Water gas

Water gas

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Water gas is a synthesis gas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

, containing carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...

. The gas is made by passing steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

 over a red-hot hydrocarbon fuel such as coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

:
H2O + C → H2 + CO (ΔH = +131 kJ/mol)


The reaction is endothermic
Endothermic
In thermodynamics, the word endothermic describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat. Its etymology stems from the prefix endo- and the Greek word thermasi,...

 so the fuel must be continually re-heated to keep the reaction going. This was usually done by alternating the steam stream with an air stream.
Required heat is provided by burning carbon.
O2 + C → CO2 (ΔH = −393.5 kJ/mol)

Theoretically to make 6 L of water gas, 5 L of air is required.

Or alternatively to prevent contamination with nitrogen, energy can be provided by burning pure oxygen into carbon monoxide.
O2 + 2 C → 2 CO (ΔH = −221 kJ/mol)

In this case 1 L of oxygen will create 5.3 L of pure water gas

History


The water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

 was discovered by Italian physicist Felice Fontana
Felice Fontana
Felice Fontana was an Italian physicist who discovered the water gas shift reaction in 1780. He is also credited with launching modern toxicology and investigating the human eye.-Early life:...

 in 1780. Water gas had been made in England since 1828 by blowing steam through red-hot coke, this water gas was carburized by petrol according to a process invented by Lewis Thompson and Hind (Singer 119). Charles Singer also states in his "A History of Technology" that, in the United States, natural gases were often used for carburizing (Singer 119).

Lowe's gas process


In 1873, Thaddeus S. C. Lowe
Thaddeus S. C. Lowe
Thaddeus Sobieski Coulincourt Lowe , also known as Professor T. S. C. Lowe, was an American Civil War aeronaut, scientist and inventor, mostly self-educated in the fields of chemistry, meteorology, and aeronautics, and the father of military aerial reconnaissance in the United States...

 developed and patented the water gas process by which large amounts of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 gas could be generated for residential and commercial use in heating and lighting. Unlike the common coal gas, or coke gas which was used in municipal service, this gas provided a more efficient heating fuel. The process used the water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

:
CO + H2O → CO2 + H2


The process was discovered by the passing of high-pressure steam over hot coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

, the major source of coke gas. Lowe's process improved upon the chimney systems by which the coal could remain superheated thereby maintaining a consistently high supply of the gas. This process created a thermo-chemical reaction of applying hydrogen, in the steam, to carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, in the coke gas. The reaction produced carbon dioxide and pure hydrogen which after a process of cooling and "scrubbing," passing through water vapor
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

, left just a pure hydrogen gas.

The process spurred on the industry of gas manufacturing, and gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

 plants were established quickly along the Eastern seaboard of the United States. Similar processes, like the Haber Process
Haber process
The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

, led to the manufacture of ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 (NH3) by the combining of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, found in air, with high volumes of hydrogen. This spurred on the refrigeration
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

 industry which long used ammonia as its refrigerant
Refrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...

. Prof. Lowe also held several patents on artificial ice making machines, and was able to run successful businesses in cold storage as well as products which operated on hydrogen gas.

Carburetted water gas


Water gas had a lower calorific value than coal gas
Coal gas
Coal gas is a flammable gaseous fuel made by the destructive distillation of coal containing a variety of calorific gases including hydrogen, carbon monoxide, methane and volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide and nitrogen...

 so the calorific value was often boosted by passing the gas through a heated retort
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...

 into which oil was sprayed. The resulting mixed gas was called carburetted water gas.

Semi-water gas


Semi-water gas is a mixture of water gas and producer gas
Producer gas
-USA:Producer Gas is a generic term referring to:* Wood gas: produced in a gasifier to power cars with ordinary internal combustion engines.* Town gas: manufactured gas, originally produced from coal, for sale to consumers and municipalities....

 made by passing a mixture of air and steam through heated coke. The heat generated when producer gas is formed keeps the temperature of the coke high enough to allow water gas to be formed.

Water gas shift reaction


Pure hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 can be obtained from water gas by using the water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

.

See also


  • Coal gasification
    Coal gasification
    Coal gasification is the process of producing coal gas, a type of syngas–a mixture of carbon monoxide , hydrogen , carbon dioxide and water vapour –from coal...

  • Fluidized bed
    Fluidized bed
    A fluidized bed is formed when a quantity of a solid particulate substance is placed under appropriate conditions to cause the solid/fluid mixture to behave as a fluid. This is usually achieved by the introduction of pressurized fluid through the particulate medium...

  • Fluidized bed combustion
    Fluidized bed combustion
    Fluidized bed combustion is a combustion technology used in power plants. Fluidized beds suspend solid fuels on upward-blowing jets of air during the combustion process. The result is a turbulent mixing of gas and solids. The tumbling action, much like a bubbling fluid, provides more effective...

  • Gasification
    Gasification
    Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

  • Gasifier
  • Isle of Wight gasification facility
    Isle of Wight gasification facility
    The Isle of Wight gasification facility is a municipal waste treatment plant in southern England. It entered the commissioning phase in autumn 2008...

  • Lane hydrogen producer
    Lane hydrogen producer
    The Lane hydrogen producer was an apparatus for hydrogen production based on the steam-iron process and water gas invented in 1903 by Howard Lane.-History:...

  • Linde-Frank-Caro process
    Linde-Frank-Caro process
    The Linde-Frank-Caro process is a method for hydrogen production by removing hydrogen and carbon dioxide from water gas by condensation. The process was invented in 1909 by Adolf Frank and developed with Carl von Linde and Heinrich Caro..-Process description:...

  • List of solid waste treatment technologies
  • Mond gas
    Mond gas
    Mond gas is a water-coal gas that was used for the production of ammonia and as fuel gas. The gas is named after its inventor Ludwig Mond. Mondgas has a high content of hydrogen, carbon monoxide, ammonia and volatile tar and a heating value 800 to 1500 kcal/Nm³.-History:In the 19th and 20 Century...

  • Plasma arc waste disposal
    Plasma arc waste disposal
    Plasma arc gasification or Plasma Gasification Process abbreviated PGP is a waste treatment technology that uses electrical energy and the high temperatures created by an electric arc gasifier. This arc breaks down waste primarily into elemental gas and solid waste , in a device called a plasma...

  • Pyrolysis
    Pyrolysis
    Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

  • Renewable natural gas
    Renewable natural gas
    Renewable natural gas, also known as sustainable natural gas, is a biogas which has been upgraded to a quality similar to fossil natural gas. A biogas is a gas methane obtained from biomass. By upgrading the quality to that of natural gas, it becomes possible to distribute the gas to customers via...

  • Town gas
  • Wood gas
    Wood gas
    Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of petrol, diesel or other fuels. During the production process biomass or other carbon-containing materials is gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen...