RU2305227C1 - Steam-water heat exchanger - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: steam-water heat exchanger comprises housing with branch pipes for supplying steam and discharging its condensate, distributing water chamber that is provided with branch pipes for supplying and discharging water to be heated, and piping system mounted in the casing and provided with vertical baffles and straight or U-shaped tubes defining the heat exchanging surface. The baffles inclined to the horizon and provided with condensate collectors at the bottom part are interposed between the vertical baffles. The vertical drain passages are connected with the condensate collectors. The bottom end of the drain passage connected with the bottom condensate collector underlies the level of condensate in the housing.

EFFECT: enhanced efficiency.

4 dwg

Description

The invention relates to the field of energy and can be used in heat exchangers of regenerative systems, steam turbines or in heat exchangers of heat supply systems designed to heat water by condensation of steam on the pipes of the heat exchange surface and its supercooling.

Known heater with a horizontal tube bundle, comprising a housing with nozzles for supplying steam and draining its condensate, a pipe system with vertical and radially mounted horizontal partitions, a distribution water chamber with inlets and outlets of heated water and a "rotary" water chamber (Heater PGS-2300 -3-8-II, Industry Catalog Heat Transfer Equipment for Steam Turbine Units, Moscow: NIIEINFORMENERGOMASH, 1984, p. 244-245, Fig. 193).

A disadvantage of the known heater is the flooding of steam of the underlying rows of pipes from above, which increases the thickness of the condensate film and affects the heat transfer. In addition, the condensate supercooling achieved by contacting the steam condensate film with the pipes of the heat exchange surface is lost when the supercooled condensate is drained from the radially installed partitions due to its heating by the steam flow. Such heating is suitable for heat exchangers operating at a vapor pressure below atmospheric, or in the case of non-condensable gases (air) entering the heat exchanger together with heating steam. Loss of supercooling of the steam condensate, if it is necessary to supercool it, will require an additional heat exchange surface for this purpose.

A horizontal surface heater is known comprising a water chamber with inlet and outlet nozzles of heated water, housings are installed on both sides of the chamber, in which pipe systems with horizontal U-shaped pipes and vertical partitions are placed, the lower rows of pipes are placed in the casing and are used for condensate subcooling steam (Heater PN-1200-120-17A Catalog 8-78 part II. Heat exchange equipment. - M .: NIIEINFORMENERGOMASH, sheet 137).

By the totality of the features, this known technical solution is the closest to the claimed one and is taken as a prototype.

A disadvantage of the known heater adopted for the prototype is that condensate is poured with steam of the underlying horizontal pipes from the overlying pipes, which, given the large number of horizontal rows of pipes, affects heat transfer due to an increase in the thickness of the condensate film flowing from the pipes. This film on the pipes is supercooled, but then with a free fall in the form of jets, drops on the condensate level in the body are heated almost to the saturation temperature and enter the condensate cooler, under which the lower rows of pipes of the first stroke of the heated water are highlighted. Thus, the condensate, which is initially supercooled upon contact of its film with the pipes of the heat exchange surface, is then heated by the steam stream when it falls in the form of jets and drops to the level of condensate in the body, then for cooling, the condensate enters the heat exchange surface of the built-in condensate cooler, which is additionally highlighted by the installation of the body. At the same time, increased manufacturing requirements are imposed on the density of the casing. The built-in condensate cooler does not allow large fluctuations in the level of condensate in the housing, in which steam can enter the annulus, which can lead to water hammering and destruction of the cooler.

It is known that in steam-water heat exchangers during steam condensation its “natural” supercooling occurs due to the contact of the condensate film with the heating surface of the heat exchange tubes. This subcooling is the greater, the lower the temperature of the heated water in the pipes. However, this “natural” supercooling of steam condensate is lost when the condensate film is torn off the pipe surface and in free fall, ultimately, to the level of condensate in the body, which already drops in the form of droplets, the film is heated by the steam stream to the saturation temperature. If it is necessary to cool this condensate, an additional heat exchange surface is released in the built-in or external cooler. In the latter case, this is a separate water-water heat exchanger with connecting pipelines and fittings installed on them. The built-in condensate cooler requires an increased quality of workmanship and does not allow steam to enter the annular space during level fluctuations in the casing to avoid water hammer. Thickening of the condensate film on each subsequent vertical row of pipes affects heat transfer. Therefore, the organization of the intermediate drainage of steam condensate from horizontal pipes to the heat exchange surface in order to reduce the flooding of the underlying pipes from the overlying pipes and to reduce the film thickness is one of the technical solutions that increase the efficiency of the heat exchangers.

The claimed technical solution allows to reduce flooding, that is, to reduce the thickness of the condensate film on the heat exchange surface lying in the rows of pipes, the condensate draining from the overlying pipes, to ensure and save until the heat exchanger exits the heat exchange surface under the built-in or external condensate cooler under "natural" supercooling steam condensate, additionally increase the "natural" subcooling of the condensate draining from the partitions located at an angle to the horizon, and keep this value of supercooling until the condensate exits the heater, provide for the organization on the part of the pipes of the first stroke of the heated water of the surface cooler.

The claimed technical solution due to simple design measures allows to increase the efficiency of the heat exchanger by reducing the film thickness on the pipes of the heat transfer surface (ultimately increases the heat transfer coefficient), without creating special surface areas - condensate coolers, condensate supercooling due to the preservation of "natural" supercooling and additional cooling of the condensate when it drains along partitions inclined to the horizon, which also allows to increase heat th heat exchanger efficiency and optimize the operating conditions regulating the condensate level in the valve body.

A steam-water heat exchanger is proposed, including a casing with steam inlet and condensate outlet pipes, a distribution water chamber with heated water inlet and outlet pipes, a pipe system with vertical partitions, straight or U-shaped pipes of the heat exchange surface, installed between the vertical partitions oblique partitions with condensate collectors in their lower part at an angle to the horizon, and vertical drain channels connecting them to the condensate collectors a forward and the lower end of the outflow conduit attached to the lower condensate is disposed below the condensate level in the housing.

The invention is illustrated by drawings, in which Fig. 1 shows a steam-water horizontal heat exchanger, a longitudinal section, in Fig. 2 is a transverse section B-B, in Fig. 3 is a view A in Fig. 1, in Fig. 4 is a node C in Fig. 2.

Steam-water heat exchanger includes a housing 1 with a pipe for steam inlet 2 and its condensate outlet 3, a distribution water chamber 4 with pipes for the input 5 and output 6 of heated water, a pipe board 7, a casing 8 installed in the housing 1 with a pipe system 9 located therein, composed of straight or U-shaped pipes (U-shaped pipes are shown in Fig. 1) with vertical partitions 10, between which horizontal partitions 11 are installed at an angle to the horizontal along the entire length of the pipe system, in the lower part of which there are horizontal condensate collectors 12 with openings for entering condensate flowing down from the partitions 11 into them. The condensate collectors 12 are interconnected by vertical drain channels 13, and the lower end of the drain channel connected to the lower condensate collector 12 is located below the condensate level in the housing 1. To discharge steam condensate from the lower part of the casing 8, there are nozzles 14 with a partition 15 placed in them, and to exit the vapor-air mixture (air) from the housing 1, a horizontal perforated pipe 16 is installed, in front of which the pipes of the heat exchange surface of the first stroke of the heated water are located in a volume limited to Clones baffle 11, housing portion 8, the partitions 15 and 17. For the removal of vapor (air) from the pipe system through a bore in the tube sheet 7 is mounted on the pipe 18. The horizontal partition 11 to the holes in the condensate trap 12 installed bumpers 19.

Steam-water heat exchanger operates as follows. The stream of heated water through the pipe 5 enters the distribution water chamber 4, then into the pipes of the heat exchange surface of the pipe system 9, from which the water heated during steam condensation and supercooling enters the water chamber 4 and is removed from the heat exchanger through the pipe 6. The heating steam stream through the pipe 2 enters the housing 1, where in the gap between the pipes of the heat exchange surface and the housing extends along the entire length of the pipe system 9. From this gap, the steam is directed to the pipes of the latter (in Fig. 1 of the second stroke), and then the first the first stroke of the heated water. During the movement of heating steam in the channels formed by the casing 8, partitions 10 and 11, the steam condenses on the pipes of the heat exchange surface, transferring condensation heat to the heated water flowing in the pipes. After the steam leaves the annular space of the first stroke pipes located in the upper part of the pipe system, the steam enters the pipes of the same first stroke installed in the lower part of the pipe system and which are isolated from the remaining pipes in the volume limited by the casing 8 of one of the inclined partitions 11 , partitions 15 and 17. Between the casing 8 and the inclined partition 11 there is a gap through which the heating steam enters the pipes of the heat exchange surface of the first stroke of the heated water, and performing the function of surface air cooling Itel. (If it is necessary to increase the efficiency of the removal of non-condensable gases (air) under this section of the first-stroke pipes, a mixing-type air cooler can be provided, and the installation location of the horizontal perforated pipe 16 must be changed.) A horizontal air pipe 16 is installed behind these pipes, from which it is discharged through the pipe 18.

Condensate of heating steam flowing down from the pipes of the heat exchange surface of both the first and second strokes is “intercepted” by partitions 11 and, while maintaining “natural” subcooling, is directed to horizontal condensate collectors 12 in which corresponding openings are provided. The location and size of these holes in the condensate collectors is selected in such a way that a part of the pipes of the heat exchange surface located directly above the partitions is flooded 11. For this purpose, a flange 19 can be installed, which is installed in front of the hole in the condensate collector on the partitions 11.

When the condensate of the heating steam moves down the partitions 11, the condensate washes the flooded part of the pipes of the heat exchange surface and, upon contact with them, is additionally cooled. Twice supercooled condensate enters the condensate collectors interconnected by vertical drain channels 13. Condensate from the lower condensate collectors 12 is discharged by drain channels (pipes) 13, the lower open part of which is located below the normal level of condensate in the housing. (It is possible to drain supercooled condensate from each condensate collector with independent drain channels to the normal level of condensate in the housing.)

This allows you to prevent the condensate from heating with steam and remove it from the heat exchanger through the pipe 3 while maintaining the initial subcooling. Steam condensate from the mixing air cooler zone and from the second-stroke pipe zone located under the last inclined horizontal partition 11 flows to the condensate level in the casing 8, which practically coincides with the condensate level in the housing 1, and is discharged from the heat exchanger through the pipes 14 and 3. The nozzles 14 and the lower part of the casing are separated by a longitudinal vertical partition 15 along the entire length of the pipe system, the installation of this partition does not allow the flow of steam passing through the second-stroke pipe to enter the perforated exhaust pipe 16 and “steam” it.

Claims (1)

Steam-water heat exchanger, including a housing with steam inlet and condensate outlet pipes, a distribution water chamber with heated water inlet and outlet pipes, a pipe system with vertical partitions, straight or U-shaped tubes of the heat exchange surface, located in the casing, characterized in that between the vertical partitions inclined partitions are installed at an angle to the horizontal with condensate collectors in their lower part, and vertical drain channels connecting and between themselves and the bottom end of the drain channel connected to the bottom of the condensate is disposed below the condensate level in the housing.

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