storage tank and carry out LNG related operations in strict accordance with the operating procedures.
2. LNG operators and technicians must be familiar with the performance and principle of tank accessories (pressure gauge, level gauge, thermometer, vacuum test valve).
3. The outer cylinder of LNG storage tank is an external pressure vacuum vessel, and welding operation under negative pressure is strictly prohibited.
4. Regularly check the outer cylinder of the storage tank and observe whether there is ice and frost. In case of any ice and frost, report to the shift leader on duty and the station master in time. The shift leader on duty or the station master shall immediately contact the manufacturer to find out the cause and deal with it immediately. Pay close attention to the change of ice and frost during the treatment process. If the accident tends to expand, immediately pour the tank or stop the filling operation, and close the relevant inlet and outlet emergency cut-off valves.
5. Regularly check the connecting pipes and valves of the storage tank, observe whether there is frost, and report to the shift leader on duty if any problems are found. The shift leader on duty will arrange personnel to deal with them according to the situation.
6. Regularly check the pressure gauge, level gauge and thermometer of the storage tank, and observe whether the displayed value is normal.
7. Regularly check the sealing performance and opening/closing action of connecting valves to ensure normal operation.
8. Regularly calibrate safety valves, pressure gauges, liquid level gauges, thermometers as required to ensure normal operation and timely update the contents of equipment accounts.
9. The outer cylinder of the storage tank shall be regularly protected against corrosion, and the pressure gauge, level gauge and thermometer of the storage tank shall be cleaned and maintained visually.
10. Regularly remove rust and prevent corrosion on the easily rusted parts such as the control three-way valve of the pressure and liquid level control instrument of the storage tank.
11. Check the vacuum degree of the storage tank every year or according to the operation conditions, and master the working conditions of the storage tank.