A multi-section heat exchanger

Abstract

A multi-section heat exchanger, comprising an exhaust flue, a first jacket section, a second jacket section, a transition section, and a plurality of heat pipes, the first jacket section is sleeved on an upstream section of the exhaust flue, the second jacket section is sleeved on a middle section of the exhaust flue, the transition section is connected with the exhaust flue in parallel, a downstream section is connected with a medium inlet of the first jacket section, heat absorbing ends of the plurality of heat pipes are located in the downstream section of the exhaust flue, heat releasing ends of the heat pipes are located in an upstream section of the transition section, and the heat releasing end of each heat pipe is higher than the heat absorbing end. The utility model discloses simple structure, low processing cost can utilize exhaust waste heat efficiently, satisfies the actual demand of enterprise.

Description

Technical Field

[0001] This utility model relates to the chemical industry, and in particular to a multi-stage heat exchanger. Background Technology

[0002] Chemical companies use natural gas and sulfur as raw materials to produce carbon disulfide. Specifically, the raw natural gas is heated to about 400°C in the preheating section of the heating furnace. It is then mixed with liquid sulfur (about 140°C) from the underground liquid sulfur tank in a static mixer (about 220°C). The mixture is then heated to about 650°C in the heating section of the heating furnace, and finally enters an adiabatic reactor to complete the reaction and produce carbon disulfide as a product and hydrogen sulfide as a byproduct.

[0003] The heating furnace utilizes a flue gas induced draft fan to draw negative pressure, drawing ambient air into the furnace chamber to burn with the fuel natural gas. This heats the raw materials, natural gas and sulfur, within the furnace tubes. The resulting flue gas (around 750°C) is cooled to approximately 150°C through heat exchange with soft water in the furnace steam drum, and then discharged through the chimney by the induced draft fan. The soft water in the furnace steam drum is heated by the flue gas into 0.8MPa steam for the unit's use; any excess steam is vented, resulting in waste.

[0004] To improve energy efficiency, the current method involves installing two heat exchangers connected in series, utilizing the waste heat from the exhaust gas of the tubular furnace as the heating medium. The upstream heat exchanger is used to raise the inlet air temperature, and the downstream heat exchanger is used to raise the soft water temperature. While this heat exchange structure can utilize exhaust waste heat, its utilization rate cannot meet the company's needs, and its layout is inconvenient.

[0005] Therefore, designing a heat exchanger with a compact structure and high utilization rate of exhaust waste heat is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a multi-stage heat exchanger with a simple structure, low processing cost, and efficient utilization of exhaust waste heat to meet the actual needs of enterprises.

[0007] The technical solution of this utility model is: a multi-stage heat exchanger, including an exhaust flue, a first jacket section, a second jacket section, a transition section, and a plurality of heat pipes. The first jacket section is fitted in the upstream section of the exhaust flue, the second jacket section is fitted in the middle section of the exhaust flue, the transition section is connected in parallel with the exhaust flue, and the downstream section is connected to the medium inlet of the first jacket section. The heat absorption ends of the plurality of heat pipes are located in the downstream section of the exhaust flue, and the heat release ends of these heat pipes are located in the upstream section of the transition section, and the heat release ends of each heat pipe are higher than the heat absorption ends.

[0008] The heat pipes are arranged in parallel intervals, and the tilt angle of each heat pipe is 3-5°.

[0009] The exhaust flue and transition section both extend vertically, with the upstream section of the exhaust flue located above the downstream section and the upstream section of the transition section located below the downstream section. The upstream section of the transition section is flush with the downstream section of the exhaust flue.

[0010] The media inlet of the first jacket section is located below the media outlet, and the media inlet of the second jacket section is located below the media outlet.

[0011] The downstream section of the transition section is connected to the medium outlet of the first jacket section via a first short pipe section, on which a first valve is installed.

[0012] The upstream section of the exhaust flue is connected to the downstream section of the exhaust flue via a second short connecting pipe section, on which a second valve is installed.

[0013] The above technical solution has the following beneficial effects:

[0014] 1. The multi-stage heat exchanger includes an exhaust flue, a first jacket section, a second jacket section, a transition section, and several heat pipes. The upstream section of the exhaust flue is connected to the exhaust gas source, allowing the high-temperature exhaust gas to be sent to the exhaust gas treatment system, fully utilizing the heat contained in the exhaust gas. The first jacket section is installed in the upstream section of the exhaust flue, and the second jacket section is installed in the middle section of the exhaust flue. That is, the first and second jacket layers are located in the upstream and middle sections of the exhaust flue, respectively, exchanging heat with the exhaust gas within the exhaust flue. Through the first and second jacket layers, a stepped heat exchange is performed on the exhaust gas within the exhaust flue, which not only improves the utilization rate of the exhaust gas heat but also allows for preheating of different process media through the first and second jacket layers, avoiding the risk of pipeline damage due to violent boiling caused by drastic temperature rise of the process media, thus meeting the actual needs of enterprises. The transition section is connected in parallel with the exhaust flue, and the downstream section is connected to the medium inlet of the first jacket section. The heat-absorbing ends of several heat pipes are located in the downstream section of the exhaust flue, and the heat-releasing ends of these heat pipes are located in the upstream section of the transition section. The heat-releasing ends of each heat pipe are higher than the heat-absorbing ends. After the exhaust gas undergoes two-stage heat exchange, it is discharged into the downstream section of the exhaust flue. The phase change medium in the heat-absorbing end of each heat pipe absorbs heat and transfers the heat to the heat-releasing end, preheating it before sending it to the process medium in the first jacket section, further improving the heat utilization rate of the exhaust gas.

[0015] 2. The heat pipes are arranged in parallel intervals, and the tilt angle of each heat pipe is 3-5°, which improves the heat utilization rate of the exhaust gas after the two-stage heat exchange and ensures the normal operation of each heat pipe.

[0016] 3. The medium inlet of the first jacket section is located below the medium outlet, and the medium inlet of the second jacket section is located below the medium outlet, thereby improving the heat exchange efficiency of the process medium in the first and second jacket sections.

[0017] 4. The downstream section of the transition section is connected to the medium outlet of the first jacket section through the first short pipe section, which is equipped with a first valve. The upstream section of the exhaust flue is connected to the downstream section of the exhaust flue through the second short pipe section, which is equipped with a second valve. The first valve and the second valve can be closed or opened as needed to allow the process medium to skip the heat exchange stage and meet the actual needs of the enterprise.

[0018] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] In the attached diagram, 1 is the first jacket section, 2 is the second jacket section, 3 is the exhaust flue, 4 is the transition section, 5 is the heat pipe, 6 is the first short pipe section, 7 is the second short pipe section, a is the first valve, and b is the second valve. Detailed Implementation

[0021] See Figure 1 This is a specific embodiment of a multi-stage heat exchanger. The multi-stage heat exchanger includes an exhaust flue 3, a first jacket section 1, a second jacket section 2, a transition section 4, and several heat pipes 5. Specifically, the exhaust flue 3 and the transition section 4 both extend vertically, with the upstream section of the exhaust flue 3 located above the downstream section and the upstream section of the transition section 4 located below the downstream section. The upstream section of the transition section 4 is flush with the downstream section of the exhaust flue 3. The first jacket section 1 is fitted onto the upstream section of the exhaust flue 3, and the second jacket section 2 is fitted onto the middle section of the exhaust flue 3. In this embodiment, the medium inlet of the first jacket section 1 is located below the medium outlet, and the medium inlet of the second jacket section 2 is located below the medium outlet. The transition section 4 is connected in parallel with the exhaust flue 3, and its downstream section is connected to the medium inlet of the first jacket section 1. The heat absorption ends of several heat pipes 5 are located in the downstream section of the exhaust flue 3, and the heat release ends of these heat pipes 5 are located in the upstream section of the transition section 4. The heat release ends of each heat pipe are higher than the heat absorption ends. Specifically, the heat pipes 5 are arranged in parallel intervals, and the inclination angle of each heat pipe is 3-5°.

[0022] Furthermore, in order to meet the actual needs of the enterprise, the downstream section of the transition section 4 is connected to the medium outlet of the first jacket section 1 through the first short pipe section 6, and the first short pipe section 6 is equipped with a first valve a. The upstream section of the exhaust flue 3 is connected to the downstream section of the exhaust flue 3 through the second short pipe section 7, and the second short pipe section 7 is equipped with a second valve b.

[0023] The working principle of this utility model is as follows: Taking the flue gas from the heating furnace as the heat exchange gas, and preheating the inlet air and soft water in the boiler drum of the heating furnace as an example, the soft water in the boiler drum enters the second jacket section through the medium inlet and is discharged to the boiler drum through the medium outlet of the second jacket section. The combustion air used in the heating furnace enters the first jacket section through the upstream end of the transition section and the medium inlet of the first jacket section, and is sent to the furnace chamber of the heating furnace through the medium outlet of the first jacket section. The flue gas (around 750°C) generated by the heating furnace is discharged to the tail gas treatment system through the upstream, middle, and downstream sections of the exhaust flue. During the emission process, the flue gas exchanges heat with the combustion air in the first jacket section in the upstream section, exchanges heat with the soft water in the second jacket section in the middle section, and releases heat to each heat pipe in the downstream section. Simultaneously, the combustion air is preheated by each heat pipe in the upstream section of the transition section, and enters the furnace chamber of the heating furnace after being heated in the first jacket section. The soft water is heated in the second jacket section and then sent to the boiler drum of the heating furnace.

Claims

1. A multi-stage heat exchanger, characterized in that: It includes an exhaust flue (3), a first jacket section (1), a second jacket section (2), a transition section (4), and several heat pipes (5). The first jacket section (1) is fitted onto the upstream section of the exhaust flue (3), the second jacket section (2) is fitted onto the middle section of the exhaust flue (3), the transition section (4) is connected in parallel with the exhaust flue (3), and its downstream section is connected to the medium inlet of the first jacket section (1). The heat-absorbing ends of several heat pipes (5) are located in the downstream section of the exhaust flue (3), and the heat-releasing ends of these heat pipes (5) are located in the upstream section of the transition section (4), with the heat-releasing end of each heat pipe higher than the heat-absorbing end.

2. The multi-stage heat exchanger according to claim 1, characterized in that: The heat pipes (5) are arranged in parallel intervals, and the tilt angle of each heat pipe is 3-5°.

3. The multi-stage heat exchanger according to claim 1, characterized in that: The exhaust flue (3) and the transition section (4) both extend vertically, with the upstream section of the exhaust flue (3) located above the downstream section and the upstream section of the transition section (4) located below the downstream section. The upstream section of the transition section (4) is flush with the downstream section of the exhaust flue (3).

4. The multi-stage heat exchanger according to claim 3, characterized in that: The medium inlet of the first jacket section (1) is located below the medium outlet, and the medium inlet of the second jacket section (2) is located below the medium outlet.

5. The multi-stage heat exchanger according to claim 1, characterized in that: The downstream section of the transition section (4) is connected to the medium outlet of the first jacket section (1) through the first short pipe section (6), and the first short pipe section (6) is provided with a first valve (a).

6. The multi-stage heat exchanger according to claim 1, characterized in that: The upstream section of the exhaust flue (3) is connected to the downstream section of the exhaust flue (3) through a second short pipe section (7), on which a second valve (b) is provided.

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