Abstract:
A method is described for evaporating liquid samples contained in sample holders mounted within a chamber and rotated by the rotor during an evaporation process in which the pressure in the chamber is reduced below atmospheric and the sample holders are rotated at high speed so as to exert centrifugal force on the contents of the holders. Heat is supplied to elevate the temperature of the liquid component of the samples to assist in the evaporation process. The temperature of the sample material is continuously or regularly monitored during the evaporation process and temperature signals are transmitted to a remote computing means which is programmed to generate a control signal for controlling the supply of heat to the samples and controlling the evaporation process. The temperature may be sensed by a probe in a sample holder containing an evaporating liquid sample, or in an adjoining sample holder containing a buffer liquid. The rotational speed is also sensed and a speed signal conveyed to the computing means. In an alternative method the rate of flow of vapor from the chamber is monitored and a flow rate signal is computed which is also supplied to the computer means and the evaporation process is controlled in relation to the value of the vapor flow rate signal. Improved methods of heating and means for supporting sample holders which are to be heated, to achieve more uniform heating thereof, within an evaporating chamber, are described. Apparatus for performing the various methods is also described.
Abstract:
A centrifugal evaporator is described comprising a chamber in which sample containers are carried and rotated by a rotor and are pivotally mounted so as to swing up into a horizontal attitude as the rotor rotates. The evaporator includes an infra red source to direct infra red radiation towards the rotor and the sample containers carried thereon, to heat at least the latter and any sample material therein. A non-contact temperature sensing infra red pyrometer having a sensor with a defined field of view is mounted in the chamber, such that while the rotor as such is substantially out of its field of view, each sample container at least partly occupies the pyrometer field of view for a part of each rotation of the rotor. The positions of the infrared source and the pyrometer components are selected so that the radiation from the infra red source does not impinge on the pyrometer sensor. In particular the infra red source radiation predominantly impinges on the sample containers rather than the rotor. The position of the pyrometer sensor is chosen so that the rotor does not protrude into the pyrometer field of view. The direction of rotation of the rotor is such that any debris thrown from the rotor is directed away from the sensor. Temperature sensing means measures the temperature of the chamber, the pyrometer sensor body and the body of the chamber temperature sensor. Electrical signal processing means receives signals from the IR pyrometer sensor and the temperature sensing means to adjust the temperature values from the IR pyrometer sensor to take account of the chamber temperature, and sensor body temperature.
Abstract:
A method of concentrating chemicals for semiconductor devices, which includes the steps of heating a sample container by using a high-energy light source, vaporizing the chemicals by injecting a high-temperature gas into the sample container through an injection opening in the sample container and discharging the vaporized chemicals by the pressure of the gas through a gas outlet formed on the sample container. An apparatus of concentrating chemicals for semiconductor devices includes a sample container having a sample-supply window, a gas-injection opening and a gas outlet. A high-energy light source heats the sample container and a gas-supply source supplies the gas through a gas-injection opening in the sample container. A gas-heating device located between the sample container and the gas-supply source heats the gas provided by the gas-supply source.
Abstract:
This invention relates to an apparatus and method for evaporative concentration of aqueous solutions and slurries which utilizes as the evaporative unit a wet-wall direct heat exchange evaporator. In a preferred embodiment, an open flame jet operates within a descending liquid vortex, radiant heat being transferred from the flame to the liquid on the walls of the evaporator, and the hot combustion gases being intermixed with the exiting liquid for sensible heat transfer. By special means and method steps scale formation is avoided and the solids are precipitated in filterable form. The apparatus and method are particularly adapted for the restorative processing of spent aqueous sulfuric acid pickling liquors which contain high concentrations of metal salts, including salts such as ferrous sulfate, which exhibit reverse solubility characteristics.
Abstract:
A process for removing volatile substances from viscous compositions, for example, removing volatile solvent and unreacted monomer from polystyrene. The composition is heated to a temperature above the boiling points of the volatile substances at the pressure employed in the operation. The composition is then formed into strands and the strands are impacted against a solid surface. The composition is then caused to flow as a film over a heated surface while the strands and film are exposed to sub-atmospheric pressure.