JPS61235680A - Reducing heat treatment furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reducing heat treatment furnace, and more particularly to a heat treatment furnace that is heated in a reducing atmosphere mainly containing hydrogen gas. Furthermore, the heat treatment furnace referred to here is
Not limited to a heat treatment furnace in the narrow sense, it refers to a furnace that processes or processes materials by storing and heating them in the furnace, and includes sintering furnaces and various heating furnaces that sinter powders such as iron and copper metals. etc.

[Prior art]

For example, when sintering pure metal or alloy powders such as iron, copper, and superalloys, oxidation of the powder surface is a particular problem, so a sintering furnace with a reducing atmosphere or neutral atmosphere is used. . The atmosphere used is hydrogen gas, decomposed ammonia gas, a single hydrocarbon gas such as propane, butane, or methane, or a mixture of these gases and air. Among these gases, hydrogen gas has a wide explosive range of 4.1% to 74.2% when mixed with air, which is wider than other types of flammable gases, and special care must be taken when handling it.

Therefore, in conventional sintering furnaces with hydrogen gas atmosphere,
Before creating a hydrogen gas atmosphere in the furnace, an inert gas such as nitrogen gas is first introduced into the furnace to reduce the amount of oxygen, and then hydrogen gas is introduced to create a reducing atmosphere.

However, even in such a sintering furnace, if the hydrogen gas in the hydrogen gas pump runs out and the supply of hydrogen gas to the furnace stops, the sintering furnace will no longer be pressurized and outside air will enter the furnace. However, there was a problem in that it could reach the explosion range and cause an explosion. In addition, a similar problem will occur if the hydrogen gas supply is stopped due to an unexpected situation such as an electrical problem or earthquake, and the solenoid valve installed in the hydrogen gas supply path will cause a similar problem. unmanned operation was impossible.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned conventional problems, and the present invention automatically replaces the atmosphere in the furnace with an inert gas when the supply of hydrogen gas to the furnace is stopped. It is intended to serve as a trap for reducing heat treatment furnaces.

[Structure of the invention]

The reducing heat treatment furnace of the present invention is a heat treatment furnace in which a hydrogen gas supply route and a replacement inert gas supply route are connected so as to heat in a reducing atmosphere mainly containing hydrogen gas. A pressure detection means for detecting the supply pressure is provided in the inert gas supply path, and a valve for supplying inert gas into the furnace in the inert gas supply path is opened in response to a signal from the pressure detection means; The present invention is characterized in that when the pressure in the hydrogen gas supply path becomes low, inert +'t gas is automatically supplied into the furnace to replace the hydrogen gas.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment applied to the sintering furnace according to item 1 of the present invention will be described below with reference to the drawings. A gas inflow pipe 2 and a gas discharge pipe 3 are provided in a pine tree that accommodates sintered material and is charged into a sintering furnace main body (not shown).

This Matsufuru 1 constitutes a part of a sintering furnace.

A gas supply pipe 5 is connected to the gas inflow pipe 2 via a flexible pipe 4, and a hydrogen gas supply pipe 6 is connected to the gas supply pipe 5.
and inert gas supply line 7 and safety inert gas supply line 1
0 is connected.

The hydrogen gas supply path 6 is connected from a hydrogen gas cylinder 60 to a neck hull pro 1, a pressure reducing valve 62, and a knob valve 63.
, a secondary pressure reducing valve 64, a ball hull pro 5, a flow meter 66, and a solenoid valve 67, and are connected to the gas supply pipe 5.

The inert gas supply passage 7 is branched halfway into an argon gas supply passage 8 and a nitrogen gas supply passage 9, and the argon gas supply passage 8 is connected to an argon gas cylinder from 80 to a neck valve 8.
1. After passing through the secondary pressure reducing valve 82, the stop valve 83, the secondary pressure reducing valve 84 and the ball valve 85, the nitrogen gas supply path 9 is connected to the nitrogen gas cylinder from 90 to the neck valve 91, the secondary pressure reducing valve 92, and the stop valve 93. , a secondary pressure reducing valve 94 and a ball valve 95, the gases merge together, and are connected to the gas supply pipe 5 via a filter 75, a flow meter 76, and a solenoid valve 77. Said safety inert gas supply path 1
0 is branched from the middle of the nitrogen gas supply path 9, that is, between the stop valve 93 and the secondary pressure reducing valve 94, and is connected to the pressure reducing valve 14,
It is connected to the gas supply pipe 5 via a ball valve 15 and a solenoid valve 17. The solenoid valve 17 is of a type that is closed when the power is turned on and opened when the power is turned off, contrary to a normal solenoid valve. Further, this solenoid valve 17 includes a pressure switch 18 as a pressure detection means interposed between the ball valve 65 of the hydrogen gas supply path 6 and the flow meter 66.
When the pressure drops below the set value, the solenoid valve 17
is configured to open. Furthermore, this solenoid valve 17
A seismic relay 19 is connected to.

The gas discharge pipe 3 of the Matsufuru 1 is connected to a combustion discharge pipe 20 via a flexible pipe 12, and is configured such that a viroft burner line 21 and an igniter 22 face the tip thereof.

In the above configuration, in order to perform the sintering process, first transport the 60 into the hydrogen gas cylinder stored separately for safety, connect it and check for leaks, then place the material into the manifold 1, and then Matsufuru 1 is charged and installed in a heating chamber of a sintering furnace body (not shown) using a lifter (not shown). Next, the neck valve 91, secondary pressure reducing valve 92, stop valve 93, and ball valve 95 of the nitrogen gas supply path 9 are sequentially closed. In addition, secondary pressure reducing valve 94, 84, 64, 14
is set to a predetermined pressure in advance and is open. Next, the electromagnetic valve 77 is opened and the flow rate is set to a predetermined value using the flow meter 76, and nitrogen gas is introduced into the matsufuru 1 for a predetermined period of time, for example, one hour, to replace the air within the matsufuru 1 with nitrogen gas. After that, before introducing hydrogen gas, the pyrosotoharna line 21 is activated and the igniter 2 is activated.
2 to ignite the hydrogen gas released from the combustion discharge pipe 20, and then connect the neck hull pro 1, -next pressure reducing valve 62, stop hull pro 3, and ball hull pro 5 of the hydrogen gas supply path 6. are sequentially opened, the flow rate is set to a predetermined value using the flow meter 66, and hydrogen gas is introduced into the Matsufuru l. Further, the ball valve 15 is opened to make the safety inert gas supply path 10 operable. In this state, the sintering furnace main body is heated and heated for a predetermined time according to a predetermined program to sinter the material. Thereafter, the above-mentioned valves are operated to introduce nitrogen gas into the manifold 1 again, and the hydrogen gas supply path 6 is operated to stop the supply of hydrogen gas.
Operate each valve. After introducing nitrogen gas for a predetermined period of time to replace the hydrogen gas in the Matsufuru 1 with nitrogen gas, all valves are closed, the Matsufuru 1 is taken out, and the sintered material is taken out from the Matsufuru 1.

During this time, if the hydrogen gas in the hydrogen gas pump 60 runs out, the hydrogen gas supply pressure will drop, so the pressure switch 18 will detect this and the safety inert gas supply path 10 will be
The solenoid valve 17 is opened, nitrogen gas is introduced into the matsuful 1, and the hydrogen gas is sequentially replaced with nitrogen gas. As a result of measuring the substitution ratio, at least 3 of the volume of Matsuful 1
It has been found that if the gas is vented twice, preferably five times or more, the hydrogen gas will be less than 4%, which is below the explosive range, and therefore safe. Further, the solenoid valve 17 is opened even if the power is cut off, and in the case of an earthquake, the solenoid valve 17 is also opened by a signal from the seismic relay 19, so it is as safe as the above.

To give a specific example, 10 kg of iron powder is set in a Matsufuru, and nitrogen gas is applied at a rate of 5,001 kg per the volume of the Matsufuru, 100β.
After venting, then switching to hydrogen gas and raising the temperature to 1000°C, firstly, if the ball hull pro 5 of the hydrogen gas supply path 6 is closed, secondly, if the power is turned off, and thirdly, if there is an earthquake, etc. In each case, the electromagnetic valve 17 of the safety inert gas supply path 10 opened and nitrogen gas was introduced into the Matsufuru.

After introducing nitrogen gas, the lid of the Matsufuru was opened, but no problems occurred.

〔Effect of the invention〕

According to the reducing heat treatment furnace of the present invention, a pressure detection means for detecting the supply pressure is provided in the hydrogen gas supply path for supplying hydrogen gas into the furnace, and a pressure detection means for detecting the supply pressure is provided as shown in -F below. The valve that supplies inert gas into the furnace is configured to open in response to a signal, so if the supply of hydrogen gas decreases or stops due to some abnormality, inert gas can be automatically introduced into the furnace. By replacing the hydrogen gas in the furnace with inert gas, the hydrogen gas concentration can be brought below the explosive range, ensuring safety. Therefore, there are effects such as enabling unmanned operation.

[Brief explanation of the drawing]

The figure is a piping system diagram of one embodiment of the present invention. 6 is a hydrogen gas supply path, 7 is an inert gas supply path (13°10
is an inert gas supply path for safety, 17 is an electromagnetic switch ↑, and 18 is a pressure switch.

Claims (1)

[Claims] 1. In a heat treatment furnace in which a hydrogen gas supply path and a replacement inert gas supply path are connected so that heating is performed in a reducing atmosphere mainly composed of hydrogen gas, the supply pressure is detected in the hydrogen gas supply path. A heat treatment furnace characterized in that a pressure detection means is provided, and a valve for supplying inert gas into the furnace in the inert gas supply path is opened in response to a signal from the pressure detection means.