RU220402U1 - Spiral heat exchanger - Google Patents

Abstract

The utility model relates to the field of heat engineering and can be used in heat and mass transfer devices. The spiral heat exchanger contains a housing, covers, supply and exhaust pipes, two spiral tapes twisted into a roll, segment partitions made in the form of strips, evenly distributed along the length of each spiral tape and installed in a checkerboard pattern to form a gap to one of the covers, at a distance of from each other, defined by the expression:

V=l/0.8÷0.9 ,

where B is the distance between the slats, equal to the width of the spiral tape, m;

l – length of the bar, m,

and the beginnings of the spiral tapes are fixed to the opposite ends of the partition installed in the center of the heat exchanger. The technical result is an increase in the efficiency of the heat exchange process.

Description

The utility model relates to the designs of heat and mass transfer devices, namely spiral heat exchangers, and can find application in the chemical, petrochemical, oil refining, gas, food, pharmaceutical, engineering, energy, nuclear and other industries, as well as in environmental processes of wastewater treatment and flue gases.

A spiral heat exchanger is known, which consists of two spiral channels wound from rolled material around a central dividing partition (root) and closed at the ends with lids. Both channels are either welded to seal at both ends, or installed on removable covers with gaskets. To give the channels of spiral heat exchangers a constant cross-section and the required rigidity, pins are welded to one of the tapes before winding, which increase rigidity and fix the distance between the channels [Equipment for oil refining, chemical and petrochemical industries / Under the general editorship of A. S. Timonin / 2nd edition, reworked corr. and additional – Moscow: Vologda, Infra – Engineering, 2022, p. 498 - 500].

The reasons preventing the achievement of a given technical result include insufficient productivity due to the constant speed of coolant movement in both channels. This leads to a decrease in the rates of heat transfer and heat transfer through the surfaces of the rolled material.

There are known designs of spiral heat exchangers for liquids, consisting of a spiral housing with dead-end channels, two flat covers at the ends with gaskets, four fittings for the inlet and outlet of coolants, two of which are installed in the central part of the cover, and two in the upper part of the housing on the manifolds. The spiral body is made on feet when installed on the foundation in a horizontal position. Or the housing is made on axles for installation in any position: vertical, horizontal or inclined [Plate and spiral heat exchangers / N.V. Baranovsky, L.M. Kovalenko, A.R. Yastrebenetsky. - Moscow: Mechanical Engineering, 1973. - 288 p.].

The reasons preventing the achievement of a given technical result include insufficient productivity due to relatively low heat transfer and heat transfer coefficients at average constant flow rates of both coolants along the surface of the housing spirals. In addition, the absence of restrictive elements between the walls of the channels at elevated pressures can lead to deformation and collapse of the surfaces of the spiral along their length and width, which will require stopping and repairing the spiral heat exchanger, and therefore will lead to a decrease in operating time and productivity in general.

A known spiral heat exchanger contains channels for working media made of rolled tape, one of which contains pins equipped with turbulators made of tape twisted in the longitudinal direction [RF Patent No. 2156423, IPC F28D 7/04; September 20, 2000].

The reasons preventing the achievement of a given technical result include the complexity of the design, low-tech manufacturing of the heat exchanger, as well as increased weight due to the presence of complex sealing units, which determines the high cost of manufacturing.

The closest technical solution in terms of the set of characteristics to the claimed object and adopted as a prototype is a spiral heat exchanger containing a housing with inlet and outlet pipes, a two-channel spiral made of sheets, parts that fix the distance between the sheets of the spiral, stops placed in channels on both sides of the spiral, a seal ends of the spiral, covers with gaskets at the ends of the spiral, and the parts fixing the distance between the sheets of the spiral are made in the form of zigzag spacers placed along the entire spiral [RF Patent No. 74697, IPC F28D 7/04; 01/28/2008].

The reasons preventing the achievement of a given technical result include low productivity due to the variability of the speed of both coolants along both surfaces of a two-channel spiral made of sheets in the housing, which leads to a decrease in the overall heat transfer coefficient, and hence a decrease in productivity.

The technical result of the proposed design of the mass transfer column is to increase the efficiency of the heat transfer process.

The stated technical result is achieved by the fact that a spiral heat exchanger containing a housing, covers, supply and outlet pipes, two spiral tapes twisted into a roll, segment partitions, characterized in that the segment partitions are made in the form of strips evenly distributed along the length of each spiral tape and installed in a checkerboard pattern with the formation of a gap to one of the covers at a distance from each other determined by the expression:

V=l/0.8÷0.9 ,

where B is the distance between the slats, equal to the width of the spiral tape, m,

l – length of the bar, m,

and the beginnings of the spiral tapes are fixed to the opposite ends of the partition installed in the center of the heat exchanger.

Segment partitions, made in the form of strips and resting against the walls of another spiral tape, fixing the spiral gap, increase the rigidity of the surface of the spiral tapes and do not allow the tapes to wrinkle and deform under the pressure of coolants. This increases the mileage between repairs, which means it helps to increase the main operating time of the device and its productivity.

Installation of segment partitions at a distance between them equal to the width of the spiral tape, as well as in a checkerboard pattern with the formation of a gap to one of the covers, leads to the absence of stagnant zones and promotes the movement of coolants from longitudinal to transverse, but with an equal average speed. This periodic movement ensures equalization of the residence time of all flow elements inside each channel (with ideal mixing between adjacent slats and ideal displacement from inlet to outlet of each coolant). This transition to the ideal displacement of the flow structure of each coolant increases the rate of heat transfer, and therefore contributes to an increase in the efficiency of the heat transfer process.

Also, the installation of segment partitions with the formation of a gap to one of the covers ensures a rotation of the flow of each coolant by 180° in these gaps. Such a change in the direction of coolant flow from one cell between adjacent segmental partitions to another transfers the movement of coolants to the ideal displacement mode, which contributes to an increase in heat transfer and the efficiency of the heat exchange process.

Reducing the relative length of each segment partition, compared to the claimed value of 0.8, does not allow the positive effect of changing the direction of coolant flow by 180° to be fully used. This reduces the transition to ideal displacement of the entire mass of each coolant and reduces the efficiency of the heat exchange process.

An increase in the relative length of each segment partition, compared with the claimed value of 0.9, significantly increases the hydraulic resistance, which reduces the average speed of the coolants. This leads to a decrease in heat transfer. Typically, the same segmental partitions are placed in the inter-tube space of shell-and-tube heat exchangers to change the longitudinal movement of the coolant in this inter-tube space to the transverse one, which also increases heat transfer and the efficiency of the heat exchange process.

In fig. 1 shows a general view of the proposed design of a spiral heat exchanger; Fig. Figure 2 shows a cross section of a spiral heat exchanger.

The spiral heat exchanger consists of a housing 1, covers 2, supply pipes 3 and outlet 4. Inside the housing 1 there are two spiral tapes 5 twisted into a roll, the beginnings of which are fixed to the opposite ends of the partition 6. As a result, two spirals are formed with an offset of 180° and two sealed and cavities isolated from each other (spiral channels).

On each spiral tape 5, on one side, there are evenly distributed along the length of the segment partition 7, made in the form of strips and installed in a checkerboard pattern to form a gap to one of the covers. In this case, when twisting the spiral tapes 5, the segment partitions 7 rest against the walls of another spiral tape 5, thus fixing the spiral gap.

The spiral heat exchanger of the proposed design operates as follows.

Housing 1 is hermetically sealed with covers 2 using bolts, nuts and gaskets. Through supply pipes 3, coolants are supplied countercurrently into the spiral heat exchanger; each coolant enters through its own spiral channel formed by spiral tapes 5, and also, without mixing, is discharged through its outlet pipes 4 to the outside. Inside the spiral channels, each coolant does not move along the heat transfer surface of the spiral tapes 5, but across it, passing between the segment partitions 7. At the same time, the direction of each coolant flow between the segment partitions 7 changes, forming vortex flows due to different values of the fictitious speed, thereby increasing the fictitious flow speed in the area of their installation, which will allow destruction of the wall laminar layer on both sides of the spiral channel. That is, there is a transition to ideal displacement, due to the absence of stagnant zones, which means the efficiency of the heat transfer process increases.

Thus, the use of a spiral heat exchanger containing a housing, covers, supply and outlet pipes, a partition, two spiral tapes twisted into a roll with segmented partitions evenly distributed along their length and installed in a checkerboard pattern with the formation of a gap to one of the covers allows to increase efficiency heat transfer process.

Claims (5)

A spiral heat exchanger containing a housing, covers, supply and outlet pipes, two spiral tapes twisted into a roll, segment partitions, characterized in that the segment partitions are made in the form of strips evenly distributed along the length of each spiral tape and installed in a checkerboard pattern to form a gap to one of the covers at a distance from each other determined by the expression: V=l / 0.8÷0.9 , where B is the distance between the slats, equal to the width of the spiral tape, m, l – length of the bar, m, and the beginnings of the spiral tapes are fixed to the opposite ends of the partition installed in the center of the heat exchanger.

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