gasification

Gasification Technology

The CHALCO gasifiers operate at low pressure (5bara) and process about 350-550tpd of bituminous solid fuel as the gasification feedstock. The CHALCO gasifiers have been in operation since commissioning in 2015-2017.

The gasifiers in operation by CHALCO are: • Shandong Facility – 2x 500tpd gasifiers utilizing bituminous solid fuel, commissioned in 2015. • Shanxi Facility – 1x 350tpd gasifier utilizing a high ash bituminous solid fuel, commissioned in 2016. • Henan Facility- 4x 400tpd gasifiers, utilizing bituminous solid fuel, commissioned 2017.

The gasification technology has been developed by GTI Energy. The development hub for GTI Energy is based in Chicago, USA and includes a 20tpd development unit. AFC via its parent company Australian Future Energy (AFE), has an exclusive license to GTI Energy’s U-Gas gasification technology within Australia.

Production Process Flow Explained

  1. Feed Preparation:
    • Fort Coopers Middling’s waste solid fuel is crushed to a nominal size of 10-20 mm.
    • Biomass to include waste timbers from construction and demolition wastes that have lower moisture compared to green biomass.
    • Waste tyres are shredded with steel beading and steel belts removed.
  2. Gasification: The gasification process uses a fluidised-bed under moderate conditions of temperature and pressure (1,000°C, 5 to 15bar), with oxygen and steam as the gasification agents to convert the feedstocks to a syngas with high H2 and CO content. The steam injected into the gasification reactor is generated by heat-exchange with the hot (1,000°C) raw syngas leaving the gasifier, cooling the syngas. The steam reacts with carbon to generate CO and H2 via the steam gasification reaction C + H2O = CO + H2.
      • A pressure swing adsorption unit (PSA) is used to generate the oxygen for gasification. The oxygen purity is 95%. Some of the nitrogen by-product from the PSA unit is used for the first stage of lock hopper pressurization and for process purging. Captured CO2 is used for second stage lock hopper pressurization and solids feeding into the gasifier.
      • The gasifier achieves high carbon conversion (>98%) to syngas. Ash is discharged from the bottom of the gasifier. The ash is oxidized and non leachable and can be used as a road-base material.

  3. Syngas Treatment:

    • The hot, raw syngas is cooled (raising steam for process use) and wet scrubbed to remove particulates and water soluble (typically chlorides, HCl). o A sour shift reactor converts CO to CO2 and H2 via the water-gas shift reaction (CO + H2O = CO2 + H2). The sour shift reactor is tolerant to the presence of H2S/sulphur compounds.

    • A Selexol acid gas removal (AGR) unit separates CO2 and H2S from the syngas. A significant amount of the CO2 is used in urea production, with the remainder available for sequestration, enhanced oil recovery (EOR), or algae- based fuel production. Some CO2 is also used for lock hopper pressurization and solids feeding into the gasifier.

  4. Hydrogen Production:

    • A low-temperature water shift reactor converts additional CO to H2 and CO2.

    • The H2 is separated using Pressure Swing Adsorption (PSA) and sent to the ammonia synthesis loop.

  5. Ammonia Synthesis:

    • Hydrogen is reacted with nitrogen in the Haber process to produce ammonia (NH3) at 340°C and 142 bar pressure. o The ammonia synthesis loop is sized to produce 14 tph of ammonia or 113,000 tpa.

  6. AdBlue Urea Production:

    • The ammonia is combined with CO2 to produce urea using the Stamicarbon process, modified for IPCO Rotoform Pastillation.

    • The IPCO Rotoform system is used to create AdBlue-grade urea, producing 25 tph of urea with an annual output of 200,000 tpa.

Energy and Power Requirements

  • Total Site Power Requirement: 28 MW
  • Power Supply: The facility is designed to be self-sufficient in power generation, with tail gas and excess syngas powering gas engines (or gas turbines) to meet the full energy demand of approx. 28MW for the gasification, ammonia, and urea trains.
  • At times of low power pricing, it may be beneficial to import power from the grid. In this case, the plant can be turned down to reduce excess syngas production/power generation whilst maintaining ammonia/urea production.