Gas flow regulator for gases with condensable components

A gas flow regulator for gases with condensable components, which delivers ases at constant pressure with constant average composition comprising a gas flow control mechanism, preferably including a spring-loaded membrane bounding a receiving chamber, which is subjected to the pressure of the gases flowing in and which an inlet valve control; and a cooling section connected and vertically oriented to the gas flow control mechanism by which the proportions of the condensable components are held at a partial pressure given by the cooling temperature, and a means for maintaining the gas flow control mechanism at a temperature above the condensation point. A restrictor, preferably an adjustable outlet valve, is connected after the cooling section to help maintain the membrane under pressure by the flowing gas, from which all condensate formed arrives in the region below the regulator directly by action of the force of gravity.

FIELD OF THE INVENTION 
Our present invention relates to a gas flow regulator for controlling the 
flow of a gas under pressure and, more particularly, to a gas flow 
regulator for controlling the flow of a gas containing a condensable 
component. 
BACKGROUND OF THE INVENTION 
A prior art gas flow regulator can comprise a gas flow control mechanism, 
including a spring-loaded membrane bounding a gas-receiving chamber, which 
is subjected to the pressure of the input gas, and a flow-control valve 
connected to the membrane and a restrictor or constriction at the outlet 
of the gas flow regulator. The constriction and the force of the spring 
can be controllable. 
For the regulation of the flow rate of liquids and gases a membrane flow 
regulator of this type is known, in which the outlet flow of an adjustable 
valve is controlled by an adjustable spring-loaded flexible membrane so 
that with increased fluid input the output cross section of the valve is 
reduced. This membrane bounds a space in which the fluid arrives through 
the adjustable valve and which is connected with a restrictor, through 
which the fluid flows. 
One such regulator, for example, is taught in German utility model DE-GM 
No. 16 56 212, in which a reducing valve is provided as a restrictor, 
leading to a flow meter connected to it after the principal flow element 
and to the outflow side of the space over the membrane. With this 
additional mechanism the flow adjustment precision is improved. 
A similar regulator is described in German patent document DE-OS No. 21 55 
323, which to be sure has no flow meter. Another membrane flow regulator 
of the above type is described in German patent document DE-OS No. 23 34 
348 in which a pressure surge is attenuated by a compensating member, 
particularly in the form of an attenuating piston, subjected to the 
inlet-side pressure and passing through the membrane. 
Finally, in French patent document No. 23 49 084, a membrane flow regulator 
is taught, in which the spring acting on the membrane is formed as a kind 
of leaf spring and a plunger or push rod shaped connecting body engaged by 
the membrane acts on the regulating valve. On the outlet side a fine 
orifice is provided as a restrictor, after which a by-pass to the space 
adjacent the membrane branches off. This regulator is suitable for 
regulation of very slight flow rates in low pressure flows. 
All these known regulators employed as gas flow meters presuppose gases, 
which do not change their composition during the regulating process, for 
example, do not condense out or have components which condense out since 
on the other hand the functioning of the regulating process would be 
disturbed by the condensate formed by the condensation process. 
Furthermore, because of the condensation irregular variation of 
undetermined components in the mixture could occur, which would be a 
particular problem for gas flows with nonuniform gas compositions. 
OBJECTS OF THE INVENTION 
The aim of our invention is, therefore, the development of a gas flow 
regulator of the above-described kind, from which instead of varying 
portions of the condensable and condensate soluble components of the 
inflowing gases a constant gas flow with uniform pressure is delivered and 
all condensate formed preferably directly with the gas, from which it 
condenses, reaches a subsequent region so that the proportions of it 
correspond substantially to those of the original gas composition. 
It is an object of our invention to provide an improved gas flow regulator 
for gases with condensable components. 
It is also an object of our invention to provide an improved has regulator 
for gases with condensable components which delivers an output flow in 
which the proportions of the components, condensable and noncondensable, 
are substantially the same as those of the original mixture. 
It is a further object of our invention to provide an improved gas 
regulator for gases with condensable components, which provides a constant 
gas flow with a uniform pressure with substantially no variations in 
average gas composition. 
It is also an object of the invention to obviate disadvantages of the prior 
art. 
SUMMARY OF THE INVENTION 
These objects and others, which will become more apparent hereinafter, are 
attained in accordance with our invention in a gas flow regulator for 
gases with condensable components comprising a gas flow control mechanism, 
preferably including a spring-loaded membrane bounding a gas-receiving 
chamber which is subjected to the pressure of the input gas, a controlling 
inlet valve connected to the membrane, and a restrictor or constriction at 
the outlet of the gas flow regulator. 
According to our invention for the condensation of the condensable 
components a cooled cooling section is provided substantially vertically 
between the gas flow control mechanism, or preferably the gas-receiving 
chamber, and the restrictor, from which all condensate formed directly 
reaches the region underneath the mechanism by the action of the force of 
gravity. 
In a preferred embodiment of our invention the restrictor is an adjustable 
outlet valve. 
For avoidance of undesired condensation the structural components upstream 
of the cooling section must be held at a temperature over the condensation 
point or dewpoint for the gas mixture. Therefore a means for maintaining 
the temperature of the gas flow control mechanism above the condensation 
point is provided. This means can include a housing or layer of thermal 
insulation. 
With this arrangement constant pressure and composition gases are 
delivered, wherein the condensate formed with soluble components 
practically without delay is transported by gravity and entrainment in a 
fluid mixture with the gas, and reaches the directly connected subsequent 
region, for example, reaches an analyzer. 
In a preferred embodiment of our invention the cooling section is provided 
with a cooling jacket through which a coolant may be circulated. 
A gas flow regulator of the present type is needed particularly in 
connection with a polarographic analyzer for determination of SO.sub.2 in 
gases, e.g. furnace, stacks or flue gases which has an internally driven 
electrolytic circulation according to the gas lift or MAMMUT pump 
principle. Polarographic analyzers react sensitively to all changes in the 
surroundings. A particularly important requirement, which maintains the 
internal electrolyte circulation constant, is that the cell must be 
provided with constant input gas flow rates at constant pressure. 
In a preferred embodiment of our invention coupled to a polaragraphic 
analyzer, the cooling of the cooling section is provided by the 
polarographic analyzer. Preferably the electrolyte used in the polarograph 
can be circulated through a cooling jacket for the cooling section. 
Gas mixtures, particularly smoke from chimneys, whose analysis and 
observation is a particular application for our invention, contain various 
proportions of water vapor, whose condensation leads to variations of the 
noncondensable residual gas flow, which is responsible for the electrolyte 
circulation. 
We cannot, to meet this problem, provide a cooling section before the gas 
flow regulator, as thus uncontrolable amounts of the sulfur dioxide in the 
composition would be eliminated on account of the solubility of sulfur 
dioxide in water condensed in such a cooling section. 
Also the regulator apparatus cannot be connected to the outlet of the 
analyzer components, since the gas pressure behind the analyzer, which 
operates near atmospheric pressure is not sufficient for the functioning 
of the regulator. 
Although the gas flow regulator was especially developed for the operation 
of a polarographic SO.sub.2 analyzer with electrolytic circulation (as 
described in German patent application P 33 08 888.8-1) and the present 
description mostly refers to this purpose, we wish to make clear that the 
arrangement according to our invention is applicable for every system with 
condensable components, e.g. for the regulation of gases containing vapors 
of condensable organic solvents. 
In a preferred embodiment of our invention, particularly useful for 
polarographic analysis, the cooling section is a cooling pipe with an 
inner diameter of from substantially 5 to 15 mm and a length from 5 to 15 
cm.

SPECIFIC DESCRIPTION 
The gas flow regulator shown in FIG. 1 comprises a housing 1 having a 
gas-receiving chamber 2, which is bounded by a membrane 3, against which a 
spring 4 acts. 
This membrane 3 adjusts to the pressure of the gases flowing in the gas 
inlet 5 and controls the size of the passage opening 14 for the gas flow 
by the valve mechanism comprising passage 6, push rod 7, ball 8 and spring 
9. 
A cooling section 10 (electrolyte-traversed liquid jacket condenser) is 
attached directly to the preferably disk-shaped gas-receiving chamber 2, 
and is so dimensioned that the partial pressure of the condensable 
components is maintained at the vapor pressure corresponding to the 
temperature of the cooling section. 
A restrictor in the form of a regulating or adjustable outlet valve 11 
necessary for keeping the membrane 3 under pressure is connected to the 
cooling section 10. Instead of the regulating or adjustable outlet valve 
11, a capillary tube or an arbitrary constriction can be provided. The 
cooling section or condenser section 10 has a cooling jacket 12, which 
particularly is included in the electrolytic circulation path of an 
SO.sub.2 polarographic analyzer. 
The housing 1, the gas-receiving chamber 2, the membrane 3 with the spring 
4, the gas inlet 5, the passage 6, push rod 7, ball 8 and spring 9 
together may be considered as a gas flow control mechanism 16 of the gas 
flow regulator. The gas flow control mechanism 16 requires a means 15 
(e.g. a layer of insulation or heating bandage) by which its temperature 
is maintained above the temperature at which condensation occurs in the 
input gases. 
The cooling section 10 may advantageously be a perpendicular cooling pipe 
10 with an inner diameter d, of from substantially 5 to 15 mm and a length 
l from 5 to 15 cm. 
In FIG. 2 the gas flow regulator is shown coupled to a polarographic 
analyzer. In this example the coolant used by the cooling jacket 12 is 
provided by the electrolyte found in the electrolyte reservoir E of the 
polarograph P. This electrolyte reservoir E has an outlet 24 connected to 
the inlet 27 of the jacket 12 of the cooling section 10 and an inlet 22 
connected to the outlet 25 of the jacket 12. The polarograph P is of a 
standard design and the electrolyte can be circulated by gas entrainment 
with the admitted has using gas-lift or MAMMUT pum principles.