CN114459168A - High-temperature generator for semi-falling film type lithium bromide water chilling unit and working method thereof - Google Patents

Abstract

A high-temperature generator for a semi-falling film lithium bromide chiller and a working method thereof, the high-temperature generator comprises a cylinder, and the cylinder is provided with a plurality of rows of heat exchange tube bundles arranged along the length of the cylinder; A liquid distributor with holes is arranged above the heat exchange tube bundle, and at least one row of heat exchange tube bundles located at the bottom is immersed in the solution. The invention also includes a working method of a high temperature generator for a semi-falling film lithium bromide chiller. The invention not only overcomes the defects of the existing flooded generator, but also ensures that the bottom heat exchange tube is heated evenly and improves the heat exchange efficiency.

Description

A kind of high temperature generator for semi-falling film lithium bromide chiller and its working method

technical field

The invention relates to a lithium bromide chiller, in particular to a high temperature generator for a semi-falling film lithium bromide chiller and a working method thereof.

Background technique

The double-effect steam and hot water type lithium bromide absorption chiller uses steam or high-temperature hot water as the heat source, and concentrates the lithium bromide solution through a high-temperature generator in a vacuum environment to generate water vapor. The water vapor enters the low temperature generator as a heat source, and the lithium bromide solution is concentrated twice. Finally, the concentrated solution generated by the high temperature generator and the low temperature generator is used as an absorbent, and the generated water vapor is condensed and used as a refrigerant to prepare cold water for air conditioning and other purposes.

As shown in Figure 1: The working principle of the high temperature generator is: the dilute lithium bromide solution in the cylinder exchanges heat with the heat source in the heat exchange tube to generate water vapor, and the dilute solution becomes a concentrated solution, wherein the water vapor enters the low temperature generator. After heat exchange, the concentrated solution enters the absorber to be diluted, and then returns to the high temperature generator through the dilute solution pipeline.

The heat exchange tubes of the high temperature generator are generally all immersed in the lithium bromide solution, which is called an immersed or flooded high temperature generator. Due to the simple structure of the immersed or flooded high-temperature generator, it can ensure that the heat exchange tube contacts the solution for heat exchange, but it has the following disadvantages: (1) it requires more lithium bromide solution, which requires more resources and is costly; (2) it is relatively expensive. Many solutions require more heat source and time to reach the working temperature in the initial stage of startup; when the cooling is stopped, it takes a long time to start the cooling tower to assist in cooling down, and then the shutdown can be safely stopped; (3) The solution above the heat exchange tube is composed of pressure, preventing the solution from boiling, reducing the boiling efficiency, and increasing the temperature requirements for the heat source, thereby reducing the unit output and energy efficiency.

If the lithium bromide solution is reduced, the solution is evenly lowered onto the heat exchange tubes, and gradually dripped along the upper row of heat exchange tubes to the lowermost row of heat exchange tubes, the above-mentioned defects caused by the flooded generator can be overcome. However, due to the randomness of the droplets in the process of the droplets from the upper row of heat exchange tubes to the lower row of heat exchange tubes, the uniformity will be deteriorated, especially the bottom rows of heat exchange tubes, there may be serious uneven liquid distribution. , which affects the heat transfer efficiency. Therefore, it can not only overcome the above-mentioned defects of the flooded generator, but also avoid the poor heat exchange caused by the non-uniformity of the droplet falling process, which is an urgent technical problem to be solved by the present invention.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a high-temperature generator for a semi-falling film lithium bromide chiller with low cost, uniform heating of the bottom heat exchange tube and high heat exchange efficiency and a working method thereof.

The technical scheme of the present invention is:

A high-temperature generator for a semi-falling-film lithium bromide chiller, comprising a cylinder, in which a plurality of rows of heat exchange tube bundles arranged along the length of the cylinder are arranged; a liquid distributor with holes is arranged above the heat exchange tube bundles , and at least one row of heat exchange tube bundles at the bottom is immersed in the solution.

The above solution has the following advantages: (1) By setting the liquid distributor, the dilute solution can be distributed in the liquid distributor after entering the cylinder, and then evenly dripped onto the heat exchange tube through the holes. Fewer lithium bromide solutions require less resources and lower costs; and less solutions require less heat source and time at the initial stage of startup to reach the working temperature; when the cooling supply is stopped, it takes a shorter time to start the cooling tower, etc. Assist in cooling down and shut down quickly and safely; on the other hand, there is no pressure formed by the solution above the heat exchange tube, so the solution boils without hindrance, improving the boiling efficiency, thereby increasing the output of the unit, reducing the temperature requirements for the heat source, and improving energy efficiency and heat source utilization (2) By immersing at least one row of heat exchange tube bundles at the bottom in the solution, the randomness and inhomogeneity of the droplet falling process can be avoided, and the immersion heat exchange method can ensure that the heat exchange tube bundles at the bottom are heated evenly, Greatly improve the heat exchange efficiency. It can be said that the present invention not only overcomes the defects of the existing flooded generator, but also ensures that the bottom heat exchange tube is heated evenly and improves the heat exchange efficiency.

Further, the holes on the liquid distributor are evenly arranged, so that the solution is distributed through the liquid distributor first, and passes through the holes for heat exchange with the heat exchange tube bundle. By arranging a plurality of uniform holes, the solution can be distributed evenly, that is, evenly dripped onto the heat exchange tube bundle, thereby improving the heat exchange efficiency.

Further, N rows of heat exchange tube bundles are arranged up and down in the cylinder, and the number of rows of the heat exchange tube bundles immersed in the solution is less than N/2, forming an immersed heat exchange structure, wherein N≥3; The number of rows of heat exchange tube bundles in the solution is less than N/2. Since the droplets drip from top to bottom, the further back the heat exchange tube is located, the greater the randomness of the droplets, resulting in poor uniformity, especially the more rows of heat exchange tube bundles, the more likely this phenomenon occurs. Therefore, the heat exchange tube bundle at the rear of the present invention is selected to adopt the immersion heat exchange structure, thereby greatly improving the heat exchange efficiency.

Further, 1 to 20 rows of heat exchange tube bundles at the bottom of the cylinder are immersed in the solution. The present invention can determine the number of rows of heat exchange tube bundles that need to be soaked at the bottom according to the number of heat exchange tube bundles arranged up and down. For example, the more rows are, the more heat exchange tube bundles are soaked to ensure heat exchange efficiency. ~10 rows are soaked in lithium bromide solution.

Further, the diameter of the hole is 0.2-10 mm, preferably 1-3 mm; the center distance of the hole is 10-100 mm, preferably 20-50 mm. If the aperture is too small, it is difficult to achieve the flow of liquid distribution, and it is easy to be blocked by the dregs in the liquid; if the aperture is too large, the liquid in the liquid distributor will lose too much in the front section and lack liquid in the rear section, resulting in uneven liquid distribution; Hours, the amount of liquid cloth is small, the situation is more serious.

Further, the liquid distributor is provided with a steam channel for passing steam. Since the solution will generate steam after being heated and boiled, by setting the steam channel, the generated steam can be smoothly output from the liquid distributor.

Further, the liquid distributor is a perforated liquid distribution tray, and a gap is provided around the liquid distribution tray and the cylinder as the steam channel; or the liquid distribution tray is provided with a solution enclosure for the steam channel; or The liquid distributor includes a plurality of liquid distribution pipes arranged at intervals, the holes are opened on the liquid distribution pipes, and the space between the liquid distribution pipes forms the steam channel.

Further, the outer wall of each heat exchange tube of the heat exchange tube bundle is roughened, and the roughness is 0.5-100 μm, and the outer walls of both ends of the heat exchange tube are not roughened, leaving the bare pipe section. By roughening the surface of the heat exchange tube, the adhesion to the liquid and the thickness of the liquid film can be improved; the roughened capillary phenomenon increases the diffusion distance of the droplets; the surface roughening can also increase the surface area of the heat exchange tube, increasing the heat transfer efficiency. However, if the roughness is too large, the thickness of the liquid adsorbed on the surface will be too large, which will affect the flow and heat transfer. It can be said that the heat exchange tube of the present invention adopts a special process to roughen the outer wall of the tube, including but not limited to shot blasting, sand blasting, shot blasting, chemical corrosion, and mechanical processing; since both ends of the heat exchange tube need to be expanded, So keep the light pipe segment. Preferably, the roughness is 1 to 50 μm, more preferably 2 to 10 μm.

Further, the length of the light pipe section is 10-150 mm, preferably 15-80 mm, more preferably 20-60 mm.

A working method of a high-temperature generator for a semi-falling film lithium bromide chiller of the present invention includes the following steps: the dilute solution enters the cylinder, is first distributed in the liquid distributor, drops evenly on the heat exchange tube bundle through the hole, and exchanges the The heat source in the heat pipe conducts heat exchange, the solution is heated and boiled, and the concentrated solution enters the next row of heat exchange tube bundles for further boiling and concentration; After reaching the required concentration, it flows out of the cylinder.

The beneficial effects of the present invention are as follows: on the one hand, by setting the liquid distributor, less lithium bromide solution is needed, less resource demand and lower cost; and less solution requires less heat source and time in the initial stage of startup, which can be achieved Working temperature; when the cooling is stopped, it takes a short time to start the cooling tower to assist in cooling down, and stop quickly and safely; in addition, there is no pressure formed by the solution above the heat exchange tube, and the boiling of the solution is unobstructed, which improves the boiling efficiency and thus the output of the unit. , and reduce the temperature requirements for the heat source, improve energy efficiency and heat source utilization; on the other hand, by immersing at least one row of heat exchange tube bundles at the bottom in the solution, the randomness and non-uniformity of the droplet falling process can be avoided , The immersion heat exchange method can ensure that the heat exchange tube bundle at the bottom is heated evenly, greatly improving the heat exchange efficiency. It can be said that the present invention not only overcomes the defects of the existing flooded generator, but also ensures that the bottom heat exchange tube is heated evenly and improves the heat exchange efficiency.

Description of drawings

Figure 1 is a schematic structural diagram of an existing (immersed) high temperature generator;

Fig. 2 is the structural representation of the high temperature generator of the embodiment 1 of the present invention;

3 is a schematic diagram of the specific structure of the liquid distribution pan and the heat exchange tube in Embodiment 1 of the present invention;

4 is a schematic diagram of the specific structure of the liquid distribution pipe and the heat exchange pipe in Embodiment 3 of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

As shown in Figure 2 and Figure 3: a high-temperature generator for a semi-falling film lithium bromide chiller, comprising a cylinder body 1, and the cylinder body 1 is provided with multiple rows of heat exchange tube bundles arranged up and down along the length of the cylinder body; the A liquid distributor with holes is arranged above the heat exchange tube bundle; and at least one row of heat exchange tube bundles located at the bottom is immersed in the solution.

In this embodiment, the liquid distributor is provided with a plurality of evenly arranged holes 4 , so that the solution is first distributed through the liquid distributor, and then passes through the holes 4 for heat exchange with the heat exchange tube 2 . The diameter of the hole 4 is 3mm, and the center distance of the hole 4 is 40mm. The center distance of holes refers to the distance from the center of each hole to the center of the circle. The liquid distributor is a liquid distribution tray 3, and a plurality of holes 4 arranged at intervals are arranged on the liquid distribution tray 3 and are evenly arranged. For example, there are three rows of heat exchange tube bundles arranged up and down below the liquid distribution pan 3, and each row of heat exchange tube bundles has four heat exchange tubes 2, then the liquid distribution pan 3 is provided with four holes in each row, and the holes are The position is opposite to the position of the four heat exchange tubes; each row can be provided with multiple holes along the length of the heat exchange tubes according to requirements, and the holes are evenly arranged to ensure that the dilute solution is evenly distributed by the liquid distribution plate 3 . And the row of heat exchange tube bundles at the bottom, that is, the third row of heat exchange tube bundles, is soaked in the lithium bromide solution.

In this embodiment, a gap is provided between the liquid distribution pan 3 and at least one side of the cylinder 1 to form a steam channel 5, so that the steam generated by the boiling of the solution can be smoothly discharged through the steam channel 5, thereby reducing the pressure in the cylinder 1 and avoiding affecting the heat transfer efficiency.

In this embodiment, the outer wall of the heat exchange tube 2 is roughened, and the roughness is 6 μm, and the outer walls of both ends of the heat exchange tube are not roughened, and the bare tube sections are reserved to facilitate tube expansion. The length of the light pipe section is 30mm.

The working method of the high-temperature generator in this embodiment is as follows: after the dilute solution enters the high-temperature generator, it is first distributed in the liquid distributor, and then drips evenly onto the heat exchange tube through the holes, and high-temperature hot water or steam is passed through the heat exchange tube. The solution is heated and boiled to generate steam, and the steam is discharged to the low-pressure generator through the steam channel, the dilute solution is concentrated, and the concentrated solution enters the next row of heat exchange tubes for further boiling and concentration. And the row of heat exchange tube bundles at the bottom is immersed in the solution, heated and boiled and concentrated, and flows out from the high temperature generator after reaching the required concentration.

Example 2

The difference from Example 1 is that there are ten rows of heat exchange tube bundles arranged up and down below the liquid distribution pan, each row of heat exchange tube bundles has four heat exchange tubes, and the four rows of heat exchange tube bundles at the bottom are soaked in the solution.

Other structures are the same as those in Embodiment 1, and are not repeated here.

Example 3

As shown in Figure 4: The difference from Embodiment 1 is that the liquid distributor includes a plurality of liquid distribution pipes 3' arranged at intervals, and the number of liquid distribution pipes 3' is the same as that of each row of heat exchange pipes 2, The placement direction of the heat pipe 2 is the same, the bottom surface of the liquid distribution pipe 3' is provided with holes 4, and the holes 4 are arranged along the length direction of the liquid distribution pipe 3'; the dilute solution is placed in the liquid distribution pipe 3', so that each liquid distribution pipe 3 The dilute solution in the 'drops on the heat exchange tube 2 after being distributed through the holes. The space between each liquid distribution pipe 3' forms a steam channel 5.

In this embodiment, the diameter of the hole is 6 mm, and the center distance of the hole is 40 mm.

Other structures are the same as those in Embodiment 1, and are not repeated here.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their technical equivalents, the present invention also includes these modifications and variations.

Claims (10)

1. A high-temperature generator for a semi-falling film type lithium bromide water chilling unit comprises a cylinder body, wherein a plurality of rows of heat exchange tube bundles are arranged in the cylinder body along the length direction of the cylinder body; the device is characterized in that a liquid distributor with holes is arranged above the heat exchange tube bundles, and at least one row of heat exchange tube bundles positioned at the bottom are soaked in the solution.

2. The high temperature generator for a semi-falling film lithium bromide chiller according to claim 1 wherein the holes in the distributor are evenly spaced such that the solution is distributed by the distributor and passes through the holes to exchange heat with the heat exchanger tube bundle.

3. The high temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 1, wherein N rows of heat exchange tube bundles are arranged in the cylinder up and down, the number of rows of heat exchange tube bundles soaked in the solution is less than N/2, and an immersion type heat exchange structure is formed, wherein N is more than or equal to 3.

4. The high temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 3, wherein 1-20 rows of heat exchange tube bundles at the bottom of the cylinder are immersed in the solution.

5. The high temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 1, wherein the diameter of the hole is 0.2-10 mm, and the center distance of the hole is 10-100 mm.

6. The high temperature generator for a semi-falling film lithium bromide water chiller according to claim 1, wherein the liquid distributor is provided with a steam channel for passing steam.

7. The high temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 6, wherein the liquid distributor is a perforated liquid distribution disc, and a gap is formed between the liquid distribution disc and the periphery of the cylinder body to serve as the steam channel; or the liquid distribution disc is provided with the steam channel with the solution enclosure; or the liquid distributor comprises a plurality of liquid distributing pipes which are arranged at intervals, the holes are arranged on the liquid distributing pipes, and the space between the liquid distributing pipes forms the steam channel.

8. The high-temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 1, wherein the outer walls of the heat exchange tubes of the heat exchange tube bundle are roughened, the roughness is 0.5-100 μm, the outer walls of two ends of each heat exchange tube are not roughened, and a light tube section is reserved.

9. The high temperature generator for the semi-falling film lithium bromide water chilling unit according to claim 8, wherein the length of the light pipe section is 10-150 mm.

10. A working method of a high-temperature generator for a semi-falling film type lithium bromide water chilling unit is characterized by comprising the following steps: the dilute solution enters the cylinder body, is distributed by the liquid distributor, uniformly drops on the heat exchange tube bundles through the holes, exchanges heat with a heat source in the heat exchange tubes, is heated to boil, and then enters the next row of heat exchange tube bundles for further boiling and concentration; the heat exchange tube bundle at the bottom is soaked into the solution, and the solution at the part is directly boiled and concentrated to reach the required concentration and then flows out of the cylinder.

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