US2055543A - Safety device for refrigerating systems - Google Patents

Description

29, 1936. 1 KlRGAN 2,055,543

SAFETY DEVICE FOR REFRIGERATING SYSTEMS Filed Dec. 19, 1934 INVENTOR.

Jog, [fir am. BY r CQ H15' ATTORNEY Patented Sept. 29, 1936 lPATENT OFFICE SAFETY DEVICE Fon REFRIGERATING sYsTEMs John Kirgan, Easton, Pa., assignor to Ingersoll- Rand Company, Jersey City, N. J., a corporation of New Jersey Application December 19, 1934, Serial No. 758,182 3 claims'. (01. 62-152) 'Ihis invention is an improvement in safety devices, especially devices to insure the safe operation of machines in refrigerating systems which act to chill a quantity of water to be after- 5 wards used for cooling purposes.

In refrigeratingrsystems of this type, known as water-vapor refrigeratng apparatus, the cooling effect is brought about by converting a part of the water into vapor and lowering the temperalo ture of the main body of the water by the loss of heat which is extracted therefrom when said vapor is formed. To this' end the water is intro-l duced into a -vessel or evaporator containing a high vacuum, and the Water vapor formed is withl drawn by an evacuating member of sufficiently high capacity and transferred to a condenser where it is liquefied. To remove the water vapor l from the evaporator a centrifugal compressor has been found to have many advantages,` but such a compressor, to be of moderate dimensions and yet have the required capacity, must be operated at high speed, andthe parts are therefore of comparativelylight construction. Hence it is important that nothing but water vapor be a1- 25 lowed to enter the housng of the compressor, be-

cause if water in liquid form is admitted and gets into the path of. the fast moving vanes thereof great damage such as the bending or breaking of the varies will ensue before this condition can be 3@ remedied.

` An object of my invention is to safe-guard the centrifugal compressor and prevent the admission thereto of water from the evaporator when the compressor is running. 'I'his is accomplished I Y of water in liquid form to the compressor housing would begin, .and at once slow down and quicky ly stop the latter. Hence, even if some water 45 does enter the compressor, the rapid diminution.

in the speed thereof will 'effectually prevent any harmful consequences.

With these and other objects and advantages in. view, the invention consists in the novel feao tures set forth in the description, and pointed out '1in the claims. But the disclosure is illustrative l only and changesmay be made without exceeding the scope and broad meanings of the terms in which the appended claims are expressed.

55 The drawing shows in outline a centrifugalv compressor water-vapor refrigerating system with a safety device according to this invention.

The invention comprises an evaporator I to which the liquid refrigerant, such as water, is l admitted by way of pipe 2. This pipe comprises 5 a section which is disposed horizontally near the top of the evaporator and is there provided with a number of openings to enable the water to issue therefrom in the form of sprays or jets. At the top of the evaporator is an outlet 3 leading into 10 the housing 4 of a centrifugal compressor', which extracts water vapor from the evaporator and delivers it to a condenser (not shown) to be liquelied. This compressor is driven by a motor such as an electric motor 5 connected to the rotor of 15 lthe compressor by step-up gearing indicated in outline by the numeral 6. The compressor may embrace several stages, each with a set of revolving vanes on the compressor shaft operated by the motor 5'. To run the motor, electric current is supplied from mains 'I to suitable connections including an overload switch or circuit-breaker 8. The revolution of the rotor (not shown) in the compressor Il at`the start of the operation withdraws the .gaseous an/d vapor contents of the evaporator l and creates therein a vacuum so that when water is admitted by the pipe 2 and sprayed downwardly into the evaporator I, some ofl it is transformed into vapor at onceand this vapor is exhausted by the compressor or rotary evacuator through the opening 3. The latent heat of vaporization that is absorbed by the part of the water which is vaporized, will lower the tempera- Ature of the rest of the water several degrees. The

main body of the water remains liquid and flows out through an outlet opening Q in the bottom of the evaporator to a discharge pipe I0 connected through a pump I I to a delivery conduit which is 4supply pipe or conduit 2 within the evaporator I is a valve I3 having an arm extending outside of the pipe and controlled by a float lever I4,v When the level of the water rises in the evaporator the float lever I4 tends to close the valve I3, and to open this ,valve when the water level sinks; Thus the admission of the Water is regulated. 50 Owing to the fact that the pressure in the evaporator I is quite low the chilled liquid which collects on the bottom of the evaporator must be forcibly removed by the pump II. VSo long as the o pump Il continues working or the valve I3 does^55 not get out of order, the water on the bottom oi the evaporator does not become very deep and there is no risk of any of it reaching the top and passing through the outlet 3 into the housing 4 of the compressor. If, however, the pump fails to Work or if the valve I3 gets out of order, the evaporator I may ll up with water, some of which will then enter the compressor, and in the compressor housing the rotating vanes of the compressor will collide with same. `To prevent Such an eventuality the top of the evaporator carries a pipe I5 projecting downward into the evaporator, and carrying at its inner end-a relief valve l@ controlled by a oat arm I'I. Normally this iioat will not be raised, but will hang in such a position as to close the valve Iii. The upper or outer end of the pipe I5 opens through the bottom of an outside receptacle I3 which is on the top of the evaporator and normally contains enough water to form a seal for the valve I6. The compressor l will have water or other suitable liquid seals at 'the bearings of the drive shaft of the compressor,

so that the atmospheric air can not enter this housing around the drive shaft at its ends. Water or other liquid owing through these seals, or coming Afrom any other source, can be Vdischarged by way of a pipe I9 into the receptacle I8 and it is withdrawn from the receptacle I8 by pipe 2il. Hence the receptacle .I8 never overflows. f

With this construction if the evaporator I by any mischance ever lls with water, the float lll will be lifted to open the valve i6 before any of the water can rise up to the compressor inlet 3, and as soon as the valve I6 opens the water in the vessel I8 quickly drains into the evaporator and enough air is then admitted through the inlet passage in the pipe I5 to destroyV the vacuum therein. The admission of air, which is considerably heavier than water vapor, overloads the compressor, and the speed of operation drops at once, so that even if the water in the evaporator rises and some of it gets into the compressor, no damage will result. The overloading of the compresser and its motor causes the switch to break the supply circuit of the motor, and then in a moment or two, the compressor entirely stops.

After the compressor ceases to run, Water might of course continue to be discharged from the pipe 2 andrise in the evaporator I until it passes up through the outlet 3 into the compressor housing. As the vanes' are now motionless, no ill eects will be produced, but before the system is again started, the water level has to be lowered in the evaporator I and all the liquid cleared out of the compressor housing.

With this construction the system is safeguarded and all risk to the movable parts of the compressor is obviated. The arrangement is very simple and adapted to work instantly to give the desired result Whenever an emergency arises.

If the liquid ever gets high enough to open the valve I6, to admit air, overload of the motor occurs at once and the motor is cut out. The density of the air acts as a brake and slows down the rotor of the compressor to a speed which will not wreck or even damage the compressor should Water enter the housing thereof.

I claimrvl. The combination of an evaporator having connections to admit and discharge a liquid refrigv erant. an evacuator to withdraw vapor of the reirigerant formed in the evaporatorfmeansfor supplying energy to operate the evacuator, said means comprising a cut-oi device responsive to overload, and means controlled by conditions in. the

iol

evaporator to bring about overloading of the evacuator and the energy-supplying means to cause actuation of said cut-off device and thereby render the evacuator inoperative. A

2. The combination of an evaporator having connections to admit and discharge a liquid refrigerant, means normally acting to maintain constant refrigerant level in the evaporator, an evacuator to Withdraw vapor of the refrigerant formed in the evaporator, means for supplying energy to operate the evacuator, said meanscomprising a cut-0H device responsive to overload, and means arranged to be actuated when the rst-named means fails to operate to bring about overloading of the evacuator and the energy-supplying means and cause actuation of said cut-oi device to stop the operation of the evacuator.

3. The combination of a chamber having a liquid inlet and outlet, a float-actuated valve controlling the inlet and normally acting to maintain the liquid in the chamber at constant level, an evacuator creating vacuum in the chamber and removing vapor therefrom, means including a device responsive to overload and supplying energy to actuate the evacuator, normally-inoperative means arranged to operate at abnormally high liquid level in the chamber to admit a medium, heavier than said vapor to the evacuator, the

medium upon admission acting to overload the evacuator and device to cut oi the supply of energy and render the evacuator inoperative, and means providing a liquid seal for the normally-inoperative means; i

. JOHN KIRGAN.

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