RU2146227C1 - Heat and mass exchanger - Google Patents

Abstract

FIELD: heat power engineering; applicable in water heating with steam or superheated water with their direct contact. SUBSTANCE: heat and mass exchanger has body round in cross-section and end covers, water supply tangential branch pipes supplying. Supplying steam branch pipes may have nozzles and connected tangentially to body. Installed before steam nozzles are ejecting particles concentric to body and provided with upper and lower walls forming shell. Body may be made of several cylinders different in diameters. Steam branch pipes may be connected with cylinders of different diameters. Branch pipes supplying water may also be located in shells. EFFECT: higher efficiency of operation due to utilization of steam energy for increase of water pressure beyond the apparatus. 6 cl, 4 dwg

Description

 Known and found application are jet heat and mass exchangers in which water is heated when it is in direct contact with steam. Steam reaches sound speed, mixes with water, forming a homogeneous two-phase mixture. The energy of water and steam add up. Then the steam condenses. The water pressure at the outlet of the apparatus may be higher than the vapor pressure and the water pressure at the inlet to the apparatus.

 Such is the apparatus called the “Transsonic” (see Russian patent N 2016261).

 The disadvantage of this apparatus is the insufficient depth of regulation of the loads on the consumption of steam and water, especially at low vapor pressures. For example, heating water with steam in a heating system or hot water supply without using a mains pump is possible only in a very narrow range of loads. It does not have a large enough capacity, so several devices have to be installed on one heating system.

 A heat and mass transfer apparatus used as a centrifugal vortex deaerator is also known (see USSR author's certificate N 1134842 "Deaerator").

 This known apparatus has a cylindrical body with end caps, tangential nozzles for supplying a fluid and a heating medium (tangential nozzles) and a tangential nozzle for removing heated fluid.

 In this apparatus, the kinetic energy of the flow of water and steam (superheated heating water) are added. This allows you to partially restore the water pressure at the outlet of the apparatus, despite the fact that in the center of the body are the interface between the rotating flows of media (water and steam) and the zone of reduced pressure.

The disadvantage of this apparatus is that the steam leaving the nozzles enters a large volume space filled with water and instantly condenses without creating local overheating of a small volume of water to a temperature significantly higher than the average temperature of the water leaving the apparatus. The formation of a sufficient amount of a homogeneous two-phase mixture of water with steam does not occur. The formation of a “shock wave” (pressure jump) does not occur due to the transition of the sound barrier in a homogeneous two-phase mixture, as is observed in Transsonik devices. Therefore, the restoration of water pressure at the outlet of the apparatus is lower than that of Transsonika. However, the analogue allows you to heat a large amount of water at a large temperature difference. For example, in this apparatus, 250 t / h of water was heated from 16 to 108 ^o C, when 42 tons of steam per hour with a pressure of up to 1.5 ati were supplied through the apparatus. These characteristics do not possess direct-jet water heaters of the Transsonik type. When using steam with a pressure of 0.2 ati to heat water, the water pressure behind the apparatus was 0.6 ati.

 Another disadvantage of this apparatus is that the kinetic energy of the steam jet leaving the nozzles sharply decreases with a decrease in the steam flow rate, due to the fact that the flow rate is regulated immediately for all nozzles. There is no stepwise regulation of the steam flow rate due to the shutdown of part of the nozzles while maintaining the vapor pressure in front of the remaining nozzles.

 The closest in design and selected as a prototype is a deaeration column described in USSR author's certificate N 859313 "Vacuum deaeration installation".

 This known apparatus has a cylindrical casing with end caps with water and steam supply pipelines, steam and water supply nozzles connected tangentially to the casing, vertical ejection baffles located inside the casing, and a pipe for draining water from the casing.

 This apparatus can be used not only as a deaerator, but also as a water heater by direct contact with steam.

 The disadvantage of this apparatus is the low water pressure after the apparatus, which requires the installation of an additional pump to supply it to the consumer. The location of the ejection partitions not concentric with the body creates additional resistance to the flow of water and slows down the overall speed of rotation of the water, which reduces the kinetic energy of the water flow, which should go into the static water pressure when leaving the apparatus.

 The aim of the present invention is to increase the efficiency of the apparatus due to a more complete restoration of the water pressure behind the apparatus (for supplying water to other apparatuses or to backpressure pipelines without using a pump).

 For example, its use as a contact water heater for the heating network, in the event of failure of surface heaters, for preheating the water going to deaeration, use as low pressure heaters (HDPE) instead of bulky surface heaters at CHPPs, making it possible to use contact water heating of steam of reduced parameters, with sufficient water pressure and with sufficient restoration of water pressure after the apparatus.

 This goal is achieved by the fact that in the known heat and mass transfer apparatus having a cylindrical body with end caps, tangential nozzles (nozzles) for introducing water and steam, a nozzle for withdrawing heated water, inlet and outlet pipelines, ejecting vertical partitions separating the tangential nozzles (nozzles) ) from the main part of the tank volume, the ejection partitions are made concentric to the body and have upper and lower walls located perpendicular to the vertical with the formation of the casing, inside to torogo placed tangential nozzle for steam input.

 In addition, this goal is achieved that the body is made of cylinders (pipes) of various diameters. Steam and water nozzles are located on different horizontals and are attached to parts of the casing of different diameters, and if necessary, on the same horizontal, connected to each other, so that the steam outlet nozzle is installed first on the path of rotation of the media, followed by a water outlet.

 The conclusion of the vapor-supplying (tangential) nozzles in the casings, concentric to the casing wall and bounded on all sides by the walls, allows the steam to contact for a certain time with a small large amount of water and to overheat it significantly above the average temperature of the water leaving the apparatus, preventing microhydroshocks and minimizing cavitation destruction bodies in the vicinity of nozzles. It allows you to create a homogeneous two-phase mixture for a short time, provide a pressure jump and transfer maximum mechanical energy from steam to water (increase the rotation speed of the entire water flow, which ensures an increase in the water pressure at the outlet of the apparatus), and reduce resistance to the flow of rotating water.

 The conclusion of the tangential water supply nozzles (nozzles) in the casings, the installation of the steam outlet nozzle first (formerly the water outlet) on the medium rotation path prevents direct contact of the steam with the body (the steam is surrounded by water on all sides) and completely prevents cavitation destruction of the body. Installing a washer (annular partition) that separates the casing into the inlet and outlet compartments (the washer hole diameter being larger than the casing wall diameter, to the coaxial casing) allows the casing to be on one side of the liquid and gaseous (vapor) phases, become an ejector and eject water into the casing and give it a greater momentum of force (i.e. it is better to use the kinetic energy of steam to increase the speed of rotation of water, which in the future (with an increase in the radius of twist of water) will go into static energy th water pressure).

 In FIG. 1 shows a longitudinal section of a variant of a heat and mass exchanger, with steam and water supplied through tangential nozzles (nozzles) connected to the housing at the same radius, with a nozzle for additional supply of low-grade steam through one of the housing covers.

 In FIG. 2 is a cross-sectional view along AA in FIG. 1.

 In FIG. Figure 3 shows a longitudinal section of a variant of the apparatus, the housing of which is composed of several hollow cylinders (pipes) of different diameters, water supply pipes are connected to a part of a larger diameter housing, and steam supply to a part of a smaller diameter housing.

 In FIG. 4 is a cross-sectional view along AA in FIG. 3.

 The heat and mass exchanger has a hollow cylindrical body 1 of the same diameter (Fig. 1, 2) or composed of several hollow cylinders (pipes) - 1a, 1b, 1c (Fig. 3, 4), the upper end cover 2, and the lower 2a (in fact, the device does not has a top and bottom, it can also work upside down and in a horizontal position), an annular partition 3 (washer), an annular partition (washer) 4, dividing the inside of the case into the input and output compartments (installation of this washer is optional if the device is designed to work when fully filled casing with water (i.e. without phase separation of the flows inside the casing)), tangential nozzle for supplying water 5, which can be made in the form of a nozzle connected to a supply pipe, steam tangential nozzles 6 (and, if necessary) steam nozzles 6a, connected to the cover 2 and (or) 2a, the intermediate steam chamber 7 (see Fig. 1, 2. The chambers can be two, four, etc., the option with one annular chamber is possible) (nozzles 6 can also have independent steam supply to each with its own locking element, steam pipe 8, casing 9 having a wall, Proposition concentrically (coaxially) housing, - 9a and walls arranged perpendicular thereto, - 9b, a tangential outlet nozzle 10 attached to the outlet compartment of the housing.

 The operation of the apparatus is as follows.

 A variant of the apparatus of FIG. 1, 2. The vapor pressure in front of the apparatus is slightly greater than the water pressure. Heated water is supplied into the housing through all or part of the tangential nozzles 5 (by reducing the number of working nozzles (nozzles) 5, by closing the shut-off device on it, the high-speed water pressure can be significantly saved while reducing the load on the water). Water acquires a rotational movement and fills the entire volume of the body (with a small back pressure in the outlet pipe 10, a vertical rotating interface of media / phases / may appear). Steam is supplied through a steam line to nozzles 6 through chambers 7 or directly through a shut-off element. Steam crashes into a rotating stream of water, the pressure of which at the walls of the housing is maximum. With sufficient vapor pressure in front of the nozzle, the vapor velocity reaches sonic. In the collision of steam with water, he transfers to it his kinetic energy. Water begins to spin at a faster speed. The steam inside the volume limited by the casing 9 is mixed with water and a homogeneous two-phase mixture is formed, the compressibility of which is several times greater than the compressibility of steam or water separately. The speed of sound in a homogeneous mixture can drop below 20 m / s (whereas the speed of sound in water is 1500 m / s, in a pair - 500 m / s). The flow velocity can overcome the speed of sound and form a “shock wave” (pressure shock), as a result of which the vapor bubbles collapse and condense. (It is impossible to achieve a “shock wave” without installing covers). After the “shock wave”, a hydrodynamic regime is established in which a higher water temperature is obtained at the outlet of the casing than at the outlet of the apparatus and a higher water velocity than at the inlet. Further, warmer water is mixed with less heated water that has passed the casings, and the temperature of the water is equalized. The steam supply is controlled by the temperature of the water leaving the apparatus. If the heated water is cold and there is not enough high-pressure steam for the calculated heating of the water and backpressure of water at the outlet of the apparatus allows, an additional amount of steam can be supplied through the pipe 6a located in the lid of the apparatus. Moreover, the pressure of the steam supplied through the cover can be significantly lower than the water pressure at the outlet of the apparatus, since in a rotating stream of water the water pressure drops from the periphery to the center, and the speed increases, and vice versa, from the center to the periphery the pressure increases, and water speed drops. With sufficient back pressure of the water in the outlet pipe 10, water fills the entire volume of the housing, and with a small one, a vertical phase boundary is formed. With the formation of the phase boundary, the minimum thickness of the rotating layer of water determines the width of the washer 4.

 A variant of the apparatus of FIG. 3, 4. During the operation of this apparatus, the vapor pressure in front of it may be lower than the pressure of water. Water is supplied to the upper part of the housing 1b through tangential nozzles (nozzles), acquires rotational motion and moves from the periphery to the center, increasing and decreasing static pressure. Having overcome the washer 3, the rotating flow of water enters the housing part 1a. The water pressure on the walls of the housing 1a is lower than on the walls of the housing 1b due to the smaller radius of the swirl of water. Through the tangential nozzle 6 (in the drawing of Fig. 4, the second nozzle 6 with the nozzle is erroneously indicated by the number 5 (nozzles 5 did not fall into the section of Fig. 4), the steam crashes into the water stream. If the pressure difference at the inlet and outlet of the nozzles is critical or exceeds it then the steam velocity becomes equal to sonic. The casing 9 limits a certain amount of water that is overheated by steam. When a homogeneous two-phase mixture is formed, a “shock wave” and instant collapse of the vapor bubbles can form. The kinetic energy of the steam is transmitted by the rotating The flow rate of water increases. Overcoming the washer 4, the flow of water enters the outlet compartment of housing 1B and, rotating with an increase in the radius of twist, increases the pressure from the center to the periphery, while reducing the speed of rotation of the water. than the pressure in the nozzle 5. Friction occurs between the vertical layers of water (when one layer slides on the other.) Washer 3 helps to ensure that the lower layers of the liquid, rotating with greater speed, transmit a minimum of the energy of rotation of the upper them layers (in the housing 1b) due to sliding (due to the small contact area of the layers). This apparatus can operate with a significant counter-pressure of water in the pipe 10, at atmospheric pressure or near atmospheric pressure in the center of the apparatus. Therefore, it is possible to supply an additional amount of low-pressure steam (for example, with a pressure of 0.2 atm from the turbine bleed) through the central pipe 6a, or immediately through two pipes 6a and 6b attached to both (upper and lower) covers (pipe 6b in the drawing shown). Those. high-pressure steam should be used to accelerate the rotation of water (to ensure sufficient water pressure at the outlet of the apparatus to supply it to other units), and low-pressure steam - for additional heating of water.

 The implementation of the ejection partitions, separating part of the internal space of the casing, concentric to the casing and having upper and lower walls, and forming a casing in which the nozzles are placed, allows better use of the kinetic energy of the steam jet to increase the kinetic energy of the rotating water flow, increase the pressure at the outlet of the apparatus and transport heated water to units with backpressure in excess of steam pressure and water pressure in the supply pipe.

 The execution of the casing from cylinders (pipes) of different diameters, the connection to the casing of the tangential nozzle for supplying water to the upper part of the casing of a larger diameter, and the steam nozzles to the part of the casing of a smaller diameter, and at a lower level (height), allows steam with a smaller diameter to be supplied into the casing pressure than water and fully use the energy of steam to increase the kinetic energy of water (to restore the water pressure behind the apparatus). The presence of an annular partition (washer) between the levels of steam and water nozzles can reduce the transfer of energy from the lower rotating layers of liquid to the upper due to friction of the sliding layers of water and thereby reduce the back pressure of the rotating water flow on the casing wall at the level of the inlet tangential water pipe.

 The location of the water and steam nozzles inside the casing at the same level relative to the axis of the apparatus next to each other (the steam nozzle in front of the water in the direction of rotation of the water) prevents the ingress of steam (before mixing it with water) on the metal wall of the housing. This completely prevents cavitation destruction of the apparatus body.

 The presence of additional inlet steam pipes connected to the caps (to the upper or lower, or to two at once) allows the use of low-grade steam for heating water, with a pressure lower than the water pressure, without reducing the water pressure in the outlet pipe.

 The presence of an annular partition (washer) dividing the housing into the inlet and outlet compartments allows for a small back pressure of the water in the outlet pipe and the presence of a vertical phase boundary (in the form of a rotating cylinder) to have a minimum (not less than the width of the washer) layer of rotating water required to bubble steam through it. The presence of several steam nozzles (or groups of nozzles) having a separate inlet pipe with a shut-off element allows you to save the kinetic energy of the steam for transferring it to water under various loads (by disconnecting part of the nozzles and maintaining the vapor pressure in front of the others).

Claims (6)

 1. A heat and mass exchanger comprising a circular cross-section housing with end caps, supplying tangential water pipes, supply pipes and / or steam nozzles, which or part of which are connected to the housing tangentially (directly or through an intermediate chamber), a discharge pipe, ejecting partitions, separating part of the internal space of the body in front of the steam nozzles, characterized in that the ejection partitions are made concentric with the body, have upper and lower walls forming a casing, a concentric body sous.  2. The heat and mass exchanger according to claim 1, characterized in that the housing is made of several hollow cylinders of different diameters, and the tangential inlet pipes of water, the tangential inlet pipes (nozzles) of the pair are connected to parts of the housing of different diameters.  3. The heat and mass exchanger according to claim 1, characterized in that the mouths of the tangential water nozzles are placed in the same casings as the steam nozzles (nozzles), and the mouths of the tangential nozzles (nozzles) are located at the same level, perpendicular to the axis of the housing, so that the first a steam nozzle is installed along the rotation of the media, followed by a water nozzle (adjacent to it).  4. The heat and mass exchanger according to claim 1, characterized in that there are additional steam supply pipes connected to one or both covers and connected to the inside of the housing through openings (openings).  5. The heat and mass exchanger according to claim 1, characterized in that an annular partition (washer) is installed inside the housing at a level between the mouths of the inlet pipes (nozzles) of water and steam and the outlet pipe, separating the housing into the input and output compartments.  6. The heat and mass exchanger according to claim 1, characterized in that the individual steam nozzles or groups of nozzles have separate steam nozzles with regulating (disconnecting) bodies on them.

Images