Low-temperature heat-driven variable-diameter rectifying ammonia absorption refrigerator

Abstract

The application discloses a low-temperature heat-driven variable-diameter rectification ammonia absorption refrigerator, which comprises a rectification tower, a condenser, a tower plate, a stripping liquid distributor, a filler and a falling film generator which are integrally formed from top to bottom; a cooler which is communicated with the condenser through a nitrogen gas conveying pipeline at the top of the condenser; the cooler is also communicated with an evaporator; a falling film absorber which is communicated with a metering pump through a concentrated ammonia water conveying pipeline; the metering pump conveys the concentrated ammonia water to the condenser through a first branch pipe, and conveys the concentrated ammonia water to the stripping liquid distributor through a second branch pipe and a plate heat exchanger; the falling film generator conveys dilute ammonia water to the falling film absorber through a dilute ammonia water conveying pipeline and the plate heat exchanger. The application can widen the application range of a low-temperature heat source in an ammonia absorption refrigerator, improve the separation efficiency of ammonia water, increase internal heat recovery utilization to improve the efficiency of the refrigerator, reduce the ammonia water storage in the system, make the system respond quickly, and reduce the area and volume of the absorption refrigerator.

Description

Technical Field

[0001] This invention belongs to the technical field of ammonia absorption chillers, and particularly relates to a low-temperature thermally driven variable-diameter distillation ammonia absorption chiller. Background Technology

[0002] The increasing prevalence of power shortages during summer and winter highlights the challenges of energy conservation. Refrigeration (air conditioning, refrigerators, and cold storage), being major energy consumers, can significantly reduce energy consumption by utilizing low-temperature heat energy to drive absorption refrigeration systems. Solar energy and industrial waste heat can power absorption refrigeration systems. Ammonia absorption refrigeration systems can be used for both refrigeration and freezing; however, ammonia absorption refrigeration typically uses heat sources above 120℃. Therefore, utilizing low-temperature heat sources around 100℃ is crucial for the widespread adoption of ammonia absorption refrigeration systems. Furthermore, ammonia absorption refrigeration efficiency is often around 0.5. Reducing the heat transfer temperature difference in heat exchange equipment and improving distillation efficiency can enhance overall efficiency.

[0003] Industrial ammonia absorption chillers often use total condensers for reflux, resulting in excessive liquid reflux and low ammonia separation efficiency. Furthermore, the heat from distillation cannot be recovered, leading to low thermal efficiency of the refrigeration system. The system response lags when operating conditions change. Generation, distillation, and absorption are all processes involving simultaneous heat and mass transfer. However, in existing technologies, to enhance heat and mass transfer, generators and absorbers often require circulation components to increase the spray volume. This results in large ammonia storage and an excessive number of other components, leading to a large system size and significant lag in regulation. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature thermally driven variable-diameter distillation ammonia absorption chiller to solve the above-mentioned problems, thereby broadening the application range of low-temperature heat sources in ammonia absorption chillers, improving the separation efficiency of ammonia and water, increasing internal heat recovery utilization to improve the efficiency of the chiller, reducing the amount of ammonia and water stored in the system, making the system respond quickly, and reducing the area and volume of the absorption chiller prototype.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller, comprising:

[0007] A distillation column includes a condenser, trays, stripping distributor, packing, and falling film generator, all integrally formed from top to bottom.

[0008] The condenser is connected to a cooler via a nitrogen supply pipe at its top; the cooler is also connected to an evaporator.

[0009] A falling film absorber is connected to a metering pump via a concentrated ammonia water delivery pipeline; the metering pump delivers concentrated ammonia water to the condenser via a first branch pipe, and also delivers concentrated ammonia water to the stripping distributor via a second branch pipe and a plate heat exchanger.

[0010] The falling film generator supplies dilute ammonia water to the falling film absorber through a dilute ammonia water delivery pipeline and a plate heat exchanger.

[0011] The trays are arranged in an alternating pattern of at least three pieces, and at least one side of each tray is fixedly installed on the inner wall of the distillation column; the trays are provided with a group of exhaust holes; the first branch pipe passes through the condenser and extends above the second tray from top to bottom.

[0012] The cooler is a coupling of a condenser and a subcooler; one end of the nitrogen delivery pipeline is connected to the condenser, which is used to condense ammonia into liquid ammonia; the liquid ammonia passes through the subcooler and is delivered to the evaporator through the liquid ammonia delivery pipeline, which is equipped with a liquid ammonia throttling valve; the evaporator is used to evaporate the liquid ammonia, and the evaporated ammonia passes through the subcooler and enters the falling film absorber.

[0013] The distillation distributor adopts a double-layer distribution method.

[0014] The diameter of the distillation distributor is 1.5 times the diameter of the tray; the falling film generator is a horizontal falling film generator.

[0015] The dilute ammonia water delivery pipes on both sides of the plate heat exchanger have the same flow rate as the second branch pipe.

[0016] A dilute ammonia water throttling valve is also installed at the connection between the dilute ammonia water delivery pipeline and the falling film absorber.

[0017] A concentrated ammonia water regulating valve is also installed at the connection between the first branch pipe and the metering pump.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] (1) Since the ammonia desorption process is a heating process, falling film desorption is used to reduce the outlet temperature of the driving heat source and improve the ammonia separation efficiency, so that the temperature difference in the heat transfer process is uniform and the utilization rate of the heat source is improved.

[0020] (2) Using a portion of concentrated ammonia water as the cooling medium for the fractional condenser to recover the heat of distillation, the concentrated ammonia water after heat exchange directly enters the top of the second tray; the structure of the distillation column is narrow at the top and wide at the bottom, and the combination of the plate column and the packed column ensures the high efficiency of distillation under small reflux; the distillation structure from top to bottom is a micro U-shaped fractional condenser - plate distillation - packed stripping - horizontal falling film desorption structure, the whole combination is formed as one piece, with high efficiency and integration.

[0021] (3) The cooler is a three-stream heat exchanger that couples a condenser with a subcooler. Ammonia is condensed outside the spiral tube, and the second stream is cooling water. After the ammonia is condensed, it is subcooled outside the spiral coil, and the third stream is the evaporated ammonia.

[0022] (4) The use of falling film absorbers greatly reduces the hysteresis effect of absorption concentration changes on system operation, which not only reduces the equipment volume, but also effectively prevents the solution pump from being trapped by air.

[0023] (5) Both the generation and desorption processes are falling film processes. The amount of ammonia water stored in the generator and absorber is very small. The system operation feedback adjustment is rapid, which facilitates system control and greatly improves the stability and adaptability of the system operation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0026] Among them, 101 is a condenser, 102 is a tray, 103 is a stripping distributor, 104 is packing, 105 is a falling film generator, 106 is a cooler, 107 is a plate heat exchanger, 108 is a liquid ammonia throttling valve, 109 is an evaporator, 110 is a dilute ammonia throttling valve, 111 is a falling film absorber, 112 is a metering pump, and 113 is a concentrated ammonia regulating valve. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] As attached Figure 1 As shown, the following solution is provided: A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller of the present invention includes:

[0030] The distillation column includes a condenser 101 integrally formed from top to bottom, a tray 102, a stripping distributor 103, packing 104, and a falling film generator 105.

[0031] The top of the cooler 106 and the condenser 101 are connected to the cooler 106 via a nitrogen supply pipe; the cooler 106 is also connected to the evaporator 109.

[0032] The falling film absorber 111 is connected to the metering pump 112 through a concentrated ammonia water delivery pipeline; the metering pump 112 delivers concentrated ammonia water to the condenser 101 through the first branch pipe, and the metering pump 112 also delivers concentrated ammonia water to the distillation distributor 103 through the second branch pipe and the plate heat exchanger 107.

[0033] The falling film generator 105 supplies dilute ammonia water to the falling film absorber 111 through a dilute ammonia water delivery pipeline and a plate heat exchanger 107.

[0034] At least three trays 102 are arranged in an alternating pattern, and at least one side of the tray 102 is fixedly installed on the inner wall of the distillation column; a group of vent holes is provided on the tray 102; the first branch pipe passes through the condenser 101 and extends above the second tray 102 from top to bottom.

[0035] Cooler 106 is formed by coupling a condenser and a subcooler; one end of the nitrogen delivery pipeline is connected to the condenser, which is used to condense ammonia into liquid ammonia; the liquid ammonia passes through the subcooler and is delivered to the evaporator 109 through the liquid ammonia delivery pipeline, and a liquid ammonia throttle valve 108 is installed on the liquid ammonia delivery pipeline; the evaporator 109 is used to evaporate the liquid ammonia, and the evaporated ammonia enters the falling film absorber 111 through the subcooler.

[0036] The distillation distributor 103 adopts a double-layer distribution form.

[0037] The diameter of the stripping distributor 103 is 2.5 times the diameter of the tray 102; the falling film generator 105 is a horizontal falling film generator.

[0038] The dilute ammonia water delivery pipes on both sides of plate heat exchanger 107 have the same flow rate as the second branch pipe.

[0039] A dilute ammonia water throttling valve 110 is also installed at the connection between the dilute ammonia water delivery pipeline and the falling film absorber 111.

[0040] A concentrated ammonia water regulating valve 113 is also installed at the connection between the first branch pipe and the metering pump 112.

[0041] In one embodiment of the present invention, the evaporator 109 is selected as a flooded evaporator.

[0042] In one embodiment of the present invention, the metering pump 112 is the only driving device in the device.

[0043] In one embodiment of the present invention, the working process is as follows: concentrated ammonia water is transported from the falling film absorber 111 to the metering pump 112, and the metering pump 112 transports the concentrated ammonia water to the rectification section of the distillation column through the first branch pipe; it can also be transported through the second branch pipe as a delivery branch, and part of the concentrated ammonia water is controlled by the concentrated ammonia water regulating valve 113 as the cold fluid of the top condenser 101 of the distillation column, so that the ammonia gas is condensed and refluxed as reflux liquid to recover the heat of rectification; the main concentrated ammonia water flow rate is equivalent to the dilute ammonia water flow rate and heat is exchanged in the completely countercurrent plate heat exchanger 107 to ensure the consistency of the heat transfer temperature difference at both ends of the heat exchanger and reduce the heat dissipation (fire accumulation) in the heat transfer process.

[0044] Furthermore, the concentrated ammonia water after heat exchange in the condenser 101 directly enters the second tray 102 at the top of the distillation column, where it serves as reflux liquid in the rectification section along with the condensate. Then, together with the concentrated ammonia water 10 from the solution heat exchanger 107, it is collected in the stripping distributor 103 as the liquid phase in the stripping section 104. Finally, the ammonia water at the stripping section outlet is collected above the generator, where it desorbs to produce ammonia gas in the falling film generator 105. The waste heat source of the falling film generator enters from the lower tube side 15 and exits from the upper tube side 14, with the ammonia water flowing counter-currently to ensure a consistent temperature difference during the heat transfer process and efficient utilization of the low-temperature heat source.

[0045] Furthermore, the falling film generator 105 will also produce dilute ammonia water, which is transported back to the top of the falling film absorber 111 through the plate heat exchanger 107 to absorb the superheated low-pressure ammonia gas. The bottom of the falling film absorber 111 is equipped with a structure as a concentrated ammonia water storage tank, thereby completing the absorption refrigeration cycle.

[0046] Furthermore, the falling film generator 105 utilizes a low-temperature waste heat source of 80-100℃.

[0047] Furthermore, the low-pressure ammonia is ammonia produced from the evaporator 109 after evaporation in the cooler 106.

[0048] In one embodiment of the present invention, the exhaust port group opened on the tower plate 102 is used for the ammonia gas formed by evaporation to pass through, and is transported to the cooler 106 through the ammonia gas delivery pipe.

[0049] In one embodiment of the present invention, the cooler is a three-stream heat exchanger with a condenser coupled to a subcooler. Ammonia is condensed outside the spiral tube, the second stream is cooling water; after the ammonia is condensed, it is subcooled outside the spiral coil, and the third stream is the evaporated ammonia.

[0050] Furthermore, the ammonia leaving the distillation column is condensed and subcooled in cooler 106 (reducing throttling expansion losses) to increase the refrigeration capacity of ammonia per unit flow rate; then it enters the flooded evaporator 109 through the liquid ammonia throttling valve 108 for evaporation, and the evaporated ammonia is used as the third stream of the cooler for heat exchange before entering the absorber 111 for absorption.

[0051] In one embodiment of the present invention, a flooded evaporator stores liquid ammonia and adaptively adjusts the concentration of concentrated ammonia water according to operating conditions.

[0052] In one embodiment of the present invention, a cylindrical structure with a height of 15cm and a diameter of 4 times that of the pipe is provided below the falling film absorber 111 to integrate the absorber and the concentrated ammonia water storage tank, thereby reducing the hysteresis effect of ammonia water concentration changes on the system.

[0053] In one embodiment of the invention, the evaporator 109 is a flooded evaporator, used to store liquid ammonia and adaptively adjust the concentration of concentrated ammonia water according to changes in operating conditions. In the plate heat exchanger 107, the flow rates of dilute and concentrated ammonia water are equal. The completely counter-current plate heat exchanger ensures the uniformity of the temperature difference during heat transfer, reducing the system's (exergy) losses. The absorption method is horizontal tube falling film absorption. A liquid collection device is installed at the absorber outlet, integrating the absorber and concentrated ammonia water storage tank. This effectively prevents pump cavitation and reduces the hysteresis effect of concentration changes after absorption on system operation.

[0054] In one embodiment of the present invention, the first branch of the pressurized concentrated ammonia water serves as the cooling medium for the condenser 101 to recover the heat of condensation. The condenser 101 is a micro U-shaped heat exchange tube. Ammonia gas condenses outside the micro U-shaped tube, and the condensate reflux liquid drips directly onto the top of the first tray 102. The concentrated ammonia water enters from the upper tube side of the condenser 101 and flows out from the lower tube side. The concentrated ammonia water after heat exchange directly enters the second tray 102 through the downcomer of the first tray 102, increasing the liquid reflux flow rate.

[0055] A stripping distribution tank is installed below the rectification section. The liquid from the rectification section outlet (first branch pipe) and the concentrated ammonia water from the plate heat exchanger 107 (second branch pipe) are used together as the reflux liquid for the stripping section. The concentrated ammonia water is mainly fed from the second tray 102 at the bottom of the column. The distribution tank is installed above the falling film generator 105 to evenly distribute the ammonia water on the falling film generator 105. The concentrated ammonia water undergoes falling film desorption in the falling film generator 105.

[0056] Furthermore, the usable waste heat enters from the bottom of the falling film generator 105 tube side and flows out from the top, improving the utilization rate of the low-temperature heat source. In the ammonia purification process, the liquid flow rates of the rectification section and the stripping section differ significantly. The rectification column adopts a variable diameter design—narrower at the top and wider at the bottom—while the diameter of the stripping section is 2.5 times that of the rectification section. Moreover, the rectification section uses a tray system, while the stripping section uses a packed system.

[0057] Furthermore, the ammonia gas generated by falling film desorption in the generator is initially purified using concentrated ammonia water, and then passes through a rectification section and a fractionating condenser to achieve an ammonia purity of over 99.9%.

[0058] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0059] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller, characterized in that, include: The distillation column includes a condenser (101) integrally formed from top to bottom, a tray (102), a stripping distributor (103), packing (104), and a falling film generator (105). The cooler (106) is connected to the top of the condenser (101) via a nitrogen supply pipe; the cooler (106) is also connected to the evaporator (109); A falling film absorber (111) is connected to a metering pump (112) via a concentrated ammonia water delivery pipeline; the metering pump (112) delivers concentrated ammonia water to the condenser (101) via a first branch pipe, and also delivers concentrated ammonia water to the distillation distributor (103) via a second branch pipe and a plate heat exchanger (107); the metering pump (112) is the only driving device in this unit; The falling film generator (105) supplies dilute ammonia water to the falling film absorber (111) through a dilute ammonia water delivery pipeline and a plate heat exchanger (107); The cooler (106) is a three-flow heat exchanger that couples a condenser to a subcooler; one end of the nitrogen delivery pipe is connected to the condenser, which is used to condense ammonia into liquid ammonia; the liquid ammonia passes through the subcooler and is delivered to the evaporator (109) through the liquid ammonia delivery pipe, and a liquid ammonia throttle valve (108) is installed on the liquid ammonia delivery pipe; the evaporator (109) is used to evaporate the liquid ammonia, and the evaporated ammonia enters the falling film absorber (111) through the subcooler; The diameter of the distillation distributor (103) is 2.5 times the diameter of the tray (102); the falling film generator (105) is a horizontal falling film generator.

2. The low-temperature thermally driven variable-diameter distillation ammonia absorption chiller according to claim 1, characterized in that: At least three trays (102) are arranged in an alternating pattern. At least one side of each tray (102) is fixedly installed on the inner wall of the distillation column. A group of exhaust holes is provided on each tray (102). The first branch pipe passes through the condenser (101) and extends above the second tray (102) from top to bottom.

3. The low-temperature thermally driven variable-diameter distillation ammonia absorption chiller according to claim 1, characterized in that: The distillation distributor (103) adopts a double-layer distribution form.

4. A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller according to claim 1, characterized in that: The dilute ammonia water delivery pipes on both sides of the plate heat exchanger (107) have the same flow rate as the second branch pipe.

5. A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller according to claim 1, characterized in that: A dilute ammonia water throttling valve (110) is also installed at the connection between the dilute ammonia water delivery pipeline and the falling film absorber (111).

6. A low-temperature thermally driven variable-diameter distillation ammonia absorption chiller according to claim 1, characterized in that: A concentrated ammonia water regulating valve (113) is also installed at the connection between the first branch pipe and the metering pump (112).

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