A thermochemical regenerator system is operated without encountering accumulation of unwanted solids on the interior surfaces of the passages through which flue gas passes.

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.

Thermochemical regeneration is enhanced by injecting fuel gas to entrain recycled flue gas that passes out of a regenerator to form a mixture that is impelled into the other regenerator.

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

An apparatus for production of burnt lime or dolomite has: a shaft furnace having a preheating zone, a reaction zone, a separation zone and a cooling zone; a first feed apparatus for CO.sub.2 at the boundary of the separation zone to the reaction zone; a first removal apparatus at the boundary of the cooling zone to the separation zone; a second removal apparatus for CO.sub.2 at the start of the preheating zone; and at least one heating apparatus, wherein the heating apparatus has a regenerator system.

The regenerator system has at least two regenerators, a preheater, a feed for fuel and a feed for fresh air; the second removal apparatus opens into the at least one heating apparatus; and the first feed apparatus is formed by the at least one heating apparatus for the shaft furnace.

A method for operating a blast furnace plant that includes a blast furnace, at least one material hopper for charging raw materials to the blast furnace, having a upper seal valve and a lower seal valve, and at least one hot stove that produces hot blast for the blast furnace, the method including at least one charging cycle with the following steps: opening the upper seal valve, introducing raw materials into the material hopper, closing the upper seal valve, pressure equalization of the material hopper with blast furnace top pressure, and opening the lower seal valve to discharge raw materials into the blast furnace, wherein, in order to provide a cost-effective way to minimize the explosion danger during operation of a top charging system, an offgas from the at least one hot stove is transferred by a transfer system to the at least one material hopper and, before the lower seal valve is opened, the offgas is injected into the material hopper.

Techniques for utilizing excess heat generated by an oven to generate electricity are provided. In one example, an oven can comprise a coolant pathway positioned adjacent to a hollow space within the oven, wherein the hollow space can contain heat. The oven can also comprise a chamber in fluid communication with the coolant pathway. The oven can further comprise a turbine in fluid communication with the chamber and an outlet. Moreover, the oven can comprise a generator connected to the turbine, wherein rotation of the turbine can power the generator.

Techniques for utilizing excess heat generated by an oven to generate electricity are provided. In one example, an oven can comprise a coolant pathway positioned adjacent to a hollow space within the oven, wherein the hollow space can contain heat. The oven can also comprise a chamber in fluid communication with the coolant pathway. The oven can further comprise a turbine in fluid communication with the chamber and an outlet. Moreover, the oven can comprise a generator connected to the turbine, wherein rotation of the turbine can power the generator.

Furnace operation includes consecutive cycles of a heating step, a stopping step and a restarting step. The fuel and/or the oxidizing agent is preheated upstream of the furnace by indirect exchange with the discharged fumes through a medium passing through a chamber. A first wall separates the fumes from the medium in the chamber. The fuel and/or oxidizing agent is separated from the medium in the chamber by second wall. During restarting, the medium's flow rate Dm is regulated to limit the heating rate of the first wall until it reaches the operational temperature at an end thereof.

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