Stahl-Zentrum. Influence of coke quality on BF hearth lifetime and operation results. Walter Hartig, Rongshan Lin * ) AG der Dillinger Huettenwerke

Transcription

1 Influence of coke quality on BF hearth lifetime and operation results Walter Hartig, Rongshan Lin * ) AG der Dillinger Huettenwerke 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 1

2 Introduction Content Blast furnace campaign results Comparison of No. 5 blast furnace before and after its enlargement Influence of the coke quality on BF operation and wear Investigation of hearth refractory wearing Main consequence of the BF performance Modification of the BF hearth profile and lining concept Revamping of coke batteries to secure coke production Improvement of the coke quality Conclusion 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 2

3 Introduction ROGESA (Roheisengesellschaft Saar) - a joint venture of AG der Dillinger Hüttenwerke (a heavy plate producer) and Saarstahl AG (a long products manufacturer) in Saarland, Germany Founded in April 1981 to concentrate the hot metal production only at the Dillinger site since 1985 with the new construction No. 5 BF HM production facilities: ore beddings, 2 sinter strands; No. 4 and No. 5 blast furnaces in operation and No. 3 blast furnace in stand-by Enlargement of both operating blast furnaces at their last relining Actual production capacity of 4.6 Mio thm/a to supply both steel shops with the hot metal Discussions of the 2 nd campaign results of No. 5 blast furnace after its enlargement 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 3

4 Comparison of No. 5 BF before and after its Enlargement BF 5 old BF 5 enlarged changes Start of campaign Dez. 85 Aug. 97 Hearth diameter m % Hearth area m ,1 +19% Working height m 24,7 Working Volume m % Inner Volume m % Number of tuyeres Daily production (average) t/24h % Productivity t/m² 24h 54,9 58,8 +7% Productivity (w. v.) t/m³ 24h 2,35 2,57 +9% Campaign life years 11,4 8.3 *) Total HM production Mt 20, *) Production t/m³ w.v *) *) just until the interim repair 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 4

5 Hearth lining concept before and after BF enlargement No. 5 BF, 11 m in Dec 85 standard carbon blocks low initial sump depth thick bottom layer low bottom cooling due to 2 layers of chamotte bricks No. 5 BF, 12 m in Aug 97 Built on the existing fundament large super-microporous carbon blocks Low initial sump depth a sacrifice bottom layer use of a ceramic protective wall 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 5

6 Hearth lining concept with ceramic protective wall with ceramic wall without ceramic wall (lost after 6 months operation) 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 6

7 Coke Supply and Coke Quality 100 Nut coke Coke share (%) CSR (%) ZKS coke CdC coke Coke A Coke B Coke C Coke D ZKS coke External cokes Period 1 Period 2 Period 3 Period 4 CdC coke 35 Jan.98 Jan.99 Jan.00 Jan.01 Jan.02 Jan.03 Jan.04 Jan.05 Jan Vollsitzung des Hochofenausschusses/Kokereiausschuss 7

8 Operation Data of enlarged No. 5 Blast Furnace Production (thm/d) Reducing agents (kg/thm) Coke total (kg/thm) PCI (kg/thm) Period 1 Period 2 Period 3 Period 4 60 Jan.98 Jan.99 Jan.00 Jan.01 Jan.02 Jan.03 Jan.04 Jan.05 Jan Vollsitzung des Hochofenausschusses/Kokereiausschuss 8

9 Operation Data of enlarged No. 5 Blast Furnace O2-addition (Nm 3 /thm) Steam addition (g/nm 3 ) P total (bar) CO2/(CO+CO2) (%) Period 1 Period 2 Period 3 Period 4 42 Jan.98 Jan.99 Jan.00 Jan.01 Jan.02 Jan.03 Jan.04 Jan.05 Jan Vollsitzung des Hochofenausschusses/Kokereiausschuss 9

10 Hearth Temperature Monitoring Hearth Temperature ( C) Bola 5 hot Bola 5 cold Bola 6 hot Bola 6 cold Gela 1 hot Gela 1 cold Gela 2 hot Gela 2 cold Gela 3 hot Gela 3 cold Period 1 Period 2 Period 3 Period 4 Sep 97 Jul 98 Apr 99 Feb 00 Dez 00 Okt 01 Aug 02 Jun 03 Apr 04 Jan 05 Nov Vollsitzung des Hochofenausschusses/Kokereiausschuss 10

11 Investigation of the refractory lining wear (Formation of brittle zones) Wear profile of the side wall of No. 5 BF Carbon Block G4 (under No.1 Tuyere) 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 11

12 Investigation of the refractory lining wear (Formation of brittle zones) m Wear profile of the side wall of No. 5 BF St a hl -Z en tru Carbon Block G3 (under No 16 tuyere) 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss G3 12

13 Investigation of the refractory lining wear TH TH Wear profile of 1 st side wall layer (G1) unsymmetrical wear initial carbon block of 1,500 mm residual thickness down to 100 mm after around 8 years Formation of brittle zones is responsible for the side wall wear intial C block cold face intial C block hot face resitual thickness 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 13

14 Investigation of the refractory lining wear (Erosion wear) Wear profile of the bottom layer B5 of No. 5 BF 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 14

15 wear profiles of the refractory lining Tuyere 10 Tuyere Vollsitzung des Hochofenausschusses/Kokereiausschuss 15

16 Main consequences and measures Modification of the BF hearth profile and refractory lining concept Changes of the hearth profile and cooling system Adaptation of the refractory lining concept based on the experiences gained in the past Revamping coke batteries to ensure the own coke supply New construction of a coke battery (No. 3 coke battery) Revamping and reconstruction of the No. 1 coke battery Improvement of coke quality Selection of suitable coking coals for stamping charging Quality control of the coking coals delivery and storage 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 16

17 New lining concept of No. 5 blast furnace No. 5 BF, 12 m in Aug 97 large super-microporous carbon blocks sump depth not ideal a sacrifice bottom layer use of a ceramic protective wall No. 5 BF, 12 m in Oct. 10 Change of the hearth profile, however, limited by the existing fundament Changing cooling from staves to channel Use of large carbon blocks Enlargement of the initial sump depth Use of the ceramic protective wall built conically 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 17

18 Evolution of the hearth profile, cooling system and refractory lining concept No. 5 BF, 11 m, 1 st campaign No. 5 BF, 12 m, 2 nd campaign No. 5 BF, 12 m, 3 rd campaign 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 18

19 Evolution of the coke production 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 19

20 Selection of import coking coals 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 20

21 Evolution of the coke quality I40/I Vollsitzung des Hochofenausschusses/Kokereiausschuss 21

22 Evolution of the coke quality CSR/CRI 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 22

23 Coal injection rate vs CSR 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 23

24 Conclusion BF campaign life is mainly determined by shaft cooling and hearth refractory lining wear. Shaft cooling wear can be minimised by use of copper staves. Hearth lining wear remains serious concerns for BF operator. Key points of hearth wear control are: proper design of hearth geometry and lining, selection of the carbon block material, optimising BF operation such as stoppage, tuyere damage and water leakage The coke quality is one of the most important key parameters. 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss 24

25 Thank you for your kind attention 135 Vollsitzung des Hochofenausschusses/Kokereiausschuss