Disclosed is a urea finishing method including an off-gas treatment, the method comprising urea finishing and supplying the off-gas to a quenching zone and to a scrub column comprising a sump and a venturi stage, wherein the sump has a split sump configuration with two compartments.

Disclosed is a urea finishing method including an off-gas treatment, the method comprising urea finishing and supplying the off-gas to a quenching zone and to a scrub column comprising a sump and a venturi stage, wherein the sump has a split sump configuration with two compartments.

Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 25 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m.sup.3/h)/(m.sup.3/h).

Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 25 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m.sup.3/h)/(m.sup.3/h).

System and methods for solder flux removal from a gas stream is disclosed. In one aspect, the system includes: a scrubber chamber having a gas inlet and a gas outlet through which the gas stream is introduced into and withdrawn from the scrubber chamber; at least one rinse agent delivery mechanism for introducing a rinse agent into the scrubber chamber for contact with the gas stream, the rinse agent being at a temperature for condensing a first portion of the flux from the gas stream; a condenser portion of the scrubber chamber containing the rinse agent for receiving the gas stream, the rinse agent being at a temperature for condensing a second portion of the flux in the gas stream; and a condensed flux removal apparatus adapted for removal from the scrubber chamber of at least a portion of the rinse agent and the flux which has condensed.

A method for collecting particles or gaseous chemicals is provided. The method includes providing liquid to a tube of a droplet generator, heating, with a heater of the droplet generator, the tube to provide vapor to a gas flow channel inside the tube, passing a gas flow containing the particles or gaseous chemicals through the gas flow channel inside the tube to obtain droplets including the particles or gaseous chemicals, and passing the droplets including the particles or gaseous chemicals to a wall of a collecting device such that the droplets including the particles or gaseous chemicals hit the wall. The temperature inside the gas flow channel is higher than a temperature inside the collecting device.

A method for collecting particles or gaseous chemicals is provided. The method includes providing liquid to a tube of a droplet generator, heating, with a heater of the droplet generator, the tube to provide vapor to a gas flow channel inside the tube, passing a gas flow containing the particles or gaseous chemicals through the gas flow channel inside the tube to obtain droplets including the particles or gaseous chemicals, and passing the droplets including the particles or gaseous chemicals to a wall of a collecting device such that the droplets including the particles or gaseous chemicals hit the wall. The temperature inside the gas flow channel is higher than a temperature inside the collecting device.

This invention is directed to an air purification method capable of removing small aerosols and a wide size range of aerosols, with minimum aerosol radius smaller than 0.01 micron. The method humidifies the air in an enclosed space and produces supersaturation at a level of at least 12 percent in at least a portion of the enclosed space so that water vapor condenses on aerosols to form water droplets. The method also coalesces the water droplets formed by supersaturation using coalescence devices that can coalesce droplets with minimum radius smaller than 0.01 micron, thereby lowering the equilibrium supersaturation, enabling water droplets to grow faster, be more stable and easier to be removed compared to when coalescence is absent. The method dehumidifies the air so that the water droplets with captured aerosols are removed. Coalescence enables droplets to grow under a lower ambient supersaturation level, thus saving a considerable amount of energy.

This invention is directed to an air purification method capable of removing small aerosols and a wide size range of aerosols, with minimum aerosol radius smaller than 0.01 micron. The method humidifies the air in an enclosed space and produces supersaturation at a level of at least 12 percent in at least a portion of the enclosed space so that water vapor condenses on aerosols to form water droplets. The method also coalesces the water droplets formed by supersaturation using coalescence devices that can coalesce droplets with minimum radius smaller than 0.01 micron, thereby lowering the equilibrium supersaturation, enabling water droplets to grow faster, be more stable and easier to be removed compared to when coalescence is absent. The method dehumidifies the air so that the water droplets with captured aerosols are removed. Coalescence enables droplets to grow under a lower ambient supersaturation level, thus saving a considerable amount of energy.

An impact test apparatus can be used to determine particle interfacial energies with varying relative air humidity. It was observed that capillary condensation increased the adhesive forces of hydrophilic materials. A systems humidity separation window was identified and the differences in interfacial energy for a hydrophilic surface and for a hydrophobic surface can be exploited in order to achieve the separation of particles. Separation and concentration of particles, particularly particles within a mineral ore body, can be obtained.