This application is based upon Chinese Patent Application No. 200910249925.9 filed Dec. 4, 2009 and Chinese Patent Application No. 200920293550.1 filed Dec. 4, 2009.
1. Technical Field
This invention relates to the technical field of large diameter fiber-reinforced plastic (FRP) flues for chimneys and, more particularly, to a mold and method for manufacturing large diameter FRP cylinders.
2. Background Technologies
The implementations of environmental conservation policies in the US and western countries, particularly for flue gas desulfurization, initiated the sulfur dioxide removal in the late 1970s and early 1980s by using desulfurization equipment and the techniques. China (CPR) has since 2005 required and encouraged national environmental policies for chimneys in operations and newly constructed ones nationwide to be fit or retrofit for desulfurization so as to reduce the emission of sulfur dioxide.
Most conventional desulfurization techniques are in the method of wet scrubbing, meaning that flue gas comes out of boiler, through the scrubber and a shower of alkaline solutions, then enters breeching and the chimney to be discharged into atmosphere. However, about 5% of the sulfur dioxide still remains in the flue gas being discharged. Since the temperature of the flue gas stays around 120° F., sulfur dioxide mixing with oxygen and water turns into diluted sulfuric acid. Sulfuric acid causes acidic corrosions to the concrete and steel ducts and chimneys. Over a period of time, the corrosion will damage the concrete and steel chimneys partially or in a large scale or even collapse them.
The work conditions of the flue gas in chimneys before desulfurization go as high 266° F. to 302° F. in temperature. While scrubbers are in operation, the temperature of the wet flue gas goes down to about 120° F. When the generation units start up, flue gas will be super heated to as high as about 356° F. in a short period of time.
At the time of massive promotions of the desulfurization, the protections of the chimney structures are facing extraordinary serious challenges; no matter what anti-corrosion materials or techniques used, foreign or domestic, almost 90% or more chimneys will leak within a year. Consequently acids penetrate into the substrates of steel, seriously damage the structure of the chimney and put safety on risks. The potential losses in China along can be dozens of billions RMB (billions of US dollars).
Until today, the anti-corrosion liners inside chimney are categorized as: coating, mortar, borosilicate and foaming block lining, tile, alloy or titanium, and fiber-reinforced plastic (FRP) laminate lining.
Coatings crack easily, delaminate with limited thickness and mortars performs poorly on permeation and often disband and crack. Borosilicate and foam blocks need extended time for constructions. Tens of thousands grouting seams will be generally damaged from several flawed seams, which is co-related and interactive. Tile type of lining is the same as well due to the numerous seams. Titanium alloys are expensive and welding seams are subject to damages. Inevitable leaking also occurs. FRP flues on the other hand are more and more applied due to its temperature resistance, corrosion resistance, and reliable performance.
The main reason of the above mentioned anti-corrosion material failures in the chimney is because the materials are in contact with acid proof brick liner or concrete. Once damaged, acidic solutions penetrate into the brick liner and concrete may lead to structural damages.
In order to avoid chimney structural damages, flues inside the chimney shells or supporting structures are required. Flues are categorized into steel flues, brick/concrete flues, and fiber-reinforced plastic (FRP) flues. While steel and brick flues are easily damaged, FRP flues perform well.
However, at the time of using FRP or composites flues, large diameter FRP flues with diameters bigger than 10 feet or 12 feet, have to be manufactured with vertical filament winding apparatus established near the project site, in order to avoid high costs in trucking the FRP flues from the shop to the chimney or because of difficulty of transportation.
Even if the large diameters flues are cylindrically and vertically wound and manufactured onsite, with the diameter from 10 feet to 12 feet, even 15 feet to 30 feet wide, onsite vertical windings could face difficulties, such as weather, temperature, wind etc. A large hole needs to be cut in the chimney or duct to carry the FRP cylinders for installations. In the meantime, hoisting FRP cylinders around the chimney demands high level hoisting equipment and operations.
The above mentioned problems still restrict the extensive applications of large diameter FRP flues. The major limitations are existing complications in manufacturing large diameter FRP flues, difficulties in transportations, complexity in constructions, elevated costs, and low acceptance by industrial customers.
The invention aims to provide a mold and a method in manufacturing large diameter fiber-reinforced plastic (FRP) cylinders, to be conveniently fabricated in shops in quantities, making it easier for trucking and installations, and resolve the prior technical problems and difficulties for large diameter FRP flues and cylinders in transportations, onsite winding and installations.
The invention takes the following technical proposals in order to accomplish the above mentioned goals.
One type of mold for large diameter FRP cylinder mold for fabrication, comprises a circumferential segment plate, longitudinally ends with two end flat plates, and center axes which stick out longitudinally from the middle of the end plates. Both sides of the circumferential segments are connected with inward flange flat plates at radial directions. The inward flange flat plates are also connected with the said end plates.
On the inner side of the segment plates is the back side plate which can be connected with inward flange plates and end plates and supporting frames that are installed at the inside of the segment plate and the back side plate.
A method in manufacturing large diameter FRP cylinders includes the following procedures:
The beneficial effects of the invention are: manufacturing the large diameter FRP cylinders in shops and in quantity, facilitating transportations and installations, resolving the technical problems and difficulties in transportations of large diameter FRP cylinders, and onsite filament winding, and installations. The invention also greatly reduces the costs of productions, enhances the applications of most effective FRP flue anti-corrosion technology, resolves a large number of industrial chimney problems demanding urgent solutions, and effectively facilitates the development of environmental industries.
A more detailed explanation of the invention is provided in the following detailed descriptions and appended claims taken in conjunction with the accompanying drawings.
The following is a detailed description and explanation of the preferred embodiments of the invention and best modes for practicing the invention.
The inside of said circumferential segment plate 1 is structured with back side plate 4, connected with end plates 3 and inward flange plates 2. Supporting beams 6 brace between the circumferential segment plate and the back side plate.
This invention completely resolves the problems in extensively manufacturing large diameter FRP cylinders (chimney flues or tanks) in shops, instead of vertically filament winding large diameter FRP cylinders on site.
Among the many outstanding characteristic of this invention in sectional FRP cylinder fabrications is at the time of the fabrications, it fabricates the integral longitudinal inward flanges to the cylinders. At the time of fabrication and at the directional turning areas from the cylinder to the inward radius, one or more layers of fiber mesh cloth could be laid manually in order to reinforce the internal strength of the between inward flanges and the cylindrical bodies.
With reference to the above mentioned mold, the method of fabricating large diameter cylinders includes the following procedures:
This invention allows utilizing existing or similar horizontal continuous winding equipment for FRP pipes, altering the computer controlling program for the continuous cylinder or FRP pipe winding continuous fiberglass filament and mesh cloth. This invention can also alter the nonstop showering process to stop the showering until winding one layer to the needed thickness of fiberglass filament or cloth, then allowing showering equipment to move longitudinally for showering. The mold can be revolved in a small angle manually or by electric. Showering equipment once more moves and showers longitudinally until all the fiber glass filament and cloth get wetted out to the requirements. The molded entire surface is then started with the continuous winding process under the computer control, until the FPR circumferential segment reaches the desired thickness.
By adopting the inward flange design and fabrications, winding glass fiber or fiberglass mesh cloth keeps the same overall take-up tensions even on the inward flange radial surfaces. This can be the key of the inward flange surface design. If outward flanges need to be fabricated, there has been no previous way in keeping the take-up tensions during the continuous glass fiber or fiberglass mesh cloth winding until now. The only conventional methods of making outward flanges are bonding and using fixed molds, like making the rest FRP outward flanges. Manually assembly can form outward flanges in extensive length and can be unacceptably slow, leaving the total quality assurance at risk.
Major characteristics of the invention are different from the adoption of whole circumferential mold in fabrications of FRP vessels and FRP products, particularly the fabrications of large diameter FRP cylinders, which are not suitable for trucking transportation, but only via setting up vertical FRP winding facilities on site.
Many large diameter cylindrical products are only used at the working conditions of lower internal pressures, such as gas only flues, or low pressured solution tanks. This invention can avoid expensive on-site vertical winding technologies.
The entire mold can be about 12.5 meters long and the circumferential cylinder sections can be about 12 meters long after fabrications and truing. The length could be shortened as required, by making relatively shorter FRP sectional cylinders on the existing molds.
The invention resolves the problems of effectively using FRP flues inside existing chimneys. How to hoist large diameter FRP flues into the existing concrete chimney shell is an extraordinary difficult problem. The existing conventional method can open up a large hole on the concrete chimney. The sectional and composite cylinders in the invention can be hoisted in from outside of the chimneys, through a relatively much smaller hole opened up on the existing structures and concrete chimneys. Thereafter, the cylinders can be assembled inside the chimneys, and further assembled into the whole FRP flues.
The invention also resolves the problem of fabrications of large diameter FRP cylinders in shops. There is no need to setup a plant near the FRP flue installation site or vertical winding equipment. It avoids the delay in productions due to the weather and waste of composite materials.
The invention further resolves the problems in long distance transportations of large diameter FRP cylinders avoiding the costly 4 meter in diameter as the upper limit for transporting the FPR cylinders and costly large diameter FRP cylinder transportations in general.
The invention enormously promotes the applications of large diameter FRP cylinders in industries. By using superior composite resin materials with temperature resistance and chemical resistance, it can resolve numerous prior problems and difficulties.
The invention is not limited in circumferential sections, but could be sections and inward flange jointed in the shape of an arc, irregular shape but close to circles, rectangle or other shapes.
Although embodiments of the invention have been shown and described, it is to be understood that various modifications, substitutions, and rearrangements of parts, components, and/or process (method) steps, as well as other uses, shapes, construction, and design of the a mold and method for manufacturing large diameter FRP cylinder can be made by those skilled in the art without departing from the novel spirit and scope of this invention.
Number | Date | Country | Kind |
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200910249925.9 | Dec 2009 | CN | national |
200920293550.1 | Dec 2009 | CN | national |