Chemrec Aktiebolag

Kvaerner Pulping Ab

Kvaerner Pulping Technologies Ab

Kvaerner Pulping Aktiebolag

Kanyr Ab

Lars Stigsson

Bengt H Nilsson

Ake Backlund

Nils Bernhard

Mikael Linstrom

Ove Wallergard

&angst;ke Backlund

Nils Bernard

ANGke Backlund

The present invention relates to a process for producing pulp which is cooked under alkaline conditions and which is bleached without using chlorine-containing bleaching chemicals, in which process used cooking chemicals are recovered in a first recovery installation and used bleaching chemicals are recovered in a second recovery installation. The used cooking and bleaching chemicals can be regenerated and reused.

Totally chlorine free bleaching process using recovered filtrate

A method for impregnation and chemical digestion of lignocellulosic material and recovery of pulping liquors. A spent impregnating or cooking liquor is withdrawn and sulphurous compounds are recovered therefrom in a partial oxidation reactor. These sulphurous compounds are converted into hot liquid elemental sulphur which thereafter is mixed with a hot sulphide containing liquor to provide a polysulphide liquor with a concentration greater than 10 g/l and which is essentially free from thiosulphate. This polysulphide liquor is used for carbohydrate stabilising impregnation and/or for cooking at a relatively low temperature.

Polysulfide pulping process

Provided is a novel process for the preparation of an aqueous solution of alkaline compounds from a generator gas, containing carbon monoxide, carbon dioxide, hydrogen and entrained alkaline compounds, which gas has been formed during partial combustion of cellulose spent liquors in a gas generator connected to a quench vessel. The process includes the steps of:

Method for gasifying cellulose spent liquor to produce superheated steam

Method for the recovery of energy and chemicals from cellulose spent

The present invention is directed to a process for efficient combustion of cellulose spent liquors using a burner connected to a reactor, while supplying an oxygen containing gas, which invention is characterized in that more than 80% of the oxygen which is required for the partial combustion of the spent liquor is supplied through the lance of the burner to the reactor as an oxygen containing gas at a stoichiometric ratio of between 0.3 and 0.6 relative to complete combustion of the spent liquor.

Process for the partial combustion of cellulose spent liquor using twin

The process for producing hydrogen peroxide, used in the bleaching of pulp, uses the hydrogen generated wholly or partly by the gasification or partial combustion of cellulose spent liquors used in digesting cellulose material to produce the hydrogen peroxide.

Method for bleaching pulp with hydrogen peroxide recovered from

A method of separating sulphur compounds out of a gas containing carbon dioxide and hydrogen sulphide, in a gas washing system, said gas being obtained by gasification of spent cellulose liquor. According to the invention the gas washing system has a gas-liquid contact zone (5) operating at a pressure exceeding atmospheric pressure as well as a regeneration zone (8) operating at a pressure substantially less than the pressure in the gas-liquid contact zone (5). The carbon dioxide partial pressure in the gas prior to entering the gas-liquid contact zone exceeds 0.2 atm. Furthermore the gas comes into contact with an alkaline absorption liquid in the gas-liquid contact zone, and alkaline liquid containing alkali hydrogen sulphide is withdrawn from the gas-liquid contact zone and transferred to the regeneration zone, in which zone hydrogen sulphide is expelled from said liquid containing alkali hydrogen sulphide and withdrawn in the form of a gas.

Method of seperating sulphur compounds

Process for recovering energy from a combustible gas

Process for the partial combustion of cellulose spent liquor using

The present invention relates to a process for the separation of sulphur and sodium compounds from a hot process gas generated during gasification of spent liquor from the kraft pulping industry, through contact with hydrogen sulphide ion and hydroxide ion containing alkaline liquids in two or more stages, whereby the process gas in a first stage passes through a venturi throat and/or liquid trap where it is brought into contact with an alkaline washing liquid, whereby melt droplets in the process gas are separated from the gas flow and drawn off as an aqueous solution, whereby the process gas in a subsequent washing stage is brought into contact with a finely dispersed washing liquid containing hydroxide ions and hydrogen sulphide ions with a molar ratio greater than 4:1.

Growing community of inventors

Hammaro, Sweden

Lars Stigsson