US2984991A - Cooling tower and its safe operation - Google Patents

Description

May 23, 1961 R. R. MORGAN 2,984,991 COOLING TOWER AND ITS SAFE OPERATION Filed March 24, 1958 G3 ff) INVENTOR. R.R. MORGAN Hired States Patent Ce. Pale-fed May 23,1961

COOLING TOWER AND ITS SAFE OPERATION Rexford R. Morgan, Phillips, Tex., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Mar. 24, 1958, Ser. No. 723,518

8 Claims. (Cl. 62-121) This invention relates to a cooling tower and to its operation. In one of its aspects, the invention relates to the provision of a cooling tower having associated therewith means for detecting combustible material which has` undesirably leaked into the coolant, for example, water which is employed, whereby to give a signal or to render operative some other factor for safety of the personnel and the equipment. In another of its aspects, the invention relates to a method for preventing undesired continued leakage from within a cooling coil or zone of a fluid or liquid cooled therein by analyzing the coolant surrounding said coil or employed in said zone for any undesirably leaked quantities of said fluid' or liquid being cooled therein to obtain a signal or impulse which causes to function an emergency zone. In one of its more specific aspects, the invention relates to cooling towers and their operation to cool hydrocarbon vapors and liquids by analyzing cooling water or vapors associated therewith for any leaked hydrocarbon. In a further aspect of the invention, it relates to the prevention of growth of bacteria in cooling tower water 'by detecting hydrocarbon leaked thereinto from the coil over which said water is passed and removing the undesired hydrocarbon from the water Whenever it is present.

Cooling towers are often used for cooling liquids or gases by indirect contact whereby the fluid to be cooled passes through coils and the water falling down through the cooling tower passes over the surface of the coils which are located in the tower or is pumped to the coils which can be located elsewhere. These cooling coils can spring a leak and cause loss of valuable uid, such -as hydrocarbons. When the ilu-ids lost are combustible, there is often also created an explosive mixture in the air or an accumulation of a liquid' which will burn. In some cases, the fluids which have leaked have caught fire and the burning of the cooling tower has resulted.

Among the objects of the invention are to provide an emergency operation and apparatus for detecting a leak into coolant of material being indirectly cooled, e.g., a hydrocarbon vapor, and causing emergency action or operation to take place.

Other aspects, objects and the several advantages of the invention are apparent from this disclosure, the drawing and the appended claims.

The invention is especially adapted to cooling towers in which hydrocarbons are either condensed or cooled in the coils of the cooling tower. When leaks occur normally liquid hydrocarbons escape into the water which passes down into the reservoir of the cooling tower, these hydrocarbons may catch lire and burn the tower.

According to this invention, there is analyzed the cooling water or vapors in or associated with the cooling tower. Thus, in one embodiment of the invention, a small side stream of thel water being recirculated to the top of the tower is removed and' analyzed for materials which are being cooled within kthe coils of the tower. The analyzer can be connected to a controller which will shut down the pump which circulates the water from the reservoir to the top of the tower or it can only sound an alarm or do both. Or, a small stream of liquid from the surface of the reservoir of the cooling tower or a small stream of the gases passing up through the cooling tower is analyzed for iluids being cooled within the coils.

In one case, the hydrocarbon is cooled or condensed in cooler units that are located away from the `cooling tower, as in shell and tube exchangers on fractionator reux and other related services. The Water serving such coolers is pumped from the cooling tower basin, and through the shell and tube condensers Ilocated varying distances away. The water takes on a heat load and returns to the top of the cooling tower and is cooled in dropping through the tower into the pit. This is a continuous circulation system. In this process, if a hydrocarbon side tube is leaking at a pressure higher than the 40 or 50 p.s.i.g. of the water, the hydrocarbon will leak into the water, thus returning a water-hydrocarbon mixture to the tower. If the hydrocarbon is volatile, such as butane or propane, it will dissipate within the tower, thus setting up a condition of loss of product and a hazard for explosion, as mentioned. If the hydrocarbon is heavy or stable, it will drop down to the pit of the tower with the water. A small by-pass stream of the lreturn water is removed and introduced to a flash tank on which a liquid level is maintained. The flashed vapors are continuously analyzed by a hydrocarbon detector-indicator, and when vapors are present the detector sounds an alarm, or shuts down the pump or both, depending upon whether either or both is desired.

In another case, in which cooling is obtained by water passing over tube units set on piers directly inside the cooling tower over the pit or basin, when a tu'be leaks, the hydrocarbon will drop into pit water and iloat on top of the pit water. Since water is continuously drawn oi from the various pits, in order to keep the concentration of total solids down to a low iigure, any leaked hydrocarbon iiows out first, since the water is allowed to overflow into the continuous drain system. In this type of operation, the vapor analyzer is installed on an accumulator or yflash tank serving the continuous overflow drain system. Thus, any tube leaks actuate the continuous vapor indicator-recorder and set oif an alarm. Hazard and product loss is thus greatly minimized.

As will be understood by one skilled in the art, the invention is physical in character and has wide application to the signaling of undesired leakage into the cooling water of material being cooled. Thus, any organic compound which may be combustible or any other material being cooled, leakage of which into the cooling water or other medium being circulated in the cooling zone is undesired, and which compound or material has leaked into the cooling medium or water can be signaled for appropriate attention according to the present invention.

The drawing schematically shows a cooling tower with associated leak detecting means.

Referring now to the drawing, induced draft cooling tower 1 is made of sections 15, 1-6, and 17. Each section is 20 feet long, 40 feet vsn'de and 40 feet tall. Sections 15 and 16 are operated to cool the water used in heat exchanger 8. The water cooled in section 17 is used as cooling water for heat exchanger 2. Air at the rate of 7 million standard cubic feet per minute is drawn through each of the sections of the tower. Water -at the rate of 2334 g.p.rn. is pumped through heat exchanger 8 and water is pumped at the rate of 1166 -g.p.m. to the top of section 17. Butane at 65 p.s.i.g. and 129 F. is passed to heat exchanger 2 by way of pipe 3 and to heat exchanger 8 by way of pipe `14,. Water enters the top of the cooling tower at 100 F. and is withdrawn from the bottom of section at 80 F. The water withdrawn from the bottom of section 17 is at 100 F. Water at the rate of about 30 ccs. per minute is passed through rotometer 18 and into chamber 19 wherein it is lheated with coils 20 t0 within 2 or 3 degrees of the boiling point of water. Chamber 19 is 8 inches in diameter and 3 feet high. It is maintained about half full of water. The temperature of the water in chamber 19 is regulated by thermocouple 21 which is connected to a temperature recorder controller, not shown, W-hich actuates motor valve 22 controlling ow of heating medium in coil 20 to maintain a constant temperature in chamber 19. Liquid level controller 23 actuates motor valve 24 to maintain a constant liquid level in chamber 19. Air, under pressure, at the rate of ccs. per minute is passed through line 30. The air passes through an orifice 31 which is operatively connected to a rate of flow controller, not shown. The rate of ow controller is also connected to motor valve 32. Air is passed up through the water in chamber 19 to remove any vaporizable hydrocarbons present in the water. The gases from chamber 19 pass through line 26, heat exchanger 27 and into gas liquid separator 28. The condensed water from separator 28 passes through line 29, flow through which is controlled by valve 33 which in turn is controlled by liquid level recorder controller 34, and the uncondensed gases from separator 28 pass into analyzer 25. Analyzer 25 is a Mine Safety Appliance Company combustible gas alarm, described in MSA Catalog 6B, copyrighted 1951. The alarm 25 may be set to sound when the concentration of butane in the water passing into chamber 19 contains from one to two parts per million by weight of hydrocarbons. When desired, alarm 25 can be operatively connected to draw vapors from the bottom of section 17 of the cooling tower 1 through line 11 and analyze the uncondensible gases. An exhaust pump 35 is provided to draw vapors into and through alarm 25, as desired. If desired, a signal is arranged to be transmitted from element 25 by way of dashed lines 37 and 37 to pump 6 and/ or line 38 to shut down these pumps in the event of an emergency and though not shown, the same signal can be used to operate valves which will switch materials to be cooled in heat exchanger 2 and/or heat exchanger 8 to other heat exchangers for their continued cooling.

Reasonable variation and modification are possible within the scope of the foregoing disclosure, the drawing and the appended claims to the invention, the essence of which is that cooling medium in an indirect cooling zone is analyzed for leakage thereinto of material being cooled to obtain a signal or impulse which is relayed to an emergency zone which functions to prevent a fire or other undesirable occurrence.

I claim:

l. A method for operating a cooling coil being used to cool a combustible material, the coil being cooled by water from a cooling tower, which comprises analyzing the cooling water in an analyzing zone for traces of combustible material leaked from said coil to obtain an impulse which said analyzing zone is adapted to yield and automatically relaying said impulse to an emergency zone which functions to prevent further leakage by shutting down the cooling coil operation.

2. A method of operating a cooling water cooling tower used to cool water which is supplied to a cooling zone, the cooled water of which is employed to cool indirectly a combustible material, such as a hydrocarbon, which can leak from the cooling zone into the cooling water, which comprises removing at least a portion of the cooling water which may contain undesirably some hydrocarbon which has leaked into said water, passing said water and any leaked hydrocarbon associated therewith into a flashing zone, hashing hydrocarbon from said water in said ashing zone, and passing vapors produced in said flashing zone into a hydrocarbon vapor detecting zone adapted to produce a signal whenever said vapors contain in excess of a predetermined proportion of hydrocarbon.

3. A method according to claim 2 wherein water which is passed to said ashing zone is removed from the surface of the water `contained as a liquid within said water cooling tower.

4. A method of operating a cooling water cooling tower, the cooled water of which is employed to cool indirectly a combustible material, which comprises removing vapors from the cooling water, passing said vapors including any leaked combustible vapors associated therewith into a vapor detecting zone adapted to produce a signal whenever said vapors contain in excess of a predetermined proportion of vapor and automatically relaying said signal to activate an emergency zone which will operate to prevent further leakage upon receiving said signal.

5. A cooling means, means associated with said cooling means for indirectly cooling a combustible material, means for analyzing the coolant in said cooling means for any combustible material undesirably leaked thereinto, means for yielding an impulse when there is detection of leaked material in said coolant, means for automatically conveying said impulse to a zone which operates responsive to said impulse to prevent further leakage, said means for analyzing said coolant comprising in combination, a vessel, means for maintaining a liquid coolant level in said Vessel, means for maintaining a desired temperature in said vessel, means for introducing an entrainer medium into said vessel below the liquid level maintained therein, means for removing vapors from -above the liquid level in said vessel and means for analyzing said vapors removed from said vessel, and to yield said impulse whenever said vapors contain a dangerous concentration of combustiblervapors therein.

6. A water cooled cooling coil, a water cooling tower operatively associated with said coil, means for conveying cooled water from said tower to a cooling coil, means for contacting said water with said coil, means for analyzing said water to detect any material leaked from said coil into said water, means for yielding an impulse when there is detection of material leaked into said water, a pump for circulating water to the top of the cooling tower, means for automatically conveying said impulse to said pump so that it will be automatically shut down responsive to said impulse to prevent further circulation of the water to the top of the cooling tower.

7. A method for operating an externally cooled cooling zione in which there is being cooled a combustible material and from which combustible material due to leakage can contaminate the coolant which externally cools said cooling zone which comprises analyzing at least a portion of said coolant used to cool said cooling zone so as to obtain a signal whenever combustible material appears therein due to said leakage and automatically relaying said signal to cause shut-down of the operation of the cooling zone.

8. A method for avoiding accumulation of a combustible material which may cause a tire due to leakage thereof from an externally cooled cooling zone in which said combustible material is being cooled and from which it may leak into a coolant material-containing zone, the improvement which comprises analyzing at least a portion of coolant in said zone in a manner so as to obtain `a signal whenever undesired combustible material appears in said coolant material and automatically relaying said signal to activate an emergency zone which will function automatically upon receiving said signal to prevent further leakage of said combustible material.

References Cited in the le of this patent UNITED STATES PATENTS 2,658,728 Evans Nov. 10, 1953

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