Agitating – Jet or spray impinging free-falling stream
Reexamination Certificate
1998-11-05
2001-07-03
Soohoo, Tony G. (Department: 1723)
Agitating
Jet or spray impinging free-falling stream
C366S157200, C366S167100, C366S165100
Reexamination Certificate
active
06254267
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a method and an apparatus for mixing dry powder into liquids, and more specifically to methods and an apparatus for metering, dissolving, wetting, feeding, and mixing solid chemicals in powder or granular form into either a batch or continuous stream of fluid.
BACKGROUND OF THE INVENTION
Many industries employ technologies requiring dry powders mixed into liquids. Some of these industries, such as wastewater treatment, are not intuitively apparent. Others, such as brine production, are more apparent. These technologies utilize a wide variety of dry powders such as salt and lime, for mixing into fluids, especially water.
Wastewater Treatment
Wastewater treatment frequently mixes dry powders into water. In the treating of water for removal of contaminants, various chemicals perform selected functions in the treating process. The chemicals can be liquids or solids in granular or powder form. Some solids are dissolved into and used as liquids in the treating process. Other chemicals may perform their treating functions as solids.
Many separation processes used in wastewater treatment employ coagulation and/or flocculation. Laymen have long used the terms “coagulation” and “flocculation” interchangeably in discussing solid-liquids separation processes. Colloid scientists, however, have adopted a more specific usage. “Coagulation” implies aggregation caused by compression of the electrical double layers surrounding colloidal particles. “Flocculation” is restricted to cases where polymer bridging or some similar mechanism operates. Coagulation and flocculation are essential in many solid-liquid separation processes, since many suspended particles are too small for gravitational settling alone to effectively remove the particles. Coagulants can be purchased in both the liquid and the solid phases. Polymers used as flocculating agents can also be obtained in the liquid and solids phases. In the liquid phase, those chemicals must be mixed and dispersed to react with the contaminants throughout the water. In powdered or granulated solid form, those chemicals must be dissolved first and then mixed with water in order to react with the contaminants.
Chemicals that remain powdered during the treating process may also be used in addition to coagulants and flocculants to remove contaminants from water. Bentonite clays and activated carbon powders exemplify such solid chemicals used to remove organic and dissolved metal contaminants from water. The powders must be wetted, fed into the water, and dispersed in order to reach the contaminants throughout the body of water to be treated. Once injected into the water, the powders may also have to be coagulated and flocculated so they can also be settled and filtered to remove them from the water.
Brine Production
Brine production frequently mixes dry powder into water. Dissolving salt (NaCl) in water creates brine. Brine solutions are used in various concentrations in the regeneration of ion exchange resins for water softening and other applications. Saturated brines are normally diluted to make other concentrations when needed for specific applications. Brine used in the regeneration of water softeners is generally produced on site by dissolving salt in water. There are several types of salt used for this purpose, including rock salt, evaporated salt, and solar salt. Rock salt is mined from underground salt deposits by mechanically excavating it and elevating it to the surface Evaporated Salt is produced from brine mined by injecting hot water into an underground salt formation underground. The dissolved salt, brine, is brought up to the surface where the water is evaporated leaving the salt in solid state. A third type of salt is retrieved from the bed of lakes into which water flowed in geological times where it was captured and water evaporated by solar action to produce Solar Salt.
Lime Mixing
Lime is yet another material commonly used as a dry powder for mixing into powders. Lime is used in the production of other chemicals, steel, non-ferrous metals, pulp and paper, sugar, cement and plaster, leather, rubber, glass, glue, paint, and other products. Commercial lime is produced in two basic forms including quicklime and hydrated lime, both in powder form. Large quantities of lime typically have to be prepared, in both large and small batches, for use in metering, dissolving, wetting, and mixing in fluids.
Drilling Fluids
One common end product of mixing dry powders into liquids is a drilling fluid. Sophisticated drilling fluids, often called “drilling mud,” are used to perform a variety of functions in oil well drilling operations. Millions of tons of dry powders are delivered to the drilling sites each year to be converted to flowable fluids with both soluble and insoluble substances. Water is widely used as the principal fluidizing medium in drilling fluids. Some chemicals are delivered to drilling sites premixed as fluids for emergencies or as specialty chemicals.
Barite has traditionally been the largest quantity of dry powder used by the industry. Barite typically is the only dry chemical delivered to the site in bulk. A method commonly used to transfer the bulk Barite drops the powder through the open air into a hopper. Virtually all other chemicals used in drilling fluids are packaged, transported, and stored in bags or sacks. As the chemicals are used, the sacks are cut open and the powders are poured out into open hoppers. Whether the chemicals are mixed on the drilling sites or at the warehouses, some of the same problems of handling dry powders exist.
SUMMARY OF THE INVENTION
The invention is a method and apparatus for mixing a powder into a liquid. In a first aspect, the invention includes an apparatus into which a powder can be fed for mixing into a liquid. The apparatus comprises a wetting housing defining a wetting chamber having a top part, a bottom part, a top port in the wetting chamber's top part, and a bottom port in the wetting chamber's bottom part; means for preventing powder from clumping by fluid force imparted from the wetting chamber's top part to keep the powder from accumulating before mixing; and a spray at the wetting chamber's bottom part to swirl the liquid and mix the powder in the liquid.
In a second aspect, the apparatus is a part of a system including a tank that, when filled, contains the liquid and includes a first port and a second port permitting fluid flow through the tank; a source of the liquid; and a controller controlling the operation of the wetting chamber and the tank.
In a third aspect, the invention is a method comprising feeding the powder into a chamber having a bottom part and a top part; swirling the liquid into the bottom part of the chamber; injecting a fluid into the top part of the chamber to prevent the powder from clumping; and extracting the mixed powder and liquid from the chamber.
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Howrey Simon Arnold & White , LLP
Hydrotreat, Inc.
Soohoo Tony G.
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