RU34095U1 - Evaporator for crystallizing and scale-forming solutions - Google Patents

Description

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MPKVOSH1 / 12

Evaporating apparatus for crystallizable and scale forming

The utility model relates to evaporation technology. It can be used in the construction of evaporators designed for evaporation of solutions, from which crystallizing and scale-forming salts are released, operating in such a mode when the evaporated solution circulates through heat exchange tubes.

When evaporating crystallizing and scale-forming solutions, part of the solvent, water, is removed from the solution. As a result of this, crystallizing salt precipitates from the solution. In this case, the uniformity of the distribution of the solution circulating in the evaporator through the tubes of the tubular heater plays the most important role. At the same time, for most evaporators, especially for devices with large diameter tubular heaters with a large number of tubes, it is not possible to achieve uniform distribution of the solution through the tubes. As tests of evaporators have shown, in one tube of the tubular heater the solution goes up at a considerable speed, in the other it is motionless, and in the third it even goes down. The consequence of this uneven distribution of the solution in the tubes is the overgrowth of the inner surface and the subsequent clogging of the tubes with crystallizing salt. As a result, the productivity of the apparatus decreases and it has to be washed with water, which must be evaporated, which requires additional steam costs. In the case of a uniform distribution of the solution through the tubes, their overgrowing and clogging is significantly reduced. This leads to an increase in productivity, an increase in the duration of the inter-flushing cycle, a decrease in the amount of water introduced to flush the apparatus and, consequently, the cost of steam for its evaporation.

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Known evaporator with natural circulation with an external tubular heating chamber (see Kasatkin A.G. Basic processes and apparatuses of chemical technology. -M .: Chemistry, 1971. -p. 388-389). The apparatus consists of a separator, a remote tubular heating chamber, inlet and outlet solution chambers connected to it, and a circulation pipe connected to the inlet solution chamber. Moreover, in the inlet solution chamber there is a device for distributing the solution flow through the pipes of the heating chamber, made in the form of several guide plates located on a bend from the pipe into the inlet chamber and bent along the turning radius.

This apparatus is used to evaporate crystallizing and scale-forming solutions.

A disadvantage of the known apparatus is the insufficient evaporation efficiency due to the low heat transfer intensity, rapid overgrowing and clogging of the tubes with crystallizing salt. As a result, the apparatus has to be washed, and the washing water evaporated, spending an additional steam. The reason for the noted shortcomings is the inefficiency of the distribution device in the input chamber of the known apparatus, which does not ensure uniform distribution of the solution flow through the pipes of the heating chamber, which leads to overgrowing and clogging of the tubes, reducing the intensity of the apparatus and the productivity of the apparatus.

A known evaporator (see the evaporator of the company "Speyshim, drawing. No. 0981123, Voskresensk PO" Phosphorite, 1968), containing a tubular heater with connected inlet and outlet solution chambers, a separator connected to the heater through a boiling pipe and circulation pipes, a pump and a device to prevent deposits of crystals in the pipes of the heater, made in the form of a perforated lattice installed in the circulation pipe.

A disadvantage of the known apparatus is the quick clogging of the pipes of the tubular heater and a decrease in the intensity of operation and productivity of the apparatus. Applied device for

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preventing deposits in the form of a perforated grating installed in the circulation pipe does not provide an even distribution of the solution through the tubes, which leads to their overgrowing.

Closest to the claimed technical essence is an evaporator for crystallizing and scale-forming solutions according to ed. testimonial. USSR. No. 719648 IPC BO1D 1/12, 1980, containing a tubular heater having an inlet and outlet solution chambers, a separator connected to the heater by means of a boiling pipe and a circulation pipe, a pump and a device for preventing crystal deposits in the heater pipes, installed in the inlet mortar chamber and made in the form of vertical plates intersecting each other with the formation of cells for the passage of the solution with a distance between the plates equal to (0.5 - 1) the diameter of the heater tubes with the height of the plates is (0.15 - 15) the distance between the plates. This device is taken as a prototype.

This device allows you to evaporate crystallizing and scale-forming solutions with a sufficiently high intensity and performance. At the same time, the device in the known apparatus for preventing the deposition of crystals in the heater tubes, installed in the inlet solution chamber, captures large pieces and growths of salt crystals and does not allow them to get into the tubes and clog them.

A disadvantage of the known apparatus is the uneven flow of the solution through the tubes of the tubular heater. As a result, deposits of salts released from the solution during evaporation appear in tubes with a downward flow of the solution and the stagnant zone. These tubes overgrow and clog at an accelerated pace. The heat load on the remaining tubes increases and a more intensive release of crystalline soda occurs in them, which, in turn, causes them to overgrow and clog. As a result, the intensity of the work and the productivity of the apparatus are reduced.

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pieces of salt. As a result, the hydraulic resistance of the apparatus increases, the flow rate of the solution circulating through the tubular heater decreases, and the uneven distribution of the solution through the tubes increases. All this leads to a decrease in the intensity of work and productivity of the device, leads to an increase in energy consumption.

In addition, a disadvantage of the known apparatus is the high cost of electricity consumed for the operation of the circulation pump.

The proposed apparatus for crystallizing and scale-forming solutions is deprived of these drawbacks, during operation of which the desired technical result will be achieved - uniform distribution of the solution through the tubes and, therefore, increased intensity, productivity, as well as increased reliability and reduced energy costs.

The inventive apparatus, as well as the prototype apparatus, comprises a tubular heater with upper and lower tube boards, an inlet (lower) and outlet (upper) mortar chambers, a separator connected to the heater by means of a boiling pipe and a circulation pipe, and a device for preventing crystal deposits in the pipes a heater installed in the inlet (lower) mortar chamber. The inventive apparatus differs from the prototype in that the device for preventing deposits is made in the form of a shell having the shape of a reverse truncated cone and placed coaxially with the inlet solution chamber. The inventive apparatus also differs in that coaxially to the shell is placed at least one more shell in the form of a reverse truncated cone. The difference of the claimed apparatus also lies in the fact that the upper edge of the device for preventing deposits is placed at a distance (0.3 - 0.7) of the diameter of the tubular heater from the lower tube plate. The lower edges of the shells can be placed in the same plane. In addition, the height of the shell can optimally be (0.5 - 1.5) the difference between the diameters of the heater and the circulation pipe. Another difference of the claimed apparatus is that the height of the inner shell is greater than or equal to the height of the outer. Besides

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Moreover, the claimed apparatus is characterized in that the solid angle of the inner shell is less than the solid angle of the outer. Along with the foregoing, the claimed apparatus is characterized in that the shell is provided with a cylindrical part located in the output part of the circulation pipe, or each of the shells can be equipped with a cylindrical part located in the output part of the circulation pipe.

The inventive apparatus meets all the criteria of patentability. It is new, because from the technology department no solutions with the same set of essential features are known, as evidenced by

the above analysis of the analogues of the claimed technical solution.

The inventive apparatus is industrially applicable and can be used in

various industries in evaporation plants. All signs included in the aggregate of essential, feasible and reproducible and, to achieve the expected technical result, are used in full.

The following is a description of the specific implementation of the claimed

apparatus - confirmation of this.

The figure 1 shows the design of the inventive apparatus, and the figure 2

device design to prevent deposits of crystals in the tubes.

The evaporator for crystallizing and scale-forming solutions contains a tubular heater 1 with an upper 2 and lower 3 tube boards, an inlet (lower) 4 and an outlet (upper) 5 solution chambers, a separator 6 connected to the heater 1 through a boiling pipe 7 and a circulation pipe 8 and a device 9 for preventing deposits of crystals in the pipes of the heater 1, installed in the input (lower) mortar chamber 4 and made in the form of a shell 10 having the shape of a reverse (inverted) truncated cone and placed coaxial input solution chamber 4. The device 9 is mounted in the input solution chamber 4 with one of the known methods, for example by means of welded gussets.

A device 9 for preventing deposits of crystals in the heater tubes (key 9 in figure 1) is shown in figure 2. In this device, at least one more shell 16 in the form of an inverted (inverse) truncated cone can be placed coaxially with the conical shell 10. The upper edge of the device for preventing deposits is placed at a distance hi equal to (0.3 - 0.7) the diameter of the tubular heater 1 (D) from the lower tube plate 3 and the lower edges of the shells are placed in the same plane. The height of the shell 2 is optimally (0.5 - 1.5) the difference between the diameters of the tubular heater 1 (D) and the circulation pipe 8 (d), and the height of the inner shell may be greater than or equal to the height of the outer shell, and the solid angle of the inner shell is less than the solid outside corner. The shell 10 is provided with a cylindrical part 17, and the shell 16 is also provided with a cylindrical part 18. The cylindrical parts 17 and 18 are located at the output end of the circulation pipe 8.

The device operates as follows.

The initial solution is fed into the evaporator through the nozzle Ni mixed with the solution circulating in the apparatus. The circulating solution passes through the circulation pipe 8, from which it enters the inlet solution chamber 4, where the device 9 is located to prevent deposits of crystals in the tubes. From the inlet solution chamber 4, the solution enters the tubes of the heater 1, which is heated by heating steam supplied through the nozzle 13. Condensing on the tubes, the steam gives its heat to the solution and flows as a condensate from the heater 1 through the nozzle 15. The solution heated in the tubes of the heater 1 enters into the exit chamber 5, and then into the boiling pipe 7, where it boils. The vapor-liquid mixture from the boiling pipe 7 enters the separator 6, where the secondary vapor is separated from the evaporated solution and discharged through the nozzle 14. A portion of the evaporated solution is discharged from the apparatus through the nozzle 12, and the main part is lowered down the separator 6 and enters the circulation pipe 8 in the form circulation solution.

When the solution circulating in the apparatus moves through the circulation pipe 8, the solution makes several turns of 90 °. In these corners, there is a significant deformation of the velocity field of the solution along the cross section of the pipe 8, which is preserved when the circulating solution enters the inlet (lower) solution chamber 4.

When the circulating solution passes through the device 9 to prevent deposits of crystals in the pipes in the inlet solution chamber 4, the velocity field is aligned over the cross section of the inlet solution chamber 4 due to the presence of shells 10 and 16 in the form of inverted truncated cones placed coaxially to the chamber 4. Aligned in the inlet chamber 4 the flow of the solution evenly enters the tubes of the heater 1 and moves along them. Moreover, due to the equalization of the flow rate of the solution along the heating tubes, reverse currents and stagnant zones are eliminated and the overgrowing and clogging of the tubes with crystallizing salt is significantly reduced. In addition, by reducing the hydraulic resistance of the counter, the circulation speed increases. As a result of this, the intensity of the apparatus’s operation and its productivity increases, and the inter-flushing period and operational reliability increase.

Placing the shell 10, having the shape of an inverted truncated cone, coaxial with the inlet solution chamber 4, leads to the alignment of the velocity field of the solution along the cross section of the inlet chamber 4, since flow separation occurs at the inlet from the rotation in the circulation pipe 8 into the inlet chamber 4. When the solution is circulating in the apparatus, the part of the solution flow that is moving along the outer edge of the circulation pipe 4 (which corresponds to the maximum turning radius) is the largest. When passing this part of the flow in an annular section between the outer wall of the inlet chamber 4 and the wall of the truncated inverted cone 10, this part of the flow is distributed throughout the entire annular section, which is facilitated by the hydraulic resistance of the entrance to the annular section. Entering the remaining part of the circulating solution (uniform distribution of the velocity field, in which it is also disturbed, and most of the flow is also shifted to the outside

pipe edge) to the central part of the truncated inverted cone 10, also leads to equalization of velocities over the cross section, due to increased hydraulic resistance.

So, the presence in the inlet chamber 4 of the evaporator apparatus 9 for preventing deposits, despite the hydraulic resistance of this device, leading to an increase in the total hydraulic resistance of the circulation circuit of the apparatus, however, leads to an increase in the average circulation speed in the apparatus by 20 - 30% , This occurs despite the fact that the circulation speed is inversely proportional to the total loop resistance. The reason for the marked increase in the average circulation speed in the apparatus is apparently in equalization of the local solution speeds in the inlet chamber 4 after the device 9 and at the entrance to the heat exchange tubes.

The use in the device 9 for preventing deposits of at least one more shell 16 in the form of an inverted truncated cone, located coaxially with the main shell 10, further enhances the effect of equalizing the local velocities of the solution along the cross section of the inlet chamber 4 and in the heat exchanger tubes, As a result, the average speed increases circulation, heat transfer is intensified, productivity and inter-flushing period of the apparatus are growing.

It should also be noted that the presence in the inlet chamber 4 of the evaporation apparatus of the device 9 for preventing deposits allows it to be implemented as a short diffuser, which makes it possible to significantly reduce the height of the evaporator. The use in the device for preventing deposits 9 of at least one other shell in the form of an inverted (reverse) truncated cone located coaxially inside the first shell enhances the effect of equalizing flow rates and makes it possible to further reduce the height of the apparatus, i.e., reduce its metal consumption.

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Prevention of deposits is placed at a distance (0.3 - 0.7) of the diameter of the tubular heater from the lower tube plate 3. At a distance of less than 0.3 diameters, the smoothing effect of the device 9 on equalizing the solution speeds in the inlet chamber 4 does not have time to manifest itself in front of the tubes fully. If the distance is more than 0.7 of the diameter of the tubular heater from the lower tube plate 3, then, despite the equalization of the solution speeds, after the device is in the upper part of the inlet solution chamber 4 before the solution enters the tubes, the flow uniformity is violated. This is due to the influence on the flow of the solution, moving after the device 9 with uniform speed, sufficiently large sizes of the upper part of the solution chamber. Moreover, the speed of the solution in the upper part of the solution chamber is small and at a large distance to the entrance to the tube, as a result of the termination of the stabilizing effect of the device 9, the flow of the solution becomes less uniform.

For more efficient operation of the device 9 to prevent deposits, it is necessary that the lower edges of its constituent shells 10 and 16 were placed in the same plane. This ensures a uniform entrance of the solution circulating in the apparatus into the cone of the device 9 and a further uniform distribution of the flow. In case of violation of this condition, the solution will less uniformly enter the cone of the device 9.

To obtain the greatest effect from the use of the device 9 to prevent deposits, the height of the conical shells 10 and 16 should be limited. The indicated height must be in the range (0.5 - 1.5) of the diameter difference between the heater 1 and the circulation pipe 8. At a height less than 0.5 of the diameter difference, the leveling effect of the device is weak. If the height is greater than 1.5 of the difference in diameters, then the hydraulic resistance of the device 9 increases so much that this leads to a decrease in the total speed of the circulation of the solution in the apparatus. As a result, the intensity and productivity of the apparatus decreases.

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the height of the inner shell 16. To achieve the effect of a utility model, as shown by tests, the height of the inner shell 16 should be greater than or equal to the height of the outer 10. Increasing the height of the inner shell 16 leads to better alignment of the flow of the solution. In this case, the solution passing along the outer edge of the inner cone 16 moves up and toward the outer cone 10.

For the best distribution and equalization of the flow of the solution in the device 9, the solid angle of the inner shell 16 should be less than the solid angle of the outer shell 10. The fulfillment of this condition makes it possible to reduce the hydraulic resistance of the device 9 and, thereby, increase the speed of circulation of the solution in the apparatus. As a result, the intensity and productivity of the apparatus increases.

In order to obtain the greatest effect when leveling the velocity field, it is circulated in the solution apparatus, the conical shell 10 of the device 9 should be provided with a cylindrical part 17 connected to a smaller diameter of the truncated cone and placed at the output end of the circulation pipe 8. Also, the cylindrical part 18, placed in the circulation pipe 8, each of the shells should be provided. The presence of cylindrical shells 17 and 18 connected to the conical shells 10 and 16, located at the output end of the circulation pipe 8, allows the device 9 to capture the solution, which is located in the circulation pipe 8 and has a high speed. In this case, conditions are created for the best leveling of the velocity field of the solution as it moves in the inlet solution chamber 4 to the entrance to the heat exchange tubes under conditions of decreasing average linear velocity of the solution. The hydraulic resistance of the device 9, in the case of cylindrical shells located at the output end of the circulation pipe 8, will not change.

So, the use of the claimed evaporation apparatus for crystallizing and scale-forming solutions allowed to reduce the overgrowth and clogging of the heat exchange tubes with crystallizing salt, to intensify the work and increase the interwashing period of work. By

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/ The most increased productivity of the device. During testing, the claimed device worked without washing for 60 hours, while before the implementation of the claimed technical solution, the device worked without washing for only 20 hours. When testing the apparatus, an increase in the heat transfer coefficient, characterizing the intensity and productivity of work, was recorded by 30 - 50%, compared with the known one. AC05IW32 (

Claims (9)

1. An evaporator for crystallizing and scale-forming solutions, comprising a tubular heater with upper and lower tube boards, an inlet and outlet solution chambers, a separator connected to the heater through a boiling pipe and a circulation pipe, and a device for preventing crystal deposits in the heater pipes installed in inlet mortar chamber, characterized in that the device for preventing deposits is made in the form of a shell having the shape of a reverse truncated cone and placed coaxially inlet to the lower solution chamber. 2. The evaporator apparatus according to claim 1, characterized in that at least one more shell in the form of a reverse truncated cone is placed coaxially with the shell. 3. Evaporator according to claims 1 and 2, characterized in that the upper edge of the device for preventing deposits is placed at a distance of 0.3-0.7 diameter of the tubular heater from the lower tube board. 4. Evaporator according to claims 1 to 3, characterized in that the lower edges of the shells are placed in one plane. 5. The evaporation apparatus according to claims 1 to 4, characterized in that the shell height is (0.5-1.5) the difference in diameter between the heater and the circulation pipe. 6. Evaporator according to claims 2 to 5, characterized in that the height of the inner shell is greater than or equal to the height of the outer. 7. The evaporator according to claims 2 to 6, characterized in that the solid angle of the inner shell is less than the solid angle of the outer. 8. The evaporator apparatus according to claim 1, characterized in that the shell is provided with a cylindrical part located at the output end of the circulation pipe. 9. The evaporation apparatus according to claims 2 to 7, characterized in that each of the shells is provided with a cylindrical part located at the output end of the circulation pipe.