Biomethane propane conditioning system

Biomethane conditioning with propane involves the precise dosing of commercial propane (or LPG) into the biomethane stream in the gas phase. This method, referred to as propanization or biomethane enrichment, aims to increase the gross calorific value and the Wobbe index of the biomethane to the values required by the gas network operator.

I-Maximum supplies a fully configured propanation system — from LPG tanks to the measurement and analytical system — integrated with the MGA-BIO mixer. Each system component is selected and configured taking into account the specific nature of working with propane (LPG) and the safety requirements of a biomethane installation

The energy analysis of the biomethane conditioning method using propane is based on the energy balance and a precise calculation method developed by MSc Eng. Świętosław Kariuk (example provided below).

The design of the MGA-BIO mixer takes into account all key physicochemical properties of propane that directly affect the correct operation of the propanization system:

• Condensation temperature of technical propane: at a pressure close to atmospheric (~1 bar), it is approximately –42°C; as pressure increases, the condensation temperature rises (e.g., at a pressure of approx. 11 bar, it is approximately 21°C) — the mixer ensures that the gas temperature is maintained above the saturation temperature corresponding to the current operating pressure.

• Energy parameters of technical propane — key parameters for the energy balance algorithm and dosing control.

• Propane condensation in pipelines — the mixer is equipped with a liquid phase detection sensor and a condensate separator, enabling controlled accumulation and drainage of condensate without stopping the system.

• Impact of pressure on physical properties — redundant pressure and temperature sensors on the LPG line; design taking into account gas-liquid phase equilibrium (P–T) diagrams and a temperature margin relative to the saturation point at the current operating pressure.

• Share of correcting gas: dosing of technical propane at a level of 3–7% by volume enables effective compensation of biomethane calorific value and fulfillment of quality requirements at the network entry point.

The MGA-BIO Mixer is a modern, fully automatic device equipped with an advanced control system that ensures precise and reliable biomethane conditioning. The control system includes the following functions:

• Remote control and monitoring — the ability to remotely monitor and adjust the operation of the MGA-BIO mixer: pressure, flow rate, and the heat of combustion of biomethane.

• Control of the heat of combustion of biomethane and LPG streams — precise mixing of LPG and biomethane is achieved through continuous analysis of the heat of combustion of both streams. This is performed directly on the mixer skid without the use of a chromatograph, which allows for the immediate adjustment of the mixture composition to the specified parameters—even in the case of fluctuating heat of combustion of biomethane or propane.

• Pressure control — full control of the operating (mixing) pressure at every stage of the conditioning process.

• GAS detection and signaling — emergency shutdown of the MGA-BIO Mixer in the event of gas leaks, along with the activation of visual and audible alarms.

• Liquid phase detection — additional monitoring of the biomethane and LPG mixture temperature using a temperature sensor, preventing the ingress of liquid phase LPG in emergency situations.

I-Maximum offers solutions mounted on a frame (skid) or in a containerized enclosure, where LPG vaporizers and gas mixers form a compact technological system. Skid-mounted or containerized solutions provide:

• A ready-to-operate system — plug & play

• Full ATEX and PED safety compliance

• Fast installation capability at the biomethane plant site

• Integration with the SCADA system of the biomethane plant

• Compact dimensions tailored to the site installation conditions