Petrochemical - Synthetic Gas

Nickel

Catalyst used in steam methane reforming

CoMo / NiMo catalyst bed

Catalyst used to convert sulfur to hydrogen sulfide, H2S

Steam methane reforming Autothermal reforming Partial oxidation of methane or hydrocarbons Catalytic version of partial oxidation

Technologies for manufacturing syngas

Fluid gas gasifier

The fuel is fluidized in oxygen (or air) and steam

Steam reforming of natural gas

The primary process used in methanol production today

Combustion zone

Zone near the bottom of the gasifier, which operates at the highest temperature, where oxygen reacts withthe remaining char

Carbonization zone

Zone where cial is further heated and devolatized by the higher temperature gas as it descends

Drying zone

Zone where entering coal is heated and dried while cooling the product gas before it leaves the reactor

Gasification zone

Zone where the devolatized coal is gasified by reaction with steam and carbon dioxide

ZnO catalyst bed

Absorbs H2S and converts to ZnS and reduces sulfur to less than 0.1 ppm

Reduction of CO2 from flue gas with H2 from electrolytic splitting of water

Alternate routes to syngas

Presence of water as steam

Favors the reactions that yield fuel-gas

Pressure swing adsorption

Final process step of steam methane reforming

Methanol

First produced commercially in 1830 by pyrolysis of wood to produce wood alcohol

Large coal particles and fluxes

Fixed or moving bed feedstocks loaded into the top of the refractory-lined gasifier vessel and move slowly downward through the bed, while reacting with high oxygen content gas introduced at the bottom of the gasifier that is flowing counter-currently upward in the gasifier

95-99%

Fluid bed gasifiers converts about _______ range of carbon

Synthesis gas (syngas)

Gas mixture that contains varying amounts of carbon monoxide and hydrogen

90%

Gasification in fluid bed is efficient and exceeds ______ of feedstocks

Entrained flow gasifier

Gasification takes plaxe in a dense cloud of veryfine particles

Fluid bed gasifier

Gasifiers that feature extremely good mixing and good heat and mass transfer

Syngas

Generated by the gasification of carbon-containing fuel to a gaseous product with a heating value

Steam methane reforming

Generates syngas with H2/CO ratios in range of 3-4, which makes it suitable for hydrogen production

Underground coal gasification process

Given way to more favorable anx highly developed aboveground processes

Solid coke byproduct

Produced from coal gas processing

Blue water gas

Produced from complete gasification of coke by blasting hot coke with alternating amounts of steam and air

Steam methane reforming Autothermal reforming

Two main technologies for manufacturing syngas

Dry ash mode and slagging mode

Two modes of moving bed gasifier

Partial oxidation of methane

Typically much faster that steam reforming and requires small reactor vessel

Syngas

Used as intermediate in producing synthetic petroleum for use as fuel or lubricant via Fischer-Tropsch

Distilled coal gas

Used to fuel street lamps in London

Lignite

Very high moisture content andproduces raw gas at a temperature of around 600 F

William Murdoch

Distilled coal in an iron oven and used the coal gas to fuel lamps in his home

Entrained flow gasifier

Dry pulverized solid, an atomize liquid fuel or a fuel slurry is gasified with oxygen (air) in cocurrent flow

CH4 + 1/2O2 --> CO + 2H2 (+ heat)

Partial oxidation of methane reaction

Sulfur compounds

Present innatural gas feed, (or coal) which must be removed before or after synthesis gas production

Underground gasification process

Process involved blowing air into a coal seam through an injection well and then igniting the system

Fischer-Tropsch Process

Process involving the addition of methylene groups to a growing chain of carbon atoms

Natural gas

This replaced coal synthesis gas as the primary feedstock for methanol production

Distilled coal

Discover led to the development of the coal gas industry

Gasifiers

Available for commercial use, classified into fhree types: fixed (or moving) bed, fluid bed, and entrained flow

Catalytic version of partial oxidation

Based onshort contact time conversion of methane, hydrocarbons of biomass, which is suitable for small scale applications

Water gas shift reaction

CO + H2O --> CO2 + H2 (+ small heat)

Steam reforming

Can also be used to produce hydrogen from other fuels such as ethanol, propane and or gasoline

Pressure swing adsorption

Carbon dioxide and impurities are removed from the gas stream leaving essentially pure hydrogen

Water gas shift reaction

Carbon monoxide and stean are reacted using a catalyst to produce carbon dioxide and more hydrogen

CuZn catalyst

Catalyat used in production of methanol from synthesis gas

Rhodium

Catalyst used in catalytic version of partial oxidation

2H2 + CO ---> CH3OH CO2 + 3H2 ---> CH3OH + H2O

Chemical reactions in production of methanol from synthesis gas

Fixed/moving bed fluid bed entrained flow

Classification of gasifiers

Distilled coal gas

Contained about 50 % hydrogen, 20-30 % methane with remainder being principally carbon monoxide

Demetri mendeleev

Developed a process similar to underground gasification process

2

H2/CO ratio of partial oxidation of methane

3-4

H2/CO ratio of steam methane reforming

Lignite

Has very high moisture content

Autothermal reforming

Heat needed for reforming is generated inside the reactor by oxidation of the feed gas

Steam methane reforming

High temperature steam (700-1000 F) is used to produce hydrogen from a methane source such as natural gas

BASF and Dupont

Introduced the first synthetic methanol productiin processes

Autothermal reforming

Is a hybrid, which combines methane steam reforming and oxidation in one process

Bituminous coal

Lower moisture, produces gas at temperature of over 1000 F

Fischer and Tropsch

Made a major step in synthetic fuel chemistry, applied for a patent involving production of liquid fuel from carbon monoxide and hydrogen containing synthetic gas derived from coal

Moisture content of fuel

Main factor which determines the discharge gas temperature

Partial oxidation of methane

Methane and/or other hydrocarbons in natural gas react with a limited amount of oxygen (typically from air) that is not enough to completely oxidize the hydrocarbons to carbon dioxide and water

Steam methane reforming

Methane reacts with steam under 3-25 bars in presence of catalyst producing hydrogen, carbon monoxide and small amounts of carbon dioxide

Dry ash mode

Mode where as below the combustion zone is cooled by entering steam and oxidant (oxygen or air) and produced as a solid ash

Slagging mode

Mode where much less steam is used, and as a result, a much higher temperature is achieved in the combustion zone melting the ash and producing a slag

Dry ash mode

Mode where temperature is moderated to below the ash-lagging temperature by reaction of the char with excess steam

Entrained flow gasifier

Most coals are suitable for this type of gasifier because of high operating temperatures and because coal particles are well separated from one another

Coal synthesis gas

Nearly a century later, a process was developed by BASF to produce synthetic methanol from ______

Partial oxidation of methane

Non catalytic large scale process to make syngas

1

Number of distillation steps to produce fuel grade methanol

4

Number of distillation steps to produce methanol grade AA

Fixed ormoving bes gasifiers

Operate at moderate pressure (25-30 atmospheres)

Moving bed gasifier

Operate in two different modes

H2/CO ratio of 2

Optimal ratio for gas to liquids plant

Steam reforming or partial oxidation or methane or natural gas

Other methods of producing synthetic gas and hydrogen

Wood alcohol

Other name for methanol

Higher boiling alcohols Dimethyl ether (CH3OCH3)

Other products of methanol production process

Insufficient

Oxygen supplied in gasifiers

Gasifiers

Oxygen supplied is insufficient to produce complete combustion and presence of water as steam favors the reactions that yield fuel gas

Exothermic

Partial oxidation is an _______ process

Hydrogen Carbon monoxide Small carbon dioxide

Products produced from steam methane reforming

Methanol grade AA

Purest grade of methanol

Hydrogen Carbon monoxide Small carbon dioxide

Reaction products of partial oxidation of methane

Fixed or moving bed gasifiers

Reactions occur in different zones

Packed bed, fluidized bed, entrained or concurrent flow

Reactors for use in aboveground coal gasification

William Murdoch

Scottish engineer and partner of James Watt

Calorific value of coal gas

Served as benchmark for town gas industry that was to follow

Sulfur

Severely degrade and poisons the CuZn reforming catalyst

Endothermic

Steam reforming is an _______ process

CH4 + H2O + heat --> CO + 3H2 + 3H2

Steam-methane reforming reaction

Siemens

Suggested use of underground gasification process to derive gas from coal rsmaining in the ground after mining

Autothermal reforming

Suitable for large scale production of syngas for gas to liquids or large scale methanol synthesis processes

low-grade coals

Suitable for use in fluid bed gasifier since temperature are relatively low so fuel used must be reactive

Blue water gas

This fuel burned with a distinct blue flame

Partial oxidation of methane

This process intially produces less hydrogen per unit of input fuel than it is obtained by steam reforming of the same fuel

Blue water gas

Was composed of 50% hydrogen, 40% percent carbon monoxide and remainder being carbon dioxide and nitrogen

Partial oxidation of methane

Yields syngas with H2/CO ratio of about 2

Drying zone

Zone at the top of fixed or moving bed gasifier

COS + H2O <---> CO2 + H2S H2S + ZnO <---> ZnS + H2O

sulfur removal reactions

Byproduct solid coke

was a source of further fuel development during later years of nineteenth century