Dehumidification system for carbon dioxide preparation

Abstract

The utility model relates to the technical field of carbon dioxide preparation, and provides a dehumidification system for carbon dioxide preparation, the dehumidification system is arranged between a three-stage compressor and a rectifying tower and is used for removing moisture in compressed carbon dioxide gas, and an outlet of the three-stage compressor is used for being connected with a tubular heat exchanger. The tubular heat exchanger comprises a first outlet for outputting low-temperature gas to the regeneration adsorption tower A, a second outlet for outputting separated water, and a third outlet connected with the low-temperature adsorption tower B; a gas outlet pipe of the regeneration adsorption tower A is communicated with the tubular heat exchanger through a return pipe; a waste heat pipeline of the three-stage compressor is connected with a regeneration auxiliary heating pipe of the regeneration adsorption tower A; a membrane separation assembly is arranged outside a gas outlet of the low-temperature adsorption tower B, and a gas outlet pipe of the membrane separation assembly is used for being connected with the rectifying tower. According to the utility model, the dehumidification effect of compressed carbon dioxide gas is improved; meanwhile, the utilization rate of energy in the system is increased, and the energy consumption of the system is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide preparation, in particular to a dehumidification system for carbon dioxide preparation. BACKGROUND

[0002] In the process of carbon dioxide preparation, the raw gas is treated by multi-stage compression, that is, the raw gas is first introduced into a desulfurization tower after two-stage compression for desulfurization treatment, and then the raw gas is compressed again after desulfurization, and only after three-stage compression, the purified carbon dioxide is introduced into a rectification tower for rectification to obtain pure carbon dioxide gas, which is then liquefied into liquid carbon dioxide by a liquefier and stored. In this process, the water content in the carbon dioxide gas after multi-stage compression affects the purity of the final carbon dioxide, so a dehumidifier adsorption tower is usually designed to remove water. However, in the existing dehumidification system, the dehumidification effect and the overall energy consumption of the system are proportional, that is, the more efficient the dehumidification, the higher the energy consumption of the system, which cannot achieve a win-win situation.

[0003] Therefore, the present application provides a dehumidification system for carbon dioxide preparation. CONTENT

[0004] The dehumidification system for carbon dioxide preparation provided by the present application solves the technical problem that the existing dehumidification system cannot achieve efficient dehumidification with low energy consumption.

[0005] Specifically, the dehumidification system for carbon dioxide preparation provided by the present application is arranged between a three-stage compressor and a rectification tower, and is used to remove water from the compressed carbon dioxide gas. The outlet of the three-stage compressor is connected to a tubular heat exchanger, and the tubular heat exchanger includes a first outlet for outputting low-temperature gas to a regeneration adsorption tower A, a second outlet for outputting precipitated water, and a third outlet for connecting to a low-temperature adsorption tower B. The gas outlet pipe of the regeneration adsorption tower A is in communication with the tubular heat exchanger through a reflux pipe, and the waste heat pipe of the three-stage compressor is connected to the regeneration auxiliary heat pipe of the regeneration adsorption tower A. The low-temperature adsorption tower B is externally provided with a membrane separation assembly, and the gas outlet pipe of the membrane separation assembly is connected to the rectification tower.

[0006] Optionally, the regeneration adsorption tower A is internally provided with a heater and a plurality of layers of silica gel adsorption beds, and adjacent adsorption beds are supported by plastic mesh plates. The heater is externally connected to a heat dissipation pipe arranged along the direction of the tower body, and the heat dissipation pipe includes a plurality of heat dissipation holes.

[0007] Optionally, the low-temperature adsorption tower B uses molecular sieve to adsorb water.

[0008] Optionally, a controller, a first electronic valve and a second electronic valve are further included, the first electronic valve is connected with an outlet pipe of the first outlet, the second electronic valve is arranged between the low-temperature adsorption tower B and the membrane separation assembly, and the controller is in signal connection with the first electronic valve and the second electronic valve.

[0009] Optionally, the membrane separation assembly comprises a polyimide film, a film-coated plate and a liquid-accumulating pipe, the polyimide film is attached to the film-coated plate, the film-coated plate is provided with a flow guide groove, and the film-coated plate is inserted on the liquid-accumulating pipe in an inclined manner.

[0010] Optionally, the liquid-accumulating pipe corresponds to the film-coated plate one by one, and a plurality of the liquid-accumulating pipes are arranged in a same height.

[0011] Optionally, the front surface and the back surface of the film-coated plate are both attached with the polyimide film.

[0012] The principle and beneficial effects of the present application are as follows:

[0013] In the dehumidification system for carbon dioxide preparation provided by the present application, a three-stage coupling dehumidification system is formed by a tubular heat exchanger, a regeneration adsorption tower A and a low-temperature adsorption tower B, so that the dehumidification effect of the carbon dioxide gas after compression treatment is improved; meanwhile, the waste heat of the three-stage compressor and the waste heat of the tubular heat exchanger are used to heat the regeneration adsorption tower, so that the energy utilization rate in the system is improved and the energy consumption of the system is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 Fig. 1 shows a structural schematic diagram of the dehumidification system for carbon dioxide preparation provided by the present application;

[0015] Figure 2 Fig. 4 shows a cross-sectional schematic diagram of the regeneration adsorption tower in the present application;

[0016] Figure 3 Fig. 5 shows an internal structural schematic diagram of the membrane separation assembly in the present application.

[0017] 1: three-stage compressor; 2: rectifying tower; 3: tubular heat exchanger; 4: membrane separation assembly; 41: polyimide film; 42: film-coated plate; 43: liquid-accumulating pipe; 5: silica gel adsorption bed; 6: heat dissipation pipe; 7: first electronic valve; 8: second electronic valve. DETAILED DESCRIPTION

[0018] The technical solutions in the application examples will be clearly and completely described below with reference to the drawings in the application examples. In addition, "in an embodiment" or "in an embodiment" appearing at various places in the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in any suitable manner in one or more embodiments. DETAILED DESCRIPTION

[0019] It is also important to note that the terms "first" and "second" and similar such relational terms are used solely to distinguish one from another entity without necessarily requiring or implying any such actual relationship or order between such entities. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process or method. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process or method.

[0020] In the carbon dioxide preparation process, the raw gas is subjected to multi-stage compression treatment, that is, the raw gas is first subjected to two-stage compression and then introduced into a desulfurization tower for desulfurization treatment, and after the desulfurization is qualified, the raw gas is subjected to compression treatment again, and after three-stage compression, the purified carbon dioxide is introduced into a rectification tower 2 for rectification to obtain pure carbon dioxide gas, which is liquefied into liquid carbon dioxide by a liquefier and then stored. In the process, the water content in the carbon dioxide gas after multi-stage compression affects the purity of the final carbon dioxide, so a dehumidifier adsorption tower is commonly used to remove water. However, in the existing dehumidification system, the dehumidification effect and the overall energy consumption of the system are proportional, that is, the more efficient the dehumidification, the higher the energy consumption of the system, which cannot be a win-win situation. Therefore, the utility model provides a dehumidification system for carbon dioxide preparation.

[0021] The device selects medium-pressure method to produce liquid carbon dioxide. According to the thermodynamic conditions of the carbon dioxide phase diagram, as long as the pure carbon dioxide can maintain the conditions of the carbon dioxide liquefaction zone of 2.1 MPa and -20 DEG C, liquid carbon dioxide can be obtained. Since the raw material gas of the device is at normal pressure, the carbon dioxide purity is 98 %, and the rest is non-condensable gas, so the raw material gas carbon dioxide needs to be compressed by three-stage oil-free lubrication to raise the final pressure to 2.7 MPa, evaporated at -25 DEG C to -30 DEG C, and the compressed carbon dioxide gas is indirectly cooled to -20 DEG C to be liquefied. The selected compressor is two 11.5-4DF-F3-NL 135 / 30 type compressors.

[0022] This utility model provides a dehumidification system for carbon dioxide production. The dehumidification system is located between a three-stage compressor 1 and a distillation column 2 to remove moisture from the compressed carbon dioxide gas. The outlet of the three-stage compressor 1 is connected to a tubular heat exchanger 3. The tubular heat exchanger 3 includes a first outlet for outputting low-temperature gas to a regeneration adsorption column A, a second outlet for outputting precipitated moisture, and a third outlet for connecting to a low-temperature adsorption column B. The outlet pipe of the regeneration adsorption column A is connected to the tubular heat exchanger 3 through a reflux pipe. The waste heat pipeline of the three-stage compressor 1 is connected to the regeneration auxiliary heat pipe of the regeneration adsorption column A. A membrane separation component 4 is provided outside the outlet of the low-temperature adsorption column B, and the outlet pipe of the membrane separation component 4 is connected to the distillation column 2.

[0023] As described above, the dehumidification system for carbon dioxide preparation provided by this utility model utilizes a three-stage coupled dehumidification system consisting of a tubular heat exchanger 3, a regeneration adsorption tower A, and a low-temperature adsorption tower B, which improves the dehumidification effect of the compressed carbon dioxide gas. At the same time, the waste heat from the three-stage compressor 1 and the waste heat from the tubular heat exchanger 3 are used to heat the regeneration adsorption tower A, which improves the energy utilization rate of the system and reduces the energy consumption of the system.

[0024] Specifically, such as Figure 1 As shown in the diagram, numbers ①②③ represent the pipes corresponding to the first, second, and third outlets, respectively. The dehumidification principle and process of the aforementioned three-stage coupled dehumidification system are as follows:

[0025] First, the compressed raw gas is condensed and dehydrated in the tubular heat exchanger 3:

[0026] A swirl-tube heat exchanger 3 is installed at the outlet of the three-stage compressor 1. Cooling water (or refrigerant) is used to pre-cool the high-temperature, high-pressure raw gas, reducing its temperature to below 20°C or 10°C-15°C. This causes most of the free water to condense and precipitate, with the precipitated water flowing out from the second outlet. Advantages: Reduces subsequent adsorption load and recovers waste heat for regeneration.

[0027] Then, temperature-switched adsorption in the dual adsorption towers:

[0028] Among them, regeneration adsorption tower A is a high-temperature tower, and low-temperature adsorption tower B is a low-temperature tower. Regeneration adsorption tower A receives the low-temperature gas from the first outlet of tubular heat exchanger 3 and heats it using the waste heat from the compressor. After heating, the gas flows along the reflux pipe ( Figure 1 The gas (represented by the dashed line in Chinese characters) is returned to the tubular heat exchanger 3 for further cooling. The treated gas is then discharged from the third outlet into the low-temperature adsorption tower B. Utilizing the principle that molecular sieves have better adsorption effects at low temperatures than at room or high temperatures, the gas is used to remove moisture from the carbon dioxide gas to the maximum extent. Specifically, the low-temperature adsorption tower B uses molecular sieves to adsorb moisture, while the regeneration adsorption tower A contains a multi-layer silica gel adsorption bed 5 to adsorb moisture.

[0029] Finally, membrane separation component 4 is used to assist in dehydration:

[0030] Polyimide membrane 41 is a hollow fiber membrane, and its permeation rate for carbon dioxide and water differs significantly, with its permeation rate for water being much greater than its permeation rate for carbon dioxide.

[0031] In addition, the waste heat from the compressor in the regeneration adsorption tower A heats the temperature inside the tower to 80℃-100℃. At this temperature, the silica gel adsorption bed 5 is regenerated, and the regenerated gas is returned to the tubular heat exchanger 3 to recover moisture.

[0032] In addition, this utility model also includes a controller, a first electronic valve 7, and a second electronic valve 8. The first electronic valve 7 is connected to the outlet pipe of the first outlet, and the second electronic valve 8 is located between the low-temperature adsorption tower B and the membrane separation component 4. The controller is signal-connected to the first electronic valve 7 and the second electronic valve 8. The controller intelligently controls the opening and closing of the first electronic valve 7 and the second electronic valve 8 to automatically control the adsorption process in the regeneration adsorption tower A and the dehumidification process in the membrane separation component 4, respectively. In this embodiment, the method of controller control of the two electronic valves is not specifically limited; relevant existing control technologies can be referred to. Of course, the system also includes other related control valves, such as... Figure 1 The other control valves shown are similar to the first and second control valves, and will not be described again in this embodiment.

[0033] It should be noted that the energy recycling process in this utility model includes:

[0034] Firstly, the waste heat from the three-stage compressor 1 provides a heat source for the regeneration adsorption tower A;

[0035] Secondly, the heat (condensation heat) generated by the tubular heat exchanger 3 is fed into the regeneration adsorption tower A for the evaporation of moisture in the regeneration gas.

[0036] Third, the low-pressure side gas in membrane separation component 4 is returned to the three-stage compressor 1 for recirculation. Because a certain pressure environment is required during membrane separation, low pressure will affect the separation effect of membrane separation component 4 and may lead to incomplete water separation. Therefore, it is circulated back to the three-stage compressor 1 for recirculation to improve the overall dehumidification and drying quality of the system.

[0037] In some embodiments, the aforementioned regeneration adsorption tower A is further equipped with a heater, and adjacent adsorption beds are supported by plastic mesh plates. A heat dissipation pipe 6, arranged along the tower body direction, is connected externally to the heater, and the heat dissipation pipe 6 includes several heat dissipation holes. In this embodiment, the heater is used to assist in heating the tower body. Considering that the waste heat from the compressor is insufficient to heat the tower body to the target temperature of 100°C, the heater is used to heat the gas inside the tower.Figure 2 As shown, in order to uniformly heat the gas in the tower body, heat dissipation pipes 6 are arranged along the length direction of the tower body, and the heated gas diffuses along the heat dissipation pipes 6 to the silica gel adsorption bed 5 in the tower.

[0038] In some embodiments, as Figure 3 As shown, the aforementioned membrane separation assembly 4 includes a polyimide membrane 41, a coated plate 42, and a liquid accumulation pipe 43, the polyimide membrane 41 is attached to the coated plate 42, the coated plate 42 is provided with flow guide grooves (such as Figure 3 a strip-shaped groove shown after the polyimide membrane 41 is cut in the middle), and the coated plate 42 is obliquely inserted into the liquid accumulation pipe 43. The moisture permeated by the polyimide membrane 41 is left to the liquid accumulation pipe 43 along the flow guide grooves on the coated plate 42, and the liquid accumulation pipe 43 guides the filtered moisture out. It can also be implemented that the flow guide grooves are arranged in a grid shape at equal intervals to increase the hydrophobicity of the coated plate 42.

[0039] In other embodiments, the liquid accumulation pipe 43 corresponds to the coated plate 42 one by one, and a plurality of the liquid accumulation pipes 43 are arranged at the same height. In this embodiment, one liquid accumulation pipe 43 corresponds to one coated plate 42, and the liquid accumulation pipe 43 is obliquely installed and fixed to improve the efficiency of draining water.

[0040] In other embodiments, the front and back surfaces of the coated plate 42 are attached with the polyimide membrane 41. In this embodiment, the polyimide membrane 41 is attached on both sides of the coated plate 42 to increase the efficiency of the membrane separation assembly 4 in separating the water in the carbon dioxide.

[0041] In summary, the present application utilizes the waste heat of the equipment in the system in multiple directions, reduces the energy consumption of the system, and at the same time realizes the removal of water in the raw gas by the system, so that the moisture content of the treated carbon dioxide gas is in the range of 0.5% to 5%.

[0042] It should be noted that each of the above embodiments belongs to the same inventive concept, and the description of each embodiment has its own emphasis. If the description is not exhaustive in some embodiments, it can be referred to the description in other embodiments. Each embodiment in the specification is described in a progressive manner, and each embodiment emphasizes the difference from other embodiments. The same or similar parts between each embodiment can be referred to each other.

[0043] The above embodiments only express the implementation of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the utility model patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, some modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the utility model patent should be subject to the appended claims.

Claims

1. A dehumidification system for carbon dioxide production, said dehumidification system being disposed between a three-stage compressor (1) and a distillation column (2) for removing moisture from compressed carbon dioxide gas, characterized in that, The outlet of the three-stage compressor (1) is used to connect to the tubular heat exchanger (3), which includes a first outlet for outputting low-temperature gas to the regeneration adsorption tower A, a second outlet for outputting precipitated water, and a third outlet for connecting to the low-temperature adsorption tower B. The outlet pipe of the regeneration adsorption tower A is connected to the tubular heat exchanger (3) through a reflux pipe, and the waste heat pipeline of the three-stage compressor (1) is connected to the regeneration auxiliary heat pipe of the regeneration adsorption tower A. A membrane separation component (4) is provided outside the outlet of the low-temperature adsorption tower B, and the outlet pipe of the membrane separation component (4) is used to connect to the distillation tower (2).

2. The dehumidification system for carbon dioxide production according to claim 1, characterized in that, The regeneration adsorption tower A is equipped with a heater and a multi-layer silica gel adsorption bed (5). Adjacent adsorption beds are supported by plastic mesh plates. The heater is connected to a heat dissipation pipe (6) arranged along the tower body. The heat dissipation pipe (6) includes several heat dissipation holes.

3. The dehumidification system for carbon dioxide production according to claim 2, characterized in that, The low-temperature adsorption tower B uses molecular sieves to adsorb moisture.

4. The dehumidification system for carbon dioxide production according to claim 3, characterized in that, It also includes a controller, a first electronic valve (7) and a second electronic valve (8). The first electronic valve (7) is connected to the outlet pipe of the first outlet, and the second electronic valve (8) is located between the low-temperature adsorption tower B and the membrane separation assembly (4). The controller is signal-connected to the first electronic valve (7) and the second electronic valve (8).

5. The dehumidification system for carbon dioxide production according to claim 1, characterized in that, The membrane separation assembly (4) includes a polyimide membrane (41), a membrane plate (42), and a liquid collection tube (43). The polyimide membrane (41) is attached to the membrane plate (42), and the membrane plate (42) is provided with a flow guide groove. The membrane plate (42) is obliquely inserted into the liquid collection tube (43).

6. The dehumidification system for carbon dioxide production according to claim 5, characterized in that, The liquid collection tubes (43) correspond one-to-one with the film plate (42), and the multiple liquid collection tubes (43) are arranged at the same height.

7. The dehumidification system for carbon dioxide production according to claim 5, characterized in that, The polyimide film (41) is attached to both the front and back of the laminated plate (42).

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