Patent Application
20150176914
1. Statement of the Technical Field
The invention concerns a condenser assembly, and more particularly systems and methods which include direct contact mixing and separation of working fluids and the creation of desired fluid states.
2. Description of the Related Art
Heat engines and the like use energy provided in the form of heat to perform mechanical work. In most systems, a condenser is included to condense the working fluid after it has been vaporized and expanded. By condensing the working fluid, it changes at least a portion of the working fluid back into a liquid which may be returned to a boiler or the like of the system. This allows clean and treated condensate to be reused and it is generally easier to pump liquid than vapor. It is desirable to increase the efficiency of the cycle by optimally balancing the temperature, pressure and mass flow rate between the boiler and the condenser.
The unique embodiment of the general concept relies on the ability to not fully condense 100 percent of the working fluid subsequent to performing work. Traditional Rankine cycles require 100 percent condensing. The invention incorporates methods enabling a useful portion of the working fluid, remaining in a vapor state, to pass thru the condensing means, being useful to aid in the separation process more efficiently than the prior art of full condensation as defined by current cycle architectures.
Embodiments of the invention concern a method of separating a liquid portion of a working fluid from a vaporous flow of the working fluid. The method includes the steps of directing a liquid portion of the working fluid which has previously been separated through a chiller such that said portion of the first working fluid is cooled to define a cooling fluid; spraying the cooling fluid into the vaporous flow of the working fluid with a resultant cooled vaporous working fluid; and passing the cooled vaporous working fluid through a separator whereby at least a portion of the working fluid is separated out of the cooled vaporous working fluid in liquid form.
The invention also includes a system for separating a liquid portion of a working fluid from a vaporous flow of the working fluid. The system includes a separator having a body and defining a reservoir for a liquid portion of the working fluid to collect. A chiller is configured to cool a previously separated liquid portion of the working fluid drawn from the reservoir to define a cooling fluid. A sprayer is positioned relative to the separator and configured to spray the cooling fluid into a flow of the vaporous working fluid before the vaporous working fluid reaches the separator.
Embodiments will be described with reference to the following drawing figures, in which like numerals represent like items throughout the figures, and in which:
The invention is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operation are not shown in detail to avoid obscuring the invention. The invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the invention.
The invention concerns a condenser assembly 210 for use in a Hybrid Thermal Cycle (HTC), or other energy transfer operations utilizing fluids F1, F2, and F3 where F3 is comprised of a mixture of fluids F1 and F2. The F1 fluid is a fluid construct that is advantageously selected so that it is capable of transitioning from a liquid to a vapor in some parts of the cycle, and from a vapor to a liquid during other portions of the cycle. Fluid F2 is preferably selected so that it remains vaporous throughout the cycle. The F1 fluid is mixed with the F2 fluid in parts of the cycle to form the F3 fluid. Later in the cycle the F1 fluid is separated from the F3 fluid. Following a compression portion of the cycle during which F2 is compressed, there is an expansion part of the cycle during which F3, comprised of a mixture of F1 and F2, is expanded. During this expansion, the F1 fluid functions to support or maintain the temperature of the F2 fluid, preventing it from cooling more rapidly than without the latent heat that is available from the F1 fluid. If the F2 fluid were expanded without the portion of the F1 fluid it would cool more rapidly, having less capacity to perform work. This characteristic or effect in the cycle is desirable as it enables the fluid mixture F3 to perform work for a longer period of time during expansion. This ability of F1 to effectively delay the cooling of F2 essentially ends when the F1 fluid reaches a point where it transitions from a vapor back into a liquid. At the end of the expansion process, at least a portion of the F1 fluid condenses out of the F3, leaving a residual portion, which is F2.
An exemplary heat engine 200 incorporating the condenser assembly 210 is illustrated in
The heat engine 200 makes use of a high temperature thermal source 225 and optionally a low temperature thermal source 227. The “high temperature” nomenclature which is used to describe thermal source 225 is intended to emphasize that such thermal source is at a higher temperature as compared to the temperature of low temperature thermal source 227. Although thermal source 225 will have a higher temperature compared to low temperature thermal source 227, it should be appreciated that high temperature thermal source 225 can actually have a relatively low temperature as compared to those temperatures which are normally used to provide efficient operation of a conventional heat engine. For example, in some embodiments, the high temperature thermal source 225 may actually only have a temperature of about 800° F. or less. In other embodiments, the high temperature thermal source 225 can have a temperature of about 400° F. or less. The ability to efficiently utilize such sources of heat is a significant advantage of the present invention.
Suitable choices for working fluids F1 and F2 will be described below in further detail. Still, given the anticipated temperatures for thermal source 225, 227, it can be advantageous to select the working fluid F1 to be a low vapor state formulation to facilitate vaporization of such working fluid at relatively low temperatures. Examples of such low vapor state formulations can include fluids such as methanol or pentane.
A high pressure boiler 203 can use as its primary heat source a supply of steam from the high temperature thermal source 225. For example, the high temperature thermal source can be a geothermal well or waste heat from some high temperature process or other power generation system. The low temperature thermal source can be a thermal source that is entirely independent of the high temperature thermal source 225. However, it can be advantageous to select the optional low temperature thermal source 227 to be a down-line flow from the high temperature thermal source 225, after such flow has provided a portion of its thermal energy to the high pressure boiler 203, as illustrated in
The exemplary heat engine 200 also includes a low pressure boiler 207. The high pressure boiler 203 will generally have a higher internal operating pressure as compared to the optional low pressure boiler 207. However, it should be appreciated that high pressure boiler 203 can actually have a relatively low pressure as compared to those operating pressures which are normally used to provide efficient operation of a conventional heat engine. For example, in conventional heat engines, high pressure boilers typically are understood as boilers that operate in the range of 1000 to 3000 psi. In contrast, the high pressure boiler 203 can operate at a pressure in the range of 300 psi or less. Still, the invention is not limited in this regard and the actual operating pressure in the high pressure boiler 203 and optional low pressure boiler 207 can vary in accordance with the available heat source and other design conditions.
Referring again to
A second flow F1(2) of a first liquid working fluid F1 is pressurized using a pump 201b. It is understood that the pumps 201a and 201b may combined in a single pump. The pressurized fluid is communicated to the high pressure boiler 203 which is maintained at a relatively high temperature as determined by high temperature thermal source 225. The high pressure boiler 203 will add a predetermined amount of thermal energy to the F1(2) working fluid. As a result of these operations, the F1(2) working fluid is converted to a vapor (sometimes referred to herein as F1(2) vapor).
The F1(2) vapor formed in high pressure boiler 203 is communicated to an expander 209 where the thermal energy contained in the F1(2) vapor is used to perform work. Still, a designer may choose to omit the expander 209 in some embodiments. The F1(2) vapor, after exiting the expander 209, still contains high quantities of thermal energy, and is therefore communicated to the mixing chamber 206.
The F1(1) and F1(2) flow of F1working fluid vapor are communicated to the mixing chamber 206. Within the mixing chamber 206, F1(2) vapor and the F1(1) vapor are mixed with a vaporous flow of working fluid F2 which has been compressed in compressor 204. In the example provided, the compressor 204 is powered by the expander 209. These three separate vaporous fluid flows comprised of F1(1), F1(2) and F2 are combined or mixed to form a vaporous mixture which is referred to herein as third working fluid F3 (or F3 vapor). Due to this mixing of the working fluids, the transfer of thermal energy between the fluids is facilitated. In some embodiments, additional thermal energy can optionally be provided from an independent source to the F3 vapor contained in the mixing chamber 206. For example, the additional thermal energy can be provided to the mixer from a source that is external to the system shown in
It is not necessary for all thermal energy transfer between the F1(1), F1(2) and F2 vapor to occur within the mixing chamber 206. In some embodiments of the invention, a portion of such transfer can occur after the F3 vapor exits the mixing chamber. For example, in an embodiment of the invention, at least a portion of such transfer can continue occurring as the F3 vapor continues through an expansion cycle discussed below. Also, it is possible for the F1(1), F1(2) vapor, and the F2 vapor fluids to enter the mixer at approximately the same temperatures and pressures. However, as a result of the different chemical compositions of such fluids, transfer or exchange of thermal energy as between them, can still potentially take place in a subsequent expansion cycle. Details of the expansion cycle are discussed below with regard to expander 208.
The vaporous third working fluid F3 is communicated under pressure from the mixing chamber 206 to expander 208 for performing useful work. Well known conventional expander technology can be used for purposes of implementing expander 208, provided that it is capable of using a pressurized vapor to perform useful work. For example, the expander 208 can be an axial flow turbine, custom turbo-expander, vane expander or reciprocating expander. Advantageously the expander 208 will be selected by those skilled in the art to provide high conversion efficiency based on the specific thermodynamic and fluid properties of F3 delivered to the expander for a particular embodiment of the cycle. Still, the invention is not limited in this regard.
After such work is performed by the expander 208, the F3 working fluid is communicated from the expander to a condenser assembly 210 including a condenser 212. The condenser assembly 210 includes at least three ports. Port 221 is used to receive the F3 working fluid provided to the condenser. Port 222 is used to communicate Fl working fluid condensate (F1 liquid) out of the condenser, and thereafter to pump 201 for re-use within the system. Port 223 is used to communicate a vaporous flow of the residual portion of F3 to the compressor 204 where it is re-used, being identified as the F2 working fluid.
As is well known in the art, condensing is commonly performed by cooling the working fluid under designated states of temperature and pressure. This cooling process will generally involve a release of latent heat contained in the third working fluid F3. The condenser cools the F3 fluid and thereby facilitates the condensing of the F1 fluid contained within the F3 fluid mixture. The F1 portion therefore drops out as a liquid in the form of condensate 219, and is collected in the condenser as F1 fluid (liquid), and is available for reuse. This process leaves a residual portion of the F3 working fluid. The residual portion of F3 is a remaining portion of the one or more fluids previously comprising F3 that exist after the F1 condensate has been extracted from F3. With the F1 (liquid) condensate and the residual portion of F3 available as the F2 working fluid, the process has essentially returned to its starting point. Thereafter, the entire process described above can be repeated in a continuous cycle.
The performance of the condenser 212 is reliant on many factors, including the properties of the constituent fluids, the flow rates of the fluids, the ratios of the fluids, the condenser pressure and temperature, and hardware or apparatus physical configuration. These are all common variables that are well understood by those skilled in the art of condenser designs. The temperature and pressure conditions inside the condenser 212 are chosen so that the F1 constituent part of F3 is converted to a condensate within the condenser, while the second working fluid F2 is not condensed. In other words, a residual portion of F3 will remain in a vaporous state. Those skilled in the art will appreciate that this condensing process applied for purposes of separating F1 from the residual portion of F3 can be accomplished by choosing the first and second working fluid to have different thermal properties. Under some operational parameters it is possible to have the F1, F2 and therefore the F3 fluids all be the same fluid. In this case, simply a portion of the overall flow is converted back and forth between liquid and vapor states.
In conventional Rankine cycle heat engines, the condensers can often be the most constraining part of the system. This is because it is necessary to completely condense 100% of the vapor that comprises the working fluid. Because of the difficulty in accomplishing 100% condensate, many systems will bleed a portion of the working fluid outside of the main system. This bleed process may include directly releasing working fluid to the atmosphere or to an independent reservoir that is outside of the primary condenser of the system. A key advantage of the current invention is the ability to not require a full condensate process. Accordingly, condenser 212 may not actually condense 100% of F1 from the vaporous F3 mixture. Advantageously, this condition is acceptable for purposes of the present invention, and a portion of F1 can be permitted to remain mixed within a residual portion of F3. For purposes of the present description, any portion of the residual F1, either in the vapor or liquid form (carried in the fluid stream), after the condensing process, therefore remaining in F2, can be considered a constituent of F2 by design.
The present invention can include several possible configurations with respect to the overall condenser assembly 210. In a first embodiment illustrated in
Port 221 receives the F3 working fluid from the expander 208 and, prior to entering the separator 212, the F3 working fluid is exposed to a cooled fluid spray F1(cooled) provided via nozzle 234 or some other form of sprayer. Providing the cooled fluid F1(cooled) as a spray of droplets allows the fluid to quickly combine with and cool the F3 working fluid.
The F1 working fluid within the separator 212 is used to produce the cooling spray. To facilitate such, a portion of the F1 fluid is drawn through port 224 by a pump 231 or the like to an external chiller 230. The F1 fluid passes through the external chiller 230 and across a coolant 232 whereby heat is removed to the external environment as indicated at 235 and the cooled fluid F1(cooled) exits the chiller 230. The coolant 232 can be a natural source of coolant (e.g. ambient air or cool water) or any other source of coolant (e.g. a cold side of a refrigerant loop). The cooled fluid F1(cooled) travels to the nozzle 234 and is sprayed into and combines with the F3 working fluid with the combined fluid F3(cooled) then entering the centrifugal separator 212. This method can be advantageous, as direct contact cooling could reduce the cost of systems relative to the use of heat exchangers that require large contact areas comprising copper or similar coils or finned surfaces.
Referring to
The residual vapor flow passes from the wet zone 247 to the dry zone 257 through the one or more through passages 250 through the support wall. Additional liquid may drop out of the overall flow in the dry zone where this liquid condensate accumulates and is removed at 222b. The process that starts from 221 and ends at the dry zone 257 may be repeated in some embodiments making it a two stage separator further increasing the time of contact of the fluid on the surfaces of the cylindrical body 240 before the residual portion of F3 exits through the port 223. This further maximizes the amount of F1 working fluid which condenses out of the F3 working fluid.
The F1 liquid working fluid and the F3 residual fluid (F2) then proceed as described with reference to
A condenser assembly 210′ in accordance with another alternative embodiment is shown in
Referring to
In this embodiment, the first cooling of the inbound flow is followed by spraying the residual flow, which in some applications will prove to increase the capacity to remove additional condensate from the flow. With the ability to place the cooling in the most advantageous locations relative to the return flow F3, the condensing operation can be tailored to the overall system needs.
In the examples provided the use of the internal cooling loop and spraying the inbound F3 flow has been shown. It is possible to have a configuration similar to
It can be observed from the examples provided, there are many combinations of the spray locations, cooling locations and separation locations that could be configured for a specific application. It is the intent of this invention to show that by having the inherent capacity to pass a volume of the residual F3 flow through the condenser assembly 210, this overall process enables many methods of forming condensate form the initial inbound flow of F3, that are not afforded by the current art.
The specifics of a particular condenser assembly design are reliant on many factors, including the properties of the constituent fluids, the flow rates of the fluids, the ratios of the fluids, the condenser pressure and temperature, and hardware or apparatus physical configuration. These are all common variables that are well understood by those skilled in the art of condenser designs.
The first and second working fluids, and ratios thereof, should also be selected such that they work in concert with one another. In particular, the more rapid cooling of the second fluid (as compared to the first fluid) during the expansion process can facilitate the exchange of energy from the first fluid to the second fluid. This leaves the first fluid very close to the vapor to liquid transition point as it approaches the end of the expansion cycle. As the first working fluid condenses, it is therefore separated from the second working fluid and can be collected in the condenser. This unique fluid capability provides the means to tune the thermal take-up rates (heat addition/vaporization) and additionally the drop-out rates (condensate rates) of the fluids in operation.
Various examples of the operation of exemplary heat engine are provided in applicant's co-pending U.S. application Ser. No. 13/098,603, filed May 2, 2011; Ser. No. 13/239,674, filed Sep. 22, 2011; Ser. No. 13/477,394, filed May 22, 2012; Ser. No. 13/533,497, filed Jun. 26, 2012; and Ser. No. 13/556,387, filed on Jul. 24, 2012, each of which is incorporated herein by reference.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
All of the apparatus, methods and algorithms disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the invention has been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus, methods and sequence of steps of the method without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain components may be added to, combined with, or substituted for the components described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined.
