RU48045U1 - HEAT EXCHANGE VERTICAL HOUSING AND TUBE UNIT - Google Patents

Abstract

The utility model relates to heat exchangers and can be used in the aluminum and chemical industries, as well as in the power industry.

The device comprises a vertical housing with a built-in heat exchanger in the form of a tube bundle of pressure and pressure pipes fixed in tube sheets, a lower solution chamber with a distribution grid and an upper separation chamber with a means for returning particles of the cleaning medium. The latter is fixed at the end of the outlet pipe of the separation chamber and is made in the form of a shelf cascade sump with multi-tiered flat shelves. In this case, the lower ends of the downpipes of the downward flow of the technological solution are bent from the vertical by 60-120 degrees, and the edge of their ends has a bevel with an angle of up to 30 degrees from the vertical with the angle opening in the direction of upward flow.

Description

The utility model relates to heat exchangers, for example, to heaters of technological solutions and can be used in the aluminum and chemical industries, as well as in the power system.

It is widely known in various branches of technology to process a large number of solutions containing scale-forming impurities that precipitate when the solutions are heated on the heat transfer surfaces of heat exchangers and lead to a decrease in their thermal conductivity. The decrease in the operational efficiency of such devices necessitated their periodic shutdowns for cleaning and washing, which leads to downtime of technological equipment and additional costs for its maintenance.

Known heat transfer vertical shell-and-tube apparatus [patent No. DE 3818819, CL. F 28 D 1/02, publ. 12/14/1989], comprising a housing with lower and upper mortar chambers, with nozzles for input and output of the solution in the housing covers and a heat exchange chamber between them. The latter is formed by a tube bundle of pressure and downpipes fixed in fixed tube sheets and has coolant inlet and outlet pipes in the annulus. A distribution grid is mounted in the lower solution chamber.

A feature of the known apparatus is that to prevent the formation of deposits or corrosion on the heat exchange surface of the pipes, it provides for the introduction of a cleaning abrasive medium into the flow of the technological solution. For its closed circulation through pressure and downpipes and the exclusion of its removal through the outlet pipe of the solution, the walls of the upper chamber are made in the form of a diffuser, and the lower ends of the downpipes are constricted in the form of chokes. With a gradual expansion of the flow in the diffuser, the kinetic energy of particles of a different process density and a denser cleaning medium decreases with their separation into fractions. As a result, the particles of the cleaning medium descend down

downpipes with a non-pressure flow, additionally losing energy in the throttle, enter the distribution chamber, where they are again picked up by the upward flow of the solution.

The disadvantage of this device is that in transient modes of operation of the apparatus due to local eddies associated with separation of the flow from the walls and the redistribution of velocities along the flow cross section in the upper solution chamber, particles of fine-grained material from the cleaning medium are removed together with the solution, thereby reducing the efficiency of the device .

A similar and closest to the claimed device known heat exchanger [US patent No. 4427053, CL. F 28 D 13/00, dated 24.06.1984] vertical shell and tube. The heat exchanger also contains a housing with a diffuser of the upper solution chamber, a tube bundle in the tube sheets, which together with the supply and removal pipes of the heat carrier form a heat exchange chamber, a distribution grid in the lower solution chamber and solution inlet and outlet pipes in the housing covers (the device is taken as a prototype).

In contrast to the above-mentioned feature of this device is that, to improve the process of separating the particles of the cleaning medium from the heated solution, at the base of the diffuser of the upper solution chamber, there are ring-shaped reflector screens with annular gaps designed to suppress the energy of the particles of the cleaning medium and to prevent their removal to flow of a heated solution. For the circulation of the cleaning medium, one axial lowering pipe with a cross section exceeding the cross section of the pressure pipe is provided. In this case, the cutoff of the lower end of the lowering pipe is placed below the cutoff of the ends of the pressure pipes so that the particles falling into the zone of the lower solution chamber directly above the separation grid are again picked up by the upward flow of the solution and together with it fall into the pressure pipes, having an abrasive effect on the heat exchange surfaces.

However, the restriction of the height of the separation zone by the reflector screen in comparison with the above device creates additional resistance to the upward flow of the solution in the pressure pipes. The solution rises from under the reflector screen only in circular flows around the periphery and in the center of the tube bundle. As a result, under the reflector screen in the pressure pipes a backwater is created that reduces the speed of movement in them

upward flow of the suspension and, accordingly, the effect of suspended particles of the cleaning medium on the inner walls of these pipes. At the same time, the presence of a central hole in the reflector screen reduces the driving force for moving the flow in the downpipe and significantly slows down the more concentrated suspension in it, reducing the efficiency of the organized circulation of the suspension through the tube bundle and the operation of the apparatus as a whole.

These shortcomings stimulated the search for new technical solutions.

The proposed device is aimed at solving the problem of eliminating the formation of deposits and reducing the influence of thermal resistance of contamination of heat transfer surfaces on the efficiency of the heat transfer process by maintaining a constant concentration of particles of cleaning abrasive material in the recirculation loop of the continuous pipe cleaning system.

The technical result is achieved by the fact that in a vertical heat-exchange shell-and-tube apparatus containing a housing, a tube bundle of pressure pipes of the upward flow of the process solution and the down pipes of the downward flow of the cleaning medium to prevent suspended solids on the inner walls of the pipes, the lower solution a chamber with a distribution grid, an upper separation chamber with a means for returning / circulating particles of the cleaning medium and inlet pipes the solution outlet, the inlet and the outlet of the coolant, according to the utility model, the means for returning the cleaning medium is made in the form of a shelving cascade sump with multi-tiered flat shelves, the sump is fixed at the end of the outlet pipe, while the lower ends of the downflow pipes are located between the pipe and distribution grids of the lower mortar chamber, bent from the vertical by 60-120 degrees, and the cutting of their ends is made with a bevel at an angle of not more than 30 degrees from the vertical with the opening angle in the direction of sunrise a clear solution flow.

The technical result is that the sump installed on the outlet pipe frees up the space of the upper solution chamber for the upward flow of the heated solution, while ensuring the separation of the particles of the cleaning medium both along the height of the chamber and directly in the sump itself. In other words, installing a sump in the upper elevation of the chamber allows you to organize two stages of separation, which in combination with its implementation

with multi-tiered flat shelves it is possible to practically provide a closed recirculation loop without loss of a cleaning medium in a continuous pipe cleaning system. In turn, the lower ends of the downpipes bent from the vertical by 60-120 degrees, in combination with their end cut off at an angle of up to 30 degrees, can eliminate the critical state of the system (flooding mode) that occurs at the lower end of the pipe as a result of the oncoming flow and contribute to the downward flow the movement of the suspension in these pipes by lowering the pressure at the beveled ends when they flow around them in an upward flow.

From the analysis of scientific, technical and patent literature of the claimed combination of features is not revealed, which allows us to conclude that the claimed technical solution meets the criterion of "novelty."

An example of a specific implementation of the proposed device is illustrated in the drawing, where in FIG. a schematic sectional view of a heat exchanger. The heat exchanger consists of a heat exchange chamber 1 in the form of a tube bundle of pressure 2 and lower 3 pipes mounted in tube sheets 4 in a cylindrical casing-casing 5, the lower receiving solution chamber 6 with a distribution grid 7 and the upper outlet separation chamber 8. Chambers 6, 8 formed by the lower and upper covers 9, 10 of the casing-housing 5. The bottom cover 9 is provided with a supply pipe 11 of the technological solution, and the top cover 10 is equipped with a discharge pipe 12, at the lower end of which a separation shelf multilevel compartment is mounted Toynik 13 with a package of flat shelves 14.

The device operates as follows. The technological solution, prone to the formation of deposits, for example, bauxite pulp is fed through the inlet pipe 11 into the lower solution chamber, passes through the distribution grid 7, rising, brings to the fluidized state the fine-grained material of the cleaning medium and flows upstream into the pressure pipes 2, where suspended grains have an abrasive effect on their inner walls. At the same time, the technological solution is subjected to heat treatment by the flow of coolant flowing in the annular cavity of the heat exchange chamber 1 through the nozzles 15, 16. Having passed the vertical pressure pipes 2, the heated technological solution enters the upper solution separation chamber, where, rising, it loses part of the settling particles of the cleaning medium along the way . IN

settler 13 enters a process solution that has already partially freed from the cleaning medium, where the rest of the particles settle on the tiers of the flat shelves 14, which settle down in a consolidated stream. Due to some rarefaction in the lowering pipes due to the bent and chamfered edges of their lower ends 17, the mass of the cleaning medium flows through them into the lower solution chamber with a non-pressure stream, where it is again picked up by the upward flow of bauxite pulp. At the same time, a closed recirculation system is provided, and due to the practically elimination of losses, an increased degree of conservation of the concentration of the cleaning medium in the technological solution is achieved.

Sources of information:

1. German patent No. DE 3818819, Cl. F 28 D 1/02, publ. 12/14/1989.

2. US Patent No. 4427053, Cl. F 28 D 13/00, publ. 01/24/1984. (prototype).

Claims (1)

A vertical heat-exchange shell-and-tube apparatus comprising a housing integrated in it and secured in a tube sheet tube bundle of pressure pipes of the upward flow of the process solution and downflow pipes of the downward flow of the cleaning medium to prevent suspended sediment deposits on the inner walls of the pipes, lower solution chamber with distribution grid, upper separation a chamber with means for returning / circulating the particles of the cleaning medium and nozzles for the inlet, outlet of the solution, inlet and outlet of the coolant, characterized in that the means for returning the cleaning medium is made in the form of a shelving cascade sump with multi-tiered flat shelves, the sump is fixed at the end of the outlet pipe, while the lower ends of the downflow pipes, located between the pipe and distribution grids of the lower mortar chamber, are bent 60 from the vertical -120 °, and the cutting of their ends is made with a bevel at an angle of not more than 30 ° from the vertical with the opening of the angle in the direction of upward movement.