SU1544828A1 - Method of pretreating heat carrier for conveyer-type firing machines - Google Patents

Abstract

The invention relates to the production of iron ore in ferrous metallurgy, namely the production of agglomerated materials by means of their strengthening firing. The purpose of the invention is to improve product quality and reduce fuel and energy costs. When pellets are roasted on conveyor machines, gas streams are mixed in opposite jets by supplying high-temperature collector gas to the hearth from above through its roof, and lower-temperature recycle gas from the bottom to the heart of the hearth through the blowing chamber; towards the collector gas under a total pressure of up to 4 kg / m ² . Due to this, the uniformity of mixing of the gas flows is greatly increased. 1 ill., 1 tab.

Description

The invention relates to the production of iron ore in ferrous metallurgy, namely, to the production of agglomerated materials by means of their strengthening roasting.

The purpose of the invention is to improve product quality and reduce fuel and energy costs.

The uniformity of heat treatment of the layer, and therefore, the productivity of the kiln machines and the quality of the finished product, is mainly determined by the preparation of the coolant in the furnaces of the conveyor machines. In turn, the uniformity of heat treatment mainly depends on the conditions and parameters of the formation of the coolant in the hearth, the uniformity and level of thermal potential in it, the distribution of coolant over the area of the hearth. When burning fuel in the furnace, the creation of a uniform thermal floor requires the elimination (weakening of the effect) of the burning torch on the surface of the layer, adjusting the shape of the torch, and improving the mixing of the high-temperature torch core with secondary dilution air. ,

The method of mixing high-temperature heat transfer fluid with recirculation gas in opposing jets is carried out at practically the same pressure of both jets and replacing the rigid jet with a dispersed package of individual jets, which caused an increase in the uniformity of gas flow mixing by 3-4 times.

The mixing of the gas streams so opposing streams ensures that the high-temperature coolant flows into the furnace from above through its roof, and the lower-temperature supply from the bottom of the hearth of the furnace through the blast chamber located in the package of vacuum chambers. through the layer, it gives some of its heat to the evaporation of moisture and enters the furnace. At the exit of the layer being dried, the upper horizon of which is a natural solution With a living cross section of 0.28– 0.32, the gas stream is divided into separate dispersed jets and becomes in the bottom. The top gas stream is at the outlet from the overflow collector in its parameters close to the bottom one. The mixing of such flows is quite effective; a uniform temperature field is formed in the furnace with a gradual increment of the temperature potential along the hearth, which makes it possible to increase the average temperature potential in the furnace, gradually prepare the upper horizon to perceive high temperatures and eliminate formation processes in the piece. micro and macrocracks.

The pressure of the recirculated gas at the outlet from the layer is set to no more than 4.0 kg / cm. Thus, mixing of gas streams with similar characteristics in the opposite streams is ensured and a sufficiently uniform heat-transfer agent is obtained at the second stage of drying the pellets. When the gas pressure at the outlet of the layer exceeds 4 kg / m, the upper gas flow is blocked and the uniformity of the temperature field in the furnace decreases

The blow chamber in the vacuum package is placed in the front (along the material) group, if necessary, as much as possible of a decrease in temperature at the beginning of the hearth, in the middle group to increase the temperature potential in the whole of the hearth, or in the final

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group for setting on the path of high-temperature heat transfer fluid kneading gas curtain

The drawing shows a scheme that implements the method, with the installation of the blast chamber in the package before the vacuum.

The scheme includes the blast chambers 1, the first stage 2 of the hearth, the second stage 3 of the hearth, the overflow manifold 4, the output section 5, the blow 6 ° and the vacuum 7 chamber.

The table presents experimental data on the effect of the recirculated gas pressure on the mixing efficiency of gas streams in the second stage drying stage and the process of removing moisture from the layer of raw pellets. The experiments were carried out on aerodynamic stands and industrial roasting machines. The mixing efficiency of the gas streams was evaluated by the uniformity of the temperature field in the furnace. The experiments were carried out at the front location of the blast chamber in a vacuum package,

Example Raw pellets are subjected to two-stage drying before high-temperature treatment; At the first stage, the heat carrier outgoing from the subsequent sections at 250–300 ° C is used as a drying unit. This coolant is fed into the blowing chambers 1, is blown through a layer of pellets, removed from it by evaporation of 43% of the moisture of the pellets, sent to the hill 2 and dumped out of it from the system. In the second stage, in the hearth 3, the energy carrier is formed from a high-temperature (to ISO C) heat-transfer fluid supplied from the overflow manifold 4 through its outlet section 5 and recirculation gases (250–300 C) s fed through the blowing chamber 6. Both gas streams are mixed in the opposing structures x with the same gas-dynamic parameters of both jets. Thus, the pressure of the gas temperature streams from the overflow manifold and the recirculated gas at the outlet of the layer is the same and equal to 1.0 kg / m. Thus, they provide (see the table) mixing of the gas streams with an efficiency of 0.86, increasing the degree of moisture removal from the pellets and improving the quality of baked pellets (in detail). Pog

energy source at 550 ° C with a uniform temperature potential is sucked through a layer of pellets, completing the removal of moisture from them by 95%, is fed into vacuum chambers 7 and is also dropped from the system,

Increasing the pressure of the recycle gas is only possible up to 4.0 kg / m. For example, with a gas pressure of 4.5 kg / m4, the mixing efficiency of gas flows in the furnace 3 decreases by 14% and the content of fines immediately increases in the finished product (in 1/3 of the upper part of the bed twice, see table).

The control and regulation of the flow and temperature of all gas streams is carried out by traditional methods.

The application of the invention ensures the formation of the coolant directly in the second stage horn without burning external fuel, improving the quality of the calcined pellets (in particular, reducing the content of fines in it by 0.8-1.2%) and reducing the fuel and energy costs of the process (for fuel eleven%).

ten

Claims (1)

Invention Formula The method of preparing heat carrier 15 for calcining conveyor machines, including mixing of different-temperature gas streams from the overflow collector and the recirculation system, in which the pressure and pressure of the recirculation gas is 20 to improve the quality of the output from the layer is controlled by standard- and lowering fuel energetic diffractometer gauges and regulate the intake; the recirculation gas is filtered by changing the pressure in the blowing chamber 6 through a layer of drying the pellets and by means of serial throttling serves towards the collector gas dampers .. 25 under a total pressure of up to 4 kg / m. 448286 The application of the invention ensures the formation of the coolant directly in the second stage horn without burning external fuel, improving the quality of the calcined pellets (in particular, reducing the content of fines in it by 0.8-1.2%) and reducing the fuel and energy costs of the process (for fuel eleven%). ten Invention Formula 2 H d