RU122583U1 - FILM STEAMING MACHINE - Google Patents

Abstract

1. A film evaporator containing vertically installed heat exchange tubes fixed at the ends in the upper and lower tube sheets, a receiving and distribution chamber equipped with a branch pipe for supplying the initial solution, fixed from above on the upper tube sheet, adjacent to the upper ends of one compact part of the heat exchange tubes and designed for uniform distribution of the initial solution through these pipes and for the formation of a downward film flow of the solution on their inner surface, as well as an outlet chamber equipped with an outlet pipe, designed to remove the concentrated solution and the resulting secondary steam from the heat exchange pipes, adjacent to the upper ends of the rest of the compactly located heat exchange tubes and communicating them through the outlet pipe with a separator, in which the concentrated solution and the secondary steam are separated, characterized in that the lower ends of the heat exchange tubes adjacent to the outlet chamber are made They are elongated, brought out below the lower tube sheet, where they have holes in the walls and communicate with the lower ends of the pipes adjacent to the receiving and distribution chamber through the lower mortar chamber, which is sealed and attached to the bottom of the lower tube sheet. 2. The film evaporator according to claim 1, characterized in that the edges of the downwardly ejected heat exchange tubes adjacent to the outlet chamber are provided with teeth. Film evaporator according to claim 1, characterized in that the bottom of the lower mortar chamber under the pipes adjacent to the receiving and distribution chamber is made with a slope α = 10-60 ° to the horizontal

Description

The evaporation process is widely used to concentrate effluents of various industries in order to reduce their volumes and thereby reduce costs in the subsequent stages of processing and conditioning. This process is greatly complicated by pricing in cases where evaporated effluents contain surfactants. The need to combat pricing, causing losses of the processed product and contamination of the condensate of the generated secondary steam, determines the complexity of the concentration technology and design of the evaporators used. At the same time, the available publications indicate the possibility of evaporation of foaming solutions on combined film-type evaporators, which are a combination of devices with a falling film and devices with a rising film of an evaporated solution.

Known evaporator of this combined type, which is part of the patent of the Russian Federation No. 2039438, MKI A23C 1/12 "Multi-shell evaporator for food and evaporator". A General view of the known apparatus is presented in figure 2 in the description of this patent. The evaporator contains heat exchange tubes 22, vertically mounted in the heating chamber 15, fixed by the ends in the upper 19 and lower 20 tube sheets, the upper solution chamber 17, divided by a vertical partition 28 into two isolated chambers (cavities) 29 and 30. An isolated reception and distribution chamber 19 is intended to receive the initial solution supplied to the evaporation, contains a device 31 for introducing this solution and for its even distribution between part (half) of the heat transfer tubes 22, as well as for framing using a device 32 of the film flow of the solution down the inner surface of these tubes. The solution chamber 30 is adjacent to the second half of the heat exchange tubes and is designed to drain the concentrated solution and the secondary steam flowing from the upper ends of these tubes through the pipe 30 to the separator 16. In the separator 16, the concentrated solution and the secondary steam are separated. The concentrated solution is discharged through the nozzle 36 of the separator, and the secondary steam is discharged through the nozzle 37. The lower end of each of the tubes adjacent to the bottom of the receiving and distribution chamber 17, through an arcuate channel 41 communicates with the lower end of one of the heat transfer tubes adjacent to the outlet chamber 30 Thus, in a known evaporation apparatus, two heat-exchange chambers are formed: one with a falling film, the second with a rising film of the evaporated solution. During operation of the apparatus, the evaporated solution passes first from the top down the first chamber, in the form of a film enters the lower part of the second and, while maintaining the film flow, passes through the heat exchange tubes of the second chamber from the bottom up. In each chamber, the solution is evaporated due to the heat of steam condensing on the outer surface of the heat exchange tubes. The resulting secondary vapor is released from the solution film and moves along the central part of the heat exchange tubes unidirectionally with the film of the evaporated solution. Studies have shown that two heating (evaporation) chambers formed in a known evaporation apparatus that differ in the hydrodynamics of the evaporated solution (the first with the falling film of the evaporated solution, the second with the rising film of the evaporated solution), which work sequentially and together, significantly affect the mode and each other's work efficiency.

The advantages of this known combination evaporator are as follows.

Firstly, a more uniform distribution of the flow of the evaporated solution through the heat exchange tubes in the evaporating chamber with a rising film is ensured than is achieved in conventional evaporating apparatus with a rising film, operating separately. This allows you to get a more stable and efficient heat transfer and increase the productivity of the apparatus, preventing exposure of the heat exchange surface and the formation of deposits due to the uneven evaporation in the heat transfer tubes.

Secondly, with the adopted sequence of motion of the solution, the need for heating the solution in the lower part of the heat exchange tubes constituting the evaporation chamber with the rising film is eliminated to form a film flow of the solution up. In conventional evaporators with a rising film in the lower part of the heat exchange tubes, the solution heats up, then it boils and only then does the film movement with intense heat transfer form. At the same time, both heating and boiling -processes, low-intensity in heat transfer, determine the increased metal consumption and the cost of ordinary devices with a rising film.

According to the technical nature and the achieved positive effect, this known evaporator is closest to the claimed technical solution and therefore we have chosen as a prototype.

Considered known combination evaporator has the following disadvantages.

Firstly, the evaporator has a high resistance along the solution path, which is mainly due to the resistance to the movement of the vapor-liquid mixture in the arcuate channels connecting the lower ends of the heat exchange tubes with the falling and rising film of the solution. As a result, the speed of the secondary vapor and the speed of the film and, accordingly, the intensity of heat transfer in heat exchanging tubes with a rising film.

Secondly, as the published results of hydrodynamic studies have shown, when a vapor-liquid mixture moves in a connecting arc-shaped channels at a high speed, as well as in V-shaped heat-exchange tubes, a liquid can break off from the back surface of the connecting arc-shaped channel under the action of centrifugal forces, which excludes this part of the surface from the heat transfer process (see abstract 14 and 41 in the abstract. Journal of Chemistry, 1990). Due to the high speeds of the vapor-solution mixture, such a process can take place in certain operating conditions in the evaporator in question.

Thirdly, the need to place many arcuate tube channels (jumpers) between heat exchanging tubes with falling and rising films complicates the design of the known evaporator, increases its metal consumption and, consequently, the cost.

The aim of the creation of the proposed film evaporator is to eliminate these drawbacks and ensure conditions that achieve greater intensity of evaporation of the solution, thereby reducing the necessary heat transfer surface and simplifying the design of the apparatus.

This goal is achieved by the fact that in the film evaporator containing vertically mounted heat exchange pipes, fixed by the ends in the upper and lower tube sheets, a receiving and distribution chamber equipped with a nozzle for supplying the initial solution, mounted on top of the upper tube sheet, adjacent to the upper ends of one the compact part of the heat exchange pipes and designed for uniform distribution of the initial solution over these pipes with the formation of a film former on their inner the surface of the film flow of the solution downward, as well as the outlet chamber, equipped with an outlet pipe, designed to withdraw the concentrated solution and the resulting secondary steam from the heat exchange tubes, adjacent to the upper ends of the rest of the compactly located heat exchange tubes and communicating them through the outlet pipe with a separator , in which the separation of the concentrated solution and the secondary steam takes place, according to the invention, new is that the lower ends of the heat exchange tubes adjacent to the outlet chamber, are elongated and withdrawn below the lower tube plate and in communication with the lower ends of the tubes adjacent to the receiving-distribution chamber, through the lower solution chamber formed sealed and fixed to the lower bottom tube sheet.

In the inventive film evaporator apparatus, the edges of the downwardly exchanged heat exchange tubes adjacent to the outlet chamber can be provided with teeth, and their walls under the lower tube sheet can have openings. In the inventive film evaporator apparatus, the bottom of the lower solution chamber under the pipes adjacent to the reception and distribution chamber may have a slope of α = 10-60 ° horizontally to the boundary with the tube bundle adjacent to the outlet chamber, and the upper ends of the heat exchange tubes adjacent to the outlet chamber can be released upwards by ħ = 5-50 mm. In addition, in the inventive film evaporator apparatus into the wall of the lower solution chamber near the bundle of heat-exchange tubes adjacent to the outlet chamber, nozzles for supplying and leaving the solution can be cut, the number of heat-exchange tubes adjacent to the premix chamber may depend on the number of pipes adjacent to the outlet chamber, and these pipes may have different diameters.

The technical positive result from the practical implementation of the proposed film evaporator is to significantly reduce the pressure loss in the vapor-solution channel of the device by reducing the pressure loss of the secondary steam when it moves from the exit of the heat exchanger tubes with a falling film to the bottom of it entering the heat exchanger tubes with a rising film . This is achieved by reducing its speed while ensuring the smallest possible path of movement. In addition, the design of the inventive evaporation apparatus allows in each of the bundles of heat transfer tubes — with a falling or rising film of the solution — independently of the operation of the other, to establish the hydrodynamic regime most favorable for highly efficient concentration of the solution.

The analysis of scientific, technical and patent literature did not reveal patents and publications describing the designs of film evaporators and heat exchangers with the claimed combination of distinctive features, which allows us to conclude that the proposed technical solutions meet the criterion of "novelty", and their undoubted and significant advantages are that they meet the criterion "Significant differences."

The inventive film evaporation apparatus is illustrated by the following drawings: figure 1 shows a General view of the evaporation apparatus, figure 2 shows the lower part of the heat transfer tubes 1 and 2 of the evaporator and the lower solution chamber 15, which schematically shows the movement of the flows of the evaporated solution 20 and the secondary steam 17 from heat exchanging tubes 1 with a falling film to heat exchanging tubes 2 with a rising film, Fig. 3 - the lower part of the heat exchanging pipes and the lower solution chamber 15, in which under the heat exchangers are tubes 1 adjacent to the intake and distribution chamber 5, the bottom is made with a slope 16 to the heat exchange tubes 2 adjacent to the outlet chamber 9. FIG. 4 shows a view of the vapor space of the lower mortar chamber under the lower tube sheet 4 in section AA, as indicated in FIG. 2 , with a chart of the directions of the flow of the secondary vapor stream 17, FIG. 5 shows the lower solution chamber 15 with a slope 16, attached from the bottom to the lower tube sheet 4, as well as the lower ends 21 of the heat exchange tubes 2 with openings 24 brought into the lower solution chamber, and location pa tubes 25 and 26, which can be used to supply the solution and to withdraw part of the evaporated solution. Figure 6 shows a variant of the withdrawal of the ends 21 from the pipes 2 fixed in the plate 27, attached to the bottom of the lower tube sheet 4, and also shows the teeth 28 at these ends of the pipes. Figure 7 shows a variant of the structural implementation of the inventive evaporator, in which the upper ends 29 of the heat exchange tubes 2 are displayed above the upper tube sheet 3 to a height ħ. On Fig shows a General view of the inventive film evaporator, which used some of the considered distinctive structural elements.

Figure 1 shows a General view of the inventive evaporator containing vertically mounted heat exchange pipes 1 and 2, fixed with ends in the upper 3 and lower 4 tube sheets, a receiving and distribution chamber 5, equipped with a pipe 6 for supplying the initial solution, sent to the evaporation, fixed on top of the upper tube sheet 3, adjacent to the upper ends of one compact part of the heat transfer tubes 1 and intended for uniform distribution of the initial solution by the nozzle 7 over these pipes and for forming with the power of the film-forming device 8 on the inner surface of the heat-exchange pipes 1 of the film flow of the solution downward, as well as the outlet chamber 9, equipped with an outlet pipe 10, designed to output a concentrated solution and secondary steam coming from the upper ends of the heat-exchange pipes adjacent to it 2, through the outlet pipe 10 into the separator 11. In the separator 11, the concentrated solution and the secondary steam are separated. The concentrated solution is discharged from the separator through the pipe 12, the secondary steam through the pipe 13.

The inventive film evaporator operates as follows.

The initial solution enters the apparatus through the nozzle 6 into the receiving and distribution chamber 5 and the nozzle 7 attached to the inlet nozzle is evenly distributed over the film-forming device 8 located above the heat-exchange tubes 1 and forming a film-like flow of the solution along the inner surface of these tubes adjacent to the receiving distribution chamber 5. When flowing down in the form of a film, the solution is partially evaporated due to the heat of the heating steam entering the annulus of the apparatus through the nozzle 14. From the lower ends Of the heat exchange tubes 1, a partially concentrated solution in the form of a film 18 and the resulting secondary steam by streams 17 enter the lower solution chamber 15 (see FIG. 2). At the bottom of the lower solution chamber 15, flows of solution 20 are formed from the heat exchange tubes 1 to the heat exchange tubes 2 with elongated ends 21 and flow from below into these pipes. The streams of the secondary steam 17 from the pipes 1 are also directed to the pipes 2 and from below, or through the openings 22 in the elongated ends of these pipes, get inward and are directed upward through the pipes 2, entraining a solution penetrating into the pipes from below. At the same time, a solution film is formed in the near-wall layer of the heat exchange tubes, which is carried upward by the flows of the secondary vapor. To effectively form a solution film on the inner surface of the heat exchange tubes, holes 2 can be formed. It is preferable that the number of holes on each tube be at least 2, which are diametrically opposed to each other. In this case, counter flows of steam from these holes meet in the center of the pipes in the flow of the solution entering the pipes from below, and form a vapor cavity in the central part of the pipes, the steam from which rises upward, dragging the solution pushed to the walls. The level of the solution in the lower ends 21 of the heat exchange tubes 2 will be maintained at or about a little higher than the openings 22, which provides the described mechanism for film formation without significant resistance to the movement of steam flows 17. Rising in the form of a film upward, the solution finally evaporates due to the heat of the heating steam, condensing on the outer surface of the heat exchange tubes, and flows from the upper ends of the tubes 2 into the outlet chamber 9. The generated secondary steam 17 also rushes into this chamber (see FIG. 1 and FIG. 2). Streams of concentrated solution and secondary steam from the outlet chamber 9, flowing down the surface of the upper tube sheet 3, through the pipe 10 fall into the separator 11.

The drawings of figures 2, 3 and 4 clearly show that the movement of the secondary steam from the heat exchange tubes 1 with the falling film into the heat exchanging tubes 2 with the rising film occurs across the tube bundle between the heat exchanging pipes with the rising film 2 through a free passage, occupying the entire height vapor space in the lower solution chamber, which determines the speed of its movement, many times lower than the speed that occurs in arcuate channels in the evaporation apparatus adopted for the prototype, and therefore but less pressure loss during this movement. The reduction of steam losses during movement allows, with equal total losses of steam pressure in the apparatus, to increase the steam velocity and speed of the rising film in heat transfer tubes with rising film 2 in the inventive evaporator and, accordingly, to increase the evaporation rate not only in these pipes, but also in heat-exchange tubes with a falling film 1, i.e., in the entire claimed evaporator apparatus as a whole.

If necessary, the uniformity of the flow of solution from the bottom of the solution chamber from the bottom into the heat exchanger pipes adjacent to the outlet chamber can be improved by providing the edges of the downward heat exchanger tubes 21 with teeth, as shown in Fig.6.

To reduce the time of overflow of the evaporated solution from heat exchanging pipes with a falling film 1 to heat exchanging pipes with a rising film 2 and to increase the flow rate of the solution at the inlet to the heat exchanging pipes with a rising film 2, the bottom of the lower solution chamber under the pipes 1 adjacent to the reception and distribution chamber can be performed with a slope of α = 10-60 ° horizontally in the direction of the tube bundle 2 with the rising film to the border with the bundle of these tubes. (see figure 3).

To prevent possible inhibitory effect of the layer of concentrated solution formed on the upper tube sheet 3 when it flows from it from the outlet chamber 9, the upper ends of the heat exchange tubes 2 adjacent to the outlet chamber can be released upward (protrusion 16, see Fig. 7) ħ = 5-50 mm above the upper surface of the upper tube sheet 3.

To improve the convenience of starting up the inventive evaporator apparatus to work, as well as to enable separate regulation of the flows of the evaporated solution through heat exchange tubes with a falling film 1 and a rising film 2, they can be cut into the wall of the lower solution chamber near the tube bundle adjacent to the outlet chamber nozzles for supplying 25 and output 26 of the evaporated solution (see Fig. 8).

To ensure the possibility of providing the most independent of independent hydrodynamic and thermokinetic operating conditions, the heat transfer pipes adjacent to the receiving and distribution and outlet chambers can be made of different diameters and vary in quantity.

The design of the lower ends of the heat exchanger tubes adjacent to the exhaust chamber in the inventive film evaporator provides rapid almost instantaneous formation of a film of the evaporated solution in the downwardly directed part of the heat exchanger pipe with a rising film, in which the jets of the incoming secondary steam initiate a steam cavity below the heated section and rush immediately form at the entrance to the heated section near the walls its film of the evaporated solution, which has a high speed and intensively mixing chained that ensures intensive heat transfer across the heat exchange pipe and prevents the formation of salt deposits at the bottom of it, which takes place in the operating evaporators with a rising film.

The possibility of independent changes in the diameters and number of heat exchanging pipes with a falling and rising film allows us to create hydrodynamic conditions in these pipes that are most favorable for efficient heat transfer and continuous operation both with one and the other mutual movement of the interacting phases, preventing the negative effects characteristic of the evaporation apparatus - prototype.

Thus, the practical implementation of the claimed design of the film evaporator allows not only to significantly increase the heat transfer intensity and, therefore, to reduce the dimensions or increase productivity, ceteris paribus, compared with the known evaporators of this type, but also to create the conditions of hydrodynamics and heat transfer, the most favorable for the process of evaporation of the solution both in heat exchanging tubes with a falling film, and when it moves in the form of a rising film. In addition, when using the inventive apparatus more reliably ensures the stability of its operation and ease of operation of the technological installation, which will be used in the apparatus.

Claims (7)

1. A film evaporator comprising vertically mounted heat exchange tubes fixed with ends in the upper and lower tube sheets, a receiving and distribution chamber equipped with a nozzle for supplying an initial solution, mounted on top of the upper tube sheet, adjacent to the upper ends of one compact part of the heat transfer pipes and designed for uniform distribution of the initial solution over these pipes and for the formation of a film flow of the solution downward on their inner surface, as well as the outlet to amer, equipped with an outlet pipe, designed to withdraw the concentrated solution and the resulting secondary steam from the heat exchange tubes, adjacent to the upper ends of the rest of the compactly located heat exchange tubes and communicating them through the outlet pipe with a separator in which the concentrated solution and the secondary steam are separated, characterized in that the lower ends of the heat exchange pipes adjacent to the outlet chamber are elongated, brought out below the lower tube sheet, where in the walls they have tverstiya and communicate with the lower ends of the tubes adjacent to the receiving-distribution chamber, through the lower solution chamber formed sealed and attached to the lower bottom tube sheet. 2. The film evaporator according to claim 1, characterized in that the edges of the downwardly heat-exchanging tubes adjacent to the outlet chamber are provided with teeth. 3. The film evaporator according to claim 1, characterized in that the bottom of the lower solution chamber under the pipes adjacent to the receiving and distribution chamber is made with a slope of α = 10-60 ° horizontally to the boundary with the tube bundle adjacent to the outlet chamber. 4. The film evaporator according to claim 1, characterized in that the upper ends of the heat exchange tubes adjacent to the outlet chamber are released upward by ħ = 5-50 mm. 5. The film evaporation apparatus according to claim 1, characterized in that the nozzles for supplying and discharging the solution are cut into the wall of the lower solution chamber near the tube bundle adjacent to the outlet chamber. 6. The film evaporator according to claim 1, characterized in that the heat exchange tubes adjacent to the receiving and distribution and outlet chambers have different diameters. 7. The film evaporator according to claim 1, characterized in that it has different amounts of heat transfer tubes adjacent to the receiving and distribution and outlet chambers.