Liquid Ethylene Atmospheric Storage Tank

Liquid ethylene atmospheric storage tank is an important equipment in liquid ethylene liquefaction plant, reserve station and receiving station. It has the characteristics of large storage volume, low working pressure and high safety factor.

There are two main overall structures of liquid ethylene atmospheric storage tank

1. Single tank (volume ≤ 6000m3) mostly adopts vertical flat bottom, cylinder, double wall, internal and external self vault structure.

2. Single tank (volume > 6000m3) and full tank mostly adopt vertical flat bottom, cylinder, double wall, inner ceiling and outer self arch roof structure, and the outer tank of full tank has hot corner protection layer.

The liquid ethylene is stored in the normal pressure tank, and the interlayer is filled with pearlescent sand. When working, the interlayer is filled with dry nitrogen to ensure that the pearlite is in a dry state for a long time, so that the storage tank has a lower evaporation rate.

Composition of liquid ethylene atmospheric pressure tank: inner tank, outer tank, bottom insulation layer, sandwich insulation layer, equipment ladder platform, equipment valve instrument and foundation platform, etc.

The equipment foundation is overhead type. The whole equipment is located on the reinforced concrete foundation platform. The bottom of the foundation platform is supported by concrete columns. The equipment foundation is ventilated and moisture-proof, and the equipment is erected high.

The inner tank is mainly composed of tank top, cylinder and bottom plate. All parts are made of austenitic stainless steel s30408 to store liquid ethylene.

The outer groove is mainly composed of top cover, cylinder and bottom plate, and each part is made of Q345R steel plate.

The inner and outer roof is of longitude and latitude ribbed vault structure, and the cylinder is of built-in angle steel ring reinforcement structure. The bottom plate is a pressure bearing structure composed of arched edge plate and middle web plate.

Auxiliary structure of equipment: the storage tank is equipped with winding ladder, operation platform and fire-fighting facilities. The surface paint is imported from Jordan, which will not fade and peel for 2 years. The service life of the storage tank is not less than 20 years.

configuration parameter

The storage tank can be customized according to the specific requirements of customers. The general parameters of conventional storage tank are as follows:

Single tank: 200-1000000m3

Process flow system

Liquid inlet system:

Liquid ethylene is sent to liquid ethylene storage tank through vacuum pipe or cold insulation pipe. Before entering liquid ethylene storage tank, it is divided into two ways (top and bottom two liquid feeding methods) to enter the storage tank for storage. The vacuum pipe is used for the outgoing pipeline of the liquid inlet to reduce the cold loss; The annular spray device is adopted for the liquid inlet pipeline entering the storage tank and the top and bottom to ensure the tank is cooled evenly during the first liquid feeding, so as to avoid excessive local temperature difference stress.

Filling system:

Liquid ethylene is discharged through the discharge port at the bottom of the tank, and the outlet pipe of the liquid discharge pipeline adopts vacuum pipe to reduce the cold loss; The discharge pipeline is provided with a normally open low temperature root valve and a remote control emergency shut-off valve. The liquid discharge pipeline is also provided with a gas seal structure inside the equipment, which is led out from the bottom plate of the inner groove, so as to ensure that the liquid can be discharged completely; In order to facilitate the precooling and start-up of the pump, an anti swirl structure is set at the discharge port to avoid the cavitation of the pump.

Bog system:

When the pressure at the top of the inner tank reaches 15kpa, the bog pressure regulating valve opens and ethylene gas enters the bog recovery system.

Self pressurization system:

The storage tank is equipped with self pressurization system. When the pressure in the tank is reduced to 5kpa, the boost control valve opens, and the supercharging system pressurizes the tank. When the pressure reaches 10KPA, the boost control valve is closed.

Air supply system:

If the pressurization system is insufficient, when the gas phase pressure of the inner tank drops to 2KPa, the corresponding air filling valve xv10704 opens, the storage tank is pressurized and the pressure rises to 10KPA, the air filling valve closes;

Nitrogen sealing system of interlayer:

The dry nitrogen enters the interlayer space of the storage tank through self-contained regulating valve and nitrogen flowmeter, and maintains the positive pressure state (less than 0.8kpa), so as to avoid the wet air entering and maintain the good insulation performance of pearlite.

Other systems:

The system of backflow, analysis and sampling, liquid level, pressure measurement system, fire protection system, etc.