What kind of container is a buffer tank? The buffer tank used in oil fields, also known as a horizontal separator buffer tank, belongs to separation containers. This type of container has a larger processing capacity than other types of separation containers with the same specifications. It is widely used in booster stations, transfer stations, combined stations, and centralized processing stations, playing the roles of oil-gas separation, storage, and buffer balance in the process of oil and gas gathering and transportation. ### Principles and Functions of Buffer Tanks #### Working Principle of Buffer Tanks After the oil-gas-water mixed incoming fluid enters the buffer tank, preliminary gas-liquid separation is achieved through collision separation and gravity sedimentation. The separated gas enters the gas-liquid separator, and the separated oil-water mixture enters the oil transfer pump for external transportation or flows into the settling tank through the outlet pipeline. #### Functions of Buffer Tanks - It is mainly used to reduce the pulsating fluctuation of the exhaust gas from piston compressors, enabling the compressor to supply gas as continuously and stably as possible, and reducing the impact of pulsating airflow on pipelines, equipment, and processes. Some buffer tanks are equipped with gas-liquid separation or filtering devices (depending on the compressor, some may not have them) to reduce the impact of impurities entering the compressor on the compressor. - A vacuum buffer tank, also called a negative pressure buffer tank, can be made of stainless steel or carbon steel. The stainless steel vacuum buffer tank is referred to as a stainless steel vacuum tank for short. The function of the vacuum buffer tank is to buffer the pressure fluctuation of the system, make the system work more stably, prevent material backflow, and can also be used for gas-liquid separation to achieve stable vacuum degree (otherwise, the vacuum degree cannot meet the requirements). - Buffer tanks are widely used in central air conditioning, boilers, water heaters, frequency conversion, and constant pressure water supply equipment. They buffer system pressure fluctuations, eliminate water hammer, and play a role in pressure stabilization and unloading. When the water pressure in the system changes slightly, the automatic expansion and contraction of the buffer tank's airbag will buffer the change in water pressure to a certain extent, ensuring stable water pressure in the system and preventing the water pump from starting and stopping frequently due to pressure changes. ### Common Faults, Prevention and Treatment Measures 1. **Oil Leakage from Buffer Tank Safety Valve** - Cause: Failure to control the pressure of the buffer tank, resulting in pressure exceeding the opening pressure of the safety valve. - Prevention measure: Immediately start oil transportation and open the vent valve of the gas-liquid separator to release pressure. 2. **No Alarm for High Liquid Level in Buffer Tank, Crude Oil Entering Gas Pipeline** - Cause: The float of the buffer tank is stuck or the electric contact fails to close. - Prevention measure: Immediately transport oil to lower the liquid level in the pipeline, open the buffer tank bypass, and close the buffer tank inlet valve to stop liquid inflow into the buffer tank. 3. **No Alarm for Low Liquid Level in Buffer Tank, Drop in Oil Transfer Pump Pressure, Pump Failing to Deliver Fluid** - Cause: The lower liquid level float is stuck or the lower liquid level electric contact fails to close. - Prevention measure: Immediately stop the pump, reconfigure the process, then clean the float or repair the electric contact. 4. **Excessively Low Temperature in Buffer Tank** - Cause: The furnace temperature of the heating furnace is too low, resulting in excessively low oil temperature at the primary heating outlet. - Prevention measure: Immediately adjust the heating furnace to increase its temperature. 5. **Excessively High Temperature in Buffer Tank** - Cause: The furnace temperature of the heating furnace is too high, resulting in excessively high oil temperature at the primary heating outlet. - Prevention measure: Immediately adjust the heating furnace to reduce its temperature. 6. **Excessively High Pressure in Buffer Tank** - Cause: The vent valve of the gas-liquid separator is not opened or is opened too slightly. - Prevention measure: Open or fully open the vent valve of the gas-liquid separator. 7. **Excessively Low Pressure in Buffer Tank** - Cause: The vent valve of the gas-liquid separator is opened too much. - Prevention measure: Close the vent valve of the gas-liquid separator slightly. ### Principles for Determining the Size of Buffer Tanks The volume of a buffer tank is comprehensively determined based on factors such as the outlet pressure of the product gas and the volume of the adsorber. Taking a screw air compressor as an example: If the size of the buffer tank is not suitable for the air compressor, it will cause the air compressor to load and unload frequently, and increase the number of times the intake valve is opened and closed. The volume (V) of a suitable buffer tank can be calculated by the following formula (Note: The formula is provided by Atlas series air compressors (Wuxi Atlas, Fuda, Bolait), with a minimum loading and unloading interval time of 30s): V ≥ loading rate × (1 - loading rate) × rated flow of air compressor × atmospheric pressure × air outlet temperature / (2 × loading and unloading pressure difference × air inlet temperature) The meanings of each parameter in the above formula are as follows: - Loading rate: actual gas consumption / rated gas volume of the air compressor; - Rated flow of the air compressor: unit is m³/min; - Air outlet temperature and inlet temperature: in Kelvin (K); - Working pressure of the buffer tank: should be greater than the maximum pressure of the compressed air. It can be seen that before calculating the volume of the buffer tank, it is necessary to confirm the volume of the buffer tank and values such as the loading rate, air compressor flow, set pressure difference, atmospheric pressure at the place of use, and ambient temperature. If the loading and unloading interval time of the air compressor is long, the volume of the buffer tank should also be increased accordingly. ### Major Global Manufacturers of Buffer Tanks - Wessels - Amtrol - Cordivari - Grundfos - Lochinvar Products - Vaughn - Hot Water Products, Inc. - EMIS - Flexcon Industries - AERCO - Niles Steel Tank - Automatic Heating - Cemline The above is an introduction to the relevant knowledge of buffer tanks, hoping to be helpful to everyone. **Article sources**: Changxi Safety Micro-Class, Mabei Micro-Class, Zhongcheng Hangyu CanGas