2m³ Liquid gas Cryogenic Mini Tank

| Product Overview

The Mini Tank 2m³ is the lighter, more flexible variant, spanning an effective volume range of 1500–2500 L with tare weights from 1207 kg to 1900 kg depending on the selected capacity and working-pressure tier (1.6 / 2.2 / 2.4 MPa). It is engineered as a straightforward liquid storage and low-pressure delivery system: the inner vessel (022Cr19Ni10 / S30408 stainless steel) is suspended inside a carbon steel or stainless outer jacket and insulated by a multi-layer wound vacuum-perlite composite—the same super-insulation technology used in the manufacturer's larger 5–50m³ vertical storage tanks but scaled to a 2m³ envelope. The Mini Tank 2m³'s defining market feature is its onboard electronic scale (first-to-market in China for this tank class): instead of a differential-pressure liquid level gauge that requires temperature compensation and periodic recalibration, the entire tank sits on load cells that directly measure the remaining liquid mass. This allows the end-user to perform a "估检" (visual estimate inspection)—reading the actual kilograms of liquid remaining without requiring the delivery truck to weigh-in at a weighbridge. The Mini Tank 2m³ also supports an IoT remote liquid level telemetry system, enabling the gas supplier to monitor tank levels remotely and schedule refill deliveries proactively rather than reactively. Its multi-capacity architecture (1500–2500 L) lets a single platform footprint serve customers with modestly different consumption profiles without re-engineering the installation.

The Micro Tank 2m³ is the heavy-duty, self-contained evolution of the platform. It carries an effective volume of 1.9 m³ on a φ1300 × 2185 mm inner cylinder, with tare weights rising from 1500 kg (1.6 MPa) to 2021 kg (3.4 MPa). The critical difference is that the Micro Tank is not just a storage vessel—it is a complete functional station. Each unit ships with a 60 Nm³/h ambient-air cascade vaporizer and a pressure-building circuit as standard equipment. The vaporizer is a finned aluminum heat exchanger that converts liquid cryogen to ambient-temperature gas using atmospheric heat alone—zero electrical power, zero moving parts. The pressure-building circuit is a small self-contained loop that draws liquid from the tank bottom, vaporizes it in a small PB coil, and returns the gas to the tank headspace to maintain delivery pressure as liquid is withdrawn. These subsystems transform the Micro Tank 2m³ from a passive storage container into an autonomous gas supply station: connect a downstream pressure regulator and flow meter, and the system delivers continuous gaseous product without external pumps, external heaters, or operator intervention.

The three pressure tiers across the Micro Tank 2m³—1.6 MPa, 2.5 MPa, and 3.4 MPa working pressure—correspond to different end-use pressure requirements. The 1.6 MPa tier is the general-purpose industrial grade (laser cutting, welding shield gas, laboratory central supply). The 2.5 MPa tier accommodates medium-pressure distribution networks where gas must travel through extended pipe runs with non-trivial line loss. The 3.4 MPa tier serves high-pressure applications such as LNG vehicle refueling buffer storage, high-pressure cylinder filling manifolds, and processes requiring elevated delivery pressure without a downstream compressor.

Safety architecture is dual-redundant on the inner vessel: a spring-loaded safety relief valve (set at approximately 106% of design pressure, specific to each pressure tier) provides the primary overpressure protection with automatic reseating capability, while a rupture disc serves as the non-reclosing secondary defense. The outer jacket carries its own vacuum safety valve at 0.18 MPa—a low-pressure device that protects the jacket from positive pressure in the unlikely event of an inner-vessel leak into the annulus, while also serving as the vacuum pump-out port during initial evacuation and periodic vacuum maintenance.

Media compatibility spans the full industrial gas spectrum: LOX (liquid oxygen), LIN (liquid nitrogen), LAr (liquid argon), LCO₂ (liquid carbon dioxide), and LNG (liquefied natural gas, 3.4 MPa tier for the Micro Tank). The inner vessel material—022Cr19Ni10 (S30408)—is the Chinese standard equivalent of AISI 304L, selected for its combination of deep-cryogenic toughness (Charpy V-notch > 27J at −196°C), weldability without post-weld heat treatment, and universal chemical compatibility with the target media. The S32168 (06Cr18Ni11Nb, a niobium-stabilized 304 equivalent) variant is offered for LNG service where the risk of sensitization from repeated thermal cycling is higher.

| Working Principle

A 2m³ cryogenic liquid storage tank is a double-walled, vacuum-insulated pressure vessel whose function is to store a cryogenic liquefied gas at its boiling point (typically −183°C for LOX, −196°C for LIN, −186°C for LAr, −162°C for LNG) and deliver it either as liquid (for transfer to another vessel) or as ambient-temperature gas (for process consumption).

Insulation and the Zero-Boil-Off Illusion:

The tank does not maintain temperature actively—there is no refrigeration system. Instead, it relies on passive super-insulation to minimize heat ingress from the ambient environment. The insulation system is a three-layer composite: (1) the annular vacuum space between the inner and outer vessels, evacuated to ~10⁻³ Pa or lower, eliminating convective and conductive gas-phase heat transfer; (2) multiple layers of reflective foil (typically aluminum-coated Mylar) wound around the inner vessel, reducing radiative heat transfer—each additional layer reflects ~95% of the incident thermal radiation; and (3) perlite powder (expanded volcanic glass) filling the remaining annulus volume, providing a microporous barrier that suppresses residual gas conduction and acts as a secondary radiation shield. The combined effective thermal conductivity of this composite is on the order of 1 × 10⁻⁴ W/m·K—roughly 10,000× lower than solid stainless steel.

Despite this insulation, heat ingress is never zero. The larger 2m³ envelope presents a greater wetted surface area than its 1m³ counterpart, and the total continuous heat ingress scales accordingly. For a 2m³ tank with vacuum-perlite insulation, a typical heat leak of 1–2 W/m² still translates to a daily static boil-off on the order of 0.5–1.0% of tank volume under no-withdrawal conditions. The boil-off gas accumulates in the headspace, raising the tank pressure. When the pressure reaches the pressure-building regulator set point (for tanks equipped with the PB circuit), or ultimately the safety valve set point, the excess pressure is vented.

The Gas Delivery Cycle — Micro Tank Variant:

The Micro Tank 2m³ operates as a complete liquid-to-gas conversion station through three interacting circuits:

 Liquid withdrawal circuit: When the downstream gas-use valve opens, the tank's headspace pressure forces liquid through the bottom liquid outlet, up the internal withdrawal tube, and into the ambient-air vaporizer. The vaporizer is an array of vertically oriented finned aluminum tubes connected in series—the liquid enters at the bottom, progressively warms and vaporizes as it rises, and exits at the top as ambient-temperature gas. The energy for this phase change comes entirely from natural convection of ambient air over the fins; no external heat source is involved. The 60 Nm³/h specification means the vaporizer is sized to deliver 60 normal cubic meters of gas per hour continuously under rated ambient conditions (typically 20°C, 60% RH)—a 50% uplift over the 40 Nm³/h unit supplied with the 1m³ Micro Tank, matching the 2m³ platform's larger storage volume and sustained delivery duty.

Pressure-building circuit:  As liquid is withdrawn, the tank pressure would drop if uncompensated—the headspace volume increases but the mass of gas in the headspace does not. The PB circuit counters this: a small bleed of liquid is drawn from the tank bottom, passed through the PB coil (a smaller finned heat exchanger), vaporized, and returned to the tank headspace as pressurized gas. A pressure-building regulator controls this loop, opening when headspace pressure falls below the set point and closing when pressure is restored. This maintains a stable delivery pressure throughout the entire withdrawal cycle, from full tank to near-empty.

Safety relief circuit: The inner vessel carries two overpressure protection devices in series-parallel logic. The spring-loaded safety valve is the primary—it opens on overpressure, vents until pressure falls to its 85%+ reseat point, and closes automatically. The rupture disc is the secondary—a non-reclosing, frangible metal diaphragm that bursts at a specific differential pressure and provides a definitive, cannot-fail-to-open last-resort defense. The outer jacket carries its own vacuum safety valve at 0.18 MPa to protect against an inner-vessel leak into the annular space.

The Electronic Scale Advantage — Mini Tank Variant:

Traditional cryogenic tanks use differential-pressure (DP) level gauges: a high-pressure tap at the tank bottom, a low-pressure tap at the headspace, and a DP transmitter that converts the hydrostatic head ρ·g·h to a level reading. This works adequately when the liquid density ρ is known, but cryogenic liquid density varies with saturation pressure, temperature stratification, and media type—a 10% density error yields a 10% level error. The Mini Tank 2m³'s electronic scale bypasses this: by measuring the total tank mass and subtracting the known tare weight (1207–1900 kg depending on the selected capacity and pressure tier), the remaining liquid mass is known directly. For liquid nitrogen at 808 kg/m³ saturation density, a 2000L nominal tank containing 1400 kg of liquid is at approximately 87% fill—and this number is trustworthy regardless of the liquid's thermodynamic state. This mass-based readout is particularly valuable across the Mini Tank 2m³'s multi-capacity range, where a single scale platform must correctly report fill across different configured volumes.