Indirect fluidized bed gasification of waste. Gasification of biomass and waste opens the full potential of this valuable carbon source. Combustion is still used more nowadays, but gasification and specifically MILENA has more potential. MILENA is an indirect gasifier, meaning that the product gas is not being diluted with N2(from combustion air) and CO2 and H2O (combustion products).
Gasification of biomass or waste.
Solid biomass or waste enters the MILENA in a central riser. A small amount of steam or air is also injected in the riser to fluidize hot bed material. Using the energy of the hot bed material, the biomass or waste reacts into three basic products being solid (char), condensable (tars) and product gas (mainly H2, CO, CH4, C2H4, CO2, and H2O).
Utilization of residues as energy source.
The product gas, char and tars flow upwards into a settling chamber where most of the char together with bed material is separated from the product gas. Remaining char and tars are recovered in downstream gas cleaning, before being send to the combustion chamber positioned around the riser. In this chamber char and tars are combusted, heating up the bed material before it flows to the riser completing the cycle.
Cooling of produced gases.
As of the two reaction zones, the MILENA produces a valuable product gas as well as a flue gas. While the gases both need to be cooled and cleaned, separate cooling allows for optimization of efficiency as well as availability. The product gas is cooled by means of saturated or superheated steam generated in the flue gas cooler, avoiding the presence of cold spots and fouling by tars in the product gas cooler.
Features and benefits.
In MILENA the use of a separate combustion zone providing the heat for the pyrolysis results in 100% carbon conversion, boosting gasifier efficiency and minimizing ash volume. The efficiency is further increased as tars and char removed from the product gas are recycled to the MILENA’s combustor reactor where the energy is used for the gasification process.
MILENA delivers product gas with minimal dilution, while using ambient air as oxygen supplier for the combustion reactor. Pure oxygen supply by an ASU is unnecessary.
The undiluted product gas has a high energy density, typically 17 to 24 MJ/Nm3 (430 to 620 Btu/scf) depending on the gasified material, typically twice the energy density of syngas and three to four times the energy density of conventional gasification. This product gas can be applied in gas engines and gas turbines. For the latter a high energy density is required. The undiluted product gas is also a good basis for downstream conversion to liquid and gaseous fuels.
The OLGA tar removal system is based on a conventional multi-stage scrubber in which special scrubbing oil is used to clean gases from tars. These gases can originate from biomass and waste gasification, as well as coke ovens or underground coal gasification.
Removal of fines and aerosols.
Fine particles and aerosols are removed by the 1st loop as well by means of a downstream electrostatic precipitator (ESP). This ESP cleans itself by the tar/oil fraction it captures. The condensed tars and captured solid particles is recycled to the gasifier. The combination of oil scrubbing and ESP improves the removal efficiency as also very small fines enclosed by oil are captured.
Condensation of heavy tars.
In the 1st loop of OLGA, the gas is gently cooled down by scrubbing oil. Heavy tar particles condense and are collected, after which they are separated from the scrubbing oil and recycled to the gasifier to recover the associated energy content of the tars. The condensation occurs above the water dewpoint of the gas, avoiding the production of contaminated waste water.
Absorption of light tars.
In the 2nd loop, lighter tars are absorbed by scrubbing oil lowering the tar dewpoint to 20°C or even less. In the absorber column the oil is saturated by these tars. This saturated oil is regenerated in a stripper. Hot air or steam is used to strip the tar out of the scrubbing oil. Again, tars can be recycled to the gasifier where they are destructed and contribute to the energy efficiency.
Features and benefits.
With the use of OLGA, product gases no longer suffer from tar related problems and can be dewatered, further cleaned if necessary and utilized. Because all captured solids, heavy and light tars are recycled, OLGA is in principle a waste free system. With the special scrubbing oil being re-generated, OLGA has a clear operational benefit compared to conventional biodiesel or rapeseed oil (RME) scrubbing systems.
OLGA only captures tars it does not change the product gas composition. As such, OLGA enables MILENA to produce a lot of methane, the secret of success in the record high efficiency from biomass to renewable natural gas OLGA enables MILENA to be as efficient as possible, tar reducing measures in the gasifier, which reduce efficiency and energy density are not necessary. OLGA removes tar at a typical 1% parasitic energy consumption. With the captured tars containing a considerable amount of energy, recycling the tars ensures that this is not wasted but kept in the system and contributing to the energy output of the plant.
Small CHP (#applications; #power, #CHP):
Modular gasification solution for combined heat and power. Synova Technology supplies a standard, fully modularized MILENA system named SMM. The SMM system combines the MILENA and OLGA technologies with downstream water condensation and scrubbing to deliver clean product gas on specification for reciprocating gas engines.
Basis of the SMM delivery is a detailed design that is based on easy-to-transport modules, sized as 30’ and 40’ containers. The modules are completed and tested as far as practically possible in the workshop. On site the plant is quickly assembled hoisting the modules in place and connecting the modules. The pre-defined design and the modular construction make this concept an excellent solution for facilities with a small capacity in remote locations.
The MILENA-OLGA technology is very fuel flexible. A variety of biomasses and waste feedstocks can be used to fuel the gasifier. As the SMM is a standard design, built up out of pre-defined modules, the installed capacity of the SMM is depending on the fuel quality. The SMM can handle 900 to 1400 kg/hr fuel with an energy value of 4 to 6 MW. The system can deliver 3.0 to 4.5 MW (10 to 15 MM Btu/hr) clean product gas to reciprocating gas engines, with which the net electricity supply of this facility will be between 1.0 and 1.5 MW.
Features and benefits.
A fuel flexible power station, converting locally available biomass and waste with high efficiencies. A pre-designed concept, minimizing the delivery time and simplifying transport as well as on-site construction work, making advanced technology feasible for small scale and remote locations.
The optional zero-water-discharge system purifies and recycles the facilities waste water, minimizing water demand and eliminating a waste water stream. Producing undiluted product gas, the SMM is also an attractive basis for demonstration facilities that are aiming to produce fuels and chemicals in downstream catalytic and biological processes.
MILENA-OLGA basis at intermediate capacity
Synova Technology supplies stick-built MILENA-OLGA facilities. Fueled by biomass and/or waste, these facilities deliver clean product gas which is on specification for a gas turbine combined cycle powerplant.
Clean product gas for production of fuels and chemicals
MILENA can be fluidized by steam or CO2 instead of air, which will eliminate the N2 dilution of the product gas. The resulting gas volume is composed out of mainly H2, CO, CO2 and CH4. However, on an energy basis the syngas components (H2 and CO) contain only 15% to 25% of the total energy. Methane, ethylene and BTX (benzene, toluene, xylene) are the components that together contain most of the energy in the product gas. In future plants the collection and sale of BTX and ethylene as valuable base chemicals is a logical step. The collection of BTX using OLGA technology is already available today.
Clean product gas as a renewable alternative for natural gas
Next to fueling gas-turbines, the gas produced by MILENA-OLGA is also applied as a renewable alternative for natural gas in industry. The cleanliness of the gas make transport to various consumers such as kilns, boilers and engines possible.
Tailored to fit Caterpillar-Solar Turbines
Our stick-built facilities are designed to meet Caterpillar-Solar’s Taurus and Titan gas turbines. The M30, a MILENA-OLGA facility with a maximal fuel inlet capacity of 30 MW (100 MM Btu/hr) is a perfect match to the Taurus range gas-turbines. The high energy density of the product gas, typically 17 MJ/Nm3 (430 Btu/scf) with wood chips as fuel and 24 MJ/Nm3 (620 Btu/scf) with waste (RDF) reduces the compression rate before the turbine ensuring a high overall net efficiency.
Production of high quality syngas
MILENA-OLGA product gas us undiluted. As such it can be converted with minimal energy consumption to various syngas qualities (mixtures of CO and H2 or CO, CO2 and H2) to match downstream catalytic or biological conversion to various fuels and chemicals such as Fischer Tropsch diesel and methanol.
Production of Renewable Natural Gas at record efficiencies
MILENA-OLGA product gas as a basis of the production of methane or renewable natural gas (RNG) results in record high efficiencies, thanks to the high initial methane content of MILENA gas and the fact that OLGA removes tars without touching this methane. An overall efficiency of 70% (LHVRNG/LHVwood) is possible.