MXPA97001495A - Va condenser appliance - Google Patents

Abstract

The present invention discloses an air vapor condenser which also employs thermal tube technology in order to provide tubes that are freeze proof under any environmental conditions and offer a simple approach for handling non-condensable gases. The steam flows through the main condenser with the steam and condensate flowing concurrently downwards. The surface area of heat transfer and the air flow of the fan are so that the steam condenses completely and the steam exits continuously from each row of tubes. The continuous flow of steam cleans these rows of non-condensable gases. The excess steam flows into the lower head towards a secondary condenser section that uses the thermal tubes. In the secondary condenser section, the excess steam condenses on the external surface on the side of the thermal tubes buffer. The non-condensable gases that remain in the lower head are ventilated with an air removal system similar to conventional condensers. The condensate in the lower head is collected for reuse in the power generation cycle

Description

VAPOR CONDENSER APPARATUS Field of the Invention The invention relates generally to steam condensers and more particularly to steam condensers that combine the use of vapor condensing technology in air-cooled vacuum section with thermal pipe technology. The air-cooled steam condensers used in the steam power generation cycle are typically arranged in an A-frame construction with a fan at the base and a group of condenser tubes inclined on each side. Air circulates through the fan and through several sections of the steam condenser. The steam inlet is at the top of each group and the steam and condensed flow are concurrently downward. Typically, there are four rows of tubes in each condenser group. When the air flows through the four rows, the air temperature increases and the temperature difference between the condensation vapor and the air decreases. The lower temperature difference for each successive row of tubes results in less condensation. Since the condensate and steam flows are smaller for each successive row of tubes, the reduction of the two-phase flow pressure is also smaller for each row tubes. In case the rows of tubes are discharged in a common rear head, the differences in the exit pressures of the rows of tubes are resolved by the vapor and the non-condensable gases in the rear head that enters the ends of the rows of tubes that have a lower pressure. Since the rows of lower tubes have lower outlet pressures, they have a vapor that enters both ends and for a time gathers the non-condensable gases in the tubes. These cavities of non-condensable gases block the local vapor flow, allowing the condensate to freeze during a cold climate, which causes a rupture of the tube. Non-condensable gases are normally ventilated from the rear head with vacuum pumps or air ejectors. To overcome this problem, the classic solution has been to design the excess steam flow through each row of tubes. Excess steam prevents the accumulation of non-condensable gases and keeps condensate temperatures above freezing. This excess vapor, typically from twenty to thirty-three percent of the total steam flow, is condensed in a secondary or ventilation condenser. The typical ventilation condenser is a deflegmador (reflux condenser), which has a vapor that flows into an inclined tube, condenses the walls of the tube and drains the condensate downwards.

Noncondensibles flow up the tube and are removed by vacuum pumps or air ejectors. The problems of freezing of the steam condenser have also been overcome in the past through the use of thermal tubes. The condensate was collected at the bottom of the steam duct and returned to the boiler to be reused. These approaches are subject to some limitations and do not necessarily offer a simple approach for the handling of non-condensable gases. The invention relates to the limitations of the prior art. What is provided is an air cooled condenser of steam that is also used by a technology of thermal tubes, in order to be freeze proof under any environmental condition and offer a simple approach for the handling of non-condensable gases . The steam flows through the main condenser with the steam and condensate flowing concurrently downwards. The surface area of heat transfer and air flow are designed so that, within the range of operating conditions, all the steam does not condense completely and the vapor continuously exits through each row of tubes. This continuous steam flow cleans these rows of non-condensable gases. The excess steam flows in the lower head to a secondary condenser section that uses the thermal tubes. In the secondary condenser section, the excess steam condenses on the external lateral surface of the evaporator of the thermal tubes. The non-condensable gases that remain in the lower head are ventilated with an air removal system similar to that of conventional condensers. The condensate in the lower header is drained to a condensate tank for reuse in the power generation cycle. BRIEF DESCRIPTION OF THE DRAWINGS For a further understanding of the nature and objects of the present invention, reference will be made to the following description, taken in conjunction with the accompanying drawing, in which similar parts are given with similar reference numbers, and wherein: Figure 1 illustrates an air-cooled steam condenser of the prior art. Figure 2 illustrates an air-cooled steam condenser of the prior art. Figure 3 illustrates an air-cooled steam condenser of the prior art. Figure 4 illustrates the invention. Figure 5 illustrates an alternative embodiment of the invention. Figure 6 illustrates a second alternate embodiment of the invention.

Figure 7 is a sectional view illustrating a tube of the thermal tubes used in the invention. Figure 8 is a sectional view of an alternate embodiment of a heat pipe that can be employed with the invention. Figure 9 is a sectional view illustrating an alternative embodiment of the lower steam head of the invention. As seen in the prior art illustration of Figure 1, air-cooled steam condensers are typically arranged in a construction Frame-A with a fan 10 at the base and a group of inclined condenser tubes 12 on each side. Air flows through the fan through several sections of the steam condenser. The steam from the steam turbine 14 is directed to an upper steam head 16, which provides a steam inlet at the top of each group 12. The steam and condensate flow concurrently downward in the group towards the lower head or back 18. An air ejector or vacuum pump is used to vent the non-condensable gases from the back head 18. The condensate is collected in the tank 22 and is directed towards the condensate pumps, not shown, for reuse. Figure 2 illustrates a solution of the prior art to prevent condensate freezing. The group of condenser tubes 12 is designed to cause an excess of steam flow through each row of tubes. The excess steam prevents the accumulation of non-condensable gases and keeps the condensate temperatures above freezing. This excess steam is condensed in a secondary or ventilating condenser 24. The typical ventilation condenser 24 is a deflegmator (reflux condenser), which has a vapor that flows up into an inclined tube, condenses on the walls of the tube and the condensate is drained downwards. The non-condensable gases flow up the tube and are removed by vacuum pumps or air ejectors. Figure 3 also illustrates a solution of the prior art to prevent condensate freezing. The heat pipes 26 are set in a Y-shape. The side of the evaporator of the heat pipes are enclosed in a steam head 28. The steam is condensed as it passes through the side of the evaporator of the heat pipes 26. The condensate is collects in the lower part of the head 28 and returns to the boiler to be used again. The fan 10 causes the induced air to flow through the sides of the condenser of the thermal tubes to cause cooling and recondensing of the working fluid contained in the thermal tubes. The present invention is generally indicated by the number 30 in Figure 4. The steam condenser apparatus 30 generally comprises a main condenser 32, a lower head 34 and a secondary condenser 36. The main condenser 32 is formed of a steam head upper 38 and one or more groups of tubes 40. The upper steam head 38 receives the steam from the steam turbine 42 by means of a line or pipe 44 and then directs the steam to the groups of tubes 40. Each group of pipe 40 is similar to the groups of generally known tubes and are used in the industry since several rows of tubes, usually four, are provided for receiving and condensing the steam. The main difference in the groups of tubes of the present invention from the prior art is that they are not designed to condense as much steam as possible. Instead of the heat transfer surface area and the air flow of the fan from the fan 46 being designed so that, during the range of operating conditions, all the steam does not fully condense and the vapor exits continuously from the base of each row of tubes to the lower head 34. In the preferred embodiment, it is used from sixty-seventy to eighty percent of the available surface area in groups of tubes 40. This surface area, combined with the air flow of the fan, results in approximately twenty to eighty percent of the steam being condensed in the main condenser 32. The continuous flow of steam cleans the rows of tubes in a main condenser 32 of the non-condensable gases. The excess non-condensed vapor and the flow of non-condensable gases flow into the lower head 34 and then to the secondary condenser 36. The secondary condenser 36 is in fluid communication with the lower head 34 and is placed in line with the main condenser 32 The heat pipes 48 are placed in the secondary condenser 36 so that the side of the evaporator of each heat pipe is at the lower end of the secondary condenser 36 and extends into the lower head 34. The side of the condenser of each heat pipe is placed in the direction of the upper end of the secondary condenser 36. In this manner, the non-condensed vapor of the main condenser 32 condenses on the side of the evaporator of the thermal tubes 48 and flows out of the lower head 34 through the condensate drain 50. Non-contactable gases are vented outside with an ejector, indicated by the number 52. Figure 5 illustrates an alternate modality of The invention, wherein the main capacitor 32 and the secondary capacitor 36 are oriented in a configuration configured in place of an in-line configuration. As mentioned above, the invention condenses the excess vapor in the secondary condenser 36. The non-condensable gases are vented out by means of the lines or tubes 54. Figure 6 illustrates another alternate embodiment of the invention, wherein the main condensers and secondary described above are consolidated into a single condenser 56. The single condenser 56 includes tubes with conventional fins 58 which direct the steam flow from the upper parts towards the lower part and to the thermal tubes 26. As mentioned above, the surface area The heat transfer and the fan air flow are designed so that, during the range of operating conditions, all steam does not condense in the tubes 58. The continuous steam flow cleans the tubes 58 from the non-exhaust gases. condensable. The remaining steam exiting from the bottom of the tubes 58 is condensed by the heat or heat pipes 26, which have their costly evaporators extended below the outlet end of the tubes 58 in the bottom head 34. The condensate is drained from the condensate drain 50 to be collected for reuse. The non-condensable gases are removed by means of the lines or ventilation pipes 54. Figure 6 illustrates four rows of tubes, with thermal tubes 26 that are in the first row or in the lower row. It will be understood that the thermal tubes 26 can be placed in any row of the group of tubes. Figure 7 is a detailed sectional view of a thermal tube 26 and a lower head 34 as used in the invention. The thermal tubes 26 may be made of flat, elliptical, round, ovoid tubes that may contain a wick or may not have one. The thermal tubes 26 are sealed at both ends and contain a predetermined amount of heat transfer fluid 60 at a predetermined vapor pressure. The fluid used will depend on the application and the conditions. Examples of heat transfer fluid used in different thermal tube applications are, but are not limited to, methanol, ammonium, and freon. The heat transfer fluid 60 normally reside in the evaporator section 62 of the heat pipe 26. When the heat flows into the evaporator section 62, the heat transfer fluid 60 evaporates, removing heat from the steam and causing condensation, and travels upward to the condenser section 64, where the fluid is cooled and condensed, releasing the heat of the fluid in the air flow. The condensate of the heat transfer fluid returns to the evaporator section 62 by gravity of the flow. The condenser section 64 may be provided with fins 66 to provide a large heat rejection surface area. The fins 66 can be extruded, interleaved or wrapped in aluminum or steel and can be solid or serrated depending on the requirements of heat transfer and pressure reduction. The heat pipes 26 can be placed in in-line or triangular pipe passages depending on the pressure reduction and heat transfer requirements of the system. For improved heat transfer and corrosion resistance operation, Figure 8 illustrates a heat pipe 26 having the outer diameter of the jacket evaporator section having a low friction coating 68, such as polytetrafluoroethylene. The low friction coating promotes low condensation, increasing the heat transfer rate of condensation by approximately one order of magnitude. In addition, the coating provides a corrosion test limit that allows the use of cheap carbon steel-based tubes for the thermal tubes 26. Figures 9 and 10 illustrate one embodiment of a lower head 34 that is provided with a plurality of thermal wells or jackets 70, which are welded directly with the lower head 34 to form a waterproof seal. Each jacket 70 is dimensioned to provide a small sliding fit space between the internal diameter of the jacket 70 and the outer diameter of the evaporator section of the thermal tube 26 to reduce the thermal resistance. In case it is required to improve the thermal transport, a thermally conductive substance, such as grease or a liquid can be used to fill the ring. The thermal tubes 26 are held in place by gravity and the tube supports are commonly found in the condenser tube group frame. This provides other elements to eliminate contact corrosion of the thermal tubes 26 with the steam. As referred to above, the exterior of the sleeves 70 may be coated with a low friction coating to promote low condensation, increasing the heat transfer rate. In operation, the steam received in the upper head 38 flows to the tubes in the groups of tubes 40, where part of the steam is condensed and flows to the lower head 34. The steam vapor flows out of the tubes in the lower head 34 clean the tubes of non-condensable gases. The rest of the steam is condensed in the evaporator section 62 of the heat pipes 26. The non-condensable gases are removed by means of the ventilation lines and / or the vacuum pumps. The arrangement of the tubes and the thermal tubes cause a constant flow of steam through the tubes in the groups of tubes to provide freeze-proof tubes in the groups of tubes. The only possible freezing in the design of the invention is on the outside of the section of the thermal tube located in the lower head. Since it occurs on the outside of the thermal tubes, it will not damage the thermal tubes. The lower head embodiment of Figure 9 provides the advantage of being able to remove and install the thermal tubes in the field without the need to cut and re-weld the difficult seal weld between the thermal tube 26 and the lower head 34. Because many variants and different modalities can be made within the scope of the inventive concept taught herein, and because they can make many modifications to the detailed embodiment of the present one in accordance with the descriptive requirements of the law, it is understood that The details of the present should be interpreted as illustrative and not in a limiting sense.

Claims (3)

1. NOVELTY OF THE INVENTION Having described the invention as above, the content of the following is considered to be our property: CLAIMS 1. A steam condensing apparatus, comprising: a. a superior steam head; b. a main condenser in fluid communication with said upper steam head, said main condenser is designed so that only a predetermined portion of the steam flow condenses therethrough; c. a lower steam head in fluid communication with said main condenser; d. a secondary capacitor in fluid communication with said lower steam head; and e. a plurality of thermal tubes received in said secondary condenser causing condensation of the steam to not condense in said main condenser.
2. 2. The steam condenser apparatus of claim 1, wherein said main condenser is designed such that approximately twenty to eighty percent of the steam flow condenses therethrough.
3. 3. The steam condenser apparatus of claim 1, wherein said main capacitor and said secondary capacitor are arranged in an in-line configuration. . The steam condenser apparatus of claim 1, wherein said main condenser and said secondary condenser are arranged in a configuration configured in W. The steam condenser apparatus of claim 1, wherein said thermal tubes are provided with a coating of low friction in its evaporating section. 6. The steam condenser apparatus of claim 1, wherein said lower steam head is provided with a plurality of liners that extend into the lower steam head and are dimensioned to receive the evaporator section of one of the thermal tubes. 7. A steam condensing device, comprising: a. a superior steam head; b. a main condenser in fluid communication with said upper steam head, said main condenser is designed so that approximately twenty to eighty percent of the vapor flow condenses therethrough; c. a lower steam head in fluid communication with said main condenser; d. a secondary capacitor in fluid communication with said lower steam head and placed in line with said main condenser; and e. a plurality of thermal tubes received in said secondary condenser causing condensation of the steam to not condense in said main condenser. The steam condenser apparatus of claim 7, wherein said thermal tubes are provided with a lower friction coating in their evaporator section. The steam condenser apparatus of claim 7, wherein said lower steam head is provided with a plurality of liners that extend into the lower steam head and are dimensioned to receive the evaporator section of one of the thermal tubes. 10. A steam condensing apparatus, comprising: a. a superior steam head; b. a lower steam head; c. an adjacent condenser positioned between said upper and lower steam heads; d. a plurality of steam tubes placed in said condenser and in fluid communication with said upper steam head and said lower steam head; and e. a plurality of thermal tubes placed in said condenser so that the evaporating section of said thermal tubes extends within the lower steam head. The steam condenser apparatus of claim 10, wherein the evaporating section of each of said thermal tubes is provided with a lower friction coating. The steam condenser apparatus of claim 10, wherein said lower steam head is provided with a plurality of liners that extend into the lower steam head and are dimensioned to receive the evaporator section of one of the thermal tubes.