Frequently Asked Questions (FAQ) — Gas Mixing Systems, SNG, LPG & CO₂ Vaporizers

This FAQ page answers the most common questions about gas mixing systems, SNG production, LPG and CO₂ vaporizers, biomethane enrichment with propane, and nitrogen blending for calorific value adjustment. Furthermore, all answers are based on verified technical knowledge and GasGenix engineering experience from over 300 completed installations across Europe.

For definitions of key terms, visit our Gas Technology Glossary.

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1. SNG & Gas Mixing Systems — FAQ

What is SNG (Synthetic Natural Gas)?

SNG stands for Synthetic Natural Gas. It is produced on-site by blending LPG (propane or butane) with compressed air in a precisely controlled ratio. As a result, SNG achieves combustion parameters — particularly the Superior Wobbe Index (Ws) — equivalent to natural gas.

Furthermore, SNG is used as a direct substitute for natural gas in industrial burners, boilers, and gas appliances. Therefore, no burner modification or reconfiguration is required when switching from natural gas to SNG. This makes it the most practical gas backup solution available.

Source: EN ISO 6976:2016 

Where are gas mixing systems and SNG blenders used?

Gas mixing systems are used wherever a reliable gas supply is critical. Moreover, they serve industries where natural gas supply is unavailable, insufficient, or too costly to connect. Specifically, typical applications include:

• Glass factories and ceramic manufacturers.

• Power plants and cogeneration (CHP) units.

• Metallurgical and steel production facilities.

• Food and confectionery manufacturing plants.

• Gas distribution network operators — peakshaving and backup.

• Biomethane production plants — grid injection conditioning.

• Residential district heating complexes.

• Any industrial facility where building an NG pipeline is uneconomical or technically impossible.

Can SNG replace natural gas without changing burners?

Yes — this is the key advantage of a properly designed gas mixing system. SNG produced from LPG and air achieves a Wobbe Index equivalent to natural gas. Therefore, it is fully combustion-interchangeable. As a result, industrial burners, boilers, kilns, and furnaces operate on SNG without any modification, reconfiguration, or replacement. Furthermore, switchover from natural gas to SNG is automatic — without interrupting production.
How do I select the right SNG gas mixing system?

To select the appropriate gas mixing system, four parameters are needed:

1. Maximum flow rate of end-use appliances: Total installed power of all burners, boilers, or process appliances to be supplied with SNG — expressed in kW (total thermal input).

1. Required outlet gas pressure: P = ? bar (typically 1 to 10 bar).

1. Target Wobbe Index: e.g. Ws = 45.5 – 54.7 MJ/Nm³ for H-gas specification — or alternatively, the heating value of the reference gas (natural gas).

1. LPG composition: e.g. 95% propane + 5% butane, or bioLPG.

Additionally, ambient operating temperature and installation location (indoor / outdoor / containerised) affect equipment selection. Therefore, contact GasGenix with these parameters for a customised system offer and OPEX analysis.

What is the difference between an automatic SNG blender and a Venturi mixer?

An automatic SNG blender  uses precision flow control valves, mass flow meters and a PID control system to maintain the exact LPG-to-air ratio. As a result, it delivers ±1.00% mixing accuracy and a stable Wobbe Index regardless of flow variations and LPG composition. Capacity: 100 to 10,000 Nm³/h.
A Venturi mixer uses the Venturi effect to draw air through the LPG stream without active control. However, mixing precision is lower — particularly at variable flow rates. Furthermore, maximum outlet pressure is limited to approximately 0.5 bar. Therefore, Venturi mixers are suitable for simple, smaller-scale applications with stable flow rates.

Is propane (LPG) more calorific than natural gas?

Yes. Technical propane (C₃H₈) has a gross calorific value of approximately 100.5 MJ/Nm³ — compared to 39–41 MJ/Nm³ for natural gas (H-gas group E). Therefore, propane is approximately 2.5 times more calorific than natural gas per unit volume.
Additionally, propane has a consistent, stable calorific value — unlike natural gas, which can vary by supplier and season. As a result, SNG produced from propane and air delivers a stable, predictable energy output to industrial processes.

What are the costs of operating an SNG gas mixing system?

The main operating cost of an SNG system is the price of LPG fuel. Furthermore, equipment operating costs — including LPG vaporization energy, compressor electricity, and maintenance — amount to approximately 2–3% of the LPG wholesale price.
GasGenix provides a comprehensive OPEX and energy performance analysis for each project. This analysis quantifies the total cost of ownership and the financial benefits compared to natural gas supply. Moreover, during periods of high natural gas prices, SNG can be significantly more cost-effective.

Do I need special permits to install an SNG backup system?

Generally, no special permits are required from the natural gas supplier. This is because the SNG system connects after the natural gas metering node — not to the public gas network itself.
However, local regulations apply to the installation of LPG storage tanks, vaporizers, and pressure equipment. Furthermore, all GasGenix gas mixing systems comply with EN ATEX and PED directives, and are supplied with CE certification and UDT/TÜV documentation as required. Installation typically takes approximately 2–4 weeks.

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2. Biomethane Enrichment with Propane (LPG) — FAQ

Why does biomethane need to be enriched with propane before grid injection?

Raw biomethane from biogas upgrading typically has a gross calorific value of 35–38 MJ/Nm³. However, maintaining a minimum calorific value is a standard requirement of gas distribution network operators. Furthermore, the natural gas grid specification (H-gas) requires a gross calorific value of at least 39–42 MJ/Nm³ at the grid injection point.
Additionally, EN 16723:2017 requires online monitoring of the heating value and Wobbe Index (Ws) every 30 minutes before biomethane injection into the natural gas network. Therefore, biomethane that does not meet these minimum thresholds must be conditioned before injection.
The standard conditioning method is propane (LPG) enrichment — typically injecting 2–10% LPG into the biomethane stream. As a result, the blended gas meets the grid operator’s calorific value and Wobbe Index requirements. Furthermore, the enriched biomethane can be injected into the distribution network without risk of appliance malfunction or burner instability.

What is the Biomethane Enrichment Mixing System?

The GasGenix Biomethane Enrichment Mixer is a precision gas mixing system for conditioning raw biomethane with propane (LPG). Moreover, it includes real-time Wobbe Index and calorific value monitoring, automated PID control, and ATEX-compliant instrumentation.

Key technical specifications:

• Mixing capacity: 10,000 Nm³/h (scalable from 100 to 10,000 Nm³/h).

• Design pressure: 16 bar.

• Outlet gas pressure: up to 10 bar.

• Design temperature: −25°C to +60°C.

• Electrical power: 2.4 kW / 240V.

• Certification: CE  | Compliance: EN ATEX, PED.

• Supported LPG: propane, bioLPG.

Can bioLPG be used instead of fossil propane for biomethane enrichment?

Yes. bioLPG is chemically identical to fossil propane in composition and combustion properties. Therefore, no system modifications are required when switching from fossil LPG to bioLPG as the enrichment agent.
Furthermore, using bioLPG as the corrective gas enables a fully renewable gas output — biomethane enriched with bioLPG. This configuration is compliant with EU RED III Directive 2023/2413 and eligible for Guarantees of Origin (GOs). Additionally, it supports EU ETS, CBAM, and ESG/CSRD-ESRS reporting requirements for industrial decarbonisation programmes.

In which countries is biomethane-LPG enrichment most commonly used?

Biomethane enrichment with LPG is most widely implemented in Germany and the Czech Republic, where strict grid injection standards and high biomethane production volumes make calorific value conditioning a standard requirement.
Furthermore, the technology is growing rapidly across Poland, the Netherlands, France, and Scandinavia — driven by increasing biomethane grid injection capacity and EU renewable gas targets. GasGenix supplies enrichment systems across European markets.
Source: European Biogas Association (EBA).

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3. Calorific Value Adjustment with Nitrogen — FAQ

Why would you add nitrogen to reduce the calorific value of gas?

Some industrial processes and end-use appliances are calibrated for lower-calorific gas (L-gas specification). Moreover, certain gas network operators supply L-gas with a calorific value of approximately 22–30 MJ/Nm³ — significantly lower than H-gas (39–42 MJ/Nm³).
Therefore, where a facility receives H-gas but requires L-gas quality — for example, when replacing an existing L-gas supply — nitrogen blending reduces the calorific value to the required level. Furthermore, nitrogen is inert, non-combustible, and widely available as an industrial gas, making it a safe and practical corrective agent.

How does a biomethane-nitrogen blending system work?

The system doses a controlled stream of nitrogen (N₂) into the biomethane or natural gas supply. Specifically, the blending ratio is calculated to achieve the target calorific value. As a result, the outlet gas meets the L-gas specification required by the process or appliances. Furthermore, the GasGenix nitrogen blending system includes real-time gas quality measurement and automated control. Therefore, the target calorific value is maintained continuously — regardless of variations in the upstream gas composition.

Does nitrogen blending affect gas combustion safety?

Nitrogen is an inert, non-combustible gas. Therefore, it does not create any explosion or combustion risk when blended into a gas stream. However, the blended gas must still meet all applicable gas quality standards — particularly for Wobbe Index and calorific value — before use in end-user appliances. Furthermore, all GasGenix nitrogen blending systems are designed to prevent overdosing. Specifically, they include safety interlocks that stop nitrogen injection if the outlet gas quality falls outside the permitted specification range. As a result, downstream appliances are protected from receiving off-specification gas.

What industrial applications use nitrogen blending for calorific value reduction?

Nitrogen blending for calorific value reduction is applied in several specific industrial situations. These include:

• Facilities transitioning from L-gas to H-gas networks — where appliances are calibrated for L-gas.

• Industrial processes requiring low-calorific gas for precise heat input control.

• Gas turbines and engines with specific fuel gas quality requirements.

• Research and testing facilities requiring variable calorific value gas streams.

Additionally, nitrogen blending can be combined with propane enrichment to achieve precise intermediate calorific values — providing full flexibility in gas quality management. Contact GasGenix for a detailed engineering assessment of your specific requirements.

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4. CO₂ Vaporization Systems — FAQ

What is a CO₂ vaporization system?

A CO₂ vaporization system converts liquid carbon dioxide (LCO₂) stored in a cryogenic tank into gaseous CO₂ for industrial process use. GasGenix systems use water bath vaporizers — a proven, energy-efficient technology. Specifically, heated water transfers thermal energy to the liquid CO₂, converting it to gas through a closed heating circuit powered by a gas-fired boiler (LPG or natural gas).
Furthermore, the system includes a pressure safety mechanism preventing dry ice formation below the CO₂ triple point: 5.18 bar / −78.5°C. Therefore, the system operates safely even in severe winter conditions — at ambient temperatures as low as −20°C.

What is dry ice and why is it dangerous in CO₂ systems?

Dry ice is solid CO₂ that forms when liquid CO₂ pressure drops below the triple point (5.18 bar, −78.5°C). At this point, CO₂ solidifies directly without passing through the liquid phase — a process called solidification. In a CO₂ supply system, dry ice formation is dangerous because it blocks valves, pipelines, and vaporizer elements. Additionally, when dry ice sublimes in a closed space, pressure increases rapidly — creating a serious risk of equipment damage. Therefore, GasGenix CO₂ vaporizers include an integrated pressure safety system that continuously monitors and maintains pressure above the triple point.