RAPID ON-DEMAND HUMIDIFICATIQN SYSTEM AND HUMIDIFICATIQN PROCESSES

PRIORITY CLAIM This application claims priority to U.S. Provisional Application Serial No.

61/012,888, filed December 11, 2007, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to humidification processes and systems. More specifically, the invention relates to processes and systems for controllably humidifying and heating a stream of gas.

Discussion of the Background Information

Humidification systems produce a stream of humidified gas by adding water vapor to an initial stream of gas. One manner of achieving such a humidified gas is by utilizing a bubbler system. In a bubbler system, the initial stream of dry gas is fed through a quantity of heated water and/or water vapor. The gas stream absorbs some of the water vapor thus producing a humidified gas stream. However, such bubbler systems are relatively slow to humidify the initial stream of gas. Further, such bubbler systems do not adapt well to a change in target humidity.

Another manner of achieving such a humidified gas is by utilizing a steam injection system. In a steam injection system, a stream of heated water vapor is combined with the initial stream of dry gas thus producing a humidified stream. Such steam injection systems humidify the initial stream of gas at a higher rate than bubbler systems. However, steam injection systems produce combined streams that are typically difficult to control. Further, the ranges of the target temperatures and humidities are limited. Thus, the need exists for improved humidification systems and processes in which a stream of gas may be controllably humidified to a target humidity. The need also exists

for humidification systems and processes that are capable of quickly and controllably forming a humidified stream at a desired temperature.

SUMMARY OF THE INVENTION The invention relates to processes and systems for producing a temperature- controlled humidified gas stream.

One embodiment of the inventive process comprises the steps of humidifying a first component stream; heating a second component stream; providing a third component stream; and merging at least the first, second and third component streams to produce the temperature-controlled humidified gas stream.

In one aspect, the process further comprises the steps of controllably separating an initial gas stream into at least the first component stream, thereby leaving a remainder stream; and controllably separating the remainder stream into at least the second component stream and the third component stream, the third stream being neither humidified nor heated.

In another aspect, the merging step comprises merging the first component stream with the second component stream to produce an intermediate stream and merging the intermediate stream with the third component stream to produce the temperature- controlled humidified gas stream. In another aspect, the process further comprises the steps of calculating a target amount of water vapor necessary to achieve a target humidity in the temperature- controlled humidified stream; and adjusting the flow rate of the first component stream, according to the calculation, such that the target amount of water vapor for the temperature-controlled humidified stream is introduced into the first component stream. In another aspect, the process further comprises adjusting the flow rate of at least one of the second and third component streams, based on temperature information of the temperature-controlled humidified gas stream, such that the temperature of the temperature-controlled humidified gas stream approaches a target temperature.

In another aspect, the humidifying occurs in a humidifying bottle containing water and humidification tubing made of water-permeable material, wherein the humidification tubing is disposed in the water and conveys the first component stream therethrough.

One embodiment of the inventive system comprises one or more separation devices for separating an initial gas stream into a first component stream, a second component stream and a third component stream; a humidification device for humidifying the first component stream of gas; a heating device for heating the second component stream of gas; and a mixing zone in fluid communication with the humidification device, the heating device and the one or more separation devices for merging at least the first, second and third component streams, in any order, to produce the temperature-controlled humidified gas stream.

In one aspect, the mixing zone merges the first component stream with the second component stream to produce an intermediate stream; and merges the intermediate stream with the third component stream to produce the temperature-controlled humidified gas stream.

In another aspect, the system further comprises a humidity control system for calculating a target amount of water vapor necessary to achieve a target humidity in the temperature-controlled humidified stream.

In another aspect, the humidity control system is capable of adjusting the flow rate of the first component stream, according to the calculation, such that the target amount of water vapor for the temperature-controlled humidified stream is introduced into the first component stream. In another aspect, the system further comprises a temperature control system for adjusting the flow rate of at least one of the second and third component streams based on temperature information of the temperature-controlled humidified gas stream such that the temperature of the temperature-controlled humidified gas stream approaches a target temperature. In another aspect, the humidification device is a humidifying bottle containing water and humidification tubing made of water-permeable material, wherein the humidification tubing is disposed in the water and conveys the first component stream therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments, in conjunction with the accompanying drawings, wherein like reference numerals have been used to designate like elements, and wherein:

Figure 1 is a schematic showing a preferred embodiment of the invention;

Figure 2 is a graph plotting humidifying bottle temperature, target stream temperature, and temperature-controlled humidified gas stream temperature versus time for a temperature increase from 55 ⁰ C to 75 ⁰ C;

Figure 3 is a graph plotting target stream humidity and temperature-controlled humidified gas stream humidity versus time for a humidity increase from 25% to 75%;

Figure 4 is a graph plotting humidifying bottle temperature, target stream temperature, and temperature-controlled humidified gas stream temperature versus time for a temperature increase from 40°C to 70 ⁰ C;

Figure 5 is a graph plotting target stream humidity and temperature-controlled humidified gas stream humidity versus time for a humidity increase from 50% to 70%;

Figure 6 is a graph plotting humidifying bottle temperature, target stream temperature, and temperature-controlled humidified gas stream temperature versus time where target temperature is maintained at 55 ⁰ C; and

Figure 7 is a graph plotting target stream humidity and temperature-controlled humidified gas stream humidity versus time for a humidity decrease from 100% to 25%.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally relates to processes and systems for producing temperature-controlled humidified gas streams. The processes and systems desirably provide the ability to carefully control the temperature and humidity of the temperature- controlled humidified gas stream. Preferably, the processes and system are capable of rapidly changing the humidity and temperature of an initial gas stream to a target temperature and a target humidity. In one embodiment, the invention is to a process for producing a temperature- controlled humidified gas stream, the process comprising the steps of humidifying a first

component stream; heating a second component stream; providing a third component stream; and merging at least the first, second and third component streams to produce the temperature-controlled humidified gas stream. According to this aspect of the invention, the temperature and humidity of the temperature-controlled humidified gas stream can be carefully controlled by adjusting the flows of the first, second and third component streams.

In another embodiment, the invention is to a system for producing a temperature- controlled humidified gas stream, the system comprising one or more separation devices for separating an initial gas stream into a first component stream, a second component stream and a third component stream; a humidification device for humidifying the first component stream of gas; a heating device for heating the second component stream of gas; and a mixing zone in fluid communication with the humidification device, the heating device and the one or more separation devices for merging at least the first, second and third component streams, in any order, to produce the temperature-controlled humidified gas stream.

FIG. 1 provides a non-limiting example of a system according to one embodiment of the present invention. As shown, an initial gas stream 110 is separated into a first component stream 112 thereby leaving a remainder stream 114. The remainder stream 114 is then separated into a second component stream 116 and a third component stream 118. The initial stream 110 preferably is at ambient temperature and relative humidity. The third component stream 118 preferably remains at ambient temperature and humidity. In other words, in a preferred embodiment, the third component stream 118 is neither humidified nor heated. Optionally, the initial gas stream 110 is separated into the first, second and third component streams 112,116, 118 in any order. As one alternative, the initial stream 110 is a stream, at any temperature, that requires heating and humidifying. As another alternative, the initial stream 110 is a stream, at any humidity, that requires heating and humidifying. In still another alternative, the initial stream 110 is a stream, at any temperature and/or at any humidity, that requires heating and/or humidification. In one exemplary embodiment, the remainder stream 114 comprises all of the remaining gas that is not in the first component stream 112.

In some of the preferred embodiments, the flow rates of the second and third component streams 116, 118 are inversely related to one another, e.g., a larger flow rate in the second component stream 116 results in a smaller flow rate in the third component stream 118 and vice versa. Accordingly, an exemplary embodiment of the inventive system comprises a separation sub-system 120, as shown in Figure 1, for receiving the initial stream 110 and controllably separating the initial stream 110 into the first, second and third component streams 112, 116, 118. In the embodiment of FIG . 1, the separation sub-system 120 comprises one or more separation devices to perform the separation steps. Specifically, as shown, the separation devices include mass flow controllers 121a, 121b, 121c.

Optionally, the separation sub-system 120 comprises at least one valve (not shown). As another option, the separation sub-system 120 comprises a combination of valves and mass flow controllers 121.

In an exemplary embodiment, one mass flow controller 121a separates the first component stream 112 from the initial stream 110, another mass flow controller 121b separates the second component stream 116 from the remainder steam 114 and still another mass flow controller 121c receives and directs the remaining third component stream 118. Of course, the initial stream 110 may be separated, in any order, into the first, second and third component streams 112, 116, 118, and the order of the separation herein with respect to FIG 1. is but an exemplary embodiment. As another option, a flow controller is utilized in conjunction with valves to further control and adjust the flow rate of the respective stream. Alternatively, the separation sub-system 120 separates the initial stream 110 into more than three component streams, e.g., more than four component streams, more than five component streams, or more than six component streams.

One preferred embodiment of the process comprises the step of humidifying the first component stream 112. In doing so, water vapor is added to the first component stream 112 by a humidification device 122. As other options, the humidification device 122 is any humidification device known in the art. In an exemplary embodiment, as shown, the humidification device 122 is a humidifying bottle 124. The humidifying bottle 124 contains water and humidification tubing 126 made of water-permeable

material. The humidification tubing 126 conveys the first component stream 112 through the water in the humidifying bottle 124. In doing so, some of the water permeates through the humidification tubing 126 as water vapor and into the first component stream 112, thereby humidifying the first component stream 112. One such water-permeable material is Nafion™ manufactured by E. I. DuPont de Nemours and Company. As an example, a length of at least one half meter of humidification tubing 126 may be used for each 3 standard liters per minute (s.l.m.) of flow, e.g., at least one meter of humidification tubing 126 may be used for each 3 s.l.m of flow., or at least two meters of humidification tubing 126 mat be used for each 3 s.l.m of flow. In one example, a thermocouple (not shown) is disposed inside the humidification device 122, e.g., humidifying bottle 124, to monitor and control the temperature of the humidification device 122. In one preferred embodiment, the humidifying bottle 124 is maintained at a temperature higher than the temperature of the ambient initial stream 110. In an exemplary embodiment, the temperature of the humidifying bottle 124 can be at least 5°C higher than a maximum target temperature for the temperature-controlled humidified stream 100, e.g., at least 10°C higher, at least 15°C higher, or at least 2O ⁰ C higher. In one aspect, the humidifying bottle 124 and its components are sized to handle at least the maximum flow, e.g., at least 110% of maximum flow, at least 125% of maximum flow, or at least 150% of maximum flow. Alternatively, the humidification device 122 is a steam injection system or a bubbler system. In such a case, the thermocouple may be attached to the respective humidification device 122.

In a preferred embodiment, the process further comprises the step of heating the second component stream 116. The heating is performed by a heating device 128. As other options, the heating device 128 can be any suitable heater that can increase the temperature of some or all of an initial stream of gas. In one exemplary embodiment, a thermocouple (not shown) is disposed adjacent the heater to monitor and control the temperature thereof. In one aspect, the heating device 128 is configured, e.g., sized, to raise the temperature of the ambient gas to up to 300 ⁰ C at maximum flow conditions, e.g., up to 250 ⁰ C at maximum flow conditions, 200 ⁰ C at maximum flow conditions, or 150°C at maximum flow conditions.

In a preferred embodiment, the process further comprises the step of providing the third component stream 118, which preferably is done through the separation sub-system 120. In another preferred embodiment, mass controller 121c controls the flow of the third component stream 118. The third component stream 118 preferably remains at ambient temperature and pressure; it is preferably neither heated nor humidified. Optionally, the third component stream 118 is cooled. As another option, the third component stream 118 is heated, but to a different temperature from the second component stream 116.

In a preferred embodiment, the process further comprises the step of merging the humidified first component stream 112, the heated second component stream 116 and the ambient third component stream 118 to produce the temperature-controlled humidified gas stream 100. The merging step is preferably performed in a mixing zone 130. The mixing zone 130 is in fluid communication with the humidification device 122, the heating device 128 and the separation sub-system 120. In one aspect, the mixing zone 130 is disposed downstream of each of the separation sub-system 120, the humidification device 122 and the heating device 128. In an exemplary embodiment, the mixing zone 130 merges the first, second and third component streams 112, 116, 118, in any order, to produce the temperature-controlled humidified stream 100. In one embodiment, a thermocouple (not shown) is disposed downstream of the mixing zone 130 to monitor and control the temperature of the temperature-controlled humidified stream 100.

Because a preferred embodiment of the inventive system merges the heated second component stream 116 and the ambient third component stream 118 to control temperature, the resultant temperature-controlled humidified stream 100 can have a target temperature range that is significantly broader than a system that only utilizes a heated stream and/or an ambient stream. If only a heated stream were provided for temperature control, the system could not produce a temperature-controlled humidified stream 100 having a relatively low temperature. Conversely, if only an ambient stream (or even a cooled stream) were provided, the system could not produce a temperature-controlled humidified stream 100 having a relatively high temperature. Generally, gases at higher temperatures are capable of holding more water vapor than gases at lower temperatures. Hence, it may be desired to combine the humidified

first component stream 112 with the heated second component stream 116 prior to merging the resulting stream with the third component stream 118, which preferably is cooler than the first and second component streams 112, 116. Of course, the streams may be merged in any order depending on the desired temperature and humidity level. Thus, in one exemplary embodiment, the mixing zone 130 merges the humidified first component stream 112 with the heated second component stream 116 to produce an intermediate stream, which is heated due to the second component stream 116 and humidified due to the first component stream 112. In the same exemplary embodiment, the mixing zone 130 merges the intermediate stream with the third component stream 118 to produce the temperature-controlled humidified gas stream 100. By merging the humidified first component stream 112 with the heated second stream 116 before merging with the ambient third component stream 118, condensation of the water vapor into liquid water is minimized.

In the alternative, the mixing zone 130 merges the first, second, and third component streams 112, 116, 118 in any order.

In preferred embodiments, the components in the system are capable of withstanding a pressure of at least 75 psi (5.27 kg/cm), e.g., at least 100 psi (7.03 kg/cm), at least 110 psi (7.73 kg/cm), or at least 130 psi (9.14 kg/cm). In some of the preferred embodiments, the lines and fittings of the system are made of 316 stainless steel or Teflon™. The output fittings and lines may be made of Teflon™ because it provides a low thermal mass and permits a rapid temperature response.

In one embodiment, the process further comprises the step of calculating a target amount of water vapor necessary to achieve a target humidity in the temperature- controlled humidified stream 100. In one aspect, this step is performed by a humidity control system 132. The target amount of water vapor is the quantity of water vapor necessary to produce the target humidity in the temperature-controlled humidified stream 100. The target amount of water vapor is based on psychrometric calculations involving the target humidity and flow rate for the resultant temperature-controlled humidified stream 100. Typical psychrometric calculators known in the art can be utilized to calculate the target amount of water vapor. One such psychrometric calculator is a computer software package. In another embodiment, the target humidity is set by an

outside source. In still another embodiment, the target humidity is set by an operator. In the alternative, the target humidity is set by a computer software package.

As the temperature inside the humidifying bottle 124 increases, the rate at which water vapor permeates through the humidity tubing 126 and into the first component stream 112 also increases. In an exemplary embodiment, once the temperature of the humidifying bottle 124 is measured (e.g., via a thermocouple) and the target amount of water vapor is known, the humidity control system 132 performs the step of adjusting the flow rate of the first component stream 112, according to additional calculations, such that the target amount of water vapor is introduced into the first component stream 112 via the humidification tubing 126 inside the humidity bottle (or by other humidification means). At this point, the first component stream 112 will contain the water vapor that will humidify the temperature-controlled humidified stream 100 produced by the merging of the first, second and third component streams 112, 116, 118. In one preferred embodiment, because the humidity control system 132 adjusts the flow rate of the first component stream 112, it is in communication with the separation sub-system 120.

In one exemplary embodiment, the selected target humidity ranges from 1 % to 100%, e.g., 5% to 100%, 25% to 100%, or 50% to 100%.

In another exemplary embodiment, the humidity control system 132 is capable of increasing the humidity of the temperature-controlled humidified stream 100 by at least 25% in 15 seconds, e.g., at least 50% in 15 seconds, or at least 75% in 15 seconds. In another exemplary embodiment, the humidity control system 132 is capable of decreasing the humidity of the temperature-controlled humidified stream 100 by at least 25% in 15 seconds, e.g., at least 50% in 15 seconds, at least 75% in 15 seconds, or at least 90% in 15 seconds. In another exemplary embodiment, the humidity control system 132 is capable of increasing the humidity of the temperature-controlled humidified stream at a rate of up to 5% per second, e.g., up to 3.3% per second, or up to 1.3% per second. In another exemplary embodiment, the humidity control system 132 is capable of decreasing the humidity of the temperature-controlled humidified stream at a rate of up to 5% per second, e.g., up to 3.5% per second, or up to 2.0% per second.

In one embodiment, the process further comprises the step of adjusting the flow rate of at least one of the second and third component streams 116, 118 based on temperature information of the temperature-controlled humidified gas stream 100. As a result, the temperature of the temperature-controlled humidified gas stream 100 approaches the target temperature. In one aspect, this step is performed by a temperature control system 134. In an exemplary embodiment, the temperature control system 134 adjusts either or both of the second and third component streams 116, 118. The starting temperature of the temperature-controlled humidified stream 100 optionally is measured as the temperature-controlled humidified stream 100 exits the mixing zone 130. The temperature control system 134 preferably compares the starting temperature to the target temperature and adjusts the flows of the second and third component streams 116, 118 using a feedback loop. In one preferred embodiment, because the temperature control system 134 can adjust the flow rates of the second and third component stream 116, 118, it is in communication with the separation sub-system 120. As an example, if the starting temperature is less than the target temperature, the flow rate of the heated second component stream 116 is increased and the flow rate of the ambient third component stream 118 is decreased accordingly. As another example, if the starting temperature is greater than the target temperature, the flow rate of the ambient third component stream 118 is increased and the flow rate of the heated second component stream 116 is decreased accordingly.

In one embodiment, the step of adjusting the flow rate of at least one of the second and third component streams 116, 118 based on temperature information of the temperature-controlled humidified gas stream is performed along with the steps of calculating a target amount of water vapor and adjusting the flow rate of the first component stream 112, according to additional calculations, such that the target amount of water vapor is introduced into the first component stream 112. In another embodiment, the steps of calculating a target amount of water vapor and adjusting the flow rate of the first component stream 112, according to additional calculations, such that the target amount of water vapor is introduced into the first component stream 112 is performed without performing the step of adjusting the flow rate of at least one of the

second and third component streams 116, 118 based on temperature information of the temperature-controlled humidified gas stream.

In one exemplary embodiment, the selected target temperature can range from 1O ⁰ C to 100°C, e.g., 10 ⁰ C to 90 ⁰ C, 25°C to 90 ⁰ C, or 25°C to 75°C. In another exemplary embodiment, the temperature control system 134 is capable of increasing the temperature of the temperature-controlled humidified gas stream 100 by at least 20 ⁰ C e.g., at least 25°C, at least 3O ⁰ C, or at least 5O ⁰ C. In another exemplary embodiment, the temperature control system 134 is capable of decreasing the temperature of the temperature-controlled humidified gas stream 100 by at least 10°C, e.g., at least 15 ⁰ C, at least 20 ⁰ C ₅ or at least 25°C.

In another exemplary embodiment, the temperature control system 134 is capable of increasing the temperature of the temperature-controlled humidified stream at a rate of up to 0.50 ⁰ C per second, e.g., up to 0.44 ⁰ C per second, or up to 0.22 ⁰ C per second. In another exemplary embodiment, the temperature control system 134 is capable of decreasing the temperature of the temperature-controlled humidified stream at a rate of up to 0.30 ⁰ C per second, e.g., up to 0.20 ⁰ C per second, or up to 0.10 ⁰ C per second.

In one embodiment, the process further comprises the step of inhibiting water (vapor and/or liquid) in the humidifying bottle from 124 back flowing. As the system operates pressure differences can force water out of the humidifying bottle 124 and back into the mass flow controller. This water can have a detrimental effect on the performance and product life of the mass flow controller. In an exemplary embodiment, the system utilizes a water trap 136 to perform this step. As shown, the water trap 136 is disposed between the mass flow controller 121a and the humidifying bottle 124.

The present invention will be better understood in view of the following non- limiting examples. Example 1

Figures 2 and 3 show temperature and humidity data for a sample stream of gas processed through the inventive system of FIG. 1. Initial gas flow was set at 10 liter per minute. The temperature of the humidifying bottle was set to approximately 82 ⁰ F. The initial stream was at approximately 55 ⁰ C and 25 % relative humidity (as shown from 1780 seconds to approximately 1910 seconds).

Referring to Figure 2, at approximately 1910 seconds, the target temperature was set to approximately 75°C. The total response time for the sample stream of temperature- controlled humidified gas to achieve the target temperature was approximately 90 seconds. Referring to Figure 3, at approximately 1910 seconds, the target humidity was set to approximately 75%. The total response time for the sample stream of temperature- controlled humidified gas to approach the target humidity was approximately 25 seconds, which included 10 seconds for the gas to reach the sensor once the target humidity was set. It should be noted that the humidity sensor takes some time to stabilize its measurements and produce accurate readings. Example 2

Figures 4 and 5 show temperature and humidity data for a sample stream of gas processed through the inventive system of FIG. 1. Initial gas flow was set at 10 liter per minute. The temperature of the humidifying bottle was set to approximately 82°F. The initial stream was at approximately 40°C and 50% relative humidity (as shown from 402 seconds to approximately 428 seconds).

Referring to Figure 4, at approximately 432 seconds, the target temperature was set to approximately 70°C. The total response time for the sample stream of temperature- controlled humidified gas to achieve the target temperature was approximately 68 seconds.

Referring to Figure 5, at approximately 426 seconds, the target humidity was set to approximately 70%. The total response time for the sample stream of temperature- controlled humidified gas to approach the target humidity was approximately 54 seconds, which included 10 seconds for the gas to reach the sensor once the target humidity was set. It should be noted that the humidity sensor takes some time to stabilize its measurements and produce accurate readings. Example 3

Figures 6 and 7 show temperature and humidity data for a sample stream of gas processed through the inventive system of FIG. 1. Initial gas flow was set at 10 liter per minute. The temperature of the humidifying bottle was set to approximately 82°F. The

initial stream was at approximately 55°C and 100% relative humidity (as shown from 1507 seconds to approximately 1535 seconds).

Referring to Figure 6, the target temperature was maintained at 55 ⁰ C. The sample stream of temperature-controlled humidified gas changed a maximum of approximately 7 ⁰ C as the humidity of the sample stream of temperature-controlled humidified gas was dropped from 100% to 25%.

Referring to Figure 7, at approximately 1535 seconds, the target humidity was set to approximately 25%. The total response time for the sample stream of temperature- controlled humidified gas to approach the target humidity was approximately 30 seconds, which included 15 seconds for the gas to reach the sensor once the target humidity was set.

Any feature described or claimed with respect to any disclosed implementation may be combined in any combination with any one or more other feature(s) described or claimed with respect to any other disclosed implementation or implementations, to the extent that the features are not necessarily technically incompatible, and all such combinations are within the scope of the present invention. Furthermore, the claims appended below set forth some non-limiting combinations of features within the scope of the invention, but also contemplated as being within the scope of the invention are all possible combinations of the subject matter of any two or more of the claims, in any possible combination, provided that the combination is not necessarily technically incompatible.