JP6979914B2 - Vaporizer - Google Patents

Description

The present invention relates to a vaporization device capable of stably vaporizing the raw material and maintaining the vaporized state even if the flow rate change and the mixing ratio of the gas-liquid mixture of the inflowing raw material and the carrier gas change.

In recent years, glass base materials for optical fibers have been increasing in size in order to improve productivity. The glass base material for an optical fiber is produced by a well-known method such as a VAD (Vapor Phase Axial Deposition) method, a MCVD (Modified Chemical Vapor Deposition) method, and an OVD (Outside Vapor Deposition) method.

In addition, Patent Document 1 describes a vaporizer for generating a raw material gas for a glass base material for an optical fiber, which controls the temperature inside the vaporizer by using a pair of heaters and a thermocouple. Has been done.

Japanese Unexamined Patent Publication No. 2002-124512

By the way, the raw material gas supplied to the burner via the supply pipe is vaporized by the vaporizer. A gas-liquid mixture of a raw material such as siloxane (for example, octamethylcyclotetrasiloxane; OMCTS) and a carrier gas is introduced into the vaporizer. A gas-liquid mixture of siloxane and carrier gas can be completely vaporized if the temperature is higher than the temperature (dew point) at which the vapor pressure of siloxane is equal to the partial pressure of the mixture in theory, but it is vaporized immediately. In order to do so, it is necessary to heat at a temperature sufficiently higher than that. On the other hand, if droplets adhere to a high temperature wall surface, there is a risk that gelation due to a polymerization reaction will be promoted. Therefore, the internal wall surface temperature of the vaporizer is limited to a certain range. For example, the raw material gas needs to be in the range of the boiling point of siloxane or higher and the boiling point of + 30 ° C. or lower.

Here, if the temperature of the inlet wall surface of the vaporizer is controlled, the wall surface on the downstream side through which the vaporized gas passes does not require latent heat of vaporization, and the temperature of the gas itself rises, so it is inevitable. It will be higher than the inlet temperature. As a result, the raw material gas is overheated and the risk of gelation increases. On the other hand, if the wall surface temperature on the downstream side of the vaporizer is controlled so as not to be excessively high, the temperature on the inlet side of the vaporizer will drop and it will not be possible to sufficiently vaporize.

In addition, when the flow rate of the gas-liquid mixture to be vaporized that flows into the vaporizer increases, if the temperature is controlled by the inlet wall temperature of the vaporizer, the raw material gas on the outlet side is overheated and there is a risk of gelation. If the temperature is controlled by the outlet wall surface temperature of the vaporizer, the temperature on the inlet side will drop and sufficient vaporization will not be possible.

Further, the temperature control becomes unstable depending on the mixing ratio of the raw material and the carrier gas in the gas-liquid mixture. This is because the raw material takes away the heat of vaporization when it vaporizes.

The present invention has been made in view of the above, and the vaporization of the raw material and the maintenance of the vaporized state are maintained even if the flow rate change and the mixing ratio of the gas-liquid mixture of the inflowing raw material and the carrier gas change. It is an object of the present invention to provide a vaporizer that can be stably performed.

In order to solve the above-mentioned problems and achieve the object, the vaporizer according to the present invention heats a pipe through which a gas-liquid mixture of a liquid material and a carrier gas flows, and vaporizes the liquid material within a predetermined temperature range. It is a vaporization device that outputs in the form of a vaporizer, and the region where the pipes are arranged is divided into a front stage region and a rear stage region. The inlet of the pipe based on the detection results of the heater, the front temperature sensor that measures the inlet temperature of the pipe in the front region, the rear temperature sensor that measures the outlet temperature of the pipe in the rear region, and the front temperature sensor. The detection result of the first-stage temperature control unit and the second-stage temperature sensor, which controls the temperature using the first-stage heater so that the temperature of the gas-liquid mixture is equal to or higher than the boiling point temperature of the gas-liquid mixture and equal to or lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature. With the post-stage temperature control unit that controls the temperature using the post-stage heater so that the temperature at the outlet of the pipe is equal to or higher than the boiling point temperature of the gas-liquid mixture and equal to or lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature. It is characterized by having.

Further, the vaporizer according to the present invention is characterized in that, in the above invention, the maximum heating output of the front stage heater is larger than the maximum heating output of the rear stage heater.

Further, in the above invention, the vaporizer according to the present invention provides an intermediate region between the front region and the rear region, and heats the pipe in the intermediate region with the intermediate heater and the temperature of the pipe in the intermediate region. The temperature of the pipe is equal to or higher than the boiling point temperature of the gas-liquid mixture and equal to or lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature based on the detection result of the intermediate temperature sensor and the intermediate temperature sensor. It is characterized by further providing an intermediate temperature control unit that controls the temperature using an intermediate heater.

Further, the vaporizer according to the present invention is characterized in that, in the above invention, the upper limit temperature is the upper limit temperature at which gelation of the vaporized liquid material does not occur.

Further, the vaporizer according to the present invention is characterized in that, in the above invention, the liquid material is siloxane and the margin temperature is 30 ° C.

According to the present invention, even if the flow rate change and the mixing ratio of the gas-liquid mixture of the inflowing raw material and the carrier gas change, the raw material can be vaporized and the vaporized state can be stably maintained.

FIG. 1 is a schematic diagram showing a configuration of a vaporizer according to an embodiment of the present invention. FIG. 2 is a diagram showing a temperature change of the raw material gas in the pipe when the flow rate of the inflowing gas-liquid mixture changes. FIG. 3 is a diagram showing a conventional temperature change of the raw material gas in the pipe when the flow rate of the inflowing gas-liquid mixture changes. FIG. 4 is a schematic diagram showing a configuration of a vaporizer which is a modification of the embodiment of the present invention. FIG. 5 is a diagram showing a temperature change of the raw material gas in the pipe 12 when the flow rate of the inflowing gas-liquid mixture is changed by the vaporizer shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing a configuration of a vaporizer 1 according to an embodiment of the present invention. As shown in FIG. 1, the vaporizer 1 has a vaporizer main body 10 and a temperature control unit 20.

The vaporizer main body 10 includes a corrosion-resistant (for example, stainless steel) pipe 12 through which a gas-liquid mixture to be vaporized flows, a front-stage heater 14 that heats the upstream (pre-stage) side of the pipe 12, and a downstream (previous stage) of the pipe 12. It has a rear heater 15 that heats the rear) side, a front temperature sensor 16 that measures the inlet temperature of the pipe 12, and a rear temperature sensor 17 that measures the outlet temperature of the pipe 12, and these are formed by casting with aluminum. The aluminum becomes, for example, an aluminum block 11 having a rectangular outer shape.

The inflowing gas-liquid mixture is a mixture of a raw material and a carrier gas, and the raw material is siloxane, specifically octamethylcyclotetrasiloxane. The carrier gas is an inert gas such as argon gas. The gas-liquid mixture flows in from the introduction port 12a of the pipe 12, and the vaporized mixed gas flows out from the outlet port 12b of the pipe 12.

The pipe 12 is made of stainless steel as described above, and is wound so as to draw a spiral in the aluminum block 11. The aluminum block 11 is divided into a front stage region E1 in which the front stage heater 14 is arranged and a rear stage region E2 in which the rear stage heater 15 is arranged. Is separated into. The first-stage region E1 is an evaporation region for vaporizing the raw material, and the second-stage region E2 is a temperature adjustment region for maintaining the temperature of the vaporized raw material gas.

The front stage heater 14 is arranged so as to be surrounded by the spiral of the pipe 12 in the front stage region E1 and heats the pipe 12. The rear heater 15 is arranged so as to be surrounded by the spiral of the pipe 12 in the rear region E2, and heats the pipe 12.

The pre-stage temperature sensor 16 is a thermocouple and is arranged in contact with the pipe at the inlet of the pipe 12 to the aluminum block 11 to measure the inlet temperature of the pipe 12. The post-stage temperature sensor 17 is a thermocouple, is arranged in contact with the pipe at the outlet from the aluminum block 11 of the pipe 12, and measures the outlet temperature of the pipe 12.

The temperature control unit 20 includes a front stage temperature control unit 21, a rear stage temperature control unit 22, a front stage heater power supply unit 23, and a rear stage heater power supply unit 24. The pre-stage temperature control unit 21 energizes and controls the pre-stage heater power supply unit 23 so that the temperature measured by the pre-stage temperature sensor 16 is within a predetermined temperature range, and controls the heating of the pre-stage heater 14. The predetermined temperature range is equal to or higher than the boiling point of siloxane and lower than the upper limit temperature obtained by adding the margin temperature (30 ° C.) to the boiling point. The rear-stage temperature control unit 22 controls the energization of the rear-stage heater power supply unit 24 so that the temperature measured by the rear-stage temperature sensor 17 is within a predetermined temperature range, and controls the heating of the rear-stage heater 15. That is, the temperature control for the front region E1 and the temperature control for the rear region E2 are performed independently.

Here, the maximum heating output of the front heater 14 is larger than the maximum heating output of the rear heater 15. This is because the pre-stage region E1 requires extra heat of vaporization when vaporizing the raw material.

FIG. 2 is a diagram showing a temperature change of the raw material gas in the pipe 12 when the flow rate of the inflowing gas-liquid mixture changes. In FIG. 2, the temperature change at the time of a small flow rate is shown by the curve L1, and the temperature change at the time of a large flow rate is shown by the curve L2. As shown in FIG. 2, even if the flow rate of the gas-liquid mixture is different, the inlet temperature at which the front temperature sensor 16 is arranged maintains a boiling point T1 or higher even though the heat of vaporization is taken away, and the rear temperature sensor 17 The outlet temperature at which is arranged does not exceed the upper limit temperature T2, which is the boiling point plus the margin temperature of 30 ° C. As a result, the vaporized mixed gas can suppress gelation in the vaporizer main body 10.

Further, when the flow rate is large, the maximum heating output in the front region E1 is larger than that in the rear heater 15, so that the raw material can be sufficiently vaporized, and this large heating output affects the rear region E2. Therefore, the temperature can be easily controlled so that the vaporized mixed gas in the subsequent region E2 does not exceed the upper limit temperature.

Therefore, in the present embodiment, even if the flow rate change and the mixing ratio of the gas-liquid mixture of the inflowing raw material and the carrier gas change, the raw material can be vaporized and the vaporized state can be stably maintained.

As shown in FIG. 3, when the temperature of the mixed gas in the pipe is controlled by one heater and one temperature sensor, when the inflowing gas-liquid mixture has a small flow rate, the mixed gas is kept in a predetermined temperature range. Although it can be accommodated inside (see curve L101), when the inflowing gas-liquid mixture has a large flow rate and the temperature control point is the inlet, the amount of heat for vaporization becomes large and the heat is generated. It is also transmitted to the piping on the rear stage side, and the outlet temperature exceeds the upper limit temperature, which promotes the gelation of the vaporized raw material gas (see curve L103).

On the other hand, when the inflowing gas-liquid mixture has a large flow rate and the temperature control point is the outlet, the heating amount for vaporization cannot be increased and sufficient vaporization cannot be performed (curve). See L102).

<Modification example>
FIG. 4 is a schematic view showing the configuration of the vaporizer 1'which is a modification of the embodiment of the present invention. As shown in FIG. 4, the vaporizer main body 10'of the vaporizer 1'provides an intermediate region E21 further independent between the front region E1 and the rear region E22 corresponding to the rear region E2. The flow in the longitudinal direction of the front region E1, the intermediate region E21, and the rear region E22 can be arbitrarily set. For example, the front region E1 may be left as it is, and the rear region E2 may be divided into an intermediate region E21 and a rear region E22.

Heat insulating surfaces 13a and 13b corresponding to the heat insulating surface 13 are formed between the front region E1 and the intermediate region E21, and between the intermediate region E21 and the rear region E22, respectively. Further, in the intermediate region E21, an independent intermediate heater 18 is provided and an intermediate temperature sensor 19 is provided. The intermediate temperature control unit (not shown) controls the heating amount of the intermediate heater 18 so that the temperature measured by the intermediate temperature sensor 19 is within a predetermined temperature range. The intermediate temperature sensor 19 comes into contact with the pipe 12, but the arrangement position on the pipe 12 is arbitrary. The maximum heating output is increased in the order of the rear heater 15, the intermediate heater 18, and the front heater 14.

FIG. 5 is a diagram showing a temperature change of the raw material gas in the pipe 12 when the flow rate of the inflowing gas-liquid mixture is changed by the vaporizer 1'shown in FIG. In FIG. 5, the temperature change at the time of a small flow rate is shown by the curve L11, and the temperature change at the time of a large flow rate is shown by the curve L12. As shown in FIG. 5, even if the flow rate of the gas-liquid mixture is different, the inlet temperature at which the front temperature sensor 16 is arranged maintains a boiling point T1 or higher even though the heat of vaporization is taken away, and the rear temperature sensor 17 The outlet temperature at which is arranged does not exceed the upper limit temperature T2, which is the boiling point plus the margin temperature of 30 ° C. As a result, the vaporized mixed gas can suppress gelation in the vaporizer main body 10. Further, the temperature between the heat insulating surfaces 13a and 13b where the intermediate temperature sensor 19 is arranged is also controlled so as to be maintained within a predetermined temperature range.

Further, at the time of a large flow rate, in the front stage region E1, the maximum heating output is larger than that of the intermediate heater 18 and the rear stage heater 15, so that the raw material can be sufficiently vaporized, and this large heating output is in the intermediate region. Since it does not affect the E21 and the latter region E22, the temperature of the intermediate region E21 and the latter region E22 can be easily controlled so that the vaporized mixed gas does not exceed the upper limit temperature.

Therefore, also in this modification, as in the embodiment, the vaporization of the raw material and the maintenance of the vaporized state are stable even if the flow rate change and the mixing ratio of the gas-liquid mixture of the inflowing raw material and the carrier gas change. Can be done. In particular, in this modification, since the multi-step temperature control including the intermediate region E21 is performed, fine-grained temperature control becomes possible.

In the above-described embodiments and modifications, siloxane is taken as an example of the raw material to be vaporized, but the present invention is not limited to this, and can be applied to _{, for example, silicon tetrachloride (SiCl 4).}

Although the embodiment to which the invention made by the present inventors has been applied has been described above, the present invention is not limited by the description and the drawings which form a part of the disclosure of the present invention according to the present embodiment. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

1,1 ′ Vaporizer 10, 10 ′ Vaporizer body 11 Aluminum block 12 Piping 12a Introductory port 12b Outlet port 13, 13a, 13b Insulation surface 14 Front heater 15 Rear heater 16 Front temperature sensor 17 Rear temperature sensor 18 Intermediate heater 19 Intermediate Temperature sensor 20 Temperature control unit 21 Front stage temperature control unit 22 Rear stage temperature control unit 23 Front stage heater power supply unit 24 Rear stage heater power supply unit E1 Front stage region E2 Rear stage region E21 Intermediate region E22 Rear stage region L1, L11, L12, L2 Curve T1 Boiling point T2 upper limit temperature

Claims (5)

A vaporizer that heats a pipe through which a gas-liquid mixture of a liquid material and a carrier gas flows to vaporize the liquid material within a predetermined temperature range and output the liquid material.
The area where the pipes are arranged is divided into a front-stage area and a rear-stage area.
A pre-stage heater that heats the piping in the pre-stage region,
A post-stage heater that heats the piping in the post-stage region,
A pre-stage temperature sensor that measures the inlet temperature of the pipe in the pre-stage region,
A post-stage temperature sensor that measures the outlet temperature of the piping in the post-stage region,
Based on the detection result of the pre-stage temperature sensor, the temperature is set by using the pre-stage heater so that the temperature at the inlet of the pipe is equal to or higher than the boiling point temperature of the gas-liquid mixture and equal to or lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature. The pre-stage temperature control unit to control and
Based on the detection result of the latter stage temperature sensor, the temperature using the latter stage heater is set so that the temperature at the outlet of the pipe is equal to or higher than the boiling point temperature of the gas-liquid mixture and lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature. The post-stage temperature control unit to control and
A vaporizer characterized by being equipped with. The vaporization device according to claim 1, wherein the maximum heating output of the front-stage heater is larger than the maximum heating output of the rear-stage heater. An intermediate region is provided between the front region and the rear region.
An intermediate heater that heats the piping in the intermediate region and
An intermediate temperature sensor that measures the temperature of piping in the intermediate region,
Based on the detection result of the intermediate temperature sensor, the temperature of the pipe is controlled by using the intermediate heater so that the temperature of the pipe is equal to or higher than the boiling point temperature of the gas-liquid mixture and equal to or lower than the upper limit temperature obtained by adding the margin temperature to the boiling point temperature. Intermediate temperature control unit and
The vaporizer according to claim 1 or 2, further comprising. The vaporization apparatus according to any one of claims 1 to 3, wherein the upper limit temperature is an upper limit temperature at which gelation of the vaporized liquid material does not occur. The liquid material is siloxane,
The vaporizer according to any one of claims 1 to 4, wherein the margin temperature is 30 ° C.

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