JPH052724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) In order to compensate for the heat source of blowing in a reaction vessel for metal smelting, such as a bottom blowing converter or similar smelting ladle, Although it is useful to direct a flame toward the contents of the reactor vessel by contacting the pneumatic feed stream with a surrounding oxygen stream within the reactor vessel, in connection with such combustion lances, this specification includes: The following describes the results of research and development to improve the durability of the lance while simplifying the structure.

(Prior art) Regarding a refining/combustion lance in a reaction vessel for metal refining, Japanese Patent Application Laid-open No. 144409/1983 describes that fine carbon powder as a carbonaceous powder is passed through the center passage of the lance.
It has been disclosed that oxygen gas is injected from peripheral passages, but this requires a cooling fluid passage surrounding the central passage, which complicates the structure and poses a problem in durability.

(Problems to be Solved by the Invention) The charge in a reaction vessel for metal refining is exposed to flame by contact between a pneumatic feed stream of carbonaceous powder material and an oxygen stream surrounding it. The purpose of this invention is to improve the durability of a combustion lance used to assist in the refining of raw materials while simplifying the structure. This is intended to contribute to improving production efficiency.

(Means for Solving the Problems) The present invention provides a pneumatic supply flow of carbonaceous powder material and an oxygen gas flow surrounding the pneumatic supply flow from above a reaction vessel for metal refining toward a charge in the reaction vessel. A combustion lance for smelting and combustion, characterized in that the nozzle that controls the pneumatic supply of carbonaceous powder material has a lining of heat-resistant and wear-resistant ceramic refractory material. It's Lance.

The inventors studied various materials and structures for the carbonaceous powder injection flow path in the lance, and found that the nozzle of the flow path has a lining made of a ceramic refractory material with excellent heat resistance and wear resistance. As a result, we have found the following advantages:

(1) Nozzle cooling is not required and the lance structure can be simplified; (2) nozzle wear resistance is improved and lance durability is improved; It is also possible to detect wear and tear by installing a thermocouple that is useful for detecting wear and tear.

Now, FIG. 1 shows a cross section of a refining/combustion lance according to the present invention.

1 in the figure is a flow path for carbonaceous powder material, and in order to avoid combustion or explosion in the pipes including this flow path 1, reaction with inert gas or carbon in the substance is usually difficult to occur. A pneumatic feed stream is introduced with a non-oxidizing gas as the carrier gas.

2 is heat resistant, which is provided so that the flow path 1 of the carbonaceous powder material is protected from abrasion and frictional heat due to contact with the material or the high temperature atmosphere in the reaction vessel;
The lining is made of ceramic refractory material with excellent wear resistance. The ceramic refractory material includes BC,
WC, TiC, Al ₂ O ₃ , ZrO ₂ , SiO ₂ , SiC, etc. are used.

Reference numeral 3 designates a flow path piping for carbonaceous powder material, and since the outer peripheral surface is in contact with oxygen gas, stainless steel pipes or copper pipes that can withstand even an oxidizing atmosphere are used.

Reference numeral 4 denotes a thermocouple that measures the temperature of the mouthpiece 5 that serves as the spout of the carbonaceous powder material from the flow path 1, and the lead wire of this thermocouple is exposed when a hole is formed in the lining 2 due to wear. This can be used to detect holes in the lining, quickly detect abnormalities in the lance, and prevent damage to the lance and major accidents. The thermocouple 4 is wound around the outer peripheral surface of the lining 2 or installed along the longitudinal direction of the lining 2 to ensure good contact between the tip 4' of the thermocouple 4 and the mouthpiece 5.
Accurately measure the temperature of

The lining 2, flow path piping 3, and mouthpiece 5 constitute a nozzle 6 that controls pneumatic supply of carbonaceous powder material.

In addition, since the mouthpiece 5 is the tip of the nozzle 6 and is exposed to the highest temperature and oxidizing atmosphere, it is made of heat-resistant, non-oxidizing materials such as Al ₂ O ₃ , SiO ₂ , and ZrO _{2 .}
Use ceramic fireproof materials such as

Reference numeral 7 designates a carbon gas flow path for combustion of carbonaceous powder material, in which the mouthpiece 5 at the tip of the nozzle 6 directs the blowing direction of oxygen gas so that it collides with the pneumatic supply flow of carbonaceous powder material, and carbon Increases the combustibility of powdery substances. The optimum angle of intersection between the center lines of the oxygen gas flow and the pneumatic supply flow of the carbonaceous powder material varies depending on the volatile content ratio in the carbonaceous powder material and the ejection speed.
Fits in the range of 30-75 degrees.

Reference numeral 8 denotes a cooling fluid flow path in the lance outer cylinder and tip, which is essential for improving the durability of the lance used in a high-temperature reaction vessel.

(Function) A non-oxidizing substance is used for the flow path piping of the nozzle, and a heat-resistant and abrasion-resistant ceramic refractory material is used for the inner lining of the flow path piping. Furthermore, it is possible to extend the life of the lance and simplify the structure.

(Example) Refining was carried out using the equipment shown in Figure 2, which is equipped with a 5-ton converter as a reaction vessel capable of bottom-blowing oxygen gas together with a combustion lance.

In Figure 2, 9 is a refining/combustion lance, 10 is a top-bottom blowing converter, 11 is a bottom-blowing tuyere that supplies oxygen and propane for cooling the tuyere, 12 is charged hot metal, 1
3 is a dispenser for storing carbonaceous powder material (pulverized coal) and transporting gas, and 14 is a dispenser for powdered chromium ore.

The structure of the combustion lance 8 is as shown in Fig. 1 above, and a stainless steel tube is used for the flow path piping, and a Pt tube for measuring the temperature of the mouthpiece is attached to the inner periphery of the tube.
A thermocouple of -Pt13wt%Rh was wrapped around it, and a 3.5mm thick pipe made of high alumina sintered body was fixed with adhesive as a lining, and a high alumina sintered body was also used for the mouthpiece.

The operating procedure is to first preheat the inside of the converter sufficiently to bring the temperature of the inner wall of the furnace to approximately 900°C, and then heat the molten metal at approximately 1250°C.
4.5 tons were charged.

Next, set the furnace vertically and introduce oxygen through the bottom tuyere 10.
7.5Nm ³ /min and propane gas for tuyere cooling.
0.45Nm ³ /min was supplied. At the same time, the combustion lance 9 is lowered from above the furnace, and 35 kg/min of pulverized coal and 17.5 Nm ³ /min of oxygen are supplied as carbonaceous powder, and the pulverized coal is combusted at the nozzle outlet of the lance, and the generated flame turns into hot metal. The lance 9 was fixed at the position where it hit.

After maintaining the hot metal temperature in this state until it reaches 1600℃, powdered chromium ore is supplied from the dispenser 14 at a rate of 25 kg/min for another 60 minutes to join with the pulverized coal in the middle of the piping, and then from the combustion lance 9 into the hot metal. Powdered chromium ore was added. After this, the furnace was tilted to check the degree of wear on the lance nozzle, and the hot metal was sampled.

The above experiment was conducted for a total of 102 heats, and the pulverized coal
A total of about 460 tons of powder, including 300 tons and 160 tons of chromium ore, were added into the furnace through a combustion lance, but no effect was observed on the nozzle or mouthpiece of the lance.

In addition, in order to investigate the wear amount of the lining, the lining was removed from the nozzle and its weight was measured every 10 heats. The solid line in FIG. 3 shows the relationship between the rate of change, that is, the cotton floss rate and the amount of powder used.

From Figure 3, it can be seen that the lining hardly wears out when passing about 72,500 kg of powder.

Furthermore, as a result of temperature measurement of the mouthpiece during operation, the maximum temperature near the nozzle tip was 1650℃, and the melting point of the high alumina sintered body was 2030℃, indicating that it has sufficient durability. No change was observed in the nozzle observation results after operation.

Comparative example A total of 60 samples were prepared using the same method and equipment as in the example.
He operated a heat. However, the combustion lance does not have a lining and uses a stainless steel pipe as a flow path.
The mouthpiece is also made of stainless steel.

In other words, pulverized coal 35Kg/
After supplying 17.5Nm ³ /min of oxygen gas to the iron bath in the converter and raising the temperature of the iron bath to 1600℃, approximately 165 tons of pulverized coal was added at a rate of 25Kg/min of powdered chromium ore,
Approximately 95 tons of powdered chromium ore, totaling approximately 260 tons of powder, was passed through the stainless steel tube channel in the lance.

In order to compare the relationship between the wear rate of the powder flow path and the amount of powder passing through at this time with the example, it is shown by a broken line in FIG. From FIG. 3, it can be seen that the comparative example had a higher wear rate than the example because no wear-resistant lining was used. It was also confirmed that the mouthpiece partially melted in nine of the total heats.

(Effects of the Invention) In the present invention, since the nozzle of the lance is provided with a lining made of a ceramic refractory material with excellent heat resistance and wear resistance, no cooling fluid for the nozzle is required, and the structure of the lance can be simplified.

Furthermore, by arranging a thermocouple along the inner periphery of the nozzle facing the back surface of the lining, it is possible to measure the temperature at the tip of the nozzle, and also to detect holes in the lining due to wear.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the lance, FIG. 2 is an explanatory diagram of the refining equipment, and FIG. 3 is a graph showing the relationship between the wear rate and the amount of powder passing through. 1... Channel, 2... Lining, 3... Channel piping, 4... Thermocouple, 6... Nozzle.

Claims (1)

[Scope of Claims] 1. In a combustion lance that emits a flame toward a charge in a metal refining reaction vessel through contact between a pneumatic feed stream of carbonaceous powder material and an oxygen stream surrounding it. A lance for refining and combustion, characterized in that a nozzle for pneumatically supplying carbonaceous powder material has a lining of a heat-resistant and wear-resistant ceramic refractory material. 2. The lance according to claim 1, comprising a thermocouple arranged along the inner periphery of the nozzle and facing the back surface of the lining.