JPS6352085B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for continuous heat treatment of metals.

Heat treatment of metals, for example, as a means of sintering molded products of metal powder or brazing them or molten materials, the preheating section or dewaxing section (hereinafter referred to as the preheating section)
and main heating section or sintering section (hereinafter referred to as main heating section)
A commonly used tunnel-type heating furnace has a structure in which a predetermined atmosphere is supplied to the two, and the workpiece is heat-treated while being continuously transported by a conveyor belt or pusher.

However, in such tunnel-type continuous furnaces, there is an increasing demand for energy saving and resource saving, and one measure to achieve this is to install a combustion burner in the preheating section, and use this combustion burner to emit less than the theoretical amount of air. Conventionally, a method has been used in which a heavy hydrocarbon gas is combusted using a heat exchanger, the generated combustion gas is sprayed onto a workpiece to heat it, and then the workpiece is heated in a main heating section using an electric heater or the like in a predetermined atmosphere.

This gas combustion preheating method is more effective in reducing power consumption and promoting burn-off of the lubricant than a method in which both preheating and main heating are performed using electric heat. however,
In the above method, the preheating atmosphere is the hydrocarbon combustion gas itself and contains a large amount of H ₂ O and CO ₂ , so while the dewaxing effect is good, the material to be treated is easily oxidized due to the above components, so the next step There is a problem in that decarburization is promoted in the main heating section, making it impossible to obtain the desired good quality product, and this problem becomes more noticeable when the heating temperature in the preheating section is raised to increase the dewaxing effect.

In addition, in the above method, the combustion gas is directly heated using a combustion burner, and the combustion gas is dissipated into the atmosphere from the inlet of the preheating section, so a separate atmosphere gas generator is used to generate metamorphosed gas such as heavy hydrocarbon gas. This has to be introduced into the main heating section, which increases equipment cost and wastes a lot of gas.Furthermore, as mentioned earlier, a large amount of H ₂ O and CO ₂ must be introduced into the preheating section. Combustion gas containing This method has the disadvantage that there is a large loss of gas consumption and heat because gas must be introduced.

The present invention aims to solve the problems of the conventional heat treatment method using gas combustion and heating.
The purpose of this is to greatly reduce the consumption of atmosphere raw material gas and the required amount of heat, and also to save energy and resources by being able to freely control the atmosphere composition to match the material properties of the workpiece, making it easy to manage the atmosphere. An object of the present invention is to provide a method for heat treating a mold.

In order to achieve this object, the present invention provides a method for performing heat treatment in a tunnel-shaped furnace in which a preheating section and a main heating section are connected, in which a mixed gas of hydrocarbon gas and air is combusted outside the matsufuru of the preheating section. While preheating the object, the combustion gas that has preheated the object to be treated is guided outside the furnace, cooled and dehydrated, and then preheated. Hydrocarbon gas is added to this gas to transform it and adjust it to an endothermic gas with a predetermined composition, which is then sent to the main heating section. In the supply and preheating section Matsufuru,
The structure is such that either the dehydrated combustion gas, a mixed gas of this and an endothermic gas, or a mixed gas obtained by adding combustion gas before cooling to this mixed gas is supplied.

Another object of the present invention is to provide an apparatus suitable for carrying out the above heat treatment method.

In order to achieve this object, the present invention includes a preheating section in which a matzuru is inserted inside a combustion burner, and a furnace body that communicates with the preheating section and has a heater therein, and the preheating section has a main body that communicates with the outside of the matzuru. An exhaust system is installed, a heat exchanger and a cooler are installed in this exhaust system,
The outlet side of the cooler is inserted into the heat exchanger and then branched to form a first furnace air introduction system that communicates with the inside of the furnace main body on one side, and a second furnace air introduction system that communicates with the inside of the Matsufuru on the other side. A shift heater is interposed in the first furnace air introduction system, and an enrichment gas supply system is connected to the inlet side of the shift heater via a flow rate regulating valve. The outlet side of the shift conversion heater of the air introduction system is branched and connected to the second introduction system.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the continuous heat treatment method for metal according to the present invention, in which 1 is a preheating section, 2 is a main heating section connected directly to the preheating section 1 or via a connecting tube, and 3 is a main heating section 2. A cooling section 4 connected to the cooling section 4 is a replacement chamber provided as necessary, and is configured in a series of tunnels from the preheating section 1 to the cooling section 3 or replacement chamber 4, and is connected to a feeding means 5 such as an endless conveyor or pusher. This allows the objects to be processed to be sequentially processed. Then, a heating heater 6 is installed in the main heating section 2.
In addition, several combustion burners 7 are inserted in the preheating section 1.

When heat-treating the workpiece A in such a tunnel-shaped continuous heating furnace, the present invention is to insert a Matsufuru 8 inside the combustion burner 7 of the preheating section 1, so that the tip of the Matsufuru 8 is inserted. is the charging port. The matsufuru 8 may be stopped at the front wall of the main heating section 2, but may be passed through the inside of the main heating section 2 if the heat treatment temperature is not high. and,
During operation, a mixture of hydrocarbon gas (CmHn) G ₁ and air G ₂ is supplied to the combustion burner 7 and is combusted in the outer space 9 of the preheating section 1 . At this time, in the conventional heating method, incomplete combustion was achieved by using less than the stoichiometric amount of air, but in the present invention, complete combustion is achieved by controlling the air/raw material ratio to a state equivalent to almost stoichiometric combustion. As a result, the temperature of the workpiece A is heated through the matsuru 8, dewaxing progresses during sintering, and preheating progresses during brazing.

However, in the conventional heating method, the combustion gas is directly released from the preheating section 1 to the atmosphere, and the main heating section 2
However, in the present invention, the gas _G3 combusted in the combustion burner 7 is first supplied to the outside from the Matsufuru outer space 9 without being released into the atmosphere as described above. This combustion gas G ₃ is cooled by a cooler 11, and a certain amount of moisture in the gas is removed by an auto drain.

Next, the dehydrated combustion gas G ₄ is weighed and preheated to an appropriate temperature by heat exchange with the following combustion gas G ₃ , and a predetermined amount of hydrocarbon G ₁ ' is added to the preheated dehydrated combustion gas G ₄ to enrich it. , this mixture is supplied to the transformation heater 12 and heated to undergo transformation. In the metamorphosis step, the dehydrated combustion gas
By adjusting the amount of hydrocarbon gas G ₁ ' added to G ₄ , the specified composition is adjusted to suit the atmosphere required for the main heating section 2, and the endothermic gas (EN Gas) _G5 is introduced into the main heating section 2, and the preheated workpiece A is heated using this as furnace air to perform main sintering or brazing.

The furnace air in the main heating section 2 is configured as described above, and in parallel with this, a part of the combustion gas G ₄ extracted from the preheating section 1 and cooled and dehydrated is transferred to the Matsufuru 8 of the preheating section 1. At this time, by adding and mixing an appropriate amount of endothermic gas _G5 obtained in the previous enrichment-transformation process to the dehydrated combustion gas, the atmosphere in the preheating section can be adjusted to match the properties of the material to be treated. The ingredients are adjusted to meet the conditions such as physical properties. Note that, if necessary, it is also possible to adopt a mode in which the combustion gas _G3 drawn out from the outside of the Matsufuru in the preheating section 7 is also added to the above gas and introduced into the Matsufuru.
Therefore, according to the present invention, it is possible to freely and easily control the atmosphere introduced into the preheating section over a wide range from exothermic gas (EX) to endothermic gas EN. This is advantageous when the heat treatment to be performed is sintering, and it is possible to carry out a very effective dewaxing process that is responsive to the material of the powder.

Next, the above invention will be compared with the conventional method to examine its effects.

Taking C ₄ H ₁₀ as an example of hydrocarbon gas, in the case of the present invention, the following chemical reaction occurs in the preheating section 1 by the combustion burner 7.

2C ₄ H ₁₀ +13O ₂ +49N ₂ →8CO ₂ +10H ₂ O + 49N ₂ As a result, a calorific value of +636 kcal/mol is obtained for C ₄ H ₁₀ , and the object to be treated is preheated or dewaxed with this calorific value. By cooling the combustion gas extracted from the preheating section 1, H ₂ O is approximately removed, resulting in a gas containing 8CO ₂ +49N ₂ . In the present invention, this material is preheated and then enriched with C ₄ H ₁₀ gas for transformation. At this time, the following reaction occurs in the transformation furnace.

2C ₄ H ₁₀ +8CO ₂ +49N ₂ →16CO + 10H ₂ +49N _2The present invention introduces the gas resulting from this reaction as the furnace air of the main heating section 2, and also introduces the gas alone or by dehydrating the combustion gas from the preheating section. was given
A mixture of 8CO ₂ +49N ₂ gases is introduced as the atmosphere in the preheating section 1.

When comparing the amount of gas consumed between the method of the present invention and the conventional method as described above, the transformation reactions in the method of the present invention and the conventional method are as follows.

Equation (1) is the present invention, Equation (2) is the conventional method, and (1)
Comparing Equation and Equation (2), we get the following.

Therefore, according to the present invention, the amount of hydrocarbon gas consumed as a raw material for converted gas is reduced to 44% compared to the conventional method, which is extremely economical.

Next, when considering the heat balance of the method of the present invention and the conventional method, in the case of equation (1), for C ₄ H ₁₀ -195kcal/
mol, and in the case of formula (2), + for C ₄ H ₁₀
It is 76kcal/mol. Therefore, if we are to generate 16.5 m ³ /H of metamorphosed gas, in the conventional method, the consumption of C ₄ H ₁₀ is 1 m ³ /H from equation (2), and the amount of heat generated is 44.6 mol × 76 kcal / mol = 3390 kcal. /H. On the other hand, the amount of heat required to warm the raw material gas is
If the specific heat is 0.33kcal/ ^m3 , it is -5445kcal/H, and the total is -2055kcal/H, which means that this amount of heat must be given.

On the other hand, in the method of the present invention, the amount of C ₄ H ₁₀ consumed is 0.44 m ³ /H from equation (1), so the required amount of heat is
19.6mol×-195kcal/mol=-3822kcal/H, and the amount of heat required to warm the raw material gas is -
It is 5445kcal/H. However, the present invention uses combustion gas generated in the preheating section as most of the raw material gas for shift conversion, and the calorific value of complete combustion of C ₄ H _{10 of} 0.44 _m ³ /H is approximately Since it is 636kcal/mol, it becomes 12466kcal/H, so the total is
It becomes 3199kcal/H. This has a large gain in terms of heat quantity compared to the conventional method.

Next, an embodiment of the heat treatment apparatus according to the present invention will be described. It is as shown in FIGS. 2 to 4.
2 is a preheating section in which a combustion burner 7 is inserted into the side wall of the refractory or the upper wall if necessary; 2 is the main heating section (furnace body) in which a heater 6 is installed inside the refractory; A matzuru 8 is inserted inside the combustion burner 7. In this embodiment, the Matsuful 8
is also inserted through the main heating section 2, but depending on the heating conditions, the main heating section 2 may be an airtight outer shell type furnace body without using a matzuru.

Reference numeral 13 denotes an exhaust port provided on the bottom wall of the preheating section 1. An exhaust system 14 is connected to the exhaust port 13, and a heat exchanger 10 and a cooler 11 are connected in series to the exhaust system 14. and the heat exchanger 10
and cooler 11 are provided with drain pipes 15 and 16, respectively. A flow meter 17 is interposed in the exhaust system 14 on the outlet side of the cooler 11, and a bent flow path 18 is formed to be inserted into the heat exchanger 10. It is branched into two systems, one of which is configured as a first furnace air introduction system 19 that communicates with the main heating section 2, and the other is a second furnace air introduction system 2 that communicates with the inside of the preheating section 1.
It is 0. Reference numeral 21 denotes a gas introduction pipe connected to the first furnace air introduction system 19, which is inserted into the Matsufuru and blows out furnace air from a group of small holes at its tip. Reference numeral 22 denotes a gas introduction pipe connected to the second furnace air introduction system 20, and is provided at an intermediate position between the preheating section 1 and the main heating section 2.

A shift heater 23 is interposed in the first reactor air introduction system 19 and includes an inner cylinder 231 filled with a catalyst such as generalite and a heater 232 around the inner cylinder 231. 23, an enrichment gas supply system 24 is connected to the flowmeter 2.
5 is connected via a shutoff valve 26 and an automatic flow rate control valve 27, and an arbitrary amount of enrichment gas is supplied depending on the flow rate of dehydrated combustion gas flowing into the first reactor air introduction system 19, that is, the amount of gas inserted into the preheating section. It is added and supplied to the shift conversion heater 23. and,
The second reactor air introduction system 2 is connected to the outlet side of the shift conversion heater 23 via a flow meter 28 and a regulating valve 29.
The mixing system 30 connected to 0 is branched. Further, another mixing system 31 branched from the inlet side of the heat exchanger 10 is connected to the second furnace air introduction system 20 via a regulating valve 32 .

Note that the configuration shown is such that the combustion gas in the preheating section 1 is pushed into the system, but instead of this, a pump may be provided at an appropriate location in the system to perform suction and pushing. Further, a proportional mixer may be interposed near the connection between the first reactor air introduction system 19 and the enrichment gas supply system 24.

To explain the situation in which the present invention is carried out using the above-mentioned apparatus, a mixture of hydrocarbon gas and air is completely combusted by the combustion burner 7 in the preheating section 1, and the object A to be treated is thereby indirectly heated through the matzuru 7.
On the other hand, the combustion gas is taken out from the outer periphery of the matsuful 7 through the exhaust inlet 13 to the exhaust system 14, and is cooled by a heat exchanger 10 and a cooler 11 in this system. At this time, the moisture in the combustion gas is removed from the drain pipe 1.
5 and 16, a certain amount is removed. Next, the combustion gas that has passed through the cooler 11 is measured by a flow meter 17 and passed through a bent flow path 18 inserted into the heat exchanger 10.
It is preheated by heat exchange with the following combustion gas.

In this way, the preheated dehydrated combustion gas is
A part of it is supplied from the gas introduction pipe 22 to the Matsufuru of the preheating section 1 through the second furnace air introduction system 20,
The remaining dehydrated combustion gas is sent to the enrichment gas supply system 24.
The gas is mixed with hydrocarbon gas supplied from the converter and converted in the converter heater 23. The component composition of the converted gas at this time can be freely adjusted by controlling the opening of the flowmeter 25 and automatic flow rate adjustment valve 27, and the first furnace is used as an endothermic gas with a predetermined component that matches the processing conditions. From the air introduction system 19 to the main heating section 2
Continuously supplied.

At that time, a part of the gas is sent from the first reactor air introduction system 19 to the second reactor air introduction system 20 by the mixing system 30, and is supplied into the Matsufuru in a state mixed with the previous dehydrated combustion gas. Ru. The amount of the endothermic gas added can be freely controlled using the flow meter 28 and the flow rate adjustment valve 29, and by simultaneously operating the adjustment valve 32 of the other mixing system 31,
It is also possible to add a gas containing a large amount of H ₂ O or CO ₂ . Of course, it is also possible to close the adjustment valves 29, 32, 33 so that the furnace air is not supplied to the Matsufuru 8 of the preheating section 1, and furthermore, open the adjustment valves 29, 32 of the mixing system to It is also possible to supply mixed gas to Matsufuru. Therefore, according to the apparatus of the present invention, it is possible to freely adjust the atmosphere in the preheating section 1 to the optimum composition depending on the physical properties of the object to be treated, the purpose of heat treatment, etc.

According to the present invention as described above, in a method for continuous heat treatment of metal using a gas-fired tunnel heating furnace in the preheating section, only the combustion heat of hydrocarbon gas is used in the preheating section, and the object to be treated and the combustion gas are heated. It is isolated by a matzuru, and inside the matzuru, there is a gas obtained by dehydrating the combustion gas, a mixed gas with an endothermic gas enriched with hydrocarbons, or a combustion gas before cooling is added to this mixed gas. By introducing a mixed gas that is It becomes possible to sufficiently cope with the rise in temperature. Furthermore, the complete combustion gas in the preheating section is used, and after being dehydrated and preheated, hydrocarbon gas is enriched and transformed and introduced into the main heating section as an endothermic gas, which greatly reduces the consumption of atmospheric raw material gas and the amount of heat. This makes it possible to appropriately save resources and save energy. In addition, since dehydrated gas or a mixed gas of this and endothermic gas is introduced into the preheating section,
Unlike conventional methods of this type, gas containing large amounts of H ₂ O and CO ₂ does not enter the main heating section.
The atmosphere in the main heating section can be maintained well,
Excellent effects such as being able to perform heat treatment under low dew point conditions can be obtained.

Further, according to the second aspect of the present invention, it is possible to provide an apparatus suitable for carrying out the method of the present invention, and in particular, by inserting the exhaust system on the outlet side of the cooler into a heat exchanger, combustion gas can be easily cooled. The dehydrated combustion gas can be preheated, and the first reactor air introduction system and the second reactor air introduction system are branched off at the outlet side of the cooler, and the second reactor air introduction system and the converter heater and later are separated. Since the first furnace air introduction system is connected to the first furnace air introduction system, excellent effects such as being able to easily and freely adjust the atmosphere introduced into the preheating section from exothermic gas to endothermic gas can be obtained.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the principle of the continuous heat treatment method for metals according to the present invention, FIG. 2 is a sectional view showing an embodiment of the continuous heat treatment apparatus for metals according to the present invention, and FIG. 3 is the diagram shown in FIG. FIG. 4 is a sectional view taken along the lines of FIG. 2. 1... Preheating section, 2... Main heating section, 7... Combustion burner, 8... Matsufuru, 10... Heat exchanger, 11
... Cooler, 14 ... Exhaust system, 19 ... First reactor air introduction system, 20 ... Second reactor air introduction system, 23 ...
Shift conversion heater, 24...Enrichment gas supply system, 30, 31...Mixing system, _G1 , _G1 '...Hydrocarbon gas, _G2 ...Air, _G3 ...Combustion gas, _G4 ... …
Dehydrated combustion gas, G ₅ ... metamorphosed gas.

Claims (1)

[Claims] 1. A method of performing heat treatment in a tunnel-shaped furnace in which a preheating section and a main heating section are connected, in which a mixed gas of hydrocarbon gas and air is combusted outside the matsufuru of the preheating section to preheat the object to be treated. On the other hand, the combustion gas that has preheated the object to be treated is guided outside the furnace, cooled and dehydrated, and then preheated, hydrocarbon gas is added to this gas to transform it, adjust it to an endothermic gas with a predetermined composition, and supply it to the main heating section. and a metal characterized in that the preheating part Matsufuru is supplied with either the combustion gas after dehydration, a mixed gas of this and an endothermic gas, or a mixed gas obtained by adding combustion gas before cooling to this mixed gas. continuous heat treatment method. 2. The combustion burner is equipped with a preheating section in which a Matsufuru is inserted, and a furnace body that communicates with the preheating section and has a heater inside, and the preheating section is provided with an exhaust system that communicates with the outside of the Matsufuru, and heat is supplied to the exhaust system. An exchanger and a cooler are provided, and the outlet side of the cooler is inserted into the heat exchanger and then branched to form a first furnace air introduction system that communicates with the inside of the furnace main body, and the other conducts into the inside of the Matsufuru. A second reactor air introduction system is provided in which a shift heater is interposed in the first reactor air introduction system, and an enrichment gas supply system is connected to the inlet side of the shift heater via a flow rate regulating valve. A continuous heat treatment apparatus for metal, which is connected to the first furnace air introduction system, and further has an outlet side of a converting heater of a first furnace air introduction system branched and connected to the second introduction system.