Functions of Buffer Tanks in Oil Refining Equipment

The core functions of buffer tanks in oil refining equipment are stabilizing pressure and flow, achieving gas-liquid separation, protecting downstream equipment, optimizing process continuity, and in scenarios such as waste tire/plastic pyrolysis, they also serve the special purposes of impurity sedimentation and oil-gas buffering. Details are elaborated below based on general functions and application-specific roles.

I. General Core Functions

1. Pressure Stabilization and Fluctuation Absorption

• Acting as a pressure reservoir/hydraulic buffer, buffer tanks absorb instantaneous pressure spikes in the system and supplement flow during low-load periods, preventing pressure surges from damaging pipelines and equipment.

• They avoid frequent start-stop cycles of dynamic equipment like compressors and pumps, extending equipment service life and reducing energy consumption.

• Ensure downstream processes operate under stable pressure conditions, enhancing the consistency of product quality.

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2. Flow Balancing and Buffering

   Balance flow discrepancies between upstream and downstream equipment, isolate the propagation of disturbances among system units, and maintain stable continuous operation of the overall process.

• Provide a stable feed rate for subsequent procedures, preventing process disruptions caused by upstream flow fluctuations.

• Classified into suction buffer tanks (reducing flow unevenness in suction pipelines and improving pump suction performance) and discharge buffer tanks (reducing flow unevenness in discharge pipelines and avoiding over-flow issues).

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3. Gas-Liquid Separation and Impurity Removal

• Reduce fluid flow velocity to enable natural separation of gas and liquid phases, preventing liquid from entering compressors, pumps and other equipment and causing liquid hammer damage.

• In waste tire/plastic pyrolysis processes, they can settle solid impurities such as carbon black particles entrained in oil-gas streams, protecting downstream equipment like condensers.

• Provide sufficient residence time to facilitate phase separation of different substances, facilitating subsequent treatment operations.

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4. Safety Protection and Process Assurance

• Prevent water hammer effect (pressure waves generated by sudden fluid stoppage or direction change) from damaging the pipeline system.

• Serve as emergency storage vessels, supplying materials temporarily in the event of supply system failures to avoid production downtime.

• Stabilize the inlet pressure and temperature of compressors, prevent liquid hammer incidents, and protect high-value compression equipment.

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II. Application-Specific Functions in Different Scenarios

1. Fuel Gas Systems

• Stabilize the supply pressure of fuel gas, preventing flame instability or flameout of burners caused by gas pressure fluctuations.

• Store excess fuel gas and release it during peak demand periods to ensure the continuous and stable operation of equipment such as heating furnaces.

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2. Hydrogen Systems

• Smooth pressure fluctuations in the refinery hydrogen network to adapt to feed rate changes and reactor circulation requirements of hydroprocessing units.

• Reduce the number of start-stop cycles of hydrogen compressors, improve system efficiency, and lower maintenance costs.

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3. Waste Tire/Plastic Pyrolysis (Special Functions)

• Used as gas separators to slow down the flow velocity of oil-gas streams, achieve preliminary separation of oil-gas and solid impurities, and prevent condenser clogging.

• Balance the pressure difference between pyrolysis furnaces and condensers, optimizing the oil-gas condensation effect.

• In waste gas treatment systems, act as waste gas collection and buffering devices to stabilize the inlet flow rate of subsequent purification and desulfurization processes.

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4. Reaction Product Systems

• For example, reformate buffer tanks stabilize the flow rate and pressure of reaction products, providing stable raw materials for subsequent processes such as aromatic extraction and fractionation.

• Absorb pressure fluctuations generated during reaction processes, protecting high-precision downstream separation equipment.

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III. Brief Description of Working Principles

Buffer tanks utilize the volume buffering effect, absorbing pressure changes through the compression/expansion of gas or liquid inside the tank. According to medium properties and process requirements, they are divided into two types: direct contact type (where gas and liquid come into direct contact) and diaphragm type (where gas and liquid are separated by a diaphragm, featuring compact size and suitability for applications with high hygiene requirements).