DE3306973A1 - CAST IRON COMPONENT FOR COOKING OVENS - Google Patents

Description

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Cast iron component for coke ovens ■

Doors, frames and other components of coke ovens, such as flare tube closures or filling hole covers, have so far usually been made of gray cast iron (GG 25). When the furnace is in operation, these components are subject to high and fluctuating temperatures. In this case, it proves that the cast material previously used for these fluctuations and high temperatures (up to 400 ⁰ C) does not have ideal characteristics.

The drop in tensile strength, in particular, is unsatisfactory in the casting material used hitherto with greater wall thickness, the decrease in strength with increasing temperature (insufficient heat resistance) as well as the so-called. Growth stability (increase in volume with repeated high thermal stress).

With regard to these unsatisfactory mechanical properties of the cast material used hitherto iales was required in the past, when building coke ovens through constructive measures to reduce the temperature stress on the individual cast components and, if possible, to make them more uniform. For this purpose it is known, for example, between the door body and the shielding or insulating components to provide an air gap by means of spacers. Such a one However, construction requires a considerable manufacturing effort.

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On the other hand, a good dimensional stability of the door body of a coke oven is also for this reason required because the flexible sealing systems used for sealing only have a limited stroke have and a correction required in the case of a high thermal deformation of the door body the stroke is only possible through a complex adjustment of the spring elements of the sealing systems.

The invention is therefore based on the object for components that are subject to high thermal loads and which are subject to changing loads to create a cast iron of coke ovens that avoids the disadvantages described, in particular due to high strength, insensitivity to wall thickness, heat resistance, growth resistance and is characterized by high wear resistance.

This object is achieved according to the invention by means of a cast iron solved, that a purely pearlitic structure, finest graphite distribution and the following guide analysis owns:

Carbon silicon 25 manganese

Phosphorus sulfur

To stabilize the pearlitic structure, other alloy components can be added in smaller amounts Amount to be added, in particular nickel, copper, chromium, and / or molybdenum.

2.7 - 2, 9% 1/6 - 1, 8th% 0.8 - ο, 9% Max. 0.1% ' Max. 0.1%

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Depending on the carbon and manganese content, a cast iron with a tensile strength of 30 to 40 Kp / mm ^{2 is} achieved.

The material according to the invention is characterized by high strength properties, insensitivity to wall thickness, Heat resistance, growth resistance and good wear resistance.

The insensitivity to wall thickness is shown by the fact that the tensile strength (between 30 and 40 Kp / mm ^a ) remains approximately constant for wall thicknesses up to about 70 mm.

With regard to the high-temperature strength, it is important that up to temperatures of about 400 ^° C. there is no decrease in strength.

The growth resistance is also remarkable: even after annealing twelve times at 85O ⁰ C that is

Cast iron according to the invention has only grown by 2 to 3% by volume, while normal gray cast iron (GG 20) under these conditions shows an increase in volume of 8 to 10% by volume.
25th

Despite the high strengths, that is according to the invention Cast iron is easy to work with. The main mechanical and physical values are as follows:

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Flexural strength Kp / mm ² approx. 60

Deflection mm 10

Tensile strength Kp / mm ² 30.

Yield strength Kp / mm ²

Elongation% 0

Hardness HB 3000/10/20 Kp / mm ² 200 240

Modulus of elasticity Kp / mm ² (· 10 ³ ) 12 ... 13.5

Slip modulus ■ Kp / mm ² (· 10 ³ ) 5.2 ... 5.5

Impact strength m · Kp / cm ² 0.52

Bending fatigue strength Kp / mm ² + _ 12 ...

Expansion coefficient -5 - ^ - (10) 10

Specific weight kg / dm ³ 7.3

Spec. Electrical

Resistance at 20 ⁰ C (JI mm ² / m) 0.3

Thermal conductivity cal / cm ⁰ C s 0.13

Coercive Force (Oe). 12th

Remanence Br (Gauss) 5500

Magn. Saturation (Gauss) ₇

at H = 10 ⁴ (Oe) 18 * 10 "

The production of the cast iron according to the invention. preferably takes place in an induction melting furnace.

A major advantage of using the inven-

cast iron according to the invention for coke oven components consists in the fact that the above-mentioned, in the case of the known Executions required complex constructive measures to reduce or equalize the thermal load are not required. So it is when using the invention Cast iron in particular not necessary,

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To provide an air gap between the door body and the insulating part of a coke oven door in a complex manner. Due to the high growth resistance of the cast iron according to the invention, hardly any is produced Bending line of the door body. For pressing the sealing • systems, the simplest components can also be used.

Two exemplary embodiments of the invention are illustrated schematically in the drawing.

Fig.1 shows the door area of a coke oven at your the door body 1 and the door frame 2 are made of the cast iron according to the invention. Because of the . good insensitivity to wall thickness, heat resistance and growth stability of the invention Cast iron can face an air gap between the door body 1 and one of the furnace chamber 3, heat-shielding component 4 can be dispensed with; the heat-shielding component 4 is accordingly direct attached to the door body 1.

The seal between the door body 1 and the door frame 2 is done by Z-shaped sealing strips 5, which are pressed against the door frame 2 by spring elements 6 and strips 7.

With regard to the described good thermal properties of the cast iron according to the invention remain the thermally induced deformations of the door body 1 and the door frame 2 even at very high and changing thermal loads

borrowed low, so that the stroke of the sealing strips 5 and the spring elements 6 is sufficient to always have one to ensure perfect sealing contact.

... Fig. 2 shows another variant of a coke oven door using the cast iron according to the invention for the door body 1 and the door frame 2. Here, too, the heat-shielding component is attached directly to the door body 1 (without an air gap).

Sealing takes place by means of hammer-blow sealing strips 8, which are attached to the door body by means of hook screws 9 1 are attached. The low temperature deformation of door body 1 and door frame 2 is guaranteed a consistently good sealing con-. clock of the sealing strips 8 without a complex Readjustment is required.

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Claims (2)

Diving. Dr. jur. VOLKMAR TETZNER lawyer and patent attorney Van-Gogh-Straße 3 8000 MUNICH Telephone: (089) 79 88 03 Telegrams: "Tetzner patent Munich" Telex: 5 212 282 pate d P 5368 Patent claims: Cast iron component for coke ovens, in particular
Oven door, oven frame, flare tube lock or filling hole cover, characterized by a purely pearlitic structure, finest graphite distribution and the following
i. «» - »Mchtanalysis: carbon silicon manganese phosphorus sulfur 2.7 - 2.9% 1.6 - 1.8% 0.8 - 0.9% max. 0.1% max. 0.1% 2. Cast iron component according to claim 1, characterized by nickel, copper, chromium and / or molybdenum as a further alloy component. COPY]