JP5978816B2 - Recovery / reuse method and recovery / reuse device for inert gas after heat treatment - Google Patents

Description

  In the present invention, when a metal product or the like is heat-treated under atmosphere control, particularly when a titanium strip coil is annealed in a batch heat treatment furnace, an inert gas typified by argon gas supplied into the furnace is heat-treated. The present invention relates to a method and apparatus for collection and reuse after completion.

  Titanium has a high corrosion resistance because its surface is covered with an oxide film at room temperature, but at high temperatures it reacts with carbon, oxygen, etc. to produce carbides, oxides, etc. on the surface, causing discoloration and poor appearance. May occur or may affect the performance of the product.

  Therefore, the heat treatment for heating titanium to a high temperature is usually performed in a vacuum or an inert gas atmosphere such as argon gas, using a sealable container. In the case of the heat treatment using argon gas as the atmospheric gas, a purity of 99% or more is required in order to prevent quality deterioration of titanium.

  For example, in Patent Document 1, when materials of titanium and a titanium alloy are charged into a batch furnace, the inside of the furnace is evacuated, and the inside of the furnace is heated so that the highest temperature part of the material reaches 380 to 480 ° C. A batch heat treatment method of titanium and a titanium alloy is described in which the furnace temperature is switched to the heat treatment temperature, and after 20 minutes or more have passed since the switching, the vacuum exhaust is stopped and the argon gas is introduced into the furnace.

  Further, in Patent Document 2, when a coil of titanium strip is charged into a bell-type batch annealing furnace and subjected to recrystallization heat treatment, the inside of the furnace is decompressed to 20 hPa or less, then argon gas is introduced, and atmospheric pressure +50 hPa or more is introduced. After returning to the positive pressure and starting heating, soaking for 4 hours or more at a material temperature in the range of 250 to 480 ° C., the inside of the furnace is again reduced to 20 hPa or less, and then argon gas is introduced to the furnace. It describes a batch annealing method for titanium strips in which the internal pressure is returned to atmospheric pressure + a positive pressure of 50 hPa or higher, soaked at a predetermined temperature, and then cooled in the gas atmosphere.

  In a vacuum annealing furnace for heat-treating a titanium strip coil, conventionally, after using argon gas as an atmospheric gas, it has been directly diffused into the atmosphere when the furnace is opened.

  In an ironworks or the like, normally, in order to supply argon gas, oxygen, or the like to a furnace in each process, a high-purity gas is collected and used using a cryogenic liquefaction separation apparatus using air as a raw material. Further, Patent Documents 3, 4, 5, and 6 disclose methods of recovering used argon gas and the like, purifying them with high purity using a cryogenic liquefaction separation apparatus, and reusing them.

Since argon gas purified by a large-scale facility is inactive, impurity components can be easily removed, and it can be purified to a high purity of the order of 99%. In addition, the argon gas after use can be refined with a recovery rate of 80% or more, and a system that can be supplied at low cost as industrial gas is prepared.
On the other hand, in a vacuum annealing furnace of a titanium strip coil, argon gas is consumed in large quantities despite being expensive, and therefore, it has been desired to reuse it.
However, neither of Patent Documents 1 and 2 mentions the reuse of Ar gas.

JP-A-62-284055 JP-A-7-90524 JP 59-39800 A JP 59-46473 A JP 59-202380 A JP 60-122709 A

  In the present invention, when a heat treatment object, in particular, a titanium strip coil is heat-treated in a batch-type heat treatment furnace, a high-purity inert gas such as argon gas introduced as an atmospheric gas into the furnace is recovered after the heat treatment is finished and purified. An object of the present invention is to reduce the production cost by using it again as the atmosphere forming gas, and to provide a method for recovering and reusing an inert gas and an apparatus therefor for solving the problem.

The gist of the present invention for solving the above problems is as described below.
(1) A plurality of batch-type heat treatment furnaces containing a heat treatment object made of titanium or a titanium alloy material are installed, and the inert gas forming an atmosphere in one furnace of the batch-type heat treatment furnace is removed after the heat treatment is completed. the heat radiation mechanism were collected in a buffer tank installed in the recovered inert gas after purification to a purity of 99% or more by using a cryogenic separation method, as the atmosphere forming gas in the furnace of the other batch heat treatment furnace A method for recovering and reusing an inert gas after heat treatment, characterized by being reused.
( 2 ) The method for recovering / reusing an inert gas after heat treatment according to (1 ), wherein the heat treatment object is a titanium strip coil.
(3) and a vacuum pump for recovering a plurality of batch type heat treatment furnace containing a heat-treated object made of titanium or a titanium alloy material, the inert gas through the connecting line from the plurality of batch-type heat treatment furnace, A dust removing device for filtering the collected inert gas, a buffer tank provided with a heat dissipation mechanism, a compressor pump, a purifying device for purifying the collected and dusted inert gas to a purity of 99% or more, and a purified inert gas And connecting the vacuum pump to the storage tank with a pipe line with valves interposed in this order to form a gas recovery line, and a plurality of batch-type heat treatment furnaces are connected to the storage tank . until each, connected by conduit interposed valves, and characterized in that connected to the gas supply line, respectively at connecting pipeline to the plurality of batch-type heat treatment furnace to the vacuum pump Recovery and reuse system of the inert gas after the heat treatment that.
(4) recovery and reuse system of the inert gas after the heat treatment according to (3), characterized in that a said gas collecting pipe with the inert gas recovery flow measurement apparatus.
(5) and the buffer tank and the gas pressure amount in the storage tank, recovery and re-inert gas after the heat treatment according to (3) or (4), characterized in that a means for measuring the purity Use device.

According to the present invention, not only the inert gas such as argon gas that forms the atmosphere of the batch heat treatment furnace can be reused many times, but also the exhaust inert gas from multiple furnaces can be efficiently recovered and reused. Reduction of heat treatment cost can be achieved.
Further, although the inert gas itself is not toxic, it is possible to eliminate the risk of oxygen deficiency caused by, for example, argon gas heavier than the average molecular weight of air staying in a pit in a factory.

It is a sketch of the inert gas collection | recovery / reuse apparatus of this invention provided with two batch type heat processing furnaces. It is a figure which shows the piping system of the collection | recovery / reuse apparatus of the inert gas of this invention provided with two batch type heat processing furnaces. It is a figure which shows the aspect which collect | recovers inert gas from a heat processing furnace. It is a figure which shows the aspect which supplies an inert gas to the heat processing furnace.

The present invention will be described below.
FIG. 1 is a sketch of an inert gas recovery / reuse apparatus of the present invention having two batch heat treatment furnaces. As shown in the drawing, two batch heat treatment furnaces 1 and 1 ′ have one unit. An inert gas recovery / reuse device 18 is also used.
Each batch heat treatment furnace is provided with vacuum pumps 21 and 21 'for exhaust.
The evacuation pumps 21 and 21 'are for exhausting the atmosphere that has entered the furnace when the material to be heat treated such as the coil 20 is taken in and out of the furnace. In order to prevent the atmosphere from entering the pipe and diluting the argon gas by the atmosphere, the atmosphere inside the furnace is discharged by a pipe provided separately from the pipe of the inert gas recovery / reuse device 18. Thus, vacuum can be drawn.

FIG. 2 shows a piping system of an inert gas recovery / reuse apparatus of the present invention having two batch heat treatment furnaces.
Connecting line 2 connected to the batch type heat treatment furnace 1 on the left side in the figure, in the middle, then branches to the gas recovery pipe 3 and the gas supply pipe 4, the gas recovery pipe 3, valves 9, the vacuum pump 5, the valve 10, the dust removing device 7 , the valve 11 , the buffer tank 12, the valve 14, the compressor pump 6, the valve 15, the purifying device 13, and the valve 16 are connected to the suction side of the storage tank 17 in this order .
The gas supply line 4 is connected to the supply side of the storage tank 17 through the valve 8 from the heat treatment furnace side.

The connecting pipe 2 'connected to the heat treatment furnace 1' on the right side in the figure branches on the way to the gas recovery pipe 3 ' and the gas supply pipe 4', and the gas recovery pipe 3 ' is connected to the valve 9'. Between the valve 9 and the vacuum pump 5, the gas recovery line 3 on the heat treatment furnace 1 side is joined and connected.
The gas supply line 4 'is joined and connected to the gas recovery line 3 on the heat treatment furnace 1 side from the heat treatment furnace 1' side through the valve 8 ' between the valve 8 and the storage tank .

  Depending on the timing of vacuuming in the batch type heat treatment furnace and the timing of supplying the inert gas, the inert gas recovered from the batch type heat treatment furnaces 1 and 1 'is heat-treated such as titanium coils by heating and vacuuming. It may contain dust due to impurity gas components generated from the object, oils and fats decomposed by heat treatment and heating.

In order to remove such impurities in the inert gas, the dust removing device 7 is installed via the gas recovery line 3 and the vacuum pump 5 from the batch heat treatment furnaces 1, 1 ′.
As the dust removing device 7 for removing impurities, general devices such as a washing tower, a venturi scrubber, an electrostatic precipitator, a filter and the like can be used alone or in combination. Although not shown, the dust removed by the dust removing device is used. Etc. are discharged out of the circuit.
The recovered gas after dust removal is primarily stored in the buffer tank 12. If the argon gas is radiated in this buffer tank 12, the burden on the purification apparatus is reduced.

For example, when argon gas is used as the atmospheric gas, a purity of 99% or more is required. Therefore, the purifier 13 for increasing the purity of the collected gas that has been removed from dust is connected to the gas recovery line 3 from the buffer tank 12 and the compressor pump 6 It is installed via.
For the concentration of a general inert gas, a means (deep-cooling separation) or the like of liquefying and rectifying a dust-removed gas and separating it into a high-purity gas using a difference in boiling point is known. The composition of the exhaust inert gas in the vacuum annealing furnace is 90% or more of argon. By using a simpler apparatus, it can be easily purified in large quantities and with high purity.

  In the case of heat treatment of the titanium strip coil, impurities are collected by vacuum heating before reaching the heat treatment temperature, the amount of impure gas generated after the heat treatment is small, and the composition of the inert gas is also compared with that before the heat treatment. It does not decrease greatly. By using the cryogenic separator, for example, when argon gas is used as an inert gas, 90% or more can be recovered with a purity of 99% or more, and the argon gas discharged together with the impurity gas is 10%. It is as follows.

FIG. 3 is a diagram showing an aspect at the time of collecting the inert gas described above.
The valve 9 is opened from the batch type heat treatment furnace 1 on the left side of the drawing, and the inert gas after the heat treatment is drawn in by the vacuum pump 5 through the connection line 2 and the gas recovery line 3, and the dust removing device 7 is Then, it is recovered in the buffer tank 12.
After the dust removal is completed, the valve 14 is opened, compressed by the compressor pump 6 via the recovery pipe 3, and the purifier 13 removes impure gases such as carbon dioxide and oxygen. The inert gas after purification is recovered in the purification tank 17 via the recovery line 3 with the valve 16 opened. The recovered inert gas has a purity of about 99% and can be sufficiently reused.
On the other hand, in the batch-type heat treatment furnace 1 after the argon gas has been collected, air is introduced into the batch-type heat treatment furnace 1 through an exhaust vacuum pump 21 or a valve (not shown). Is released.

  FIG. 4 is a view showing a mode in which the inert gas recovered in the purification tank 17 is supplied to the heat treatment furnace 1 ′ on the right side in the drawing.

  A heat treatment object such as a titanium coil is accommodated in the batch heat treatment furnace 1 ′, heated and evacuated by an exhaust vacuum pump 21 ′. The valve 8 of the gas supply line 4 to “opens” and the inert gas is supplied into the batch heat treatment furnace 1 ′ via the connection line 2 ′. At this time, when the atmospheric gas is introduced into the heat treatment furnace, since the inside of the furnace is in a high vacuum, the gas is supplied into the furnace by negative pressure without requiring power.

  After the heat treatment is completed, the inert gas in the heat treatment furnace 1 ′ is again collected in the buffer tank 12 and the purification tank 17 by following the procedure for collecting the inert gas shown in FIG. 2 described above.

  In the above-described embodiment, a set of two batch-type heat treatment furnaces is installed, and the inert gas is recovered and reused by a single system gas recovery and supply line. It is also possible to increase the number of pipelines in parallel and target three or more batch heat treatment furnaces.

According to the present invention, not only can the inert gas that forms the atmosphere of the batch-type heat treatment furnace, for example, argon gas, be reused, but also the waste inert gas from multiple furnaces can be efficiently recovered and reused to reduce the heat treatment cost. Reduction can be achieved.
Further, although the inert gas itself is not toxic, it is possible to eliminate the risk of oxygen deficiency caused by, for example, argon gas heavier than the average molecular weight of air staying in a pit in a factory.
Therefore, the present invention has high applicability in the steel industry.

DESCRIPTION OF SYMBOLS 1, 1 'Batch type heat treatment furnace 2, 2' Connection pipe line 3 Gas recovery pipe line 4, 4 'Gas supply pipe line 5 Vacuum pump 6 Compressor pump 7 Dust removal device 8, 8', 9, 9 ', 10, 11 , 14, 15, 16, 19, 19 ′ Valve 12 Buffer tank 13 Purification device 17 Storage tank 18 Inert gas recovery and reuse device 20 Titanium strip coil 21, 21 ′ Vacuum pump for exhaust

Claims (5)

A plurality of batch-type heat treatment furnaces containing heat treatment objects made of titanium or titanium alloy materials are installed, and the inert gas forming the atmosphere in one of the batch-type heat treatment furnaces is dedusted and radiated after the heat treatment is completed. collected in the buffer tank was installed mechanism is reused as atmosphere forming gas in the furnace after purification purity more than 99%, the other batch heat treatment furnace using a recovered inert gas to cryogenic separation method A method for recovering and reusing an inert gas after heat treatment. 2. The method for recovering and reusing an inert gas according to claim 1, wherein the heat treatment object is a titanium strip coil. A plurality of batch type heat treatment furnace containing a heat-treated object made of titanium or a titanium alloy material, and a vacuum pump for recovering the connecting line a through inert gas from the plurality of batch-type heat treatment furnace, non recovered A dust removing device for filtering active gas, a buffer tank provided with a heat dissipation mechanism, a compressor pump, a purifying device for purifying the collected and dusted inert gas to a purity of 99% or more, and storing the purified inert gas A storage tank, and the vacuum pump to the storage tank are connected in this order by a pipe line with a valve interposed therebetween to form a gas recovery pipe line, from the storage tank to each of a plurality of batch-type heat treatment furnaces. , coupled with conduit interposed valve, a gas supply line, characterized in that connected to the vacuum pump respectively at connecting pipeline to the plurality of batch-type heat treatment furnace Netsusho Recovery and reuse system of the inert gas after. Claim 3, characterized in that a inert gas recovery amount measuring device to the gas collection pipe
Recovery and reuse system of the inert gas after the heat treatment according to. The apparatus for collecting and reusing an inert gas after heat treatment according to claim 3 or 4, wherein the buffer tank and the storage tank are provided with means for measuring the amount of gas pressure and the purity thereof.

Images