RADIOISOTOPE SYSTEM TO MONITOR DUST LEVEL IN DUST CATCHERS V. N. Uzlyuk, E. M. Potapenko, V. M. Zelenin, A. K. Gashinov, and Yu. P. Bobrov

UDC 669.162.263/266:539.163

Blast-furnace top dust is collected in dust catchers and removed according to a speciall~ developed schedule organized with allowance for other elements of the blast-furnace shop production cycle. The worker responsible for removal of the dust manually connects an actuating mechanism joined directly to a disk valve. A signal to open or close the valve is transmitted as the dust catcher is filled or emptied. After the valve is opened, the dust pours out of the catcher under its own weight and the pressure exerted by the flue gases, dropping into waiting railroad cars. Dust remaining in the catcher after gravity removal is blown out under pressure by a stream of gas at 1.21.3 psig. This results in rapid wear of the disk valve and a concomitant need for its frequel replacement. Wear of the valve also increases the dust content of the operator's area and the surrounding air. Also, the operator does not always succeed in sending the valve closure signal at exactly the right time. The Dneprodzerzhinsk plant has developed and is successfully using a radioisotope system to monitor the lower level of the dust in blast-furnace dust catchers (Fig. i). The system permits the operator to automatically control emptying of the catcher while avoiding significant wear of the disk valves and contamination of the work area. A collimator 2 with a source of radioactive 137Cs is located on one side of the dust catcher i, while a r a d i a t i o n d e t e c t o r 3 is placed on the other side. The error in measuring the dust level has been reduced by designing the collimator in such a way that the beam (source) and detector are in precise focus with respect to each other. The shell of blast-furnace dust catchers is made of welded 12-mm steel plate and lined with 120 mm (thickness) of refractory brick. Thus, the total thickness of the materials through which the beam from the source must pass to reach the detector is (12.2) + (120"2) = 264 mm. This requires the use of sources of high activity and improved shielding of the device, the latter having been achieved in this case by increasing the thickness of the collimator wall. The high activity of the specimen also requires special protection for the area of the detector. To reduce the activity of the specimen a t t h e detector and collimator, the refractory brick was brought out further from the shell and recesses were built using steel plate.

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Fig. i. Diagram of dust level control furnace dust catcher.i Dneprodzerzhinsk Industrial Institute. Dneprodzerzhinsk Metallurgical Plant. from Metallurg, No. 6, pp. 16-17, June, 1979.

0026-0894/79/0506-0385507.50

9 1980 Plenum Publishing Corporation

Translated

385

The detector and collimator with source were positioned at a level such that the disk valve would close before the catcher was completely emptied, i.e., the transport lag was taken into account. Thus, to prevent the dust in the lower part of the catcher from being removed, a certain amount of dust (a dust plug) was left in the catcher. This quantity of dust, forming a layer 1400 mm high measured from the hoppe r mouth, blocked the passage of the pressurized gas. When the dust plug goes below a certain level, the detector is irradiated by the source. The resulting signal proceeds from the detector to relay block 4 (a standard GR-6 y-relay block). The contacts of the relay turn on magnetic starter 5, which controls actuator 7. The actuator closes disk valve 8 with counterweight 9, Thus preventing damage to the valve by dust being blown about by the pressurized gas. A manual control knob 6 can be used if necessary. Use of the above system has made it possible tooperationally control emptying of the dust catcher, reduce expenditures on repairing, making and replacing disk valves, and partly reduce dust contamination of the surrounding area.

SINTERER ALEKSANDR NAVRAZHIN

Ya. Tikhonov

Aleksandr Navrazhin has had luck with his mentors...more than 15 y e a r s a g o Viktor Vladimirovich Nozdrachev came to work at the sinter plant. He had a wealth of experience, having worked at the Novolipetsk Metallurgical Plant and Zaporozhstal'. He gave many useful lessons and much good advice to the young technician who came to work in crew No. 4 6 years ago. Aleksandr began as a helper. There is no time to yawn on this job: only time to remove the spilled materials from under the conveyor. After lifting the shovel for several hours, it seems that one can't go on...but it was at these difficult moments that Navrazhin remembered "I am a Komsomol member and I can work like one." With these thoughts, he caught a second wind. His colleagues at work were impressed by Navrazhin's persistence and thoroughness. He had a conversation with shift chief Viktor Ivanovich Materienko. "You have to work more quickly Sasha and remember that time does not wait. The faster you learn, the better things will go in the crew. We can't be Wasting the time of a college graduate." The young specialist was encouraged by the trust and compliments that later came his way. It turned out that several minutes could be spared from the tight schedule of the shift to see how the older comrades did their work. The sintering carts moved smoothly through the wind boxes, but Aleksandr noted that the sinterers held them up around the 6th wind box.

ll'ich Zhdanov Metallurgical Plant.

386

0026-0894/79/0506-0386507.50

Translated from Metallurg, No. 6, p. 17, June, 1979.

9 1980 Plenum Publishing Corporation