Self-propelled CNG recycling multifunctional vehicle

Abstract

This invention discloses a self-propelled CNG recovery multi-functional vehicle, belonging to the technical field of natural gas extraction and recovery equipment. It includes a vehicle chassis, a skid platform, a compressor, a purification and treatment device, a control device, and a filling device. The skid platform is fixed to the vehicle chassis and integrates a compressor, an air cooler, a buffer separation unit, a drying tower (forming a purification and treatment device), and a dual-nozzle refueling column. The chassis engine drives the compressor via a power take-off and a torque box. The control device enables fully automatic monitoring. This invention highly integrates complete CNG recovery and purification functions into a self-propelled vehicle, enabling rapid deployment, on-site pressurization, deep dehydration, and compliant filling of natural gas from scattered wells. It features high integration, strong mobility, complete functionality, low operating costs, and high safety and reliability, making it particularly suitable for the natural gas resource recovery operations of marginal and scattered wells.

Description

Technical Field

[0001] This invention relates to the field of natural gas extraction and recovery equipment technology, and in particular to a self-propelled CNG recovery multi-functional vehicle. Background Technology

[0002] With the development of unconventional natural gas resources, the number of scattered gas wells, marginal wells, and low-pressure wells is increasing. These wells have low production and insufficient pressure, making them difficult to connect to pipeline networks. However, direct venting or incineration would result in resource waste and environmental pollution. Therefore, on-site recovery, purification, and compression of this type of scattered natural gas into compressed natural gas (CNG) for transportation or direct filling is an effective way to improve resource utilization and reduce emissions.

[0003] Currently, the relevant technologies involving vehicle-mounted natural gas processing equipment mainly suffer from the following shortcomings: Limited functionality and inability to achieve resource utilization: Existing mobile natural gas equipment often focuses on a single operation. For example, Chinese patent CN117759205A discloses a "natural gas lift and drainage equipment for a vehicle-mounted natural gas engine direct-drive compressor," designed to inject compressed high-pressure natural gas into the wellbore for gas lift and drainage. The process endpoint is the oil / casing, lacking deep dehydration and purification processes for the natural gas. Furthermore, these existing technologies do not address how to process the natural gas into products that meet the requirements of commercial compressed natural gas for sale, transportation, or direct filling. Their system endpoints are primarily the wellbore's tubing or casing, and the overall process flow does not disclose a complete processing chain for compressed natural gas after deep dehydration, metering, and safety shut-off before entering a standardized CNG filling interface. Nor does it disclose a centralized quick-disassembly interface area that coordinates with wellhead gas access, drainage, and gas lift operations. Therefore, such equipment is difficult to directly apply to the resource recovery of natural gas from scattered gas wells and on-site CNG filling scenarios.

[0004] Limited mobility due to reliance on external infrastructure: Some mobile CNG equipment still requires on-site mains power or large diesel generator sets for power supply, or needs to be installed on a fixed concrete foundation. This not only increases deployment time and cost, but also limits its rapid application in scattered well sites with no mains power and poor site conditions.

[0005] Low system integration and low relocation efficiency: In traditional solutions, modules such as compressor, cooling, separation, dehydration and control may be placed on multiple skids or require a large number of pipelines to be connected on site. During relocation, multiple vehicles are needed for transportation, multiple hoisting and complex on-site installation and commissioning. It cannot achieve "ready to use" and is not suitable for the intermittent and multi-point operation characteristics of scattered gas wells.

[0006] Uneconomical energy utilization: Some vehicle-mounted equipment uses independent diesel or gas engines to power the compressor, which increases additional fuel consumption, maintenance costs and exhaust emission points, and fails to make full use of the vehicle chassis' own power source. The system's energy efficiency needs to be optimized. Summary of the Invention

[0007] The purpose of this invention is to provide a self-propelled multi-functional CNG recovery vehicle, the core objective of which is to solve the problem of the inability to economically, efficiently, and quickly recover natural gas from scattered gas wells and convert it into qualified commercial CNG. Specific objectives include: This invention provides a highly integrated, self-propelled CNG recovery system that eliminates the need for fixed foundations and external power supplies, enabling rapid deployment.

[0008] A complete on-board purification and treatment chain integrating pressurization, cooling, gas-liquid separation, and deep dehydration is constructed to ensure that the quality of the produced gas directly meets the CNG filling standards.

[0009] The power system is optimized by utilizing the power of the vehicle chassis engine to directly drive the compressor via a power take-off unit, achieving power self-sufficiency and reducing operating energy consumption and complexity.

[0010] It adopts modular and standardized quick-connect interfaces and intelligent control systems to reduce the difficulty of operation, improve the safety and automation level of operation, and adapt to the operation mode of unattended or short-term inspection in the field.

[0011] This invention is achieved using the following technical solution: a self-propelled CNG recovery multi-functional vehicle, comprising a vehicle chassis; a skid platform rigidly fixed to the vehicle chassis; a compressor mounted on the skid platform; a purification and treatment device mounted on the skid platform, which sequentially includes an air cooler, a buffer separation unit for gas-liquid buffer separation, and a drying tower connected by interconnected pipelines along the natural gas flow path; the inlet of the air cooler connected to the outlet pipeline of the compressor; and the outlet of the drying tower being the product gas outlet; a control device mounted on the skid platform and electrically connected to the compressor and the controlled components of the purification and treatment device; and a filling device mounted on the skid platform, wherein the filling device is a dual-nozzle gas filling column, and the inlet of the dual-nozzle gas filling column is connected to the product gas outlet pipeline of the drying tower.

[0012] Furthermore, it also includes a power transmission system, which includes a power take-off (PTO) and a torque converter. The PTO is used to connect to the engine power output side of the vehicle chassis. The input end of the torque converter is connected to the output end of the PTO. The output end of the torque converter is driven to the input end of the compressor through a transmission mechanism.

[0013] Furthermore, the buffer separation unit includes an inlet buffer tank and a sludge collection tank. The inlet of the inlet buffer tank is connected to the outlet pipe of the air cooler, the sludge collection tank is connected to the liquid phase outlet pipe at the bottom of the inlet buffer tank, and the inlet of the drying tower is connected to the gas phase outlet pipe at the top of the inlet buffer tank.

[0014] Furthermore, the skid platform also integrates an engine parking radiator, which is used to connect to the engine circulating cooling water circuit of the vehicle chassis to dissipate heat from the engine during parking operation.

[0015] Furthermore, the side or end of the skid platform is centrally arranged with a quick-release interface area for connecting with external process pipelines. The quick-release interface area includes at least an air inlet, an air lift outlet, and a drain outlet, wherein the air inlet is used to connect to wellhead gas via a process hose, and the drain outlet is connected to the sewage discharge pipeline of the sludge collection tank.

[0016] Furthermore, each interface in the quick-release interface area adopts a union connector or a compression fitting quick connector, and a manual shut-off valve or a pneumatic shut-off valve is respectively provided on the upstream side of the interface.

[0017] Furthermore, the control device is an explosion-proof control cabinet integrating a PLC controller and a touch screen. Pressure transmitters, temperature sensors, and vibration sensors are also arranged on the skid platform. The signal cables of each sensor are introduced into the control device, and the PLC controller performs operation monitoring and safety interlock control.

[0018] The self-propelled CNG recycling multi-functional vehicle described in this invention has the following advantages: The entire CNG recovery and purification process is integrated into a skid platform rigidly fixed to a vehicle chassis, forming a true mobile factory. When the equipment is moved, there is no need for hoisting or external power supply. It can travel to the new well location using the chassis' own power. Once the outriggers are lowered on a leveled site, operations can begin. Deployment time is reduced from several days to several hours, greatly improving the efficiency of recovery operations for scattered and remote gas wells.

[0019] Innovatively, a complete purification chain, from compressor, air cooler, intake buffer tank to drying tower, is integrated into the vehicle space. In particular, the introduction of the drying tower enables deep dehydration of natural gas, ensuring that key indicators such as water dew point of the produced gas stably meet the national standards for commercial CNG. The gas is then directly filled into transport tankers or vehicles through a dual-nozzle filling column.

[0020] The power transmission system, consisting of a power take-off and a torque converter, cleverly utilizes the chassis engine of the recycling vehicle to power the compressor, eliminating the need for a separate drive engine or high-power generator. This not only reduces equipment manufacturing costs and weight, and decreases fuel consumption and emissions, but also achieves a self-closing power system, making it particularly suitable for using recycled natural gas as fuel, further reducing operating costs.

[0021] The system employs a PLC-based control device to provide real-time monitoring and automatic protection for compressor operating parameters, process pipeline pressure and temperature, container liquid levels, and equipment vibration throughout the entire process. If any parameter exceeds limits, the system can automatically execute protective actions such as shutdown and venting, significantly reducing safety risks caused by human error or delayed detection. This ensures the reliability of long-term stable, unattended operation of the equipment in harsh outdoor environments.

[0022] The quick-release interface area (including air inlet, gas lift inlet, and liquid outlet) is centrally located on the side of the skid platform, using union or compression fittings to achieve rapid connection and disconnection with well site facilities. Combined with the function of performing gas lift operations on the wellbore, this vehicle can not only recover natural gas but also assist in well production recovery, making it a multi-functional unit that significantly improves the overall effectiveness and market adaptability of the equipment.

[0023] The dual-nozzle gas column integrates a mass flow meter, pressure sensor, safety valve, and pneumatic shut-off valve, enabling the metering, pressure detection, safe release, and shut-off control of dried high-pressure natural gas, allowing the purified product gas to directly enter the on-site filling process.

[0024] When pressure, temperature, vibration, or liquid level parameters exceed preset safety thresholds, the control device can perform cascaded protection actions such as audible and visual alarms, emergency venting, compressor shutdown, and power take-off disengagement, thereby forming interlock protection between the vehicle's power transmission system, compression system, purification system, and filling system.

[0025] After the gas lift port is connected to the compressor stage pipeline through a valve, it can supply gas to the wellbore using the high-pressure gas source generated by the compressor when gas lift liquid discharge is required; after the liquid discharge port is connected to the sewage discharge pipeline of the sewage collection tank, it can centrally discharge the liquid hydrocarbons and sewage collected during the gas intake buffer separation process, thereby improving the synergy of well site access, gas lift assistance and sewage treatment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a front view of the overall structure of the present invention; Figure 2 This is a top view of the overall structure of the present invention; In the diagram, 1-Power take-off, 2-Torque box, 3-Engine parking radiator, 4-Compressor main unit, 5-Air cooler, 6-Intake buffer tank, 7-Sludge collection tank, 8-Drying tower, 9-Drain port, 10-Electrical distribution cabinet, 11-Control cabinet, 12-Dual-nozzle air supply column. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example 1: like Figure 1-2 As shown, this embodiment provides a self-propelled CNG recycling multi-functional vehicle, mainly composed of a vehicle chassis, a skid platform, a compressor 4, a purification and treatment device, a control device 11, and a filling device 12. The skid platform is rigidly fixed to the subframe beam of the vehicle chassis by high-strength bolts, forming a non-removable integrated vehicle unit. The compressor 4, purification and treatment device, control device 11, and filling device 12 are all integrated and installed on the skid platform.

[0031] Specifically, the vehicle chassis uses a natural gas (CNG) engine as its power source. A power take-off (PTO) 1 is connected to the rear end of the engine's gearbox via a flange. The output shaft of the PTO 1 is connected to the input end of a torque converter 2 via a diaphragm coupling. The torque converter 2 is used to increase the output torque and adjust the output speed. Its output end is directly driven by a transmission mechanism consisting of a universal joint and a drive shaft, directly driving the input end of the compressor 4's main shaft. This allows the power from the vehicle chassis engine to be directly transmitted to the compressor 4, achieving self-sufficiency in power without the need for an external electric motor or generator.

[0032] The purification and treatment unit is integrated sequentially on a skid-mounted platform along the natural gas process flow. The outlet of compressor 4 is connected to the inlet of an air cooler 5 via a high-pressure alloy steel pipe. The air cooler 5 adopts a combined wound finned air-cooled structure, and its outlet is connected to the top inlet of an inlet buffer tank 6. The bottom liquid phase outlet of the inlet buffer tank 6 is connected to a sludge collection tank 7 via a pipeline. The top gas phase outlet of the inlet buffer tank 6 is connected to the inlet of a drying tower 8 via a pipeline. The drying tower 8 is a dual-tower structure, filled with molecular sieve adsorbent. The two towers automatically switch between adsorption and regeneration processes via program-controlled valves. The dry gas outlet of the drying tower 8 is the final outlet of the purification and treatment unit.

[0033] The control device 11 is an integrated explosion-proof control cabinet. Its core is a PLC controller, and it also integrates a touch screen, relays, a power module, and a signal conditioning module. The control cabinet is connected via shielded cables to various sensors distributed throughout the skid, including but not limited to pressure transmitters, temperature sensors, vibration sensors, and level detection elements for monitoring the air intake buffer tank 6 and the sludge collection tank 7. The signal cables of each sensor element are all led into the control device (11). It is also connected to actuators (including but not limited to pneumatic ball valves, regulating valves, and compressor loading solenoid valves) to form a complete monitoring and control loop.

[0034] The filling device 12 is a dual-nozzle gas column, whose inlet is directly connected to the drying gas outlet of the drying tower 8 via a high-pressure rigid pipe. The gas column integrates a high-precision mass flow meter, a pressure sensor, a safety valve, and a pneumatic shut-off valve.

[0035] On the side of the skid platform, a quick-release interface area for connecting to external process pipelines is centrally located. This area includes at least: an air inlet, connected to the quick-connect flange of the wellhead pretreatment unit via a high-pressure hose; an air lift port, connected to the compressor interstage pipeline via a valve, for air lift operations on the wellbore when necessary; and a drain port, connected to the drain valve outlet of the sludge collection tank 7, for periodic discharge of collected liquid hydrocarbons and wastewater. All quick-release interfaces use unibody or compression fitting quick-connect types, and each interface's upstream pipeline is equipped with a manual or pneumatic shut-off valve.

[0036] The working principle and process of this embodiment are as follows: When it is necessary to move from the current well site to the next, the operator first executes the shutdown procedure through control device 11, sequentially shutting down compressor 4 and process valves, and depressurizing the system. Then, the operator manually disconnects the quick-release connections between the air inlet, gas lift inlet, and wellhead equipment, and closes the drain valve. After these operations are completed, the entire processing unit integrated on the skid platform functions as a vehicle-mounted unit. The driver operates the chassis, which travels under its own power to the flat, hardened ground of the target well site without any lifting equipment or pre-cast concrete foundations. After parking, the vehicle is leveled and stabilized using the chassis's hydraulic outriggers or mechanical support devices, thus completing the positioning process.

[0037] After the vehicle is in place, the chassis engine is started. When it is necessary to start the compressor 4, the pneumatic or electronic engagement mechanism of the power take-off (PTO) 1 is controlled via the control device 11 or a command from the chassis operating panel, engaging the PTO 1 with the power output shaft of the engine transmission. The engine's power is transmitted sequentially through the PTO 1 and the drive shaft to the torque converter 2. After torque amplification and speed regulation by the torque converter 2, it ultimately drives the main shaft of the compressor 4 to rotate. The engine's circulating cooling water is distributed through pipelines to a dedicated engine parking radiator 3, which is cooled by an independent fan, ensuring that the engine can continuously provide power to the compressor even when parked.

[0038] After pretreatment, the wellhead natural gas enters the unit through the quick-release inlet. The gas first enters compressor 4, where it is compressed to the target pressure in stages. The high-temperature gas generated during compression exits from compressor 4 and enters air cooler 5, where it exchanges heat with air under the action of a cooling fan, reducing its temperature to the required range. The cooled gas then enters inlet buffer tank 6, achieving preliminary gas-liquid separation and buffering gas flow pulsations; the separated droplets settle to the bottom of the tank and are periodically discharged into collection tank 7. The separated gas phase enters drying tower 8 from the top of inlet buffer tank 6, where moisture is deeply removed by molecular sieve adsorbent, bringing the gas water dew point to below -55℃. The dried, qualified high-pressure natural gas is finally delivered to dual-nozzle filling column 12, awaiting filling.

[0039] Throughout the entire operation, control device 11 operates continuously. Its PLC controller executes three levels of control logic: Signal acquisition: The PLC acquires in real time the intake pressure, exhaust pressure of each stage, machine vibration value, lubricating oil temperature and pressure from compressor 4 through the analog input module; acquires the temperature signal from air cooler 5 and process pipeline; acquires the liquid level signal from intake buffer tank 6 and sludge collection tank 7; and acquires the pressure and flow signal from air filling column 12.

[0040] Threshold comparison: The PLC has preset multiple safety protection thresholds, including upper and lower pressure limits, upper temperature limits, vibration alarm values, and high and low liquid level limits.

[0041] Logical execution: Upon receiving the start command, the PLC automatically turns on the fan and opens the bypass valves at each stage according to the preset sequence, and coordinates with the chassis to control the PTO 1 to engage, driving the compressor 4 to start under no-load conditions, and then gradually loads according to the logic; all collected parameters are displayed on the touch screen in real time and uploaded to the remote monitoring center through the communication module; when any parameter exceeds its safety threshold, the PLC immediately outputs a signal to execute cascade protection actions of audible and visual alarm, emergency venting, compressor shutdown, and PTO disengagement to ensure system safety; the PLC automatically controls the opening and closing of the drain valve of the sludge collection tank 7 according to the liquid level signal or timer setting to achieve automatic liquid level management.

[0042] The touchscreen of control device 11 continuously displays key operating parameters, such as real-time production, cumulative production, inlet pressure, and operating time. Operators make a comprehensive judgment based on three pre-set manual observation thresholds: the lower limit of wellhead pressure, the cumulative production threshold for a single well, and a significant increase in wellhead water production. When any threshold is reached, it indicates that the well is no longer economically viable or requires protective shut-in. Operators then follow the aforementioned "relocation and positioning" process, manually deciding and executing the shut-in, dismantling, and transfer to the next well, thus achieving standardized and orderly rotation and recovery operations for multiple scattered gas wells within the area.

[0043] This embodiment achieves the following beneficial effects through the specific structural design described above: High integration and self-propelled: The entire CNG recycling process is integrated into a skid that is rigidly fixed to the vehicle chassis, enabling the equipment to move on its own. This completely eliminates the dependence on cranes, transport trucks, and fixed concrete foundations, resulting in extremely high relocation efficiency.

[0044] Power self-sufficiency and simplification: The innovative system utilizes the chassis engine to directly drive the compressor 4 through the power take-off 1 and torque box 2, eliminating the need for a separate diesel generator set or high-power electric motor, simplifying the system, reducing energy consumption and space occupation, and using recovered CNG as fuel to achieve energy closed loop.

[0045] Rapid deployment: Standardized quick-release interfaces greatly reduce the workload and time of on-site pipeline connections. Combined with the self-propelled function, the equipment can complete the conversion and commissioning between different well sites in a very short time.

[0046] Fully automated monitoring and inherent safety: The integrated PLC control system achieves full automation from one-button start / stop and process monitoring to multiple safety interlocks, reducing the difficulty of operation and the risk of human error, and ensuring the safety and reliability of operations in harsh field environments.

[0047] The process chain is complete and efficient: from compression, cooling, separation to deep dehydration, all processing units are compactly arranged and seamlessly connected to form an efficient and complete on-board processing chain, ensuring that the CNG produced directly meets the standards for filling or reuse.

[0048] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Modifications and variations made by those skilled in the art without departing from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. A self-propelled CNG recycling multi-functional vehicle, characterized in that, The system includes a vehicle chassis; a skid platform rigidly fixed to the vehicle chassis; a compressor (4) mounted on the skid platform; a purification and treatment device mounted on the skid platform, which includes, along the natural gas flow path, an air cooler (5) connected to each other by pipelines, a buffer separation unit for gas-liquid buffer separation, and a drying tower (8). The inlet of the air cooler (5) is connected to the outlet pipeline of the compressor (4), and the outlet of the drying tower (8) is the product gas outlet. The inlet of the compressor (4) is used to connect to the wellhead gas input pipeline, which is connected to the wellhead gas through a quick-release interface area located on the side or end of the skid platform; a control device (11) mounted on the skid platform and electrically connected to the compressor (4) and the controlled components of the purification and treatment device; and a filling device (12) mounted on the skid platform, which is a dual-nozzle gas filling column, the inlet of which is connected to the product gas outlet pipeline of the drying tower (8).

2. The self-propelled CNG recycling multi-functional vehicle according to claim 1, characterized in that, It also includes a power transmission system, which includes a power take-off (1) and a torque box (2). The power take-off (1) is used to connect to the engine power output side of the vehicle chassis. The input end of the torque box (2) is connected to the output end of the power take-off (1). The output end of the torque box (2) is driven to the input end of the compressor (4) through a transmission mechanism. The transmission mechanism includes at least one of a coupling, a universal joint, and a drive shaft.

3. The self-propelled CNG recycling multi-functional vehicle according to claim 2, characterized in that, The buffer separation unit includes an air inlet buffer tank (6) and a sludge collection tank (7). The inlet of the air inlet buffer tank (6) is connected to the outlet pipe of the air cooler (5). The sludge collection tank (7) is connected to the liquid phase outlet pipe at the bottom of the air inlet buffer tank (6). The inlet of the drying tower (8) is connected to the gas phase outlet pipe at the top of the air inlet buffer tank (6). The drying tower (8) is a double tower structure, filled with molecular sieve adsorbent. The two towers switch between the adsorption process and the regeneration process through a program-controlled valve.

4. The self-propelled CNG recycling multi-functional vehicle according to claim 1, characterized in that, The skid platform is also integrated with an engine parking radiator (3), which is used to connect to the engine circulating cooling water circuit of the vehicle chassis to dissipate heat from the engine during parking operation.

5. A self-propelled CNG recycling multi-functional vehicle according to claim 1, characterized in that, The side or end of the skid platform is centrally arranged with a quick-release interface area for connecting with external process pipelines. The quick-release interface area includes at least an air inlet, an air lift inlet and a drain outlet. The air inlet is used to connect to wellhead gas via a process hose. The drain outlet is connected to the sewage discharge pipeline of the sludge collection tank (7). The filling device (12) integrates a mass flow meter, a pressure sensor, a safety valve and a pneumatic shut-off valve.

6. A self-propelled CNG recycling multi-functional vehicle according to claim 5, characterized in that, Each interface in the quick-release interface area adopts a union joint or a compression fitting quick-release connector, and a manual shut-off valve or a pneumatic shut-off valve is respectively provided on the upstream side of the interface.

7. A self-propelled CNG recycling multi-functional vehicle according to claim 1, characterized in that, The control device (11) is an explosion-proof control cabinet integrating a PLC controller and a touch screen. Pressure transmitters, temperature sensing elements and vibration sensing elements are also arranged on the skid platform. The signal cables of each sensing element are introduced into the control device (11) and the PLC controller performs operation monitoring and safety control.

8. A self-propelled CNG recycling multi-functional vehicle according to claim 5, characterized in that, The gas lift port is connected to the interstage pipeline of the compressor (4) via a valve and is used to perform gas lift operations on the wellbore.

9. A self-propelled CNG recycling multi-functional vehicle according to claim 1, characterized in that, The skid platform is also equipped with a liquid level detection element, and the signal cable of the liquid level detection element is introduced into the control device (11); the PLC controller is configured to output a control signal to perform cascade protection actions such as audible and visual alarm, emergency venting, compressor shutdown and power take-off disengagement when the pressure, temperature, vibration or liquid level parameters exceed the preset safety threshold.

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