JPH0512278Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an organic fluid supply device for a heat treatment furnace. More specifically, the present invention relates to an organic fluid supply device that continuously supplies an organic fluid at a constant flow rate into a heat treatment furnace, thereby forming a stable carbon atmosphere in the heat treatment furnace.

[Prior art and its problems] Conventionally, in heat treatments such as carburizing or quenching, reducing gases generated by an endothermic reaction in which propane or butane is combusted with air using a catalyst have been used.

However, in recent years, a method has been developed in which a carbon atmosphere is created by introducing an organic fluid such as methanol and an inert gas such as nitrogen into a heat treatment furnace and mixing them. has been done.

By the way, methanol used in the above method has high water absorbency, and when it comes into contact with air, it easily absorbs moisture in the air. When the amount of water present in methanol used for heat treatment exceeds a certain level, it has a detrimental effect on carburizing, quenching, etc.
That is, water in methanol is decomposed by heat and generates oxygen, which adversely affects carburizing and quenching processes. This is especially a problem during the humid summer months.

Further, if the flow rate of methanol supplied into the furnace fluctuates, it will affect the carbon atmosphere inside the furnace, and as a result, the quality of carburized and quenched parts will be affected.

Therefore, when supplying an organic fluid such as methanol to a heat treatment furnace in the above method, it is necessary to propose a supply device that solves the following conditions, that is, the following problems. That is, (1) Methanol must be dry and pure, containing no water.

(2) Methanol must be supplied in a small amount, and a fixed amount must be stable and continuous.

(3) In order to ensure even lower cost and high mass productivity,
It is possible to supply to multiple heat treatment furnaces from one supply device.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an apparatus for supplying organic fluid to a heat treatment furnace. An inert gas supply source that purges the internal space with an inert gas at a predetermined pressure and prevents air from entering, a pump that pumps the organic fluid in the storage tank to the heat treatment furnace via a supply line, and the storage tank. a filter provided in the supply line between the pump and the pump to remove impurities contained in the organic fluid; and a first pressure regulating valve provided in the supply line to adjust the pressure of the pressurized organic fluid to a predetermined value. , an automatic flow control valve that is installed in the supply line downstream from the first pressure control valve and supplies the organic fluid to the heat treatment furnace at a constant flow rate, and a feedback line that branches off from the pump and returns to the storage tank. , a second pressure regulating valve that is installed in the feedback line and returns a portion of the organic fluid to the storage tank via the feedback line when the pressure of the organic fluid pumped from the pump exceeds a predetermined value; An organic fluid supply device comprising:

[Examples] Examples of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the structure of an organic fluid supply device according to an embodiment of the present invention. In the figure, 1 is a heat treatment furnace, 2 is a methanol storage tank that stores methanol, which is an organic fluid, and 3 is a nitrogen storage tank that stores liquid nitrogen.

Nitrogen gas is supplied to the upper space 5 of the methanol 4 in the methanol storage tank 2 through the nitrogen storage tank 3 and piping 6, and the atmosphere in the upper space 5 is purged to perform nitrogen sealing. This inactivates the upper space 5 and prevents atmospheric moisture from being absorbed by the stored methanol 4. The pressure of nitrogen gas supplied to this upper space 5 is 0.07Kg/cm ² G (760mm/H ₂ O)
This prevents nitrogen from dissolving into the methanol. If a large amount of nitrogen dissolves into methanol, it will cause problems in the flow rate control system, which will be described later.

The methanol 4 in the methanol storage tank 2 is
The water is pumped through a siphon pipe 7 to a pump 9 driven by a motor 8. siphon tube 7
A filter 11 is provided in the middle of the methanol to remove impurities from the methanol.

The methanol whose pressure has been increased by the pump 9 is pumped into the methanol supply line 13, but this supply line 13 is provided with a pressure regulating valve 12, and the methanol is increased to 9 kg/cm ² G by the pump 9, for example. The pressure of methanol is adjusted to the pressure set by the pressure regulating valve 12, for example, 5 kg/cm ² G, and then supplied to the downstream side. By the way, a feedback line 14 is provided between the pump 9 and the pressure regulating valve 12, which branches off from the supply line 13 and returns to the methanol storage tank, and this feedback line 14 is provided with a pressure regulating valve 15. has been done. This pressure regulating valve 15 functions as a pressure regulating valve and maintains the pressure on the primary side (upstream side) at 9 kg/cm ² G. When the pressure of methanol blown out from the pump 9 reaches 9 kg/cm ² G or higher, the valve opens and a part of the methanol is returned to the methanol storage tank 2 to keep the pump outlet pressure constant (9 kg/cm ² G). to be maintained.

The methanol supply line 13 is further equipped with a flow meter 1.
6 and an automatic flow rate control valve 17 are provided, the end of which is connected to an injector 18 attached to the furnace wall so as to inject methanol into the heat treatment furnace 1. Automatic flow control valve used here 1
7 is a combination of a flow rate orifice and a balance control valve, and the differential pressure generated at the orifice is applied to the diaphragm to operate the valve, and as a result, pressure fluctuations on the inlet side are prevented. The flow rate value as an output does not change regardless of the flow rate. That is, the pressure of the pressure regulating valve tends to decrease somewhat over time as a commonly used regulating valve has.
Further, it is the pump 9 that pumps methanol into the methanol supply line 13, and since the pump 9 operates with pulsations, some pressure fluctuations occur in the methanol being pumped during its operation. However, since the automatic flow control valve 17 having the above-mentioned characteristics is disposed at the end of the supply line 13,
Once the flow rate value is set, even if there are pressure fluctuations in the pump, methanol will be sent to the nozzle 18 at a stable flow rate.

In this embodiment, a backup pump 21 driven by a motor 19 is connected to the methanol supply line 13 in parallel with the pump 9. This reserve pump 21 is normally stopped. And between the pressure regulating valve 12 and the flow meter 16,
A pressure switch 22 is provided to detect the pressure of methanol flowing within the methanol supply line 13. When the pressure switch 22 detects that the pressure in the methanol supply line 13 has become lower than a predetermined value, it sends a signal to the control circuit 23. The control circuit 23 has a built-in delay timer, and after receiving the first signal from the pressure switch 22,
If no signal indicating that pressure has been restored is received from the pressure switch for, for example, 5 seconds, a signal is issued to stop motor 8 and start motor 19. Thereafter, methanol will be pumped by the pump 21. As described above, since a backup pump that can be operated by switching the pressure switch is provided, if an abnormality occurs in the pump 9 or the motor 8 that drives it and the predetermined amount of methanol cannot be delivered, the backup pump Since a predetermined amount of methanol will continue to be sent by
The carbon atmosphere inside the furnace will not change and the quality of the product will not be compromised. The reason why a delay timer is used in the control circuit is that, as mentioned above, there is pulsation in the operation of the pump, and if the fluctuation value momentarily increases for some reason, the auxiliary pump 2 is immediately activated.
This is to prevent it from being switched to 1. If the pressure is restored within a predetermined period of time, a signal from the pressure switch 22 indicating this will stop and reset the delay timer.

When the delay timer is activated, the delay timer is reset and starts counting again when the pump 9 is switched to the backup pump 21. If a signal indicating that the pressure has been restored is not inputted from the pressure switch 22 by the time a predetermined time elapses, for example, 5 seconds,
A signal is sent to motor 19 to stop its operation. In such a case, the cause of the pressure drop is not due to a failure of the motor or pump, but is due to liquid leakage in the methanol supply line, so the supply of methanol is stopped. If the methanol pressure is restored within a predetermined time, the delay timer stops counting in response to a signal from the pressure switch 22, and the motor 19 continues to drive the pump 21. Different from the above-described embodiment, a delay timer that starts counting in response to a start signal to the motor 19 may be provided separately.
If a fault in the motor 8 or the pump 9 is repaired, it is possible to switch over to the pump 9 again automatically or manually.

With the above configuration, a constant amount of methanol is always continuously supplied into the furnace 1, and a stable carbon atmosphere can be obtained. This will be explained in detail.

The injector 18 has a double structure consisting of an inner cylinder 31 and an outer cylinder 32. A furnace wall attachment portion 33 at one end of the outer cylinder 32 is attached in an airtight manner to an injector attachment hole 34 provided in the wall 1a of the furnace 1. The inner cylinder 31 is inserted and held in an airtight manner into a central hole of a cap 35 that closes off the other end 39 of the outer cylinder 32, and one end 37 of the inner cylinder 31 is inserted through the inner hole 36 of the outer cylinder 32.
is adapted to protrude into the interior of the furnace 1, a so-called hot zone 1b. The inner diameter of the outer cylinder 32 is the same as that of the inner cylinder 31.
A cylindrical space is formed between the two, and this space becomes a nitrogen gas flow path 38, which will be described later. A hollow nitrogen gas injection hole 41 is formed adjacent to the closed end 39 of the outer cylinder 32 and extends laterally to the internal hole 36 and communicates with the nitrogen gas flow path 38 . Although not shown broken in FIG. 2, the nitrogen injection hole 41 is connected to the nitrogen tank 3, and the cold nitrogen gas passes through the nitrogen gas injection hole 41 and the nitrogen gas passage 38 into the interior of the furnace 1. supplied to

The other end 42 of the inner cylinder 31 held by the cap 35 is connected through a pipe joint 43 to a pipe 44 of the methanol supply line described above and a nitrogen gas pipe 45 for purging described later. During the heat treatment, a valve (not shown) provided in the middle of the pipe 45 is closed. Then, as mentioned earlier, methanol is pumped to pump 9 or 21.
Automatic flow control valve 17, piping 44
The methanol is fed under pressure through a methanol passage 46 in the inner cylinder 31 and is injected from one end 37. While carburizing and quenching are being carried out in the furnace 1 and methanol is being injected, cold nitrogen gas is constantly supplied into the furnace 1 through the nitrogen gas passage 38, so that the methanol is cooled. is,
There is no thermal decomposition within the methanol passage 46.

That is, the furnace wall has a steep temperature gradient from about 30°C to 900°C from its outer surface to its inner surface. Therefore, if the pipe through which methanol flows is attached directly to the wall of the furnace, the methanol will thermally decompose as it passes through the thick part of the wall. When methanol decomposes at temperatures below 650°C, it generates soot consisting of carbon of the following formula:

2CH ₃ OH→C+CH ₄ +2H ₂ O This soot adheres to the injection port of the injector and blocks it, causing malfunction.

However, in this embodiment, when the methanol passes through the thick part of the furnace wall as described above, it is cooled by the cold nitrogen gas and does not decompose. The temperature reaches 900℃ only after it is injected into the furnace.
At that time, it decomposes as shown in the following equation to generate carbon monoxide which forms a carbon atmosphere.

CH ₃ OH→CO+2H ₂ Furthermore, in this embodiment, when the heat treatment in the furnace is completed, the methanol remaining in the injector can be discharged. When the heat treatment is completed, the supply of methanol or nitrogen gas into the furnace is stopped by closing the valve, but at that point, methanol that has not been injected from the injection port remains in the injector. Since the furnace walls are still warm, the methanol remaining in the injector decomposes and generates soot as described above. Therefore, in this embodiment, as soon as the supply of methanol is stopped, the valve provided in the piping 45, which had been closed until then, is opened and nitrogen gas flows into the injector, discharging the remaining methanol into the furnace. It has become possible to emit it into the body. This prevents soot from forming. It is possible to arrange not only one injector but also a plurality of injectors in one furnace.
In this case, if it is sufficient to control the amount of methanol supplied to the entire furnace,
One flow meter 16 for multiple injectors,
One automatic flow control valve may be provided. but,
If it is necessary to control the flow rate for each injector, each injector will be provided with one flowmeter and one automatic flow control valve. It is also possible to connect a plurality of furnaces to one methanol supply line and supply methanol to these simultaneously under the same or different conditions.

[Effects of the invention] As is clear from the above explanation, according to the invention, the upper space of the storage tank is sealed and inertized with an inert gas, and is further branched from the organic fluid supply line and returned to the storage tank. A pressure regulating valve is provided in the return line to allow impurity gas dissolved in the organic fluid to return to the storage tank, so that pure, dry organic fluid can be supplied. In addition, an automatic flow rate control valve is installed in the supply line in addition to the pressure control valve, so once the flow rate is set, a constant amount of organic fluid can be stably supplied despite pressure fluctuations on the input side such as pump pulsation. can do.
Therefore, the carbon atmosphere in the furnace is stably maintained at desired conditions, making it possible to perform good heat treatments such as carburizing and quenching.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention, and FIG. 2 is a sectional view showing the structure of an injector. 1... Furnace, 2... Storage tank, 9, 21... Pump, 12... Pressure regulation valve, 15... Pressure regulation valve, 16... Flow meter, 17... Automatic flow rate regulation valve,
18...Injector, 22...Pressure switch,
23...Control circuit, 31...Inner cylinder, 32...Outer cylinder.

Claims (1)

[Claims for Utility Model Registration] 1. An organic fluid supply device for supplying an organic fluid under pressure into a heat treatment furnace, comprising: a storage tank in which the organic fluid is stored; and an internal space of the storage tank above the organic fluid at a predetermined pressure. an inert gas supply source for purging with an inert gas and preventing intrusion of air; a pump for pumping the organic fluid in the storage tank to the heat treatment furnace via a supply line; a filter that is installed in the supply line between the pumps and removes impurities contained in the organic fluid; and a first pressure regulator that is installed in the supply line and adjusts the pressure of the pressurized organic fluid to a predetermined value. a valve; an automatic flow rate control valve disposed in the supply line downstream of the first pressure control valve and supplying the organic fluid to the heat treatment furnace at a constant flow rate; branched from the pump and connected to the storage tank; a feedback line that is provided in the feedback line and returns a portion of the organic fluid to the feedback line when the pressure of the organic fluid pumped from the pump exceeds a predetermined value; and a second pressure regulating valve for supplying organic fluid to the heat treatment furnace through which the organic fluid is returned to the storage tank. 2 A pressure provided between a backup pump connected in parallel with the pump, the first pressure regulating valve and the automatic flow rate regulating valve, and detecting the liquid pressure of the organic fluid transferred within the supply line. The organic fluid supply device according to claim 1, further comprising a switch, and a control circuit that controls the operation of the pump and the reserve pump according to a signal sent from the pressure switch. . 3. The organic fluid supply device according to claim 2, wherein the control circuit has a delay timer. 4. The organic fluid supply device includes an injector at the downstream end of the supply line, the injector penetrating the wall of the heat treatment furnace, and an inner cylinder defining a passage for the organic fluid; The organic fluid supply device according to claim 1, which has a double structure comprising an outer cylinder and an outer cylinder defining a coolant passage around the periphery. 5. Utility model registration claim 4, wherein the coolant is a low-temperature inert gas supplied into the heat treatment furnace.
The organic fluid supply device according to paragraph 1. 6. The organic fluid supply device according to claim 4, wherein the organic fluid passage of the injector is selectively connected to the inert gas supply source by opening and closing a valve.