SU933713A1 - Metal production furnace tuyere - Google Patents

Description

(5) FOURNA METALLURGICAL FURNACE

I

This invention relates to ferrous metallurgy, in particular, to submersible and bottom tuyeres for blowing liquid metal and the construction of tuyeres for blast furnaces.

At present, there has been a marked vie-, the use of heat pipes in the construction of tuyeres in order to increase their durability, as well as to prevent water from entering the purge volume during burnout of the tuyeres body.

A known blast furnace tuyere, intended for the flow of gas into a flare of a blast furnace, is made of separate cylindrical heat pipes rigidly fixed with a flange between them, while their ends are brought out in a water cooler l.

However, such use of heat pipes in the construction and tuyere has the following disadvantages: when the length of the tuyere exceeds 1 m, the capillary tube

The material located on the entire inner surface of the heat pipe is a significant hydraulic resistance and, even when working in the direction of gravity, does not provide the required heat flow to the evaporation zone, which causes heat pipes to burn out. In addition, in the joint zone of two adjacent heat pipes, heat transfer from the tuyere body to heat pipes is significantly degraded due to thermal resistance of the walls. It is also impractical to use in a single tuyere a large number of tubes that require a substantial increase in fueling. scope of work.

Closest to the invention in technical essence and the achieved result is a lance of a metallurgical furnace, comprising a body made in the form of a heat pipe, and a heat exchanger. In this design of the tuyere, in order to ensure uniform wettability of the capillary-t of the porous material, the working fluid was fed along the whole length of the tuyere heat supply zone. In to the working medium, low-temperature heat transfer fluids are used, which are unable to ensure the removal of large radial heat fluxes of 5.106-tO; W / m at the temperature of the PSO-EPO C structure, which takes place in the tuyeres to purge the liquid metal. So, if water is used as a coolant, the specific heat flux on capillary-porous surfaces does not exceed tOO W / d, while heat pipes with heat carrier - sodium provide a specific heat flux of up to 1250 W / Obviously, in immersion Only high-temperature heat pipes f2j can be used with tuyeres. However, when used in heat pipes with liquid-metal heat transfer agents, difficulties arise associated with their cooling. The supply of cooling water to the heat pipe cooling surface heated to a temperature of 600–900 C after its start with a relatively low pressure of 5–8 kg / cm existing in the grid of industrial enterprises leads to film boiling on the heat exchange curvature. Increasing the pressure to a value that suppresses film boiling on the heat exchange surface of 300 - AOO kg / cm is impractical because of the need to significantly increase the wall thickness of both the heat pipe body and the heat exchanger, which also leads to an increase in thermal resistance of the system, a significant increase in weight construction and will also require the creation of a high pressure feed system. The use of gas, due to its low efficiency as a cooler, leads to an increase in the dimensions of the tuyere due to a significant increase in the length of the heat exchanger. Another difficulty associated with the use of water or air as a cooler is that in practice it is often impossible to determine with the necessary accuracy the amount of heat flux existing in the heating zone, the tuyere, and therefore the flow rate of the cooling agent per the heat exchanger is exhausted at the maximum possible heat flux. In this case, any decrease in the amount of heat input and a delay in the actuation of the bond, which reduces the flow rate of the cooling agent, leads to the overcooling of the liquid metal heat pipe, a decrease in the transmitted heat flow, which leads to burnout of the tuyere. Thus, an alternative arises: to increase the durability of the tuyere using heat pipes with liquid metal coolants, it is necessary either to deny water as a refrigerant or using water to significantly complicate and weaken the design of immersion blast tuyeres, which is also their durability. The purpose of the invention is to create a construction of increased durability. This goal is achieved by the fact that a lance of a metal furnace is known, made in the form of a heat pipe with a heat exchanger, equipped with a thermosyphon with a liquid metal coolant installed in the heat sink section of the tuyere, and the heat exchanger is mounted on a thermosyphon. At the same time, in order to increase the heat transfer efficiency, in the heat exchange section between the lance body and the thermosyphon, the latter is provided with a perforated bottom deflector installed in the inner cavity t of the thermosyphon equidistantly heat sink surface, the height of the vent deflector being comparable with the length of the heat sink surface of the thermosyphon. An indispensable condition for the normal operation of such a design of the tuyere is the use of a liquid metal coolant as the working medium of a thermosyphon, which preserves its liquid state under conditions such as Na-k. Nq Eutectic with ratio K. freezing point which is tj "-). The diagrammatic drawing shows a submerged tuyere for purging liquid metal. The submerged lance consists of a body 1, the inner surface of which and the tip 2 are lined with a capillary material 3 filled with a heat carrier (preferably sodium). A thermosiphon j, filled with coolant to the level of burial in the thermosyphon C of housing 1, is installed at the opposite end of the tip of case 1. Both case 1 and thermosyphon k are evacuated before filling with coolant. The depot section 5 of the tuyere body in the thermosyphon is the condensation and heat sink section of the cGT of the housing 1. to the thermosyphon C.

On the outer surface of the thermosyphon in its steam zone, a heat exchanger 6 is made, the working tag of which may be water, air, etc., and inside the thermosyphon there is a deflector perforated in the lower part. 7

Works submerged lance as follows.

When the housing 1 with the tip 2 is immersed in the bath of molten metal to carry out a purge heat carrier filling the capillary porous material 3 (Na is used as the heat carrier or Na-K eutectic with the ratio

TG | гу gu) is evaporated; selection tepK pU

from the heated wall of housing 1, and condenses in section 5 of the housing recessed into the thermosyphon 4, giving out the latent heat of vaporization to the secondary circuit, cooling coil to the thermosyphon. Under the influence of heat transferred by a heat transfer fluid in the capillary-porous material 3 located in housing 1 , the heat carrier of thermosyphon A is heated and boiled. Thermosyphon heat carrier vapors k fill its vapor cavity and condense on the inner wall.

thermosyphon in the area of the heat exchanger 6,

i.

Condensate formed under the action of gravitational forces flows along the wall into a thermosyphon zone filled with liquid. At any heat flux from the lance body 1 to the heat transfer filling the lower part of the thermosyphon C, its temperature remains at the necessary-high level. (Ensuring the heat pipe 1 works optimally. Short-time change of the heat-exchange mode in the area of the tip 2 and at By constant flow of the coolant through the heat exchanger, the intensity of the boiling point of the coolant in section 5 slightly increases or the vapor pressure in the vapor zone decreases.

siphon i.

When the working fluid in the thermosyphon boils, the resulting bubbles float along the gap between its heat-supplying wall and deflector 7 of the heat transfer medium to the space vacated by the bubble through perforations in the deflector, which intensifies the heat exchange between the heat pipe of the lance 1 and the thermo junction 1y k.

Such a constructive implementation of the tuyere improves its durability.

Claims (2)

1. USSR author's certificate number tlOOg, cl. C 21B 7/16, 1971.. 2. Authors1 th USSR certificate tP, cl. C 21 C 5L8, 1968 (prototype).