Abstract:
A method of treating a contaminated refrigeration fluid including the steps of transferring, separating, returning, moving and removing. The transferring step includes the transferring of a portion of the contaminated refrigeration fluid from a refrigeration system to a first tank. The separating step includes the separating of refrigerant from the portion of the contaminated refrigeration fluid resulting in the refrigerant and a refrigerant depleted portion. The returning step includes the returning of the refrigerant to the refrigeration system. The moving step includes the moving of the refrigerant depleted portion to a second tank. The removing step includes the removing of oil from the refrigerant depleted portion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a division of U.S. patent application Ser. No. 11/494,920, entitled “AMMONIA RECYCLING STILL FOR A REFRIGERATION SYSTEM AND METHOD THERFOR”, filed Jul. 28, 2006, which is incorporated herein by reference. U.S. patent application Ser. No. 11/494,920 is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/704,097, entitled “AMMONIA RECYCLING STILL FOR A REFRIGERATION SYSTEM AND METHOD THEREFOR”, filed Jul. 29, 2005. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an ammonia still apparatus and method for purifying ammonia from contaminated refrigeration fluid. 
         [0004]    2. Description of the Related Art 
         [0005]    In the classic compression type refrigeration system, a refrigerant is alternately compressed and expanded. In a simple closed loop compression type refrigeration system, there is at least a compressor, an evaporator, a throttling or metering device, and a condenser. During one stage of the compression type refrigeration cycle, a low pressure refrigerant vapor enters the compressor. At this point in the cycle, work is required of the compressor in. order to raise the pressure and the boiling point of the refrigerant vapor. In the next phase of the compression type refrigeration cycle, the high pressure, high temperature refrigerant vapor leaving the compressor is transferred through a heat exchanger called a condenser. A second fluid passes through the condenser in order to remove heat from the refrigerant vapor, thereby transforming the refrigerant vapor to a refrigerant liquid. As the refrigerant liquid exits the condenser, it leaves at the same pressure but at a lower temperature than it had upon entering the condenser. 
         [0006]    Next, the refrigerant passes through a throttling device that reduces the pressure, temperature and boiling point of the fluid. In the last step of the typical compression type refrigeration cycle, refrigerant travels through an evaporator to receive heat from some other fluid in communication with the evaporator to achieve the desired cooling effect of this other fluid. Such a closed loop compression refrigeration cycle is duplicated in order to repetitively remove heat from a body of fluid in communication with the evaporator. 
         [0007]    Commercial and industrial refrigeration systems typically use anhydrous ammonia. Anhydrous ammonia is the liquid form of pure ammonia gas and is technically water-free. Most refrigeration experts consider industrial grade anhydrous ammonia to be the most economical and efficient heat transfer medium for industrial refrigeration processes. 
         [0008]    Water, unfortunately, finds its way into the refrigeration system, and over time, accumulates to a level of concern. Ammonia readily associates with water to form ammonium hydroxide, an inferior refrigerant that reduces the efficiency of the refrigeration system. The reduced efficiency increases the use of energy consumed in the system, thus increasing the cost of operation and also accelerates wear and tear on equipment causing shorter mean time to failure. 
         [0009]    In an industrial refrigeration system, compressors, piping, and vessels containing anhydrous ammonia are prevalent throughout the refrigeration plant. Such a refrigeration system generally has lubricating oils inserted into the compressor for lubrication. Invariably, some of the oil or other lubricant migrates throughout the system, mixing with the anhydrous ammonia. Since the oil serves as an insulator or retardant to heat transfer, a high prevalence of waste oil in a refrigeration system compromises the efficiency of the refrigeration process. In addition, chemical reactions can occur between the oil, ammonia and/or water to produce additional waste products, such as sludge and acids. The addition of oil and water to ammonia can also provide a rich medium for microbiological growth which can produce slime and acids to further degrade the efficiency of operation as well as physically damage the system. 
         [0010]    In order to prevent deterioration of the refrigeration efficiency as well as the physical parts of the system, accumulations of waste lubricating oil and water need to be purged from the system. Most commercial and industrial refrigeration units include one or more ports located at a lower level in the piping system and arranged such that lubricating oil will accumulate there to be drained from the pipes for collection and/or discarding. Unfortunately, the ammonia is wasted in these systems. 
         [0011]    Therefore a need exists to purify and recycle ammonia in a refrigeration system from waste fluid having waste oil and water contaminants while preventing the undesirable side effects associated with draining waste fluid. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention, in one form, consists of a method of treating a contaminated refrigeration fluid including the steps of transferring, separating, returning, moving and removing. The transferring step includes the transferring of a portion of the contaminated refrigeration fluid from a refrigeration system to a first tank. The separating step includes the separating of refrigerant from the portion of the contaminated refrigeration fluid resulting in the refrigerant and a refrigerant depleted portion. The returning step includes the returning of the refrigerant to the refrigeration system. The moving step includes the moving of the refrigerant depleted portion to a second tank. The removing step includes the removing of oil from the refrigerant depleted portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0014]      FIG. 1  is front plan view of the ammonia still apparatus of the invention with the electrical lines removed for easier viewing; 
           [0015]      FIG. 2  is a side plan view of the ammonia still apparatus of the invention with the electrical lines removed for easier viewing; 
           [0016]      FIG. 3  is a top plan view of the ammonia still apparatus of the invention with the ammonia discharge line removed; and 
           [0017]      FIG. 4  is a side plan view of the ammonia still apparatus of the invention with additional valves for access to the apparatus and electrical lines drawn schematically. 
       
    
    
       [0018]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification(s) set out herein illustrate(s) (one) embodiment(s) of the invention (, in one form,) and such exemplification(s) (is)(are) not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Turning to the Figures, where like reference numerals refer to like structures, an ammonia still apparatus  10  of the invention is used to purify and recycle anhydrous ammonia from contaminated ammonia refrigerant fluid. The ammonia still apparatus  10  is in fluid communication with an ammonia refrigeration system  12  and can be used manually with or without an electronic controller, such as a programmable logic controller (PLC)  14  to control the operations of the ammonia still apparatus  10 . The PLC  14  is communication with the ammonia still apparatus  10  and is preferably part of the ammonia still apparatus  10 , although the PLC  14  can be installed in another location and wired to the ammonia still apparatus  10 . 
         [0020]    During manual operation with the PLC  14 , a solenoid energizes to open a valve immediately in response to a pushbutton input from the control panel  16  of the PLC  14 , once a particular function is selected. In this disclosure, the term “solenoid” is used to refer to a solenoid or the combination of the solenoid and the valve the solenoid controls. Upon release of the pushbuttons, the solenoid de-energizes and the valve closes. 
         [0021]    The PLC  14  can be programmed to control the solenoids in the ammonia still apparatus  10 . The PLC  14 , for example, can be programmed to have the following functions in response to the input from particular programmed function keys. For example, F 1  is programmed to energize a suction solenoid  50 . F 2  is programmed to energize the liquid solenoid  22 . F 3  is programmed to energize a hot gas solenoid  60 . F 4  is programmed to energize a discharge solenoid  72 . F 5  is programmed to energize a water dump solenoid  88 . 
         [0022]    The solenoids open immediately in response to switching a selector switch  18  on the front of the control panel  16  from manual operation to automatic operation. Once in automatic operation, the suction solenoid  50  and liquid solenoid  22  energize and their valves open. Contaminated ammonia refrigerant fluid flows from the ammonia refrigeration system  12  through a liquid inlet  20  into a tank  26 . The liquid inlet  20  has a liquid solenoid  22 , preferably with a strainer, that controls the flow of contaminated fluid into the ammonia still apparatus  10 . 
         [0023]    The tank  26  has an upper tank  28 , such as a vertical pipe, in fluid communication with the liquid inlet  20 , an ammonia line  40  and a lower tank  30 , such as a horizontal pipe. The upper tank  28  can have a cap  32  covering the top with an upper opening  34  for receiving a plug  36  or a safety relief valve. At the bottom of the lower tank  30  is a tank outlet  38 . If desired, the tank  26  can be insulated. 
         [0024]    Contaminated ammonia refrigerant fluid flowing into the tank  26  can be measured with an upper liquid sensor  42 , such as a float switch  44 . The float switch  44  is in communication with the PLC  14  and in fluid communication with the tank  26 . The contaminated fluid level in the tank  26  rises until reaching a set maximum level. Then the float switch  44  signals to the PLC  14  that the contaminated fluid is at the maximum level. The PLC  14  de-energizes the liquid solenoid  22  and closes its valve to stop the flow of contaminated fluid into the tank  26 . The suction solenoid  50  remains energized and open. 
         [0025]    The float switch  44  has an upper float line  46  and a lower float line  47 . The upper float line  46  is in fluid communication with the upper tank  28 . The lower float line  47  is in fluid communication with the tank outlet  38 : When the contaminated fluid level in the tank  26  rises, a float rod in the float switch  44  also rises until reaching the maximum fluid level. At the maximum fluid level, the float switch  44  signals the PLC  14  and switches off the flow of contaminated fluid into the tank  26 . 
         [0026]    As soon as the liquid solenoid  22  de-energizes and closes, the PLC  14  activates a heat exchanger  48  in fluid communication with the tank  26 . The heat exchanger  48  has a heat exchanger fluid inlet  54  and a waste fluid outlet  56  at the opposite end for discharging waste fluid, such as water and oil. The heat exchanger  48  heats the contaminated fluid from the tank  26  to boil off anhydrous ammonia. The heat exchanger  48  should maintain a temperature of about 60° F., but can be set at a temperature range of about 0° F. to about 100° F., with a preferable range of about 60° F. to about 65° F. Once reaching the boiling point of ammonia, anhydrous ammonia boils and separates from the heated contaminated fluid. The anhydrous ammonia passes upward through the contaminated fluid and back into the tank  26 . The anhydrous ammonia discharges from the tank  26  through the ammonia discharge line  40  and back into the refrigeration system  12  where it is reused. The ammonia discharge line  40  has the suction solenoid valve  50  which opens to allow the anhydrous ammonia out of the ammonia still apparatus  10 . An ammonia regulator  52  in the ammonia discharge line  40  can control the pressure of the anhydrous ammonia. 
         [0027]    The heat exchanger  48  is preferably a fluid heat exchanger  58  using hot gas, such as ammonia, available from the plant to heat the contaminated fluid. The PLC  14  energizes a hot gas solenoid  60  and its valve opens to allow hot gas to flow through the hot gas inlet  62  into the heat exchanger  58 . A hot gas regulator  64  can control the pressure in the hot gas inlet  62 , typically between about 100 psi to about 120 psi. 
         [0028]    The hot gas heats the contaminated fluid, and in doing so, cools and can condense. The condensate flows out of the heat exchanger  58  though a discharge outlet  66 . The discharge outlet  66  can have a drain trap  68  leading to a drain  70  in fluid communication with the plant. A discharge solenoid  72  communicates with the PLC  14 , which controls the energizing of the discharge solenoid  72  and the opening of its valve to return liquid condensate to the plant. 
         [0029]    Upper and lower temperature sensors  74 ,  76  are located at opposite ends of the heat exchanger  54 . The temperature sensors  74 ,  76  measure the temperature of the fluid at both ends of the heat exchanger  54  and communicate the measured temperatures to the PLC  14 . The upper temperature sensor  74  measures the upper temperature of the contaminated fluid between the tank  26  and the heat exchanger  54 , such as at a first fitting  78  connecting the tank outlet  38 , a heat exchanger fluid inlet  54  and the lower float line  47 . The lower temperature sensor  76  measures the lower temperature of the waste fluid discharged from the heat exchanger  54 , preferably at a second fitting  80  connecting the waste fluid outlet  56  with a water/oil discharge line  82  and a lower liquid sensor  84 , such as a liquid switch  81 . 
         [0030]    If the lower temperature sensor  76  and the upper temperature sensor  74  signal the PLC  14  that the temperatures of the contaminated fluid and the waste fluid have reached the temperature set point (which can be shown on the PLC  14  display screen) but the tank fluid level in the tank  26  has not reached the set maximum tank fluid level measured by the upper liquid sensor  42 , the system repeats the process from the beginning. Alternatively, if the upper and lower temperature sensors  74 ,  76  are not equal and the tank fluid level in the tank  26  has not reached the set maximum level, the cycle restarts. To restart the cycle, the hot gas solenoid  60  and the discharge solenoid  72  de-energize and close while the liquid solenoid  22  energizes and opens again until the tank fluid level in the tank  26  reaches the maximum level. 
         [0031]    The system repeats the cycle until the upper and lower temperature sensors  74 ,  76  signal the PLC  14  that the upper and lower temperatures are equal. Once the upper and lower temperatures are equal and the tank fluid level in the tank  26  reaches the upper level switch  42 , the ammonia still apparatus  10  is ready to discharge the waste fluid which has been collecting. 
         [0032]    At this point, the PLC  14  signals the hot gas solenoid  60 , the suction solenoid  50  and the discharge solenoid  72  to de-energize and close. The water fill solenoid  86  for an oil skimmer tank  92  now energizes and opens its valve to send fresh water into the oil skimmer tank  92 . After a period of time, such as five minutes, the waste dump solenoid  88  energizes and opens its valve to dump the waste fluid into the oil skimmer tank  92  and the suction solenoid  50  de-energizes and closes. The water fill solenoid  86  remains energized during this time. A flow meter  90  measures the flow of the waste fluid from the ammonia still apparatus  10  and an associated throttling valve can regulate the rate of flow. 
         [0033]    When the lower liquid sensor  84  for the water dump reaches its set lower waste fluid level point, the lower liquid sensor  84  sends a signal back to the PLC  14 . The PLC  14  signals the water dump solenoid  88  and water fill solenoid  86  to de-energize and close. The cycle begins again by energizing and opening the suction and liquid solenoids  50 ,  22 . 
         [0034]    In the oil skimmer tank  92 , the oil is allowed to separate from the water. Fresh water can flow into the oil skimmer tank  92  to help dilute any remaining ammonia by absorbing it into a larger mass of water and preventing undesirable odor in the installed location. The separated oil is drawn off into an oil receiver  95 , such as a bucket. An oil flow meter  94  in fluid communication with the oil line  98  can measure the amount of oil collected and send the measured amount to the PLC  14 . An oil level sensor switch  96  in communication with the PLC  14  could also be used to turn off the ammonia still apparatus  10  if the oil receiver  94  is filled. The separated oil can then be collected and disposed separately from the water. 
         [0035]    The number of gallons of water dumped from the system is displayed on the display screen of the PLC  14 . Alternatively, the number of gallons dumped can be sent to a networked computer or printer, as well as other data which can be collected, such as temperature and pressure. 
         [0036]    The PLC can be programmed from the control panel in the program mode or run in a previously programmed mode. The PLC can also be part of a computer network and can be remotely programmed from the network. The program mode allows maximum flexibility to alter the parameters of the system to match the conditions of the plant and fluid. The PLC can also be programmed to draw fluid from different points in the refrigeration system. The run mode allows the continuous running of the ammonia still apparatus of the invention without requiring an operator to monitor and dump out the system. This also allows the ammonia still apparatus to run while providing shut-offs and safeguards to the system. 
         [0037]    The display screen can constantly show the upper and lower sensor temperatures, the number of gallons of water dumped from the system and the temperature set point. The temperature set point is the same for both the upper and lower sensors. Once the system is in the run mode, the display screen can show the current conditions of the system, such as the upper and lower temperatures, the temperature set point and the gallons of water produced. 
         [0038]    Regulators can be used in the hot gas and ammonia lines to control pressure if desired. Pressure sensors can also be used to send feed back to the PLC  14  and monitor the pressure in the system. Additional valves  100 ,  101 ,  102  can be used in the lines for additional access to the ammonia still apparatus for safety. 
         [0039]    The ammonia still apparatus of the invention allows the ammonia refrigerant to be purified over time for greater efficiency in the operation of the refrigeration system. As a result, the refrigeration system requires fewer compressors, smaller equipment and higher pressures to maintain adequate temperatures in the facility. This greatly decreases energy costs and other expenses, such as system cleaning and pipe replacement, and reduces wear and tear on the equipment. 
         [0040]    While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.