An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct comprising vertical flue gas channels, at least part of which is provided with heat recovery units for recovering heat from flue gases. The heat recovery units have a width of substantially the width of the flue gas duct, whereby downstream of the furnace the first flue gas channel is provided with a superheater. In addition to the superheater, the first flue gas channel is provided with one of following heat recovery units: an economizer, a boiler bank, or a reheater. The superheater and a second heat recovery unit are located one after the other in horizontal introduction direction of the flue gas, so that in a flue gas channel the flue gas flows in the vertical direction downwards and heats the superheater and the second heat recovery unit simultaneously.

A method for obtaining information on quality of combustion of a liquor in a chemical recovery boiler. The method comprises entering a value of a first input parameter to a computational model configured to determine, based on the value of the first input parameter, a value of the quality of combustion of the liquor in the chemical recovery boiler, and at a first time, running the computational model to obtain a first modelling result. The method comprises measuring, from the chemical recovery boiler a value indicative of carryover to obtain a measurement result; comparing the first modelling result with [a] the measurement result or [b] a result derived from the measurement result, to obtain a primary comparison result; and adjusting the value of the first input parameter based on the primary comparison result to obtain an adjusted value of the first input parameter. The method comprises entering the adjusted value of the first input parameter to the computational model, and at a second time, running the computational model to obtain the information on quality of combustion of the liquor in the chemical recovery boiler.

A disruptor adjustment system comprising: a disruptor assembly configured to disrupt a volume of smelt flowing from a smelt spout into a dissolving tank, wherein the disruptor assembly comprises an actuator operatively engaged to a disruptor, a sensor configured to record process data from the recovery boiler; and a control system configured to receive a sensor output signal from the sensor, wherein the sensor output signal indicates the process data at a measured time, wherein the control system is further configured to compare the sensor output signal to a programmed operation range, and to send a disruptor input signal to the disruptor assembly to adjust a disruptor operating condition if the process data of the sensor output signal is outside of the programmed operation range. In certain exemplary embodiments, the sensor is an image capture device. In certain exemplary embodiments, the disruptor assembly can be adjusted remotely.

A disruptor adjustment system comprising: a disruptor assembly configured to disrupt a volume of smelt flowing from a smelt spout into a dissolving tank, wherein the disruptor assembly comprises an actuator operatively engaged to a disruptor, a sensor configured to record process data from the recovery boiler; and a control system configured to receive a sensor output signal from the sensor, wherein the sensor output signal indicates the process data at a measured time, wherein the control system is further configured to compare the sensor output signal to a programmed operation range, and to send a disruptor input signal to the disruptor assembly to adjust a disruptor operating condition if the process data of the sensor output signal is outside of the programmed operation range. In certain exemplary embodiments, the sensor is an image capture device. In certain exemplary embodiments, the disruptor assembly can be adjusted remotely.

An anaerobic digestion system may include a material grinding/pulping portion, a hydrolysis portion arranged downstream of the grinding portion, a multiple chamber anaerobic reactor arranged downstream from the hydrolysis portion and including a gas collection and reintroduction system, a collection system for collecting digestate and gas from the anaerobic reactor.

Disclosed is a process for reducing slag in a black liquor recovery boiler, the process comprising: injecting and burning black liquor in a boiler by contacting it with primary air and secondary air; introducing a slag-reducing chemical into the gases above the injection locations through interlaced, tangential or concentric secondary, tertiary, and/or quarternary air ports.

Disclosed is a process for reducing slag in a black liquor recovery boiler, the process comprising: injecting and burning black liquor in a boiler by contacting it with primary air and secondary air; introducing a slag-reducing chemical into the gases above the injection locations through interlaced, tangential or concentric secondary, tertiary, and/or quarternary air ports.

A process for the preparation of small aromatic compounds from black liquor comprising: providing black liquor that derives from alkaline treatment of wood chips; subjecting the black liquor to a pyrolysis treatment to yield a pyrolysed black liquor gas and a solid mass comprising char and salts in a first reactor, wherein the salts substantially derive from the treatment of black liquor; contacting at least part of the pyrolysed black liquor gas with a catalyst in a second reactor, which is different from the first reactor to provide a conversion treatment to yield a conversion product; and recovering small aromatic compounds from the conversion product.

The disclosure provides methods and compositions for reducing the viscosity of black liquor. Also provided are methods of inhibiting deposition of scale and methods of processing black liquor. In some embodiments, the compositions include a carboxylate-containing polymer and an inorganic salt. In some embodiments, the compositions include a carboxylate-containing polymer, an inorganic salt, and a surfactant.

A method for controlling carryover in a chemical recovery boiler. The method comprises feeding black or brown liquor to a furnace of the chemical recovery boiler through an injection gun to burn the black or brown liquor. The chemical recovery boiler comprises a bullnose, which narrows the furnace, and a first superheater, of which at least a part is arranged at a higher vertical level than the bullnose. The method comprises measuring information indicative of a spatial temperature distribution on a cross section of the furnace, wherein the cross section is above the injection gun and below the first superheater; determining primary information indicative of carryover using the information indicative of the spatial temperature distribution on the cross section of the furnace; and controlling a temperature of the black or brown liquor that is fed to the furnace using the primary information. In addition, a system for performing the method.