Abstract:
A liquid ring pump includes a housing defining an interior working space sized to receive a quantity of gas and a quantity of sealing liquid, a pump head coupled to the housing and defining an inlet channel, an outlet space, and a cone seal area, and an intake valve movable between an opened position and a closed position to control the quantity of a gas entering the inlet channel. A reservoir contains a quantity of sealing liquid, a pump discharge path provides fluid communication between the outlet space and the reservoir, and a first flow member includes a first valve coupled to the reservoir and the inlet channel to provide fluid communication therebetween. A second flow member includes a second valve coupled to the reservoir and the cone seal area to provide fluid communication therebetween and a rotor is supported for rotation by a shaft, the rotor disposed at least partially within the working space, the pump operable in a start-up mode to draw sealing liquid into the working space via only the first flow member and during normal operation to draw sealing liquid into the working space via only the second flow member.

Description:
BACKGROUND 
       [0001]    The disclosure concerns compressor type liquid ring pumps having a sealing liquid introduction path. 
         [0002]    Liquid ring pumps and their operation are well known. In general liquid ring pumps utilize a liquid ring which, during operation, delimits a pumping chamber. The ring is eccentric to an axis of a shaft. The shaft rotates a rotor. A radial inward surface of the liquid ring is radially spaced from the shaft at an intake zone to allow buckets formed by adjacent blades of the rotor to fill with gas entering the pump&#39;s working chamber through an inlet port. The inlet port is downstream of a pump head inlet. The buckets fill with gas as they sweep past the inlet port. The inlet port can be in a member extending into an orifice formed by the rotor blades or it can be in a port plate. 
         [0003]    The radial inward surface of the liquid ring in a compression zone is oriented relative to the shaft to compress the gas in the buckets and force the gas through an outlet port which leads into an outlet of the pump. The ring compresses the gas in the buckets because of its eccentric orientation relative to the shaft. The orientation means the radially inward surface of the liquid ring has a much closer approach to the axis of the shaft in the radial direction along the compression zone as compared to its approach along the intake zone. U.S. Pat. No. 4,498,844, Bissell provides a comprehensive description of how a liquid ring pump operates and some of its basic structure. 
         [0004]    Liquid ring pumps include a category of pumps known as compressor type liquid ring pumps. These pumps include a sealing liquid flow path along which sealing liquid flows into the head and working chamber of the pump. The sealing liquid, in part, seals interstices to prevent leakage of gas through the interstices. For instance, the sealing liquid is needed to seal the interstices between the shaft and a conical port member which has the inlet port opening into the working chamber. The sealing liquid flow path is oriented relative to the working chamber and other features and areas of the pump to ensure the sealing liquid enters the working chamber outside of the inlet channel in the pump head which opens into the inlet port. The flow path is also oriented to ensure the sealing liquid enters the working chamber outside of the void space formed by the buckets and the liquid ring in the intake zone of the working chamber. Keeping the sealing liquid from entering these areas and outside of these areas prevents the sealing liquid, an incompressible fluid, from occupying space in these areas and displacing intake gas. Thus the supply of the sealing liquid outside of these areas ensures the sealing liquid does not displace void spaces fillable by the intake gas. 
         [0005]    In a known system, during startup, an entry area from which sealing liquid travels to enter into interstices to be sealed by the sealing liquid is at a pressure near to that of the sealing liquid along a flow path which is distal and upstream of the entry area. The entry area can be at the cone seal area. To create a sufficient pressure difference, to flow sealing liquid into the entry area along a portion of the sealing liquid flow path proximate the entry area, an extra pump in fluid connection with the flow path and upstream of the entry area is used. The pump puts the sealing liquid upstream of the entry at a sufficiently higher pressure at start-up than the pressure at the entry. The higher pressure forces the sealing liquid into the interstices. After start-up, the pressure at the pump discharge increases. The flow path, distal of the entry area is in flow connection with the pump discharge and downstream of the pump discharge. Thus the sealing liquid in the portion of the flow path distal to the entry is at the discharge pressure. Therefore, the sealing liquid at discharge pressure forces sealing liquid along the proximate portion of the flow path into the entry area and into the interstices during the running mode. 
       SUMMARY 
       [0006]    One example of the invention is embodied in a compressor type liquid ring pump package. The compressor type liquid ring pump package provides for the flow of the sealing liquid into the interstices to be sealed by the sealing liquid at start-up without an extra pump. The compressor type liquid ring pump package comprises a sealing liquid flow path in fluid connection with a pump discharge outlet of the pump package and downstream of the pump discharge outlet. A portion of the sealing liquid flow path is proximate an entry area. The proximate portion is in fluid connection with the entry area and upstream of the entry area. The entry area can be considered part of the sealing liquid flow path. The entry area preferably comprises a portion of the inlet channel in the pump head of the pump package. The sealing liquid flow path can be called a sealing liquid introduction path. 
         [0007]    During start-up, the pressure Pi at the entry area is sufficiently less than the pressure Pd of the sealing liquid along a portion of the sealing liquid flow path distal the entry area. The distal portion is proximate a sealing liquid supply from which the sealing liquid flow path receives sealing liquid. The distal portion of the sealing liquid flow path is upstream of the proximate portion. The sufficient pressure difference exists during start-up without the extra pump and is created by operation of the pump rotor without the extra pump. The pressure at the entry area is near or at zero during startup. The sufficient pressure difference means that a sufficient volume of the sealing liquid upstream of the entry area will flow along the flow path into the entry area during start-up. The sufficient volume is a volume which fills the interstices and otherwise allows for proper operation of the pump. Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
         [0008]    In one construction, a method of starting a liquid ring pump arranged to compress a gas includes providing a quantity of sealing liquid in a reservoir, the reservoir and a pump head inlet channel being at the same pressure prior to starting the compressor. The method also includes providing a first fluid connection between the pump head inlet channel and the reservoir, moving an intake valve toward a closed positioned at a gas entry opening of the pump head inlet channel to limit the quantity of gas that can pass through the valve to a first quantity, and producing a partial vacuum in the pump head inlet channel by initiating the start sequence for the liquid ring pump. The liquid ring pump is initially operable to pump more than the first quantity of gas. The method further includes drawing fluid from the reservoir via the first fluid connection in response to the pressure differential. 
         [0009]    In another construction, a compressor type liquid ring pump that includes a housing defining an interior working space sized to receive a quantity of gas and a quantity of sealing liquid, a pump head coupled to the housing and defining an inlet channel, an outlet space, and a cone seal area, and an intake valve movable between an opened position and a closed position to control the quantity of a gas entering the inlet channel. A reservoir contains a quantity of sealing liquid, a first flow member includes a first valve coupled to the reservoir and the inlet channel to provide fluid communication therebetween, and a second flow member includes a second valve coupled to the reservoir and the cone seal area to provide fluid communication therebetween. A rotor is supported for rotation by a shaft, the rotor disposed at least partially within the working space and operable to draw in the gas from the inlet channel at an inlet pressure and to discharge the gas to the outlet space at an outlet pressure that is higher than the inlet pressure. During start-up the intake valve is moved toward the closed position, the first valve is opened and the second valve is closed, and during normal operation, the intake valve is moved toward the open position, the first valve is closed and the second valve is opened. 
         [0010]    In still another construction, a compressor type liquid ring pump includes a housing defining an interior working space sized to receive a quantity of gas and a quantity of sealing liquid, a pump head coupled to the housing and defining an inlet channel, an outlet space, and a cone seal area, and an intake valve movable between an opened position and a closed position to control the quantity of a gas entering the inlet channel. A reservoir contains a quantity of sealing liquid, a pump discharge path provides fluid communication between the outlet space and the reservoir, and a first flow member includes a first valve coupled to the reservoir and the inlet channel to provide fluid communication therebetween. A second flow member includes a second valve coupled to the reservoir and the cone seal area to provide fluid communication therebetween and a rotor is supported for rotation by a shaft, the rotor disposed at least partially within the working space, the pump operable in a start-up mode to draw sealing liquid into the working space via only the first flow member and during normal operation to draw sealing liquid into the working space via only the second flow member. 
         [0011]    In still another construction, a method of providing sealing liquid to a liquid ring pump that is operable in a start-up mode and a normal mode includes providing a reservoir containing a quantity of sealing liquid, a pump head inlet channel, and an outlet space each at atmospheric pressure prior to initiating operation in the start-up mode. The method also includes initiating the start-up mode, throttling a flow of gas into the inlet channel to produce a low pressure region therein during start-up mode operation, and drawing sealing liquid into the inlet channel through a first flow path in response to the low pressure region in the inlet channel. The method further includes increasing the pressure within the outlet space and the reservoir in response to operation in start-up mode, reducing the throttling of the flow of gas into the inlet channel to transition to normal mode, closing a valve in the first flow path to prevent the flow of sealing liquid into the inlet channel, and opening a valve in a second flow path to direct sealing liquid into the pump in response to the increased pressure within the reservoir. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic representational section of a liquid ring pump package embodying features of the present invention. 
           [0013]      FIG. 2  is a cut-away side view of a liquid ring pump package embodying features of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    In an example of the present invention, a liquid/gas separator  11  is in fluid connection with and downstream of a pump discharge outlet  13  in a pump head  15  of a compressor type liquid ring pump package  17 . A sealing liquid reservoir  19  is in fluid connection with and downstream of the liquid/gas separator  11 . A sealing liquid flow path  21  is in fluid connection with the sealing liquid reservoir  19 , separator  11 , and pump discharge outlet  13 . The sealing liquid flow path  21  is downstream of each of these items. The term downstream and upstream as used herein is relative to a flow direction. Thus, if A is upstream of B than there is a fluid connection between A and B and the flow direction of the fluid connection is from A to B. 
         [0015]    When the compressor type liquid ring pump package  17  is in operation, the separator  11 , in a discharge flow direction and along a discharge fluid path  22   a  receives a mixture  22   b  of gas and liquid from the pump discharge outlet  13 . The separator  11  separates the liquid from the gas. Along a collecting flow direction and a collecting flow path  24   a,  the separated liquid collects in the reservoir  19 . The reservoir can be called a sealing liquid supply. 
         [0016]    The sealing liquid flow path  21  places the separated liquid in the reservoir  19  and any outside liquid added to the reservoir in fluid connection with an entry area  26 . A portion  21   a  of the sealing liquid flow path  21  is proximate the entry area  24  and in fluid connection with the entry area  26 . The entry area is downstream of the proximate portion  21   a  of the sealing liquid flow path  21 . The proximate portion  21   a  is in fluid connection with the reservoir  19  but is closer to the entry area  26  than it is to the reservoir  19  and also to a structure  27  connecting the reservoir  19  and the sealing liquid path  21 . The distance is measured along the sealing liquid flow path  21 . A portion of the sealing liquid flow path  21   b  is distal the entry area  26  compared to the proximate portion  21   a.  The distal portion is upstream of the proximate portion and in fluid connection therewith. The structure  27  connects the distal portion  21   b  to the reservoir  19 . The distal portion  21   b  is closer to the reservoir  19 , measured along the sealing liquid flow path, than the proximate portion  21   a.  The distal portion  21   b  connects the proximate portion  21   a  to the sealing liquid supply. 
         [0017]    The entry area  26  can be considered a portion of the sealing liquid flow path  21 . The entry area  26  preferably comprises a space. The space is preferably in a portion of the pump head  15 . The space is preferably downstream of a gas entry  29  opening into an inlet channel  31  in the pump head  15  and upstream of an inlet port  33  opening into a working chamber  36  of the pump package  17 . The gas entry  29 , inlet channel  31 , and inlet port  33  are in fluid connection with each other. The gas travels in a flow direction along a gas flow path  35   a  from the gas entry  29 , into the inlet channel  31  and from the inlet channel through the inlet port  33  into the working chamber  36 . The inlet port  33  is downstream of the inlet channel  31  in the pump head  15 . The space of the entry area  26  is in fluid connection with the gas entry  29 , inlet channel  31 , and inlet port  33 . The space of the entry  26  is preferably at least in fluid connection with the inlet channel  31  and preferably comprises at least part of the inlet channel  31 . The inlet channel preferably comprises at least a portion of the space of the entry area  26 . A portion of the space of the entry area  26  can comprise an opening through an external surface of the pump head. The opening through the external surface is other than the gas entry  29  opening into the inlet channel  31  in the pump head  15 . The inlet port  33  is in a cone  51 . The cone  51  is a cone port having inlet port  33 . 
         [0018]    Alternatively the space of the entry area  26  can comprise the gas entry opening  29  which opens into the inlet channel  31  or the space of the entry area  26  can comprise an exit of the inlet channel. The space of the entry area  26  can more broadly comprise any space through which the sealing liquid passes before it enters interstices  37  in the working chamber  36  and surrounding areas to be sealed by the sealing liquid so long as the space of the entry area  26  is an area where the pressure Pi at this space is sufficiently less than the pressure Pd of the sealing liquid along the distal portion  21   b  of the flow path at and during startup to allow a sufficient volume of sealing liquid to flow into the entry area to effectively seal the interstices and otherwise properly operate the pump. It is believed an appropriate pressure differential is approximately from 2 psi to 5 psi. The space of the entry area  26  is preferably a void space. The sufficient pressure difference of approximately from 2 psi to 5 psi occurs without the aid of an extra pump at startup. The pressure difference occurs as a result of the orientation of the entry area and rotation of the rotor  39  which produces a gas suction, zero pressure, at the gas entry  29  and inlet channel  31  and a gas discharge, positive pressure, at the pump discharge outlet  13 . The orientation includes the position of the entry area relative to other features of the pump package. The startup mode of operation can be considered to commence when the rotor shaft  41  of the liquid ring pump package  17  first begins to rotate until the rotor reaches its operating speed or rated speed or desired speed or the pressure or flow of the gas at the discharge outlet  13  is at its rated, desired or operating pressure or flow. At this speed, pressure or flow the pump package is in the running mode of operation. 
         [0019]    The volume of sealing liquid passing along the entry area  26  during startup compared to the work done by the volume of gas entering the gas entry  29  during startup, the work done approximated by power consumed, should not exceed a ratio, sealing liquid to power consumed, of more than 0.3 GPM/HP. It should, however, be at least 0.1 GPM/HP to ensure sufficient sealing liquid flow to properly operate the pump; such as to allow, for example, proper filling of the interstices and lubrication. The abbreviation GPM is gallons per minute and the abbreviation HP is horse power. HP approximates power consumed. The volume of sealing liquid passing along the entry area  26  during the running mode compared to the work done by the volume of gas entering the gas entry  29  during the running mode should not exceed a ratio, sealing liquid to power consumed, of more than 0.75 GPM/HP. It should, however, be at least 0.2 GPM/HP to ensure sufficient sealing liquid flow to properly operate the pump; such as to allow, for example, proper filling of the interstices and lubrication. The volume of gas to work done by the pump in each case is measured in cubic feet per minute/HP. Surprisingly the performance of the compressor type liquid ring pump package  17  measured in terms of cubic feet per minute during the running mode over the entire operating pressure range decreases only 5% compared to having the entry area outside of the gas flow path  35   a.  For instance there is only a 5% decrease in efficiency as compared to having an entry area at the cone seal area  43 . With respect to the startup mode there is only a 3-5 percent decrease in efficiency as compared to having an entry area at the cone seal area  43 . To provide a vacuum at the space of the entry area  26  during startup a restrictor valve  45 , (sometimes referred to as an inlet valve or an intake valve) can be used. The restrictor valve  45  is preferably proximate the gas entry  29  opening into the pump head inlet channel  31 . It can be upstream or downstream of the gas entry  29 . It is upstream of the exit of the inlet channel  31  and upstream of the inlet port  33 . It is always upstream of the entry area  26 . To provide the vacuum at the space of the entry area  26 , at startup, the restrictor valve  45  would be in a restricted orientation. The restricted orientation allows less volume of gas to pass through the valve per unit of time than if the valve  45  is in an unrestricted orientation. Therefore during startup, if the valve  45  is in the restricted orientation a vacuum exists downstream of the valve  45 . A vacuum exists at the entry area. The vacuum means a greater absolute pressure difference exists between the pressure Pi at the entry area  26  and the pressure Pd of the sealing liquid along the distal portion  21   b  than if the valve  45  is in the unrestricted orientation. The greater pressure difference increases the flow of sealing liquid passing into space of the entry area  26  from the proximate portion  21   a  of the sealing liquid flow path. Once the liquid ring pump package  17  enters into its running mode, such as for example, the rotor reaches its rated speed or the discharge at the discharge outlet  13  reaches its rated pressure or flow, the valve  45  is oriented into the unrestricted orientation. Even when the valve  45  is in the unrestricted orientation, the sealing liquid will continue to flow into the space of the entry area  26  at a sufficient volume per unit of time. The pressure Pi at the space is still sufficiently less than Pd at the distal portion  21   b  to allow for sufficient sealing liquid flow Pd in the running mode, compared to Pd during startup has increased. 
         [0020]    The compressor type liquid ring pump package  17  can include a second entry area  49  and second sealing liquid flow path  47 . The second sealing liquid flow path  47  is also in fluid connection with the sealing liquid reservoir  19 , separator  11 , and pump discharge outlet  13 . The second sealing liquid flow path  47  is downstream of each of these items. The second entry area  49  is in a location of the pump different from a location of the first entry area  26 . The second entry area  49  is outside of the space which the first entry area  26  comprises. The second entry area  49  is outside of the inlet channel  31  in the pump head  15 . The second entry area  49  is also oriented outside of the space formed by the buckets and the liquid ring in the intake zone of the working chamber. The second entry is outside of the gas flow path  35   a.  The second entry area  49  and its space preferably comprise the cone seal area  43 . The cone seal area is an area proximate where interstices exist between the cone  51  and shaft  41  at an end portion of the cone opposite its nose. The second entry area  49  is downstream of a proximate portion  47   a  of the second sealing liquid flow path  47 . The proximate portion  47   a  is in fluid connection with the reservoir  19  but more proximate to the second entry area  49  than it is to the reservoir, the structure  27  connecting the reservoir  19 , and the second sealing liquid flow path  47  as measured along the second sealing liquid flow path  47 . A distal portion  47   b  of the second sealing liquid flow path is more proximate to the reservoir  19  and structure  27  than it is to the entry area  49 . The proximate portion  47   a  is closer to the second entry area than the distal portion. The distal portion  47   b  is closer to the sealing liquid supply than the proximate portion  47   a.  The proximate portion  47   a  and distal portion  47   b  are in fluid connection with each other and upstream of the second entry area  49 . The proximate portion is upstream of the distal portion. The sealing liquid supply can be the reservoir  19 . 
         [0021]    The second entry area  49  during startup is at a pressure Pii close to the pressure of the sealing liquid Pd 2  along distal portion  47   b  of the second sealing liquid flow path  47 . The pressure at said second entry area  49  is greater than said pressure at said first entry area  26  during startup. Also during startup, the pressure at the second entry area  49  is closer, in absolute terms, to the pressure of sealing liquid along the distal portion  47   b  of the second sealing liquid flow path  47  than the pressure at the first entry area  26  is to said pressure of sealing liquid along said distal portion  21   b  of the first sealing liquid flow path  21 . The pressure Pii at the second area  49 , however, during the running mode, is much less than the pressure Pd 2  of the sealing liquid along the distal portion  47   b  of the second sealing liquid flow path. The pressure difference is sufficient to allow a sufficient volume of sealing liquid to flow into the second entry area to properly operate the pump during the running mode without the use of an extra pump. Proper operation includes filling the interstices and lubrication. 
         [0022]    The second sealing liquid flow path  47  can share a common overlapping portion with the first flow path  21 . In the shown embodiment,  21   b  and  47   b  are common. Alternatively the second flow path can be considered to simply be the portion  47   a  that branches off from the first flow path  21 . In either case, the first and second flow paths are in flow connection with each other and at least one flow path is open to the other. Alternatively, the flow paths could be separate and do not overlap, and neither could open directly to the other. They would however each open to a common sealing liquid supply such as the reservoir  19 . Alternatively, the common sealing liquid supply can be portions  21   a  and  47   a.  The first path could be just portion  21   a  and the second path could be just portion  47   a.  In all cases the first and second flow paths are in fluid connection. 
         [0023]    If a second sealing liquid flow path  47  is used, a valve  53 , in-line with and along said first flow path  21  is preferably used to close and seal a portion of the first sealing liquid flow path  21  and more preferably at least a portion of the proximate portion  21   a  to the first entry area  26 . The valve is preferably, in a flow direction, between the first entry area  26  and the distal portion  21   b  of the first sealing liquid flow path. The valve is preferably upstream of where the first flow path  21   a  opens into a common sealing liquid supply  21   b,    47   b  of the first  21   a  and second  47   a  flow paths. The valve  53  is preferably in fluid connection with the second sealing liquid flow path  47   a.  The valve has a first open orientation wherein the sealing liquid may flow along the proximate portion  21   a  and through the valve  53  into the first entry area  26 . The valve has a second closed orientation wherein the valve  53  prevents sealing liquid from flowing along the proximate portion  21   a  and through the valve  53  into the first entry area  26 . The valve  53  can be a solenoid valve responsive to operational characteristics such as discharge pressure, inlet pressure and/or operating speed of the motor or other prime mover driving the shaft. The valve would change between the closed and open orientation based on the operational characteristics. The valve can also be a mechanical type valve responsive to discharge pressure. The valve would change from an open to a closed orientation based on discharge pressure. For instance the mechanical valve  53  could be a check valve which closes when the pressure of the sealing liquid in the distal portion  21   b  sealing liquid flow path exceeds a predetermined pressure. 
         [0024]    In addition to the above valve  53 , a second valve  55  can be used in the package. The second valve  55  closes and seals off a portion of the second sealing liquid flow path  47  and preferably from a portion of the proximate portion  47   a  of the second sealing liquid flow path to the second entry area  49 . The valve  55  is preferably, in a flow direction, between the second entry area and the distal portion  47   b  of the second sealing liquid flow path  47 . The valve  55  is preferably upstream of where the second flow path  47   a  opens into a common sealing liquid supply  21   b,    47   b  of the first and second flow paths. The valve  55  is preferably in fluid connection with the first sealing liquid flow path  21   a.  The valve  55  has a first open orientation wherein the sealing liquid may flow along the proximate portion  47   a  and through the valve  55  into the second entry area  49 . The valve  55  has a second closed orientation wherein the valve  55  prevents sealing liquid from flowing along the proximate portion  47   a  and through the valve  55  into the second entry area  26 . The valve can be a solenoid valve responsive to operational characteristics such as discharge pressure, inlet pressure and/or operating speed of the motor or other prime mover driving the shaft. The valve  55  would change between the closed and open orientation based on the operational characteristics. In general, the valve  55  would be open when the pressure of the sealing liquid in the distal portion  47   b  of the second sealing liquid flow path is sufficiently greater than the pressure in the second entry area  49  to allow for a sufficient flow of sealing liquid. 
         [0025]    In operation, the pump shaft  41  in the startup mode begins to rotate about its axis. The rotor  39  begins to rotate about its axis which can be coextensive with the shaft axis. After the start of rotation of the shaft  41  and rotor  39 , while still in the startup mode, such as after the elapse of at least 30-60 seconds from the start of rotation on small size compressors, 60-120 seconds on larger units, a sufficient pressure difference is established between the pressure Pi at the first entry  26  and the pressure Pd of the sealing liquid in the distal portion  21   b  of the first sealing liquid flow path. The pressure difference is sufficient when Pi is less than Pd in absolute terms to ensure sufficient flow of sealing liquid. The orientation of the entry  26  and the rotation of the rotor  39  create the sufficient pressure difference between Pi and Pd such that Pi is sufficiently less than Pd. The pressure in the inlet channel  31 , for instance, as a result of the orientation and initial rotation is sufficiently less than Pd. The pressure Pi, is actually reduced by the rotation. The pressure Pi is preferably around zero Psi. The pressure difference is preferably from at least 3 psi to 5 psi to overcome pressure drops. As a result of the sufficient pressure difference, sealing liquid flows into the entry area  26 . From the entry area  26 , the sealing liquid flows into the interstices  37 , such as the interstices between the cone and shaft at the cone seal area  43 . The volume of sealing liquid passing along the entry area  26  at startup compared to work done by the volume of gas entering the gas entry  26 , work done approximated by power consumed, is kept to a ratio of sealing liquid to power consumed is of no more than 0.3 GPM/HP. It should however be at least 0.1 GPM/HP to ensure sufficient sealing liquid flow to properly operate the pump, such as fill the interstices and provide lubrication. The pressure difference is obtained without the use of the extra pump such as having an extra pump in fluid connection with the first entry area  26  or the first sealing liquid flow path  21 . 
         [0026]    As the shaft  41  and rotor  39  continues to rotate, the pressure of Pd increases. After a period of time from the start of rotation such as at least 30-60 seconds on small compressors and about 60-120 seconds on large compressors, the pump package  17  is in its running mode of operation. In the running mode, the pump package  17  has reached its operating, desired or rated speed and its operating, desired, or rated discharge flow or pressure. In the running mode, the pressure Pd of the sealing liquid along the distal portion  21   b  of the first sealing liquid flow path  21  is still sufficiently greater than Pi at the first entry area  26 . The pressure difference is at least 3 psi to 5 psi. Unless a second flow path  47  is used, the sealing liquid will continue to flow into the first entry area  26  during the running mode. The volume of sealing liquid passing along the entry area  26  during the running mode compared to work done by the volume of gas entering the gas entry and resulting power consumed is kept to a ratio of liquid volume to power consumed of no more than 0.75 GPM/HP. It should however be at least 0.2 GPM/HP to ensure sufficient sealing liquid flow. 
         [0027]    In the embodiment having the second sealing liquid flow path  47 , when the rotor  39  and shaft  41  first begin to rotate about their axis the pressure Pii at the second entry area  49 , such as the cone seal area  43 , is not sufficiently less than the pressure Pd 2  in the distal portion  47   b  of the second sealing liquid flow path  47  to ensure sufficient flow. After the start of rotation of the shaft  41  and rotor  39 , while in the startup mode, such as after the elapse of at least 30 seconds on small compressors and about 60 seconds on large compressors, from the start of rotation, the pressure Pii is still not sufficiently less than the pressure Pd 2  of the sealing liquid in the distal portion  47   b  of the second sealing liquid flow path. After a period of time, from the start of rotation, such as at least 70 seconds on small compressors and about 140 seconds on large compressors, the pump package  17  is in its running mode. In the running mode, the pressure Pd 2  of the sealing liquid along the distal portion  47   b  of the second sealing liquid flow path  47  is sufficiently greater than Pii at the second entry area  49  to allow sufficient flow. Sufficient flow as stated allows for proper operation of the pump such as the filling of interstices with the sealing liquid and lubrication of the pump. The rotation of the rotor  39  increases the pressure difference between Pii and Pd 2  such that Pd 2  is sufficiently greater than Pii to provide a sufficient pressure difference. As stated a sufficient pressure difference means a sufficient flow. Preferably, the valve  53  between the first entry area  26  and the distal portion  21   b  of the first sealing liquid flow path  21  is oriented to the closed orientation from an open orientation. The flow along the first sealing liquid introduction path  21  and in particular the proximate portion  21   a,  into the first entry area  26  is stopped. The flow along the second sealing liquid flow path  47 , and in particular, along the proximate portion  47   a  of the second sealing liquid entry path  47  into the second entry area  49  starts and continues. 
         [0028]    In an embodiment, the second valve  55  between the second entry  49  and the distal portion  47   b  of the second sealing flow path is placed in an open orientation from a closed orientation. The flow of liquid through the valve  55  into the second entry area  49  from the proximate portion  47   a  is permitted. Preferably the second valve  55  is placed in the open orientation at a time at or after the pump package  17  enters into its running mode of operation and also after the first valve  53  is placed in the closed orientation. 
         [0029]    The operating radial clearance  57  between the cone  51  and the elongated lateral free edges  59  of the rotor  39  (clearance varies with pump size, operating pressure capabilities and lobe design single or double which controls shaft deflection) is maintained to at least 0.01 inches on small compressors, and could be as high as 0.05 inches on large compressors. The free edges of the rotor  39  extend in a direction along a length of the shaft and define a cavity  61  to receive the cone  51 . The flowing of the sealing liquid into the first entry area and second area is done without the sealing liquid condensing a fluid in a gaseous state to a liquid state. The fluid that the sealing liquid avoids condensing is a fluid that has a liquid state at room temperature and preferably between 70 degree F. and 150 degree F. 
         [0030]    The pump can have a working chamber housing  100  that has a circular inner surface  101  delimiting a circular working chamber. In this case the compressor package is a single lobe design having a single intake zone and compression zone. The pump could be a multiple lobe design. In this case the working chamber housing would have an oval inner surface delimiting an oval working chamber. The working chamber would have two intake zones and two compression zones in an alternating pattern. The two intake zones would be on opposite ends of the minor axis of the oval and the two compression zones would be on opposite ends of the major axis. 
         [0031]    The liquid ring pump of  FIGS. 1 and 2  is operable in a start-up mode or a normal operating mode. Typically, pumps of this type are used as air compressors and the operation of the pump will be described in that context. When the pump is not operating, the pressures within the various regions of the system tend to equalize at or near atmospheric pressure. Thus, the working chamber, the inlet channel, the outlet space, the cone seal area, and the separator including the reservoir tend to return to atmospheric pressure. When it is desirable to start the pump, there is no pressure differential present to move or force the movement of the sealing fluid contained within the reservoir. In prior art pumps, a separate pump might be provided for this function. However, in the illustrated construction, no additional pump is required. 
         [0032]    To start he pump of  FIGS. 1 and 2 , the user initiates a start sequence by initiating rotation of the rotor. The rotor will draw air in through the intake channel as during normal operation. However, the intake valve is moved toward the closed position to throttle the air entering the inlet channel. Further rotation of the rotor thus causes a pressure reduction in the inlet channel as the rotor is capable of compressing or pumping more air than what can pass through the intake valve. The valve  53  located in the first sealing flow path is opened or opens in response to this reduced pressure to create an open fluid flow path between the reservoir and the intake channel. The pressure within the reservoir is still near atmospheric pressure (or slightly higher), thus establishing a pressure differential between the ends of the first fluid flow path that is sufficient to force sealing liquid into the inlet channel. 
         [0033]    Once sufficient fluid is in the pump or the start-up sequence is complete and the pump transitions to normal operation. To transition, the intake valve is moved to the open position and the valve in the first fluid flow path is closed (or closes in response to the increased pressure in the inlet channel). Rotation of the rotor during the start-up phase has resulted in a quantity of compressed air exiting the rotor at the outlet space. This compressed air increases the pressure in the outlet space and in the separator. Thus, the pressure in the reservoir has now increased to some value above atmospheric pressure. The pressure in the cone seal area is around atmospheric pressure (or slightly less). The second flow path provides fluid communication between the cone seal area and the reservoir with the aforementioned pressure differential providing the force needed to push sealing liquid from the reservoir into the cone seal area. The second valve, positioned in the second fluid flow path is either opened or opens in response to this pressure differential to assure the desired flow. 
         [0034]    The term gas as use herein is broad enough to include, without limitation, ambient air, fluids in a gaseous state other than ambient air, mixtures of gases, other than ambient air, with ambient air and/or non-ambient gases, and mixtures of incompressible and compressible fluids, vaporized liquids mixed with ambient air, and also vaporized liquids. The phrase “smaller compressors” means no more than 50 HP. The term “larger compressor” means at least more than 50 HP.