A process for the production of potassium sulphate by conversion of potassium chloride and sulphuric acid using a muffle furnace, said furnace comprising a reaction chamber and a combustion chamber, wherein in the reaction chamber potassium chloride (KCI) and potassium hydrogen sulfate (KHSO.sub.4) are reacted to form potassium sulphate while supplying heat to the reaction chamber from the combustion chamber, wherein the combustion chamber has at least a pair of regenerative burners and wherein the process comprises the steps of alternatingly causing one of the regenerative burners to perform a combustion operation in the combustion chamber to heat the reaction chamber and another of the regenerative burners to perform a heat-regenerating operation in a regenerator, wherein the pressure in the combustion chamber is kept at a pressure of between 0.2 and 3 mbarg.

A combustion method in which heated flue gas heats a regenerator through which a mixture of fuel and flue gas is then passed to undergo endothermic reactions that produce syngas which is fed into a furnace together with a motive gas stream, wherein fuel is combusted with the motive gas stream to provide heat in alternate cycles.

A heat-recovering oven system based on temperature gradient comprises: multiple chambers arranged in a sequence, the chambers configured for operating at various temperatures according to a temperature gradient arrangement that spans the sequence; a conveyor configured for transporting product through the multiple chambers in the sequence for heat treatment according to the temperature gradient arrangement; and multiple temperature-segregated heat exchanger systems, each heat exchanger system including a heat exchanger, a conduit to at least one of the chambers based on its temperature in the temperature gradient arrangement, and a return conduit from the at least one chamber to the heat exchanger.

An oxy-fuel boost burner for a regenerative furnace having a pair of regenerator ports configured to alternately fire into and exhaust from the furnace, including at least one burner element corresponding to each of the regenerator ports by being positioned to fire into a complimentary region of the furnace, each burner element including a selective distribution nozzle configured to flow a first reactant and a proportional distribution nozzle configured to flow a second reactant, and a controller programmed to identify which regenerator port is currently firing and which is currently exhausting and to independently control the first reactant flow to each selective distribution nozzle such that the at least one burner element corresponding to the currently firing regenerator port has a greater than average first reactant flow and the at least one burner element corresponding to the currently exhausting regenerator port as a less than average first reactant flow.

An industrial furnace for heating products such as steel products includes a thermally insulated enclosure, a plurality of burners arranged in the enclosure for heating products passing from one end of the enclosure to the other, the burners being distributed over a plurality of temperature-regulated heating areas, and a recovery system designed for recovering heat energy from recovery fumes, The recovery system includes a rotary regenerator associated with each heating area, each of the rotary regenerators being configured to receive a predetermined flow rate of recovery fumes via a first duct, receive a predetermined flow rate of supply air via a second duct, preheat the supply air in order to supply the burners of the associated heating area with a predetermined flow rate of preheated combustion air via a third duct, and discharge exhaust fumes via a fourth duct.

A thermally efficiency regenerative air preheater 250 extracts more thermal energy from the flue gas exiting a solid fuel fired furnace 26 by employing an alkaline injection system 276. This mitigates acid fouling by selectively injecting different sized alkaline particles 275 into the air preheater 250. Small particles provide nucleation sites for condensation and neutralization of acid vapors. Large particles are injected to contact and selectively adhere to the heat exchange elements 542 and neutralize liquid acid that condenses there. When the deposit accumulation exceeds a threshold, the apparatus generates and utilizes a higher relative percentage of large particles. Similarly, a larger relative percentage of small particles are used in other cases. Mitigation of the fouling conditions permits the redesign of the air preheater 250 to achieve the transfer of more heat from the flue resulting in a lower flue gas outlet temperature without excessive fouling.

Employing furnace combustion gases for both thermochemical regeneration and heating of regenerators to preheat oxidant for the furnace provides synergistic efficiencies and other advantages.

Disclosed is a thermochemical regenerative combustion method in which a mixture of fuel components that can, and cannot, undergo endothermic reaction is passed through a heated regenerator to obtain improved heat recovery efficiency.

Disclosed is a method of operating a furnace containing a charge to heat the charge, comprising wherein gaseous oxidant comprising 60 vol. % to 85 vol. % oxygen is passed through a heated regenerator and into the furnace, so that the oxidant is heated to emerge from an oxidant port at a temperature of 500 C. to 1400 C., and gaseous fuel is fed into said furnace through two or more fuel ports; and the heated oxidant and fuel are combusted in the furnace to produce gaseous hot products of said combustion which heat the charge; and then the flow of oxidant through the regenerator into the furnace is discontinued, and said combustion products are passed into said oxidant port and through and out of said cooled regenerator to heat said regenerator, wherein the temperature of the combustion products that pass out of said regenerator is at least 500 C.; under dimensional and operational conditions which attain functional and economic advantages.

Disclosed is a thermochemical regenerative combustion method for fuel containing ammonia and/or other low BTU bio-fuels to achieve fuel efficiency equal to or better than conventional fuels such as hydrogen and natural gas.