Mapro’s Sliding Vane Rotary Compressors: The Perfect Solution for Gas Injection Systems in Anaerobic Digesters

MAPRO® International S.p.A. is a manufacturing company established in 1959, specialized in the conveyance of many gaseous fluids like Butane, Methane, Propane, Ethylene, Butadiene, Hydrogen, Carbon Dioxide, Natural gas, with a specific experience in the biogas industry.

In addition to standard configuration products, MAPRO® designs and manufactures gas blowers and compressors according to customer’s specifications, all our units comply with Directive 2014/34/EU (ATEX).

SLIDING VANE ROTARY COMPRESSORS FOR BIOGAS

MAPRO® sliding vane rotary compressors are widely used for mixing the sludges in anaerobic digesters and for the so-called “gas injection system” where the gas is conveyed from the digester dome and reinjected at the bottom of the digester, thus providing uniform conditions of the organic material inside it.

Anaerobic digestion is a biological process where microorganisms breakdown biodegradable materials in absence of oxygen. It takes place into anaerobic digesters where the process produces biogas mainly consisting of methane and carbon dioxide.

Typical Biogas Compressors for Gas Injection Systems

MAPRO® BACKGROUND IN SLIDING VANE ROTARY COMPRESSORS FOR GAS INJECTION SYSTEMS

As of now MAPRO® has installed about 3500 biogas sliding vane rotary compressors, currently working on gas injections systems around the world.

Among them, MAPRO® boasts # 26 R 160 G – 132 kW/177 HP sliding vane rotary compressors installed in what is today’s world biggest anaerobic plant at Gabal El Asfar (Cairo Egitto).

MAPRO® is also currently supplying sliding vane rotary compressors to the “Acheres anaerobic plant”, in Paris, France (see picture attached), which currently the biggest WWTP in Europe, undergoing an upgrade that will turn it into the world’s biggest by 2024.

Over the past 20 years Mapro has installed 56 compressors that are currently working at the Acheres site and in 2021, we have started to ship part of the additional 25 Mapro rotary vane compressors selected to handle the biogas section of the new plant portion under construction: #15 R180 – 250 kW/335 Hp motor Rotary Vane Compressors to inject 2000Nm3/h @ 3.5 Barg in mixing gas digesters application, plus another 10 R300 – 95 kW/127 Hp motor Rotary Vane Compressor used in the biogas storage process.

GAS INJECTION SYSTEMS ADVANTAGES

Why more and more customers prefer MAPRO technology instead of anaerobic digester mixing system?

A response comes from the “Ca’ Foscari University of Venice”, a European excellence in studying anaerobic digestion systems. They carried out a technical comparison between gas injection and mechanical mixing systems that clearly show the advantages of the mixing over the mechanical system.

Main advantages can be summarized as follows:

• No sedimentation thanks to gas bubbling from the bottom due to the mixing
• High production of gas thanks to a complete and uniform mixing and to a low temperature gradient in the sludge
• Low power consumption (up to 50% energy saving): no friction between sludge and mechanical parts
• High reliability: no corrosion and no struvite
• Easy and low cost maintenance: no moving parts inside the sludge

Mixing digester biomass using a rotary vane compressor will deliver a more uniform distribution of flow into blind areas a propeller doesn’t reach, with a resulting lower energy consumption, lower maintenance, higher reliability, lower corrosion and better system efficiency

If you are interested in knowing all the details, you can download the University of Venice study here.