Liquid ethane conveying pipeline pressure protection system and method

Abstract

The invention discloses a liquid ethane conveying pipeline pressure protection system and method. The system comprises forward pressure relief systems and reverse pressure relief systems which are arranged in parallel on trunk line pumps or valve bypasses. According to the system and the method, the pump or valve front pressure increment caused by action of the pumps or trunk line valves in a liquid ethane pipeline or the isolation section pressure increment caused by temperature rise is automatically released into adjacent upstream and downstream trunk lines by stimulating relief devices arranged on the pumps of the valve bypassed so as to prevent overpressure mediums from entering the atmosphere and limit the highest operating pressure of each pipe section. The system and the method havethe advantages that the water hammer overpressure problem under transient operation of a pipeline can be solved, the influence on the strength of the pipeline due to the volume change caused by influence of the temperature of the mediums after shutdown of the pipeline can be avoided, the overpressure mediums are not discharged from the system after being released, and therefore the investment ofaccessory facilities are reduced, and the safety, environmental protection and energy conservation effects can be achieved.

Description

technical field [0001] The invention relates to a pressure protection system and method for a liquid ethane delivery pipeline. Background technique [0002] In recent years, the oil and gas exploration and petrochemical industries have developed rapidly, the condensate gas fields have been vigorously developed, the extraction technology of natural gas auxiliary products has been continuously developed, and the sources, processing and sales of natural gas liquids (NGL) have increased day by day. [0003] The chemical composition of liquid ethane is mainly methane, ethane and propane, among which the mole fraction of ethane can reach about 95%. A typical liquid ethane mixture has a very low bubble point (<-80°C, under normal pressure), and a critical temperature of about 25-35°C, so it is very easy to vaporize after leakage. Liquid ethane has a large latent heat of evaporation and absorbs a large amount of heat when volatilized, which may easily cause frostbite to people i...

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Problems solved by technology

[0005] For liquid ethane pipelines, the above two pressure protection methods have their own disadvantages: for the method of water hammer relief valve and storage tank, in view of the high saturated vapor pressure of liquid ethane at room temperature, the storage tank needs to be designed under pressure In principle, this increases the difficulty and cost of storage tank manufacturing, and also poses a challenge to the safety of storage tanks in remote areas; for the method of pipeline strength protection, as mentioned above, correct judgment of extreme pressure is the premise to ensure pipeline safety, and for For large-diameter pipes, increasing the design pressure may lead to a substantial increase in pipe costs

[0006] At present, there are very few special water hammer release studies on liquid ethane pipeline transportation, reasonable water hammer control methods need to be explored in depth, and at the same time, measures to prevent overpressure caused by the temperature of such a medium with high expansibility also need to be developed

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