Container CNG Compressor, Home Filling Station, Petrol-Station Container and LNG Compressor Package

A containerized natural gas fueling package can be configured as a CNG compressor station, a small home/private filling unit, a petrol-station CNG module, or an LNG/L-CNG station. These are not the same technology. CNG uses high-pressure gas compression, normally up to 20–25MPa for vehicle filling; LNG uses cryogenic liquid storage at about -162°C and is handled with pumps, vaporizers and insulation rather than a conventional "air compressor." A combined L-CNG container can receive LNG, pump it at high pressure, vaporize it and fill CNG vehicles through storage cascades.

This guide separates the four scopes so the station can be specified correctly by flow, inlet pressure, discharge pressure, vehicle type, site safety class and fuel mix.

1. CNG Container Compressor Station — Core Concept

A container CNG compressor station receives pipeline gas, station gas from a low-pressure network, or gas from a CNG tube trailer, then compresses it into high-pressure storage and dispensers. Typical vehicle filling pressure is 20MPa for some regional/Ngv1 light-duty norms, 25MPa for standard CNG station compressors in many projects, and up to about 25–30MPa depending on local vehicle and cylinder standards. One supplier range lists mother-station compressors to 3600Nm³/h at 25MPa, standard stations to 1800Nm³/h, substations to 1400Nm³/h and home units around 50Nm³/h.

A container or skid module usually integrates:

• Gas inlet filtration, metering and pressure regulation

• Pre-compression dehydration/dryer to control water dew point and avoid compressor icing

• Reciprocating, high-speed reciprocating, screw or hydraulic booster compressor

• Intercooling/aftercooling, moisture separation

• High-pressure buffer cylinders or cascade storage

• Priority/sequence control panel

• Dispenser(s) with mass flow meter, breakaway, NGV nozzle

• PLC/HMI, gas detection, ESD, ventilation, explosion-protected electricals

Factory-integrated skids can be landed on hardened ground, connected to power and gas source, and commissioned in a few days for simple modules; larger container systems need formal leak test, purge, electrical inspection and authority approval.

2. Home Filling / Small Private CNG Station

Home or private CNG filling is used for a single vehicle, household fleet, farm trucks, shuttle vans or depot cars. It does not need a public petrol-station layout.

Selection guidance places home/small private stations at roughly 50–300Nm³/h; medium commercial/public stations at 300–1200Nm³/h; large mother stations above 1200Nm³/h, with some mother units up to 3600Nm³/h. For home use, time-fill is safest and cheapest because it allows a smaller compressor, lower motor power and less thermal/stress on storage. Fast-fill at home requires larger compressor, bigger cascade and stricter safety zoning.

A home container should include odorized/approved gas compliance, inlet dryer, overpressure protection on every stage, emergency shutoff, outdoor ventilation, combustible-gas detection and a dispenser rated for the vehicle nozzle standard in the target country.

3. Petrol-Station / Public Container CNG Module

Adding CNG to an existing petrol station requires separate hazardous-area classification for natural gas. A 20ft or 40ft container can house the compressor, dryer, electrical room and cascade, while dispensers may be installed at the container wall or as separate island units.

Example plug-and-play reference: a 20ft ISO container with high-speed reciprocating compressor up to 400HP, four-stage compression, inlet gas dryer with dew-point meter/alarm, gas cooler, cascade buffer vessels, PLC station control, soft starter/UPS and dispenser option; published box sound level under 80dBA at 10ft and operating range -4°F to 110°F, with discharge capability up to 4700psig depending on configuration. Another mobile/daughter product uses suction 3–20MPa, discharge ≤25MPa, about 1200Nm³/h average, two-stage, motor-driven hydraulic oil-free design, PLC touchscreen and skid dimensions about 6.3×2.18×2.32m at ≤65kW.

For a petrol station retrofit:

• Confirm station layout separation between petroleum fuels and CNG cylinders/compressor per local fire code.

• Use explosion-protected motors, sensors, lights and panels; reference ATEX/IECEx or local equivalent for gas area.

• Install gas detection at compressor, buffer, dispenser and container low points; link to ESD.

• Size storage cascade by peak vehicles per hour, not only daily volume. A fast-fill public station needs much larger high-pressure storage than a time-fill fleet station.

• Provide priority sequencing so compressor first fills high-pressure cascade, then mid/low, reducing wait and compressor cycling.

4. LNG Compressor vs CNG Compressor — Do Not Mix

Many buyers search "container LNG compressor" but LNG stations do not use a high-pressure gas compressor in the same way as CNG.

CNG is typically compressed to reduce volume substantially at high pressure; LNG is cooled to reduce volume by roughly 600× at cryogenic temperature. For off-grid or long-distance supply, LNG often wins on delivery density; for pipeline-connected, urban or medium-demand sites, CNG containers are usually simpler and faster.

An L-CNG container can convert LNG to CNG: LNG storage tank → cryogenic/submerged pump → high-pressure vaporizer → sequence panel → CNG storage → CNG dispenser. One sample L-CNG configuration uses a 60m³ 1.2MPa LNG tank, submerged pump skid, 1500L/h high-pressure plunger pumps, 1500Nm³/h vaporizers, sequence panel 2000Nm³/h, 1.33m³×6 cylinder group and two CNG dispensers, plus LNG dispensers, EAG heaters, PLC, gas/flame detection and instrument-air system. This is the correct "LNG compressor station" interpretation if the output is CNG vehicles.

5. Compressor Type Selection for Container CNG

Practical rules: each stage pressure ratio commonly around 3–4 and generally not exceeding about 7 in CNG piston design; multiple stages are used for large overall ratios from low pipeline inlet to 25MPa. If inlet is already 3–20MPa from a tube trailer, a daughter container can use a smaller booster or hydraulic pump instead of a full multistage compressor. If inlet is 0.2–0.4MPa pipeline, a full multistage reciprocating or HSR package is required.

6. Container System Configuration by Station Type

Home/private container

• Inlet regulator/filter, low-capacity dryer

• 50–150Nm³/h oil-free or micro-oil reciprocating, electric

• Small intercooler/aftercooler

• 1–2 stage cascade or single buffer cylinder set

• One time-fill hose or small dispenser

• PLC with pressure/dew-point/alarm, basic gas detection, outdoor enclosure

• 10ft/compact 20ft acoustic container

CNG daughter/substation container

• Tube-trailer unload connection, meter

• Suction 3–20MPa option or lower; booster/reciprocating/hydraulic to ≤25MPa

• 600–1400Nm³/h typical; example 1200Nm³/h average, ≤65kW hydraulic oil-free skid

• Buffer cylinders, sequence panel

• 1–2 dispensers, PLC, ESD, gas detection

• 20ft–40ft depending on storage volume

Standard/pipeline CNG container

• Pipeline inlet filtration, metering, regulator

• Pre/inline dehydration

• Reciprocating 300–1800Nm³/h at 25MPa; larger if duty requires

• Intercooling, aftercooling, separators

• Cascade storage sized by peak hourly vehicles

• Fast-fill dispensers, priority panel, IC/card option

• Explosion-proof electrical, ventilation, fire/leak detection

Mother station container/central package

• High pipeline inlet 1–4MPa or 9MPa in some transmissions

• Large reciprocating/screw-assisted trim, 2400–3600Nm³/h+

• Continuous-duty cooling, oil/system analysis, dual electrical feeds

• Cascade plus tube-trailer filling

• Redundant compressors, full SCADA, advanced ESD

L-CNG container

• LNG tank, submerged pump, high-pressure plunger pumps

• Vaporizers, EAG/heater, sequence panel

• CNG cylinder group, CNG dispensers, optional LNG dispensers

• Cryogenic instrumentation, vacuum-line integrity, boil-off control

• PLC, gas/flame detection, separate electrical/cryo safety zones

7. Drying, Gas Quality and Dew Point

Wet natural gas causes compressor valve fouling, ice/hydrate plugging and dispenser failure at high pressure. CNG station design normally includes dehydration before or around compression. One mother-station guide recommends low-pressure pre-dehydration for high-inlet mother plants because pressure drop is less punishing and daily volume is large; daughter/standard stations select dryer location by inlet pressure, flow and compressor protection. Vehicle CNG quality standards such as GB 18047 define fuel specifications for vehicles; station design should match local vehicle-fuel standard for sulfur, H2S, particles, oil, CO2 and water dew point.

For container units:

• Pipeline gas: filter coalescing/dry particulate, analyze water dew point, install desiccant or glycol/twin-tower dryer sized to inlet flow.

• Trailer gas already dehydrated at mother station may need only filtration and pressure control, but verify dew point after pressure letdown.

• L-CNG: LNG source is essentially dry after liquefaction, but vaporizer/ambient air can re-introduce moisture in outer lines; instrument-air and CNG lines should be separately controlled.

• Record dew point at compressor outlet and dispenser inlet; alarm on deviation.

8. Safety, Codes and Container Design

CNG is high-pressure flammable gas; LNG adds cryogenic and asphyxiation hazards. A container station must be specified, not improvised.

Key safety elements:

• Hazardous-area electrical classification and explosion-protected equipment; ATEX/IECEx or local equivalent for gas areas.

• Multilevel protection: overpressure relief on each stage, buffer and dispenser line; overtemperature; overvibration; low lubrication/oil differential; low cooling; gas leak detection.

• Combustible gas detectors at low points, compressor bay, storage and dispenser zone; automatic ESD and ventilation trip.

• Pressure relief devices sized to stage/storage; discharge to safe outdoor location per code.

• Separate airflow for electrical room and compressor bay; positive ventilation for gas-containing enclosure; emergency stop inside/outside.

• Fire detection/extinguishing option, flame detection for LNG/petrol hybrid sites.

• Pressure vessels and piping to ASME/EN/GB/local code; cylinders certified for CNG service; cryogenic tanks vacuum-insulated and qualified for LNG.

• ISO 16923 covers CNG vehicle fueling-station design, risk management, compressors, storage, dispensers, detection and ESD; local national standards may adopt or extend it. Chinese draft national CNG station rules modify/adopt ISO 16923 and detail dryers, compressor, buffer storage, dispensers, odorization, gas detection and ESD. Fire-code references for CNG motor-fuel facilities address above-grade outdoor equipment, emergency shutoff distance, ventilation in repair garages and ASME pressure-vessel relief.

For home stations, even if small, do not place the compressor indoors with living spaces. Use outdoor container/skid, locked enclosure, detected leaks, separated electrical and local fire-department-approved layout.

9. Sizing Method for a Container CNG Proposal

1. Define vehicles: number, type, cylinder pressure rating, NGV nozzle standard, daily km and gas consumption.

2. Convert daily gas need to Nm³; add weekend/peak buffer.

3. Define filling mode: time-fill reduces compressor size; fast-fill increases compressor and cascade.

4. Record inlet pressure range minimum/normal/maximum; calculate stages from absolute pressures, target ratio per stage 3–4, max about 7.

5. Select compressor type: home/small reciprocating; public fast-fill HSR/recip; daughter high-suction hydraulic/booster; mother large balanced reciprocating.

6. Size dryer for inlet flow and worst-case water content; choose pre- or post-compression location by inlet pressure.

7. Size cascade: fast-fill public often needs large HP buffer; time-fill home can use small buffer.

8. Size electrical: motor kW by flow, inlet pressure, discharge pressure and cooling; VSD saves energy when demand varies.

9. Container size: home/small 10–20ft; standard 20ft; daughter with big storage 20–40ft; mother/multi-dispenser 40ft or multiple modules.

10. Safety scope: detection points, ESD zones, relief, ventilation, fire approvals, SCADA.

Rule-of-thumb capacity bands: home 50–300Nm³/h; medium public 300–1200Nm³/h; large standard 1200–1800Nm³/h; mother 2400–3600Nm³/h and above. Power varies widely; example small guides list home/light fleets lower single-digit tens of kW, medium stations higher, and large mother stations 55–800kW depending on flow and inlet pressure.

10. Energy and O&M Notes

• VFD/soft starter reduces start current and part-load waste; VFD especially useful for variable home/fleet demand.

• Priority sequencing reduces compressor run time by filling HP storage only when needed.

• Intercooling improves efficiency and lowers discharge temperature; aftercooler stabilizes storage dew point.

• Reciprocating wear parts—valves, rings, packing—need scheduled service; oil-free cylinders reduce oil carry but need valve/seal service. Example wear-part guidance in one group standard suggests oil-lubricated piston ring life around 8000h, with altitude >1000m special marking and vibration/leak limits per local standard.

• Hydraulic daughter stations have fewer rotating compressor parts but need hydraulic power unit, oil quality and pump seals.

• LNG/L-CNG O&M focuses on cryogenic pumps, vacuum integrity, vaporizer frost/ambient performance, boil-off and gas-detection calibration.

• Telematics: pressure per stage, discharge dew point, motor power, vibration, leak status, dispenser volume, alarm history.

11. FAQs

Can one container do CNG, LNG and petrol together?

Yes as separate systems. CNG needs compressor+cascade+dispenser; LNG needs tank+pump+vaporizer/dispenser; petrol needs petroleum tanks/dispensers. A hybrid station uses zoned layouts, separate containment, independent ESD and fire approvals. Do not share high-pressure CNG piping with cryogenic LNG piping.

Is a 50Nm³/h home CNG compressor enough?

For one personal CNG car with overnight time-fill, often yes. For multiple family vehicles or fast-fill, choose 150–300Nm³/h plus larger cascade. Inlet pressure matters: low pipeline inlet needs more motor power and more stages than trailer-fed buffer.

Do I need a dryer for home CNG?

If gas comes from a certified dry pipeline and meets vehicle standard, minimal filtration may suffice; if pipeline water dew point is uncertain or inlet pressure is low/ambient is cold, install dehydration before compression. For trailer gas from a proper mother station, verify dew point after pressure reduction.

What is the difference between container CNG compressor and LNG compressor?

CNG container uses gas compressor to 20–25MPa; LNG container uses cryogenic tank and pump, not high-pressure gas compression. If output must be CNG from LNG, use L-CNG high-pressure pump and vaporizer instead of a reciprocating CNG compressor.

How fast can a container CNG station be deployed?

Small skid/home units can be set on prepared pad and commissioned in days if power/gas/permits are ready. Public 20–40ft stations need factory integration plus site civil, electrical, gas tie-in, leak/purge tests and fire/explosion-protection approval; timeline depends on local code and customs/shipping, not only container build.

What pressure should the container compressor target?

Most standard CNG vehicle stations target about 25MPa final storage/dispensing unless local vehicle cylinders/nozzles use 20MPa or another approved class. Do not oversize to 30MPa+ unless vehicles, cylinders and authority approvals support it. L-CNG high-pressure pump/vaporizer output should be matched to the same CNG vehicle pressure class.

Is oil-free better for CNG?

Oil-free cylinder/lubricated-minimal designs reduce oil carryover into CNG, simplify filtering and improve vehicle/engine compatibility. They can cost more and may need more careful valve/seal service. Micro-oil designs with proper filtration are common in many stations; choice depends on vehicle standard, gas composition and maintenance policy.

Can a diesel engine drive the container CNG compressor?

Yes for off-grid or remote daughter/mother support, but most urban/home stations use electric motor for lower noise, simpler explosion protection and better VFD control. Diesel/gas-engine drive needs exhaust, ventilation and additional hazardous-area review.

What container size for a petrol-station CNG add-on?

A 20ft container can house a 400HP-class HSR compressor, dryer, cooler, cascade and controls for a medium fast-fill module. Add separate dispenser island space. If storage is large or L-CNG is included, use 40ft or multiple containers.

How to avoid confusion between "air compressor" and "CNG compressor"?

CNG/NG compressors handle flammable natural gas and require gas-rated, explosion-protected, dehydrated systems at high pressure. Instrument-air or pneumatic support in an LNG/CNG station is a separate oil-free/screw air package, usually low pressure about 0.6–0.8MPa, and must be isolated from fuel gas.

A container CNG/home/petrol/LNG project should first decide fuel output—CNG gas, LNG liquid or both—then select compressor or cryogenic pump accordingly. For CNG, size by Nm³/h at true inlet pressure and 20/25MPa vehicle class with dryer, cascade and ESD; for LNG/L-CNG, size by tank capacity, pump L/h, vaporizer Nm³/h and cryogenic safety rather than by "compressor HP" alone.