Patent Application
20140251573
1. Field of the Invention
The present invention relates to a mechanical seal cooler that will allow cooling the hot water around a mechanical seal in a high pressure, high temperature, hot water centrifugal pump.
2. Description of the Related Art
Centrifugal pumps are pumps that use a rotating impeller to increase the pressure of a fluid. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flows radially outward into a diffuser or chamber of a volute, from where it exits an outlet, and into a downstream piping system. A centrifugal pump typically includes a rotating impeller that increases the velocity of the incoming fluid. A casing, or volute, of the pump then acts to convert this increased velocity into an increase in pressure, resulting in fluid flow. A centrifugal pump in its most basic configuration comprises a hollow casing shaped to contain a suction port and a discharge port, as well as one or more entry points through which a rotating shaft traverses the casing. An impeller is fastened to the shaft and is located approximately in the center of the casing. The shaft is supported by bearing brackets fastened to the outside of the casing. These brackets contain ball bearings that support the shaft and allow it to spin when coupled to an electric motor, and allow the impeller to perform the required pumping by taking the water coming from the suction port and pushing it centrifugally out of the discharged port. At the points where the shaft enters the casing, the water in the casing is contained and prevented from spilling out into the environment. Centrifugal pumps which operate at high temperatures, e.g., up to about and exceeding 400° F., typically incorporate features designed to protect the motor and seals from the high temperature of the working fluid in the pump housing.
The traditional way of accomplishing this task, has been to shape the entry points of the casing like a tube. The axis of this tube coincides with the axis of the rotating shaft. The space between the outside diameter of the shaft and the inside diameter of the tube, such as about ½″ to ¾″, would be filled with several rope packing rings so as to fill the cavity with pressure and reduce the leakage to a minimum. The tubular area where this rope packing is stuffed is commonly referred as a stuffing box. In the last 30 to 40 years there has been an increased intolerance for pumps fitted with rope packing and a way of accomplishing a seal at the entry points of the shaft into the casing, which is referred to as mechanical seal. In the simplest arrangement a mechanical seal has two components, a stationary annular component fitted into the stuffing box, and a rotating head which is spring loaded and fastened to the shaft. The stationary component is composed of a hard material such as silicon carbide and the rotating component is a softer, sacrificial material such as carbon. There would be an interface in a plane perpendicular to the shaft axis between the rotating carbon component and the stationary components.
The constant friction of the components generates heat which needs to be flushed with water at about 140° F. to 180° F. This need is even more prevalent when the water being pumped is already around 400° F. to 500° F.
Centrifugal pumps may also be air cooled. In this regard, U.S. Pat. No. 8,152,458 provides a tube heat exchanger in fluid communication with the seal housing interior reservoir. The heat exchanger is a coil type heat exchanger having inlet and outlet ends connected to the seal housing with the coil extending exterior to the seal housing. Lubricating fluid in the seal housing reservoir is directed into the inlet end of the heat exchanger, travels through and cools the coil, and then returns to the seal housing reservoir through the outlet end of the heat exchanger. The lubricating fluid is constantly recirculated and cooled through the seal housing reservoir, thus increasing the amount of heat carried away from the lubricating fluid which protects the mechanical seal from heat damage. The coil is adjacent a cooling fan located between the motor and seal housing. U.S. Pat. No. 8,092,154 provides an integrated fan plus a pump and heat exchanger housed in a cooling system. Air cooling is provided via an airflow created by the axial-flow fan, liquid cooling is provided via the centrifugal pump, and a heat transfer process is performed at the surface of drilled pump diffuser elements of the centrifugal pump where heat transfers from the relatively hot liquid to the air stream. U.S. Pat. No. 6,973,782 provides a pressurized hydraulic fluid system including a main pump and a charge pump provided for maintaining a sufficient inlet head pressure in the main pump. A heat exchanger and an electric motor driven cooling fan associated with the heat exchanger force cooling of hydraulic fluid flowing through the heat exchanger. U.S. Pat. No. 4,236,572 provides a fluid cooled heat exchanger system comprising a heat exchanger, first conduit means connected to the heat exchanger, a pump for pumping a cooling fluid to the heat exchanger via the first conduit means, second conduit means for receiving fluid from the pump that is in excess of the heat exchanger requirements. A valve is connected to the first and second conduit that fluid that has passed through. The heat exchanger via the first conduit means mixes in the valve with fluid that has by-passed the heat exchanger via the second conduit means, and the valve having a movable valve element which is moved off a valve seat by an amount dependent on the flow of fluid in the second conduit means. The flow of fluid through the heat exchanger is maintained substantially constant. By providing a substantially constant fluid flow through the heat exchanger, a substantial pressure drop across the heat exchanger at maximum fluid flow from the pump can be avoided. U.S. Pat. No. 4,069,906 discloses a cooling apparatus for drives having a housing containing a sump for a fluid which is heated by the generation of heat energy during operation of the drive. A centrifugal pump is driven by the input shaft and circulates fluid to a heat exchanger disposed about the outside surface of the housing. The cooled fluid is returned to a fluid sump which assures an ample supply of fluid at a relatively low pressure. A fan carried by an input shaft blows ambient air over the heat exchanger and exterior surface of the housing to enhance the level of heat dissipation.
The present invention provides an improved seal cooler which works by piping pump discharge water at around 400° F. into one side of the inventive cooler and piping water at around 50° F. to 65° F. on the other side of the seal cooler. The hot water enters the cooler in the center and exits on the outer port, while cold water enters the cooler in the outer port and exits at the center. This arrangement allows the two fluids to run counter each other and increases the heat exchange rate. Previous seal coolers had a tendency to clog and deteriorate prematurely due to the galvanic action between the different materials of construction such as copper and steel.
The invention provides a mechanical seal cooler which comprises a solid body; a continuous first conduit disposed within the body and defining first conduit side walls; a continuous second conduit disposed within the body and defining second conduit side walls;
the first conduit being spaced from and in juxtaposition with the second conduit;
a first fluid inlet port extending through the body cooperating with an input end of the first conduit, and a first fluid outlet port extending through the body cooperating with an outlet end of the first conduit;
a second fluid inlet port extending through the body cooperating with an input end of the second conduit and a second fluid outlet port extending through the body cooperating with an outlet end of the second conduit;
a plurality of concavities through the first conduit side walls and a plurality of concavities through the second conduit side walls; and
a coupling for attaching the solid body to a heat source device.
The invention also provides a method for cooling a heat source device which comprises
a) providing a heat source device, and
b) coupling the heat source device to a mechanical seal cooler;
the mechanical seal cooler comprising a solid body; a continuous first conduit disposed within the body and defining first conduit side walls; a continuous second conduit disposed within the body and defining second conduit side walls;
the first conduit being spaced from and in juxtaposition with the second conduit;
a first fluid inlet port extending through the body cooperating with an input end of the first conduit, and a first fluid outlet port extending through the body cooperating with an outlet end of the first conduit;
a second fluid inlet port extending through the body cooperating with an input end of the second conduit and a second fluid outlet port extending through the body cooperating with an outlet end of the second conduit;
a plurality of concavities through the first conduit side walls and a plurality of concavities through the second conduit side walls; and
a coupling for attaching the solid body to the heat source device;
c) passing a stream of a first fluid into the first fluid inlet port and the input end of the first conduit, through the outlet end of the first conduit and the first fluid outlet port;
d) passing a stream of a second fluid out of an exit end of a conduit of the heat source device into the second fluid inlet port and the input end of the second conduit, through the outlet end of the second conduit and the second fluid outlet port, and returning the second fluid to an input end of the conduit of the heat source device.
A suitable coupling, such as threaded piping, attaches the solid body to a heat source device, which is preferably a centrifugal pump. Another suitable coupling, such as threaded piping, attaches the solid body to a water supply source. Thus a hot water outlet conduit from a centrifugal pump is coupled to an inlet port of hot side outer disk 20 which cooperates with hot water inlet end 44 of central disk 18. A hot water inlet conduit from a centrifugal pump is coupled to an outlet port of hot side outer disk 20 which cooperates with hot water outlet end 46. Another suitable coupling comprises a plurality of bolts coupling the solid body to a heat source device.
Cold water outlet from a municipal supply is coupled to an inlet port of 24 of cold side outer disk 16 which cooperates with cold water inlet end 34 of central disk 18. A cold water conduit back to a municipal supply is coupled to an outlet port of cold side outer disk 16 which cooperates with cold water outlet end 36.
In use, one passes a stream of a first fluid, such as water, into the first fluid inlet port 24 and the input end 34 of the first conduit 30, and passes the now heated water through the outlet end 36 of the first conduit 30 and the first fluid outlet port 26 back to a water supply source or to a drain. One passes a stream of a hot second fluid out of an exit end of a conduit of the heat source device into the second fluid inlet port and the input end 44 of the second conduit 40, through the outlet end 46 of the second conduit 40 and the second fluid outlet port, and returning the now cooled second fluid to an input end of the conduit of the heat source device.
In one embodiment of the invention, the first conduit 30 and the second conduit 40 are spiral shaped. In another embodiment the first conduit 30 and the second conduit 40 are spiral shaped and they are concentrically aligned, such as on opposite sides of central disk 18. Alternately, conduits 30 and 40 may be milled completely through central disk 18 such that they are juxtaposed with one another in an interdigitated fashion such that their fluids do not intermix. In one embodiment the heat source device is a pump, such as a mechanical pump, however, it can also be any other device containing a flow of hot fluid which must be cooled. The solid body members may be composed of any suitable materials, such as metals, in particular, stainless steel, copper, aluminum or combinations thereof. Further embodiments of the invention dispose a suitable thermometer at one or both of the first fluid outlet port and the second fluid outlet ports. Further embodiments of the dispose a pressure gauge at one or both of the first fluid outlet port and the second fluid outlet ports.
In a typical operation, the stream of the first fluid passing into the first fluid inlet port has a pressure of from about 50 psi to about 75 psi and a temperature of from about 55° F. to about 80° F., preferably from about 55° F. to about 65° F., and the stream of the first fluid passing out of the first fluid outlet port has a pressure of from about 50 psi to about 75 psi and a temperature of from about 150° F. to about 200° F.
In a typical operation, the stream of the second fluid out of an exit end of the conduit of the heat source device into the second fluid inlet port has a pressure of from about 300 psi to about 500 psi and a temperature of from about 350° F. to about 500° F. and the stream of the second fluid passing through the outlet end of the second conduit and the second fluid outlet port and returning the second fluid to an input end of the conduit of the heat source device has a pressure of from about 300 psi to about 500 psi and a temperature of from about 100° F. to about 160° F., preferably from about 120° F. to about 140° F.
While the present invention has been particularly shown and described with reference to preferred embodiments, it will be readily appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the claims be interpreted to cover the disclosed embodiment, those alternatives which have been discussed above and all equivalents thereto.
