Abstract: A process for dewaxing a petroleum oil stock with a liquid solvent employing direct heat exchange cooling of solvent-oil mixture with an immiscible liquid chilling medium.

Abstract: A furfural refining unit treats heavy sweet charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a flash point temperature analyzer, a sulfur analyzer and viscosity analyzers; all analyzing the heavy sweet charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the solvent flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of the heavy sweet charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers and all the sensors, while the other flow rate of the heavy sweet charge oil and the furfural flow rates is constant.

Abstract: A solvent refining unit treats medium sour charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a flash point temperature analyzer, a sulfur analyzer, a refractometer and viscosity analyzers; all analyzing the medium sour charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the furfural flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of the medium sour charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers, the refractometer and all the sensors, while the other flow rate of the medium sour charge oil and the furfural flow rates is constant.

Abstract: A furfural refining unit treats light sweet charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a flash point temperature analyzer, a sulfur analyzer, and viscosity analyzers; all analyzing the light sweet charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the furfural flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of the light sweet charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers and all the sensors, while the other flow rate of the light sweet charge oil and the furfural flow rates is constant.

Abstract: A furfural refining unit treats heavy sour charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a flash point temperature analyzer, a sulfur analyzer and viscosity analyzers; all analyzing the heavy sour charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the furfural flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of the heavy sour charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers and all the sensors, while the other flow rate of the heavy sour charge oil and the furfural flow rates is constant.

Abstract: A furfural refining unit treats light sour charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a flash point temperature analyzer and viscosity analyzers; all analyzing the light sour charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the furfural flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of its light sour charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers and all the sensors, while the other flow rate of the light sour charge oil and the furfural flow rates is constant.

Abstract: A system controls a furfural refining unit in which the furfural refining unit includes an extractor receiving furfural and charge oil, one of which is at a predetermined flow rate while the other flow rate is to be controlled and providing raffinate and extract mix. The control system includes sensors sensing the flow rate, the gravity, the viscosity, the flash point temperature, the refractive index and the sulfur content of the charge oil. Other sensors sense the flow rate of the furfural and the temperature of the extract mix. The signals from the sensors are provided to control apparatus which controls the other flow rate of the charge oil and the furfural flow rates in accordance with the signals from the sensors.

Abstract: A furfural refining unit treates medium sweet charge oil with a furfural solvent in a refining tower to yield raffinate and extract mix. The furfural is recovered from the raffinate and from the extract mix and returned to the refining tower. A system controlling the refining unit includes a gravity analyzer, a refractometer and viscosity analyzer, all analyzing the medium sweet charge oil and providing corresponding signals, sensors sense the flow rates of the charge oil and the furfural flowing into the refining tower and the temperature of the extract mix and provide corresponding signals. One of the flow rates of the medium sweet charge oil and the furfural flow rates is controlled in accordance with the signals from all the analyzers and all the sensors, while the other flow rate of the medium sweet charge oil and the furfural flow rates is constant.