Gas and liquid contact apparatus – Fluid distribution – Valved
Reexamination Certificate
2000-09-13
2004-06-22
Bushey, Scott (Department: 1724)
Gas and liquid contact apparatus
Fluid distribution
Valved
C261S044500, C261S066000, C261S142000, C261SDIG006, C118S726000
Reexamination Certificate
active
06752387
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a method and apparatus for mixing and gasifying a reactant gas-liquid and more particularly a method and device that can provide stable control of a delivery of a reactant gas over a range of flow rates to, for example, a semiconductor production line.
2. Description of Relevant Art
Among the conventional liquid material gasifying apparatus, there is a device which is designed to gasify a liquid material within a three-way control valve equipped with a flow control function, as described, for example, in U.S. Pat. No. 5,419,924.
FIG. 9
is a view showing a principal part of this liquid material gasifying apparatus. A control valve
70
is furnished with a flow control function, with a valve body
71
formed with a recess
72
. The part
73
is a driving part which is provided to block a portion of the recess
72
, and is furnished with a plunger
74
which rises and descends in the recess
72
. A valve seat
75
is formed on the upper part of a projection
76
projecting upward from the center of the bottom face of the valve body
71
. A flexible diaphragm
77
divides the inside of the recess
72
into an upper space
78
including the plunger
74
and a lower space
79
including the valve seat
75
, and the diaphragm
77
is constituted to come into scaling contact with the upper surface of the valve seat
75
by the descending of the plunger
74
to seal the valve seat
75
.
A liquid material introduction channel or route
80
is formed to penetrate vertically from the center of the bottom face of the valve body
71
to a position where the diaphragm
77
on the upper face of the valve seat
75
can come into tight contact. A carrier gas induction route
81
, and a mixed gas discharge route
92
, which are formed to communicate in a space formed around the valve seat
75
at the time when the diaphragm
77
is brought into tight contact with the upper face of the valve seat
75
.
In the control valve
70
of the above constitution, a liquid material
83
from a liquid material tank (not illustrated) is led upward in the liquid material introduction route
80
and introduced into the control valve
70
with the flow rate controlled, and a carrier gas
84
at a high temperature (e.g., 70°C.) from a carrier gas source (not illustrated) is introduced into the control valve
70
through the carrier gas introducing route
81
. The control valve
70
allows the liquid material to be in contact with the high temperature carrier gas
84
to gasify the liquid material
83
into reactant gas, so that this reactant gas is mixed with the carrier gas
84
, and this mixed gas
85
is led outside the control valve
70
through the mixed gas discharge route
82
.
However, in the above liquid material gasify apparatus, the efficiency of actual use of the carrier gas
84
can be poor, and there is a possibility that the liquid material
83
cannot always be gasified into a stabilized state with good efficiency. This situation can be explained while referring to FIG.
10
and FIG.
11
.
Firstly,
FIG. 10
shows the flow of the liquid material
83
and the carrier gas
84
in an open state of the valve seat
75
, in which the carrier gas
84
, introduced into the lower space
79
through the carrier gas induction route
81
flows between the upper surface of the valve seat
75
and the diaphragm
77
, as shown by arrow marks
84
a
to come into contact across the surface of the liquid material
83
which has been guided upward in the liquid material induction route
80
. During this operation, a major part of the carrier gas
84
flows in such a manner to be diverted along the perimeter of the valve seat
75
and the body projection
76
underneath, as shown in arrow marks
84
b
. As a result of such diversion of flow, the introduced high temperature carrier gas
84
does not necessarily make a major contribution to an acceleration of the gasification of the liquid material
83
, and accordingly, the partial pressure above the liquid surface may come to a nearly saturated condition, so that condensation is apt to be formed.
In the above liquid material gasifying apparatus, there is a possible drawback that, when the amount of induction of the liquid material
83
into the control valve
70
increases, gasification of such material will not be stable. That is, when a change in the gas flow from the control valve
70
was observed at time periods of having increased stepwise amounts of induction of the liquid material
83
into the control valve
70
while retaining the amount of induction of the carrier gas
84
constant, the results as shown in FIG.,
11
were obtained.
In
FIG. 11
, the mark a shows an amount of induction of the carrier gas
84
, which is in this example is 2000 cc/min. And, the mark b shows the amount of induction of the liquid material (e.g., ethanol)
83
, which is in this example changed stepwise from 0.2 cc/min. to 1.0 cc/min. Further, the mark c represents a change in flow volume of the gas led out from the control valve
70
. From this
FIG. 11
, it can be seen that the gas flow volume changes over a relatively stabilized manner when the induction amount of ethanol
83
is relatively small, but when the induction amount increases, overshooting or wide fluctuations may occur.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for gasifying a liquid material and an apparatus thereof so that gasification of a liquid material such as a reactant can be accomplished efficiently and in a stabilized manner at all times.
In order to attain the above object, a method for gasifying a liquid material comprises mixing or entraining a liquid material and a carrier gas while providing flow control in a gas-liquid mixing unit of a control valve provided with a liquid flow control function, and discharging the gas-liquid mixture from a nozzle formed in the vicinity of the flow control unit to fully gasify the liquid material at a reduced pressure level.
An apparatus for practicing the above liquid material gasifying method includes a liquid material supply line equipped with a liquid tank and a flow meter for measuring the flow of the liquid material from the liquid tank and a carrier gas supply line equipped with a carrier gas supply source and a flow control apparatus for controlling the flow of the carrier gas. Each supply line is connected with the control valve independently from each other. A gas-liquid mixing unit and a nozzle unit are formed in close relationship to each other in the control valve, so that the liquid material introduced into the control valve by the above liquid material supply line is released into the carrier gas by an annular gap between a diaphragm and a valve seat. Thus, the liquid material is at a higher pressure than the carrier gas and is released radially inward in controlled discrete amounts to mix with the carrier gas within a mixing channel. Heat can be supplied to both the nozzle unit and the valve seat to raise the temperature of the liquid material. The carrier gas is introduced into the mixing channel of the control valve by the carrier gas supply line while controlling the flow volume, the gas-liquid mixture formed at this time is discharged from the above nozzle to gasify the liquid material at a reduced pressure level, and the gas formed by gasification, along with the carrier gas, is taken out from the gas discharge route on the downstream side of the nozzle.
Flow control of the liquid material in the above control valve may be made based on the output of a flow meter for the liquid or the output of the flow meter for the gas which is provided on the gas supply line.
In this invention, the liquid material and the carrier gas are mixed while controlling the flow in the gas and liquid mixing unit in the control valve equipped with a liquid flow control function, and the gas-liquid mixture can be subjected to reduced pressure instantly at the nozzle, so that the liquid material can be gasified in good efficiency and in a stabil
Miyamoto Hideaki
Nishizato Hiroshi
Bushey Scott
Stec Inc.
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