EP1701774A1

EP1701774A1 - An improved self-cleaning water processing apparatus

Info

Publication number: EP1701774A1
Application number: EP04812500A
Authority: EP
Inventors: Douglas M. Thom; Gary W. Lum; Joseph A. Urban
Original assignee: Sylvan Source Inc
Current assignee: Sylvan Source Inc
Priority date: 2003-12-02
Filing date: 2004-12-01
Publication date: 2006-09-20
Also published as: CA2553651A1; EP1701774A4; JP2007513752A; WO2005056153A1

Abstract

An improved self-cleaning water purification system based on distillation. The unit comprises a boiler chamber (2), a degasser (4), and a cyclone demister (3). The improvements include high-volume fabrication and manufacturing, simple disassembly for inspection, repair and service, and rugged construction in order to withstand vibration and mechanical shock.

Description

PCT Patent Application

Title: An Improved Self-Cleaning Water Processing Apparatus

Cross Reference to Related Applications

This Application claims the benefit of the filing of US Provisional Patent Application Ser. No 60/526,580, entitled "An Improved Self-cleaning Water Processing Apparatus," filed on December 2, 2003, and the specification thereof is incorporated herein by reference.

Background of the Invention

Field of nvention:

This invention pertains to the distillation of water and other liquids and, more specifically, to a distillation system and method utilizing initial degassing of the liquid, evaporation by boiling, selective separation of steam and vapor, and product condensation.

Relevance of the Invention:

Water purification technology is rapidly becoming an essential aspect of modern life as conventional water resources become increasingly scarce; as municipal distribution systems for potable water deteriorate with age; as increased water usage depletes wells and reservoirs, causing saline water contamination; and as further contamination occurs in conventional resources from intensive agriculture, from gasoline additives, and even from heavy toxic metals, leading to increasing and objectionable levels of germs and bacteria, salts, MTBE, chlorates and perchlorates, arsenic, mercury, and chemicals used to disinfect potable water, such as chlorinated compounds.

Conventional technologies, such as reverse osmosis (RO), filtration, and chemical treatment rarely are able to handle the diverse range of water contaminants, and even though they are commercially available, they often require multiple treatment stages or combination of various technologies to achieve acceptable water quality. Less conventional technologies, such as ultraviolet (UV) light irradiation or ozone treatment can be effective against viruses and bacteria, but seldom remove other contaminants, such as dissolved gases, many salts, hydrocarbons, and insoluble solids. And most distillation technologies, which are generally superior at removing multiple contaminants, and unless they include selective steam separation systems, are still unable to handle all types of contaminants.

Accordingly, sophisticated distillation systems that are continuous, self-cleaning, and recover a major fraction of the input water appear as the best long-term option to resolve increasing water contamination problems and water scarcity. However, to be effective, such distillation systems must remove solids, dissolved gases, dissolved salts, bacteria and viruses, as well as odors and hydrocarbons, which is the subject of this invention.

References Cited U.S. Patent Documents

Patent No Date Inventors Assiαnee

6,689,251 2/10/04 William H. Zebuhr Ovation Products

6,423,187 7/23/02 William H. Zebuhr Ovation Products

6,663,770 12/16/03 Stephan B. Sears

5,968,321 10/19/99 Stephan B. Sears Ridgewood Water Pure

6,436,242 8/20/02 Sanchez, et al Sanchez and Joaqurn

6,506,284 1/14/03 Tetsuo Miyasaka Vacuum dist

6,428,656 8/6/02 Bleth, et al PS1-ETS

6,406,597 6/18/02 Chi-Hsiang Wang

6,365,005 4/2/02 James W. Schleiffarth

6,294,054 9/25/01 Douglas E. Sutter

6,113,744 9/5/00 James Munro

5,729,987 3/24/98 Joel V. Miller

5,484,510 1/16/96 Hartman, et al Dew Enterprises

5,587,055 12/24/96 Hartman, et al

5,536,375 7/16/96 Jonathan C. Vogelman Emerson Electric

5,522,970 6/4/96 Shimizu, et al Japan Gore-Tex

5,435,891 7/25/95 William H. Snitchler

5,232,085 8/3/93 Hayashi, et al Hitachi, Ltd.

4,938,868 7/3/90 Thomas R. Nelson

Description of Prior Art

Previous attempts at removing all contaminants from water distillation systems are known from U.S. Patents 6,689,251 ; 6,423,187; 6,663,770; 5,968,321 ; 6,506,284: 6,428,656; 6,406,597; 6,294,054; 6, 13,744; 5,729,987; 5,484,510; 5,587,055; 5,536,375; 5,522,970; 5,435,891; 5,232,085; and 4,938,868. U.S. Patent 6,689,251 describes a distiller with a heat exchanger that allows for the periodic bleeding of boiler water as the impurity concentration in that water increases. However, there is no provision for separating the steam produced in the boiler into clean and impure fractions. Another patent from the same inventor, U.S. Patent 6,423,187 describes a distiller system that operates on the principle of thin-film evaporation by means of capillary action wicks. U.S. Patent 6,663,770 describes a self-cleaning distillation system comprising a degasser, boiler, and steam separation system. However, that invention includes a float valve to control the water level in the boiler, with the attendant abrasion and mechanical stability problems associated with such systems at boiling temperatures. It also describes a shaft that operates a mechanical wiper for cleaning the boiler, which introduces potential leak and maintenance problems. U.S. Patent 5,968,321 describes a similar distillation system that relies on a heat exchanger and a compressor to recover part of the heat of condensation, and controls the level of water in the boiler by means of a side glass tube connected to a photo-sensing device. In addition, there is a number of U.S. Patents, such as 6,436,242; 6,506,284; 6,294,054; that utilize vacuum distillation as a means of reducing the energy requirements due to evaporation. While vacuum distillation effectively allows boiling at less that 100°C, it is prone to leaks, and such leaks become increasingly likely the larger the distillation unit becomes. Another common deficiency of vacuum distillation systems is that they usually require a vapor compression stage, and compressors suffer from high maintenance costs and, unless they are especially sealed, can introduce lubricant contamination into the water product. Thus, vapor compression distillers, such as U.S. Patents 6,365,005; also suffer from similar reliability and contamination problems. U.S. Patent 6,428,656 describes a screen above the boiling level of the boiler as a means of capturing the salt-containing mist droplet. Metallic or hydrophilic screens can capture liquid droplets, but the efficiency of capture is a function of droplet size, and unless the screen apertures are microscopic (which in turn cause a significant pressure drop across the screen), they can allow passage of small mist droplets.

U.S. Patent 6,406,597 describes a distiller with a degasser and a demister. The demister consists of a flexible tube. Collecting impure mist droplets in a tube is generally a stochastic process that is seldom 100% efficient, and depending of the chemical composition of the polymer tube, impurities can leach into the steam that eventually becomes product water. U.S. Patent 6,113,744 describes a degasser where raw water is introduced between the top and the bottom of a tubular member, with steam exit at the top of the unit and degassed water at the bottom. Such configuration achieves degassing only of the most volatile components in the water stream and is less efficient that the present invention, particularly when volatile components like MTBE and chlorine are both present in the raw water.

U.S. Patent 5,729,987 describes a distillation apparatus for use with salt water and is based on an array of steam separator ducts that prevent mixing of salt water with desalinized water, and using an ammonia refrigerant for heat exchange.

U.S. Patents 5,484,510 and 5,587,055 describe a distillation system that separates clean from impure steam by means of a pump actuated by an electric conductivity probe. However, conductivity measurements in the gas phase are effective only if the steam is homogeneous, which is not the case when mist containing micro-droplets of liquid are present. U.S. Patent 5,536,375 describes a vacuum distillation system that utilizes a mechanical baffle to separate mist droplets from steam. However, in addition to the aforementioned problems of vacuum distillation, a baffle is only effective at capturing droplets above a certain size; smaller droplets have significantly lower inertia and will continue to be entrained by the flow of steam. U.S. Patent 5,522,970 describes a distillation system based on a polytetrafluoroethylene tube that is permeable to water steam but impermeable to saline water.

U.S. Patent 5,435,891 describes a distillation system that eliminates gases fe>y heating, but there is no provision for separating clean from impure steam.

U.S. Patent 5,232,085 describes a distillation system that includes a degasser, a high-pressure boiling chamber, and a hydrophobic membrane to separate the steam from mist droplets. However, in addition to the aforementioned problems regarding high-pressure systems, a membrane separator is effective only if the mist droplets are within a certain size; smaller droplets can be carried through by the steam flow because of their low inertia.

U.S. Patent 4,938,868 describes a vacuum distillation system that utilizes a circular mist collector to separate mist droplets from clean steam. However, in addition to the aforementioned problems associated with vacuum distillation, the patent recognizes that only large mist particles can be collected.

The objective of the present invention is to provide a continuous, fully automated water distillation system that removes gases, solids, salts, hydrocarbons, and micro-organisms from water.

Summary of the Invention

An improved, self-cleaning water processing apparatus comprises three sequential functions that eliminate multiple contaminants from drinking water. First, dissolved gases, such as odors and most hydrocarbons, are eliminated by means of a degasser. Next, a special design boiler produces steam that may carry micro-particles of solids or salt-containing mist. The mixture of clean arrd contaminated steam is then separated into pure and impure steam by means of a cyclone demister. The clean steam fraction is finally collected in a condenser which feeds a pure water product tank.

Brief Description of the Drawings

FIGURE 1 is top view of the boiler chamber 2, the degasser unit 4, and the cyclone demister 3.

FIGURE 2 is a side view of the distillation core, showing the degasser 4, the boiler chamber 2, and the cyclone demister 3.

FIGURE 3 is a detailed view of the cyclone demister 3, illustrating a preferred configuration of various elements, such as an incoming steam tube 11, a metallic steam guide 10 that directs the steam to rotate in a circular pattern, a mist collector tube 6 that directs impure steam and mist into a waste drain, and a clean steam collector tube 5 that carries the clean steam into a condenser un it.

FIGURE 4 is a detailed drawing of the degasser unit 4 as mounted above the boiler chamber 2 on the boiler top 1. It illustrates a preferred configuration for the incoming feed water tube 12, the positron of a coiled heat exchanger 8 inside the boiler chamber 2, the hot water tube 13 that feeds the top of the degasser unit 4, the mixing media 14 inside the degasser unit 4, the screen 15 that supports the mixing media 14, and tube 16 that carries contaminated steam and mist to a waste drain. Detailed Description

As illustrated in the drawings, the distillation system comprises a boiler, a degassing unit, a demister for steam separation and a product condenser. FIG. 1 and FIG. 2 are top and side views of the apparatus constructed in accordance with the invention. The boiler top (1) is the primary structural element of the apparatus and mounted to it are the boiling chamber (2), the cyclone demister (3), and the degasser (4). O-rrngs (not shown) form the seal between the borlrng chamber and boiler top; and between the cyclone demister and boiler top. All materials in the apparatus are selected to minimize corrosion of the apparatus or contamination of water being processed, such as titanium or stainless steel.

- Design has been improved to enable high-volume component fabrication and high-volume manufacturing assembly processes, substantially reducing manufacturing costs. Steel drawing of the boiling chamber eliminates gaskets or seals in the boiler, thereby minimizing maintenance costs, while making the body of the boiler easier and more economical to manufacture. In addition, making the body of the boiler by steel drawing and forming makes the unit more durable, thus extending the useful life of the core assembly.

- Design has been improved to enable speedy disassembly for the purposes of inspection, service cleaning, and repair or replacement of components. The boiler chamber 2 is attached to the boiler top 1 by a series of peripheral bolts and an O-ring that is placed outside the line of bolts, so as effect a compression seal, thus minimizing any contact between the steam and the Q-ring.

- Design has been improved to withstand the mechanical shock and vibration performance seen in transportation, installation, and continuous operation. The ability to withstand these stresses significantly improves the reliability of the apparatus.

Cyclone Demister Component:

- The design of the cyclone demister 3 improves prior art by combining and integrating the cyclone chamber, steam nozzle, and demister seal gland into a single component which may be fabricated by molding, casting, or stamping a variety of corrosion resistant materials. In a preferred embodiment, the body of the cyclone demister is made from either titanium or stainless steel, although other temperature and corrosion resistant materials may also be used.

- The attachment of the demister 3 to the boiler top 1 is accomplished by threaded fasteners and by a compression seal made with an o-ring. - As shown in Figure 3, the cyclone demister is basically a modified cyclone. Steam from the boiler chamber enters the cyclone demister through tube 11. Upon entering the cyclone chamber, steam from the boiler encounters a metal guide 10 that forces the steam into a circular motion. The circular motion of steam in the cyclone causes mist particles, which are heavier than dry or clean steam to concentrate on the periphery of the cyclone chamber due to centrifugal forces, while clean steam, being lighter, follows a circular motion closer to the center of the cyclone chamber. As should be apparent to those versed in the art, the cyclone demister has no moving parts, and effects a selective separation of clean steam from impure mist particles purely as a result of differential centrifugal forces. During this circular motion, the concentrated mist stream, also called "blow-down," encounters exit tube 6 and leaves the cyclone demister as waste steam. This waste steam subsequently joins the gray water stream and goes to a drain. Dry or clean steam exits from the center top of the cyclone demister through tube 5 and goes to a condenser uni

Boiling Chamber Component:

The boiling chamber 2 design makes improvement over prior art by employing high volume metal forming technology to minimize the number of seams, seals, and piece parts which significantly improves manufacturing cost and reliability of the device.

- The single and only boiling chamber seal, except for drains, is made above the operating water line which further reduces the opportunity for leakage during normal operation.

- The heating element 10 which is permanently and intimately attached provides heat in a confined area of the boiling chamber bottom. The nature of boiling water causes (sediment) or scale to form on or near surfaces where the boiling process takes place. Glass or ceramic balls 7 within the boiler are agitated by the boiling water and prevent the scale from being deposited on the surface of the boiling chamber keeping the particles suspended in the water during normal operation.

- At the end of an operational cycle of the unit, a sediment drain 9 opens automatically purging the boiling chamber of nearly all the water and suspended scale. This process significantly reduces the long-term build up of scale which improves the heating efficiency of the boiler and reduces the need for boiler cleaning.

- The water level and the steam pressure in the boiling chamber are automatically regulated by means of a differential pressure switch that turns the inlet water valve off when the level of water in the boiler is full. - As shown in Figure 4, incoming feed water enters the boiler chamber through tube 12 and is preheated inside the boiling chamber within a heat exchanger 8 which is suspended from the boiler top 1. The feed water reaches temperature equilibrium with the boiling chamber and exits through tube 13, which carries the hot water into the top of the degasser 4. This preheating process is key to bring feed water temperatures near the boiling point before it enters the degasser. As is known to those familiar with the art, volatile gases and organic compounds with a low vapor pressure lose the ability to remain in solution at temperatures close to the boiling point of water, and evolve as gases.

Degasser Component:

The Degasser 4 consists of a vertical tube with preheated water entering the top through tube 13 and steam from the boiler chamber 2 entering the bottom and exiting at the top through tube 16. The vertical degasser tube 4 can contain a variety of materials 14 which cause a mixing of the water and steam stripping off unwanted gases in the water as it moves slowly down the degasser by gravitational force. The materials that can be used for this mixing include glass balls, ceramic balls, screen discs, spiral screen, or metal chards. A metal screen 15 that is resistant to corrosion is placed between the degasser tube 4 and the boiler top 1, and prevents the mixing media 14, which in a preferred embodiment consist of glass spheres, from falling into the boiling chamber.

An important aspect of the present invention concerns the size of the glass spheres, which must have sufficient surface area to provide for effective stripping of volatile components in the short time it takes for the incoming feed water to traverse the length of the degasser tube. Horizontal configurations of degassers in the prior art normally are not effective for this reason and are, thus, unable to completely strip volatile substances from contaminated water. Ultrasonic atomizatron of water may also be used to enhance the steam and water mixing.

Claims

What is claimed is a fully automated, continuous, and self-cleaning water processing system that provides: 1. Full elimination of odors and dissolved gases from drinking water by means of a continuously operating water degasser unit. 2. Effective evaporation of contaminated water in a boiler chamber that maintains scale in suspension and that periodically drains the boiler to prevent excessive accumulation of salts, solids, and dead microorganisms. 3. A method for effective separation of clean and impure steam by means of a cyclone demister that recovers a substantial portion of the steam as a pure fraction. 4. The integration of embodiments 1 , 2, and 3 above into a fully automated system that removes solids, gases, salts, hydrocarbons, and microorganisms from drinking water. 5. A fully integrated distillation system that operates at near atmospheric pressure and delivers a substantial fraction of the inlet water as pure, uncontaminated water, free of solids, gases, salts, micro-organisms, and hydrocarbons.