Natural Gas

Natural Gas

General Info
1. Deal with NG Associated with Oil
  1. flaring
  2. injected into reservoir to maintain pressure
2. First found 19th century associated with oil production
3. Composition
  1. Sat, Aliphatic hydrocarbons
    1. straight chain
      1. greatest proportion methane > 50%
        Melting point – 182.5 °C
        Boiling point – 161.6 °C
        ΔHc° = - 882.0 kJ/mol
        Colourless
      2. Alkanes with up to C6
    2. branched alkanes
  2. Unwanted
    1. Gases CO2/H2S/N2/Hg
    2. H2O+Salt
    3. Mercaptans CH3SH
      1. detect leaks to distinct smell
4. Type
  1. Wet < 85% C1
  2. Dry almost C1 Natural or purified
Liquid Natural Gas for easy Transportation
1. Reduce V to 600 fold @ -162 oC
  1. Aluminium container and Hg Below level of detection and No water
Used for
1. Domestic – Heating and Cooking
2. Commercial – Heating, transport fuel, etc.
3. Electric Generation
4. Industrial
  1. Critical Industrial Reactions
    1. Steam Reforming
      1. CH4 + H2O ==>CO + 3H2 – syn gas
      2. Highly endothermic 900 °C @at high pressure
      3. Tubes are heated in a furnace
    2. Water – gas shift
      1. thermodynamically favoured by low temperatures
        CO + H2O ==>CO2 + H2
      2. ُُEquilibrium reaction
      3. Industrially
        High Temperature Shift
        iron oxide catalyst
        Low Temperature Shift
        CuO/ZnO/Al2O3
    3. Fischer – Tropsch
      1. 2n H2 + CO ==> -(CH2)n- + H2O
        Steam Reformation products enter the reactor
        catalyst Iron or Cobalt
        Products
        Olefins / Alkenes
        Paraffins / Alkanes
        Oxygenates
        Aromatics
    4. Methanol synthesis
    5. Ammonia synthesis
      1. N2 + 3H2 ==>2NH3
        Fe catalyst
        reaction is exothermic
        favoured by low temperatures
        high pressures
    6. A substance that promotes the rate of reaction by providing an alternative reaction pathway, and is regenearated at the end
      1. Homogeneous Catalysts
        Same as the reactants gas or liquid
        Not common/Hard to separate
        Examples are use of KOH
      2. Heterogeneous Catalysis
        different phase as the reactants solid
        Common, as separation is easy
Combustion of Natural Gas produce CO2 and water
1. Advantages of Burning Natural Gas
  1. Fewer emissions
  2. Reduced sludge from scrubbing SO2
2. Gas Burn is determined by
  1. CV , measure of heat released when it is burnt. Measured normally in Btu’s
    1. Wobbe Number =(Calorific Value)/√(Specific Gravity)
      1. same wobbe number ==> same amount of heat
  2. SG, much gas will pass through the orifice of a burner in a set time at a given pressure
  3. Burning Velocity Measures the speed at which a flame is propagated in a gas
3. Burning Gas problem
  1. Light Back
  2. unstable flame
  3. low flame speed gas

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	Created by Jacky Kim about 9 years ago