Patent Publication Number: US-2023146332-A1

Title: Turbocharged compressor

Description:
BACKGROUND 
     Compressors are mechanical devices that increase the pressure of a fluid (e.g., air) by reducing the volume of said fluid. The temperature of the fluid increases as it is compressed. 
    
    
     
       DRAWINGS 
       The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items. 
         FIG.  1    is a perspective view illustrating a turbocharged fluid compressor system having a waste recovery system in accordance with example embodiments of the present disclosure. 
         FIG.  2    is a schematic view of a turbocharged fluid compressor system, such as the turbocharged fluid compressor system shown in  FIG.  1   , including a contact-cooled compressor having a coolant circulation system. 
         FIG.  3    is a schematic view of a turbocharged fluid compressor system including a coolant-free compressor having a first compression stage and a second compression stage in accordance with example embodiments of the present disclosure 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the subject matter, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the subject matter is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the subject matter as described herein are contemplated as would normally occur to one skilled in the art to which the subject matter relates. 
     Overview 
     Fluid compressor systems are widely used in a variety of industries such as in construction, manufacturing, agriculture, energy production, etc. As fluid compressors compress a working fluid, heat is produced as a result of the pressure increase in the working fluid. This heat is not only a waste of energy but also a waste of money for the users. Some systems use a portion of this heat waste in energy recovery systems that deliver hot water as a byproduct, but not all compressor users have a need for hot water. 
     Accordingly, the present disclosure is directed to a turbocharged fluid compressor system having a waste heat recovery system that increases the efficiency of a fluid compressor system by recovering heat produced in the compression process and using it to power a turbine section in a turbocharger. The turbocharged fluid compressor system can be used with any type of fluid compression device and should not be limited to the illustrative fluid compressor system shown in any of the accompanying figures. The term “fluid” should be understood to include any compressible fluid medium that can be used in the fluid compressor system as disclosed herein. It should be understood that air is a typical working fluid, but different fluids or mixtures of fluid constituents can be used and remain within the teaching of the present disclosure. Therefore, terms such as fluid, air, compressible gas, etc. can be used interchangeably in the present disclosure. For example, in some embodiments it is contemplated that ambient air, a hydrocarbon gaseous fuel including natural gas or propane, or inert gases including nitrogen or argon may be used as a primary working fluid. 
     The waste heat recovery system may comprise an organic Rankine cycle (ORC) system operating with an organic compound. One benefit of using an organic compound in a Rankine cycle system is that it allows the recovery of heat from relatively low temperature sources such as in the case of industrial waste heat. It should be understood that the terms “organic compound” and “organic fluid” are used interchangeably herein to describe an organic, high molecular mass fluid, having a boiling point at a lower temperature than the boiling temperature of water. Although an ORC system is discussed herein, it should be understood that the working fluid for the Rankine Cycle in the waste heat recovery system may be water, or another fluid (e.g., having a low molecular mass) not classified as an organic compound. The working fluid of the Rankine Cycle may have a boiling point at a lower, higher, or equal to the boiling temperature of water. 
     The ORC system includes a pump to move the organic fluid within the system. At least one evaporator evaporates the organic fluid in the system, which is then directed to the turbocharger. In the ORC system described, the turbine section of the turbocharger acts as an expander device to expand the organic fluid vapor and drive a compressor section of the turbocharger. After the organic fluid vapor exits the turbocharger, it is directed to a condenser. The condenser condenses the organic fluid vapor, which is pumped by a pump back into the at least one evaporator to restart the cycle. 
     The compressor section of the turbocharger pre-compresses a working fluid (e.g., ambient air) before entering the fluid compressor system. The working fluid may flow through a filter device before entering the compressor section of the turbocharger. The fluid compressor system may include a positive displacement compressor such as a rotary screw compressor or a reciprocating compressor, or a dynamic compressor such as a centrifugal compressor or an axial compressor. The fluid compressor system can include a compressor with multi-stage compression or a compressor with single stage compression. Other forms and configurations of compression devices are also contemplated herein. 
     As the working fluid is compressed in the fluid compressor system, the temperature of the working fluid increases. In example embodiments, the hot working fluid may be directed to the at least one evaporator of the ORC system, where the waste heat of the working fluid is used to evaporate the organic fluid of the ORC system that powers the compressor section of the turbocharger. By using a pre-compressed fluid at an inlet of the fluid compressor system, the power consumption of the fluid compressor system improves. Thus, the efficiency of the fluid compressor system (e.g., the compressor section of the turbocharger) is improved by recovering a portion of the waste heat produced as a by-product of the working fluid&#39;s pressure increase. Additional benefits include but are not limited to a lower pressure ratio across an airend&#39;s inlet and outlet, which results in reduced internal leaking, and lower cooling loads entering the fluid compressor&#39;s cooling sections, both of which further improve the efficiency of the fluid compressor system. 
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Referring generally to  FIGS.  1  through  3   , turbocharged fluid compressor systems are described. Turbocharged fluid compressor system  100  includes a waste heat recovery system  102  and a fluid compressor system  104 . Waste heat recovery system  102  includes a turbocharger  110  having a turbine section  112  and a compressor section  114 . Waste heat recovery system  102  further includes a pump  106 , at least one evaporator  108 , and a condenser  116 . 
     Pump  106  moves a waste heat recovery fluid through the waste heat recovery system through the at least one evaporator  108 , where it evaporates into waste heat recovery vapor. The waste heat recovery vapor enters the turbine section  112  of the turbocharger  110 . The turbine section  112  extracts energy from the waste heat recovery vapor and converts it into kinetic energy, driving the compressor section  114  of the turbocharger  110 . As the waste heat recovery vapor exits the turbocharger  110 , it is directed to the condenser  116 , where it condenses. 
     As shown, the fluid compressor system  104  includes an inlet air filter  118 , a primary motive source  90 , an airend  120 , and an after cooler  124 . Inlet air filter  118  filters the incoming working fluid (e.g., ambient air) prior to entering the pre-compression stage at the compression section  114  of the turbocharger  110 . As the working fluid is pre-compressed, its temperature increases. A heat dissipating device such as finned tube  122  shown may be installed between the pre-compression stage at compression section  114  and airend  120 . Finned tube  122  enables cooling of the working fluid and minimizes a drop in pressure. It should be understood that other types of heat dissipating devices for lowering the temperature of the working fluid without reducing the pressure accumulated during the pre-compression stage may be used instead. For example, the heat dissipating device may be a tube with integral external fins, a tube with integral internal fins, a tube with a static mixer insert, etc. 
     The working fluid is further compressed in the airend  120 . Primary motive source  90  is operable for driving the airend  120  via a drive shaft. Primary motive source may be an electric motor, an internal combustion engine, a fluid-driven turbine, or the like. Airend  120  increases the pressure of the working fluid, which also increases the temperature of the working fluid as a result. This hot working fluid is directed to the at least one evaporator  108 , where the waste heat is used to evaporate the waste heat recovery fluid flowing through the waste heat recovery system  102 . Upon leaving the at least one evaporator  108 , the pre-cooled working fluid flows into an after cooler  124 , where its temperature is further reduced prior to delivery. 
     With respect to  FIG.  1   , an example embodiment of a turbocharged fluid compression system  100  is shown. A structural base  50  can be configured to support at least portions of the turbocharged fluid compression system  100 . In example embodiments, the turbocharged fluid compression system  100  is not supported by structural base  50 , with the different components forming the turbocharged fluid compression system  100  being installed separately and being connected through the respective piping. An inlet ORC fluid manifold and an outlet ORC fluid manifold (not shown) may supply the ORC system with the ORC fluid needed. 
       FIG.  2    is a schematic of the example embodiment of the turbocharged fluid compression system  100  shown in  FIG.  1   . The fluid compressor system  104  includes a contact-cooled airend  120  having a coolant circulation system  136 . For example, a coolant circulated by the coolant circulation system  136  used in the turbocharged fluid compressor system  100  may be oil, water, or any other coolant used in contact-cooled compressor systems. In the contact-cooled airend  120 , coolant is injected into compression cavities within the airend to aid cooling of the working fluid. A discharge stream of pressurized working fluid and coolant mixture is discharged from the contact-cooled airend  120  at a high temperature. The discharge stream is directed to a separator tank  126 , where the coolant is separated from the working fluid. The coolant-free working fluid is cooled at the after cooler  124  located downstream from the separator tank  126  prior to exiting through an outlet  134  towards an end use machine, a compressed fluid system, or a storage tank (not shown). 
     After being separated from the working fluid and discharged from the separator tank  126 , the hot coolant is directed to a primary temperature control valve (TCV)  130 . The primary TCV  130  is further connected to the contact-cooled airend  120 , the at least one evaporator  108 , and a secondary TCV  132 . The primary TCV  130  can control and selectably direct the coolant flow in the coolant circulation system towards the at least one evaporator  108  or the airend  120  based on the desired temperature of the coolant flow. The primary TCV  130  directs the hot coolant discharged from the separator tank  126  to the at least one evaporator  108 , where the organic fluid absorbs the waste heat in the coolant. The at least one evaporator  108  may be a brazed plate heat exchanger, but any other type of heat exchanger may be used to absorb heat from the hot coolant and evaporate the organic fluid according to example embodiments of the present disclosure. In example embodiments, the turbocharged fluid compressor system may have a different number of TCVs and is not limited to having a primary and a secondary TCV. For example, a turbocharged fluid compressor system may have one TCV or may not include any TCVs. 
     As the cooled coolant exits the at least one evaporator  108 , it flows into the secondary TCV  132 . The secondary TCV  132  selectably directs the cooled coolant to a cooler  128  for further cooling or back into the airend  120  through the primary TCV  130 , depending on the desired temperature of the coolant prior to entering the airend  120 . Since the majority of the hot coolant&#39;s heat is absorbed in the at least one evaporator  108 , a smaller cooler  128  may be used in place of larger coolers in typical contact-cooled compressor systems. The space saved from the use of the smaller cooler  128  may be used to accommodate other elements of the turbocharged fluid compressor system  100  (e.g., the condenser  116 ) without significantly increasing the size of the turbocharged fluid compressor system  100  compared to other fluid compressor systems. 
     Example embodiments of the turbocharged fluid compressor system  100  may also include a heat waste recovery system  102  that further recovers waste heat from the compressed working fluid prior to entering the aftercooler  124 , and not only recovers the waste heat from the coolant ejected from the airend  120 . In example embodiments, the at least one evaporator  108  recovers the waste heat from the discharge stream containing the working fluid and coolant mixture prior to entering the separator tank  126 . 
     The turbocharged fluid compression system  100  may include a controller (not shown) operable for controlling the primary motive source  90 , pump  106 , valves and fluid control mechanisms (e.g., the primary and secondary TCVs), the waste heat recovery system  102  and the fluid compressor system  104 . 
     When the turbocharged fluid compressor system  100  is switched on, the controller starts the primary motive source  90 , which drives the airend  120 . The airend  120  starts delivering the pressurized stream of working fluid and coolant. As the discharge stream of pressurized coolant and working fluid discharged by the airend  120  builds up in the separator tank  126 , coolant separates from the working fluid in the separator tank. As the temperature of the working fluid increase, the coolant&#39;s temperature increases. The primary TCV  130  selectably lets the hot coolant flow into the cooler  128 . Depending on selected temperature parameters, as the coolant reaches a specific temperature, the pump  106  in the ORC system  102  starts pumping organic fluid. Preferably, a coolant temperature threshold at which the pump  106  starts pumping organic fluid is higher than the coolant temperature threshold at which the primary TCV sends the separated coolant into the cooler  128 . While the coolant temperature does not reach the coolant temperature threshold required to start the ORC system  102 , the coolant is cooled by the cooler  128  prior to recirculating into the airend  120 . 
     In example embodiments, the contact-cooled airend may include more than one airend stage. An intercooler may be disposed between each of the airend stages to cool the pressurized working fluid and coolant mixture before entering the next airend stage to be further pressurized. The turbocharged fluid compression system  100  is not limited to having only one airend  120 . 
       FIG.  3    is a schematic of an example embodiment of the turbocharged fluid compressor system  200 , where a coolant-free fluid compressor system  204  includes a coolant-free airend  220 . Coolant-free airend  220  includes a first airend stage S 1 , a second airend stage S 2 , an intercooler  222  and an aftercooler  224 . Other example embodiments of the coolant-free compressor system  204  may employ a different number of airend stages. Turbocharged fluid compressor system  200  includes two evaporators: a first evaporator  236 , located downstream from the first airend stage S 1 , acting as a pre-intercooler, and a second evaporator  238 , located downstream from the second airend stage S 2 , acting as a pre-aftercooler. 
     The organic fluid in ORC system  202  is moved by pump  206 . An organic fluid flow stream  207  is then split into a first flow stream  208  and a second flow stream  209 . The first flow stream  208  passes into the first evaporator  236 , where the organic fluid is evaporated. After splitting from the first flow stream  208 , the second flow stream  209  is directed to the second evaporator  238 , where the organic fluid is evaporated. First flow stream  208  and second flow stream  209  merge back together into the same organic fluid flow stream  207  upstream of the turbine section  212  of turbocharger  210 . The turbine section  212  extracts the energy from the organic fluid vapor and converts it into kinetic energy, driving the compressor section  214  of the turbocharger  210 . 
     The organic fluid is delivered from the turbine section  212  of the turbocharger  210  into condenser  216 , where it condenses. The organic fluid is pumped back by pump  206 , and splits prior to entering first evaporator  236  and second evaporator  238 , where it absorbs the waste heat from the working fluid as it exits the first compression stage S 1  and second compression stage S 2  respectively. 
     The working fluid is pre-compressed by compressor section  214  of turbocharger  210  prior to entering the first airend stage S 1  of coolant-free airend  220 . As the pressure of the working fluid is increased, its temperature increases. Upon leaving first airend stage S 1 , the working fluid enters the first evaporator  236 . The organic fluid in first evaporator  236  absorbs the waste heat from the working fluid, evaporating as a result. The pre-cooled working fluid then flows into intercooler  222 , where its temperature is further decreased before entering second airend stage S 2  of coolant-free airend  220 . The working fluid is compressed further, increasing in temperature once again. The compressed working fluid flows into the second evaporator  238  acting as a pre-aftercooler. The organic fluid in second evaporator  236  absorbs the waste heat from the working fluid, evaporating as a result. The pre-cooled working fluid then flows into aftercooler  224 , where its temperature is further decreased prior to exiting the turbocharged fluid compressor system  200  for delivery. As waste heat is produced in relatively equal amounts in first and second airend stages S 1  and S 2 , it is possible to have first evaporator  236  and second evaporator  238  working in parallel, evaporating the organic fluid flowing through the ORC system  202 . 
     Turbocharged fluid compressor system  200  may include a coolant/lubricant circulation system where a coolant/lubricant cools and/or lubricates the working fluid without mixing with the working fluid in neither of the airend stages S 1  and S 2 . The coolant/lubricant may absorb heat from the working fluid as it cools/lubricates the working fluid. In example embodiments, the heat absorbed by the coolant/lubricant may be used to preheat the ORC fluid before the ORC fluid enters the pre-intercooler  208  or the pre-aftercooler  238 . The hot coolant/lubricant may also be circulated to a third evaporator (not shown) that absorbs the excess heat absorbed by the coolant/lubricant before the coolant/lubricant recirculates. 
     In example embodiments, the intercooler  222  and the aftercooler  224  may be reduced in size, as the majority of the excess heat in the working fluid is absorbed by the evaporating organic fluid in first and second evaporators. In example embodiments, the first evaporator  236  and the second evaporator  238  may replace intercooler  222  and aftercooler  224 , respectively. 
     The thermal efficiency of the ORC system varies depending on the chosen organic compound used as the waste heat recovery fluid, as different organic compounds have different boiling point temperatures. Examples of organic compounds include but are not limited to HDR-14, isobutane, isopentane, R245fa, SES36, R227ea, among others. For example, in turbocharged fluid compressor system  200 , the working fluid compressed by coolant-free airend  220  has a higher discharge temperature than the discharge temperature of the working fluid compressed by contact-cooled airend  120  in turbocharged fluid compressor system  100 . The organic fluid used in turbocharged fluid compressor system  100  may be an organic compound (e.g., HDR-14) suitable for evaporating at a lower temperature than the evaporating temperature of the organic compound (e.g., isobutane) used in turbocharged fluid compression system  200 . It should be understood that the selection of the waste heat recovery fluid may change based on specific configurations, parameters and requirements of each application. 
     The turbocharged fluid compressor system may be retrofitted into existing compression systems. The application of the turbocharged fluid compressor system is not limited to fluid compression systems, as any equipment having a compression application with waste heat available from within or outside the compression system may benefit from the increased efficiency as a result of the turbocharged compressor system. Other applications include but are not limited to HVAC systems, refrigeration systems, gas turbines, etc. 
     While the subject matter has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the subject matters are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the subject matter, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     Although the subject matter has been described in language specific to structural features and/or process operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.