COMPOSITION INNER

SURFACE

OF

MEDIUM OF

CONDENSATE

HOT-BLAST

STOVE

ON T H E JACKETS UDC 669.162.23

A. T. Yakovenko, V. V. Zinchenko, N. V. Suntsov, I. I. Somova, and M. P. Kushnir

An a n a l y s i s of s a m p l e s of the g a s m i x t u r e u n d e r the crown jacket of a h o t - b l a s t stove shows that it cons i s t s p r i m a r i l y of O 2 and CO2, which c o n t r i b u t e s to the g a s e o u s c o r r o s i o n of the jacket. P r o c e s s e s of i n t e r c r y s t a U i t e c o r r o s i o n m a y begin in the j a c k e t when the t e m p e r a t u r e is r a i s e d . At the Donets M e t a l l u r g i c a l plant, w h e r e the h o t - b l a s t stove is heated with a m i x t u r e of furnace and natu r a l (3% by volume) g a s e s and the crown i s heated to 1300~ s a m p l e s of the condensate a r e taken f r o m under the jacket of the crown and its qualitative c o m p o s i t i o n is d e t e r m i n e d in o r d e r to elucidate the m e c h a n i s m of jacket corrosion. A connecting pipe is welded onto the crown jacket in o r d e r to take the gas s a m p l e . The heated m i x t u r e of g a s e s (with w a t e r vapor) p e n e t r a t e s to the jacket through c r a c k s and p o r e s in the lining of the crown and the insulation is fed t h r o u g h the connecting pipe to a cooled coil, condensed, and run into a r e c e i v i n g v e s s e l (see Fig. 1). The condensate a p p e a r s as a p a l e - y e l l o w fluid. A r e a c t i o n c a r r i e d out with b a r i u m c a r b o n a t e r e v e a l s the p r e s e n c e of SO42 ions in the condensate. SO~-2 ions a r e r e v e a l e d by a r e a c t i o n of the condensate with an aqueous solution of f r e e iodine:

The

8 7

i

Fig. 1. D i a g r a m of s a m p l i n g condensate f r o m under the crown j a c k e t of a h o t - b l a s t stove: 1) crown jacket; 2, 5, and 6) ShLB-1 lightweight fireclay; 3) DL-1, 2 lightweight Dinas b r i c k ; 4) l o w - d i s i n t e g r a t i o n h i g h - d e n s i t y Dinas b r i c k ; 7) connecting pipe; 8) r u b b e r hosing; 9) coil; 10) w a t e r ; 11) g l a s s ; 12) condensate.

Donets M e t a l l u r g i c a l Plant. Donets State U n i v e r s i t y . T r a n s l a t e d f r o m Metallurg, No. 3, pp. 12-13, M a r c h 1977.

This material is protected by copyright registered in the name o f Plenum Publishing Corporation, 227 West 17th Street, New York, N.Y. 10011. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher for $Z50.

160

SO U - + I2 + H~.0~SO 4 - + 2 H + + 2 I - . The NO 2- ions a r e r e v e a l e d in the condensate by a r e a c t i o n with p o t a s s i u m iodide in an acetic e n v i r o n m e n t . Before c a r r y i n g out a r e a c t i o n to r e v e a l NO 3- ions, the NO 2- ions m u s t be d i s s o c i a t e d by heating the m i x t u r e being analyzed with a m m o n i u m s a l t s . A f t e r s e p a r a t i n g the NO2-, the N Q - ions a r e r e v e a l e d by a r e a c t i o n with f e r r o u s oxide sulfide. The r e s u l t s of the quantitative c h e m i c a l a n a l y s i s of the condensate r e m o v e d in the gas c y c l e show that it contains, g / l i t e r : SO4-2 0.86; SO3 -2 0.18; N 2 (common nitrogen) 2.9. The acidity is pH= 8.57. Thus, the condensate c o n s i s t s of SO3 -2, NO2-, and NO 3- ions and when the heated gas m i x t u r e r e a c h e s the cold jacket a solution of nitric and sulfurous acids m a y f o r m on the s u r f a c e of the jacket, contributing to the jacket failure. The c o r r o s i o n s t r e n g t h of 09G2S s t e e l is g r e a t e r than that of St3, both in r e s i s t a n c e to g a s e o u s c o r r o s i o n and to c o r r o s i o n in sulfurous and nitric acids.

ADVANCED REPAIR

OF

METHODS

OF

A

FURNACE

BLAST

A. P. Burdin, and E. ]~. Vibe

V.

G.

LABOR

IN

~HE

CAPITAL

Senin,

UDC 669.162.2 : 66.044.2

During March and April of 1975 at the Chelyabinsk Metallurgical Plant, the Chelyabinsk SSMU of the Ural Blast-Furnace Repair Trust and the plant conducted Class I capital repairs of the 1386-m 3 No. 4 blast furnace. The amount of work, which determined the time for repairs, included complete replacement of the refractory lining of the stack, hearth, and hearth bottom, replacement of the stack shell, the mantle ring, and the bosh, and replacement of the cooling plates of the stack, the mantle ring, the hearth, and the hearth bottom. A chart for the basic flow of the work was set up (Fig. i). During the preparationperiod for repair of the metal structure of the shaft shell, which was delivered from the producing plant in the form of 12 individual plates, the plates were assembled in six pieces on a specially prepared stand. The 28-turn-thick plates of the shell were electroslag welded with A-820M automatic welders. Then after inspeetion-assemblyof the stack into larger pieces, the inserted and plate coolers were installed. The weight of each piece was 25 tons. The metal structure of the bosh shell was assembled in four pieces and after inspection, assembly holes were cut in it for the bolts and cooler pipes. At the moment of shutting down the blast furnace the personnel of the Central Plant Laboratory determined the height of the hearth bottom. As a result of accurately determining the condition of the hearth bottom, the iron was completely removed from the furnace. After tapping, the salamander froln the furnace water (~ 250 In 3) was fed into the stack and also into the gap between the lining and the shell for 12 h. Whenthe level of water in the furnace had reached the fourth row of coolers in the stack, it was shut off arld the furnace was held in this condition for i0 h. This aided in rapid cooling of the furnace and in good steam impregnation of the stack lining, which accelerated its removal. After draining the water froln the furnace, the repair workers furnace shell (Fig. 2).

started cutting production openings in the

The top protection was removed from the outside of the furnace from the circular platform through the six openings in the shell by flux-oxygen cutting. Later they were sealed by stationary hatches. ~[he band of Chelyabinsk SSMU of the U r a l B l a s t - F u r n a c e R e p a i r T r u s t . T r a n s l a t e d f r o m Metallurg, No. 3, pp. 1316, March, 1977.

This material is protected by copyright registered in the name o f Plenum Publishing Corporation, 22 7 West 17th Street, New York, N.Y. 10011. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise without written permission o f the publisher. A copy o f this article is available from the publisher for $7.50.

I

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