SU1492204A1 - Method of regenerating shielding gas while heat treating metal in bell-type furnace compartment - Google Patents

Abstract

The method relates to the utilization of protective gas, in particular, to the use of furnace hydrogen, which is separated from bell-type furnaces during high-temperature annealing of electrical steels. The purpose of the invention is to save energy. The heating of the subsequent bell furnace begins when the previous furnace, from which the spent hydrogen is taken, reaches a temperature of 1050 ° C, which allows you to select hydrogen that does not have harmful impurities, and to ensure the reuse of the maximum amount of hydrogen (the hydrogen consumption during heating and soaking up) the whole period of heating the subsequent furnace. Oven hydrogen is used when the subsequent furnace is heated above 1050 ° C and up to 1200 ° C with a holding of 1200 ° C, as well as during cooling down to 250-150 ° C. When the heating temperature of the subsequent furnace reaches 850 ° C, fresh hydrogen is added to it, as the previous furnace goes to the stage of cooling and reducing the consumption of fresh hydrogen. Compressing spent hydrogen before being fed into a subsequent furnace up to 60-150 kgf / m ² provides intensive mixing and shortening the processing cycle time and improving its quality. 1 hp ff, 1 ill.

Description

The invention relates to methods for utilization of protective gas, in particular, to the use of furnace hydrogen, which is separated from bell-type furnaces during high-temperature annealing of electrical steels, and can be applied in the metallurgical and machine-building industry.

The purpose of the invention is to save energy.

The heating of the furnace after the furnace begins when the furnace reaches the temperature from which the spent hydrogen is taken. This combination ensures the selection of furnace hydrogen, which has no harmful impurities; use of the maximum amount (m / h) of furnace hydrogen taken from the furnace during the whole period of heating the subsequent

, g, t; li goch-; 11the maximum possible / nremet1n (h) and, therefore, maximum energy savings during one heat treatment cycle,

When the furnace is heated below 1050 C, hydrogen extracted from the neqFioH contains harmful impurities (CO. CO, CH), which is formed during the decomposition of magnesium oxide hydrate and sublimation of hydrocarbon-containing components that are not removed from the surface of the metal (strip) during degreasing.

When the furnace is heated up to 1050 ° C (up to 1200 ° C) and when cooled from up to 150 ° C, the extracted hydrogen from the furnace does not contain harmful impurities and, therefore, it must be reused when heating the steel in the subsequent bell furnace.

The absence of harmful impurities in the indicated temperature range is explained by the complete removal from the furnace volume of the products of decomposition of magnesium oxide hydrate and the sublimation of hydrocarbon lubricants,

At temperatures below 150 ° C, the metal is not oxidized after the furnace is unpacked and, therefore, there is no need

the use of hydrogen in the furnace,

This temperature is optimal for stopping the selection and supply of hydrogen and provides a reduction in the blaring cycle and the absence of metal oxidation.

The protective gas in the bell furnace, starting from and for the period of holding and cooling to 150 ° C, contains 100% by volume H at humidity, corresponding to its dew point (-20) - (-40) C. Kiln gas at, leaving the same furnace when heated to 1050 ° C contains,%: CO 0.04 - 0.085; CO 0.05-0.65; -CH4. 0.01 - 0.095; % 0.1 - 1.0 humidity corresponds to the dew point (+40) - (-20) ° C; H - the rest is up to 100, Therefore, the use of protective gas (furnace hydrogen) discharged from the furnace in the temperature range of 1050-1200-150 ° C to heat the metal in the post-stage (up to 200 ° C furnace furnace ensures protection of the metal surface from oxidation ,

Ko f furnace hydrogen conversion before; 1 hour (. I in the next furnace in the pressure range of 60-150 kg / m provides directional movement

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gases in the bell furnace, reliable contacting of hydrogen with the heat-treated metal and, thereby, improves the quality of the heat-treated metal.

When hydrogen pressure is supplied-. Going to the furnace, below 60 kgf / m, the gas movement in the furnace slows down, which increases the flow of protective gas to the furnace and reduces the capacity of the furnace. When the pressure of hydrogen supplied to the furnace exceeds 150 kgf / m, the tightness of the seals around the perimeter 5 of the cap support part is broken, which leads to the leakage of hydrogen from the furnace and the need to increase its flow to the furnace, to leak and oxygen to the inside of the furnace, which causes

0 oxidation of heat treatable metal and the formation of an explosive mixture inside the furnace.

The addition of fresh hydrogen to the hydrogen furnace supplied to the next 5 conch furnace is produced during heating of the furnace, starting at 850 ° C, since the heating time of the subsequent furnace to 850 ° C is almost equal to the heating time of the furnace,

The amount of furnace hydrogen is taken from 1050 up to and at a temperature of 1200 ° C. The amount of hydrogen taken off the furnace fed to the subsequent furnace is 60 m / h for this type of bell furnaces.

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In the period when in the oven from which -. the swarm takes away the hydrogen from the furnace, starts cooling, the amount of the hydrogen taken off is sharply reduced, t, e. when cooled, 10-15 m / h of hydrogen are fed to the furnace. Therefore, starting with, a gas mixture consisting of 10–15 m / h of furnace hydrogen and 50–45 m / h of fresh hydrogen is fed to the subsequent bell furnace.

Utilization of furnace hydrogen will provide energy savings (electricity, steam), materials (catalyst, adsorbent, absorbent, alkali) and water needed to produce fresh gas.

The drawing shows a circuit for carrying out a method for utilizing a protective gas.

The diagram shows two ovens - oven 1 (previous) and oven 2 (after

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blowing), which are equipped with a common collector 3 for supplying fresh vpodoroda The latter is connected to the furnace 1 with a pipe 4, equipped with a valve 5, and with a furnace 2 - with a pipe 6, equipped with a valve 7.

The furnace 1 is equipped with a pipeline 8 for removing hydrogen from the furnace volume - a regulating valve 9 installed on it and a valve 10, and a furnace 2 | with a pipeline 11 for removing hydrogen from the furnace volume with a regulating valve 12 installed on it and a valve 13.

The furnace 1 is connected to the furnace 2 by a line that includes the suction pipe 14 (which is connected to the pipework 8 between the regulating valve 9 and the valve 10) with the valves 15 and 16 installed on it in series, the refrigerator 17, and the output device 18 and the discharge pipe 19 which is connected to the furnace 2 by two discharge pipelines, pipeline 20 with a valve 21 installed on it and pipeline 22, with a valve 23 installed on it successively, an ejector 24, a valve 25.

The discharge pipe 19 is connected to the discharge plug pipe 26 and is equipped with an adjusting valve 27. The ejector 24 is connected to the suction pipe 14 between the valves 15 and 16 by the pipe 28 with the valve 29 installed on it.

The fresh water inlet manifold 3 is connected to the suction pipe 14 between the valve 16 and the refrigerator 17 by the pipe 30 with the valve 31 installed on it.

T the intake device 18 has a bypass pipe 32 with a valve 33, which connects the injection pipe 19 to the suction pipe 14 between the valve 16 and the refrigerator 17.

Sequential use of a fuel-injecting device and an ejector in the stage of supplying additional fresh hydrogen allows the use of furnace hydrogen, and thus allows the gas mixture consisting of furnace and fresh hydrogen heated to 150-200 ° C to be supplied to the bell-type furnace.

The temperature of the gas mixture is determined by the formula

 ic.

Vn

t, 4

V. V -c "

respectively, the volumes of fresh and furnace hydrogen, m / h; t - according to tempera5

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tours of fresh and furnace hydrogen, C.

For example, for V 50 m / h, V

 10 m / h, t,

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25 ° C. . „We have tff 166 S.

The proposed method was implemented on two bell-type furnaces for high-temperature annealing of electrical steel coils in the atmosphere of hydrogen installed in a sheet-rolling shop.

Before conducting experimental studies, the beginning of the heating stage of the subsequent bell-type furnace 2 was combined with the temperature of 1050 C of the bell-type furnace 1, from which the furnace hydrogen was taken.

In the initial period, furnaces 1 and 2, previously purged with nitrogen, have shut-off devices and valves closed, the gas blower does not work.

After being purged with nitrogen and switching on electric heaters (not shown) from collector 3, furnace 1 was fed 60 m / h of fresh hydrogen through manifold 3 and valve 5.

As the furnace was filled with fresh hydrogen, the pressure in the furnace increased and, after reaching 40 kgf / m, the control valve 9 was put into operation, which released hydrogen from the furnace through pipeline 8 and valve 10 to the afterburning.

Before reaching 1050 ° C, the electric heaters of the furnace 2, which was pre-filled with nitrogen, were turned on, the operating apparatus 18 was switched on in T, which worked on itself through the bypass pipeline 32, valve 33 and refrigerator 17. Then valve 10 was closed, valve 15 and 16 were opened, the gate valve 33 was smoothly covered and the furnace hydrogen from furnace 1 through pipeline 14 was taken with a liquid-filling device 18 and supplied with a pressure of 100 kgf / m through pipeline 19 to the discharge plug via the regulating valve 27 for reburning.

After reaching 1050 ° C in the furnace 1, the valve 21 was opened, and the furnace hydrogen from furnace 1 through the pipeline 20 s

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iipn: .h from: 6 () g-. / hr -vcdgo In ldorola 1: Koshg kpV 1 allotted p pech1 - p. cpl / lO h (starting with L i 03 (P;: P i and; 11 m et1e of the furnace 1 and.-hichiva with (4: (i; 4-iiiMit; g; 1 dig, B1.1ierzh1 and in the furnace I 71 And t () p; zl.T1, m1 chodpm into the furnace;,:; o -i :: m-; L.-1,

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   . .. ,,; I l - .., - (, 1 ichet., See chh ga ichz, CMJCTOH- I.. I Ii) P vf / h, ninaBjj; it f th fresh € gn nn / v la and il: i / 4 of hydrogen, hsgg ira1.) l) | h kochpakono; Ketchi 1, ia; 1ДЯ1Ц (-м) г: {VFO time in the stage of cooling At 1ПЫ;

. i, 4H iroi ii iior chedo) atelg, but orKpi-i- i. L And on ti ch1chro1 11de iO and chach iiiLtv-ai i,: 9 and 2, (.1nali щиi chi Zl i: 111. With great water | 1D g.) Lu rb- BhiM vcTpoHiyruori 18 otskkchll- 1 :, 1u from i-- ii, L: io K.). 1De1-.,; ora) 4t, pt 3); hr-h i;, - advi -zhu jl, I iiyOo-iipoMi. ji i -,: o4; vu 4 v4ni-c 1 / and no rpy () O iiV 11 chodch 2 ichprand and hh v; the tector 2, i) fresh hydrogen sgleshia-chs. Kiln 1 kiln 1 kiln 1, iacacbi-: atema ej {T via a pipeline through 8 aich: -: at i9. After the ejector, the gauge temperature is 1 iO-200 С (50 m / h C1 1: the temperature of the gas is 2; r s. 10 m / h of the furnace room; o,; (ip (X4 .a those -1per) uy 1200 - 700 g) and 1 gm ch l in iii 4 2.

In vrnT cherioch .m1 h, it is 2 kpdder + ivadosch, h o vrci A, and the stove a.tm myfeg a g boagyad.adast, 1.:chapach (12), 1 d 111g; ni

  ; Bepiiit Hiin stage of heating. Oi 2 to T () (U (i.e., its translation into cuddles: PLC of the Rzhki. O oven 2 of the ji 1 1 I -, tochto 60 sveto-: 1H) iyr1) yes , for which the sequence hh nd; h-: and. 1 chadvizhku 7 pa t ruiopro-: -1 × 1 6 supply fresh hydrogen to ne i- f.;) I - 1-1 h |: h. - to waste i. B iaiipoita,) bTK4M4ajTn t year - ii.i all. r; ifu icTBo 1М, closed off chad

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 t1cho of furnace hydrogen in;: Toi t CTajuin And Iyuchi 2 throat; most of the pipe;: p1: 1 ode 1 1 through the adjustable regulating valve 12 and the valve 13 for afterburning.

11 June 11 hydrogen taken from the furnace located at the same time. steel and cooling, during the experiment for 50 h (to the Bepiueiiim stage of cooling; 1eni) was discharged through pipeline 8 through the regulation and dialing of 1saplan 9 and valve 10 to afterburning (this furnace hydrogen can be used on the bell furnaces;; this is the time in the va grena stage).

1Tspol1, the proposed method is free from e; to get the given i 4ioiu; TB of the heat-treating metal, h, the reduction of the consumption of fresh hydrogen by 2780 m per kiln and a 1 dig. O h).

 About Pm Uda Invention

Claims (1)

one . ioso uti iza; p1I shielding gas at terry processing of the metal in the furnaces of bell-type furnaces, including g: | boron shielding gas from the bell-type ng 11 processing, feed of the h; icite gas to the village of publish the stove., psgsgstno with Jto6anKoii fresh zaschtnoprrr-ia, (I tl and h ay y and s, THAT, With a helix higher1 economical, GOSTG1, the selection of the spent protective gas begins with the tag-sherature heating I. -i 105 ((, and continue to produce ngo It chr - 7 cent of exposure and cooling of the dg-, 250– 150 ° C temperature, then the sampled crystalline gas is compressed and fed with a pressure of 60–150 kgf / m during the period of its heating up to 1200 C, the subsequent bell furnace, and the fresh gas of this gas, this is started when the furnace temperature is reached, and as a fresh gas itnogo hydrogen gas is used, 2, the method according to claim 1, characterized by III, IT, so that in the stage of supplying additional fresh hydrogen to the subsequent furnace, the hydrogen taken out of the furnace and the added fresh hydrogen are combusted by means of the device and the ejector and fed the mixture, heated to 150-200 C, Fresh Hydrogen Supply