Patent Abstract:
An air compressor system includes a compressor having an intake end and a discharge end, the compressor operable to draw in atmospheric air at the intake end and to discharge a flow of compressed air from the discharge end, the flow of compressed air including a flow of entrained water vapor and lubricant. The system further includes a separator operable to remove a portion of the entrained water vapor and lubricant from the flow of compressed air, the separator discharging a flow of dry compressed air and a flow of effluent which includes the separated water vapor and lubricant. Further, the system includes an electric heater configured to receive the removed effluent from the separator at an entrance to the electric heater and to vaporize the removed effluent.

Full Description:
BACKGROUND 
       [0001]    The present invention relates to a system for vaporizing effluent discharged from a compressor. 
         [0002]    Compressors are used to compress gas for use in various processes. Some compressors use oil as a lubricant and a coolant during compressor operation. The oil lubricates and seals the compressor and carries away excess heat during use. A small portion of the oil is typically discharged with the flow of compressed gas that is discharged from the compressor. In compressor systems that compress air, the air is typically drawn from the atmosphere and therefore contains at least some water vapor. During the compression process, some of this water vapor can condense out of the compressed air and be carried out of the air compressor with the small quantity of oil, especially in applications where the compressed service air is cooled prior to discharge. 
       SUMMARY 
       [0003]    In one construction of an air compressor system, the system includes a compressor having an intake end and a discharge end, the compressor operable to draw in atmospheric air at the intake end and to discharge a flow of compressed air from the discharge end, the flow of compressed air including a flow of entrained water vapor and lubricant. Additionally, the system includes a separator operable to remove a portion of the entrained water vapor and lubricant from the flow of compressed air, with the separator discharging a flow of dry compressed air and a flow of effluent which includes the separated water vapor and lubricant. Further, the system includes an electric heater configured to receive the removed effluent from the separator at an entrance to the electric heater and to vaporize the removed effluent. 
         [0004]    In another construction of an air compressor system, the system includes an oil-flooded compressor having an intake end for the intake of air and a discharge end from which a compressed air stream with entrained effluent exits the compressor. Additionally, the system includes an electric motor coupled to the compressor and operable to drive the compressor. Further, the system includes an after cooler coupled to the discharge end of the compressor and operable to cool the compressed air stream and effluent to condense a portion of the effluent and a moisture separator coupled to a discharge end of the after cooler and configured to remove a portion of the condensed entrained effluent from the compressed air stream. Even further, the system includes an electric pass-through heater configured to receive the removed effluent from the moisture separator, and configured to vaporize the removed effluent. 
         [0005]    Another construction provides a method of operating an electrically-powered air compressor. The method includes powering an oil-flooded compressor with an electric motor, the compressor producing a flow of compressed air and effluent, the effluent including compressed water vapor and oil, cooling the flow of compressed air and effluent to condense a portion of the effluent, and separating the flow of compressed air and effluent into a flow of dry compressed air and a flow of condensed effluent. The method further includes heating the flow of condensed effluent in an electrically-powered heater to vaporize the effluent and discharging the vaporized effluent to the atmosphere. 
         [0006]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic illustration of a condensate vaporization system. 
           [0008]      FIG. 2  is a flow chart illustrating a method of operating the condensate vaporization system of  FIG. 1 . 
       
    
    
       [0009]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
       DETAILED DESCRIPTION 
       [0010]      FIG. 1  schematically illustrates a compressor system  5 , including a condensate vaporization system  10  and a particulate removal system  15 , for producing a compressed gas stream and for removal of entrained effluent from the compressed gas stream to produce a stream of clean compressed gas that contains minimal moisture and lubricant. Effluent is generally defined as a mixture of water and oil (i.e., primarily water with a small amount of entrained lubricant), and is essentially the liquid medium that resides downstream of an aftercooler in a compressor system. Before proceeding further, it should be noted that the present system can be used to compress many different gases. However, for clarity, the system will be described herein as it applies to an air compressor system. The compressor system  5  includes a compressor  14 , a motor  18 , an aftercooler heat exchanger  22 , a controller  50 , a compressor temperature sensor  58 , a compressor pressure sensor  62 , an ambient air temperature sensor  66 , and an ambient air relative humidity sensor  68 . The particulate removal system  15  of the compressor system  5  includes a separator  26  and first and second filters  30 ,  34 . The condensate vaporization system  10  of the compressor system  5  includes an electric heater  38 , and a heater temperature sensor  54 . 
         [0011]    In the illustrated construction, the compressor  14  is an oil flooded screw compressor. The compressor  14  includes a compressor air inlet  70  open to the atmosphere. The compressor  14  further includes a compressor discharge end  78 . The motor  18  couples to the compressor  14  and is operable to drive the compressor  14 . In the illustrated construction, the motor  18  is an electric motor that electrically couples to a power source (not shown). In other constructions the motor  18  can be another prime mover operable to drive the compressor  14 . 
         [0012]    The aftercooler  22  includes an aftercooler inlet  82  that receives a flow of compressed air from the compressor  14  and an aftercooler outlet  86  where the cooled compressed air is discharged. Additionally, the aftercooler  22  fluidly couples to a cooling source with a cooling fluid (e.g., air, coolant, water) that passes through the aftercooler  22  such that the cooling fluid thermally communicates with compressed air that is within the aftercooler  22  between the aftercooler inlet  82  and the aftercooler outlet  86 . 
         [0013]    The aftercooler  22  discharges the cooled flow of compressed air to the separator  26  (e.g., a moisture separator or water separator). The separator  26  includes a separator inlet  90 , a first separator outlet  94 , and a second separator outlet  98 . The second separator outlet  98  couples to a discharge line  110 . 
         [0014]    Downstream of the aftercooler  22  are the first and second filters  30 ,  34 . In the illustrated construction, the first and second filters  30 ,  34  are coalescing filters. In other constructions, other types of filters can be used to remove excess liquid from the compressed air. Further, in some constructions more than two filters, or fewer filters can be utilized, or no filters may be utilized. 
         [0015]    Each filter  30 ,  34  has a filter inlet, an air outlet, and a condensed effluent outlet. The air outlet of the first filter  30  fluidly couples to the second filter  34 . The air outlet of the second filter  34  is connected to other downstream components that ultimately lead to a point of use. For example, a storage tank or large manifold could be connected to the filter  34  to hold a quantity of compressed air for use as may be required. The condensed effluent outlets of the first and second filters  30 ,  34  couple to the discharge line  110 . 
         [0016]    The discharge line  110  includes an orifice  114  which is arranged such that all condensed effluent flowing through the discharge line  110  passes through the orifice  114 . The discharge line  110  fluidly couples the separator  26  and the first and second filters  30 ,  34  to the electric heater  38 . The electric heater  38  (e.g., an electric pass-through heater or tankless water heater) includes a heater inlet  126  and a heater outlet  130 . Further, the electric heater  38  electrically couples to the power source (not shown). In the illustrated construction, the heater outlet  130  is open to the atmosphere. 
         [0017]    The controller  50  is preferably a microprocessor-based controller that electrically couples to the compressor  14  and the electric heater  38  to control various operational parameters of both the compressor  14  and the electric heater  38 . Further, the controller  50  electrically couples to the compressor temperature sensor  58 , the compressor pressure sensor  62 , the ambient air temperature sensor  66 , the ambient air relative humidity sensor  68 , and the heater temperature sensor  54 . 
         [0018]    The compressor temperature sensor  58  and compressor pressure sensor  62  couple to the compressor  14 . For example, the sensors  58 ,  62  may be disposed in a compressor discharge line or downstream of the compressor  14  to directly measure the temperature and pressure of the compressed air exiting the compressor  14 . The sensors  58 ,  62  generate temperature and pressure signals indicative of the measured temperature and pressure of the compressed air and transmit the temperature and pressure signals to the controller  50 . The ambient air temperature sensor  66  and the ambient air relative humidity sensor  68  couple to the compressor  14  near the compressor air inlet  70 . The sensors  66 ,  68  generate temperature and relative humidity signals indicative of the measured temperature and relative humidity of the ambient air entering the compressor  14  and transmit the temperature and relative humidity signals to the controller  50 . Based on the signals from the sensors  58 ,  62 ,  66 ,  68 , the controller is configured to utilize a predictive algorithm to “ready” (e.g., preheat or otherwise adjust the temperature and/or energy flow in anticipation of a change in conditions) the electric heater  38  and prepare the electric heater  38  to vaporize effluent. The heater temperature sensor  54  couples to the electric heater  38 . For example, the heater temperature sensor  54  may be disposed inside a discharge line of the electric heater  38  to directly measure the temperature of the vaporized effluent exiting the electric heater  38 . The heater temperature sensor  54  generates a temperature signal indicative of a measured temperature of the vaporized effluent and transmits the temperature signal to the controller  50 . 
         [0019]    The signals from the compressor pressure sensor  62 , the compressor temperature sensor  58 , the ambient air temperature sensor  66 , the ambient air relative humidity sensor  68 , and the heater temperature sensor  54  are used in determining how the compressor  14  and/or electric heater  38  are operated. In other constructions, the operation of additional components can be determined by the signals from the sensors  54 ,  58 ,  62 ,  66 ,  68  (e.g., the motor  18  or the power source). Further, in alternative constructions, additional sensors  54 ,  58 ,  62 ,  66 ,  68 may be utilized in similar positions as those described above, or in additional positions in and around the compressor  14  and the electric heater  38 . In preferred constructions, the sensors  54 ,  58 ,  62 ,  66 , and  68  transmit analog or digital signals to the controller  50 . 
         [0020]    The flowchart of  FIG. 2  illustrates operation of the condensate vaporization system  10  starting with block  200 . The power source provides power to the motor  18 , which drives the compressor  14 . The compressor  14  intakes air through the compressor air inlet  70  from the surrounding atmosphere. Further, in the illustrated embodiment, a pump (not shown) provides oil to the compressor  14 . The compressor  14  compresses the air, and directs the air outward through the compressor discharge end  78 . During the compression process, oil is used to seal the compressor  14  and to cool the compressor  14 . As air is discharged, a small portion of oil is entrained with the air. In addition, the compression process can cause some moisture to condense within the air stream. The compressed air directed outward from the compressor  14  includes this water vapor, oil vapor, and oil additive vapors in the form of an entrained effluent. 
         [0021]    The aftercooler  22  receives the compressed air at the aftercooler inlet  82  and cools the air (see block  204 ) by allowing thermal communication between the compressed air and the cooling fluid. Cooling the compressed air condenses a first portion of the entrained effluent. The aftercooler  22  then directs the compressed air and the first portion of condensed effluent through the aftercooler outlet  86  to the separator inlet  90 . 
         [0022]    The separator  26  separates the first portion of the condensed effluent from the compressed air and directs the first portion through the second separator outlet  98  to the discharge line  110  (see block  208 ). The separator  26  then directs the compressed air through the first separator outlet  94  to the first and second filters  30 ,  34 . 
         [0023]    In the illustrated construction, the first filter  30  separates a second portion of condensed effluent from the compressed air. The second portion of condensed effluent passes to the discharge line  110 . The compressed air passes to the second filter  34 . The second filter  34  separates a third portion of condensed effluent from the compressed air. The third portion of condensed effluent passes to the discharge line  110 . The compressed air exits out of the particulate removal system  15  in the form of dry compressed air. In preferred constructions, the air is heated after exiting the filters to assure that the air temperature is well above the air&#39;s dew point temperature. Generally, dry compressed air has a dew point at least 20 degrees below the discharge temperature of the air. The first, second, and third portions of condensed effluent pass through the discharge line  110  and through the orifice  114 . The condensed effluent (e.g., the first, second, and third portions) then pass through the heater inlet  126  to the electric heater  38 . The orifice  114 , in some constructions, is selected specifically to control the amount of compressed air lost and to allow the condensate to escape at the rate accumulated. In other embodiments, a check valve or pressure reducing valve may be used to decrease the pressure of the condensed effluent. The power source powers the electric heater  38  to heat the condensed effluent in the electric heater  38 . The electric heater  38  heats the condensed effluent to a temperature at which water, as well as some additional effluent constituents, will vaporize. A temperature control can also be employed to limit the temperature and to control vaporizing of the effluent constituents as desired (see block  212 ). In other constructions, additional electric heaters may be included to provide additional heating to the condensed effluent. Further, the additional heaters may be arranged with the electric heater  38 , downstream of the discharge line  110 , either in series or in parallel. The vaporized effluent then passes through the heater outlet  130  to the atmosphere (see block  216 ). 
         [0024]    Referring again to  FIG. 1 , the controller  50  controls the amount of electricity provided to the electric heater  38  by the power source. The compressor temperature sensor  58  detects the temperature of the compressor  14  and sends compressor temperature measurements to the controller  50 . The compressor pressure sensor  62  detects the pressure in the compressor  14  and sends compressor pressure measurements to the controller  50 . The ambient air temperature sensor  66  detects the temperature of the ambient air entering the compressor  14  and sends the ambient air temperature measurements to the controller  50 . The ambient air relative humidity sensor  68  detects the relative humidity of the ambient air entering the compressor  14  and sends the ambient air relative humidity measurements to the controller  50 . The heater temperature sensor  54  detects the temperature of the electric heater  38  and sends heater temperature measurements to the controller  50 . 
         [0025]    The controller  50  receives the compressor temperature measurements, the compressor pressure measurements, the ambient air temperature measurements, the ambient air relative humidity measurements, and the heater temperature measurements. Based on one or more of these measurements, the controller  50  determines and controls the amount of electricity that is provided to the electric heater  38  to ensure that the condensed effluent within the electric heater  38  is fully vaporized. Further, based on the signals from the sensors  58 ,  62 ,  66 ,  68 , the controller  50  may utilize a predictive algorithm to “ready” (e.g., preheat or otherwise adjust the temperature and/or energy flow in anticipation of a change in conditions) the electric heater  38  and prepare the electric heater  38  to fully vaporize the condensed effluent for a given demand (i.e., kilowatt input or heat load). Further, the ambient temperature and relative humidity measurements allow the controller  50  to determine the total amount of water coming into the system to better estimate the amount of heat required to fully vaporize the effluent. 
         [0026]    Various features and advantages of the invention are set forth in the following claims.

Technology Classification (CPC): 5