CN102226226A - Method for preventing mushroom head blockage in converter steel making process - Google Patents

Abstract

The invention relates to a method for preventing mushroom head blockage in a converter steel making process, belonging to the technical field of metallurgy and steel making. The method is implemented by mounting a stainless steel tube at the center of a circumferential seam in a bottom lance and introducing oxygen; a thermocouple is arranged between the stainless steel tube and the circumferential seam so as to measure the temperature of the bottom lance; the lower the temperature of the bottom lance is, the smaller the quantity of gas blown from the bottom is, which indicates that as the formed mushroom head becomes bigger, more oxygen can be introduced to reduce the volume of the mushroom head; and if the formed mushroom head becomes smaller, less oxygen can be introduced, so that the mushroom head on the bottom lance can be kept at proper dimension. The stainless steel tube is mounted at the center of the circumferential seam of the bottom lance so as to introduce oxygen, and the exothermic reaction between the oxygen and the mushroom head solidified steel enables the mushroom head to melt; and the method is simple and has good application effect.

Description

A kind of converter steelmaking method that head stops up that prevents to pester

Technical field

The present invention relates to metallurgical steelmaking technical field, a kind of converter steelmaking method that head stops up that prevents to pester.

Background technology

It is strong that the steel-making converter top and bottom complex blowing has stirring capacity, and finishing slag (FeO) content is low, and iron loss is low, yield of alloy height, advantage such as tap to tap time is short.But end rifle is abominable in steel-making converter bottom working conditions, and molten steel easily forms the mushroom head above the end rifle, stops up end rifle, causes the bottom blown gas amount to reduce, and stops up end rifle fully when serious, makes the bottom blown gas amount be reduced to zero.How solving end rifle blockage problem is the gordian technique of steel-making converter bottom blown gas.

Summary of the invention

The purpose of this invention is to provide a kind of converter steelmaking method that head stops up that prevents to pester, this method is coagulated the thermopositive reaction that steel takes place by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end by oxygen and mushroom head, makes the mushroom first meltization; Method is simple, and result of use is good.

For achieving the above object, the present invention is achieved through the following technical solutions:

A kind of converter steelmaking method that head stops up that prevents to pester, this method realizes by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end, the thermopair of packing between stainless steel tube and circumferential weld is measured end rifle temperature, end rifle temperature is low, the bottom blown gas amount is few, illustrate that the mushroom head that forms is big, then increase the oxygen flow that feeds and reduce a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size.

A kind of converter steelmaking method that head stops up that prevents to pester, this method realizes by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end, the thermopair of packing between stainless steel tube and circumferential weld is measured end rifle temperature, according to the calculation result of end rifle air feed and mathematical Model of Heat Transfer, regulate the oxygen flow that the center stainless steel tube feeds by the PLC Controlling System; End rifle temperature is low, and the bottom blown gas amount is few, illustrates that the mushroom head that forms is big, then increases the oxygen flow that feeds and reduces a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size;

Described mathematical Model of Heat Transfer is according to heat transfer theory, and the dynamic tracking by micro unit realizes, adopts Visual C++6.0 to write, and uses the Access database to store;

1) model hypothesis condition

Radially heat transfer ratio axial heat conduction is much smaller for the steel-making converter furnace bottom, so can ignore along the heat transfer of x, y direction; If long is dx, wide is dy, and height is converter bottom refractory or the steel plate micro unit of dz, sets up the differential equation according to heat transfer theory:

${\mathrm{\ρc}}_p\frac{\∂T}{\∂t}=\frac{\∂}{\∂Z}\left(\mathrm{\λ}\frac{\∂T}{\∂Z}\right)$

In the formula: ρ-density, kg/m ³

The T-temperature, ℃;

The t-time, s;

c _p-specific heat, J/kg ℃;

λ-thermal conductivity, W/m ℃;

The Z-radial distance, m;

Be reduced equation and final condition thereof, carry out following hypothesis:

(1) the converter molten steel temperature is even, and is the linear function of time.

(2) surface temperature is identical with the converter molten steel temperature on the steel-making converter furnace bottom;

(3) density of bottom refractory and steel plate of furnace hearth is considered as constant;

(4) conducting heat between bottom refractory and steel plate of furnace hearth is heat transfer by conduction;

(5) conducting heat between steel plate of furnace hearth and atmosphere is convection current and radiative transfer;

2) starting condition and final condition

Starting condition:

During t=0, the temperature of bottom refractory and steel plate of furnace hearth is a linear distribution, that is: surface temperature equals to be blended into the molten iron temperature of converter for the highest on the bottom refractory; The steel plate of furnace hearth temperature of lower is minimum, is the actual temperature outside the steel-making converter steel plate of furnace hearth of measuring;

Final condition:

Steel-making converter furnace bottom upper face temperature equals the converter molten steel temperature, linear in time increase;

Conducting heat between steel-making converter steel plate of furnace hearth lower surface and atmosphere is convection current and radiative transfer, and free air temperature is the actual temperature of environment;

Q ₁＝h(T _d-T _h)+σε[(T _d+273.15) ⁴-(T _h+273.15) ⁴]

In the formula: Q ₁-steel plate and atmosphere hot-fluid, kW/m ²

Heat transfer coefficient between h-steel plate and atmosphere, kW/ (m ²℃);

T _d-converter steel plate of furnace hearth temperature outside, ℃;

T _h-atmospheric environment temperature, ℃;

σ-radiation coefficient;

ε-Boltzmann constant 5.67 * 10 ^-8W/ (m ²K ⁴);

3) model solution

Steel-making converter furnace bottom heat transfer process is a unsettled conduction process, adopts numerical solution; The essence of numerical method is to make a continuum discretize, replace partial differential equation with a series of algebraic equations, by calculating the numerical solution that obtains steel-making converter bottom temperature field, can obtain the temperature distribution of converter bottom refractory and steel plate, comprising the temperature at the thermocouple location place of measuring end rifle temperature;

4) converter bottom gas supply control

The difference between the temperature that the oxygen-supplying amount of converter bottom blowing calculates according to the temperature field of the steel-making converter bottom temperature of actual measurement and corresponding position and the gas volume of converter bottom blowing are regulated control; Difference is big, and oxygen-supplying amount increases, otherwise reduces.

Compared with prior art, the invention has the beneficial effects as follows:

This method is coagulated the thermopositive reaction that steel takes place by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end by oxygen and mushroom head, makes the mushroom first meltization; Method is simple, and result of use is good.

Description of drawings

Fig. 1 is steel-making converter bottom construction figure of the present invention.

Among the figure: the stainless steel tube 4-thermopair of the circumferential weld 3-circumferential weld center aerating oxygen of 1-converter bottom refractory 2-converter bottom blown gas (nitrogen, argon gas or carbonic acid gas)

Embodiment

Embodiment 1

A kind of converter steelmaking method that head stops up that prevents to pester, this method realizes by stainless steel tube 3 aerating oxygens of packing at rifle circumferential weld 2 centers, 1 end of converter bottom refractory, the thermopair 4 of packing between stainless steel tube 3 and circumferential weld 2 is measured end rifle temperature, end rifle temperature is low, the bottom blown gas amount is few, illustrate that the mushroom head that forms is big, then increase the oxygen flow that feeds and reduce a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size.

Embodiment 2

A kind of converter steelmaking method that head stops up that prevents to pester, this method realizes by stainless steel tube 3 aerating oxygens of packing at rifle circumferential weld 2 centers, 1 end of converter bottom refractory, the thermopair 4 of packing between stainless steel tube 3 and circumferential weld 2 is measured end rifle temperature, according to the calculation result of end rifle air feed and mathematical Model of Heat Transfer, regulate the oxygen flow that the center stainless steel tube feeds by the PLC Controlling System; End rifle temperature is low, and the bottom blown gas amount is few, illustrates that the mushroom head that forms is big, then increases the oxygen flow that feeds and reduces a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size;

Described mathematical Model of Heat Transfer is according to heat transfer theory, and the dynamic tracking by micro unit realizes, adopts Visual C++6.0 to write, and uses the Access database to store;

1) model hypothesis condition

Radially heat transfer ratio axial heat conduction is much smaller for the steel-making converter furnace bottom, so can ignore along the heat transfer of x, y direction; If long is dx, wide is dy, and height is converter bottom refractory or the steel plate micro unit of dz, sets up the differential equation according to heat transfer theory:

${\mathrm{\ρc}}_p\frac{\∂T}{\∂t}=\frac{\∂}{\∂Z}\left(\mathrm{\λ}\frac{\∂T}{\∂Z}\right)$

In the formula: ρ-density, kg/m ³

The T-temperature, ℃;

The t-time, s;

c _p-specific heat, J/kg ℃;

λ-thermal conductivity, W/m ℃;

The Z-radial distance, m;

Be reduced equation and final condition thereof, carry out following hypothesis:

(1) the converter molten steel temperature is even, and is the linear function of time.

(2) surface temperature is identical with the converter molten steel temperature on the steel-making converter furnace bottom;

(3) density of bottom refractory and steel plate of furnace hearth is considered as constant;

(4) conducting heat between bottom refractory and steel plate of furnace hearth is heat transfer by conduction;

(5) conducting heat between steel plate of furnace hearth and atmosphere is convection current and radiative transfer;

2) starting condition and final condition

Starting condition:

During t=0, the temperature of bottom refractory and steel plate of furnace hearth is a linear distribution, that is: surface temperature equals to be blended into the molten iron temperature of converter for the highest on the bottom refractory; The steel plate of furnace hearth temperature of lower is minimum, is the actual temperature outside the steel-making converter steel plate of furnace hearth of measuring;

Final condition:

Steel-making converter furnace bottom upper face temperature equals the converter molten steel temperature, linear in time increase;

Conducting heat between steel-making converter steel plate of furnace hearth lower surface and atmosphere is convection current and radiative transfer, and free air temperature is the actual temperature of environment;

Q ₁＝h(T _d-T _h)+σε[(T _d+273.15) ⁴-(T _h+273.15) ⁴]

In the formula: Q ₁-steel plate and atmosphere hot-fluid, kW/m ²

Heat transfer coefficient between h-steel plate and atmosphere, kW/ (m ²℃);

T _d-converter steel plate of furnace hearth temperature outside, ℃;

T _h-atmospheric environment temperature, ℃;

σ-radiation coefficient;

ε-Boltzmann constant 5.67 * 10 ^-8W/ (m ²K ⁴);

3) model solution

Steel-making converter furnace bottom heat transfer process is a unsettled conduction process, adopts numerical solution; The essence of numerical method is to make a continuum discretize, replace partial differential equation with a series of algebraic equations, by calculating the numerical solution that obtains steel-making converter bottom temperature field, can obtain the temperature distribution of converter bottom refractory and steel plate, comprising the temperature at the thermocouple location place of measuring end rifle temperature;

4) converter bottom gas supply control

The difference between the temperature that the oxygen-supplying amount of converter bottom blowing calculates according to the temperature field of the steel-making converter bottom temperature of actual measurement and corresponding position and the gas volume of converter bottom blowing are regulated control; Difference is big, and oxygen-supplying amount increases, otherwise reduces.

Claims (2)

1. the converter steelmaking method that head stops up that prevents to pester, it is characterized in that, this method realizes by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end, the thermopair of packing between stainless steel tube and circumferential weld is measured end rifle temperature, end rifle temperature is low, the bottom blown gas amount is few, illustrates that the mushroom head that forms is big, then increases the oxygen flow that feeds and reduces a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size.

2. the converter steelmaking method that head stops up that prevents to pester, it is characterized in that, this method realizes by the stainless steel tube aerating oxygen of packing at rifle circumferential weld center, the end, the thermopair of packing between stainless steel tube and circumferential weld is measured end rifle temperature, according to the calculation result of end rifle air feed and mathematical Model of Heat Transfer, regulate the oxygen flow that the center stainless steel tube feeds by the PLC Controlling System; End rifle temperature is low, and the bottom blown gas amount is few, illustrates that the mushroom head that forms is big, then increases the oxygen flow that feeds and reduces a mushroom volume; Otherwise reduce the oxygen flow that feeds, make the mushroom head above the end rifle remain on suitable size;

Described mathematical Model of Heat Transfer is according to heat transfer theory, and the dynamic tracking by micro unit realizes, adopts Visual C++6.0 to write, and uses the Access database to store;

1) model hypothesis condition

Radially heat transfer ratio axial heat conduction is much smaller for the steel-making converter furnace bottom, so can ignore along the heat transfer of x, y direction; If long is dx, wide is dy, and height is converter bottom refractory or the steel plate micro unit of dz, sets up the differential equation according to heat transfer theory:

${\mathrm{\ρc}}_p\frac{\∂T}{\∂t}=\frac{\∂}{\∂Z}\left(\mathrm{\λ}\frac{\∂T}{\∂Z}\right)$

In the formula: ρ-density, kg/m ³

The T-temperature, ℃;

The t-time, s;

c _p-specific heat, J/kg ℃;

λ-thermal conductivity, W/m ℃;

The Z-radial distance, m;

Be reduced equation and final condition thereof, carry out following hypothesis:

(1) the converter molten steel temperature is even, and is the linear function of time.

(2) surface temperature is identical with the converter molten steel temperature on the steel-making converter furnace bottom;

(3) density of bottom refractory and steel plate of furnace hearth is considered as constant;

(4) conducting heat between bottom refractory and steel plate of furnace hearth is heat transfer by conduction;

(5) conducting heat between steel plate of furnace hearth and atmosphere is convection current and radiative transfer;

2) starting condition and final condition

Starting condition:

During t=0, the temperature of bottom refractory and steel plate of furnace hearth is a linear distribution, that is: surface temperature equals to be blended into the molten iron temperature of converter for the highest on the bottom refractory; The steel plate of furnace hearth temperature of lower is minimum, is the actual temperature outside the steel-making converter steel plate of furnace hearth of measuring;

Final condition:

Steel-making converter furnace bottom upper face temperature equals the converter molten steel temperature, linear in time increase;

Conducting heat between steel-making converter steel plate of furnace hearth lower surface and atmosphere is convection current and radiative transfer, and free air temperature is the actual temperature of environment;

Q ₁＝h(T _d-T _h)+σε[(T _d+273.15) ⁴-(T _h+273.15) ⁴]

In the formula: Q ₁-steel plate and atmosphere hot-fluid, kW/m ²

Heat transfer coefficient between h-steel plate and atmosphere, kW/ (m ²℃);

T _d-converter steel plate of furnace hearth temperature outside, ℃;

T _h-atmospheric environment temperature, ℃;

σ-radiation coefficient;

ε-Boltzmann constant 5.67 * 10 ^-8W/ (m ²K ⁴);

3) model solution

Steel-making converter furnace bottom heat transfer process is a unsettled conduction process, adopts numerical solution; The essence of numerical method is to make a continuum discretize, replace partial differential equation with a series of algebraic equations, by calculating the numerical solution that obtains steel-making converter bottom temperature field, can obtain the temperature distribution of converter bottom refractory and steel plate, comprising the temperature at the thermocouple location place of measuring end rifle temperature;

4) converter bottom gas supply control

The difference between the temperature that the oxygen-supplying amount of converter bottom blowing calculates according to the temperature field of the steel-making converter bottom temperature of actual measurement and corresponding position and the gas volume of converter bottom blowing are regulated control; Difference is big, and oxygen-supplying amount increases, otherwise reduces.

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