What is a Liquid-Driven CNG Substation Compressor?
A liquid-driven CNG substation compressor, also known as a hydraulic-driven natural gas compressor, is core compression equipment built for CNG refueling substations. It uses hydraulic power to drive cylinder compression, transferring high-pressure natural gas from CNG transport trailers into vehicle cylinders for buses, trucks and commercial fleets.
Unlike traditional reciprocating gas compressors, liquid-driven compressors adopt a hydraulic reciprocating two-acting cylinder structure. This innovative design solves common pain points of conventional compression equipment: high wear, frequent maintenance, high energy consumption and short service life.
An integrated liquid-driven CNG substation compressor further integrates unloading columns, compression units, gas cylinder groups and dispensers into one skid or containerized package. This all-in-one layout cuts site construction work, shortens commissioning cycles and fits containerized turnkey CNG station projects, which is increasingly popular for global overseas gas station construction.
Our brand is one of China's earliest independent R&D manufacturers for large-displacement liquid-driven natural gas compressors. We developed China's first 4500Nm³ and 4800Nm³ liquid-driven compressors, with export-ready customized solutions launched since 2024.
How Does a Liquid-Driven CNG Substation Compressor Work?
The core component is the three-section compression cylinder. A single cylinder can realize two-stage natural gas compression. The cylinder chamber is split into independent gas compression cavities and hydraulic oil cavities, completely isolating gas and hydraulic oil with multi-level sealing.
The full working flow breaks down into 3 simple steps:
The motor drives the hydraulic oil pump to deliver hydraulic oil;
The integrated reversing system pushes the piston to reciprocate inside the cylinder;
Dual-side cylinder chambers continuously compress natural gas without gas-oil mixing, even if partial sealing leakage occurs.
For a complete CNG substation refueling process:
CNG trailers deliver compressed natural gas as the low-pressure gas source;
Gas flows through pipelines into medium-pressure and high-pressure bottle groups controlled by a PLC system;
When trailer and bottle group pressure cannot meet vehicle refueling requirements, the liquid-driven compressor automatically starts to refill high-pressure cylinder groups;
High-pressure gas flows into dispensers to fill natural gas vehicles.
The whole system makes full use of residual high-pressure energy from CNG trailers, reducing compressor startup frequency and power consumption.
Two Main Types of Integrated Liquid-Driven CNG Substation Compressors
Integrated skid designs are divided into fully integrated type and general integrated type to match different site conditions.
1： Fully Integrated Type
This package integrates unloading column, compressor, gas cylinder group and gas dispenser in one set.
High integration, simple on-site fixing, ready for commissioning once installed
Standard overall length around 9m, compatible with 40ft high cube containers
Best for sites with limited land area and fast construction schedules
2: General Integrated Type
It combines two or three modules among unloading column, compressor and bottle groups.
Flexible layout and small footprint
Gas dispensers can be installed separately for safer and more convenient refueling operation
Suitable for large CNG stations with multiple refueling machines
Core Technical Advantages of Liquid-Driven Compressors vs Traditional Compressors
Many station investors compare liquid-driven compressors with conventional reciprocating compressors and ordinary liquid-driven models. Liquid-driven CNG substation compressors show clear long-term economic benefits:
Lower overall operation cost The moving parts are only pistons and piston rods, with no direct metal friction. Wearing sealing parts account for only 10%~20% of spare part consumption compared with traditional reciprocating compressors. Vertical cylinder mounting prevents sealing deflection and extends sealing service life.
Dual-system optional design Dual independent systems can run simultaneously or act as mutual backup. Single system operation provides half of the total displacement, which guarantees continuous gas supply during equipment maintenance, avoiding station shutdown losses.
Support no-load startup & frequent start-stop Hydraulic control separates motor operation and cylinder compression. Operators do not need to exhaust high-pressure gas inside cylinders before startup, saving power and improving working efficiency.
Low failure rate & long service life Low linear speed of sealing rings reduces abrasion; the hydraulic system bears lower load with stable long-time running performance. Our field units have achieved cumulative operating hours over 11,000 hours in domestic projects.
Key Technical Parameters Reference
Common models cover displacement from 600Nm³/h to 2500Nm³/h to satisfy different station throughput demands:
Compressed medium: Natural gas (Class II standard GB17820)
Inlet pressure: 3–20 MPa
Outlet pressure: ≤25 MPa
Compression: Two-stage compression
Power options: 30KW / 37KW / 45KW / Dual 30/37/45KW
Control system: Explosion-proof control cabinet
Typical Application Scenarios of Liquid-Driven CNG Substation Compressors
✅ CNG refueling substations for buses, heavy trucks, fleets and commercial vehicles ✅ Containerized skid-mounted CNG station turnkey projects ✅ Natural gas long-distance transmission booster stations ✅ CNG mother station gas compression ✅ Overseas gas station EPC & export projects
Why Choose Our Liquid-Driven CNG Substation Compressor?
Leading domestic manufacturer in hydraulic-driven compressor technology, independent R&D with complete patent protection for large-displacement models
Under the same power configuration, our compressors realize larger displacement and lower unit gas consumption
Verified stable operation data from thousands of running hours on domestic projects
Customized integrated skid and containerized solutions for global customers, official export service available since 2024
Complete technical support for overseas installation, commissioning and after-sales guidance
Frequently Asked Questions (FAQ)
Q1: Is liquid-driven CNG compressor oil-free?
A1: Yes. The gas cavity and hydraulic oil cavity are fully separated with multi-stage sealing, no oil will mix into compressed natural gas.
Q2: Can the integrated compressor be loaded into a shipping container for export?
A2: The fully integrated type can be fitted inside a standard 40ft high cube container, convenient for sea transportation and fast on-site deployment.
Q3: Can we customize the displacement and power according to our station design?
A3: Customization is supported. We provide tailored skid layout, power configuration and bottle group parameters for different country standards and project requirements.
