MXPA97002580A - Condenser vapor condenser device with protected ventilated condenser of the congelac - Google Patents

Abstract

The present invention relates to an air-cooled two-stage steam condenser, comprising: a) main condensing means for partially condensing the steam, it has a common bottom discharge head that collects the excess steam and discharges the condensate into a drainage vessel b) ventilation condenser means coupled downstream of the main condenser to condense the excess vapor, comprising a plurality of rows of independent tubes that receive the excess vapor from a common top inlet head; c) tubular means to send the excess steam from the common bottom discharge head of the main condenser to the common top inlet head of the condenser or fan condensing means, wherein the excess steam and the resulting condensate flow together downward towards the condenser medium of the condenser. ventilation; d) a lower discharge head with compartments fixed to the middle; Ventilation unit, each compartment is coupled to the row of pipes to collect the condensate separately, e) separate drainage means coupled to each compartment to separate the separated condensate into the drainage container, and f) weir in the drainage vessel removing the condensate from the drainage vessel, the weir has an entry opening at a certain height above the discharge end of each of the drainage means

Description

VAPOR WITH VENTILATED CONDENSER PROTECTED FROM FREEZING DESCRIPTION OF THE INVENTION This invention pertains generally to heat transfer d systems for steam condensation and more particularly to a two-stage air-cooled steam condenser having frost protection performed by the removal of any return flow. to the individual heat exchange pipe. 10 Many industries use heat transfer equipment to condense water vapor. Such equipment is generally coupled to low pressure turbines at its outlet in order to condense the vapor to liquid and reuse it. A primary function of the steam condenser is provide a low return pressure, typically in the range of 1.0 to 6.00 inches of absolute Hg, at the turbine outlet to allow the turbine to function at its maximum efficiency. There are basically two types of steam condensers, those that are cooled by water and those that are cooled by air. Although water-cooled steam condensers are currently the dominant technology, air-cooled steam condensers are being used more frequently in order to meet ecological requirements. 25 One stage air cooled steam condensers are generally constructed in an A-shaped structure with a steam duct or head at the apex of the triangle and a fan at its base. This fan is used to force air through the two sides of the condenser tube on the inclined sides, the steam initially enters those groups of tubes at its upper end while the steam and the resulting condensate flows down to a common head lower. Each bundle of tubes generally consists of rows or multiple layers of individual tubes. As the air passes each successive row, its temperature increases naturally which results in a decrease in the differential temperature between the air and the next row, consequently less condensation occurs and a vapor flow occurs in each row successive of tubes which reduces the vapor pressure drop for that row of tubes. In condenser designs that have their several rows of tubes discharging to a lower common head, problems arise. These problems result from different different steam outlet pressures for each row of tubes. consequently steam and non-condensable gases from the high-pressure pipes (that is, those furthest from the fan) will enter the extreme opening of the pipes with less pressure (which are those closest to the fan, and are trapped there).

Non-condensable gases, typically air, are present in the system due to leaks through the pipe connections or in the seals of the turbines. Thus, since steam is penetrating both ends of a pipe, any condensate trapped there is subjected to freezing and breaking during the cold season. During the hot season, such entrapment results in thermal performance losses. Also those air pockets hinder the heat transfer surface of the tube by reducing its cooling capacity. Thus, the first challenge faced by air-cooled steam condensers is to sufficiently drain the condensate and remove any non-condensable gases from the pipes, as well as to simultaneously reduce to a minimum the pressure against the turbine. One solution to this problem is the one-stage capacitor of US Pat. 4, 129, 180 issued to Larinoff. In this one-stage arrangement, a complete and total separation of the different rows of tubes is maintained. Thus, rather than unloading to a common head, the different rows of tubes come out to a split lower head, to maintain their individual insulation. Each division of this lower head is then independently coupled to a common drain tank having water leg seals that balance the different pressures. In addition to maintain such complete and total separation between the rows of tubes, the ventilation lines used to ventilate the non-condensable gases that flow upwards in inclined tubes, are independent trajectories to individual vice pumps or ejectors for an eventual discharge to the atmosphere. The US patent to Larinoff 4, 903, 491 offers a variation of the water foot seal used in its one-stage condenser to balance the different pressures between the rows of separate tubes of a single-stage condenser. An alternative solution to this problem is the use of a two-stage capacitor. In such an arrangement, the first or main condenser is used to condense approximately two thirds of the steam entering with the resulting condensate and the excess steam is discharged to a common bottom header. Such excess steam flowing through the main condenser purges those rows of tubes. It also equals the pressure drop across each row of tubes to prevent backward flow into the tube. That excess steam (and any incondensable gas that is in it) is then sent to a secondary condenser, typically a deflection capacitor. This secondary capacitor is generally constructed in a manner similar to the main condenser as an A-shaped structure with a lower fan to force the air through the bundles of inclined tubes. Usually this secondary capacitor is configured with a surface that is one quarter to one third of the total condensing surface of the two-stage condenser, to ensure the passage of excess steam through the main condenser. In the deflagration condenser, steam and non-condensable gases enter the rows of tubes from a lower common inlet head and flow upward to a u >; common top discharge head. The resulting condensate, On the contrary, it flows down against the steam flow towards the common lower inlet head. This common bottom head then directs such condensate to a drain. It can also provide passage to an excess of steam from the main condenser to the lower head of the phlebotomist. Unfortunately, the previous two-stage design only works at its best with special design conditions of steam flow, ambient temperature, and air flow rate. any variation of those conditions of design alter the characteristics of the capacitor. For example, a reduction in steam flow will reduce the excess steam flowing through the main condenser to the secondary condenser. This reduction of the excess vapor gives as insulted variable pressures of the vapor that comes out and the Potential for vapor and non-condensable gases that flow backwards in some of the rows of tubes of either one of the capacitors or the two capacitors, both the main and the secondary. Another solution to the above problem of entrapment and freezing includes fixed holes or flap valves to equalize the pressure drop between the rows of tubes. Also some designs may vary the distance between the fins of the rows of tubes, 1 height of the fins, or the -f length with fin from row to row in an attempt to get the balanced condensation of vapor and pressure drop through the tube bundle. Other solutions include horizontally arranged pipes with multiple steps. In such an arrangement, the flow through each horizontal tube experiences a similar cooling potential and therefore has a similar condensation rate and also a similar rate of pressure drop. In any case, all the above solutions either act solely on the design conditions of the steam condenser or have a very high proportion of high cost / benefit, eliminating so its competitiveness. Thus it is an object of this invention to provide a vapor condenser which eliminates the problems associated with trapped non-condensable gases. Still another object of this invention is to provide a steam condenser that maintains a low pressure to the turbine but offer protection against freezing for the condensate that is collected. Yet another object of this invention is to provide a two-stage steam condenser that is capable of operating under a variety of conditions, not only design conditions and that is capable of providing protection from freezing under those different conditions. Another object is to reduce the need for withdrawal pipe for the condensate by reducing the manufacturing cost of the steam condenser. Still another object of this invention is to ensure the continuous purge of the rows of tubes by preventing any return flow. These and other objects and advantages of the invention will be presented with the description. This invention relates to a 2-stage steam condenser having a main condenser which partially condenses the temperature. This main condenser incorporates a common bottom discharge head that both collects the steam and discharges any condensate into a drain pan. A vented condenser is coupled downstream of this main condenser having the vent condenser size and shape to condense the excess vapor from the common bottom discharge head of the main condenser to the common top inlet head of the ventilation condenser where the steam excess and any resulting condensate flow together downward inside the ventilation condenser. A discharge head with compartments is fixed to the lower discharge region of the ventilation condenser, each compartment being coupled to a row of separate tubes for separately collecting the condensate within each compartment. A separate drain assembly is coupled to each compartment for separately discharging the particular condensate into the drain pan. A spout in the container removes the condensate and has an inlet opening with an elevation above the discharge end of each > f drainage set. 10 BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a pictorial view illustrating a part of a typical condenser of a stage with A structure showing a common direction of condensed vapor and non-condensable gas therethrough; FIGURE 2 is a pictorial view illustrating a part of a typical two-stage condenser having a main condenser and a secondary condenser together with a common direction of vapor flow, condensate and non-condensable gases; FIGURE 3 is a pictorial view of one embodiment of the two-stage steam condenser comprising the invention showing a main condenser and a ventilation condenser along which the flow direction of the steam, the condensate is carried out and the gases do not condensable; FIGURE 4 is a sectional view of the portion of the main capacitor of Figure 3 taken along lines 4-4 of Figure 3; FIGURE 5 is a sectional view of the portion of the ventilation condenser of Figure 3 taken along lines 5-5 of Figure 3; FIGURE 5A is an exploded pictorial view of a portion of Figure 5; FIGURE 6 is a pictorial view of another embodiment of the two-stage steam condenser according to the invention showing the main and the ventilation condenser together with the steam flow direction the condensate and the non-condensable gases; FIGURE 7 is a sectional view of the portion of the capacitor of the invention of Figure 6 taken along lines 7-7 of Figure 6; Referring initially to Fig. 1, a typical one-stage steam condenser characteristic of many single-stage condensers currently in use is shown. the condenser 10 is formed in an A-shape with the steam head 12 at the apex of the triangle and with a fan 14 forming the base of the triangle. Beams of inclined tubes 16 extend downwards from the head 12 and form opposite sides of the A-shaped structure. These bundles of inclined tubes discharge into a divided lower head T which keeps separate condensate lines and ventilation lines. 22, the independent condensate lines 20 from the head 18 flow to a common drain incorporating water leg seals with the purpose of balancing the different pressures within each row of tubes 24. The independent ventilation lines 22 from the head lower 18 have separate routes to individual vice pumps or ejectors for eventual discharge to the ^^ w atmosphere. As shown, condensate 26 and steam flow in the same direction from the head 12 towards the lower head 18 while the air 28 flows upwards through the fan 14. Referring to Figure 2, a typical two-stage condenser 40 characteristic of many of the condesadores of two stages in current use. These condensers 40 consist of the main capacitor 42 and the downstream secondary capacitor 44 which is typically a decontaminating condenser. Generally the main condenser 42 comprises approximately two thirds of the surface of the exchanger required to completely condense the incoming steam as long as the secondary condenser 44 comprises the remainder of the surface to be able to fully condense the excess vapor received from the main steam head 46. Since the main condenser 42 has no size to condense All steam entering 48 in excess steam 50 as well as another condensate 52 flows together downward to a lower header 54 which is common. This excess vapor 50 is intended to equalize the pressure drop across each row of tube 56 in the main condenser 42 to prevent any backward flow in any of the rows of tubes 56. Then the steam 50 is sent by a common head 54 to the lower entrance of a dephlegmator 44. In the dephlegmator 44 this steam 50 and any non-condensable gas 58 (usually air entering the system through the pipe connections or seals of the equipment) flows towards above as long as the resulting condensate 60 flows countercurrent to the common head 54. Subsequently, the condensate 60 is removed from the lower head 54 by normal channels. Non-condensable gases 58 enter the upper discharge head 61 and are discharged by a common line 63. This design does not include any type of pressure equalizing mechanism to balance the difference in pressure that exists between the various rows of tubes 62 of the secondary capacitor 44. Consequently in the condenser 44 it is possible that the highest pressure of a row 62 (those further apart of the fan) causes backward flow in other rows 62 (this is in those closest to the fan). Furthermore, in such typical capacitors 40 it is likely that in the condenser 42 the downstream tubes furthest away from the steam turbine will be subjected to less pressure than the current pipes. above, closer to the steam turbine, showing the? possibility of a backward flow in those tubes trapping there the condensate 52. Additionally in the main condenser 42 and in the lower part of the stream the backward flow would present from the upper tubes to the lower 5, that is from the more away from those closest to the fan. Thus, if the operating conditions of the two-stage condenser 40 are not maintained as intended, it is possible that the vapor outlet pressure 50 from the condenser 42 varies creating the potential for vapor 50 and non-condensable gas 58 to flow backward in one or more rows 56 of the main condenser (see area 64). Additionally, such a variation in steam outlet pressure 50 can allow the return of steam 50 and non-condensable gas to one or more rows 62 of the secondary capacitor 44 (see area 66). Thus the possible problem of freezing and rupture of the tube remains. Referring now to Figures 3-5, one embodiment of the invention is shown which is designed to overcome the The disadvantages of the typical single-stage and two-stage capacitors shown in FIGS. 1 and 2. According to the invention, the two-stage, air-cooled steam condenser 70 is constructed with the main condenser 72 in typical A-shape. having the steam head 74 at the apex of the triangle and with one or more fans 76 that form its base.

The bundles of inclined tubes 78 forming an angle generally incorporate 4 rows of tube 80, which may be more or less, extending downwardly from the head 74 and forming opposite sides of the triangle of the main capacitor 72. Each of these Tubes 80 drains into a lower common head attached to condenser 72 in the normal manner. The vapor 84 from the head 74 and any condensate 86 flows downward through the main condenser 72 towards the lower common head 82. The heat transfer surface of the condenser 72 and the air flow of the fan 76 are designed so that in a In a wide range of operating conditions, the vapor 84 does not condense completely within the main condenser 72. Instead, the vapor 88 continuously leaves each tubular row 80 of each beam 78 continuously purging those rows 80 of the condenser 72 from any non-condensable gas. That purge also equals the pressure in common bottom header 82. Generally in main condenser 72 it is constructed in modules 90 (typically 2.5 to 4 meters wide) to facilitate transportation and construction. This type of capacitor 72 is commonly used and is similar to that described in relation to FIG. 2. The novel aspects of the air-cooled steam condenser 70 are based on the configuration of the adjacent ventilation condenser 92 which completely condenses the vapor 88. The steam 88 and the non-condensable gas 94 from the condenser 72 is sent in this case in the tube 96 to the upper part of the condenser 92. This is contrary to what is known where the product is directed to the lower part of the secondary condenser (see figure 2). The ventilation condenser 92 according to the invention is protected from freezing by fitting rows of independent tubes 102 individually into a condenser flow module 98. Several modules 98 each of 2. 5 to 4 meters wide to facilitate the transport and construction combine to form the ventilation condenser 92. Within the condenser 92 the vapor 88 and the resulting condensate 100 flow together downwardly from the upper region of the condenser 92 (as opposed to the arrangement of figure 2 which has both products flowing in opposite directions). The fluid within each tubular row 102 of the condenser 92 remains separated from that in the rows 102 by means of the independent air removal system 104 and by the water leg seals in the different drain pipe 106. These independent rows 102 and the systems 104 prevent any return of the vapor 88 in rows 102 as well as any trapping of non-condensable gases 44 which can lead to freezing the separate drain pipe 106 is coupled to its respective lower discharge head compartment 108. This pipe 106 directs the resulting condensate 100 from the condenser 92 to the tube 110 which is located below the discharge head 108. The height of the water or condensate 100 in each drain pipe 106 balances the differences in pressure between the split discharge heads 108. However for the water seal provided by the pipe 106 to operate as desired, the tube 110 must remain completely filled to prevent any exchange of gas between the adjacent drain pipe 106 and the lower discharge heads 108. Such a water level in the common pipe 110 is maintained by the pour pipe 112 located in the container 114 This pourer 112 is designed with its open upper end 116 on the common tube 110. Maintaining such a level of water in the tube 110 also prevents some non-condensed vapor 88 from the head 82 of the main condenser 72 from entering the split head 108. of the cooling condenser 92. However, since it is probable that the condenser 70 needs maintenance, the drainage of this liquid the common tube 110 and from the head 82 of the main condenser 72 is carried out by small holes 118 around the base of the pouring tube 112 inside the container 114. These small holes 118 will be sized to drain the liquid from the container 114 provided that the The heater 70 does not work but is too small to pass all the liquid flowing to the open end 116 of the pourer 112. Thus, as shown, the head §f? bottom common 82 of the main condenser is coupled to the drain vessel 114, so that the collected condensate 86 comes out either from the end 116 of the pourer 112 or the holes 118 in the pourer tube referring to FIGS. 5 and 5A. Air removal of the condenser 92 has vent pipes 120 having routes from the different compartments of the discharge head 108 to several finned tubes located first in the outer or upper rows 102 of the condenser 92. For example in Figure 5A the ventilation tube 120 extends from the lower compartment 122 of the head 108 and arrives at a finned tube in the third row 102 (counting from bottom to top) of the ventilation condenser 92. Since the non-condensable gas 94 is concentrate in capacitor 92, it is likely that multiple tubes 120 will be required for each split discharge head 108 within each module 98. The individual finned tubes of the several rows 102 allow the steam 88 to condense and flow down to the head 108, while the non-condensable gas 94 flows towards up to the top of the condenser 92, where this air removal system 104 is ejected maintains the independence of each row 102 by connecting only tubes with individual fins within a beam 98 or different beams 98, located in the same row 102. Thus the capacitor 92 that has 4 rows 102 with also 4 tubes 124 for removal of air associated with the air removal system 104. Each of these tubes 124 will have a separate route to the ejector or vice pump (not shown) that discharges this non-condensable gas 94 into the atmosphere. Referring now to Figures 6 and 7 there is shown an alternate embodiment of that presented in Figures 3-5. This alternative mode of a two-stage air-cooled condenser 70 does not send steam 88 and gases 94 through the tube 96 to the upper part of the ventilation condenser 92 as previously mentioned. Instead, the modality The alternative fits several rows of independent deflectors 126 to form the new ventilation condenser 128. In each of these deflectors 126 the vapor 88 and the non-condensable gases 94 flow together upward while the condensate 100 flows downward. This arrangement eliminates the the need for the drain pipe 106 and the common pipe 110 of Figures 3-5 when replacing a common header 130 which -fe ^ is divided between the various dephylmeters 126. This simplifies the condensate and steam pipe between the main condenser 72 and this ventilation condenser 128. of a, new design. These dephlegmators 126 are different from the conventional dephlegmator 44 of FIG. 2 in that each row of these dephlegmator 126 has an independent air removal system. This independent system 132 prevents any return of vapors 88 to the lower ends of the rows of f ^^ each dephlegmator 126. In addition, the air removal system 132 prevents non-condensable gases 94 from coming together in any row which could cause freezing and rupture of the row. tubes Other alternative designs of the capacitor 70 of the invention may include different proportions of the heat transfer surface between the main capacitor 72 and the ventilation capacitors 92 or 128. These embodiments described herein illustrate capacitors of ventilation 92 and 128 having approximately one third of the total heat transfer surface of the condenser 70 but this value may vary depending on the amount of freeze protection desired or needed. By increasing the proportion of the surface of the capacitors 92 or 128 will improve the freeze protection but will increase the cost of the steam condenser 70. So although four rows of independent tubes are shown in the condensers 92 and 128, more or less can be used depending on the conditions and specifications It is also possible for the main capacitor 72 to have a different number of rows 80 from that of the ventilation capacitors 92 and / or 128. An advantage associated with these modes of the capacitor 70 includes a reduction in the need for tubing for the condensate and air removal system compared to existing models. Such reduction on the. Cone pipe results in significant savings. In addition these new designs for the capacitor 70 water-cooled steam eliminates the possibility of freezing in the 92 or 128 cooling condensers. This solves a major problem that has damaged the designs of the steam condensers in the past. Finally, the steam condenser 70 can be configured different from the design of the structure A. For example, the structure A can be inverted so that the fans are on the upper part rather than the lower part of the condenser. This would result in a design for the bundles of condenser tubes. Also these bundles of tubes can be tilted at a different angle than the typical 60 ° presented here. Alternatively, fans would not be required for systems that rely on a natural air stream.

Claims (12)

1. CLAIMS 1. -An air-cooled two-stage steam condenser, comprising: a) main condensing means for partially condensing the vapor, it has a common bottom discharge head that collects the excess steam and discharges the condensate into a container drainage; b) ventilation condenser means coupled downstream of the main condenser to condense the excess vapor, comprising a plurality of rows of independent tubes that receive the excess steam from a common top inlet head; c) tubular means for sending excess steam from the lower common discharge head of the main condenser to the common top inlet head of the condenser or fan condensing means, wherein the excess steam and the resulting condensate flow together downwardly towards the condensing means of ventilation; d) a lower discharge head with compartments fixed to the ventilation condenser means, each compartment is coupled to the row of tubes to separately collect the condensate; e) separate drainage means coupled to each compartment for separately discharging the segregated condensate to the drainage vessel; and f) landfill means in the drainage vessel for removing the condensate from the drainage vessel, the weir has an entry opening at a certain height above the discharge end of each of the drainage means.
2. 2. - The steam condenser according to claim 1, characterized in that it comprises drainage means having an intermediate tube of the lower discharge head in compartments and the drainage container or tray, the tube discharges into the drainage tray at a lower height than that of the weir entrance opening.
3. 3. The steam condenser according to claim 2, characterized in that it comprises at least one drainage opening inside the drain pan or container at the base of the landfill.
4. 4. The steam condenser according to claim 3, characterized in that the drainage pipe empties into the drainage container.
5. 5. - The steam condenser according to claim 4, characterized in that the main condensing means and the condensing ventilation means are modular.
6. 6. The steam condenser according to claim 5, characterized in that there are air ejector means coupled to each compartment of the lower discharge head f of the ventilation condenser for independent discharge of the air, which discharge is carried out countercurrently of the excess flow of steam and the resulting condensate in the ventilation condenser
7. 7. A method for condensing steam in two stages in an air-cooled two-stage steam condenser comprising the steps of: a; partially condensing steam in a main condenser assembly, having a common bottom discharge head 10 that both collects the excess steam and discharges the condensate to a drain vessel; b) Condensate the excess steam in a set of ventilation condenser coupled downstream of the main condenser assembly, ventilation condenser that 15 comprises a plurality of rows of independent tubes that receive the excess steam from a common top inlet head; c) sending excess steam through a pipe extending from the common bottom discharge head of the 20 main condenser assembly to the common top inlet head of the ventilation condenser assembly, the excess vapor and the resulting condensate then flowing concurrently downwardly into the ventilation condenser assembly; 25 d) Attach a lower discharge head with compartments to the ventilation condenser assembly, each compartment being coupled to a row of tubes to separately collect the condensate; and coupling separate drainage means to each compartment to separately discharge the segregated condensate to the drainage vessel; f) constructing and arranging a pouring assembly in the drainage vessel to remove the condensate from the drainage vessel, the pour assembly having an entry opening at a height above the discharge end of each of the drainage means.
8. 8. Method according to claim 7, characterized in that it comprises the step of constructing and arranging the drainage means with an intermediate tube between the lower discharge head with compartments and the drainage vessel, the tube discharging into the drainage vessel at a height lower than the entrance opening of the landfill.
9. 9. Method according to claim 8, characterized in that it further comprises the step of constructing and arranging at least one drainage opening inside the drainage vessel at the base of the landfill assembly.
10. 10. - Method according to claim 9, characterized in that it comprises the step of draining the pipe assembly towards the drainage vessel.
11. 11. - Method according to claim 10, characterized in that it comprises the step of constructing and arranging the main condenser assembly and the ventilation condenser assembly as a combination of separate modules.
12. 12. - Method according to claim 11 characterized in that it further comprises the step of coupling an air ejector assembly to each compartment of the lower discharge head of the ventilation condenser assembly for independent air discharge, the air discharge is performed countercurrent of the excess vapor flow and the resulting condensate in the ventilation condenser assembly.