JP2017116162A - Heating treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating treatment device capable of effectively utilizing heat by recovering heat in a cooling treatment of a treated object of high temperature discharged from a heating furnace.SOLUTION: In a heating treatment device 1 including a rotary kiln 2 having a burner for supplying hot air to heat a heated object at a high temperature, a water-cooled cooling machine 3 for cooling the treated object discharged from the rotary kiln 2, and a cooling water circulation circuit 5 for circulating and supplying the cooling water for the cooling machine 3 between the cooling machine and a water storage tank 4, the burner of the rotary kiln 2 is a gas burner 12 applying a natural gas as a fuel, and liquefied natural gas storage/vaporization equipment 8 having a liquefied natural gas storage tank 6 and a carbureter 7, is disposed near the gas burner. On the other hand, the cooling water circulation circuit 5 at a downstream side of the cooling machine 3, is connected to the carbureter 7 to vaporize the liquefied natural gas by hot water generated in accompany with the cooling treatment of the heated object of high temperature, to produce a natural gas as a fuel for the gas burner 12.SELECTED DRAWING: Figure 1

Description

  The present invention, for example, when reclaiming anhydrous gypsum from waste gypsum, when heating and purifying soil contaminated with oil, or when heavy metals contained in incinerated ash are volatilized and separated by heating, etc. The present invention relates to a heat treatment apparatus used when it is necessary to heat treat an object at a relatively high temperature.

  For example, when reclaiming type II anhydrous gypsum, which is a raw material for cement, from waste gypsum, when heating and purifying soil contaminated with oil or VOC, or when volatile separation of heavy metals contained in incineration ash is performed In such a case, it is necessary to heat each of the objects to be processed at a relatively high temperature of about several hundreds of degrees C. to several hundreds of degrees C. As the heat processing apparatus, for example, heating such as a rotary kiln having a burner for supplying hot air A furnace may be used. In addition, since the object to be processed that has been heat-treated at a high temperature in the heating furnace as described above has poor handleability as it is, for example, an appropriate cooler or the like is provided in the lower part of the discharge part of the heating furnace. In many cases, a high-temperature workpiece is cooled to an appropriate temperature that is easy to handle.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2013-150981), soil contaminated with oil, VOC, or the like is sequentially charged into two kilns, a preheating kiln and a heat treatment kiln, and is heated to about 600 ° C. However, while purifying the soil by volatilizing and decomposing the pollutants contained in the contaminated soil, an appropriate amount of water is directly sprayed and handled on the purified soil discharged at a high temperature. A device for heating and purifying contaminated soil having a substantially drum-shaped soil cooling device that cools to an easy temperature is described.

  Further, in Patent Document 2 (Japanese Patent Application No. 2014-205557), powdery waste gypsum is heat-treated in a countercurrent kiln to about 800 ° C., and waste gypsum in a dihydrate gypsum state is II. While reclaimed as a type anhydrous gypsum, the type II anhydrous gypsum discharged at a high temperature is put into a cooling machine having a substantially screw conveyor shape and supplied to a jacket portion covering the outer periphery of the cooling machine. A powder heat treatment apparatus is described in which the type II anhydrous gypsum is indirectly cooled to a temperature at which it can be easily handled with cooling water.

JP 2013-150981 A Japanese Patent Application No. 2014-205557

  However, immediately after the object to be processed is once heated to a high temperature in a heating furnace as in the above-mentioned conventional apparatus, it is merely a cooling process in the cooler due to the problem of its handling property. There is a lot of waste, and there is room for improvement in consideration of energy saving.

  In view of the above-described points, an object of the present invention is to provide a heat treatment apparatus that can be effectively used by performing heat recovery when cooling a high-temperature object to be discharged from a heating furnace.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive studies, and as a result, in recent years, natural gas, which emits less carbon dioxide during combustion than heavy oil or propane gas and has a relatively low environmental impact, For example, satellite-type LNG storage and vaporization facilities are becoming popular so that they can be used not only in urban areas where they are maintained, but also in areas where conduits are not sufficiently developed. Attention was paid to a certain point and the fact that the heating furnace of the heat treatment apparatus is equipped with a burner for supplying hot air using a large amount of fuel.

  In the liquefied natural gas storage / vaporization facility, at least a liquefied natural gas is stored at a low temperature of −162 ° C. or lower and under a high pressure, and the liquefied natural gas stored in the storage tank is vaporized by heat exchange. And a separate equipment such as a boiler is essential to generate hot water that is a heat source of the vaporizer. For example, a high-temperature object to be processed discharged from the heating furnace If the hot water generated during the cooling process is effectively used as a heat source for the vaporizer, heat recovery can be achieved, waste of heat energy can be suppressed, and energy saving can be expected. On the other hand, if the burner of the heating furnace is a gas burner using natural gas as a fuel, for example, the natural gas produced in the vaporizer is used as it is as the burner fuel. It is possible to reduce the environmental burden, and it will be useful for both the heat treatment device and the liquefied natural gas storage / vaporization facility, and it will be easy to adopt. It is a thing.

  That is, in the heat treatment apparatus according to claim 1 of the present invention, a heating furnace having a hot air supply burner for heat-treating the object to be processed at a high temperature, and the object to be processed discharged from the heating furnace are cooled. A heat treatment apparatus comprising a water-cooling type cooling machine and a cooling water circulation circuit that circulates and supplies cooling water for the cooling machine to and from a water storage tank, wherein the burner of the heating furnace is a gas burner using natural gas as fuel And a liquefied natural gas storage tank for storing at least liquefied natural gas under low temperature and high pressure, and a vaporizer for vaporizing the liquefied natural gas stored in the liquefied natural gas storage tank, in the vicinity of the heating furnace. While providing a liquefied natural gas storage / vaporization facility, a cooling water circulation circuit on the downstream side of the cooler is connected to the vaporizer of the liquefied natural gas storage / vaporization facility, and a high-temperature object is cooled by the cooler. Accompanying The hot water in the liquefied natural gas produced Te vaporization process to is characterized by being configured to produce a natural gas, a fuel for the gas burner.

  According to the heat treatment apparatus of the first aspect of the present invention, the burner of the heating furnace of the heat treatment apparatus is a gas burner using natural gas as fuel, and liquefied natural gas is placed near the heating furnace at low temperature and high pressure. A liquefied natural gas storage tank having a liquefied natural gas storage tank and a vaporizer for vaporizing the liquefied natural gas stored in the liquefied natural gas storage tank are provided together with the liquefied natural gas storage tank. A cooling water circulation circuit on the downstream side of the cooler is connected to the vaporizer of the vaporization facility, and the liquefied natural gas is vaporized with warm water generated as a result of cooling the high-temperature object to be the fuel for the gas burner. Since it is configured to generate natural gas, heat can be recovered and effectively used when a high-temperature object to be processed discharged from a heating furnace is cooled. In addition, boiler equipment for vaporizing low-temperature liquefied natural gas is not required, and the temperature of the hot water discharged from the cooler can be lowered by heat exchange with low-temperature liquefied natural gas. There is no need for cooling water cooling equipment required when circulating and supplying hot water to the cooler as cooling water again, or at least the required cooling capacity can be reduced, simplifying the equipment configuration and reducing the cost. Can be expected, and will be relatively easy to adopt. In addition, natural gas having a low environmental load can be easily used as the burner fuel for the heating furnace of the heat treatment apparatus, which is suitable in terms of the environment.

It is a schematic explanatory drawing which shows one Example of the heat processing apparatus which concerns on this invention.

  In the heat treatment apparatus according to the present invention, a heating furnace such as a rotary kiln having a hot air supply burner that heat-treats various objects to be processed at a high temperature, and a high-temperature object discharged from the heating furnace. A water-cooled cooler that cools the processed material to an appropriate temperature that is easy to handle, and a cooling water circulation circuit that circulates the cooling water for the cooler between adjacent water storage tanks are provided. The cooling machine is configured so that, for example, the cooling water is disposed on the outer periphery of the screw conveyor that feeds the processed material so that the high-temperature processed material can be indirectly cooled with the cooling water circulated and supplied from the cooling water circulation circuit. An indirect water-cooled chiller that is covered with a flowing down jacket is used.

  Further, the burner of the heating furnace is a gas burner using natural gas as fuel, and a liquefied natural gas storage tank for storing at least liquefied natural gas under low temperature and high pressure in the vicinity of the heating furnace, and the liquefied natural gas storage tank A satellite-type liquefied natural gas storage / vaporization facility having a hot water vaporizer that vaporizes the liquefied natural gas stored in the hot water by heat exchange with the hot water.

  Further, a cooling water circulation circuit on the downstream side of the cooler (discharge side when viewed from the cooler) is connected to the vaporizer of the liquefied natural gas storage / vaporization facility, and a high-temperature object to be treated is connected to the cooler. The hot water generated during the cooling process is supplied to the vaporizer, and the vaporizer uses the hot water as a heat medium to vaporize the low-temperature liquefied natural gas to produce the natural gas that is the fuel for the gas burner. It is configured to do. In the hot water type vaporizer, a heat transfer tube for passing a low-temperature liquefied natural gas into a container capable of temporarily storing hot water as a heat medium is provided, for example, in a substantially spiral shape, and is in contact with the hot water. The liquefied natural gas is efficiently vaporized by increasing the amount of gas, and can be stably supplied as fuel for the gas burner of the heating furnace.

  When heat-treating an object to be processed in the heat treatment apparatus having the above configuration, first, the gas burner provided in the heating furnace is burned and hot air is supplied into the furnace, and the object to be processed is supplied into the furnace. Heating to a predetermined temperature while exposed to hot air. The object to be processed that has been heated to a high temperature is eventually discharged from the heating furnace, sequentially put into a water-cooled cooler, and cooled to a temperature that is easy to handle with cooling water that is circulated and supplied from a water storage tank. On the other hand, the hot water generated by the cooling process is supplied to a vaporizer connected to a cooling water circulation circuit on the downstream side of the cooler, where the natural gas is generated by vaporizing the liquefied natural gas with the hot water. The produced natural gas is supplied as burner fuel to the gas burner of the heating furnace. Then, the hot water (cooling water) whose temperature is slightly lowered by heat exchange with the low-temperature liquefied natural gas in the vaporizer is cooled via a cooling tower, for example, a cooling tower, and then the water storage It is sent back to the tank and circulated and supplied again as a refrigerant to the cooler.

  Thus, in a heat treatment apparatus having a heating furnace that heat-treats the object to be processed at a high temperature, and an indirect water-cooled cooler that cools the object to be processed discharged from the heating furnace in a high-temperature state by the heat treatment, The burner provided in the heating furnace is a gas burner using natural gas as fuel, and a satellite-type liquefied natural gas storage / vaporization facility is provided in the vicinity of the heating furnace to cool the object to be processed by the cooler. The hot water generated by the treatment can be effectively used without waste as a heat source for the vaporizer of the liquefied natural gas storage and vaporization equipment, and heat recovery can be achieved, thereby preparing for the hot water generation of the vaporizer, which has been essential in the past. Natural gas with a relatively low environmental load generated in the vaporizer can be supplied as fuel for the gas burner as it is. Energy surfaces and cost, becomes useful and preferred in environmental like. Moreover, by using the hot water discharged from the cooler for heat exchange with the low-temperature liquefied natural gas, the temperature of the cooling water can be adjusted to be low, and it can be used for cooling water such as a cooling tower required for the cooling water circulation circuit. A cooling facility is unnecessary, or at least the required cooling capacity can be suppressed, and simplification of the apparatus configuration and reduction in cost can be expected.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the figure, reference numeral 1 denotes a heat treatment apparatus for heat-treating an object to be treated at a high temperature, a rotary kiln 2 that is a heating furnace, a water-cooled cooler 3 that cools the heated object to be treated, A cooling water circulation circuit 5 that circulates and supplies cooling water for the cooler 3 to and from the water storage tank 4, and liquefied natural gas that stores at least liquefied natural gas under low temperature and high pressure in the vicinity of the rotary kiln 2. A satellite-type liquefied natural gas storage / vaporization facility 8 having a storage tank 6 and a vaporizer 7 for vaporizing liquefied natural gas stored in the liquefied natural gas storage tank 6 is provided.

  The rotary kiln 2 is provided with a kiln main body 9 that is tiltably supported so as to be rotatable. An input chute 11 for injecting a workpiece through a hot hopper 10 at one end of the kiln main body 9 and a gas burner using natural gas as fuel. 12, an exhaust duct 14 is connected to the other end of the kiln main body 9 via a cold hopper 13, and a dust component contained in the exhaust gas is disposed downstream of the exhaust duct 14. A chimney 17 is disposed at the end of the bag filter 15 for collecting the dust and the exhaust fan 16 for exhaust gas exhaust.

  The cooler 3 is provided below the cold hopper 13 of the rotary kiln 2 through a discharge chute 18 for discharging the heat-treated object. The cooler 3 includes a screw conveyor 19 that sends out a high-temperature object to be processed and a jacket portion 20 that covers the outer periphery of the screw conveyor 19, and the high-temperature object to be discharged from the rotary kiln 2 is cooled. While being sent out by the screw conveyor 19 of the machine 3, cooling water is allowed to flow down to the surrounding jacket portion 20 so that the high temperature object can be indirectly cooled to an appropriate temperature that is easy to handle. The cooler 3 is not limited to the above structure. For example, the cooling water may be allowed to flow into a conduit formed in the screw shaft of the screw conveyor 19 instead of the jacket portion 20. May have an indirect water-cooled structure.

  The cooling water circulation circuit 5 can circulate and supply cooling water between the cooling machine 3 and a water storage tank 4 provided in the vicinity of the cooling machine 3, and the upstream side of the cooling machine 3 (from the cooling machine 3 On the water supply side), the water storage tank 4 and the circulation pump 21 are provided. On the downstream side of the cooler 3 (on the drainage side when viewed from the cooler 3), the circulation pump 21 and the cooling water are similarly provided. The cooling tower 22 is a cooling facility, and its end is connected to the water storage tank 4 so that the cooling water is circulated and supplied.

  The liquefied natural gas storage tank 6 provided in the liquefied natural gas storage / vaporization facility 8 has an outer wall so that the stored liquefied natural gas can be held at a low temperature of −162 ° C. or lower and in a liquid state under high pressure. A double wall structure is used, and a heat insulating material is filled between the double walls, and the heat insulating performance is enhanced by a substantially vacuum state. The lower part of the storage tank 6 is provided with a supply pipe 23 for filling the tank with liquefied natural gas conveyed from a tank truck or the like, and a delivery pipe for sending the liquefied natural gas to the downstream vaporizer 7. 24, a check valve 25 is provided in the middle of the supply pipe 23, and a shut-off valve 26 is provided in the middle of the delivery pipe 24.

  The vaporizer 7 vaporizes the low-temperature liquefied natural gas stored in the liquefied natural gas storage tank 6 by heat exchange with hot water as a heat medium, and the fuel of the gas burner 12 provided in the rotary kiln 2. And a container main body 27 that can temporarily store hot water, and the container main body 27 has a low-temperature liquefied natural gas delivered from the liquefied natural gas storage tank 6. A heat transfer tube 28 through which the gas passes is piped in a substantially spiral shape, and the chance of contact with the hot water supplied into the container main body 27 is increased as much as possible to increase the vaporization efficiency of the liquefied natural gas.

  On the other hand, the cooling water circulation circuit 5 downstream of the cooler 3 and upstream of at least the cooling tower 22 is connected to the container body 27 of the vaporizer 7, and the high-temperature object to be discharged from the rotary kiln 2 Hot water generated by the cooling process in the cooler 3 is supplied into the container main body 27 of the vaporizer 7 via the cooling water circulation circuit 5, and in the container main body 27, the hot water is used as a heat transfer tube. The vaporization process is performed by exchanging heat with the low-temperature liquefied natural gas passing through the interior of 28.

  Since liquefied natural gas is an extremely low temperature of −162 ° C. or lower, the temperature of hot water supplied as a heating medium does not necessarily have to be so high. For example, a sufficient temperature difference can be secured even at room temperature, and vaporization treatment can be performed. However, the higher the temperature of the hot water, the higher the efficiency of the vaporization process. For example, the combustion amount (natural gas consumption) of the gas burner 12 varies greatly depending on the amount of the object to be heated in the rotary kiln 2. Even in such a case, it becomes possible to cope with a margin.

  Reference numeral 29 in the figure denotes a buffer tank, and the natural gas generated by vaporization in the vaporizer 7 is temporarily stored in the buffer tank 29 and then gas is adjusted while adjusting the pressure by the pressure regulating valve 30. The gas is supplied to the gas burner 12 of the rotary kiln 2 through the supply pipe 31.

  When the heat treatment apparatus 1 having the above-described configuration is used to regenerate, for example, waste gypsum in the form of dihydrate gypsum as type II anhydrous gypsum, first, the gas burner provided in the rotary kiln 2 is used. While burning 12 and supplying hot air into the kiln main body 9, waste gypsum is thrown into the kiln main body 9 from the input chute 11 and is transferred to type II anhydrous gypsum while being exposed to hot air, for example, about 800 ° C. Heat treatment. During the initial combustion of the gas burner 12, it is difficult to generate sufficient natural gas because hot water is not supplied to the vaporizer 7, but it can be vaporized to some extent depending on the outside air temperature, and can be stored in the buffer tank 29. Therefore, it is possible to sufficiently cope with a very short time such as the initial combustion.

  The waste gypsum transferred to type II anhydrous gypsum is eventually discharged from the kiln main body 9, and sequentially fed to the lower water-cooled cooler 3 via the discharge chute 18 and sent out by the screw conveyor 19. Cooling is indirectly performed with cooling water supplied to the surrounding jacket portion 20, and then cooled to a temperature that is relatively easy to handle, for example, approximately 300 ° C., and then discharged.

  On the other hand, the cooling water supplied to the jacket portion 20 of the cooler 3 becomes, for example, about 40 to 70 ° C. as the high-temperature waste gypsum is cooled, and the cooling water circulation circuit 5 on the downstream side is changed. To the vaporizer 7 of the liquefied natural gas storage / vaporization facility 8. The hot water supplied to the vaporizer 7 is temporarily stored in the container body 27, and the low-temperature liquefied natural gas supplied from the liquefied natural gas storage tank 6 passes through the heat transfer pipe 28 disposed in the hot water. In the meantime, heat exchange is performed to vaporize the gas, and the natural gas is temporarily stored in the downstream buffer tank 29 and then supplied to the gas burner 12 of the nearby rotary kiln 2 through the gas supply pipe 31.

  Then, the hot water (cooling water) whose temperature is slightly lowered by heat exchange with the low-temperature liquefied natural gas in the vaporizer 7 is further cooled through the cooling tower 22 arranged downstream, and then the original water storage tank 4. And is circulated and supplied to the cooler 3 again as a refrigerant. At this time, the temperature of the warm water (cooling water) discharged from the vaporizer 7 is reduced by about 10 to 20 ° C. compared to the time of supply due to heat exchange with the liquefied natural gas. However, if the temperature is below about 40 ° C., for example, a cooling water cooling facility such as a high-cost cooling tower 22 or the like is unnecessary or a relatively small cooling capacity is sufficient, and the facility cost can be reduced.

  The present invention compares the materials to be treated, such as when reclaiming anhydrous gypsum from waste gypsum, when heating and purifying soil contaminated with oil, etc., when volatile separation of heavy metals contained in incineration ash by heating, etc. It can be widely used in a heat treatment apparatus used when heat treatment is required at a high temperature.

DESCRIPTION OF SYMBOLS 1 ... Heat processing apparatus 2 ... Rotary kiln (heating furnace)
DESCRIPTION OF SYMBOLS 3 ... Cooling machine 4 ... Water storage tank 5 ... Cooling water circulation circuit 6 ... Liquefied natural gas storage tank 7 ... Vaporizer 8 ... Liquefied natural gas storage and vaporization equipment 12 ... Gas burner 19 ... Screw conveyor (cooling machine)
20 ... Jacket part (cooler) 22 ... Cooling tower 27 ... Container body (vaporizer) 28 ... Heat transfer tube (vaporizer)
29 ... Buffer tank 31 ... Gas supply pipe

Claims (1)

  A heating furnace having a hot air supply burner for heat-treating an object to be processed at a high temperature, a water-cooled cooler for cooling the object to be processed discharged from the heating furnace, and cooling water for the cooler In a heat treatment apparatus provided with a cooling water circulation circuit that circulates and supplies to and from a water storage tank, the burner of the heating furnace is a gas burner that uses natural gas as fuel, and at least liquefied natural gas is placed in the vicinity of the heating furnace at low temperature and high pressure A liquefied natural gas storage tank having a liquefied natural gas storage tank and a vaporizer for vaporizing the liquefied natural gas stored in the liquefied natural gas storage tank. A cooling water circulation circuit on the downstream side of the cooler is connected to the vaporizer of the storage / vaporization facility, and the liquefied natural gas is vaporized with warm water generated when the high-temperature object is cooled with the cooler. The gas Heat treatment apparatus characterized by being configured to produce a natural gas, a fuel for over Na.

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