PROTECTION OF LABOR
INTRODUCTION OF EXPERIMENTAL GAS-CLEANING SYSTEM AT THE MMK G. M. Kanenko, Yu. L. Kovalenko, M. M. Cherepinskii, N. Kh. Sadykov, V. G. Petrushkov, V. N. Ermolaev, V. P. Pastushenko, and A. A. Tverskoi
UDC 669.162o252
The "VNIPIchermet6nergoochistka" Institute has developed a gas-cleaning system with an ejection-type Venturi washer which operates without a high-pressure blower and a unit which heats the gases before the blower~ This feature lowers the metal content of the gases, simplifies the gas-cleaning scheme, and allows the system to fit into open-hearth shop No~ 3 at the MMK (Magnitogorsk Metallurgical Combine). Open-hearth furnace No. 17, with a capacity of 400 tons, is operated with intensification of the steelmaking process by the delivery of 3000 m3/h oxygen to the furnace bath. The fuel used is natural gas, carburetted with low-sulfur fuel oil. Table 1 presents operating data on furnace No. 17. The gases are directed from the furnace to a KU-80 waste-heat boiler. When the gascleaning equipment and boiler are turned off, the gases are directed along a standby channel into the smokestack~ The productivity of the boiler was increased from 9 to 12-15 tons of steam per h by the inclusion of the gas-cleaning system and an increase in the amount of gas withdrawn from the furnace. Thirty to forty percent air is sucked into the boiler. The heating surface of the boiler is cleaned with a pulse-type chamber-cleaning apparatus. The gases are directed from the boiler into the Venturi washer and thence into a stationary spray tower and a separator with regulable swirler vanes. The gases then leave through the stack. Superheated water is obtained by mixing steam and water in a preheater and is delivered to the Venturi washer. The fluid flow from the Laval nozzles, travelling at about 150 m/sec, is intensively mixed in the mixing chamber (throat) of the washer and serves to remove, clean, and cool the gases. The low metal content made it possible to make the gas-cleaning equipment and stack out of stainless steel KhI8NIOT, which increases the service life of the equipment by a factor of three to four and makes it unnecessary to heat the gas. In studying the efficiency of the gas-cleaning equipment, we altered the operating conditions of the Venturi washer. These conditions depended on the temperature and rate of flow of the superheated water and the design of the Laval nozzles. It was found that stable operation of the preheater is assured and the highest gas-ejecting parameters are obtained in the washer when the pressure difference between the cold water and steam is 3-5 psig. The pressures of the resulting superheated water and steam differ negligibly, so the temperature of the water is determined mainly by the steam pressure. Water temperature is 150-195~ with a change in steam pressure from 7 to 15 psig. The productivity of the gas-cleaning equipment and the head developed by the Venturi washer increase with the temperature and rate of flow of the superheated water. With a steam pressure of 12.5 psig and superheated water with a temperature of 183~ and flow rate of 98.7 m3/h, gas flow rate before the gas-cleaning system was 290,000 m3/h (temperature 250~ and the head was 1550 Pa. The efficiency of the system in removing dust was studied during the melting period. The initial dust content was determined by the method of internal filtration, using an extractor filled with fiberglass. Final dust content was determined immediately after the separator by the method of external filtration. Dust-removal efficiency was determined at steam pressures from 11.8 psig to 15 psig (Table 2). Performance tests of the gas-cleaning system were conducted in two stages. In the first stage (regime i), the exhaust fan did not perform well and deviated from its design operating
V N I P I c h e r m e t e n e r g o o c h l s t k a I n s t i t u t e and the M a g n i t o g o r s k M e t a l l u r g i c a l T r a n s l a t e d from M e t a l l u r g , No. 8, pp. 43-44, August, 1982.
308
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Combine.
9 1983 Plenum Publishing Corporation
TABLE i. Operating Conditions of OpenHearth Furnace ,~ O
!
[o
...] m
I 4.a,--~e~
[Oxwen consumotmn,
O
S
"
3
Steelmaking periods "~ I~o ~ ~ ~ a - ~ / i n f l a m e ~in bath Fettling Cold charging Heating Hot m e t a l addition Melting Refining
0--30 0--45 0--30 0--30 1--30 0--45
2,5 3,8 3,8 1,5 1,2 I, 2
500 I000 1000 500 500 500
-1,0 i ,0 ----
---3,0 3,0 3,0
TABLE 2. Results of Performance Tests of GasCleaning System Operating r e g i m e Parameters Consumption in O H furnace oxygen, m a / h natural gas, m S / h f~el oil, k g / h Head developed by Venturi washer, Pa Gas flow rate, thousands ofm~/h before g a s - c l e a n i n g system after g as-cleaning sysiem Gas temperature, ~ before g a s - c l e a n i n g system after gas-cleaning system Dust content of gas 9 1 oefore g a s - c l e a n i n g system, g / n m after gas-cIeaning s y s t e m , g / m S Steam pressure, ps~g T e m p e r a t u r e of superheated water, "C Flow rate of superheated water, ma/h Unit flow rate of suRerheated Kater, l i t e r s / ~ l < (u~derthe discharge conmtmnsr
TABLE 3. Performance with Swirler
S
3000 1200 550
3000 1200 450
3000 t200 500
1100
1400
I650
230 190
282 242
257 214
300 70,5
290 71
275
4,0 0,067 i~ ,8
3,84 0,060 13,0
183 68,8 0,36
70 3,9 0,042 15,0
186 94
192 89
0,39
0,42
Tests of Separator
o
30 45 55
236 210,5 189
900 1700 2200
12, ~ 11,0 9,9
184 185 185
g7,5 96,5 96.3
parameters. Gas flow rate through the gas-cleaning system was increased after the fan was reconstructed (regimes 2 and 3). We tested several designs of Laval nozzle. The diameter of the nozzle throat was 12 ram for all of the regimes (design diameter), while the divergence angle of the diffuser was 6 ~ for regimes 1 and 3 and i0 ~ for regime 2. It can be concluded from an analysis of the data in Table 2 that efficient gas cleaning -achieving a final dust content below I00 mg/m 3 -- requires that steam pressure be at least 12 psig, the unit flow rate of the superheated water be at least 0.42 liters/m a (under the discharge conditions), and the temperature of the water be at least 180~ When the temperature of the superheated water drops below 175~ gas-cleaning efficiency suffers and the final dust content exceeds i00 mg/m 3. An increase in the diffuser divergence angle from 6 to !0 ~ and, accordingly, an increase in the expansion angle of the jet from
309
i0 to 16 ~ fail
to improve dust-cleaning efficency.
The performance of the separator depends on the inclination of the swirlervanes ab (Table 3). When ab, reckoned from the vertical, is less than 30 ~ , drops are seen being carried away from the stack. When ~b > 30~ the fluid resistance of the separator is increased sharply. Thus, the optimum inclination for the swirler vanes is 30 ~ . The gases are cooled from 250-300 to 65-71~ in the Venturi washer. of the dirty water in the seal is I-3~ lower than that of the gas.
The temperature
Considering the moderate capital expenditures and low metal content, the gas-cleaning system with ejection-type Venturi washers can be used to clean OH furnace gases during the reconstruction of existing shops and to intensify oxygen-blowing of the bath.
ALLEVIATING HAZARDS AND IMPROVING WORKING CONDITIONS ON THE 140 TUBE-PRODUCTION UNIT E. A. Dervoed, I. G. Getiya, V. K. Shumilin, V. P. Makarov, and A. I. Zhukov
In 1976 the tube-rolling shop at the Sinarskii Pipe Plant implemented a series of measures which eliminated a number of work hazards and improved working conditions. Under the original design, rods were tilted manually when loaded onto an inclined table prior to charging onto the breaking press. However, when a curved rod was tilted, the next, straight rod would begin to roll -- endangering the worker. To prevent jamming of curved rods while avoiding the above situation, a rod manipulator (Fig. i) was installed. Under the original design, the electropneumatic relays (EPR's) installed in the shop to improve the response of the system and shorten auxiliary operations in rolling were placed near the auxiliary mechanisms. It was determined during run-in of the equipment that this was an unfortunate choice of location, since the constant action of water, scale, and vibrations from the mechanisms quickly caused the relays to malfunction and reduced the reliability of the equipment as a whole. Also, the relays were hard to reach for servicing and replacement. The relays were therefore moved to an easily reached area to make the system more reliable and improve working conditions. Given the large number of relays in the shop (280 relays were installed in the hot conversion section), the release of compressed air into the atmosphere led to a high noise level in the shop. To reduce the noise, ten to twenty EPR's were placed in large-diameter pipes (Fig. 2). This reduced the pressure and velocity of the compressed air as it was released from the relays, directed the air through the pipes into a water drain, and reduced the noise level at work stations by a factor of 2.7. As a result, the noise level now does not exceed 85 dB, in accordance with GOST 12.1.003--76.
,On rollert a b l e ~
/.'/////f777
~, ~
~ ~-
.
.
.
.
/7/2
~/,
Fig. i. Improved scheme for tilting rods with a manipulator: i) rods; 2) manipulator; 3) air cylinders.
ing.
310
Sinarskii Pipe Plant and the All-Union Correspondence Institute of Mechanical EngineerTranslated from Metallurg, No. 8, p. 44, August, 1982.
0026-0894/82/0708-0310507.50
9 1983 Plenum Publishing Corporation
