Temperature control method and natural gas molecular sieve dehydration system

Abstract

This application discloses a temperature control method and a natural gas molecular sieve dehydration system, relating to the field of natural gas extraction. The temperature control method, applied to a natural gas molecular sieve dehydration system, includes: detecting the temperature at a first interface and a second interface of a heating element, wherein one of the first interface and the second interface is an inlet and the other is an outlet; comparing the temperature values ​​at the inlet and the outlet; during the switching from a hot-blowing sequence to a cold-blowing sequence in the molecular sieve dehydration tower of the natural gas molecular sieve dehydration system, when the temperature value at the inlet is higher than the temperature value at the outlet, controlling the heating element to reduce its power; when the temperature value at the inlet is lower than or equal to the temperature value at the outlet, controlling the heating element to perform PID control. This application can solve problems such as frequent shutdowns due to excessively high internal temperatures of the electric heater.

Description

Technical Field

[0001] This application belongs to the field of natural gas extraction technology, specifically relating to a temperature control method and a natural gas molecular sieve dehydration system. Background Technology

[0002] With the increasing development of natural gas extraction in remote mountainous areas of China, especially shale gas extraction in the Sichuan-Chongqing region, which is mostly located deep in the mountains, the transportation of extracted natural gas is a pressing issue. Wellheads are not concentrated in these remote areas, making the construction of long-distance pipelines difficult and costly. Instead, small skid-mounted wellhead liquefaction units are used near the wellheads to liquefy the extracted natural gas before transporting it via cryogenic tank trucks. Before liquefaction, the wellhead gas requires purification treatments such as sand removal, acid removal, and dehydration.

[0003] In natural gas dehydration processes using molecular sieves, when the processing scale is large, heat transfer oil is generally used to heat the regenerated gas. However, in some small molecular sieve dehydration units, electric heaters are often used to heat the regenerated gas. Molecular sieve dehydration processes are further divided into 2-tower, 2+1 (2.5-tower), 3-tower, and 4-tower processes. In the 2+1 (2.5-tower) process, the regenerated gas flows through the electric heater in different directions at different time stages. When the adsorption tower, which has already undergone hot blowing, switches to the cold blowing process (time sequence switching), the regenerated gas flowing through the electric heater needs to change direction (from forward to reverse or vice versa). At this time, because the temperature of the adsorption tower after hot blowing is very high, the temperature of the regenerated gas flowing to the electric heater will also be high. Simultaneously, due to the low heat capacity of the gas, it cannot quickly remove the heat generated by the electric heater, causing the electric heater to frequently shut down due to internal overheating. Summary of the Invention

[0004] The purpose of this application is to provide a temperature control method and a natural gas molecular sieve dehydration system, which can solve problems such as frequent shutdowns due to excessively high internal temperatures of the electric heater.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] This application provides a temperature control method applied to a natural gas molecular sieve dehydration system, the temperature control method comprising:

[0007] The temperature at each of the first and second interfaces of the heating element is detected, wherein one of the first and second interfaces is the inlet and the other is the outlet;

[0008] The temperature values ​​at the inlet and the outlet are compared.

[0009] During the process of switching from hot blowing sequence to cold blowing sequence in the molecular sieve dehydration tower of the natural gas molecular sieve dehydration system, when the temperature value at the inlet is higher than the temperature value at the outlet, the heating element is controlled to reduce its power.

[0010] When the temperature at the inlet is lower than or equal to the temperature at the outlet, the heating element is controlled by PID control.

[0011] This application also provides a natural gas molecular sieve dehydration system, including: a molecular sieve dehydration tower, a control element, a heating element, a cooling element, a first temperature detection element, and a second temperature detection element;

[0012] The molecular sieve dehydration tower has a first opening and a second opening. The heating element is connected to the first opening through a hot air blowing pipeline, and the cooling element is connected to the second opening through a cold air blowing pipeline.

[0013] The heating element has a first interface and a second interface, the first temperature detection element is disposed at the first interface, and the second temperature detection element is disposed at the second interface;

[0014] The control element is electrically connected to the heating element, the cooling element, the first temperature detection element, and the second temperature detection element, respectively. The control element is used to control the heating element to reduce its power when the temperature value at the inlet is higher than the temperature value at the outlet during the process of switching the molecular sieve dehydration tower from hot blowing sequence to cold blowing sequence, and to control the heating element to perform PID control when the temperature value at the inlet is lower than or equal to the temperature value at the outlet.

[0015] In this embodiment, the temperature at the first interface of the heating element is monitored in real time, as is the temperature at the second interface. The detected temperature values ​​at the first and second interfaces are compared. Furthermore, one of the first and second interfaces can serve as an inlet, and the other as an outlet. Thus, during the transition from hot blowing to cold blowing in the molecular sieve dehydration tower of the natural gas molecular sieve dehydration system, when the inlet temperature is higher than the outlet temperature, the heating element is controlled to reduce its heating power. When the inlet temperature is lower than or equal to the outlet temperature, the heating element is controlled using PID control to ensure that the outlet temperature fluctuates within a preset range. Through this control method, this embodiment effectively prevents the heating element from overheating and shutting down during the molecular sieve dehydration sequence switching, thereby ensuring stable operation of the heating element. Attached Figure Description

[0016] Figure 1 This is a flowchart of the temperature control method disclosed in the embodiments of this application;

[0017] Figure 2 This is a schematic diagram of the control logic of the temperature control method disclosed in the embodiments of this application;

[0018] Figure 3 This is a schematic diagram of the control principle of the temperature control method disclosed in the embodiments of this application;

[0019] Figure 4 This is a schematic diagram of the natural gas molecular sieve dehydration system disclosed in the embodiments of this application;

[0020] Figure 5 This is a schematic diagram showing the connections of various components in the natural gas molecular sieve dehydration system disclosed in the embodiments of this application;

[0021] Figure 6 This is a schematic diagram of the structure of the heating element disclosed in the embodiments of this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] 10-Control element; 11-Main controller; 12-Secondary controller; 20-Heating element; 21-First interface; 22-Second interface; 23-Heating tube; 30-Refrigeration element; 41-First temperature detection element; 42-Second temperature detection element; 43-Third temperature detection element; 44-Flow detection element; 51-Main control circuit; 52-Main feedback branch; 53-Secondary feedback branch; 60-Regulator; 70-Molecular sieve dehydration tower. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, the specification and...

[0026] In the claims, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0027] The embodiments of this application will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.

[0028] refer to Figures 1 to 6 This application discloses a temperature control method applied to natural gas.

[0029] A molecular sieve dehydration system is provided to facilitate temperature control of natural gas. The disclosed temperature control method includes:

[0030] The temperatures at the first interface 21 and the second interface 22 of the heating element 20 are measured respectively.

[0031] One of the first interface 21 and the second interface 22 is the import port, and the other is the export port;

[0032] Compare the temperature values ​​at the inlet and outlet;

[0033] During the process of switching from hot blowing sequence to cold blowing sequence 5 in the molecular sieve dehydration tower 70 of the natural gas molecular sieve dehydration system:

[0034] When the temperature at the inlet is higher than the temperature at the outlet, the heating element 20 is controlled to reduce its power.

[0035] When the temperature at the inlet is lower than or equal to the temperature at the outlet, the heating element 20 is controlled by PID.

[0036] Specifically, during the operation of the natural gas molecular sieve dehydration system, the molecular sieve dehydration tower 70 can include adsorption sequence, hot blowing sequence, and cold blowing sequence. Through the periodic operation of the above sequence, the dehydration of natural gas can be achieved.

[0037] Natural gas undergoes dehydration treatment to prevent freezing and blockage of related equipment during subsequent processing and to prevent the precipitation of liquid water during storage and transportation, thus ensuring the normal operation of production.

[0038] In the natural gas dehydration process using molecular sieves, heating element 20 is used to feed the regenerated gas.

[0039] Heating is performed. However, the regeneration gas flows through the heating element 20 in both directions at different time stages. For example, in the hot blowing stage, the regeneration gas can flow in from the first port 21 of the heating element 20 and from the second port 21...

[0040] The second port 22 flows out; during the cold blowing phase, the regenerated gas can flow in from the second port 22 of the heating element 20 and flow out from the first port 21; of course, it can also flow in the opposite direction.

[0041] When the molecular sieve dehydration tower 70, which has completed the hot blowing phase, switches to the cold blowing phase, the regeneration gas flowing through the heating element 20 needs to change its flow direction, causing the gas in the molecular sieve dehydration tower 70 to flow towards the heating element 20. At this time, because the temperature of the molecular sieve dehydration tower 70 after hot blowing is very high, the temperature of the regeneration gas flowing towards the heating element 20 is also high. At the same time, because the heat capacity of the regeneration gas is low, it cannot remove the heat generated by the heating element 20 in a short time. As a result, the high temperature of the regeneration gas entering the heating element 20 will cause the temperature inside the heating element 20 to be too high, which will cause the heating element 20 to frequently shut down due to internal overheating, thus affecting the normal operation of the entire natural gas molecular sieve dehydration system.

[0042] Therefore, by detecting and comparing the temperature at the first interface 21 and the temperature at the second interface 22, this embodiment of the application enables adaptive control based on the temperature difference between the two interfaces during the process of switching the molecular sieve dehydration tower 70 from hot blowing sequence to cold blowing sequence. This ensures that the high-temperature gas in the molecular sieve dehydration tower 70 after hot blowing does not cause the internal temperature of the heating element 20 to become too high after entering the heating element 20, thereby guaranteeing the normal use of the heating element 20 and the normal operation of the entire natural gas molecular sieve dehydration system.

[0043] Specifically, when the detected temperature at the inlet of the heating element 20 is higher than the temperature at the outlet, it indicates that the temperature of the regeneration gas returning to the heating element 20 is too high. In this case, the heating element 20 will overheat and shut down. At this time, the heating element 20 can be controlled to reduce its heating power, thereby reducing the heat generated by the heating element 20 itself and lowering its internal temperature. In this way, even if the temperature of the regeneration gas returning to the heating element 20 is high, it will not cause the internal temperature of the heating element 20 to exceed the set value, thus preventing the heating element 20 from overheating and shutting down. This ensures the stable operation of the heating element 20 and further enables the normal operation of the natural gas molecular sieve dehydration system.

[0044] When the detected temperature value at the inlet of the heating element 20 is lower than or equal to the temperature value at the outlet, it indicates that the temperature of the regeneration gas flowing back to the heating element 20 is not too high. In this case, even if the regeneration gas enters the interior of the heating element 20, it will not cause the heating element 20 to overheat and shut down. Thus, the heating element 20 is controlled normally by PID control to achieve reasonable control of the regeneration gas temperature.

[0045] Optionally, the temperature control method further includes:

[0046] Detect the temperature value inside the heating element 20;

[0047] When the temperature at the inlet is higher than the temperature at the outlet, and the temperature inside the heating element 20 is higher than the first preset temperature, the heating element 20 is controlled to reduce its power.

[0048] When the internal temperature of the heating element 20 is lower than or equal to the first preset temperature value, the heating element 20 is controlled by PID control.

[0049] It should be noted that because the temperature of different parts of the heating element 20 is different, the temperature values ​​at the first interface 21 and the second interface 22 may deviate from the temperature value inside the heating element 20. This may result in the temperature values ​​at the first interface 21 and the second interface 22 meeting the requirements, but the temperature inside the heating element 20 being too high. In this case, the heating element 20 will also stop.

[0050] Based on the above, the embodiments of this application can detect the internal temperature value of the heating element 20, so that it can be used together with the temperature values ​​at the first interface 21 and the second interface 22 to characterize the temperature of the heating element 20. Therefore, when the temperature values ​​at the first interface 21, the second interface 22 and the internal temperature value of the heating element 20 all meet the requirements, it indicates that the heating element 20 is in normal working condition and there is no internal overheating, thereby ensuring the stable operation of the heating element 20.

[0051] However, when the internal temperature of the heating element 20 is higher than the first preset temperature value, it indicates that the internal temperature of the heating element 20 is too high, which may easily lead to shutdown. Therefore, the heating power of the heating element 20 can be appropriately reduced to prevent the internal temperature of the heating element 20 from being too high and causing shutdown.

[0052] For example, a temperature detection element can be provided on the heating tube 23 inside the heating element 20 to more accurately detect the temperature value inside the heating element 20, thereby reducing the probability of the heating element 20 shutting down.

[0053] Furthermore, the temperature control method may also include:

[0054] The temperature values ​​at multiple points inside the heating element 20 are detected, and these multiple points are spaced apart along the flow direction of the natural gas inside the heating element 20.

[0055] When the temperature value at at least one of the multiple locations is higher than the first preset temperature value, the heating element 20 is controlled to reduce the power.

[0056] When the temperature values ​​at multiple locations are all lower than or equal to the first preset temperature value, the heating element 20 is controlled by PID control.

[0057] By measuring the temperature at multiple points inside the heating element 20, the temperature at multiple locations inside the heating element 20 can be obtained more comprehensively, thereby improving the accuracy of temperature detection inside the heating element 20 and avoiding situations where local high temperatures occur inside the heating element 20, which could affect the stable operation of the heating element 20.

[0058] Based on the above settings, when the temperature value at at least one location is higher than the first preset temperature value, it is determined that the internal temperature of the heating element 20 is too high. In this case, the internal temperature can be reduced by decreasing the power of the heating element 20 to avoid overheating. Conversely, when the temperature values ​​at all detection locations are lower than or equal to the first preset temperature value, it is determined that the internal temperature of the heating element 20 is not overheating. In this case, the heating element 20 can operate in a stable state.

[0059] For example, multiple locations of the heating tube 23 inside the heating element 20 can be selected as detection points, and the multiple detection points can be distributed as much as possible at various locations of the heating tube 23 in order to improve the temperature detection accuracy.

[0060] Considering that during the hot blowing phase, when the flow rate of regeneration gas into the heating element 20 is small or interrupted, the amount of heat carried away by the regeneration gas inside the heating element 20 is reduced, causing the temperature inside the heating element 20 to rise. After a long period of heat accumulation, the heating element 20 becomes overheated, affecting the stable operation of the heating element 20.

[0061] Based on the above, the temperature control method in this application embodiment further includes:

[0062] When the flow rate in the natural gas pipeline is less than the preset flow rate, the heating element 20 is controlled to reduce its power or stop. In this way, when the flow rate of regenerated gas from the natural gas pipeline to the heating element 20 is relatively small, the heating element 20 can be controlled to reduce its power, thereby reducing the heat generated inside the heating element 20 and controlling the internal temperature of the heating element 20 to a certain extent so as not to be too high. When the natural gas pipeline is cut off and regenerated gas cannot enter the heating element 20, the heating element 20 is controlled to stop. At this time, the heating element 20 no longer generates heat, thereby preventing the internal temperature of the heating element 20 from overheating.

[0063] Considering the working cycle of the hot blowing sequence, in order to ensure that the temperature inside the molecular sieve dehydration tower 70 meets the temperature requirements during the hot blowing phase, in this embodiment of the application, the temperature control method during the hot blowing process in the molecular sieve dehydration tower 70 may further include:

[0064] The temperature value inside the outlet pipeline of molecular sieve dehydration tower 70 was detected;

[0065] When a hot blowing cycle is reached, if the temperature value in the air outlet pipeline is lower than the second preset temperature value, the control delays for one cycle and continues to execute the hot blowing sequence.

[0066] Specifically, during the hot blowing process, the heating switching timer starts counting. When one heating cycle is reached, the temperature value at the outlet pipe of the molecular sieve dehydration tower 70 is checked to see if it has reached the second preset temperature value. If it has reached the second preset temperature value, the molecular sieve dehydration tower 70 is determined to have completed the regeneration heating process. At this time, the switch can be made to enter the cold blowing sequence stage. If the second preset temperature value has not been reached, heating continues and the delay timer counts for one cycle to perform hot blowing. After the delay cycle is completed, the temperature value at the outlet pipe is checked again until the temperature at the outlet pipe reaches the second preset temperature value, and then the switch is made to the cold blowing sequence stage.

[0067] Based on the above temperature control method, this application also discloses a natural gas molecular sieve dehydration system, such as... Figures 1 to 6 As shown, the disclosed natural gas molecular sieve dehydration system includes: a molecular sieve dehydration tower 70, a control element 10, a heating element 20, a cooling element 30, a first temperature detection element 41, and a second temperature detection element 42.

[0068] The molecular sieve dehydration tower 70 has a first opening and a second opening. The heating element 20 is connected to the first opening through a hot blowing pipeline, and the cooling element 30 is connected to the second opening through a cold blowing pipeline. In this way, heated gas can be introduced into the molecular sieve dehydration tower 70 through the first opening via the hot blowing pipeline to realize the hot blowing process. Similarly, cooled gas can be introduced into the molecular sieve dehydration tower 70 through the second opening via the cooling pipeline to realize the cold blowing process.

[0069] The heating element 20 has a first interface 21 and a second interface 22. A first temperature sensing element 41 is disposed at the first interface 21, and a second temperature sensing element 42 is disposed at the second interface 22. One of the first interface 21 and the second interface 22 is an inlet, and the other is an outlet. As the gas direction changes at different time stages, the first interface 21 and the second interface 22 can switch between inlet and outlet. The first temperature sensing element 41 detects the temperature value at the first interface 21 in real time, and the second temperature sensing element 42 detects the temperature value at the second interface 22 in real time.

[0070] The control element 10 is electrically connected to the heating element 20, the cooling element 30, the first temperature detection element 41, and the second temperature detection element 42, respectively, so that the temperature information detected by the first temperature detection element 41 and the second temperature detection element 42 are sent to the control element 10 for comparison, analysis, and processing. In addition, the control element 10 can also control the heating element 20 to perform a hot blowing sequence process, and control the cooling element 30 to perform a cold blowing sequence process.

[0071] During the process of switching from hot blowing to cold blowing in the molecular sieve dehydration tower 70, if the temperature at the inlet is higher than the temperature at the outlet, it indicates that the temperature of the regeneration gas returning to the heating element 20 is too high. In this case, the heating element 20 will overheat and shut down. At this time, the control element 10 controls the heating element 20 to reduce the heating power, thereby reducing the heat emitted by the heating element 20 itself and lowering its internal temperature. Thus, even if the temperature of the regeneration gas returning to the heating element 20 is high, it will not cause the internal temperature of the heating element 20 to exceed the set value, and the heating element 20 will not overheat and shut down. This ensures the stable operation of the heating element 20 and further realizes the normal operation of the natural gas molecular sieve dehydration system.

[0072] When the temperature at the inlet is lower than or equal to the temperature at the outlet, it indicates that the temperature of the regenerated gas returning to the heating element 20 is not too high. In this case, even if the regenerated gas enters the heating element 20, it will not cause the heating element 20 to overheat and shut down. At this time, the control element 10 is used to control the heating element 20 to perform PID control in order to achieve reasonable control of the regenerated gas temperature.

[0073] In some embodiments, the natural gas molecular sieve dehydration system may further include a third temperature sensing element 43, which is electrically connected to the control element 10 to send a temperature signal to the control element 10. The heating element 20 has a heating tube 23 inside, and the third temperature sensing element 43 is disposed on the heating tube 23.

[0074] Based on the above settings, the temperature of the heating tube 23 inside the heating element 20 can be detected in real time by the third temperature detection element 43. When the temperature value at the inlet is higher than the temperature value at the outlet, and the temperature value inside the heating element 20 is higher than the first preset temperature value, it indicates that the internal temperature of the heating element 20 is too high, which may easily lead to shutdown. Therefore, the heating element 20 can be appropriately reduced by the control element 10 to prevent the internal temperature of the heating element 20 from being too high and causing shutdown.

[0075] When the temperature value inside the heating element 20 detected by the third temperature detection element 43 is lower than or equal to the first preset temperature value, it indicates that the heating element 20 is in normal working condition and there is no internal overheating. At this time, the heating element 20 is controlled by PID to ensure the stable operation of the heating element 20.

[0076] Furthermore, the natural gas molecular sieve dehydration system may include multiple third temperature sensing elements 43, which are spaced apart along the flow direction of natural gas inside the heating element 20. This allows for more comprehensive temperature measurement at multiple locations inside the heating element 20, thereby improving the accuracy of temperature detection inside the heating element 20 and preventing localized high temperatures from affecting the stable operation of the heating element 20.

[0077] Based on the above settings, when at least one temperature value detected by multiple third temperature sensing elements 43 is higher than the first preset temperature value, the control element 10 determines that the internal temperature of the heating element 20 is too high. At this time, the internal temperature can be reduced by decreasing the power of the heating element 20 to avoid overheating. Conversely, when the temperature values ​​detected by all third temperature sensing elements 43 are lower than or equal to the first preset temperature value, the control element 10 determines that the internal temperature of the heating element 20 is not overheating, and the heating element 20 can operate in a stable state.

[0078] For example, multiple locations of the heating tube 23 inside the heating element 20 can be selected as detection points, and multiple third temperature detection elements 43 can be distributed as much as possible at various locations of the heating tube 23 in order to improve the temperature detection accuracy.

[0079] In some embodiments, the natural gas molecular sieve dehydration system may further include a regulator 60 for adjusting the heating power of the heating element 20. For example, the regulator 60 may be a thyristor regulator or the like. Additionally, the control element 10 may include a main controller 11 and a secondary controller 12, wherein the main controller 11, the secondary controller 12, the regulator 60, the third temperature sensing element 43, and the first temperature sensing element 41 or the second temperature sensing element 42 are connected in series to form a main control circuit 51; and the first temperature sensing element 41 or the second temperature sensing element 42 is connected to the main controller 11 through a main feedback branch 52, and the third temperature sensing element 43 is connected to the secondary controller 12 through a secondary feedback branch 53.

[0080] Based on the above settings, a cascade regulation control loop can be formed by the first temperature detection element 41 set at the first interface 21, the second temperature detection element 42 set at the second interface 22, and the third temperature detection element 43 set inside the heating element 20, so as to realize the timely and stable operation of the heating element 20.

[0081] Specifically, when the temperature of the regeneration gas detected by the first temperature detection element 41 or the second temperature detection element 42 is too high or too low, a signal is sent to the main controller 11 through the main feedback branch 52 to control the heating element 20 to make adaptive adjustments; when the temperature inside the heating element 20 detected by the third temperature detection element 43 is too high or too low, a signal is sent to the secondary controller 12 through the secondary feedback branch 53, which can also control the heating element 20 to make adaptive adjustments.

[0082] Considering that during the hot blowing phase, when the flow rate of regeneration gas into the heating element 20 is small or interrupted, the amount of heat carried away by the regeneration gas inside the heating element 20 is reduced, causing the temperature inside the heating element 20 to rise. After a long period of heat accumulation, the heating element 20 becomes overheated, affecting the stable operation of the heating element 20.

[0083] Based on the above, the natural gas molecular sieve dehydration system in this application embodiment may further include a flow detection element 44, which is disposed in the natural gas transmission pipeline and electrically connected to the control element 10. The control element 10 is used to control the heating element 20 to reduce power or stop when the flow detection element 44 detects that the gas flow rate in the natural gas transmission pipeline is less than the preset flow rate.

[0084] Specifically, when the regenerated gas flow rate from the natural gas pipeline to the heating element 20 detected by the flow detection element 44 is relatively small, the heating element 20 can be controlled to reduce its power in order to reduce the heat generated inside the heating element 20 and, to a certain extent, control the temperature inside the heating element 20 to prevent it from becoming too high. When the flow rate in the natural gas pipeline detected by the flow detection element 44 is zero, indicating that the natural gas pipeline has been cut off and the regenerated gas cannot enter the heating element 20, the control element 10 controls the heating element 20 to stop. At this time, the heating element 20 no longer generates heat, thereby preventing the heating element 20 from overheating.

[0085] In summary, this application embodiment, without increasing costs, can stably control the heating temperature of the heating element 20 by designing the control program, thereby ensuring the stability of the regeneration gas temperature of the molecular sieve dehydration tower 70 during and after the timing switching process; furthermore, under the dual protection of internal over-temperature protection and low regeneration gas flow restriction, the safety and stability of the heating element 20 operation can be effectively improved.

[0086] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A temperature control method applied to a natural gas molecular sieve dehydration system, characterized in that, The temperature control method includes: The temperature at each of the first interface (21) and the second interface (22) of the heating element (20) is detected respectively, wherein one of the first interface (21) and the second interface (22) is the inlet and the other is the outlet; The temperature values ​​at the inlet and the outlet are compared. During the process of switching from hot blowing sequence to cold blowing sequence in the molecular sieve dehydration tower (70) of the natural gas molecular sieve dehydration system: When the temperature at the inlet is higher than the temperature at the outlet, the heating element (20) is controlled to reduce its power. When the temperature at the inlet is lower than or equal to the temperature at the outlet, the heating element (20) is controlled by PID control.

2. The temperature control method according to claim 1, characterized in that, The temperature control method further includes: Detect the temperature value inside the heating element (20); When the temperature value at the inlet is higher than the temperature value at the outlet, when the temperature value inside the heating element (20) is higher than the first preset temperature value, the heating element (20) is controlled to reduce its power. When the temperature value inside the heating element (20) is lower than or equal to the first preset temperature value, the heating element (20) is controlled to perform PID control.

3. The temperature control method according to claim 2, characterized in that, The temperature control method includes: The temperature values ​​at multiple points inside the heating element (20) are detected, and the multiple points are spaced apart along the flow direction of the natural gas inside the heating element (20); When the temperature value at at least one of the multiple locations is higher than the first preset temperature value, the heating element (20) is controlled to reduce its power; When the temperature values ​​at multiple locations are all lower than or equal to the first preset temperature value, the heating element (20) is controlled to perform PID control.

4. The temperature control method according to claim 1, characterized in that, The temperature control method includes: When the flow rate in the natural gas pipeline is less than the preset flow rate, the heating element (20) is controlled to reduce its power or stop.

5. The temperature control method according to claim 1, characterized in that, During the hot blowing process in the molecular sieve dehydration tower (70), the temperature control method includes: The temperature value inside the outlet pipeline of the molecular sieve dehydration tower (70) is detected; When a hot blowing cycle is reached, if the temperature value in the air outlet pipeline is lower than the second preset temperature value, the hot blowing sequence is continued for a delay of one cycle.

6. A natural gas molecular sieve dehydration system, characterized in that, include: Molecular sieve dehydration tower (70), control element (10), heating element (20), refrigeration element (30), first temperature detection element (41), and second temperature detection element (42); The molecular sieve dehydration tower (70) has a first opening and a second opening. The heating element (20) is connected to the first opening through a hot air blowing pipeline, and the cooling element (30) is connected to the second opening through a cold air blowing pipeline. The heating element (20) has a first interface (21) and a second interface (22). The first temperature detection element (41) is disposed at the first interface (21), and the second temperature detection element (42) is disposed at the second interface (22). One of the first interface (21) and the second interface (22) is an inlet, and the other is an outlet. The control element (10) is electrically connected to the heating element (20), the cooling element (30), the first temperature detection element (41), and the second temperature detection element (42), respectively. The control element (10) is used to control the heating element (20) to reduce its power when the temperature value at the inlet is higher than the temperature value at the outlet during the process of switching the molecular sieve dehydration tower (70) from hot blowing sequence to cold blowing sequence, and to control the heating element (20) to perform PID control when the temperature value at the inlet is lower than or equal to the temperature value at the outlet.

7. The natural gas molecular sieve dehydration system according to claim 6, characterized in that, The natural gas molecular sieve dehydration system also includes a third temperature detection element (43), which is electrically connected to the control element (10); The heating element (20) has a heating tube (23) inside, and the third temperature detection element (43) is disposed on the heating tube (23). The control element (10) is used to control the heating element (20) to reduce power when the temperature value inside the heating element (20) is higher than the first preset temperature value when the temperature value inside the heating element (20) is higher than the first preset temperature value, and to control the heating element (20) to perform PID control when the temperature value inside the heating element (20) is lower than or equal to the first preset temperature value.

8. The natural gas molecular sieve dehydration system according to claim 7, characterized in that, The natural gas molecular sieve dehydration system includes a plurality of the third temperature detection elements (43), which are spaced apart along the flow direction of the natural gas inside the heating element (20). The control element (10) is used to control the heating element (20) to reduce power when the temperature value detected by at least one of the plurality of third temperature detection elements (43) is higher than the first preset temperature value, and to control the heating element (20) to perform PID control when the temperature values ​​detected by the plurality of third temperature detection elements (43) are all lower than or equal to the first preset temperature value.

9. The natural gas molecular sieve dehydration system according to claim 8, characterized in that, The natural gas molecular sieve dehydration system also includes a regulator (60). The control element (10) includes a main controller (11) and a secondary controller (12). The main controller (11), the secondary controller (12), the regulator (60), the third temperature detection element (43), and the first temperature detection element (41) or the second temperature detection element (42) are connected in series to form a control main circuit (51). The first temperature sensing element (41) or the second temperature sensing element (42) is connected to the main controller (11) through the main feedback branch (52), and the third temperature sensing element (43) is connected to the sub-controller (12) through the sub-feedback branch (53).

10. The natural gas molecular sieve dehydration system according to claim 7, characterized in that, The natural gas molecular sieve dehydration system also includes a flow detection element (44), which is installed in the natural gas transmission pipeline and electrically connected to the control element (10); The control element (10) is used to control the heating element (20) to reduce power or stop when the flow value detected by the flow detection element (44) is less than the preset flow value.

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