Liquid Ethylene Atmospheric Pressure Storage Tank

The liquid ethylene atmospheric pressure storage tank is an important piece of equipment in liquid ethylene liquefaction plants, storage stations, and receiving stations. It features a large storage capacity, low working pressure, and high safety factor.

There are two main overall structures for liquid ethylene atmospheric pressure storage tanks:

1. Single tank (capacity ≤ 6000m3) mostly adopts a vertical flat bottom, cylindrical, double-layer wall, and inner and outer self-arch top structure.

2. Single tank (capacity > 6000m3) and full tank mostly adopt a vertical flat bottom, cylindrical, double-layer wall, inner suspended top, and outer self-arch top structure, where the outer tank of the full tank has a thermal angle protection layer.

The interlayer of the liquid ethylene atmospheric pressure storage tank is filled with pearl sand for insulation, and the bottom interlayer uses foam glass bricks for insulation. During operation, the interlayer is filled with dry nitrogen to ensure that the pearl sand remains dry for a long time, resulting in a lower evaporation rate for the storage tank.

Components of the liquid ethylene atmospheric pressure tank: inner tank, outer tank, bottom insulation layer, interlayer insulation layer, equipment ladder platform, equipment valves and instruments, and foundation platform.

The equipment foundation adopts an elevated style, with the entire equipment resting on a reinforced concrete foundation platform, supported by concrete columns at the bottom of the foundation platform. The equipment foundation is ventilated and moisture-proof, and the equipment is elevated.

The inner tank mainly consists of the tank top, cylinder body, and bottom plate, with all components made of austenitic stainless steel S30408 for storing liquid ethylene.

The outer tank mainly consists of the top cover, cylinder body, and bottom plate, with all components made of Q345R steel plate.

The inner and outer top covers adopt a longitudinal and transverse ribbed arch structure, and the cylinder body uses an internal angle steel ring reinforcement structure. The bottom plate adopts a combination of arch edge plates and middle belly plates for pressure-bearing structure.

Auxiliary structures of the equipment: The storage tank is equipped with a spiral ladder, operation platform, and fire protection facilities. The surface paint uses imported Jordan paint, which does not fade or peel for 2 years, and the storage tank has a service life of no less than 20 years.

Product Details

Configuration Parameters

The storage tank can be customized according to the specific requirements of customers, with the following common parameters for conventional storage tanks:

Single tank container: 200-100000m3

Process Flow System

Liquid Inlet System:

Liquid ethylene is delivered to the liquid ethylene storage tank through vacuum pipelines or insulated pipelines. Before entering the liquid ethylene storage tank, it is divided into two routes (top and bottom inlet methods) for storage. The inlet pipelines are all vacuum pipelines to reduce cold loss; the inlet pipelines to the tank and the top and bottom inlet pipelines use a ring spray device to ensure uniform cooling of the inner tank during the first filling, avoiding excessive local temperature stress.

Filling System:

Liquid ethylene is discharged through the bottom discharge port of the storage tank, and the discharge pipeline uses vacuum pipelines to reduce cold loss; a normally open low-temperature root valve is set on the discharge pipeline, and a remote control emergency shut-off valve is also set. The discharge pipeline also has a gas seal structure inside the equipment, and is led out from under the inner tank bottom plate to ensure complete liquid discharge; to facilitate the pre-cooling and startup of the pump, the discharge port is equipped with an anti-vortex structure to avoid pump cavitation.

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 a self-pressurization system. When the pressure in the storage tank drops to 5KPa, the pressurization control valve opens, and the pressurization system pressurizes the storage tank. When the pressure reaches 10KPa, the pressurization control valve closes.

Supplementary Gas System:

If the pressurization system is insufficient, and the gas phase pressure in the inner tank drops to 2KPa, the corresponding supplementary gas valve XV10704 opens, pressurizing the storage tank, and when the pressure rises to 10KPa, the supplementary gas valve closes.

Interlayer Nitrogen Seal System:

Dry nitrogen enters the interlayer space of the storage tank through a self-regulating valve and nitrogen flow meter, maintaining a positive pressure state (less than 0.8KPa) to prevent moist air from entering and maintain good insulation performance of the pearl sand.

Other Systems:

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