SU1375665A1 - System for obtaining controlled atmosphere for heat-treating furnace - Google Patents

Abstract

The invention relates to the heat treatment of products in a controlled atmosphere and can be used in cleaning processes in heat treatment furnaces, mainly through passage. The purpose of the invention is to prevent the surface of heat-treated products from oxidizing with free oxygen during the cooling process and to reduce the flow of protective gas to neutralize the air drawn into cold zones. furnaces due to the full use of the protective gas reduction possibilities. The essence of the invention is that the heated shielding gas withdrawn from the jet cooling chamber 5 is cooled in the refrigerator 10 and then by the fan 11 through the pipeline 9 is fed simultaneously to the chamber 5 through the nozzle 7 and through the actuator 15 to the cleaning unit 12. The amount of gas supplied to purification unit 12 is regulated depending on the oxygen content in the protective gas of chamber 5, measured by sensor 14, which should not exceed 0.001-0.05 vol%, which is set on the setpoint of regulator 13 "Remaining recirculation Protective gas is supplied to chamber 5. Purified gas from purification unit 12 is mixed with protective gas withdrawn from chamber 5 through nozzle 6, cooled in refrigerator 10 and fan P is again pumped to chamber 5 and purification unit 12 1 il i (L about joint O) O) ate

Description

The invention relates to heat treatment in a controlled atmosphere of products made of iron-based and copper-based alloys and can be used when carrying out annealing processes in heat-treatment furnaces, mainly through-passing, in particular, during annealing of rolled products in passing-through furnaces with jet cooling areas. providing intensive cooling of heat-treated steel by shielding gas recirculation

The aim of the invention is to prevent the oxidation of the surface of heat treated products with free oxygen during the cooling process and to reduce the flow of protective gas by. Neutralization of the aspirated air into the cold zones of the furnace due to the full use of the reducing potential of the protective gas.

The drawing shows the proposed

respectively to the suction 6 and injection 7 nozzles - cooling chambers

A conduit 22 connects the sensors 14, 20 and 21 to the kiln-jet cooling chamber 5.

The device works as follows

From the blast chiller 5, the heated shielding gas is cooled in the refrigerator 10 and then supplied by the fan 11 via pipeline 9 to the chamber 5 through the nozzle 7 and through the actuator 15 to the cleaning unit 12 at the same time.

The amount of gas supplied to purification unit 12 is regulated depending on the oxygen content in the protective gas of the jet cooling chamber 5, which should not exceed 0.001-0.005% vol.%, Which is set accordingly at the setting point of the regulator 13o.

arrangement of

The continuous furnace includes a heating chamber 1, loading locks 2 and unloading 3, a water-cooled section 4, a jet cooling chamber 5 with

suction nozzle 6 and 30-ke supercharger 10 and fan 1 again

with a suction 8 and injection 9 pipelines connected to a cooler 10, a fan 11, a cleaning unit 12 and a regulator 13 of the amount of gas supplied to the cleaning

The regulator 13 operates in combination with an oxygen content sensor 14 for determining the oxygen content in the protective gas in chamber 5 and with the regulator 15 installed in the area of the discharge pipe 9 in front of the cleaning unit 12.

The suction pipe 8 is connected to the feed pipe 16 with fresh protective gas supplied with a regulator 17 connected to the output of the regulator 18, the inlet of which is connected to the outlet of the ratio unit 19, the inlet of which is connected to the sensor 20 for changing the content of H, 0 and the sensor 21 for measuring the content of I20 in the protective gas of the cooling chamber 5

The cleaning unit 12, which is supplied with a regulated regulation of the amount of gas supplied by the fan 13, is installed in front of the cooler 10 between the suction side 1, 8 of them and 9 injection pipes connected to the supply of protective gas.

In order to fully utilize the reduction potential of the gas of the rest, the capacity of the cleaning gas unit is fed into chamber 5.

The purified gas from the cleaning unit is then mixed with the protective gas taken from chamber 5 through pipe 6 and cooled in a fridge.

0

melts into the chamber 5 and the cleaning unit 12,

A fresh shielding gas is continuously supplied through the conduit 16 to the circulation circuit, the amount of which is automatically controlled depending on the HQ

ratios (

H, 0

)

in protective at0

jet-spray chamber 5

The amount of protective gas per make-up should be sufficient to maintain a ratio in the jet cooling chamber 5

(-rp) S protective atmosphere in the zone

Uuj

recovery for the material being processed

Depending on the given ratio of the received data on

 H, the ratio of g .-- in chamber 5 from sensor jU

20 and 21 and the ratio block 19, the regulator 18 supplies a pulse to the regulator 17 for the protective gas corresponding to the make-up.

In order to fully utilize the reduction potential of the gas of the target, the capacity of the cleaning unit is set according to an equation based on experimental data.

 0.5 U, p (q;)

1o 00 -0 00511ts + ij

where V is block performance

cleaning, MV4; V 1 p - the volume of the circuit recirculated -

tion, m;

H 2 - the hydrogen content in the original protective gas, vol.%;

H,; 0 - the content of water vapor in the original protective gas, OBL;

K is the ratio of hydrogen to water vapor in shielding gas, providing protection against oxidation of the material being processed.

The permissible rate of flow of oxygen into the cooling chamber is determined from the equation

H, - K p

2Tk; + iT

(2)

where Oj is the permissible rate of flow of oxygen,% / h; H is the hydrogen content in the original protective gas, vol,%; the water vapor content in the initial shielding gas,% K, is the minimum ratio H / H jO in the protective gas of the cooling chamber, which provides protection against oxidation. When the rate of oxygen leaks is more acceptable, to prevent oxidation, the hydrogen content. In the protective gas of the cooling chamber, according to the formula (2) o When the flow rate of oxygen into the cooling chamber is less than permissible - it is possible to reduce the hydrogen content in the protective gas and reduce its supply to the jet cooling section

 In the process of purification from oxygen, the change in the ratio of hydrogen to water vapor in the protective atmosphere of the cooling chamber is determined by the ratio

H - 20;

,

five

five

five

0

where Oj is the amount of oxygen flowing into the cooling chamber,% / h.

The make-up of the cleaning device with fresh protective gas should be arranged so that the indicated ratio does not leave the recovery zone for the material of the heat treated products during their cooling.

The presence of a regulator in the purification unit makes it possible to optimize the amount of gas supplied to the purification in order to maintain the 02 content in the given values. the limits ensuring the prevention of oxidation of the cooled products - and, thereby, improve the quality of the surface, and the installation of a cleaning unit in front of the refrigerator between the suction and discharge pipes, Toe. on the bypass, it makes full use of the reduction potential of weighted gas by economically cleaning a part of the protective gas recirculating through the cooling chamber, and thereby reducing the consumption of protective gas consumed by the furnace, while improving the quality of the products being processed.

Claims (1)

Invention Formula A controlled atmosphere production system for a heat-treating furnace, containing aspirated 1Y and pressure pipes with a refrigerator and a fan between them in series, a unit for purifying oxygen from gas, characterized in that, in order to prevent free oxygen from oxidizing the surface of the heat treated products the consumption of natural gas to neutralize the air drawn into the cold zones of the furnace due to the full use of the recovery possibilities of the hectare a, it is equipped with a sensor for monitoring the oxygen content, regulating the amount of gas supplied to the purification, sensors for monitoring the hydrogen and moisture content, a ratio block, regulating the amount of supplying protective gas, actuators on the supply gas pipeline and the inlet pipeline of the purification unit, moreover, the cleaning unit is installed parallel to the refrigerator and fan, and the sensors of the controller are 1375665 The content of hydrogen and moisture is co-connected to the input of the regulator of quantification with the input of the ratio block, the gas supplied to the cleaning, the output of which is connected to the input of which is connected to the actuator of the amount of feed. At the inlet pipeline of the shielding gas, to the outlet of the cleaning unit, and the sensor inputs are connected to the executive body of the oxygen monitoring unit, the water supply pipe of the feed gas, argon and moisture are connected to the chamber with the oxygen monitoring sensor of the furnace.