US3130557A - Cooling tower control means - Google Patents

Description

April 23, 1964 Filed May 23, 1962 V A105 1. mafia/v ATTORNEYS United States Patent Ofiice 3,130,557 Patented Apr. 28, 1964 3,139,557 CGGLING TDWER OJNTRGL Alden Irving ltdcl arian, 691 Borian Road, Westfield, Filed May 23, 1952, Ser. No. 197,054

3 Qlaims. ('31. 62-471) The present invention relates to cooling towers for cooling water by evaporating a portion thereof and more particularly to an arrangement which utilizes the liquid distributing element of the cooling tower as a sprinkler system to extinguish fires therein during shutdown periods.

in recent years the development of air conditioning for buildings has materially increased the number of cooling towers in use. Cooling towers used for air conditioning, or with other systems requiring cooling water, are usually located on the roof of the building which they service. Conventional cooling towers are in the form of a line having an outer shell through which air fiows upwardly and liquid distributing means for delivering water onto a packing or fill for gravity flow therethrough. The flow of air may be induced by a chimney effect, but usually a fan is provided for circulating air through the shell. The water delivered to the packing or fill tricldes and drips from one surface onto another as it flows by gravity to increase the area of surface contact between the liquid and air.

Different types of material are used for the shell and packing of a cooling tower. Many cooling towers, however, have a wooden shell and packing such as, for example, cypress, and the packing may be in the form of slats placed in successive layers, one over the other, with the slats in successive layers arranged at right angles to each other. Packing of other materials such as metal and asbestos cement are in use, but have disadvantages which generally render them unsatisfactory. For example, corrugted metal packing sheets have an excessive rate of decomposition due to corrosion and other chemical reactions. Sheets of asbestos cement are expensive to manufacture and have an excessive weight. Still another type of packing which is being used extensively is a corrugated paper impregnated with a resin.

With the increased use of air conditioning in buildings it has been found that more and more fires have occurred in cooling towers during the winter months while they are out of service. During the winter the cooling tower is usually drained of all water to prevent freezing even though it might be desirable to operate the cooling tower during warm spells. As a result of the shutdown during the winter, the cooling tower dries out and especially so when the packing is composed of wood.

Sparks from chimneys and smoke stacks apparently fall into the dry packing and start a fire. A packing of spaced wooden slats provides an ideal arrangement to support combustion so that they usually burn very quickly. The liquid distributing system for the tower is of no help during shutdown as conventional controls will not supply water in case of fire and when such a fire is discovered, it is usually too late to put it out. As a result, the cooling tower usually burns completely and produces a total loss.

One of the objects of the present invention is to utilize the cooling tower itself as a sprinkler system to extinguish any fire that may occur in the packing when the tower is out of service.

Another object is to provide a cooling tower adapted to be drained during the winter to prevent freezing and immediately operable upon occurence of a fire to sprinkle water on the packing.

Another object is to provide a fire extinguishing system for cooling tower which is automatic in operation upon occurrence of a fire even at freezing temperatures.

Still another object is to provide a fire extinguishing system for a cooling tower which is of an extremely simple construction, requiring a minimum of parts in addition to the conventional elements of a cooling tower, economical to install and one which is reliable in operation.

These and other objects will become more apparent rom the following description and drawings in which like reference characters denote like parts throughout the several views. it is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not a definition of the limits of the the invention, reference being had for this purpose to the appended claims.

in the drawing:

FlGURE 1 is a diagrammatic view of an air conditioning system and cooling tower for a building which incorporates the novel features of the present invention to automatically operate the liquid distributing system of the tower as a fire extinguisher in case of fire.

Referring now to the drawing, the present invention is shown applied to an air conditioning system for a building having a root 2 on which a cooling tower 3 is mounted for supplying cooling water to the system. Partitions 4 and 5 are illustrated for the purpose of showing that the space in the building may be divided into different rooms or areas having different air conditioning requirements. For example, certain areas 6 and 7 may require cooling while area 8 may require heating.

The air conditioning system as illustrated is generally similar to that described and claimed in my prior U.S. Patent 2,796,740, issued June 25, 1957, and entitled Air Conditioning System, and 2,984,458, issued May 16, 1961, and entitled Air Conditioning. Sufice it to state herein that the system comprises a plurality of refrigeration units id, 11 and 12 arranged in series as described and claimed in my pat nts, Numbers 2,796,740 and 2,934,458. Each refrigeration unit comprises a compressor 16a, 11a and 12a, a condenser 10b, 11b and 12b and evaporator 10c, 11c and 120, respectively. Each compressor 10a, 11a and 12a is connected to deliver gas at high pressure to its respective condenser 10b, 11b and 12b where the gas refrigerant is liquified by the removal of the latent heat of vaporization at a relatively high temperature. The liquid refrigerant in each unit then flows from its condenser 31%, 11b and 12b to its corresponding evaporator lire, 11c and through a connection including an expansion valve 19d, 11d and 12d, respectively. The expansion valves 10d, 11d and 12d control the flow of liquid refrigerant to the respective evaporators 10c, 11c and 120 as the compressors 10a, 11a and 12a withdraw refrigerant vapor from the evaporators at low pressure to produce an evaporation of refrigerant and absorption of heat at a relatively low temperature. The heat absorbed by the evaporators at relatively low temperature is transferred from the condensers 10b, 11b and 12b to a cooling medium, such as water, which is delivered to the cooling tower 3 where the heat is dissipated to the atmosphere outside the building by evaporating part of the water. At least one of the condensers 10b, 11b and 12b is a double condenser having two separate paths of flow therethrough for a heat transfer medium such as cooling tower water or a heating medium. In the illustrated embodiment the condensers 11b and 12b of both units 11 and 12 are the double type.

A closed circuit 13 for a conditioning medium connects the evaporators 10c, 11c and 120 of the refrigeration units 19, 11 and 12 in series and the circuit includes a pump 14 for circulating the conditioning medium through the circuit. The closed circuit 13 has one branch 15 beyond the pump 14 which flows through the evaporators 19c, 11c and 12c to provide a chilled water line and a branch 16 flowing through one path of the double condensers 11b and 12b to provide a hot water line. The chilled water branch line 15 is connected to one or a plurality of heat transfer coils 17, 18 and 19, and a return line 20 connects all of the heat transfer coils to the pump 14. The hot water branch line 16 also is connected to each of the heat transfer coils 17, and

19 and the delivery of chilled or hot heat transfer medium is controlled by a valve 21, 22 and 23 for each of the coils, respectively, in accordance with requirements. Thus, the refrigeration system comprises a chilled water line 15, a hot water line 16 and a common return line 29 known in the art as applicants three-pipe system for heating and cooling. The heat exchange medium may comprise water, but preferably is an antifreeze solution containing, for example, ethylene glycol.

The condensers 19b, 11b and 12b preferably are of the so-called shell and tube type having a shell 24, spaced tube sheets 25 and 26, headers 2'7 and 28 at opposite ends of the tube sheets with heat transfer tubes 29 extending between the tube sheets and connecting the headers at opposite ends. In addition, the double condensers 11b and 12b have partitions 3t and 31 between the headers 27 and 28 and tube sheets 25 and as, respectively, to divide the condensers into the two paths of flow. As shown in the unit 11 hot refrigerant vapor is delivered to the shell 24 in the space between the tube sheets 25 and 26 and around the exterior of the tubes 29 and the heat of vaporization is transferred through the tube walls to the conditioning medium flowing in a path through one nest of condenser tubes in the hot water branch line 16, or to a cooling liquid flowing therethrough in an open cooling water circuit 35 as next described and including the other nest of tubes.

Open cooling water circuit 35 connects the cooling tower 3 and condensers 16b, 11b and 12b and includes a pump 36 for circulating cooling water theretnrough. Circuit 35 connects the sump 39 of the cooling tower 3 to one end of condenser 19b, and the circuit has branches 35a and 35b with valves 37 and 33 in the respective branches to adapt the cooling water to flow through the condensers in series or in parallel arrangement. As will be observed in the drawing, water in the open cooling water circuit flows in a path through the upper nest of tubes 29 in the condensers llb and 12b. The pump 36 is shown at the outlet end of condenser 12b and connected to deliver water to be cooled to the top of the cooling tower 3 to complete the circuit.

Cooling tower 3 comprises a shell 4t? having a packing 41 therein. Both the shell 48 and packing 41 may be composed of wood, such as cypress which is particularly resistant to rot, and the packing comprises slats 42 mounted in spaced parallel relation in successive layers with adjacent layers arranged at right angles to each other. Overlying the packing 41 is a liquid distributor 43 of any conventional form such as spray nozzles, troughs, and the like, used in cooling towers and shown, for purposes of illustration, as spray nozzles 44 for spraying the water to be cooled onto the top of the packing 41. Openings 45 are provided in the sides of the shell 40 adjacent the bottom of the tower 3 and a fan 46 driven by a motor 47 is provided at the top of the tower for circulating air upwardly through the packing 41 in a direction countercurrent to the direction of gravity flow cooling water to provide an extended are for gas and liquid contact. As thus far described, the air conditioning system including the cooling tower 3 is substantially identical with the system disclosed in my prior Patent 2,796,740, referred to above. It is to be understood, however, that heat transfer coils 17, 18 and 19 may provide conditioned air for distribution throughout an area, or may provide primary air for peripheral air induction or fan coil units for particular areas or rooms.

In accordance with the present invention, a novel combination and arrangement of elements is provided for utilizing the liquid circuit and distributing means of the cooling tower as a fire extinguishing system for the tower when the latter is out of service during the Winter months, or shut down for any reason. The arrangement provides a control for operating the pump 36 in the Open cooling liquid circuit in a conventional manner during summer months, or operating the pump 36 after the tower has been drained to provide a fire preventing sprinkler system. To this end, a tank 5%) is provided in the building below the roof 2 and cooling tower 3 and into which the water from the cooling tower 3 may be drained during winter months to prevent freezing. Thus, the water tank 5t provides an additional sump for the cooling tower to adapt it to be operated on any warm day during the winter when cooling water may be required without danger of a freeze up, or as a source of Water for extinguishing a fire in the cooling tower at any time.

Tank 50 is connected in a branch 350 of the open cooling water circuit and has a valve 51 for opening the branch circuit to drain water from the tower and close the branch circuit to cause the cooling water to bypass the tank 5% in a parallel branch 35d. During normal operation the valve 51 is closed and pump 36 is controlled, in the illustrated embodiment by a thermostatically operated double-pole switch 52 responsive to the temperature of the heat transfer medium in the hot Water branch 16 of the closed circuit 13 leaving the condenser 12b. The switch 52 has a contact 52a connected to one side of the power line P1 and a movable contact 52b for engagement therewith which, in turn, is connected to the motor winding of the pump 36. The opposite end of the pump winding is connected to the opposite side of the power line P2. Switch 52 also has a second contact 520 and movable pole 52d connected through a line 53 to the motor 47 for operating the fan 46. The opposite end of the fan motor is connected by a line 54 to the other side of the power line P2. The two movable pole contacts 52b and 52d of the thermostatic switch 52 are operated simultaneously by a bellows type motor 55 of a thermostat having a temperature responsive bulb 56 in thermal contact with the hot water branch 16 from the condenser 12b. Thus, when the temperature of the heat transfer medium leaving the condenser 12b exceeds a predetermined temperature, for example, 105 F., thermostatic switch 52 closes contacts 52a, 52b and 52c, 52d to initiate operation of the pump 36 and fan 46. Pump 36 then circulates cooling water through the condensers 10b, 11b and 12b to reduce the temperature in the condensers and delivers the water to the cooling tower 3 where the heat absorbed in the condensers is dissipated to the atmosphere to cool the water for recirculation through the condensers. As soon as the temperature of the air conditioning medium decreases to a fixed value of, for example, F., the thermostatic switch 52 is again actuated to discontinue operation of the pump 36 and cooling tower 3. It will be understood, however, that any other suitable control, either manual or automatic, can be used to start and stop the pump and fan.

The outlet of branch 350 from tank 50 is in open communication with branch 35d so that water from sump 39 of cooling tower 3 can back up into the tank between cycles of operation. During operation the water will be retained in the packing 41. Make-up water is supplied to the tank 5% from a pressure supply line 57 and valve 58 controlled by a float 59. Water will be maintained at some level L1 during operation and at another level L2 when valve 51 is opened to dump the water from sump 37 to shut down the cooling tower.

In addition to thermostatic switch 52, the pump 36 is controlled by a second thermostatic switch 60 having a contact 60a connected to the power line P1, a movable contact tld and a line 63 connecting the movable contact to the motor of the pump. Switch 64) is operated by a bellows type motor 64 having a plurality of thermal sensitive bulbs 65 arranged in different areas of the packing 41 of the Cooling tower 3. It will be understood that the bellows 64 and bulbs 65 contain a volatile liquid which will vaporize at a temperature, for example, 150 F and produce a pressure suflicient to close the switch 60. One form of the invention having now been described in detail, the mode of operation is next described.

At all times when the atmospheric temperature is above freezing and the cooling tower 3 is in operation, the valve 51 in the branch circuit 350 from the cooling tower is closed so that the cooling water flows through the branch circuit 35d. When the air conditioning system is in operation, pump 14 circulates conditioned medium through the evaporators c, 11c and 120 of the refrigeration units It), 11 and 12 to provide chilled water in the branch circuit 15 and in a path through condensers 11b and 12b to provide hot water in Lhe branch 16. Valves 21, 22 and 23 control the flow of hot water or chilled water to the coils 17, 18 or 19 as required, and the conditioning medium flows through the return line 20 to the pump 14 to complete the circuit. When the load in the closed circuit 13 becomes a preponderantly cooling load with only a limited circulation in the hot water branch through the condenser 11b and 12!), the temperature of medium in the hot water branch 16 may increase above an efficient operating temperature which is sensed by the bulb 55 and operating through the bellows 55 closes the thermostatic switch 52. Closure of the switch contacts 52a, 52b and 52c, 52d completes an electric ci cuit through the pump motor 36 and fan motor 47 to circulate water and air through the cooling tower 3. The flow of cooling water from the sump 37 of the cooling tower 3 through the branch circuit 35b and condensers 10b, 11b and 12b removes the heat of vaporization from the refrigerant to condense it to a liquid and reduces the temperature and pressure therein. The cooling water is then returned to the cooling tower 3 by the pump 36 where it is again cooled by evaporating a part of the water. Make-up water is supplied to the circuit through the supply line 57 which maintains a predetermined level L1 in the tank 59. Thus, the air conditioning system and cooling tower 3 operate to remove heat from the interior of the building and discharge the heat to the atmosphere through the cooling tower.

During the winter time when the temperature is below freezing, or at any time when the cooling tower is to be shut down, the valve 51 is opened which drains water from the tower 3 into tank 50 to prevent a freeze-up. The cooling tower 3, however, may be operated whenever cooling water is required by merely initiating opera tion of the pump 36 to deliver cooling water from tank 54) to the cooling tower and which flows from the cooling tower hack into the tank. Such operation of the cooling tower 3 may be desired on particularly warm days in January when operation of the air conditioning system is necessary to maintain comfort conditions.

Assuming, however, for purposes of description that the cooling tower 3 has been shut down for a period of time and a spark from a chimney or stack in the neighborhood has ignited the dried out wooden packing in the tower 3, the initial burning of the packing would so increase the temperature of the sensing bulb 65 closest to the fire as to close the switch 60. Closure of the switch 60 initiates operation of the pump 36 which then delivers water from the tank 50 to the liquid distributor 43 overlying the packing and sprays the water on the packing to extinguish the flame. During operation of the pump 36, water is continuously supplied to the tank 50 through the supply line 57 as controlled by the float 59 so that sufiicient water will always be available. As soon as the fire has been extinguished, the temperature decreases to open switch 66 and operation of the pump is discontinued. Thus, the elements of the open cooling water circuit are used as a sprinkler system for extinguishing fires.

It will now be observed that the present invention utilizes the cooling tower itself as a sprinkler system to extinguish any fires that may occur in the cooling tower during shut down periods. It will further be observed that the present invention provides a control system for draining a cooling tower during the winter months to prevent freezing which adapts the cooling tower to be immediately operated to provide cooling water or to extinguish fires. It will still further be observed that the present invention provides an extremely simple construction to automatically operate a cooling tower as a fire extinguishing sprinkler system and one which is reliable in operation.

While a single embodiment of the invention is herein illustrated and described it will be understood that changes may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect the invention is defined by the following claims.

I claim:

1. In a cooling tower of the type containing a packing of inflammable material onto which water is delivered to trickle therethrough by gravity and through which air is circulated to provide an extended surface area for air and liquid contact, the combination with said cooling tower of a tank in an enclosure below said tower and connected to the bottom thereof to receive water therefrom, a pump for circulating water in a circuit including the tank and cooling tower, a first means for initiating operation of the pump to deliver water from the tank onto the packing to operate the cooling tower to cool water, and a second means responsive to the temperature of the packing in the cooling tower for initiating operation of the pump in case of fire to deliver water from the tank on top of the packing.

2. Apparatus for transferring heat from the interior to the exterior of a building comprising a cooling tower for the building having a packing which is apt to ignite and burn during shut down periods, liquid distributing means overlying the packing to deliver water onto the top thereof which trickles downwardly through the packing by gravity, means for circulating air through the packing to provide an extended area for gas and liquid contact, a pump for delivering water to be cooled to the cooling tower, a first means for controlling operation of the pump to supply water to be cooled onto the top of the packing, and a second means responsive to the temperature of the packing in the cooling tower for initiating operation of the pump in case of fire to deliver water through the liquid distributing means onto the top of the packing.

3. in an air conditioning system for a building having a roof, a cooling tower on the roof of the building and having an inflammable packing, a tank in the building below the cooling tower, at least one refrigeration unit having a condenser, an evaporator and heat exchanger, a closed circuit for conditioning medium including a pump for circulating the medium through the evaporator and heat exchanger, an open circuit for cooling water including a pump for circulating water through the condenser and cooling tower, means connecting said tank in said open circuit to store water therein and deliver water therefrom, a first means for initiating operation of the pump in the open circuit for circulating cooling water through the condenser and cooling tower, and second means responsive to the temperature in the packing for automati cally initiating operation of the pump in the open cooling water circuit to deliver water from the tank to the cooling tower to extinguish any fire ignited in the packing.

4. An air conditioning system for a building in accordance with claim 3 in which the cooling tower has a liquid distributing means overlying the packing to deliver water thereto for fiow therethrough by gravity and a fan for circulating air through the packing, the control means responsive to a condition afiected by the air conditioner having a thermostatic switch responsive to the temperature of the water leaving the condenser, said control means operating the pump and fan simultaneously, and

second means responsive to the temperature of the packing having a thermostatic switch connected to operate the pump independently of the fan. 7

5. An air conditioning system for a building in accordance with claim 3 in which the open circuit for cooling Water has a branch including a valve for connecting the cooling tower to the tank when the valve is open and a branch bypassing the tank when the valve is closed. 6. An air conditioning system in accordance with claim 5 in which a water supply line is connected to the tank, and a float operated valve in the tank for controlling the flow of water from the liquid supply line to the tank to provide make-up water for the cooling tower and a source of water when the open circuit is operating as a fire extinguishing system.

7. An air conditioning system for a building in accordance with claim 3 in which the closed circuit for conditioning medium has a branch for delivering Water through the evaporator and a branch for delivering water in a path through the condenser, control means for delivering chilled and hot water in the respective branches to the heat exchanger, and the means responsive to the temperature affected by the air conditioning system is a thermostatic switch responsive to the temperature of the water leaving the condenser.

8. An air conditioning system for a building in accordance with claim 3 in which a plurality of refrigeration units are provided, each of the refrigeration units having an evaporator and a condenser, a plurality of heat exchangers, at least one of the condensers having separate paths of flow for cooling medium therethrough, the closed circuit having a branch for circulating a conditioning medium through the evaporator of the plurality of refrigera tion units in series and a branch for circulating medium through at least one of the paths of flow through the condenser, a pump for pumping conditioning medium through said branches of the closed circuit to provide chilled water in one branch and hot water in the other branch, a control valve for each heat exchanger for delivering condi-' tioning medium from the separate branches to the heat exchangers as required, and the thermostatic switch for controlling the pump in the open cooling water circuit being operable responsive to the temperature of the Water leaving the condenser in the hot Water branch of the closed circuit.

Kiehl Oct. 19, 1893 Lau Bach Mar. 20, 1951

Claims (1)

1. IN A COOLING TOWER OF THE TYPE CONTAINING A PACKING OF INFLAMMABLE MATERIAL ONTO WHICH WATER IS DELIVERED TO TRICKLE THERETHROUGH BY GRAVITY AND THROUGH WHICH AIR IS CIRCULATED TO PROVIDE AN EXTENDED SURFACE AREA FOR AIR AND LIQUID CONTACT, THE COMBINATION WITH SAID COOLING TOWER OF A TANK IN AN ENCLOSURE BELOW SAID TOWER AND CONNECTED TO THE BOTTOM THEREOF TO RECEIVE WATER THEREFROM, A PUMP FOR CIRCULATING WATER IN A CIRCUIT INCLUDING THE TANK AND COOLING TOWER, A FIRST MEANS FOR INITIATING OPERATION OF THE PUMP TO DELIVER WATER FROM THE TANK ONTO THE PACKING TO OPERATE THE COOLING TOWER TO COOL WATER, AND A SECOND MEANS RESPONSIVE TO THE TEMPERATURE OF THE PACKING IN THE COOLING TOWER FOR INITIATING OPERATION OF THE PUMP IN CASE OF FIRE TO DELIVER WATER FROM THE TANK ON TOP OF THE PACKING.

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