Carbon dioxide combined dehydration system

Abstract

The utility model discloses a carbon dioxide combined dehydration system, which relates to the field of carbon dioxide dehydration and comprises a dehydration line of a filter separator, a freezing dryer, a first separator, a dehydration tower and an outlet filter which are sequentially connected. The regeneration line is connected to the output end of the dehydration line and is communicated with a compressor; the compressor is communicated with a cold medium inlet of a heat exchanger; a hot medium outlet of the heat exchanger is communicated with a heater; the heater is communicated with a bottom inlet of a regeneration tower; and the condenser is connected with the second separator. The dehydration mode that low-temperature pre-cooling is conducted firstly, separation is conducted firstly, and then fine dehydration is conducted is adopted, the dehydration depth is higher, regenerated gas is taken from dehydrated purified gas, and the drying capacity is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon dioxide dehydration, and more specifically to a carbon dioxide combined dehydration system. Background Art

[0002] In the collection of oil, carbon dioxide flooding is a technology for improving crude oil recovery that has been developed and applied in recent years. This technology has obvious advantages in improving the recovery rate of high water content and low permeability and ultra-low permeability reservoirs. It mainly improves the recovery rate through the mechanism that carbon dioxide expands and reduces viscosity after dissolving in crude oil, and reduces interfacial tension when mixed with crude oil under certain conditions, thereby improving the efficiency of oil recovery. At the same time, a large amount of carbon dioxide can be buried underground, which plays a role in reducing greenhouse gas emissions. When the captured carbon dioxide is used in the process of oil recovery, it is necessary to deeply dehydrate the carbon dioxide in order to meet industrial needs.

[0003] The patent document with the publication number CN218290822U in the prior art discloses a natural gas dehydration system using system pressure regeneration, including: a molecular sieve dehydration tower, a molecular sieve regeneration tower, a filter separator, a first regulating valve, an outlet filter, a second regulating valve, a flow meter, a heat exchanger and a heater; the filter separator, the first regulating valve, the molecular sieve dehydration tower and the outlet filter are connected in sequence through pipelines, and natural gas flows in sequence therein to form a molecular sieve dehydration circuit; the inlet of the second regulating valve is connected to the outlet of the filter separator for inputting regeneration gas, and the second regulating valve, the flow meter, the heat exchanger, the heater and the molecular sieve regeneration tower are connected in sequence through pipelines, and the regeneration gas flows in sequence therein to form a molecular sieve drying circuit. In actual use, the dehydration depth is insufficient only by direct dehydration through the molecular sieve, and the regeneration gas is taken from the raw gas, which has not been dehydrated, has a high water content, and has insufficient drying capacity. Utility Model Content

[0004] In order to overcome the defects in the above-mentioned prior art, the utility model discloses a carbon dioxide combined dehydration system with low-temperature precooling and then dehydration. The purpose of the utility model is to solve the problems of insufficient dehydration depth and weak regeneration capacity in the prior art.

[0005] In order to achieve the above objectives, the technical solution adopted by the utility model is:

[0006] A carbon dioxide combined dehydration system comprises a dehydration circuit and a regeneration circuit, wherein the dehydration circuit comprises a filter separator, a dehydration tower and an outlet filter connected in sequence through pipelines, and is characterized in that: the dehydration circuit is further connected to a pre-dehydration circuit through a pipeline between the filter separator and the dehydration tower, and a cold dryer and a first separator are arranged in sequence on the pre-dehydration circuit; the regeneration circuit is provided with a compressor, a heat exchanger, a heater, a regeneration tower, a condenser and a second separator, the regeneration circuit input end is connected to the output end of the dehydration circuit, the compressor outlet is connected to the heat exchanger cold medium inlet through a pipeline, the heat exchanger hot medium outlet is connected to the heater inlet, the heater outlet is connected to the regeneration tower bottom inlet, the regeneration tower top outlet is connected to the heat exchanger hot medium inlet, the heat exchanger cold medium outlet is connected to the condenser inlet, and the condenser outlet is connected to the second separator inlet.

[0007] Furthermore, the cooling temperature of the cold dryer is 15°C.

[0008] Furthermore, the heater has a heating range of 220 to 280°C.

[0009] Furthermore, the condenser cooling temperature is 45°C.

[0010] Furthermore, the compressor increases the regeneration gas pressure to 0.05~0.1MPa greater than the inlet pressure.

[0011] Furthermore, the exhaust port of the second separator is connected to the air inlet of the dehydration tower.

[0012] Furthermore, it also includes a first inlet and outlet tower valve group and a second inlet and outlet tower valve group, and the inlet and outlet gases of the dehydration tower and the regeneration tower are connected to external equipment through the first inlet and outlet tower valve group and the second inlet and outlet tower valve group.

[0013] Furthermore, the dehydration tower, the regeneration tower, the first separator and the second separator are all connected to a sewage pipe.

[0014] Furthermore, the dehydration tower and the regeneration tower are operated in an alternating dehydration and regeneration process, and the opening and closing states of the control valves with the same functions arranged on the dehydration tower and the regeneration tower are opposite.

[0015] Furthermore, a first venting pipeline is connected between the filter separator and the cold dryer, and a second venting pipeline is connected to both the dehydration tower and the regeneration tower.

[0016] Beneficial effects of the utility model:

[0017] 1. Compared with the prior art, a cold dryer and a gas-liquid separator are set in the gas inlet section of the dehydration tower to pre-cool and separate the saturated carbon dioxide at low temperature to remove free water, and then further dehydrate it through the molecular sieve set in the dehydration tower, effectively improving the dehydration depth.

[0018] 2. In the utility model, the regenerated gas is taken from the purified gas after dehydration. The purified gas is "dry gas" with less water content. Under the same conditions, the "dry gas" can absorb more water vapor. The regenerated gas is heated and passed into the dehydration tower from bottom to top, which can remove the adsorbed substances near the inlet end of the dehydration tower and evaporate the medium adsorbed by the molecular sieve, so that the desiccant at the bottom can be regenerated.

[0019] 3. In the utility model, the adsorption amount of the molecular sieve in the dehydration tower is fixed. In the set process, a cold dryer is initially added to reduce the temperature of the raw gas to the set temperature. By lowering the temperature, the water content of the gas is greatly reduced, thereby greatly reducing the filling amount of the molecular sieve and reducing the corresponding equipment volume and optimizing the entire linked process equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the utility model;

[0021] Reference numerals:

[0022] 1. Instrument module; 2. Filter separator; 3. First venting pipeline; 4. Cold dryer; 5. First separator; 6. Dehydration tower; 7. Regeneration tower; 8. Regeneration tower control valve I; 9. Regeneration tower control valve II; 10. Dehydration tower control valve I; 11. Dehydration tower control valve II; 12. Regeneration tower control valve II; 13. Regeneration tower control valve I; 14. Dehydration tower control valve II; 15. Dehydration tower control valve I; 16. Second venting pipeline; 17. Heater; 18. Condenser; 19. Heat exchanger; 20. Second separator; 21. Outlet filter; 22. Compressor. DETAILED DESCRIPTION

[0023] The concept, specific structure and technical effects of the present invention will be clearly and completely described below in combination with the embodiments and drawings to fully understand the purpose, features and effects of the present invention.

[0024] There are three methods for gas dehydration: physical absorption, solvent absorption, and chemical reaction. Due to the property of carbon dioxide dissolving in water to form carbonic acid, it is difficult to handle the absorbed solvent later, and the same is true for the chemical reaction method. This process uses molecular sieve physical adsorption to remove water to a certain depth, and then regenerate the physical adsorbent. This can achieve the reuse of equipment and devices to obtain a higher dew point. It can be fully automatically operated in conjunction with the control system during operation to meet the needs of industrial production.

[0025] Example 1

[0026] like Figure 1As shown, the utility model provides a carbon dioxide combined dehydration system, including a dehydration tower and a regeneration tower, wherein the hollow part inside the dehydration tower is provided with a molecular sieve adsorbent, and also includes a dehydration line and a regeneration line, wherein the dehydration line includes a filter separator 2, a cold dryer 4, a first separator 5, a dehydration tower 6 and an outlet filter 21 connected in sequence; the regeneration line is connected to the outlet filter 21 on the dehydration line, and the regeneration gas is taken from the purified gas, and the regeneration gas pipeline is connected to a compressor 22, the compressor 22 is connected to the cold medium inlet of the heat exchanger 19, the hot medium outlet of the heat exchanger 19 is connected to the heater 17, the heater 17 is connected to the bottom air inlet of the regeneration tower 7, the top exhaust port of the regeneration tower 7 is connected to the hot medium inlet of the heat exchanger 19, the cold medium outlet of the heat exchanger 19 is connected to the condenser 18, and the condenser 18 is connected to the second separator 20. The regeneration gas is taken from the purified gas after dehydration, and the purified gas is "dry gas". Carbon dioxide is dissolved in water. When the "dry gas" reaches a saturated state, it can absorb more water on the evaporated molecular sieve adsorbent, and the drying capacity can be improved under the same conditions. The heated regenerated gas is passed into the dehydration tower from bottom to top, which can evaporate the medium adsorbed by the molecular sieve, so that the desiccant at the bottom can be regenerated, and the adsorbed substances near the inlet end of the dehydration tower can be removed, killing two birds with one stone.

[0027] HYSYS software was used to simulate the physical properties of the raw gas in various states, and the water content of the physical properties in various states was compared. The temperature of the raw gas after the compressor is generally high. According to the relevant monographs and the simulation method of HYSYS software, the saturated water content at 40-50°C is: 10540mmg / Nm³, and the saturated water content at 15°C is: 1742mmg / Nm³. Finally, it was determined to use the process of low-temperature pre-cooling for separation before entering the molecular sieve for fine dehydration.

[0028] By setting a cold dryer 4 with a cooling temperature of 15°C and a first separator 5 in the gas inlet section of the dehydration tower, the saturated carbon dioxide is first pre-cooled and separated at low temperature to remove free water, and then further finely dehydrated by the molecular sieve set in the dehydration tower 6, effectively improving the dehydration depth. The adsorption capacity of the molecular sieve in the dehydration tower 6 is fixed. In the set process, the cold dryer 4 is initially added to reduce the temperature of the raw gas to the set temperature. After the temperature is reduced, the water content of the gas is greatly reduced, thereby greatly reducing the filling amount of the molecular sieve and reducing the corresponding equipment volume and the optimization of the entire linked process equipment.

[0029] The specific function of the above-mentioned dehydration line is realized as follows: first, the high-pressure incoming gas enters the filter separator 2 to remove free water, oil, etc., then enters the cold dryer 4 to reduce the incoming gas temperature and precipitate the contained liquid, and then the first separator 5 separates the precipitated liquid. The separated gas enters the bottom of the dehydration tower 6 along the pipeline through the opened dehydration inlet valve group. After being adsorbed by the molecular sieve adsorbent in the dehydration tower 6, the gas enters the outlet filter 21 from the dehydration outlet valve group opened at the top to be filtered into purified gas, and the purified gas is finally output to the downstream. The specific implementation principle of the above regeneration line is as follows: the regeneration gas is taken from the purified gas after dehydration, and is input into the compressor 22 through the regeneration pipeline connected to the rear section of the outlet filter 21 to increase the pressure to 0.05~0.1MPa greater than the inlet pressure. The cold medium regeneration gas is continuously preheated by the heat exchanger 19 and heated to 220~280℃ by the heater 17, and then enters the regeneration tower 7 from the bottom of the regeneration tower 7 through the regeneration inlet valve group in the open state. The gas flows from bottom to top, which can remove the adsorbed substances near the air inlet end and completely regenerate the desiccant at the bottom. Finally, the mixed moisture after adsorption is completely brought out from the bottom to the top, and is output from the top of the regeneration tower 7 to the above heat exchanger 19 from the regeneration outlet valve group in the open state. The hot medium mixed gas and the cold medium regeneration gas are continuously heat exchanged, and after the temperature is reduced, they are transported to the condenser 18 for further cooling to 45℃, and finally flow into the second separator 20 for gas-liquid separation.

[0030] As an implementation method of this embodiment, the dehydration tower 6, the regeneration tower 7, the first separator 5 and the second separator 20 are all connected to a sewage pipe, and the separated water enters the sewage pool through the sewage pipe for collection. The exhaust port of the second separator 20 is connected to the bottom inlet of the dehydration tower 6. The second separator 20 is a gas-liquid separator, and the saturated gas separated from the exhaust port enters the dehydration cycle again through the pipeline.

[0031] Example 2

[0032] This embodiment is further described on the basis of embodiment 1. Figure 1 As shown, at least two dehydration towers are provided, including a dehydration tower 6 and a regeneration tower 7 arranged in parallel, and the dehydration tower 6 and the regeneration tower 7 are operated in an alternating process. The system is also provided with a first outlet valve group and a second outlet valve group, and the inlet and outlet gases of the dehydration tower 6 and the regeneration tower 7 are connected to external equipment through the first inlet and outlet valve group and the second inlet and outlet valve group. The above valve groups control the pipeline opening and closing states of the regeneration line and the dehydration line respectively. The valve groups with the same functions set on the dehydration tower 6 and the regeneration tower 7 have opposite opening and closing states.

[0033] With reference to the projects introduced from home and abroad and the domestic applications in natural gas dehydration and economic considerations, a short cycle system (i.e., 8-hour system) is adopted. The advantages are a small number of molecular sieves to be loaded, small investment, and only two towers. Considering the improvement of the quality of molecular sieves, an 8-hour regeneration cycle system is adopted, and the double towers are cyclically operated within 24 hours. The regeneration heating time is set to 4.2 hours, the cold blowing time is set to 3.3 hours, and the remaining 0.5 hour is used for equipment inspection and repair. The inlet channels of the dehydration tower 6 and the regeneration tower 7 are controlled by the dehydration inlet control valve Ⅰ15 and the regeneration inlet control valve Ⅱ12 respectively, and the outlet channels of the dehydration tower 6 and the regeneration tower 7 are controlled by the dehydration outlet control valve Ⅰ10 and the regeneration outlet control valve Ⅱ9 respectively; after the process conversion, the inlet channels of the dehydration tower 6 and the regeneration tower 7 are controlled by the dehydration inlet control valve Ⅱ14 and the regeneration inlet control valve Ⅰ13 respectively, and the outlet channels of the dehydration tower 6 and the regeneration tower 7 are controlled by the dehydration outlet control valve Ⅱ11 and the regeneration outlet control valve Ⅰ8 respectively; when the dehydration tower 6 is performing the dehydration process, the regeneration tower 7 is performing the regeneration process, and when the dehydration tower 6 is performing the regeneration process, the regeneration tower 7 is performing the dehydration process. Since the valve groups of the two towers are connected in parallel, the regeneration valve group of the regeneration tower 7 is closed and the regeneration valve group of the dehydration tower 6 is opened, and vice versa.

[0034] Example 3

[0035] This embodiment further illustrates the present invention based on the above-mentioned Embodiment 1 and Embodiment 2. Figure 1 As shown, a first venting pipeline 3 is connected between the filter separator 2 and the cold dryer 4, and a second venting pipeline 16 is connected between the outlet valve group and the outlet filter 21 to ensure the safety of the dehydration process.

[0036] As an implementation method of this embodiment, the first separator 5, the second separator 20 and the filter separator 2 are all provided with on-site display liquid level gauges and liquid level transmitters, the two ends of the dehydration tower 6 and the regeneration tower 7 are provided with differential pressure indicators, the two ends of the outlet filter 21 are provided with differential pressure transmitters, and the gas inlet end of the filter separator 2 is provided with an instrument module 1. The above indicator transmitters are a safety guarantee for the entire dehydration process. When the medium is out of any medium parameter range, the station control system responsible for monitoring and control can know and take solutions.

[0037] The implementation methods of the present invention are described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalents or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A carbon dioxide combined dehydration system, comprising a dehydration line and a regeneration line, wherein the dehydration line comprises a filter separator (2), a dehydration tower (6) and an outlet filter (21) connected in sequence by pipelines, characterized in that: The dehydration line is provided with a pre-dehydration line between the filter separator (2) and the dehydration tower (6), and the pre-dehydration line comprises a cold dryer (4) and a first separator (5) connected in sequence; The regeneration line is provided with a compressor (22), a heat exchanger (19), a heater (17), a regeneration tower (7), a condenser (18) and a second separator (20); the input end of the regeneration line is connected to the output end of the dehydration line; the outlet of the compressor (22) is connected to the cold medium inlet of the heat exchanger (19) through a pipeline; the hot medium outlet of the heat exchanger (19) is connected to the inlet of the heater (17); the outlet of the heater (17) is connected to the bottom inlet of the regeneration tower (7); the top outlet of the regeneration tower (7) is connected to the hot medium inlet of the heat exchanger (19); the cold medium outlet of the heat exchanger (19) is connected to the inlet of the condenser (18); and the outlet of the condenser (18) is connected to the inlet of the second separator (20).

2. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The cooling temperature of the cold dryer (4) is 15°C.

3. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The heating range of the heater (17) is 220-280°C.

4. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The cooling temperature of the condenser (18) is 45°C.

5. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The compressor (22) increases the regeneration gas pressure to 0.05-0.1 MPa greater than the inlet pressure.

6. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The exhaust port of the second separator (20) is connected to the inlet of the dehydration tower (6).

7. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The system also includes a first inlet and outlet tower valve group and a second inlet and outlet tower valve group, and the inlet and outlet gases of the dehydration tower (6) and the regeneration tower (7) are connected to external equipment through the first inlet and outlet tower valve group and the second inlet and outlet tower valve group.

8. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The dehydration tower (6), the regeneration tower (7), the first separator (5) and the second separator (20) are all connected to a sewage pipe.

9. A carbon dioxide combined dehydration system as claimed in claim 1, characterized in that: The dehydration tower (6) and the regeneration tower (7) are operated in an alternating dehydration and regeneration process, and the opening and closing states of the control valves with the same function arranged on the dehydration tower (6) and the regeneration tower (7) are opposite.

10. The carbon dioxide combined dehydration system according to claim 1, characterized in that: A first venting pipeline (3) is also connected between the filter separator (2) and the cold dryer (4), and a second venting pipeline (16) is connected to both the dehydration tower (6) and the regeneration tower (7).

Images