A method and apparatus for protecting a furnace floor of a black liquor recovery boiler, where the furnace floor is covered by a protective layer, the protective layer being formed of a salt mixture including at least two different salts.

An assembly for cleaning a smelt spout includes a cleaning head, a drive rod connected with the cleaning head, and a pneumatic or other drive connected to selectively extend or retract the drive rod. The drive rod may be connected with the cleaning head by a pivotal connection. The cleaning head may be bifurcated. The cleaning head may include a leading edge configured to engage and clean a spout opening from which smelt from a chemical reduction furnace flows to the spout. The assembly may further include a pivot point and, as the drive selectively extends the drive rod, torque about the pivot point produced by the cleaning head and an extending portion of the drive rod rotates the cleaning head downward to engage a smelt spout.

An assembly for cleaning a smelt spout includes a cleaning head, a drive rod connected with the cleaning head, and a pneumatic or other drive connected to selectively extend or retract the drive rod. The drive rod may be connected with the cleaning head by a pivotal connection. The cleaning head may be bifurcated. The cleaning head may include a leading edge configured to engage and clean a spout opening from which smelt from a chemical reduction furnace flows to the spout. The assembly may further include a pivot point and, as the drive selectively extends the drive rod, torque about the pivot point produced by the cleaning head and an extending portion of the drive rod rotates the cleaning head downward to engage a smelt spout.

An apparatus comprising a cleaning rod driven in reciprocating, axial extension (y) and retraction (x) movements upon cleaning a smelt discharge opening of a chemicals recovery boiler, wherein a linear actuator is controllable for driving the cleaning rod in the axial movements. A pivot actuation means is controllable for pivoting the cleaning rod about an axis (S) upon cleaning a smelt spout associated with the smelt discharge opening, wherein one or more sensors are arranged to provide control basis for correlation of the axial movements (x; y) with the change in pivot angle (φ) during pivoting of the cleaning rod. A method to be performed in use of the apparatus is likewise disclosed.

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 and apparatus for protecting a furnace floor of a black liquor recovery boiler, where the furnace floor is covered by a protective layer, the protective layer being formed of a salt mixture including at least two different salts.

Scale build-up on metal surfaces of a black liquor evaporator is prevented or mitigated by treating the black liquor with a deposit inhibiting concentration of a water-soluble polymer containing a polycarboxylate chain and a 3-mercaptopropionic acid end group.

The method in a recovery boiler comprises estimating the first melting temperature T.sub.0 of the fly ash depositing on heat transfer surfaces, the estimating being based on potassium (K) content of the fly ash; measuring or estimating the temperature T.sub.ss of superheated steam; evaluating a temperature difference T.sub.D1 between the first melting temperature T.sub.0 and the temperature T.sub.ss of the superheated steam, the temperature difference T.sub.D1 providing an estimate of the risk of corrosion; and selecting a control action for influencing the temperature difference T.sub.D1. Alternatively or additionally, the method comprises estimating the sticky temperature T.sub.STK of the fly ash depositing on heat transfer surfaces, the estimating being based on potassium (K) and chlorine (Cl) contents of the fly ash; measuring or estimating the temperature T.sub.FG of the flue gases; evaluating a temperature difference T.sub.D2 between the sticky temperature T.sub.STK and the temperature T.sub.FG of the flue gases; the temperature difference T.sub.D2 providing an estimate of the risk of plugging; and selecting a control action for influencing the temperature difference T.sub.D2.

An apparatus comprising a cleaning rod driven in reciprocating, axial extension (y) and retraction (x) movements upon cleaning a smelt discharge opening of a chemicals recovery boiler, wherein a linear actuator is controllable for driving the cleaning rod in the axial movements. A pivot actuation means is controllable for pivoting the cleaning rod about an axis (S) upon cleaning a smelt spout associated with the smelt discharge opening, wherein one or more sensors are arranged to provide control basis for correlation of the axial movements (x; y) with the change in pivot angle () during pivoting of the cleaning rod. A method to be performed in use of the apparatus is likewise disclosed.

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.