BLACK LIQUOR

Listing description

In industrial chemistry, black liquor is the waste product from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers.

Detailed description

Usage

The black liquor contains more than half of the energy content of the wood fed into the digester of a kraft pulp mill.^[5] It is normally concentrated to 65 - 80% by multi-effect evaporators and burned in a recovery boiler to produce energy and recover the cooking chemicals. The viscosity increases as the concentration goes up. At about 50 - 55% solids the salt solubility limit is reached.^[6] Tall oil is an important byproduct separated from the black liquor with skimming before it goes to the evaporators or after the first evaporator stage.

Energy source for the pulp mill

Pulp mills have used black liquor as an energy source since at least the 1930s.^[7] Most kraft pulp mills use recovery boilers to recover and burn much of the black liquor they produce, generating steam and recovering the cooking chemicals (sodium hydroxide and sodium sulfide used to separate lignin from the cellulose fibres needed for papermaking). This has helped paper mills reduce problems with water emissions, reduce their use of chemicals by recovery and reuse, and become nearly energy self-sufficient by producing, on average, 66 percent of their own electricity needs on-site.

In the United States, paper companies have consumed nearly all of the black liquor they produce since the 1990s.^[7] As a result, the forest products industry has become one of the United States' leading generators of carbon-neutral renewable energy, producing approximately 28.5 terawatt hours of electricity annually.

Use as biofuel feedstock

New waste-to-energy methods to recover and utilize the energy in the black liquor have been developed. The use of black liquor gasificationhas the potential to achieve higher overall energy efficiency than the conventional recovery boiler while generating an energy-rich syngasfrom the liquor. The syngas can be burnt in a gas turbine combined cycle to produce electricity (usually called BLGCC for Black Liquor Gasification Combined Cycle; similar to IGCC) or converted through catalytic processes into chemicals or fuels such as methanol, dimethyl ether (DME), or F-T diesel (usually called BLGMF for Black Liquor Gasification for Motor Fuels). This gasification technology is currently under operation in a 3 MW pilot plant at Chemrec’s^[8] test facility in Piteå, Sweden. The DME synthesis step will be added in 2011 in the "BioDME" project, supported by the European Commission's Seventh Framework Programme (FP7) and the Swedish Energy Agency.^[9]

Used for biofuels production the black liquor gasification route has been shown to have very high conversion efficiency and greenhouse gasreduction potential.^[10]

Extraction of lignin

Where recovery boiler capacity is limited and a bottleneck in the pulp mill the lignin in the black liquor may be extraordinary and exported or used as fuel in the mill's lime kiln, thereby often replacing fossil based fuel with biofuel.

PRICE

$550/MT OR $0.55/KG OR $0.25/IB

For more information:

mobile: +2348039721941

contact person: emeaba uche

e-mail: emeabau@yahoo.com

website: www.franchiseminerals.com