Lefilter Batch Type Prolysis Plant Water Seal

In batch-type thermal cracking oil refining equipment, the water seal tank is a structurally simple yet critically important safety and process auxiliary device. It is mainly installed at key nodes such as non-condensable gas transmission pipelines and tail gas outlets of cracking reactors, with its core functions centered on safety protection, gas-liquid separation, and pressure stabilization. The specific functions and working principles are as follows:

Safety Sealing and Backfire Prevention

This is the most core function of the water seal tank. A certain liquid level of clean water is injected inside the tank, and the gas outlet of the non-condensable gas transmission pipeline is submerged below the water surface. During normal transmission of non-condensable gas, the gas breaks through the water layer, overflows the water surface, and then enters the subsequent combustion or treatment system; if backfire occurs in the downstream combustion system, the flame will be completely blocked by the water layer and cannot flash back to the upstream cracking reactor or non-condensable gas storage tank. This fundamentally prevents the combustible gas inside the equipment from being ignited and avoids explosion accidents.

Gas-liquid Separation and Impurity Removal

The non-condensable gas produced by cracking will carry a small amount of uncondensed light oil mist, water vapor, and solid dust impurities. When the gas passes through the water layer of the water seal tank, the oil mist will dissolve in the water, the dust will be adsorbed and settled by the water, and the water vapor will condense upon cooling. Thus, gas-liquid and gas-solid separation are achieved, the non-condensable gas is purified, and the subsequent pipelines, valves or burners are prevented from being blocked or corroded by impurities.

System Pressure Regulation and Overpressure Relief

The water seal tank can set the safety pressure threshold of the system by controlling the height of the water layer. When the pressure inside the cracking system or non-condensable gas transmission pipeline is too high, the high-pressure gas will push open the water layer of the water seal tank and be directly discharged into the flare system or vent pipe, realizing passive overpressure relief and preventing the pipelines or equipment from rupturing due to overpressure. Meanwhile, the stable water layer can also buffer the pressure fluctuations in the pipeline and ensure the stability of non-condensable gas transmission.

Operation and Maintenance Key Points:

Regularly check the liquid level height of the water seal tank and replenish water in a timely manner to maintain the set liquid level; periodically discharge the oil sludge and impurities deposited at the bottom of the tank to avoid pipeline blockage; regularly test the water quality to prevent the water layer from losing its sealing and blocking effect due to excessive oil contamination.