US3749047A

US3749047A - Combined gas turbine

Info

Publication number: US3749047A
Application number: US00165130A
Authority: US
Inventors: S Tamaru; K Teshima
Original assignee: Mitsui Engineering and Shipbuilding Co Ltd
Current assignee: Mitsui Engineering and Shipbuilding Co Ltd
Priority date: 1970-07-28
Filing date: 1971-07-22
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31
Also published as: DE2137531A1; NL7110314A; FR2099644B1; GB1304318A; FR2099644A1; JPS4910762B1

Abstract

A gas turbine arrangement for ships in which a low temperature turbine using low grade fuel is mounted above the deck and is directly coupled to a compressor for a second turbine mounted in the engine room which operates at high temperature and with high quality fuel. The entire output of the second turbine drives the ship propeller, preferably through reduction gearing. The compressed air from the above-deck turbine may be heated by the exhaust gases from the below-deck turbine. The above-deck turbine may be a two-stage arrangement having an intercooler between the two stages of compression. Additionally a bleeder system and heat exchanger may be incorporated in the output of the first compressor.

Description

United States Patent 1 1 Tamaru et al.

[ COMBINED GAS TURBINE [75] Inventors: Shigeo Tamara; Kiyomi Teshima,

both of Okayama, Japan [73] Assignee: Mitsu Shipbuilding and Engineering Co. Ltd., Tokyo, Japan [22] Filed: July 22, 1971 [211 Appl. No.: 165,130

[30] Foreign Application Priority Data 6/1956 Barrett et al 60/39.l5 3/1965 Schell et a]. 60/221 [5 7] ABSTRACT A gas turbine arrangement for ships in which a low temperature turbine using low grade fuel is mounted above the deck and is directly coupled to a compressor for a second turbine mounted in the engine room which operates at high temperature and with high quality fuel. The entire output of the second turbine drives the ship propeller, preferably through reduction gearing. The compressed air from the above-deck turbine may be heated by the exhaust gases from the below-deck turbine. The above deck turbine may be a two-stage arrangement having an intercooler between the two stages of compression. Additionally a bleeder system and heat exchanger may be incorporated in the output of the first compressor.

5 Claims, 9 Drawing Figures PATENTEU 3,749,047

sum 2 or 3 FIG; M B2 is that suction air volume of the 1 COMBINED GAS TURBINE The present invention relates bine effectively used for ship.

The gas turbine is light in weight and small in size but large in output, and thereby widely used for aircraft. However application of gas turbine to ship is extremely limited and only found specifically in naval craft. The reason for this is that the use of low grade fuel is difficult because of increase of fuelexpense. Further reason gas turbine per output of exhaust gas generto a combined gas turis large, thereby a large amount ated and a large sectional area of exhaust ducts required in spite of the fact that the gas turbine engine itself is small in. size. These factors are of course. disadvantageous to apply the gas turbine to ships.

The present invention has for its object to remove the above mentioned disadvantages, and is characterized in that two or more gas turbines are combined to form a composite cycle, so that. amount of suction air introduced in the output turbine isdecreased, and thereby decreasing cross-sectional area of the suction and the exhaust ducts thereof.

The combined gas turbine in accordance with the present inventionare. such composed that an air compressor is driven by. means of an independent gas turbine which consumes chiefly low grade fuel such as Bunker C heavy oil or Heavy Marine Fuel Oil and high pressure air discharged from the compressor is introduced into combustor of output turbine and then the produced hightemperature and high pressure gas is introducedintothe output turbine to obtain output.

In the drawings:

FIGS. 1a and lb are schematic diagrams showing conventional gas turbines;

FIG. 2 is a schematic diagram showing the present invention;

FIG. 3 is a schematic diagram showing a case in which the present invention is applied to ships; and

FIGS. 4 through.8 are schematic diagrams showing other embodiments of the present invention applied to ships respectively.

Referring to the drawings, in accordance with the present invention ordinary gas turbinesA and B shown in FIGS. and lb are combined to compose one unit as shown in FIG. 2. The combined gas turbine comprises ,a compressor side C and an output side D. The compressor side comprises a compressor C combustor 8,, output turbine T, and compressor C, connected to the output shaft of the turbine T The high pressure air. discharged from the compressor C, is introduced in the combustor B, of the output side turbine'to drive the turbine T In this case, when the output of turbine is represented by W, ant the requiredpower for compressor isW the following equation must be held:

From this relation, it will be seen by simple calculation that the power output HP; isequal to the sum of output HP ofthe gas turbine A and output HP; of the gas turbine B. That is to say, with respect to the output, the present invention does not show a profit in particular. However, theeconomy of fuel cost and the reduction of space for the suction and the exhaust ducts for installing the turbine in the ship are greatlyaffected by the present invention. The reasone will be described hereinafter. The output of the gas turbine increases with the temperature of gas in the combustor B thereof. If low grade fuel such as Bunker C heavy oil or Heavy Marine Fuel Oil is used, ash is generated, and turbine blades are corroded at high temperature. Therefore, gas temperature is at present considered not to exceed 750C. In the combined gas turbine according to the present invention, .flow rate of air introduced into the combustor B, by means of the compressor C, is about two point three times as much as that of the combustor 8,. This means that fuel consumption ratio of the combustor B, is about percent of whole fuel consumption of the conbined turbine. The present invention can provide an economical combined turbine by using a low grade fuel in the combustor B of large fuel consumption ratio, even if the fuel consumption rate per output is increased owing to low gas temperature below 750C. While, high quality fuel such as light oil is used in the combustor 8,, high power output is obtained by raising the gas temperature.

Consideration is now given to amount of air necessary for obtaining a required power output HP In the conventional single turbine, about two-thirds of output of the turbine is alloted for driving the compressor and about one-thirds of the output is available for use. This situation prevails also in the turbine of the present application. The turbine T of the present invention need not drive the compressor and sufiices to generate about one-thirds of power output comparing with the conventional turbine having the same output HP which means that the amount of air to be supplied to the combus'tor B decreases to about one-thirds of conventional case. Accordingly, the cross-sectional area of the duct leading to the combustor B, also becomes smaller.

The above rough calculation is based on an assumption that the combustors B and B are equal in temperature. However, the temperature of the combustor B is elevated higher than that of the combustor B Accordingly, the ratio of the required air volume is slightly different from the above value.

Explanation will be made about another embodiment, shown in FIG. 3, of the present invention. As shown in the drawing, the compressor side C shown in FIG. 2 is located above the deck and the output side D is arranged in the engine room and connected through the reduction gear R6 to the propeller. It is to be commented that GT (I) shown in the drawing represents the turbine of the compressor side in block.

By employing such arrangement, the duct system in the hull is enough to provide a duct for air to be supplied to the combustor B: only and the amount of air is only about one-thirds of the total required air as mentioned above. In addition, the air flowing into the combustor B: has been compressed by the compressor C below one-fifth or less of the initial volume, consequently, the cross-sectional area of the duct required for necessary output is reduced to one-tenth or less as compared with conventional systems.

The efficiency of the turbine may be improved by employing various known means such as preheating by e'xaust gas, two-stage compression, inter cooling, bleeder system, etc. as shown in FIGS. 4 through 8. The symbols GT (II), HE and IC shown in the drawings indicate a turbine, heat exchanger and inter coller respectively.

As will be obvious in the preceding description, according to the present invention, the economy of fuel cost is improved as a whole by using low grade fuel in the large ratio to whole fuel consumption, as well as the cross-sectional area of the air suction and exhaust ducts can be remarkably reduced. Besides, since the gas turbine consuming low grade fuel is located above the deck, maintenance of the gas turbine is easy.

What is claimed is:

l. A combined gas turbine drive for a ship having a hull closed at the top by a deck, a propeller for driving the ship having a propeller shaft extending longitudinally through the bottom of the hull, and an engine room in the bottom of the hull below said deck for housing the controls of the ship for driving the propeller, said drive for the ship comprising a first gas turbine, a combustor utilizing compressed air and fuel to generate the gas for driving said first turbine, means mounting said first turbine and combustor above the deck of said ship, a second turbine having an output shaft coupled to said propeller shaft, means mounting said second turbine below the deck of said ship in said engine room, a combustor for feeding combustion gases to said second turbine, means to supply a different fuel and compressed air to said combustor, said combustion burning said fuel and generating said combustion gases, a compressor for supplying compressed air to said second combustor, means mounting said compressor on the deck or above the deck of the ship, means coupling the drive shaft of said first turbine to said second compressor whereby said compressor is driven by said first turbine, and high pressure air lines extending from the compressor above the deck of the ship to the combustor for the second turbine.

2. A combined gas turbine drive according to claim 1 wherein said combustor for supplying gas to said second turbine is operative at high temperature and with high quality fuel and said combustor for supplying gas to said first turbine is operative with low grade fuel such as Bunker C heavy oil or Heavy Marine Fuel Oil.

3. A combined gas turbine drive for ships according to claim 1 including means to couple the entire output of said second turbine to the ship propeller.

4. A drive according to claim 3 wherein said coupling means consists of reduction gearing.

5. A drive for ships according to claim 1 including a heat exchanger to receive exhaust gases from the second turbine, and means to direct compressed air from said compressor through said heat exchanger prior to passing into said combustor.

Claims

1. A combined gas turbine drive for a ship having a hull closed at the top by a deck, a propeller for driving the ship having a propeller shaft extending longitudinally through the bottom of the hull, and an engine room in the bottom of the hull below said deck for housing the controls of the ship for driving the propeller, said drive for the ship comprising a first gas turbine, a combustor utilizing compressed air and fuel to generate the gas for driving said first turbine, means mounting said first turbine and combustor above the deck of said ship, a second turbine having an output shaft coupled to said propeller shaft, means mounting said second turbine below the deck of said ship in said engine room, a combustor for feeding combustion gases to said second turbine, means to supply a different fuel and compressed air to said combustor, said combustion burning said fuel and generating said combustion gases, a compressor for supplying compressed air to said second combustor, means mounting said compressor on the deck or above the deck of the ship, means coupling the drive shaft of said first turbine to said second compressor whereby said compressor is driven by said first turbine, and high pressure air lines extending from the compressor above the deck of the ship to the combustor for the second turbine.