52results about "Green and white liquor treatment" patented technology

A system for controlling a processor having at least one sampling port connected to a stage of the processor in order to sample a reactant product from the processor. The system includes a controller configured to control a processing parameter of the processor based on measurements of at least one property of the reactant product such that changes to the processing parameter maintain a target value for the at least one property of the reactant product. The system further includes a dead time compensator. The dead time compensator is configured, based upon a prescribed dead time related to a time before at least one effect of at least one change to the processing parameter is fully realized, to evaluate the reactant product to determine if the effect has been realized at a plurality of sequential times offset from the dead time.

The method and an arrangement are for dewatering and washing lime slurry before the dewatered lime mud is passed to a lime mud kiln. The lime slurry is dewatered in a pressurized lime mud filter of disc or drum type. The pressurized lime mud filter is pressurized through a compressor drawing on its suction side (s) gas phase from the filtrate tank and pressurizing on the pressurized side (p) of the compressor the pressure vessel on the lime mud side of the filter. A certain pre-determined amount of gas phase in the gas circulation system is vented and an equivalent pre-determined amount of fresh air is added to the recycled gas phase with the aim of maintaining the partial pressure of oxygen gas above a certain minimum level.

Inexpensive spindle- or rice-like calcium carbonate giving useful properties for brightness, opacity and wire abrasion resistance as a paper filler is provided by taking advantage of the causticization step. When a white liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 10% by weight or less and is slaked with the white liquor at a concentration of 20 to 60% to prepare a milk of lime. When a green liquor is used for slaking a quick lime, the quick lime used in the slaking reaction of a first step has a calcium carbonate content of 0.1 to 10% by weight and is slaked with the green liquor at a concentration of 20 to 60% to prepare a milk of lime. In a second step, causticization reaction takes place at a green liquor loading rate of 0.02 to 0.5 cc (green liquor)/min/g (quick lime) at a reaction temperature of 20 to 105° C. to afford spindle- or rice-like calcium carbonate.

In a method for processing flue gases, flue gases from an incineration plant for non-condensable gases of a kraft pulp mill are scrubbed by means of a calcium compound. The calcium compound is lime mud taken from the chemical recirculation of the kraft pulp mill after causticization and before a lime reburning kiln, and it is used in the scrubbing of gas as a substance reacting with sulphur dioxide.

This application discloses exemplary processes and systems for reducing mineral ring accumulation in calcination kiln. The processes and systems comprise inserting non-condensable gases (“NCGs”) in a preheating zone of a calcination kiln, upstream of the burner end. The pre -heating zone may be characterized by temperatures ranging from 1,300° F. to 1,750° F. The system may desirably comprise a plenum for inserting the NCGs into the rotating calcination kiln at the pre-heating zone.

A method for obtaining particulate calcium carbonate exhibiting improved brightness and color and having uniformity of size such that when the particles are formed in the causticization process in a kraft pulp mill, the time required to separate the particles from liquors in which they are suspended is minimized and the amount of liquor recovered is maximized, with minimal dilution by water used for washing. The method includes the steps of a) slaking calcium oxide in water or an alkaline liquor containing as dissolved species predominantly sodium hydroxide; b) mixing the slaked lime with green liquor from a kraft pulping process to complete a causticization reaction that produces white liquor and lime mud; c) separating the lime mud from the white liquor; and d) milling a portion of the lime mud for use as a white mineral pigment in applications where such pigments are typically used.

The method is for preparation of white liquor in a chemical recovery process of the kraft process. The green liquor separation process and the white liquor separation process are taking place in the same common filter apparatus with no dedicated green liquor separation apparatus or any dedicated white liquor separation apparatus. The white liquor separation process and the green liquor separation process are conducted in sequence in the same filter apparatus. The white liquor separation process has a part of the cycle time in the range 20-50% of the total cycle time in the same filter apparatus.

The invention discloses a method for comprehensively recycling pulping waste liquid, which comprises the following steps: extracting dilute black liquid from pulping cooking liquid, pretreating the dilute black liquid, and finally evaporating and concentrating the pretreated dilute black liquid by using a mixed-flow indirect evaporation method; then performing combustion with a jet furnace so thathigh-temperature flue gas generated after organic matters in the black liquid are combusted rises in the furnace, and inorganic matters are molten, flow into a dissolving tank from a chute below thecombustion furnace and dissolved in dilute white liquid or water to form green liquid, with the green liquid comprising Na2CO3 and Na2S; carrying out a causticization reaction on the green liquid formed by inorganic melt dissolved in dilute white liquid or water; and finally, recycling a product generated by the causticization reaction of the green liquid. According to the method, the problems ofserious pulping and papermaking wastewater pollution and high treatment difficulty in the prior art are solved.

A method and a liquor filter, in which liquor filter sealing medium is fed via a sealing medium channel (3) into an innermost sealing zone formed by an innermost sealing member (1), an outer seal (2) and the space between them at a causticizing plant of a chemical pulp mill. The sealing medium used is an alkaline sealing liquid and/or gas, which does not substantially dilute the liquor being filtered. Advantageously the sealing medium is filtrate from the liquor filter and/or gas taken from the interior of the liquor filter.

The invention discloses a wheat straw pulp black liquor alkali recovery method. The method includes the following steps that firstly, black liquor is evaporated and concentrated, and the concentration of the concentrated black liquor is 40-44% after evaporation; secondly, the concentrated black liquor obtained after evaporation is further evaporated and concentrated through tertiary air by means of a disk evaporator and then enters an alkali furnace to be pyrolysed and combusted, and finally green liquor is prepared in a dissolving tank; thirdly, the green liquor is processed in a causticizing department, the green liquor obtained in the second step and an excessive amount of ash are placed in a causticizing devuce, causticizing temperature is higher than 95 DEG C, and white liquor is obtained after filtration. According to the method, the technological process is simple, investment is small, and lignin is recycled while organic matter dyeing loads are reduced, wherein the concentration of the green liquor is 110-120 g/L, the amount of the excessive amount of ash is 3-5%, the causticizing degree is larger than 85%, the amount of white mud residual alkali is smaller than 2%, the dryness degree of white mud is larger than 50%, and the concentration of the white liquor is larger than 80g/L.

The method and equipment relates to the measurement of deflections of filter sectors in a disc filter. The filter discs in the disc filter are constituted by a number of filter sectors, and the distance between a position fixed relative to the filter, most commonly the scraper itself, and the filter surface is conventionally measured by manual measurement methods. The equipment is instead used that has a measuring head with a quick-release coupling for its mounting fixed in the filter, and a position sensor in the measuring head that measures the distance between the measurement arrangement and the surface of the filter disc in order to form momentary measurement results. The momentary measurement results are transferred by a data transfer link from the measurement arrangement to a data collection unit PC that has a memory.

The invention discloses a control method for frequency conversion regulation of a causticizing green liquor system. Frequency conversion of the causticizing green liquor system is modified, stepless speed regulation of a frequency converter is used for replacing an electric valve control mode of an original green liquor system, and the technical problems that the opening degree of a valve is difficult to adjust, errors are large, precision is low, a green liquor conveying pipeline is prone to scaling, and the liquid level of a green liquor tank is difficult to control are solved.