How does it work?
The process of the GasReformer is based on steam reforming, but is here done somewhat differently. “The goal is to produce as much methane in the process as possible. This application is entirely new,” Jansson said. All heavier
hydrocarbons, and also the methane, are cracked to an intermediate product which is hydrogen and carbon monox-ide. Into the catalyst is fed the gas and steam. Through a reaction in the catalyst process, which is a function of tempera-ture, pressure, and the amount of steam injected, gas is achieved which consists of 80% or more methane, less than 11%
hydrogen and some 10% or less carbon dioxide. “In the process, almost regard-less of the composition of the input gas, this is the resulting composition,” he notes. The catalyst is a pressure vessel with pellets of reduced nickel.
In the process, the associated gas pass-es through a de-sulphurization reactor and is injected into the Reformer. The output gas is then fed into the engine.
The engine controls the gas fl ow auto-matically and steam produced by the ex-haust gas boiler of the engine is fed into the process based on need. The reactions of the process are very fast. “There are other technologies which fi ltrate the heavier hydrocarbons from the gas, but you then have to get rid of these sepa-rately,” Jansson said.
OFFSHORE
Making Flare Gas Useful
Wärtsilä has developed the GasReformer, a product which converts associated gas, which is of-ten fl ared, into usable fuel for its dual-fuel engines. Henrik Segercrantz reports.
Fig. 1
Example of the GasReformer performance in a real case.
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Jansson shows a real-case example (Fig. 1, previous page) where the inlet gas composition has the methane num-ber 56 as it includes heavier hydrocar-bons although as much as 78% methane.
After the GasReformer, the composition is 79% methane, 10% hydrogen, 10%
carbon dioxide but there are no heavier hydrocarbons. The methane number has increased to 98.
Wärtsilä started developing the Gas-Reformer seven years ago. A prototype of the Gas Reformer was built, as a proof of concept.
“It could, for example, turn 100% pro-pane into methane,” Jansson said. The product was then industrialized, which included the entire process of adding safety systems, etc., and the classifi ca-tion and approvals. In December 2012 the fi rst GasReformer unit was deliv-ered, after successful factory acceptance tests at Wärtsilä’s factory in Finland. The GasReformer is classifi ed to the Off-shore regulations by Det Norske Veritas.
The platform will receive four 8-cylin-der Wärtsilä 34 in-line diesel-generators, two of which will run on crude oil and two DF dual-fuel engines running on both crude oil and on gas as fuel. Flaring was not allowed by the authorities. “We have a diffi cult gas, a diffi cult crude oil, but Wärtsilä could provide the solution.”
The pellets in the reactor of the GasRe-former have to be renewed every three to four years. This is done through re-placing the entire reactor pressure vessel with a unit served ashore. Wärtsilä han-dles this process as part of the contract with the client. The GasReformer has two desulphurizer reactors, with one as backup. The lifetime of one unit, using
zinc-oxide as adsorbent, is approximate-ly one year of continuous operation. The units are replaced when needed.
The fi rst produced GasReformer is a 8MW unit.
It needs a total of 1,775kg steam per hour. Of this amount 375kg fresh water is consumed per hour, in the reformed gas. 1,400kg is recycled into the process.
The amount of fresh water needed in the process is a function of the methane number of the inlet gas.
In addition some cooling water is needed, hydrogen for start-ups and blow-downs or fl ushing, when needed, plus some electricity for operation, start-ups and when in stand-by (Fig. 2, next page).
With the GasReformer in the product portfolio Wärtsilä is capable of provid-ing an extensive system for handlprovid-ing associated gas for the oil industry. It can supply the entire power production technology and through the aquisition of Hamworthy, also inert gas systems, and systems for fl are gas recovery and fl are gas ignition.
Artists impression of the GasReformer
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Maritime Reporter & Engineering News • APRIL 2013OFFSHORE
Potential also for VOC recovery and in shale gas operations
VOC, or Volatile Organic Compounds, re-covered in the process of crude oil handling provides another potential use of the GasRe-former. In crude oil pumping and handling, the crude oil is heated to improve its viscos-ity. When heating, the lighter hydrocarbon fractions of the crude evaporate. These vol-atile organic compounds (VOCs) are tradi-tionally vented into the atmosphere. “Now, VOCs can also be utilized by combining a VOC Recovery System with Wärtsilä Gas-Reformer and dual-fuel engines,” Jansson said. Through Hamworthy, Wärtsilä also provides VOC Recovery Systems. Jansson presented some calculations to Maritime Reporter where a Floating Storage Unit could receive all of the fuel needed for powering the cargo pumps from VOC gas, by installing a system onboard com-bining these two technologies.
“There are many potential application for the GasReformer also in land-based appli-cations. So far we have concentrated on the offshore oil industry,” Jansson said.
“A wider use of Liquefi ed Petroleum Gas, which is propane or butane, as fuel is now also possible. Another potential sec-tor could be in shale gas recovery, where a power plant is easily set up using the Gas-Reformer.”
The GasReformer is not suitable to be used for bio-gases nor gases with high amounts of sulfur, above 40ppm. Nor does it suit for processing gases with high amount of inert gases, nitrogen or carbon dioxide nor for gases including so called olefi ns. Wärtsilä’s GasReformer is a completely new product, now ready for the market. The size of a GasReformer for an engine shaft power of 8MW is designed to be 5.3m long, 3m wide and 3.3m high. The weight of the unit is ap-proximately 17 tons.
Fig. 2: Consumables of an 8MW GasReformer Unit
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