Biogas dehydration method and system

Abstract

The invention relates to the technical field of biogas treatment, in particular to a biogas dehydration system which comprises a dehydration tank, a gas inlet, a dehydrator, a flow guide pipe, a liquid level meter connector and a water drainage port, biogas enters the dehydration tank from the gas inlet and moves downwards in the flow guide pipe, mechanical water carried by the biogas is separated out through inertia force and deposited to the bottom of the dehydration tank, and the dehydration tank is used for dehydration. Gas flowing upwards is discharged through the dehydrator, the water level of the dehydration tank is monitored in real time through an instrument connected with the liquid level meter interface, the water outlet is used for discharging mechanical water deposited at the bottom of the dehydration tank, the water outlet is connected with an electromagnetic valve, and the electromagnetic valve is automatically controlled by the liquid level controller to be opened and closed to discharge water. By integrating mechanical separation, interval liquid level control, feed-forward compensation type dynamic threshold adjustment and intelligent diagnosis of the drainage process, efficient separation, self-adaptive control, safe drainage and intelligent operation of the biogas dehydration system are realized.

Description

Technical Field

[0001] This invention relates to the field of biogas treatment technology, and in particular to a biogas dehydration method and system. Background Technology

[0002] Biogas, as a clean and renewable energy source, is widely used in power generation, heating, boiler combustion, and the purification and production of biomethane. In practical engineering applications, moisture control is one of the key aspects of the stable operation of biogas utilization systems. Untreated biogas is typically saturated with water vapor and contains liquid water droplets (i.e., "mechanical water"). If this moisture is not effectively removed, it will cause serious damage to downstream equipment, including corrosion of pipes and equipment, blockage of pipelines, and interference with measuring instruments. Therefore, effective dehydration treatment is essential before biogas enters end-use energy equipment (such as boilers and generators).

[0003] Currently, common biogas dehydration methods mainly fall into three categories: cooling and condensation, adsorption and drying, and mechanical separation. However, existing mechanical dehydration systems still have the following significant shortcomings: 1) Mechanical water separation is inefficient, residual water affects combustion stability, liquid level monitoring relies on manual labor, and drainage is untimely or excessive; 2) The liquid level control method is simple, but the use of single-point liquid level control leads to frequent opening and closing of the drain solenoid valve, easy damage to the equipment, and unstable system operation. 3) Lack of feedforward control mechanism and delayed response: Traditional systems rely solely on liquid level feedback signals for control, which is a "post-event response" mode. Traditional biogas dehydration systems use fixed liquid level threshold control, which cannot adapt to fluctuations in biogas flow and moisture content. This leads to problems such as delayed drainage (risk of water contamination) under high load and frequent drainage (equipment wear) under low load, resulting in significant time delays and difficulty in adapting to dynamically changing operating conditions. 4) Lack of fault diagnosis and safety redundancy design: Traditional biogas dehydration systems only achieve "automatic start-stop drainage", lacking effective monitoring of the drainage process. They cannot detect problems such as solenoid valve failure, poor drainage or pipe blockage in a timely manner, which poses safety hazards such as uncontrolled liquid level and water in biogas. In summary, while existing biogas dehydration systems can achieve basic mechanical water separation, they still have significant shortcomings in terms of intelligent control, dynamic adaptability, operational safety, and maintainability. Especially in small and medium-sized biogas projects, there is an urgent need for a dehydration system that is structurally sound, intelligently controlled, safe, reliable, and easy to operate and maintain, in order to improve overall operational efficiency and stability. Summary of the Invention

[0004] This invention provides a biogas dehydration method and system, which integrates mechanical separation, interval liquid level control, feedforward compensation dynamic threshold adjustment and intelligent diagnosis of drainage process to achieve efficient separation, adaptive control, safe drainage and intelligent operation of biogas dehydration system.

[0005] To achieve the objective of this invention, the technical solution adopted is as follows: a biogas dehydration system, comprising: a dehydration tank, a gas inlet, a water separator, a guide pipe, a level gauge interface, and a drain outlet. Biogas enters the dehydration tank through the gas inlet and moves downward within the guide pipe. The mechanical water entrained in the biogas is separated by inertial force and deposited at the bottom of the dehydration tank. The upward-flowing gas is discharged through the water separator. The water level in the dehydration tank is monitored in real time by an instrument connected to the level gauge interface. The drain outlet is used to discharge the mechanical water deposited at the bottom of the dehydration tank. The drain outlet is connected to a solenoid valve, which is automatically controlled by the level controller to open and close for drainage.

[0006] As an optimized solution of the present invention, the liquid level gauge interface includes a high liquid level gauge interface and a low liquid level gauge interface, and the liquid level in the dehydration tank can be controlled in a range through the high liquid level gauge interface and the low liquid level gauge interface.

[0007] As an optimized solution of the present invention, a liquid level measuring instrument is connected to a liquid level gauge interface set on the side wall of the dehydration tank to monitor the liquid level height in real time; when the liquid level measuring instrument detects that the liquid level has reached the high liquid level set value, it outputs a high switching signal to trigger the solenoid valve at the drain outlet to open; when the liquid level drops to the low liquid level set value, the liquid level measuring instrument outputs a low switching signal to control the solenoid valve at the drain outlet to close.

[0008] As an optimized solution of the present invention, the liquid level measuring instrument is a magnetic float liquid level gauge.

[0009] To achieve the objective of this invention, the technical solution adopted is: a method for biogas dehydration using a biogas dehydration system, comprising: S1. Biogas from the booster fan is introduced into the guide pipe inside the dehydration tank through the gas inlet, so that the biogas flows axially downward in the guide pipe. The inertial force generated by the sudden change in airflow direction causes the mechanical water entrained in the biogas to hit the wall of the guide pipe and break away from the airflow, settling at the bottom of the dehydration tank. S2. After initial dehydration, the biogas moves upward from the bottom of the guide pipe and undergoes secondary dehydration through a water separator located above the guide pipe. After removing residual water mist, it is discharged to the boiler burner for combustion. S3. The liquid level in the dehydration tank is monitored in real time by a liquid level measuring instrument connected to the liquid level gauge interface. When the liquid level reaches the high liquid level set value, the liquid level measuring instrument outputs a control signal to start the solenoid valve at the drain outlet for automatic drainage. When the liquid level drops to the low liquid level set value, the solenoid valve is closed, completing one automatic drainage cycle.

[0010] As an optimized solution of the present invention, the liquid level measuring instrument detects the high liquid level signal and the low liquid level signal through the high liquid level gauge interface and the low liquid level gauge interface respectively, so as to realize the interval closed-loop control of the liquid level in the dehydration tank.

[0011] As an optimized solution of the present invention, the dynamic setting method for the liquid level threshold based on feedforward compensation is determined according to the biogas flow rate Q. g The method for dynamically setting the high / low liquid level setpoint based on feedforward compensation, which dynamically adjusts the high / low liquid level setpoint along with the water content w, is as follows: H high =H0+k×T× H low = H high -ΔH Wherein: H high H is the high liquid level setpoint. low H0 is the low liquid level setpoint, k is the reference high liquid level, A is the cross-sectional area of ​​the dehydration tank, ΔH is the fixed liquid level difference, and T is the reference time interval.

[0012] As an optimized solution of the present invention, while performing dynamic adjustment of the liquid level threshold, the system continuously monitors the drainage cycle duration T. drain and liquid level drop rate When T is detected drain < and < <R low When T is detected, it is determined that the drain outlet is not draining properly or the solenoid valve is not fully open, and the system switches to manual drain mode; drain >T max At that time, it was determined that there was silt accumulation at the bottom of the tank or blockage in the drain pipe; among them, T drain The duration of a single drainage cycle. R is the rate of drop in liquid level during the drainage process. low T is the threshold for the rate of drop in liquid level. max This is the longest permissible drainage time.

[0013] The present invention has the following positive effects: 1) The present invention solves the problems of low mechanical water separation efficiency, residual water affecting combustion stability, reliance on manual liquid level monitoring, untimely or excessive drainage, and low system integration of existing biogas dehydration devices, and provides a biogas dehydration system with reasonable structure, high separation efficiency, safe operation and automatic drainage function. 2) This invention introduces a feedforward compensation mechanism based on biogas flow rate and water content to dynamically adjust the high / low liquid level setpoints, thereby achieving adaptive adjustment of the control strategy and significantly improving the stability, safety and equipment lifespan of the system under varying operating conditions. 3) This invention constructs a health status assessment mechanism for the drainage process by jointly monitoring the drainage cycle duration and the rate of liquid level drop, thereby avoiding the risk of full tank due to actuator failure; reducing the safety hazards of uncontrolled liquid level and biogas carrying water, and guiding regular dredging and maintenance, thus realizing the inherent safety and intelligent operation and maintenance of the dehydration system. Attached Figure Description

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0015] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a structural diagram of the system of the present invention; The components are: 1. Dehydration tank 1, 2. Gas inlet, 3. Water separator, 4. Guide pipe, 5. Level gauge interface, and 6. Drain outlet. Detailed Implementation

[0016] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] For ease of understanding, the specific process of the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 1This invention discloses a biogas dehydration system, comprising: a dehydration tank 1, a gas inlet 2, a water separator 3, a guide pipe 4, a level gauge interface 5, and a drain outlet 6. Biogas enters the dehydration tank 1 through the gas inlet 2 and moves downward within the guide pipe 4. Inertial force separates the entrained mechanical water from the biogas, depositing it at the bottom of the dehydration tank. The upward-flowing gas is discharged through the water separator 3. An instrument connected to the level gauge interface 5 monitors the water level in the dehydration tank 1 in real time. The drain outlet 6 is used to discharge the mechanical water deposited at the bottom of the dehydration tank. The drain outlet 6 is connected to a solenoid valve, which is automatically controlled by the level controller to open and close for drainage. Specifically, the biogas enters the dehydration tank 1 through the gas inlet 2 and moves downward within the guide pipe 4. After reaching the bottom of the guide pipe 4, the gas reverses direction and moves upward. Under the action of inertial force, the entrained mechanical water is separated and falls to the bottom of the dehydration tank. The upward-flowing gas is discharged after passing through the water separator 3, achieving efficient physical separation of mechanical water without the need for chemical agents or complex energy-consuming equipment. It can remove approximately 85%~90% of mechanical water, significantly improving biogas quality. A water separator 3 (such as a wire mesh collector or swirl plate) is installed above the guide pipe to perform secondary water removal on the rising airflow; further intercepting fine droplets to achieve two-stage dehydration (coarse separation + fine separation). This improves overall dehydration efficiency and ensures the safe and stable operation of downstream equipment. A level gauge interface 5 is installed to connect a level measuring instrument to monitor water level changes in real time. Drain outlet 6 is connected to a solenoid valve, which is automatically opened and closed by the liquid level controller. This enables automatic drainage, reduces manual intervention, avoids flooding accidents caused by human negligence, and improves the continuity and safety of system operation.

[0018] The gas inlet, flow guide structure, water removal element, liquid level monitoring interface, and automatic drainage outlet are integrated into the same dehydration tank, forming an integrated, modular design. This facilitates installation and maintenance, and is suitable for rapid deployment in small to medium-sized biogas projects.

[0019] The level gauge interface 5 includes a high level gauge interface and a low level gauge interface, which enable range control of the liquid level in the dehydration tank 1. By setting up the high level gauge interface and the low level gauge interface, a liquid level control range is formed, realizing stable and intelligent management of the drainage process. This solves the technical problems of frequent opening and closing of the drainage solenoid valve, easy equipment damage, and unstable system operation caused by the single-point liquid level control in traditional biogas dehydration systems. By setting up high / low level gauge interfaces to achieve range control, the life of the actuator is effectively extended, and the reliability and energy efficiency of the system operation are improved.

[0020] A liquid level measuring instrument is connected to the liquid level gauge interface 5 located on the side wall of the dehydration tank 1 to monitor the liquid level in real time. When the liquid level measuring instrument detects that the liquid level has reached the high liquid level set value, it outputs a high switching signal to trigger the solenoid valve at the drain outlet 6 to open. When the liquid level drops to the low liquid level set value, the liquid level measuring instrument outputs a low switching signal to control the solenoid valve at the drain outlet 6 to close. The liquid level measuring instrument is a magnetic float liquid level gauge. The liquid level measuring instrument can output switching signals, i.e., high liquid level and low liquid level, which are linked with the solenoid valve installed at the drain outlet 6 to control the water level in the dehydration tank. That is, the solenoid valve is activated when the liquid level is high and closed when the liquid level is low. The dehydration tank is equipped with a magnetic float liquid level gauge, which is a key component in this biogas dehydration system for realizing visual monitoring of the liquid level and automatic drainage control, combining safety and reliability.

[0021] like Figure 1-2 As shown, the present invention also discloses a method for biogas dehydration using a biogas dehydration system, comprising: S1. Biogas from the booster blower is introduced into the guide pipe 4 inside the dehydration tank 1 through the gas inlet 2, so that the biogas flows axially downward in the guide pipe 4. The mechanical water entrained in the biogas is hit by the guide pipe wall and separated from the airflow by the inertial force generated by the sudden change in airflow direction, and settles at the bottom of the dehydration tank 1. S2. After initial dehydration, the biogas flows upward from the bottom of the guide pipe 4 and undergoes secondary dehydration through the water separator 3 located above the guide pipe 4. After removing residual water mist, the gas is discharged to the boiler burner for combustion. The water separator 3 is installed above the guide pipe 4, in the outlet path of the upward gas movement. The treated gas must pass through the water separator 3 before it can be discharged from the exhaust port.

[0022] S3. The liquid level in the dehydration tank 1 is monitored in real time by a liquid level measuring instrument connected to the liquid level gauge interface 5. When the liquid level reaches the high liquid level set value, the liquid level measuring instrument outputs a control signal to start the solenoid valve at the drain outlet 6 for automatic drainage. When the liquid level drops to the low liquid level set value, the solenoid valve is closed, completing one automatic drainage cycle.

[0023] The liquid level measuring instrument detects the high liquid level signal and the low liquid level signal through the high liquid level gauge interface and the low liquid level gauge interface respectively, so as to realize the interval closed-loop control of the liquid level in the dehydration tank 1.

[0024] The dynamic setting method for liquid level threshold based on feedforward compensation is determined according to the biogas flow rate Q. g The method for dynamically setting the high / low liquid level setpoint based on feedforward compensation, which dynamically adjusts the high / low liquid level setpoint along with the water content w, is as follows: H high =H0+k×T× H low = Hhigh -ΔH Wherein: H high H is the high liquid level setpoint. low Here, H0 is the low liquid level setpoint, k is the reference high liquid level, A is the cross-sectional area of ​​the dehydration tank, ΔH is the fixed liquid level difference, and T is the reference time interval. The compensation coefficient k usually needs to be determined experimentally or through system identification. The initial value can be set to 1 based on the material balance relationship, and then adjusted according to the actual control effect. The reference time interval T should be selected appropriately; too short a value will cause frequent fluctuations in the setpoint, while too long a value will result in a slow response. It is recommended to set it to 1 / 5 to 1 / 10 of the system's main time constant. This is achieved by introducing a Q-based... g The feedforward compensation mechanism of w dynamically adjusts the high / low liquid level setpoints to achieve adaptive adjustment of the control strategy, significantly improving the stability, safety and equipment life under varying operating conditions. By introducing a feedforward compensation mechanism based on biogas flow rate and water content, the liquid level control threshold is dynamically adjusted, enabling the system to respond in advance to the water accumulation trend under high load conditions and avoid biogas carryover caused by drainage lag. At the same time, it reduces ineffective drainage actions under low load conditions, extends the service life of solenoid valves, and realizes intelligent and adaptive operation of the dehydration process.

[0025] While performing dynamic liquid level threshold adjustment, the system continuously monitors the drainage cycle duration T. drain and the rate of liquid level drop When T is detected drain < and < <R low When T is detected, it is determined that the drain outlet is not draining properly or the solenoid valve is not fully open, and the system switches to manual drain mode; drain >T max At that time, it was determined that there was silt accumulation at the bottom of the tank or blockage in the drain pipe; among them, T drain The duration of a single drainage cycle. R is the rate of drop in liquid level during the drainage process. low T is the threshold for the rate of drop in liquid level. max The maximum allowable drainage time (e.g., 10 minutes) will be displayed, and a warning of blockage risk will be issued if the time limit is exceeded. The rate of liquid level drop during drainage should normally be relatively fast; a slow drop indicates poor drainage. This can be addressed by introducing the drainage cycle duration T. drain With the rate of liquid level drop The combined criteria enable real-time diagnosis and fault warning of drainage status, and support mode switching and maintenance reminders, significantly improving the system's safety, reliability and maintainability.

[0026] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biogas dehydration system, characterized in that, include: The dehydration tank (1), gas inlet (2), water separator (3), guide pipe (4), level gauge interface (5), and drain outlet (6) are connected. Biogas enters the dehydration tank (1) through the gas inlet (2) and moves downward in the guide pipe (4). The mechanical water carried by the biogas is separated by inertial force and deposited at the bottom of the dehydration tank. The upward-flowing gas is discharged through the water separator (3). The water level of the dehydration tank (1) is monitored in real time by the instrument connected through the level gauge interface (5). The drain outlet (6) is used to discharge the mechanical water deposited at the bottom of the dehydration tank. The drain outlet (6) is connected to a solenoid valve, which is automatically controlled by the level controller to open and close the solenoid valve for drainage.

2. The biogas dehydration system according to claim 1, characterized in that: The level gauge interface (5) includes a high level gauge interface and a low level gauge interface, which are used to control the level of the liquid in the dehydration tank (1) in a range.

3. The biogas dehydration system according to claim 2, characterized in that: The liquid level is connected to the liquid level measuring instrument via the liquid level gauge interface (5) set on the side wall of the dehydration tank (1) to monitor the liquid level height in real time. When the liquid level measuring instrument detects that the liquid level has reached the high liquid level set value, it outputs a high switching signal to trigger the solenoid valve at the drain outlet (6) to open. When the liquid level drops to the low liquid level set value, the liquid level measuring instrument outputs a low switching signal to control the solenoid valve at the drain outlet (6) to close.

4. The biogas dehydration system according to claim 3, characterized in that: The liquid level measuring instrument is a magnetic float level gauge.

5. A method for biogas dehydration using the biogas dehydration system according to claim 1, characterized in that, include: S1. The biogas from the booster blower is introduced into the guide pipe (4) in the dehydration tank (1) through the gas inlet (2), so that the biogas flows downward along the axis in the guide pipe (4). The mechanical water entrained in the biogas is hit by the guide pipe wall and separated from the airflow by the inertial force generated by the sudden change of airflow direction, and settles at the bottom of the dehydration tank (1). S2. After initial dehydration, the biogas moves upward from the bottom of the guide pipe (4) and undergoes secondary dehydration through the water separator (3) located above the guide pipe (4). After removing residual water mist, it is discharged to the boiler burner for combustion. S3. The liquid level in the dehydration tank (1) is monitored in real time by the liquid level measuring instrument connected to the liquid level gauge interface (5). When the liquid level reaches the high liquid level setting value, the liquid level measuring instrument outputs a control signal to start the solenoid valve at the drain outlet (6) to automatically drain the liquid. When the liquid level drops to the low liquid level setting value, the solenoid valve is closed to complete one automatic drainage cycle.

6. The biogas dehydration method according to claim 5, characterized in that: The liquid level measuring instrument detects the high liquid level signal and the low liquid level signal through the high liquid level gauge interface and the low liquid level gauge interface respectively, so as to realize the interval closed-loop control of the liquid level in the dehydration tank (1).

7. A biogas dehydration method according to claim 6, characterized in that: The dynamic setting method for liquid level threshold based on feedforward compensation is determined according to the biogas flow rate Q. g and moisture content w The dynamic adjustment of high / low liquid level setpoints, based on a feedforward compensation-based dynamic liquid level threshold setting method, is as follows: H low = H high -D H in: H high Set to high liquid level. H low Set to low liquid level. H 0 is the baseline high liquid level. k The compensation coefficient is A, where A is the cross-sectional area of ​​the dehydration tank, and Δ is the cross-sectional area of ​​the tank. H To maintain a fixed liquid level difference, T is the reference time interval.

8. A biogas dehydration method according to claim 7, characterized in that: While dynamically adjusting the liquid level threshold, the system continuously monitors the duration of the drainage cycle. T drain and liquid level drop rate When detected T drain < and << R low If the system determines that drainage from the drain outlet is obstructed or the solenoid valve is not fully open, it will switch to manual drainage mode. T drain > T max At that time, it was determined that there was silt accumulation at the bottom of the tank or a blockage in the drain pipe; among them, T drain The duration of a single drainage cycle. This represents the rate of liquid level drop during the drainage process. R low The threshold for the rate of liquid level drop. T max This is the longest permissible drainage time.

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