SU1225866A1 - Method of regulating chemical and heat treatment of steel articles - Google Patents

Description

The invention relates to chemical heat treatment and can be used in mechanical engineering, mainly in diffusion saturation of the surface of steel products with carbon in furnaces for chemical heat treatment with controlled atmospheres.

The purpose of the invention is the increase in ca2CO 2C- + O, ffpe

(3)

Therefore, the reaction rate (O and (2), which is sufficiently small, can be used to form a carbon potential within the real kiln space,

For example, after 2 h degree

and

 / Рсн4 with this post n15

20

The conversion of methane in the absence of product quality due to the increase in the point of the catalytic converter is 68.2% at 950 ° C for controlling the carbon potential along the length of the furnace.

Figure 1 is a diagram of the gas supply to the cementation furnace, with which the method is implemented; FIG. 2 shows the distribution of the carbon potential along the length, where the coordinate X corresponds to the maximum of the profile of the carbon potential.

The cementing kiln 1 for implementing the proposed method has a gas mixture inlet system 2 placed at the end of the furnace and a gas discharge system 3 placed on the loading side of the workpieces 4. The gas mixture is prepared in the mixer 5 and fed to the furnace through the flow controller 6. The furnace atmosphere is analyzed by a gas analyzing device. 7, made multipoint on the basis of oxygen potential sensors,

The essence of the method is based on the fact that the time required by dp of the reacted reaction rate is equal to 0.0034 h,

In practice, the constant reaction rate is determined by the catalytic effect of the masonry material of the furnace, the internal structures of the furnace and the material of the workpiece. The mixture of carrier gas (for example, endogas) and gas-carburizer (for example, natural gas) is supplied to the movement of parts by injecting it at the end of the furnace and releasing it first, while at the gas inlet point at the beginning of the reaction the carbon potential is at- 25 of the atmosphere is determined by the potential of the carrier gas. As the gas moves in the furnace space, reactions (1) and (2) occur, which leads to an increase in the carbon potential (from the furnace end) to a maximum in the saturation zone. A further decrease in the carbon potential to the beginning of the furnace is determined by a significant supply of oxygen to the furnace at the moments of loading.

thirty

nor the reactions forming the profile of the coal; 5 Details.

of the lateral potential in the grouting furnace, commensurate with the residence time of gas in the furnace,

In the endothermic atmosphere (carrier gas + gas-carburizer), after its heating in a furnace, complex physicochemical transformations take place, including the reaction of the furnace atmosphere with an oxidizer coming from the furnace openings when parts are loaded, damage to the radiation tubes, and so on, etc. mainly interaction. carrier gas with carburizing gas for conversion reactions:

+

+ co.

co + sign

: 2CO + 2H,

(12)

In this case, the main carrier of the coal is 55,

the type entering the parts is an example. Steel products - carbon monoxide and cementation. Gears made of steel 20ХНР, are subjected to a carburizing reaction in a non-snuffing unit.

2CO 2C- + O, ffpe

(3)

Therefore, the reaction rate (O and (2), which is sufficiently small, can be used to form a carbon potential within the real kiln space,

For example, after 2 h degree

and

 / Рсн4 with this post n5

0

methane conversion in the absence of a catalyst is 68.2% at 950 ° C

at the reaction rate is equal to 0.0034 h,

In practice, the constant reaction rate is determined by the catalytic effect of the masonry material of the furnace, the internal structures of the furnace and the material of the workpiece. The mixture of carrier gas (for example, endogas) and gas-carburizer (for example, natural gas) is supplied to the movement of parts by injecting it at the end of the furnace and releasing it first, while at the gas inlet point at the beginning of the reaction the carbon potential is at- 5 of the atmosphere is determined by the potential of the carrier gas. As the gas moves in the furnace space, reactions (1) and (2) occur, which leads to an increase in the carbon potential (from the furnace end) to a maximum in the saturation zone. A further decrease in the carbon potential to the beginning of the furnace is determined by a significant supply of oxygen to the furnace at the moments of loading.

0

An increase in the flow rate of the mixture at the same reaction rate (1) and (2) makes it possible to shift the maximum of the carbon potential towards the beginning of the furnace, and the decrease in consumption towards the end of the furnace.

The change in the rate of reactions (1) and (2) that takes place in the furnace is compensated by the change in the total flow rate of the gas mixture,

Thus, supplying the gas mixture with a single stream opposing the movement of the workpieces allows an optimal profile of the carbon potential for any process to be achieved by adjusting the position of its maximum by changing the speed or flow rate of the gas flow in the furnace.

The method is as follows.

3

0811, whose grouting furnace has a length of 10.36 m and an internal cross section of 2.5 m.

The gas flow along the length of the furnace 1 is directed against the moving parts 4 by introducing a mixture of endogas with a dew point of OH and methane in the ratio. 40: 1 at the end of the furnace and output it at the beginning. This ratio of the gas mixture is selected from the conditions for ensuring the carbon potential specified by the technology at the point of its maximum value (according to the results of the gas analysis). Endogas dew point is selected for a given carbon potential at the end of the furnace.

After heating the furnace to 920-930 C and bringing it to the mode, the gas-analyzing device 7 is turned on, which, according to the result of the analysis of the sample at several points of the furnace, gives information about the position of the maximum of the carbon potential (X coordinate). If the position of this maximum turns out - gas

Zone disfuz1 and

Saturated area

Editor N. Gunko

Compiled by T.Naumova Tehred V.Kadar

Order 2103/19 Circulation 552Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Design, 4.

258664

with the offset from the given technology depending on the workpiece to the end of the furnace, the flow rate of the mixture is increased by the regulator 6

5 flow rate, maintaining, by mixer 5, the previously selected ratio of carrier gas and gas carburizer, until the position of the X coordinate specified by the technology is restored.

10 position of the maximum carbon potential to the beginning of the furnace gas consumption is reduced.

The use of the proposed method allows to improve the quality of the product with LIU by reducing the deviations of the values of the carbon potential of the atmosphere from its specified profile in the furnace to 0.05%. The shift of the maximum profile of the carbon potential

2Q to the length of the furnace does not exceed ± 0.1 m, which is 4-5 times greater than the accuracy of maintaining the position of the maximum as compared with the zone-to-zone regulation of the process of chemical-thermal treatment of products.

Active heating zone

Ovens

Fi & .g

Proofreader E. Sirohmai

Claims (1)

METHOD FOR REGULATING THE CHEMICAL AND THERMAL PROCESSING PROCESS STEEL PRODUCTS, consisting of a boom in a cement kiln, selecting the ratio of the flow rates of these gases to obtain a given value of the carbon potential, forming a carbon potential profile with a maximum value in the saturation zone, monitoring the carbon potential along the length of the furnace, characterized in that, in order to improve the quality of products by increasing the accuracy of regulating the carbon potential along the length of the furnace, a mixture of carrier gas. and the gas-carburizer are directed in a single flow in the opposite direction to the movement of the workpieces and maintain the maximum carbon potential of the atmosphere at a point specified by the technology by controlling the flow rate of the mixture while maintaining the selected ratio of the mixture of carrier gas and karium gas.