High Quality China Skid Mounted LNG Plant Factories - 140 TPD large LNG liquefaction plant – Hengzhong

Description of each system

Feed gas filtration separation and pressure regulating unit

1）Process description

The feed natural gas from the upstream flows through the pipeline at a pressure of 5.0 ~ 6.0MpaG enters the feed gas inlet filter separator after pressure regulating, and enters the downstream system after separation and metering.

The main process equipment is feed gas filter separator, flowmeter, pressure regulator, etc.

2）Design parameters

Processing capacity: 20×10⁴Nm³/day

Adjustment range: 50% ~ 110%

 Pretreatment system

Feed gas deacidification unit

1）Process description

The feed gas from the upstream enters the deacidification gas unit, which uses MDEA solution to remove acid gases such as CO₂ and H₂S in the feed gas.

Natural gas enters from the lower part of the absorber （absorbing tower） and passes through the absorber from bottom to top; The fully regenerated MDEA solution (lean solution) enters from the upper part of the absorber and passes through the absorber from top to bottom. The reverse flow MDEA solution and natural gas are fully contacted in the absorber, the CO₂ in the gas is absorbed and enters the liquid phase, and the unabsorbed components are led out from the top of the absorber and enter the decarbonization gas cooler and separator. The gas from the decarbonization gas separator enters the feed gas mercury removal unit, and the condensate goes to the flash tank.

The content of CO₂ in the treated natural gas is less than 50ppmv.

The MDEA solution absorbing CO₂ is called rich solution, which is sent to the flash tower, and the natural gas flashed by depressurization is sent to the fuel system. After heat exchange between the flash rich liquid and the solution (lean liquid) flowing out from the bottom of the regeneration tower, raise the temperature to ~ 98 ℃ to the upper part of the regeneration tower, and carry out stripping regeneration in the regeneration tower until the lean degree of the lean liquid reaches the index.

The lean liquid out of the regeneration tower passes through the rich and poor liquid heat exchanger and lean liquid cooler. The lean liquid is cooled to ~ 40 ℃, pressurized by the lean liquid pump and enters from the upper part of the absorption tower.

The outlet gas at the top of the regeneration tower enters the acid gas separator through the acid gas cooler, the gas from the acid gas separator is sent to the acid gas discharge system, and the condensate is sent to the flash separator after being pressurized by the recovery pump.

The heat source of reboiler of regeneration tower is heated by heat transfer oil. The main process equipment of this unit are absorption tower and regeneration tower.