US3161020A

US3161020A - Centrifugal compressing of low molecular weight gases

Info

Publication number: US3161020A
Application number: US273880A
Authority: US
Inventors: Haye Paul G La
Original assignee: Mechanical Technology Inc
Current assignee: Mechanical Technology Inc
Priority date: 1963-04-18
Filing date: 1963-04-18
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15

Description

Dec. 15, 1964 P. G. LA HAYE CENTRIFUGAL COMPRESSING OF LOW MOLECULAR WEIGHT GASES Filed April 18, 1965 3 Sheets-Sheet 1 .T 1 3-1- Q6/deff 'INVENTOR Dec. 15, 1964 P. G. LA HAYE CENTRIFUGAL COMPRESSING OF' LOW MOLECULAR WEIGHT GASES 5 Sheets-Sheet 2 Filed April 18, 1963 NN hm.

INVENTOR.

12104 67A/ An/5 Dec. l5, 1964 P. G. LA HAYE 3,161,020

CENTRIFUGAL coMPREssING oF Low MOLECULAR WEIGHT GASES Filed April 18, 1963 3 Sheets-Sheet 3 3,161,020 CENTRFUGAL CMPRESSHNG F LW MLECULAR WEIGHT GASES Paul G. La Haye, Schenectady, NSY., assignor to Mechanical Technology Incorporated, Latham, NX., a corporation of New York Filed Apr. 18, 19673, Ser. No. 273,3S0 1t) Claims. (Qi. @tl- 39.6%

This invention relates to the centrifugal compression of low molecular weight gases, and particularly to improved methods and apparatus for operating turbines from a source of low molecular weight gaseous fuel which, as made commercially available, is under a relatively low pressure. Gaseous fuel is available from supply mains where the pressure is considerably below that required for injection into gas turbine combustion systems, but is of low molecular weight and difficult to compress centrifugally until it exceeds the pressure in the combustion system of the turbine. Such fuel is far more difficult to compre-ss to a high pressure than is air or other higher molecular weight gases. In the past, the use of reciproeating or positive displacement compressors has generally been necessary in order to compress the gaseous fuel to the extent necessary to inject it into the combustion zone of a gas turbine and to provide control over the combustion process.

An object of this invention is to provide a relatively simple, inexpensive, safe and practical method and apparatus for centrifugally compressing low molecular weight gases.

Another object is to provide a more eiiicient performance of the task of centrifugally compressing a gaseous fuel of low molecular weight up to pressures enabling injection into the combustion zone of a gas turbine, which canbe made available at reasonable shaft speeds and where small gas quantities are required at high pressure ratios.

A further object of the invention is to provide a simple and effective method and apparatus for centrifugally compressing the gaseous fuel as received from the supply mains or other source to the pressure desired for injection into the combustion system of a gas operated turbine, which is eiiicient, trouble free, compact, and powered by the turbine unit, and which permits control of primary combustion air so that the position and intensity of the combustion process can be externally controlled to some degree, which eliminates the need for any expensive compressor and control system to maintain the desired pressure ratio of fuel to main-turbine combustor pressure; and to provide a source of low pressure gas at a reasonable `temperature for use in iiuid seals and as a cooling gas for turbine Wheels andv other components, and which may provide a drive for turbine accessories and auxiliaries such as Water pumps.

A further object is to provide for the combustion of gases with a W energy content which cannot in-thernselves maintain combustion, but can, when enriched with a combustible fuel be combustible, and to further provide for the control of the mixture of a low energy gas and high energy gas to obtain maximum thermal eiciency.

Other objects and advantages will appear from the following description of several embodiments of the linvention, and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

United States Patent O FIG. 1 is a schematic diagram of turbine apparatus 3,161,020 Patented Dec. 15, V1964 ICC ugal compressor that may be employed to compress low molecular weight gases.

In Iaccordance with this invention, a low molecular weight gas, which is difficult to compress` adequately in centrifugal compressors, is mixed with a higher molecular weight gas, and this mixture may then be easily and efficiently centrifugally compressed. For example, commerically available fuel gas is of low molecular weight, and it cannot be suciently compressed in small quantities `in a centrifugal compressor for injection into combustion systems used to drive turbines. By iirst mixing such low molecular weight gas with air, for example, which has a higher molecular Weight, in a proportion less than is' necessary to support combustion of the mixture, this mixture of air and fuel gas may be easily centrifugally compressedsufiiciently to enable its delivery into the combustor of the combustion system of a gas turbine. The necessary compression of a low molecular weight gas, such as a fuel gas, may be easily obtained according to this invention at reasonable shaft speeds and impeller tip speeds, instead of the use of reciprocating or `positive displacement pumps. The power required for centrifugally compressing such a premixture of air and gaseous fuel is so small that the compression of the air and gas mixture may be obtained `in a simple and practical manner through energy obtained from the turbine system, either by a direct drive from the shaft or from the expansion of gas from the turbine system.

In the embodiment of the invention illustrated in FIG. l, the gas powered turbine unit, designated generally by reference 1, includes the air inlet hood 2, lea-ding to an air compressor 3 that is operatively coupled to and driven by one or more turbine wheels or units 4 and 5, an exhaust hood 6, and a coupling or clutch 7 through which the turbine rotor may be drivingly connected to a load 3. 'Ihe load may be connected to an independent turbine wheel which is not connected mechanically to the turbine wheel driving the main compressor. The power for operation of the rotor is obtained from combustor means 9 in which the fuel gas and air are burned, and the hot combustion gases delivered therefrom to the turbine wheels or rotor units d and 5. Air for combustion is delivered under pressure from the compressor 3 to the combustors 9 through passages or pipes 10 and gaseous fuel under pressure is delivered to the combustors 9 by pipe 11.

Gaseous fuel from a supply source, such as the main 12 of a commercial supply of natural or manufactured gas or othercombustible gas is Withdrawn through pipe 13 under control of a valve 14 and passed through a mixer or carburetor 15 in which it is mixed with primary air or any other gas having a higher molecular Weight than the primary fuel, such as carbon monoxide which in itself is also a fuel and will supplement the primary fuel, for example, supplied thereto through pipe 16 under the control vof a valve 17. This mixture of higher molecular weight gas and gaseous fuel is passed by means of a pipe 18 to a centrifugal compressor 19 having one or more stages of compression with and without cooling between stages. In the example illustrated, this compressor 19 has two

stages

20 and 21 connected by a pipe 22. This compressor 19 is powered by an auxiliary turbine 23 whose shaft 24 is drivingly connected to the rotors of the

compressor stages

20 and 21.

Compressor rotors

29 and 21 may also be driven directly by the main turbine shaft. The pipe 18 is connected to the inlet .port of the rst compressor stage 20, and after compression in this stage the mixture is passed through pipe 22 to the inlet port of the second compressor stage 21. The fully compressed mixture of air and gas is passed by pipe 11 from stage 21 to the combustors 9 of the main turbine 1. While the turbine 23 that operates the multi-stage compressor 19 may be any power source, it is preferably an auxiliary turbine supplied by energy obtained from the main turbine unit. In this example of the invention, this energy is a diversion of some of the compressed air from the compressor 3 through pipe 25 to the inlet of this turbine 23, the outlet of this turbine 23 being connected to atmosphere by pipe 26. A valve 27 in the air line 25 enables control of the speed of the compressor 19.

In this example of FIG. 1, air entering the hood 2 is compressed in compressor 3 and delivered to `the combustors or combustor means 9 through pipes 10. Gaseous fuel and an amount of air considerably less than `the amout required to support combustion of the mixture, and which amount of air may be called less than the stoichiometric amount necessary to support combustion of the fuel gas, are mixed in any suitable mixer or carburetor and compressed in the compressor 19 and delivered by pipe 11 to the combustors or combustor means 9. The compressor 19 is operated by turbine 23 powered by compressed air from the compressor 3. The primary air which is mixed with the gaseous fuel makes the compression of the fuel very much simpler and easier because the air adds suiiicient molecular weight to the mixture to enable its full and easy compression to the extent or pressure necessary for its injection into the combustors. While the amount of primary air added to the gaseous fuel must, for safety, be less than that necessary to support combustion of the mixture, i.e., less than the stoichiometric mixture for combustion, I have found that about half of the amount of air necessary to support combustion of the fuel gas gives adequate and excellent compressibility to the mixture, without danger of explosion or premature combustion of the mixture, even if there should be some air leakage into the mixture before it enters the combustors 9. The compression of the fuel air mixture may be now easily accomplished in a conventional or any centrifugal compressor at top speeds and shaft speeds which are within present day technical capabilities, such as approximately 60,000 r.p.m. and tip speeds below 1400 ft./sec., and within .the limitations imposed by the materials used or available.

In the embodiment of the invention illustrated in FIG. 2, the construction is similar to that shown in FIG. l, and identical parts have the same reference numerals in both FIGS. 1 and 2. The main difference between FIGS. l and 2 is .that whereas the pipe 25 of FIG. 1 was connected directly to the air compressor 3, in FIG. 2 it is identified by reference numeral a and is connected instead to one of the stages of the main turbine, such as to the first stage 4, so that some of the combustion gases that drive the turbine wheel in the first stage 4, instead of going to the second stage 5, are diverted to the auxiliary turbine 23 for the compression of the fuel air mixture.

In the embodiment of the invention illustrated in FIG. 3, the difference from FIGS. 1 and 2, is that the

pipes

25 and 25a of FIGS. 1 and 2, respectively, are replaced by a pipe 25C that is connected to the main air compressor 3 to receive compressed air therefrom, and is passed through a heat exchanger 28 disposed in the exhaust hood 6, and then through valve 27 to the auxiliary turbine 23. The compressed air received from compressor 3 is heated in the exhaust hood by heat exchanger 2S, where .the air receives further energy in the form of heat, and then the heated air is delivered to the auxiliary turbine 23 to operate the latter.

In the embodiment of the invention illustrated in FIG. 4, the arrangement is the same as in FIGS. 1-3 except that pipes 25, 25h, and 25e of FIGS. 1-3, respectively, are replaced with another pipe 25d with control valve 27 therein. One end of pipe 25d is connected to the main air compressor 3 to receive compressed air therefrom, and this airis delivered to an auxiliary combustor 29. A branch pipe 30 having a control valve 31 therein connects pipe 11 to the auxiliary combustor 29, and some of the compressed air and gaseous fuel from compressor stage 21 is supplied to the auxiliary combustor 29 where it burns with the aid of the secondary air from the compressor 3. The gases of combustion from combustor 29 are delivered by pipe 32 to auxiliary turbine 23 to operate it. Branch pipe 30 may be connected directly to fuel gas header 12 rather than pipe 11 when the gas pressure in (12) is greater than in pipe (25d), thereby simplifying the control of fuel to the auxiliary combustor.

The operation of the embodiments shown in FIGS. 24 is generally the same as explained for the embodiment shown in FIG. l, except as particularly pointed out in connection with each figure.

The air exhausted from the turbine 23 (FIGS. l and 3), instead of being exhausted to atmosphere, may be conducted to fluid seals of turbines adjacent the turbine bearings to replace the air supply now provided for the seals adjacent to the bearings for preventing escape and loss of lubricants from the bearings, and also may be used to cool turbine wheels.

In the embodiment of the invention illustrated in FIG. 5, the apparatus there shown may be used to compress easily and with a minimum of power, Iany low molecular weight gas by first mixing it with a higher molecular weight gas, and then centrifugally compressing such mixture. As an example, it may be used to compress the low molecular weight fuel gas, such as is available in commercial fuel gas mains, by mixing it w-ith air in an amount insufficient to support combustion of the fuel gas, and then compressing it in a two-stage compressor and delivering it to a turbine combustor. It is a physical illustration of suitable mixing and compressing means for the fuel gas and air that is illustrated only schematically in FIGS. 1-4, but which may be employed to mix any low molecular weight gas with any higher molecular weight gas, and compress the mixture centrifugally for any purpose.

In FIG. 5, the low molecular Weight gas or primary fuel which it is desired to centrifugally compress, such as natural or manufactured gas, for example, is supplied to the compressing apparatus by conduit 33, and the higher molecular Weight or secondary gas, which may be a fuel that does not burn by itself but increases the molecular weight of the mixture when mixed with the primary fuel, is supplied to the compressing apparatus by conduit 34. Examples of this secondary or higher molecular weight gas are air, blast furnace tail gases, and other low energy content but high molecular weight fuel gas. The primary gas or fuel supplied by conduit 33 is delivered by a nozzle 35 into an extension 36 of the conduit 34 diverging in the direction of flow of the gas in conduit 34. The proportions of the primary and secondary gases in the mixture may be controlled by a tapered control rod 37 disposed in the nozzle 35. The rod 37 is adjustable in a direction lengthwise of itself to move its tapered free end to various extents through the discharge orifice of the nozzle, and thus vary selectively the amount of primary or low molecular weight gas which is introduced into and mixes with the stream of the secondary or higher molecular weight gas. The conduit 36 as it becomes progressively larger in diameter in a direction away from the nozzle 35, delivers the mixture to the intake port 38 of the two-stage centrifugal compressor illustrated.

This compressor includes a main shaft 39 rotatably mounted near its opposite ends in suitable bearings 40 in a housing 41. Fixed on the shaft 39 are a first stage impeller or rotor 42 with vanes or blades 43, and a second stage impcller or rotor 44 with vanes or blades 45 arranged in succession along the shaft 39. Further along the shaft 39 and fixed on its free end is a turbine disc 46 provided at its periphery with a plurality of turbine blades or buckets 47 arranged in spaced apart relation along the periphery of the disc 46. The disc 46 is enclosed in a housing 48 which tapers to a peripheral channel 49 in close clearance with the disc 46, with the buckets 47 extending through the channel into a conduit 50 that extends crosswise or axial of the disc 46 and progresses crosswise of the disc 46 against the buckets or blades 47 to cause rotation of the disc 46 and through it of the shaft 39. The conduits u lead from the disc 46 to a collector 54 that is connected to an exhaust conduit 58 that in turn leads to seals, to cooling or to atmosphere.

The mixture of gases from conduit 36, upon entering the intake port 38, is discharged through an annular intake passage 56 against the radially inner ends of the vanes 43 and these rotating vanes force the gas mixture radially outward into and through a narrow passage 57 having across it a plurality of diffuser vanes 58a. The passage 57 then leads radially towards the shaft 39 and discharges its gases that were compressed in the first stage by vanes 43 against the inner ends of the vanes 45 of rotor impeller 44 that is fixed on rotary shaft 3%. The vanes 45 lead outwardly to the periphery of the second stageiimpeller 44 and are delivered, further compressed, into la passage 59 having across it diffuser vanes 60. The passage 59 discharges this further compressed gas mixture into an annular collector 61 which has an outlet pipe 62 which leads to the combustors of the main gas turbine.

|This compressor of FIG. 5 has been explained in connection with gas turbines where it has a very important use, but it can be used, when the turbine 46 is driven by any compressed gas or replaced by other motive means, to centrifugally compress with a low power consumption, a mixture of any low molecular weight gas and any gas of higher molecular Weight.

It will be understood that various changes in the details, materials, steps and -arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art Within the principle and scope of the invention as. expressed in the appended claims.

I claim:

1. A gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine, comprising:

(a) a gas turbine unit having a compressor, a combustor, and a turbine, said turbine being connected to said compressor and having an output shaft;

(b) a gaseous fuel compressor unit having a centrifugal compressor assembly for compressing and delivering a gaseous fuel mixture to said combustor at a pressure slightly higher than the pressure in said combustor;

(c) a turbine forming part of said gaseous fuel cornpressor unit connected to said centrifugal compressor assembly and having a highl pressure gas supply line connected to said gas turbine unit for effecting movement of said turbine;

(d) carburetor means connected to said compressor assembly for supplying a mixture of gaseous'fuel thereto;

(e) a low molecular weight gaseous fuel supply conduit connected to said carburetor means at one end and having its other end connected to a commercial fuel gaseous supply main containing high energy low molecular weight fuel gas at a pressure slightly higher than atmospheric pressure;

(f) a secondary gas lconduit containing a high molecular weight gas connected to said carburetor means; and

(g) control means associated with said carburetor for controlling mixture of said gases to produce a relatively high molecular weight gaseous fuel mixture, whereby said centrifugal compressor is able to raise 6 the pressure of said mixture above that in the combustor of said gas turbine unit at a high eiciency, and to deliver it to the combustor of said gas turbine unit.

2. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine as set forth in claim 1 wherein said secondary conduit contains air and said carburetor means mixes said air with said low molecular weight gaseous fuel in an amount considerably less than is necessary to support combustion.

3. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine as set forth in claim l wherein the compressor of said gas turbine unit is connected to said high pressure gas supply line for the turbine of said gaseous fuel compressor unit.

4. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine as set forth in claim 1 wherein said high pressure gas supply line connected to the turbine of said gaseous fuel compressor unit has a heat exchanger therein for heating ythe gas supplied to said turbine.

5. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply toa gas turbine as set forth in cl-aim 1 wherein said centrifugal compressor assembly comprises a first and a second centrifugal compressor stage.

6. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine as set forth in claim 1, wherein said gaseous fuel compressor unit has a central shaft on which said turbine and said centrifugal compressor assembly are integrally mounted. Y

7. The gas turbine system using a centrifugal compressor for supplying a gaseous fuel supply to a gas turbine as set forth in claim l, wherein Said carburetor means is formed by the juncture of said fuel gas supply conduit and said secondary gas conduit, and said control means comprises a tapered movable rod in said low molecular weight fuel gas supply conduit for controlling the supply of low molecular Weight fuel gas.

8. The method of supplying gas fuel of low molecular Weight from `a relatively low pressure source to a gas turbine having a combustor which receives compressed air at a high pressure from the gas turbine compressor unit, which comprises:

(a) mixing said low pressure low molecular weight high energy gaseous fuel with a low energy high molecular weight gas in suiicient proportion to give a relatively high energy and high molecular weight gaseous fuel mixture;

(b) centrifugally compressing said gaseous fuel mixture to a pressure greater than that in the combustor section of the gas turbine;

(c) adding sufficient air to said compressed gas mixture to make it combustible;

(d) burning this mixture of compressed gases with said air; and

(e) operating a turbine with said burned gases.

9. The method of operating 'a gas turbine from a relatively low pressure source of high energy low molecular Weight gaseous fuel as set forth in claim 8, and effecting the centrifugal compression of said low and high molecular weight gases with energy from said turbine.

l0. A method of supplying gas fuel 0f low molecular weight from a relatively low pressure source to .a gas turbine having a combustor which receives compressed air at a high pressure from the gas turbine compressor unit, which comprises:

(a) mixing said low pressure low molecular weight high energy gaseous fuel with air in sutiicient proportion to give a relatively high energy and high molecular Weight .4 gaseous fuel mixture, the amount of air being considerably less than necessary for combustion of such mixture;

(b) centrifugally compressing said gaseous fuel mixture to a pressure greater than that in the combustor 5 section of the gas turbine solely by centrifugal means and by at least one centrifugal stage compressor;

(c) adding suicient air to said compressed gas mixture to make it combustible;

(d) burning this mixture of compressed gases with 10 said air; and

(e) operating a turbine with said burned gases.

References Cited in the file of this patent UNTED STATES PATENTS McKee Dec. 8, Garretson July 3, Traupel Nov. 29, Sedille Dec. 16, Forsling May 11, Torell Jan. 24, Shannon et al Mar. 11, Grifth May 23, Schropp July 11,

Flanders Sept. 24,

Claims

1. A GAS TURBINE SYSTEM USING A CENTRIFUGAL COMPRESSOR FOR SUPPLYING A GASEOUS FUEL SUPPLY TO A GAS TURBINE, COMPRISING: (A) A GAS TURBINE UNIT HAVING A COMPRESSOR, A COMBUSTOR, AND A TURBINE, SAID TURBINE BEING CONNECTED TO SAID COMPRESSOR AND HAVING AN OUTPUT SHAFT; (B) A GASEOUS FUEL COMPRESSOR UNIT HAVING A CENTRIFUGAL COMPRESSOR ASSEMBLY FOR COMPRESSING AND DELIVERING A GASEOUS FUEL MIXTURE TO SAID COMBUSTOR AT A PRESSURE SLIGHTLY HIGHER THAN THE PRESSURE IN SAID COMBUSTOR; (C) A TURBINE FORMING PART OF SAID GASEOUS FUEL COMPRESSOR UNIT CONNECTED TO SAID CENTRIFUGAL COMPRESSOR ASSEMBLY AND HAVING A HIGH PRESSURE GAS SUPPLY LINE CONNECTED TO SAID GAS TURBINE UNIT FOR EFFECTING MOVEMENT OF SAID TURBINE; (D) CARBURETOR MEANS CONNECTED TO SAID COMPRESSOR ASSEMBLY FOR SUPPLYING A MIXTURE OF GASEOUS FUEL THERETO; (E) A LOW MOLECULAR WEIGHT GASEOUS FUEL SUPPLY CONDUIT CONNECTED TO SAID CARBURETOR MEANS AT ONE END AND HAVING ITS OTHER END CONNECTED TO A COMMERCIAL FUEL GASEOUS SUPPLY MAIN CONTAINING HIGH ENERGY LOW MOLECUALR WEIGHT FUEL GAS AT A PRESSURE SLIGHTLY HIGHER THAN ATMOSPHERIC PRESSURE; (F) A SECONDARY GAS CONDUIT CONTAINING A HIGH MOLECULAR WEIGHT GAS CONNECTED TO SAID CARBURETOR MEANS; AND (G) CONTROL MEANS ASSOCIATED WITH SAID CARBURETOR FOR CONTROLLING MIXTURE OF SAID GASES TO PRODUCE A RELATIVELY HIGH MOLECULAR WEIGHT GASEOUS FUEL MIXTURE, WHEREBY SAID CENTRIFUGAL COMPRESSOR IS ABLE TO RAISE THE PRESSURE OF SAID MIXTURE ABOVE THAT IN THE COMBUSTOR OF SAID GAS TURBINE UNIT AT A HIGH EFFICIENCY, AND TO DELIVER IT TO THE COMBUSTOR OF SAID GAS TURBINE UNIT.