Patent Publication Number: US-11396882-B2

Title: Gas seal column pump

Description:
COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/973,219 filed Sep. 20, 2019, entitled “Gas Seal Column Pump”. 
     BACKGROUND 
     In the pumping world dominated by horizontal pumps of all different styles, mechanical seals or shaft packing glands are the most troublesome and highest maintenance cost items over all other pump components. 
     SUMMARY OF THE INVENTION 
     The answer to eliminating these problems and their associated expenses is to remove both components and reposition the pump components vertically with a gas seal column encasing a drive shaft between a drive motor and a pump. The drive motor, the gas seal column, and the pump may form a hermetically sealed unit that is pressurized for product containment. 
     These numerous benefits, and other numerous benefits listed herein, may be realized by utilizing the invention:
         With a gas seal column there is no contact between rotating and stationary components of the pump, thereby allowing for a continuous run dry capability. Run dry capability may result in the elimination of friction, heat, mechanical wear, power loss, high initial cost, installation cost, replacement cost, and collateral damage cost of mechanical seal and packing when they inevitably fail and Significantly reduces the possibility of product leakage requiring cleanup and reporting to an oversight or authoritative body.   A gas seal column, through the use of product monitoring sensors, also allows for continuous timely product control, reporting, operator alerting, and, if needed, controlled automatic shutdown of pumping operations to prevent equipment and collateral damage. In contrast, seal and packing failures may announce themselves with a large puddle on the floor.   Combining a gas seal column with hermetically sealing all components of the pumping system together allows for:
           Improved internal atmosphere control to prevent corrosion of internal components, especially motor bearings.   Improved product control with essentially no possibility of product escaping the containment envelope, possibly causing employee injury or nearby equipment damage.   In many cases eliminating the cost of a bearing pedestal by using a hermetically sealed extended shaft motor with a corrosion resistant sleeve to protect the extended motor shaft.   
               

     Considering all of the above it can easily be expected that the total life cycle cost of a gas seal column pump will be significantly lower than for a similar performing mechanical seal or packing pump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain illustrative embodiments illustrating organization and method of operation, together with objects and advantages may be best understood by reference to the detailed description that follows taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of a hermetically sealed gas seal column pump consistent with certain embodiments of the present invention and illustrating a pump drive, a gas seal column, a seal gas control box, and a pump. 
         FIG. 2  is a cross-sectional view of a hermetically sealed gas seal column pump consistent with certain embodiments of the present invention and illustrating a bearing shaft adapter used in conjunction with a pump drive, a gas seal column, and a pump. 
     
    
    
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure of such embodiments is to be considered as an example of the principles and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. 
     The terms “a” or “an”, as used herein, are defined as one or more than one. The term “plurality”, as used herein, is defined as two or more than two. The term “another”, as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open language). The term “coupled”, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. 
     Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment” or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments without limitation. 
     The gas seal column pump (hereinafter invention) may comprise a pump drive, a gas seal column, a seal gas control box, and a pump. The pump drive may comprise a drive motor and a cooling fan. The drive motor may comprise a drive shaft that is extended to reach the pump through the gas seal column. The drive motor may further comprise a pressurized housing. The cooling fan may be coupled to the drive motor externally to cool the drive motor instead of driving a fan from an extension of the drive shaft of the drive motor through the top of the drive motor. Alternatively, ducted cooling from a remote source may be used to cool the drive motor. 
     The drive motor may comprise a gas inlet pipe for a seal gas to be introduced into the drive motor adjacent to an upper motor bearing. The drive motor may further comprise a plurality of gas outlet ports located adjacent to a lower motor bearing for the seal gas to exit the drive motor while protecting the lower motor bearing. 
     The seal gas may be clean and pressurized and may be sourced locally or remotely. The first choice for the seal gas would be clean air that is free of corrosive fumes. Alternatively, a specialized gas may be used if air is incompatible with a product being pumped. If the seal gas that is selected to be used cannot be released to the environment after use because of cost, toxicity, contamination, or other reasons then the seal gas may be directed to a local gas treatment system or collected in a tank for later treatment. After treatment, the seal gas may be reused or disposed of. 
     The gas seal column may be operable to encase the drive shaft component of the pumping system and may function as a replacement for mechanical seals and packing by using pressure of the seal gas to control a product level within the gas seal column, when pumping or in standby, when gas seal column controls are activated. 
     The gas seal column may comprise a mounting panel at the top end of the gas seal column. A circular groove in the mounting panel may capture a first O-ring which is operable to pressure seal the interface between the drive motor and the gas seal column. 
     An inlet pipe connection and an outlet pipe connection located in the upper quarter of the gas seal column may allow the seal gas to flow in and out of the gas seal column. A purge gas valve and a purge gas discharge valve may control the flow of the seal gas. The seal gas may flow constantly through the drive motor to keep out the corrosive fumes given off by the product. 
     The gas seal column may comprise a plurality of splash quieting discs. In a preferred embodiment there may be four splash quieting discs. The gas seal column may further comprise a plurality of anti-rotation panels. In a preferred embodiment there may be two sets of anti-rotation panels. The decision to use the plurality of splash quieting discs and/or the plurality of anti-rotation panels or a combination of both may be dictated by the application. 
     The gas seal column may comprise a plurality of level sensors. The plurality of level sensors may detect the product level within the gas seal column and may report the product level to the seal gas control box. Based upon input from the plurality of level sensors, the seal gas control box may be adapted to monitor the product level, may report the product level, may alert an operator, and may control the product level of the product that may come into the gas seal column during operating or non-operating conditions, when the seal gas control box is energized by a purge gas control switch. As a non-limiting example, the seal gas control box may be adapted to alert the operator by activating flashing indicators, sending text messages, pages, or emails, sounding audible transducers, or combinations thereof if the product level exceeds a predetermined alert threshold. As a further non-limiting example, the seal gas control box may shut down the pump and possibly other components if the product level exceeds a predetermined shutdown threshold. 
     In a preferred embodiment there may be four level sensors. In some embodiments, the four level sensors may be equally spaced along the gas seal column. A first level sensor may be located at the lowest level of the gas seal column. A second level sensor, a third level sensor, and a fourth level sensor may be located above the first level sensor in that order, with the fourth level sensor being at the highest level within the gas seal column. 
     At pump start up, the purge gas control switch may be activated manually or automatically. Responsive to activating of the purge gas control switch, the seal gas control box may begin a low volume purge gas flow throughout the system by opening a purge gas valve and leaving a first gas valve and a second gas valve closed. In some embodiments, the opening and closing of the purge gas valve, the first gas valve, a second gas valve, and the gas discharge valve may be controlled by relays or other controls located within the seal gas control box. 
     In some embodiments, the purge valve, the first gas valve, and the second gas valve may provide differing flow rates of the seal gas when in the open state. The differing flow rates may result in differing pressures applied to the product within the gas seal column. The smallest flow rate, and therefore the lowest pressure on the product within the gas seal column, may result from having only the purge valve open. The highest flow rate, and therefore the highest pressure on the product within the gas seal column, may result from having the purge valve, the first gas valve, and the second gas valve all open. Because the seal gas may be introduced into the top of the gas seal column, the pressure applied to the product from the seal gas may work to force the product level down. 
     The seal gas control box may become aware that the product has entered the gas seal column when the first level sensor detects the product and opens the purge gas valve. If the product is detected by the second level sensor, the seal gas control box may attempt to stop the product from rising further in the gas seal column by increasing the pressure of the seal gas within the gas seal column. The seal gas control box may open the first gas valve, thus releasing a higher flow of the seal gas into the drive motor and into the gas seal column. If this works and the product level drops then the second level sensor may reflect that the product is no longer contacting the second level sensor. However, the seal gas control box may retain the first gas valve in the open state. When the first level sensor indicates that the product level has dropped below the first level sensor, the seal gas control box may close the first gas valve, the purge gas valve, and the gas discharge valve. 
     Alternatively, if the product level continues to rise above the second level sensor and is detected by the third level sensor, the seal gas control box may activate and latch a relay that opens the second gas valve, thus releasing an even higher flow of gas into the drive motor and the gas seal column to further increase gas pressure to push the product down in the gas seal column. The seal gas control box may additionally be adapted to send an alert to the operator reporting that the product is appearing at a higher level in the gas seal column than is normally expected. The higher level of gas flow will continue until the product is driven down to the first level sensor which will open and deactivate the two latched relays that will then close the first gas valve, the second gas valve, the purge gas valve, and the gas discharge valve. 
     Alternatively, if the product level continues to rise and is detected by the fourth level sensor, the seal gas control box may be adapted to initiate a controlled, complete shutdown of the system and close all valves to maintain the hermetically sealed integrity of the total pump housing and to prevent equipment damage or other collateral damage from occurring. This shutdown sequence allows the operator to investigate what is causing the condition and to correct the problem. 
     The first level sensor may be located slightly above the minimum priming level for the pump. When the pump is stopped, inlet or outlet conditions may cause the product to rise or drop in the gas seal column. A rise in the product level may be controlled as previously described. Responsive to a drop in the product level below the first level sensor, the seal gas control box may deactivate the relay that holds the purge valve open. Closing the purge valve may stop purge gas flow until the product rises to reach the first level sensor. The seal gas control box may function in this manner whether the pump is operating or in standby mode as long as the seal gas control box is activated. 
     The description of sensing and control presented herein is by way of illustration only. There are many other sensing and control techniques that may be applied which a person having ordinary skill in the art will recognize as falling within the spirit and scope of the invention. 
     The pump illustrated is a centrifugal pump comprising a pump casing with an inlet and an outlet and a second O-ring to seal a cover plate to the pump casing. The pump casing may be hermetically sealed to the gas seal column with a third O-ring, completing the hermetic seal for the entire assemblage. The drive motor, the gas seal column, and the pump may comprise a single, hermitically sealed unit. 
     The pump may comprise a dual impellor to move the product. An auxiliary impellor may be mounted on the back of a main impellor. The auxiliary impellor may be a larger diameter than the main impellor. The auxiliary impellor may constitute a hydrodynamic shaft seal and may prevent the flow of the product into the gas seal column during pumping operations. The auxiliary impellor may not be needed for all applications and may therefore be optional. 
     The drive shaft may be a sleeved shaft to protect the drive shaft from corrosion. 
     The pumping system shown in  FIG. 1  using the drive motor comprising an extended shaft is for illustration only. A person having ordinary skill in the art will recognize that various arrangements of the drive shaft may fall within the spirit and scope of the invention as long as the drive motor is coupled to the pump via the gas seal column. 
     Referring to  FIG. 2 , some applications may require a special shaft of length, diameter, or material of construction not available in an extended shaft drive motor. Applications requiring the drive shaft and the gas seal column to be longer may be accomplished by using a bearing shaft adapter between the drive motor and the gas seal column. The bearing shaft adapter may couple and seal to both the drive motor and the gas seal column such that the assemblage of the drive motor, the bearing shaft adapter, the gas seal column, and the pump are hermetically sealed. The gas seal column may be of any practical length and designed with a plurality of shaft bearing supports and level sensors along the length of the gas seal column to satisfy the requirements of the application. 
     The bearing shaft adapter interfaces may be sealed by an additional O-rings to maintain the hermetic seal integrity of the pump envelope. 
     Since a hermetically sealed unit encloses a fixed volume of empty space, the hermetically sealed unit passively assists in controlling the level of the product trying to rise in the gas seal column. Passive assistance may result from Boyles Law which states that “the pressure of an ideal gas is inversely proportional to the volume of the ideal gas at a constant temperature”.
 
 P 1× V 1= P 2× V 2
 
     where P1 is a first pressure, 
     V1 is a first volume, 
     P2 is a second pressure, and 
     V2 is a second volume. 
     Simply put—if you halve the available volume of a fixed amount of gas you will double the pressure. As a non-limiting example, when the product rises within the gas seal column, the volume available to the seal gas is reduced. In accordance with Boyle&#39;s Law, as the volume of the seal gas is reduced, the pressure of the seal gas increases and the seal gas may become more effective in countering the rise of the product. 
     As experience is gained through the introduction and application of this invention consideration should be given to the operational benefits that might be optimized by decreasing empty space in the motor housing and also the internal shape and size of the gas seal column around the drive shaft, all of which may affect system response time. 
     Turning now to  FIG. 1 , a cross section of the invention  100  through the pump drive  200 , the gas seal column  220 , and the pump  270  is shown. The pump drive  200 , the gas seal column  220 , and the pump  270  may be hermitically sealed to each other. As non-limiting examples, the circular groove  224  on the mounting panel  222 , the first O-ring  226 , the second O-ring  278 , the cover plate  280 , the pump casing  272 , and the third O-ring  282  may prevent air, the seal gas  208 , and the product from leaking in or out. The pump drive  200  may comprise the drive motor  202  and the cooling fan  204 . 
     The gas seal column controls  310 , comprising the seal gas control box  250 , the purge valve  254 , the first gas valve  256 , and the second gas valve  258 , may control the flow of the seal gas  208  into the invention  100  when activated by the purge gas control switch  252 . The seal gas  208  may be introduced into the drive motor  202  via the gas inlet pipe  206  such that the seal gas  208  may protect motor bearings. As non-limiting examples, the seal gas  208  may protect the upper motor bearing  210  and the lower motor bearing  212 . The seal gas  208  may exit from the drive motor  202  via the plurality of gas outlet ports  216 . 
     The seal gas  208  may also flow into the gas seal column  220  via the inlet pipe connection  230  and may exit the gas seal column  220  via the outlet pipe connection  232 . The seal gas  208  may pressurize the gas seal column  220  to force the product downwards. The pressure may be regulated by the seal gas control box  250  by opening and closing the purge valve  254 , the first gas valve  256 , and the second gas valve  258 . The gas discharge valve  234  may prevent or permit the seal gas  208  from exiting the gas seal column  220  and may also be under control of the seal gas control box  250 . The seal gas control box  250  may also control power to the drive motor  202  such that the seal gas control box  250  may shut down the system if necessary. 
     The first level sensor  240 , the second level sensor  242 , the third level sensor  244 , and the fourth level sensor  246  may detect the product level within the gas seal column  220  and may report the product level to the seal gas control box  250 . 
     The drive shaft  214  may turn the main impellor  290  in the pump  270  to move the product from the inlet  274  to the outlet  276 . The auxiliary impellor  292  may be coupled to the main impellor  290  and may constitute a hydrodynamic seal to resist the flow of the product into the gas seal column  220 . The gas seal column  220  may comprise the plurality of anti-rotation panels  238  and the plurality of splash quieting discs  236 . 
     Turning now to  FIG. 2 , a cross section of the invention  100  through the pump drive  200 , the gas seal column  220 , the bearing shaft adapter  300 , and the pump  270  is shown. The bearing shaft adapter  300  may permit the introduction of the special shaft  312  when necessary. As a non-limiting example, the additional O-rings  306  may hermitically seal the bearing shaft adapter  300  to the drive motor  202  and the gas seal column  220 . The plurality of level sensors  304  may detect the product level within the gas seal column  220  and may report the product level to the seal gas control box  250  as in  FIG. 1 . The seal gas  208  may flow through the invention  100  as described in  FIG. 1 . As a non-limiting example, the seal gas  208  may enter the gas seal column  220  via the inlet pipe connection  230  and exit at the outlet pipe connection  232  as permitted by the gas discharge valve. The seal gas  208  may flow through the plurality of shaft bearing supports  302  to push the product level down to whatever product level is required for the gas seal column  220 . 
     While certain illustrative embodiments have been described, it is evident that many alternatives, modifications, permutations and variations will become apparent to those skilled in the art in light of the foregoing description.