Patent Application
20140251383
The present invention relates to the flow of fluid through tubes, including the treatment of the interior of tubes.
Many types of equipment employ tubes or tube bundles. It is often necessary to introduce a fluid into the tubes and to remove fluid from the tubes, for a variety of purposes. For example, it is often necessary to treat the interior of these tubes. In many instances, foreign matter builds up on the inner surfaces of the tubes, which degrades performance of the equipment, and must be cleaned to remove the foreign matter.
For example, heat exchangers and other types of condensers, particularly those used in the production of electrical power, develop scale on the interior surfaces of the condenser tubes. This scale impedes heat transfer between the interior of the tubes and the fluid (for example, water or steam) surrounding the tubes, and reduces the efficiency of the power generator. The term “fluid” is used herein to include both gases and liquids. In a typical condenser, for example, the tube bundle is contained with an enclosed condenser box, which affords limited access to the tube bundle. Cleaning the interior walls of the tubes is a challenge, given the difficult access to the interior of the tubes, and the need to accomplish the cleaning as quickly as possible to minimize the down time of the generator.
The current technology employed to clean the interior surfaces of tubes falls broadly into one of three categories: mechanical tube cleaning, hydro-blasting, and chemical cleaning. Each technique is very well known to those in the industry.
Mechanical tube cleaning is generally the fastest method for cleaning deposits from the interior surfaces of tubes. There are numerous types of mechanical tube cleaners, the design of which are based on the type of deposit the device will be removing. Mechanical tube cleaning devices can be used to remove very soft to very hard deposits. Examples of hard deposits are calcium, mostly calcium carbonate, manganese, and silica-based deposits. Mechanical tube cleaning involves propelling a tube cleaner, also known as a scraper, through the tube using a fluid under pressure. As water propels the tube cleaner, deposit is removed by the contact points of the device and then remaining deposit is subsequently flushed out by the water. Mechanical cleaning is generally the most common method because it is fast, cost effective, and the more durable tube cleaning devices are able to remove most deposits. The major disadvantage of this method is that some deposits are so difficult that mechanical cleaning is either not effective or less cost effective than other techniques. For example, a very thick calcium carbonate deposit would be very hard to remove with a mechanical tube cleaner. With such a deposit, it is likely necessary to make multiple passes through the tube with different sized scrapers. The process would begin with a smaller diameter scraper, with subsequent passes being made by scrapers with increasingly larger diameters to progressively scrape layers of scale from the inner tube surface. Depending on the size of the deposit, the mechanical process could be impractical in this case.
Hydro-blasting uses extremely high pressured water to remove deposit from the inner walls of tubes. An operator uses a lance that shoots out high pressured water and manually feeds this lance down each tube. This method can be seen as a substitute to mechanical tube cleaning, but has some significant disadvantages. Generally hydro-blasting takes more time than mechanical tube cleaning and the high pressured water can make this method extremely unsafe for the lance operator.
Chemical cleaning is preferable on small tube bundles (fewer than about 3,000 tubes of average length, typically between 20 to 50 feet in length), or when larger tube bundles have very serious deposits. Broadly, chemical cleaning involves flushing chemicals through the tubes. The chemical comes into contact with scale, and dissolves it. Typically, the entire condenser tube bundle is filled with the chemical. This system uses a re-circulating pump system that includes an inlet hose that forces the chemical from a reservoir into the bundle, and an outlet hose that evacuates the chemical and returns it to the reservoir. The chemical is re-circulated from the reservoir by the pump until the cleaning operation has been completed. New chemical is supplied to the bundle from a separate reservoir either automatically by a pump or manually. Some systems include a pH gauge that monitors the changing pH of the chemical during the cleaning operation. As the chemical dissolves the deposit, the pH of the chemical changes, typically increasing. When the pH of the chemical rises to a predetermined level, another pump begins supplying chemical from a separate reservoir. Also typically, the predetermined pH level of the system can be set within a range. While this system is effective in removing deposits from the tubes, it is expensive primarily due to the cost of the chemical required to completely fill the tube bundle.
The present invention provides a device for providing fluid access to the interior of a tube, and a system, method and device for circulating fluid through tubes. The system can be used for treating the interior surface of one or more tubes, and utilizes a sealing device of the type provided by the present invention that seals the ends of the tube while permitting the fluid to enter and exit the tube. The system can be used to force a chemical liquid through the tube to remove scale from the interior surfaces of the tube. The system can be used to treat individual tubes or multiple tubes. Entire sections of a tube bundle can be treated. The system provided by the present invention is particularly useful for cleaning scale from the interior of tubes, like those in the tube bundle of a condenser or heat exchanger, using a chemical cleaning fluid. The sealing device can be used to introduce fluid into a tube, and allow for removal of the fluid from the interior of a tube for any purpose, including cleaning or descaling the interior surface walls of the tube.
The sealing device provided by the present invention includes an inlet for receiving fluid, an outlet, a fluid passage adapted to permit flow of the fluid between the inlet and the outlet, and a seal adapted to prevent flow of the fluid between the sealing device and the interior of the tube. A first sealing device may be mounted within a first end of a tube and a second sealing device may be mounted within a second end of the tube to permit the fluid to pass through the tube. In a preferred embodiment of the invention, the sealing device provides a seal between the device and the tube wall utilizing a sealing material that can be expanded under pressure to force the sealing material against the interior surface of the tube to provide a seal against fluid leaking from the tube, and against foreign matter entering the tube from the exterior of the tube. Preferably, the sealing material is expanded against the inner surface of the tube using a nut and bolt assembly provided with the sealing device that compresses the sealing material. Also preferably, the sealing material is at least one sealing sleeve. In most applications, two sealing sleeves are preferred.
A treatment system provided by the present invention is used to treat the interior surfaces of at least one tube with a treatment fluid. The treatment system can be used to remove scale from the inner surfaces of tubes by forcing a chemical through the tube.
The system includes a supply of treatment fluid, a feed that provides treatment fluid from the supply to the tube, a return that recirculates treatment fluid to the supply after it has passed through the tube, and a sealing device of the type provided by the present invention. The sealing device establishes fluid communication between the supply and the interior of the tube. The device includes an inlet and an outlet, a fluid passage adapted to permit flow of the treatment fluid between the inlet and the outlet, and a seal adapted to prevent flow of the fluid between the device and the interior of the tube, and to prevent foreign matter from entering the tube from the exterior of the tube.
The treatment system can be used to isolate a section comprising multiple tubes to clean more than one tube of the tube bundle while bypassing sections that do not need to be cleaned. In this instance, a sealing device is mounted in the inlet and outlet ends of the tubes being cleaned, and manifolds are provided that are in fluid communication with the inlets and outlets of the tubes being cleaned. As is known in the art, the manifolds distribute the treatment fluid to and from the tubes being treated.
The system provided by the present invention can be configured in a number of ways to treat a section comprising multiple tubes. For example, a section of six tubes can be treated by configuring the system in a “multiple loop” configuration. In a multiple loop configuration, pairs of tubes are coupled to allow treatment fluid to enter a first tube of the pair, exit the first tube and enter the second tube. The fluid is returned to the system upon exiting the second tube. In this configuration, the system defines three independent flow loops. Alternately, a system can be provided that employs a “continuous loop” configuration. In a continuous loop configuration, the tubes are coupled to form a single flow path for the treatment fluid. The outlets and inlets of the tubes are coupled to form the flow path. With the “multiple loop” and the “continuous loop” configurations, the pump and fluid treatment reservoir could be completely contained within the condenser box. In that case, all hoses that are used to connect the tubes with the pumping system are also located within the condenser box.
The system also can employ an “individual loop” configuration. In an individual loop configuration, each tube forms an independent flow path to and from the system supply. In an individual loop configuration, the inlet of each tube receives treatment fluid from the supply through a single inlet, and returns fluid to the supply through a single outlet. This configuration includes a hose that runs from the pumping system to an inlet manifold that distributes the treatment fluid to the inlet of each tube, and an outlet manifold on the outlet side of the of the tube bundle that collects the treatment fluid after it passes through and exits the tubes, and returns it to the pumping system.
Other configurations, including combinations of these configurations, can be employed.
The method provided by the present invention includes the steps of providing a supply of treatment fluid, feeding treatment fluid from the supply to the tube, returning treatment fluid to the supply after it has passed through the tube, and providing fluid access to the interior of the tubes using a device that includes an inlet and an outlet, a fluid passage adapted to permit flow of the treatment fluid between the inlet and outlet, and a seal adapted to prevent flow of the fluid between said device and the exterior of the tube.
The following detailed description of the preferred embodiments may be understood better if reference is made to the appended drawing, in which:
The preferred embodiments of the present invention shown in the drawing are particularly useful for chemically cleaning scale from the inner surfaces of condenser and heat exchanger tubes. However, the present invention can be used to deliver any type of fluid to the interior of tubes for any purpose. Further, the present invention, including the embodiments shown in the drawing, can be used to treat tubes singly or together in a section of a tube bundle.
When used as a chemical cleaning system to, for example, clean the interior of condenser tubes, the system can employ any type of chemical cleaning fluid currently used to clean scale and deposits from the inner surfaces of condenser tubes. Chemical cleaning of condenser tubing is a well-known and established industry, and the chemicals that can be used in the cleaning process are very well known. For example, the chemical sold for this purpose by Apex Engineering Products Corporation, of Aurora, Ill., (“Apex”) under the trademark RYDLYME® works well and can be used with the present invention. Similarly, the manifolds, fluid supply reservoirs, pH sensors, control circuits and pumps used in current chemical cleaning systems are well known. Examples are the pumping system components sold by Apex and Goodway Technologies Corporation of Stamford, Conn. Consequently, those components of the system will not be described in detail herein.
System 10 includes a reservoir 12 that contains a chemical, of any known type, that removes scale from condenser tubes. A feed 14, consisting of an inlet line of any known desirable type, is provided to deliver chemical fluid from reservoir 12 to tube bundle 16.
In use, pump 28 forces cleaning fluid from reservoir 12 into feed 14 and into tube 18a via a sealing plug 20. As the cleaning fluid flows through tube 18a, it reacts with scale on the inner surface of tube 18a, dissolving at least some of it. The fluid exits tube 18a through another sealing plug 20, passes through U-connector 22, and enters tube 18b through a third sealing plug 20. As with tube 18a, the cleaning fluid reacts with scale on the inner surface of tube 18b as it flows through it, dissolving some of the scale as it does so. The cleaning fluid exits tube 18b through a fourth sealing plug 20, enters return 24 and is pumped back into reservoir 12, from which it is recirculated until its pH, as measured by sensor 26, has risen to a predetermined level. At this point, new cleaning fluid is introduced into system 10 from reservoir 13, either manually or automatically through pumping system 29.
For example,
System 200 includes a pump 228 that pumps fluid from a reservoir 224 through system 200. A pair of hoses 230 carries fluid pumped by pump 228. Hoses 230 are mounted to a manifold 232. Manifold 232 defines outlets 234, each of which is mounted to an inlet hose 236. Each hose 236 is mounted to an endpiece 226. Ball valves 223 are mounted in known fashion within each manifold inlet 225 and manifold main inlet 227 to prevent unintended reverse flow. Consequently, pump 228 pumps fluid into hoses 230, through manifold 232, through hoses 236 and endpieces 226, and through plugs 100 into the interior of tubes 224.
A U-shaped connecting hose 238 is mounted to the endpiece 226 mounted to the outlet 222 of an inlet pipe 224a of each loop 212, 214 and 216 and the endpiece 226 mounted to the inlet 220 of the outlet tube 224b of the loop. As a result, fluid pumped through the inlet tube 224a of each loop 212, 214 and 216 exits an outlet 222, through connecting hose 238 and into outlet tube 224b. The fluid then flows through outlet tube 224b, plug 100, endpiece 226, hose 236, manifold 232, hose 230 and back to reservoir 224 and re-circulated through pump 228.
Similarly,
Referring to
Plug 100 includes a threaded core 102 made from a suitable plastic or metal material, such as plastic: Delrin or acetal 570 or metal: stainless steel. Core 102 defines a flange 104 at one end, and a threaded section 106 at the other end. At least one cylindrical sealing sleeve 108 is provided, which defines a central bore 110, which is sized to be received along central section 112 of core 102. At least one sleeve 108 is mounted on section 112 of core 102. If more than one sleeve 108 is used, a plastic washer 113 is mounted between each pair of sleeves 108. Where, as with the embodiment shown in the drawing, a pair of sleeves 108 is employed, a single washer 113 is mounted between sleeves 108. Regardless of the number of sleeves 108 employed, a washer 114 is mounted on core 102 adjacent the end of the outermost sleeve 108. Washer 113 will have a smaller diameter than 114 to enable the diameter of washer 113 to more closely match the diameter of sleeves 108. A nut 116 is threaded onto the threaded end 106 of core 102, and bears against washer 114. The diameter of washer 114 is chosen to be larger than the inner diameter of the tubes in which plug 100 is mounted to facilitate placement of plug 100 in a consistent location with respect to the tubes. That is, washer 114 acts like a “stop” that prevents inadvertent placement of plug 100 to far within the tube. Washers 113 and 114 function as the bearing surfaces against which the force generated by nut 116 is exerted against the ends of sleeves 108, which in turn operates to expand sleeves 108 and force them into sealing engagement with the interior of tube 118 (see, particularly,
Core 102 defines a passage 120 through which fluid can pass through core 102. Endpiece 226 includes a threaded section 600 which is threaded onto threaded section 106 of plug 100 to mount endpiece 226 to plug 100. A hose or line 120 can then be mounted to endpiece 226 using a conventional coupling 21.
To mount a plug 100 within a tube 118, a sleeve 108 is mounted onto center section 112 of plug 100. The length of section 112 and the number of sleeves 108 can vary. The length of section 112 will typically be between three and four inches and plug 100 will typically have one washer 113 separating two flexible bushings or sleeves 108 and an additional washer 114 separating sleeves 108 and nut 116, which will typically provide an effective seal. These configurations can be changed to alter the nature of the seal as is well known in the art. Generally, the effectiveness of the seal between the plug 100 and a tube increases as the number of washers 113 increases and the length of the bushings 108 decreases. However, as will be appreciated by those in the art, the increased number of washers 113 will begin to compromise the effectiveness of the seal. A plug with two sealing sleeves 108 separated by a washer 113 will provide an effective seal in most situations. If it is found that the seal is not adequate, those in the art will appreciate how to modify the number and length of the sleeves 108 to improve the seal. For example, if a tube is severely eroded and, consequently, achieving a seal is difficult, the plug 100 may need to be made longer or more washers 113 will need to be added, which would mean more, and shorter, sleeves 108 would be provided on the plug 100.
Flange 104 is inserted into a tube 118 that is to be cleaned, and a nut 116 is threaded onto threaded end 106 of plug 100. As nut 116 is tightened, sleeves 108 expand radially to provide a seal between plug 100 and the interior of tube 118. In this regard, the washers 114 provide bearing surfaces for the pressure exerted on sleeves 108 by nut 116, and ensure more uniform expansion of sleeves 108. When plugs 100 are fully mounted to each end of tube 118, fluid is free to pass into and out of tube 118.
Although the invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit or scope of the invention. For example, it is to be understood that changes may be made in details, including in matters of shape, size, and arrangement of parts in accordance with the appended claims. The foregoing description of embodiments of the invention have been presented only for purposes of illustration and description. These embodiments were chosen and described to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular uses contemplated. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed descriptions.
