The invention relates to a method and
system for achieving automatic water
cutting and oil return through a
petrochemical storage tank water drainage
pipe. In order to solve the problem of oil entrainment of water
cutting equipment, an automatic water
cutting tank or an automatic water cutting
pipe which communicates with the lower portion of a
storage tank through the water drainage
pipe is used for water cutting, and when the
oil concentration, detected by an oil-water detection sensor, in liquid exceeds a specified value, a water cutting control valve on a water cutting pipeline led out by the automatic water cutting tank or the water cutting pipe is closed by an intelligent controller; when water appears on the lower portion of the
storage tank again, an oil return control valve on an oil return pipe enabling the automatic water cutting tank or the water cutting pipe to communicate with the storage tank is opened and an oil return pump is started by the
intelligent control for oil return, or an oil return pump on an oil return pipe enabling the water cutting tank and a
check valve of the storage tank is opened by the intelligent controller of water cutting equipment for oil return; when a medium, detected by the oil-water detection sensor, is water, the oil return pump is stopped, and the oil return control valve is closed, or the oil return pump is stopped, and the oil return process is completed; and water cutting is conducted after
settling for a certain time or immediately. The method and
system have the advantages that oil cannot adhere to the interior of the pipeline of the automatic water cutting equipment during water cutting, entrainment and adhering of oil do not exist during water cutting, and the water cutting purity degree is high.