Heat exchanger

Abstract

The purpose of the present invention is to provide a heat exchanger which is used in an air separation device having a low-pressure tower, a high-pressure tower, and a mixing tower, and which is capable of suppressing an increase in equipment cost. The invention relates to a heat exchanger for use in an air separation device (1100) having a low-pressure column (600), a high-pressure column (500) and a mixing column (400), characterized in that the heat exchanger is constructed of plates and fins and is intended for separating air from the low-pressure column (600) by means of at least one cold flow gas (C2 and C3) withdrawn from the low-pressure column (600) and a cold flow gas (C1) withdrawn from the mixing column (400). Warm flow gases (at least one of W1, W2 and W3) as at least a part of raw material air and at least one warm flow liquid (at least one of W4 and W5) extracted from the mixing tower (400) are cooled, and cold flow liquid (C6) extracted from the low-pressure tower (600) via a booster pump (800) and supplied to the mixing tower (400) is heated.

Description

Technical Field

[0001] The present invention relates to a heat exchanger used in an air separation device having a low-pressure column, a high-pressure column and a mixing column, and for cooling raw air and heating liquid supplied from the low-pressure column to the mixing column. Background Art

[0002] In an air separation device, a mixing tower is sometimes used in addition to a low-pressure tower and a high-pressure tower. In general, in an air separation device using a mixing tower, low-purity oxygen with an oxygen concentration of about 97% or less is produced as product oxygen. In the mixing tower, liquid oxygen from the top of the tower is directly contacted with gaseous air from the bottom of the tower to convert the liquid oxygen into low-purity oxygen, and the low-purity oxygen is taken out from the top of the tower as product oxygen.

[0003] The liquid oxygen supplied to the top of the tower is obtained by pressurizing the liquid oxygen at the bottom of the low-pressure tower with a pump, and its temperature is lower than the boiling point at the boosted pressure. Therefore, if it is supplied to the low-pressure tower in this state, the flow rate of the product oxygen from the top of the mixing tower is reduced, and the flow rate of the liquid air from the bottom of the tower is increased, which is the main reason for reducing the oxygen yield of the air separation device.

[0004] Therefore, the following process is disclosed: in a heater for heating liquid oxygen pressurized by a pump, the liquid oxygen is heat exchanged with a side-cut liquid and a container discharge liquid discharged from a mixing tower, and then in an auxiliary heat exchanger, the liquid oxygen is heated by heat exchange with gaseous air and supplied to the mixing tower after being brought close to the saturation temperature (for example, refer to Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-28572

[0006] However, in order to heat the liquid oxygen after the pressure is increased by the pump, a heater and an auxiliary heat exchanger need to be installed, and pipes leading to these devices need to be installed. Furthermore, in order to accommodate these devices and pipes, the cold box becomes larger, so the equipment cost increases, which becomes a problem. Summary of the invention

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a heat exchanger used in an air separation device having a low-pressure column, a high-pressure column and a mixing column, and capable of suppressing an increase in equipment cost.

[0008] (1) The heat exchanger of the present invention is used in an air separation device having a low-pressure tower, a high-pressure tower and a mixing tower, and is characterized in that:

[0009] The heat exchanger is constructed of plates and fins, and

[0010] Used to cool the warm flow gas as at least a part of the raw air and at least one warm flow liquid taken out from the mixing tower by using at least one cold flow gas taken out from the low-pressure tower and the cold flow gas taken out from the mixing tower, and to heat the cold flow liquid taken out from the low-pressure tower via a booster pump and supplied to the mixing tower.

[0011] (2) In addition, the heat exchanger according to (1) above is used to cool at least one warm fluid taken out from the high-pressure column.

[0012] (3) In addition, the heat exchanger according to the above (1) or (2) is characterized in that it comprises: a cold fluid passage for the cold fluid to flow; a cold fluid gas passage for the cold fluid gas to flow; a warm fluid passage for the warm fluid to flow; and a warm fluid gas passage for the warm fluid gas to flow, the warm fluid gas passage being configured so that the warm fluid gas flows in a countercurrent manner relative to the cold fluid and the cold fluid, and the warm fluid passage being configured so that the warm fluid flows in a cross-current manner relative to the cold fluid and the cold fluid.

[0013] According to the present invention, the number of machines can be reduced and the cold box can be made compact, thereby reducing equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an explanatory diagram of an air separation device including the heat exchanger according to the first embodiment.

[0015] Figure 2 It is an explanatory diagram of the internal structure of the heat exchanger according to the first embodiment.

[0016] Figure 3 It is an explanatory diagram of an air separation device including a heat exchanger according to a second embodiment. DETAILED DESCRIPTION

[0017] (First Embodiment)

[0018] Figure 1 This is a diagram showing an example of an air separation device using the heat exchanger of this embodiment.

[0019] like Figure 1As shown, the heat exchanger 110 of the present embodiment is a heat exchanger used in the air separation device 1100 having the low-pressure tower 600, the high-pressure tower 500 and the mixing tower 400. The heat exchanger 110 of the present embodiment is characterized in that the heat exchanger is constructed of plates and fins, and is used to cool the warm-flow gas (at least one of W1, W2 and W3) as at least a part of the raw material air and at least one warm-flow liquid (at least one of W4 and W5) taken out from the mixing tower 400 by at least one cold-flow gas (at least one of C2 and C3) taken out from the low-pressure tower 600 and the cold-flow gas C1 taken out from the mixing tower 400, and to heat the cold-flow liquid C6 taken out from the low-pressure tower 600 via the booster pump 800 and supplied to the mixing tower 400.

[0020] First, based on Figure 1 The overall structure of the air separation device 1100 including the heat exchanger 110 will be described, and then the internal structure of the heat exchanger 110 will be described.

[0021] In this specification, as symbols indicating fluids, symbols marked with "C" (the initials of cold) indicate that the fluid is a cold fluid, and symbols marked with "W" (the initials of warm) indicate that the fluid is a warm fluid.

[0022] <Description of the Structure of the Air Separation Device>

[0023] The air separation device 1100 includes a high-pressure column 500 , a low-pressure column 600 , a mixing column 400 , a subcooler 190 , and a heat exchanger 110 .

[0024] A part W2 of the raw air W1, W2, and W3 compressed by the compressor 90 and purified by the purifier 91 is supplied to the heat exchanger 110 through the pipeline 21. In the heat exchanger 110, a part W2 of the raw air is cooled by heat exchange with the product oxygen C1 supplied from the top of the mixing tower 400 through the pipeline 1, the nitrogen C2 supplied from the top of the low-pressure tower 600 through the subcooler 190 and through the pipeline 2, the medium-pressure nitrogen C3 supplied from the top of the high-pressure tower 500 through the pipeline 3, and the liquid oxygen C6 pressurized by the booster pump 800 from the bottom of the low-pressure tower 600, and supplied to the bottom of the high-pressure tower 500 through the pipeline 22.

[0025] In addition, another part W1 of the raw air is pressurized by the recompressor 92 and then supplied to the heat exchanger 110 through the pipeline 11. In the heat exchanger 110, another part W1 of the raw air is cooled by heat exchange with the product oxygen C1, nitrogen C2, medium-pressure nitrogen C3 and liquid oxygen C6 as cold fluids and then supplied to the bottom of the mixing tower 400 through the pipeline 13.

[0026] Furthermore, another part W3 of the raw air is pressurized by the re-compressor 93 and supplied to the heat exchanger 110 through the pipeline 31. In the heat exchanger 110, it is cooled by exchanging heat with the product oxygen C1, nitrogen C2 and medium-pressure nitrogen C3 as cold fluids, and then expanded by the expansion turbine 94 and supplied to the low-pressure tower 600 through the pipeline 32.

[0027] A portion W2 of the raw air supplied to the bottom of the high-pressure tower 500 through the pipeline 22 is concentrated as nitrogen as a low-boiling-point component while ascending by contacting the gas-liquid of the reflux liquid flowing down in the tower, thereby generating nitrogen gas at the top of the tower.

[0028] In addition, oxygen-enriched liquid air rich in oxygen, which is a high-boiling-point component, is generated at the bottom of the high-pressure column 500 , and the oxygen-enriched liquid air is extracted through a pipeline 53 .

[0029] The nitrogen generated in the high-pressure tower is liquefied in the main condenser 300 , a portion of which is supplied to the subcooler 190 through the pipeline 51 to be cooled, and is decompressed through the pipeline 52 and supplied to the top of the low-pressure tower 600 as a reflux liquid.

[0030] In addition, the liquid air extracted from the bottom of the high-pressure tower 500 through the pipeline 53 is supplied to the subcooler 190 through the pipeline 43 together with the liquid air taken out from the mixing tower 400 through the pipeline 41, the heat exchanger 110 and the pipeline 42 to be cooled, and is supplied to the low-pressure tower 600 as a reflux liquid after being reduced in pressure through the pipeline 44.

[0031] It should be noted that the cooling source of the liquid in the subcooler 190 is nitrogen supplied from the top of the low-pressure tower 600 through the pipeline 60 .

[0032] The reflux liquid supplied to the low-pressure tower 600 is concentrated as oxygen, a high-boiling-point component, while flowing down by gas-liquid contact with the rising gas in the tower, thereby generating liquid oxygen at the bottom of the tower. In addition, the rising gas is concentrated as nitrogen, a low-boiling-point component, while rising, thereby generating nitrogen gas at the top of the tower.

[0033] The liquid oxygen C6 generated at the bottom of the low-pressure tower 600 is taken out through the pipeline 61, and after being pressurized by the booster pump 800, it is guided to the heat exchanger 110 through the pipeline 62. In the heat exchanger 110, the pressurized liquid oxygen C6 exchanges heat with the liquid (hereinafter referred to as "side-cut liquid") W5 cut from the mixing tower 400 through the pipeline 45, the container discharge liquid W4 of the pipeline 41, and parts of the raw material air W1 and W2, and is heated, and then taken out through the pipeline 64 and supplied to the top of the mixing tower 400.

[0034] In the mixing tower 400, the supplied liquid oxygen directly contacts the gaseous air introduced through the pipeline 13, and produces low-purity product oxygen C1 in the pipeline 1 from the top of the tower.

[0035] <Description of Heat Exchanger>

[0036] As the heat exchanger 110 , a plate-fin type heat exchanger having a structure in which plates and fins are stacked in layers can be used. Figure 2 This is a diagram showing each layer of the heat exchanger 110 separated into each flow path.

[0037] like Figure 2 As shown, the heat exchanger 110 has three warm fluid passages A1-A3 and three cold fluid passages B1-B3.

[0038] Furthermore, the warm fluid passage A1 includes a warm flow gas passage a1 through which the warm flow gas W1 flows, between the warm end side and the cold end side.

[0039] In addition, the warm fluid passage A2 is divided into two flow areas between the warm end side and the cold end side. The partition on the warm end side has a warm flow gas passage a2 for the warm flow gas W2 to flow, and the partition on the cold end side has a warm flow liquid passage a4 for the warm flow liquid W4 to flow.

[0040] In addition, the warm fluid passage A3 is divided into two flow areas between the warm end side and the cold end side. The partition on the warm end side has a warm flow gas passage a3 for the warm flow gas W3 to flow, and the partition on the cold end side has a warm flow liquid passage a5 for the warm flow liquid W5 to flow.

[0041] In addition, the cold fluid passage B1 is divided into two flow areas between the warm end side and the cold end side. The partition on the warm end side has a cold flow gas passage b1 for the cold flow gas C1 to flow, and the partition on the cold end side has a cold flow liquid passage b6 for the cold flow liquid C6 to flow.

[0042] In addition, the cold fluid passage B2 has a cold flow gas passage b2 through which the cold flow gas C2 flows between the warm end side and the cold end side.

[0043] In addition, the cold fluid passage B3 has a cold flow gas passage b3 through which the cold flow gas C3 flows between the warm end side and the cold end side.

[0044] In addition, the warm flow gas passages a1, a2, and a3 (see Figure 2 (a), (b), (c)) are arranged relative to the cold flow gas passages b1, b2, b3 (refer to Figure 2 (d), (e), (f)) and a cold fluid passage b6 for the flow of liquid oxygen C6 as a cold fluid (refer to Figure 2 (d)) flows by convection.

[0045] In addition, the warm fluid passages a4 and a5 (see FIG. 1 ) are provided for the container discharge liquid W4 and the side cut liquid W5 as warm fluids drawn out from the mixing tower 400 through the pipes 41 and 45. Figure 2 (b), (c)) are arranged relative to the cold flow gas passages b2 and b3 (refer to Figure 2 (e), (f)) and a cold fluid passage b6 for the flow of liquid oxygen C6 as a cold fluid (refer to Figure 2 (d)) flows in a cross-current manner.

[0046] The passage for the container to discharge the liquid W4 (refer to Figure 2 (b)) is composed of five paths, the path of the episiotomy fluid W5 (refer to Figure 2 (c)) is constructed from seven paths.

[0047] like Figure 2 As shown in (b), the container discharge liquid W4 of the mixing tower 400 extracted through the pipeline 41 flows into the inlet in of the passage, flows in a cross direction relative to the nitrogen C2, the medium-pressure nitrogen C3 and the liquid oxygen C6, then flows in the opposite direction in the path arranged on the cold end side, and is discharged from the outlet out through a total of five paths.

[0048] like Figure 2 As shown in (c), the side cut liquid W5 of the mixing tower 400 drawn out through the pipeline 45 flows in from the inlet in, flows in a cross direction with respect to the nitrogen C2, the medium pressure nitrogen C3 and the liquid oxygen C6, then flows in the opposite direction in the path arranged on the cold end side, and is discharged from the outlet out through a total of seven paths. The inlet in of these container discharge liquids W4 and the side cut liquid W5 is set on the warm end side relative to the respective outlets out, and is connected to the mixing tower 400 through pipelines 41 and 45.

[0049] It should be noted that in this embodiment, if Figure 2 As shown in (b) and (c), the passages for the container discharge liquid W4 and the side cutting liquid W5 are separated and arranged below the passages for the raw air W2 and W3, respectively, but can also be arranged below the passages for the raw air W1 and the product oxygen C1.

[0050] In addition, the outlet out of the liquid oxygen C6 connected to the top of the mixing tower 400 and the inlet in of the side-cut liquid W5 connected to the side-cut portion of the mixing tower 400 are arranged on the warm end side of the outlet out of the raw air W1 and W2. This is a case where the arrangement is made in a manner that increases the heat exchange efficiency in consideration of the temperature of each fluid. Such an arrangement is possible because it is an integrated heat exchanger 110. In this sense, the heat exchanger 110 is not simply a product of combining the heater and auxiliary heat exchanger that are separately provided in the previous examples with the main heat exchanger side by side. However, it can also be arranged on the cold end side according to the pressure of the mixing tower 400.

[0051] As described above, since the heat exchanger 110 has the above-mentioned functions, it is not necessary to provide a heater or an auxiliary heat exchanger which are separately provided in the conventional examples, thereby reducing the cold box space for accommodating these devices and reducing the equipment cost.

[0052] (Second Embodiment)

[0053] Figure 3 1 is a diagram showing an air separation device 1200 using the heat exchanger 120 of the second embodiment. The air separation device 1200 includes a high-pressure column 500, a low-pressure column 600, a mixing column 400, and the heat exchanger 120. Figure 3 In, with Figure 1 The same parts are denoted by the same reference numerals.

[0054] Heat exchanger 120 relative to Figure 1 , Figure 2 The heat exchanger 110 shown has added a passage for cooling the liquid containing oxygen-rich liquid air (hereinafter referred to as "oxygen-rich liquid air") introduced from the bottom of the high-pressure tower 500 through the pipeline 43, and a passage for cooling the liquid nitrogen W7 introduced from the main condenser 300 through the pipeline 51.

[0055] The cooling sources of these oxygen-enriched liquid air W6 and liquid nitrogen W7 are nitrogen C2 introduced into the heat exchanger 120 from the top of the low-pressure tower 600 through the pipeline 60, and medium-pressure nitrogen C3 introduced into the heat exchanger 120 from the top of the high-pressure tower 500 through the pipeline 3.

[0056] The oxygen-enriched liquid air W6 and liquid nitrogen W7 cooled by the heat exchanger 120 are taken out through pipelines 44 and 52, respectively, and supplied to the low-pressure column 600 after being decompressed.

[0057] Thus, the heat exchanger 120 eliminates the need for the conventional heater, auxiliary heat exchanger, and supercooler 190 provided in the first embodiment, thereby reducing the cold box space for accommodating these devices and reducing equipment costs.

[0058] Description of Reference Numerals

[0059] 1100, 1200 air separation unit

[0060] 800 Booster Pump

[0061] 500 High-pressure tower

[0062] 600 Low Pressure Tower

[0063] 400 Mixing Tower

[0064] 300 Main Condenser

[0065] 190 Subcooler

[0066] 110, 120 heat exchanger

[0067] 90 Compressor

[0068] 91 Purifier

[0069] 92, 93 Recompressor

[0070] 94 Expansion Turbine

[0071] 1, 2, 3, 11, 13, 21, 22, 31, 32, 41, 42, 43, 44, 45, 51, 52, 53, 60, 61, 62, 64 pipeline

[0072] A1~A3 Warm fluid passage

[0073] B1~B3 Cold fluid passage

[0074] a1, a2, a3 warm flow gas passages

[0075] a4, a5 warm fluid passage

[0076] b1~b3 Cold flow gas passage

[0077] b6 Cold fluid passage

[0078] C1 Product Oxygen

[0079] C2 Nitrogen

[0080] C3 Medium Pressure Nitrogen

[0081] C6 Liquid Oxygen

[0082] W1, W2, W3 raw air

[0083] W4 Container discharge

[0084] W5 Episiotomy Fluid

[0085] W6 Oxygen-enriched liquid air

[0086] W7 Liquid Nitrogen

Claims

1. A heat exchanger used in an air separation device having a low-pressure tower, a high-pressure tower and a mixing tower, characterized in that: The heat exchanger is constructed of plates and fins, and Used to cool the warm flow gas as at least a part of the raw air and at least one warm flow liquid taken out from the mixing tower by using at least one cold flow gas taken out from the low-pressure tower and the cold flow gas taken out from the mixing tower, and to heat the cold flow liquid taken out from the low-pressure tower via a booster pump and supplied to the mixing tower.

2. The heat exchanger according to claim 1, characterized in that: Used to cool at least one warm liquid stream taken out from the high-pressure column.

3. The heat exchanger according to claim 1 or 2, characterized in that: The invention comprises: a cold flow liquid passage for the cold flow liquid to flow; a cold flow gas passage for the cold flow gas to flow; a warm flow liquid passage for the warm flow liquid to flow; and a warm flow gas passage for the warm flow gas to flow, wherein the warm flow gas passage is configured such that the warm flow gas flows in a countercurrent manner relative to the cold flow liquid and the cold flow gas, and the warm flow liquid passage is configured such that the warm flow liquid flows in a cross-current manner relative to the cold flow liquid and the cold flow gas.

Images