Pumps – Condition responsive control of pump drive motor – By stopping pump in response to leakage into or from system
Patent
1997-10-17
2000-07-11
Thorpe, Timothy S.
Pumps
Condition responsive control of pump drive motor
By stopping pump in response to leakage into or from system
417 441, 417 13, 4174233, 41742311, 417372, F04B 4910
Patent
active
060863315
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a safety pumping system which includes a pump and an electric motor, and which is adapted to be immersed in a fluid contained in a tank various inflammable fluids, such as liquid petroleum products, liquified gases and various hazardous chemical liquid products are usually stored in large tanks, for example in tankers when the liquid is transported, or in stationary tanks on land. The inflammable liquid may be delivered to and/or discharged from such tanks by means of pumps, such as special centrifugal pumps. Such deep well pumps, which are located adjacent to the bottom of the tank, may be driven by an electric motor provided that the motor is of an explosion proof design and positioned above the top wall of the tank. A long driving shaft may then extend from the motor, through the well and down to the pump. Such long driving shaft requires a large number of bearings, and on board of a ship a high positioning of several such rather heavy electric motors contributes to instability because the center of gravity is being moved upwardly.
Another possibility is to use a hydraulic motor for driving the pump. Because such hydraulic pump does not contain any source of ignition it may be arranged within the tank close to the pump. However, such hydraulic pump is disadvantageous because it needs a supply of high pressure oil via a complicated hydraulic supply system. Furthermore, driving oil leaking from the hydraulic system may penetrate into the tank and contaminate the fluid contained therein.
A safety pumping system of the above type allowing the use of an electric driving motor positioned within the tank close to the pump is disclosed in U.S. Pat. No. 5,336,064. A motor housing surrounding the driving motor defines an inner space and is surrounded by an outer shell. The motor housing contains a non-hazardous liquid, such as oil, that displaces oxygen in the inner space of the motor housing so that explosions due to an electric spark caused by failure of the electric motor are resisted. The outer space defined between the motor housing and the outer shell is filled with an inert atmosphere so as to isolate the electric motor from the hazardous liquid in the surrounding space of the tank.
In this known pumping system the liquid contained in the inner space of the motor housing is used for cooling the motor and for lubricating and cooling bearings and seals. However, the use of two different fluids, namely a liquid in the inner space of the motor housing and an inert gas in the space defined between the motor housing and the outer shell, substantially complicates the pumping system and involves the risk of contamination of the fluid within the tank with oil or another liquid leaking from the inner space of the motor housing.
The present invention provides a pumping system of the type described above in which only one fluid, namely a protective gas, is needed for obtaining an explosion proof immersed pumping system with an electric driving motor.
Thus, the present invention provides a safety pumping system, which includes a pump and an electric motor, and which is adapted to be immersed in a fluid contained in a tank, said system comprising a motor housing enclosing the electric motor, an outer shell or jacket defining an outer space surrounding the housing of the motor, a driving shaft interconnecting the electric motor and the pump, and first gas supply means for supplying protective gas into the outer space at a pressure exceeding the atmospheric pressure, so as to fill the outer space with such gas, and the pumping system according to the invention is characterized in that the motor housing defines an inner space containing the electric motor, second gas supply means being provided for supplying protective gas into the inner space so as displace oxygen therefrom and fill the space with protective gas in order to counteract explosions, the second gas supply means being adapted to maintain the protective gas in the inner space at a pressure, which is equal to or exceeds that of t
REFERENCES:
patent: 4087204 (1978-05-01), Niedermeyer
patent: 5336064 (1994-08-01), Lamers
Moses Daniel E.
Svanehoj International A/S
Thorpe Timothy S.
LandOfFree
Safety pumping system for hazardous environments using pressuriz does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Safety pumping system for hazardous environments using pressuriz, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Safety pumping system for hazardous environments using pressuriz will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-535640