US1041505A - Centrifugal compressor. - Google Patents

Description

S. A. MOSS.

GENTRIFUGAL OUMPRESSOR.

APPLICATION FILED MAB. 5, 190a.

Patented Oct. 15, 1912.

2 SHEETS-SHEET 1.

Inventor: nford 0Q 055 S. A. MOSS.

GENTRIFUGAL COMPRESSOR.

APPLICATION FILED MAR. 5, 1908.

1,041,505., 1 I Patented 001. 15, 1912.

2 SHEETS-SHEET Z.

Fig.2.

5 E z 16 2 15 I4 I llll O 7 2'5 KSQ I Witnesses: Inventor:

' Sanford.|\/Ioss,-

UNITED STAEN SANFORD A. MOSS, OF LYNN, MASSACHUSETTS, ASS-IGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL COMPRESSOR.

Specification of Letters Patent.

, Patented Oct. 15,i912.

Application filed March 5, 1908. Serial No. 419,278.

.Lynn, county of Essex, State of Massachusetts, haye invented certain new and useful Improvements in- Centrifugal Compres= sors, of which theifollowingis a specification. I

When the ordinary "reciprocating compressor is employed to supply air to a blast furnace or cupola and a choke occurs some- Where in the air passages which reduces the air openings, the pressure automatically increases or buildsup until the choke is removed. This is due to the fact that the piston of the compressor displaces a given volume of air .on each stroke and is moving at constant speed. The centrifugal compressor has many important advantages over the reciprocating compressor for such work but it has this objection, namely, that if driven at constant speed by a suitable prime mover it will give practically constant pressure under all circumstances. In

other words, if the cupola chokes up, the

compressor will supply less air but at the same constant pressure, whereas as above pointed out, an increased pressure is necessary to overcome the choke or obstruction.

My invention has for its object the overcoming of the objection above referred to by so arranging, constructing and operating the apparatus that .just as soon as the amount of air delivered by the centrifugal compressor and consequently the load on the prime mover driving said compressor decreases owing to a'choke in the cupola or other apparatus, the speed of the compressor and of its driving motor will, because of the unchanged or constant supply of energy to the driving motor, automatically increase until the air pressure is increased sufliciently due to said increase in speed to overcome the choke or obstruction, after which the pressure and speed will decrease and return to their normal conditions. Should a predetermined increase of pressure fail to remove the choke, provision is made for preventing further increase in speed above a desired maximum by controlling the supply compressor.

pressure at said speed for all loads, that is for all quantities of fluid discharged by the The compressor illustrated is designed to su ply 7000 cubic feet of free air per second at a pressure of .88 pounds per square inch under normal conditions. The quantity and pressure of the air or other elastic fluid delivered can be changed to meet difierent normal conditions by suitably changing the parts and driving the impeller ofthe compressor at the proper speed.

Mounted on the same shaft with the impeller of the compressor, or on a different shaft and connected thereto, is the moving element of a driving motor. As an illustration of amotor I have shown a steam turbine siiice it'is particularly Well adapted for the purpose on account of its simplicity,

economy of operation and relatively high speed, but the invention is not necessarilyv limited thereto in all particulars.

The

turbine is provided with one or more'noz- -zles or other fluid discharging devices to admit the required amount of steam to drive the bucket wheel and the impeller at such speed as will cause the latter under normal conditions to deliver the'desired quantity of air at the predetermined pressure. Theturbine is provided with a governor which under normal conditions of operation and V to the volume. Hence when the volume decreases the pressure increases. To state the matter in another way, if the cupola chokes, the load on the compressor or in other words, the quantity of air delivered by the compressor, decreases while the speed of its lmpeller increases because the input. of energy in the form of steam supplied to the turbine remains the same and the load on the turbine is less. Hence the pressure of the discharged air will be increased due to the increased speed of the impeller. This increase of speed ordinarily continues until the increasing pressure of the air overcomes the resistance to its passage. If, however,

the resistance is not overcome when a predetermined pressure is produced the governor will become active at some corresponding predetermined abnormal speed and prevent further increase of speed and pressure. p

The governor may be made to act in the manner above described in a variety of ways. As an example, one or more stops may be .provided which hold the weights out away from the shaft axis and in such a positi on that they are inoperative, in so far as their effect on the controlling valve is concerned, until the speed of the bucket wheelexceeds the predetermined limit after which they move the controlling valve toward its seat in the usual way until a balance is again effected between the steam input and the output of compressed air. This relation continues until the choke in the cupola is removed and the normal amount'of air is discharged by the compressor, when the governor weights return to their usual position against the stop or stops. Itnwill be seen that the governor has no control so longas the speed does not rise above said predetermined value, the full steam admission satisfying 'the ordinary operating requirements of the compressor, but it has control when the conditions beyond the compressor become abnormal to the extent described. I

- A main valve may be provided in the steam supply pipe of the turbine to reduce the initial pressure whereby the normal operating conditions of the apparatus may be changed and this without modifying the construction or relation of the arts.

In the accompanying drawings which illustrate one of the embodiments of my invention, Figure 1 shows a turbine-driven centrifugal compressor connected to a eupola; and Fig. 2 is a view of the turbine with certain parts broken away.

1 indicates a centrifugal compressor which is designed to give practically constant pressure for a given speed atall loads or quantities of air'delivered and is operated at. different speeds and pressures under the conditions above described. It is providedwith an inlet 2 through which air is supplied to the interior. of the compressor case mg from any desirable source and with an outlet 3 which is connected by a conduit 4 with a cupola or other apparatus 5 designed toreceive air. Mounted on the mainshaft 6 is an impeller 7 of any suitable construction which in the form illustrated in the drawing receives through the openings 7 adjacent the shaft 6 an delivered to the interior of the'casing by the inlet 2. Surrounding the impeller is an annulus 8 containing vanes 9 which convert the velocity of the air discharged by the impeller into pressure before discharging it into the outlet. The shaft is supported by bearings 10 and 11 of suitable construction. Mounted on one-end of the main shaft for driving it is a turbine bucket wheel 12, Fig. 2. The

turbine is provided with a casing 13 that is .15 or other device for discharging fluid to the wheel buckets. Situated in front of the valve chest 16 is a second valve chest 18 containing an emergency valve 19 which shuts off the steam supply in case of an emergency such as an excessive and dangerous increase of speed due to the failure of the main governor to operate. This valve 19 may be actuated by any well known form of emergency governing device which is brought into active operation by a certain speed greater than that normally permitted by the main governor. Steam is admitted to the chest 18 by aconduit 20 containing a manually operated throttle valve 21. On the end of the main shaft 6 is a centrifugal governor comprising weight-arms 22 whose movements are opposed by the coiled extension spring 23. The tension on this spring is such that it prevents the governor weights 30 from acting so long as the speed of the motor is normal or below normal and the quantity and pressure of the'air delivered by the compressor are normal. Said spring. also opposes the action of the weights during the increase in speed and pressure permitted when a choke occurs but its opposition is overcome by the centrifugal action of the weights, when said speed and pressure reach the predetermined limit. The governor then holds the speed substantially constant at that limit. One end of the spring 23 is threaded to a fixed nut that surrounds said end while'the. opposite end is secured to a movable abutment 24. This abutment is connected by a rod with one end ofa bell-crank lever 26 that is pivotally mounted within the casin 27. The other end of the lever is connected to the stem 28 of the valve 17.; Located at any suitable point, as for exam 1e, on the outside of the shell surroun ing the spring and in line with the weights 30, are stops 29 whlch limit the inward movement of the weights. These governor weights are in engagement with.

the stops for all speeds below that for which the governor is set, so that the valve 17 remains wide open, this being the ordinary sulting increase in the pressure of the air delivered by the compressor. This increase continues until the pressure is sufficient to overcome the choke or obstruction in the cupola when the load on the compressor returns to normal, accompanied by a decrease in the speed of the turbine. Assuming, however, that the choke or obstruction in the cupola is not readily overcome, the speed of the turbine will increase to a point where the governor becomes effective and prevents said speed becoming abnormally great by decreasing the admission of steam. It will be seen that under ordinary conditions the turbine is running with full steam admission and for all practical purposes without the governor, the speed and pressure varying somewhat with the load, that is, with the quantity of air discharged ,by the compressor. This action continues until the counter pressure and speed rise to a predetermined amount when the governor comes into service and maintains a constant speed and discharge pressure of the compressor.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Vhat I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination, a centrifugal compressor which delivers fluid at substantially constant pressure when driven at constant speed under normal delivery conditions, a fluid-actuated motor for driving the compressor, a regulating valve for the motor that is open to a fixed extent during the ordinary operation of the compressor and supplies a constant quantity of motive fluid to drive the compressor at a constant speed under normal delivery conditions and at an increasmg speed from normal speed up to a redetermmed limit above normal if the de ivery of the compressor is choked, and agovernor having a member that tends to hold the valve open and means responsive to said predetermined s eed that overcomes the action of said mem er and closes the valve to a greater or less extent when the speed tends to exceed said limit.

2. In combination, a centrifugal air compressor which delivers air at approximately constant pressure and volume so long as its outlet is unobstructed, a motor which is ungoverned during the ordinary operation of the compressor and is direct-connected to said compressor, means delivering a substantially constant supply of energy to the motor so that its speed increases as the load decreases below normal, and a speed governor which is ordinarily inactive and only comes into service to limit the speed of the motor by controlling the input of ener when the volume of fluid delivered by-t e compressor decreases below a predetermined amount and its pressure increases to a predetermined limit due to an obstruction in the compressor outlet. i

3. In combination, a motor which is connected to a centrifugal air compressor which delivers air at approximately constant pressure at constant speed and at higher'pressures at higher speeds, means furnishing a constant supply of energy to the motor during the ordinary operation of the compres- 10o sor and up to a predetermined increase in speed and delivery pressure, and a speed governor which is ordinarily inactive but becomes active at said predetermined speed to regulate the supply of energy to the mo- 105 tor and prevent a further increase in speed and delivery pressure.

4. In combination, a centrifugal compressor, a fluid-actuated motor for driving it, a valve controlling the supply of fluid to the 110 motor, and means for holding the valve open to afixed extent while the load is normal and during the decrease of the load to a certain point, said means including speed responsive mechanism that becomes active at 11 a speed corresponding to said point of decreased load and closes the valve to a greater or less extent.

5. In combination, a motor for driving a centrifugal air compressor, means furnish- 120 ing a substantially constant supply of energy to the motor during the ordinary operation of the compressor so that its speed increases above normal as the load decreases below normal, and a speed responsive mecha- 125 nism which is ordinarily inactive but becomes active at a predetermined increase in speed above normal to regulate the supply of energy to the motor to prevent a further increase in speed.

' 6. The method of operating motor-driven determined limit so as to prevent a further 10' Centrifugal compressors which consists in furnishing a substantially constant supply of energy to the motor during the ordinary operation of the compressor at normal load and .also as the load decreases so that the speed can increase with a decrease in load, and regulat-in .the supply of energy to the motor when t e speed increases to a preincrease in speed.

In witness whereof, I have hereunto set my hand this second day of March, 1908.

JOHN A; MCMANUB, Jr., 7 HENRY O. WEs'rENnAnr.

Images