US2926493A - Gas turbine with waste heat steam generator - Google Patents

Description

March 1, 1960 A. J. POOLE ETAL GAS TURBINE WITH WASTE HEAT STEAM GENERATOR 2 Sheets-Sheet 1 Filed March 7, 1955 INVENTOR ARTHUR J. POOLE CLYDE B BAVER BY MORNEY March 1, 1960 A. J. POOLE ErAL 2,926,493

GAS TURBINE WITH WASTE HEAT STEAM GEIIERATOR Filed March 7, 1955 2 Sheets-Sheet 2 INVENTOR ARTHUR J. POOLE CLYDE B. BAVER nit GAS TURBINE WITH WASTE HEAT STEAM GENERATOR Arthur J. Poole, Belleville, and Clyde B. Baver, Fan-' wood, NJ., assignors to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey The invention relates to steam generating apparatus for recovering heat from the exhaust productsof a gas turbine. More specifically, the invention relates 'to an arrangement of a steam generating unit within an exhaust gas duct leading from the turbine and having agas fuel burner positioned in the throat of a venturi shaped duct at a position intermediate of the turbine and the steam generating unit.

In the elastic fluid power plant the lowest pressure gas turbine exhausts its gases at a temperature within the range of 600 F. to 900 F. so that it is important to place a heat trap through which the gas must flow in order to capture the heat from the gases and increase the economics of the cycle. The present invention involves a steam generating unit as the-heat trap, furnishing steam for heating or other processes. This steam'generating unit may perform all of the duties which a detached steam generating unit would perform, in that the unit is arranged to burn gaseous fuel in the high excess oxygen gas turbine exhaust gas so as to increase the heat content of the gases flowing over the steam generating surfaces thus allowing the steam generating unit to be operated independently of the load of the gas turbine.

The invention will be described with reference to the accompanying drawings, showing a preferred embodiment of the invention.

In the drawings:

Fig. 1 is a sectional side elevation of the steam generating unit;

Fig. 2 is a plan section of Fig. 1 taken along the line 2-2 and including a schematic representation of the gas turbine;

Fig. 3 is a vertical section of the steam generator at the line 3-3 of Fig. 1; and

Fig. 4 is a section through the gaseous fuel burner and duct of Fig. 1, taken on the line 4-4 of Fig. 1.

States Patent A combustion gas turbine 10 discharges its spent gases 1 into the exhaust duct 12 at a temperature within the range of 600 F. to 900 F. Disposed within the duct is a steam generating and superheating unit having vertical steam generating tubes 14 extending between the upper drum 16 and the lower drum 18.

The unit is arranged within a rectangularly shaped and enlarged portion of the duct 12 as shown in Figs. 1 to 3 and is top supported by steelwork 19. In addition to the steam generating tubes 14, there is a feed water economizer 22 adjacent the gas outlet 23 for heating the water prior to its entry into the upper drum 16. A superheater 20 is disposed in front of the generating tubes 14 and arranged to heat the steam leaving from the upper drum 16.

The portion of the duct 12 between the turbine 10 and the steam generating section 14 is arranged in the general shape of a venturi in that there is a convergent section 24 and a divergent section 26 intersecting at a minimum area or throat 28. Thus, the gas as it leaves the turbine is accelerated to a maximum velocity as it Patented Mar. 1, 1960 passes through the throat 28 and is smoothly decelerated to pass over the superheater 20 and the steam generating tubes 24.

Positioned within the venturi throat 28 is a gaseous fuel burner 30 having eight uniformly circumferentially spaced radially arranged and inwardly extending perfo-' rated burner tubes 32. Four of the tubes are connected to the fuel supply'manifold 34, and the other four to the similar supply manifold 36. Each of these manifolds may be supplied from any convenient fuel source (not shown).

v The duct 12 being arranged with a venturi section allows the gas to be accelerated to a high velocity and decelerated to a low velocity with a minimum fluid pres sure loss. While obtaining the minimum pressure loss for a high velocity, the positioning of the burner 30 at the throat of the venturi results in effective mixing of the gas with the gaseous fuel.

While in accordance with the provision of the statutes, there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

v 1. In an elastic fluid power plant, a combustion gas turbine, duct means arranged to receive gases from the exhaust of said turbine, steam generating and heating means arranged in said duct means, said duct means having a venturi shaped segment forming a combustion chamber at a location between said turbine and steam generating means, said venturi segment including a converging gas inlet portion and a divergent gas outlet portion connected at their minimum area to form a throat thereat said generating and heating means positioned immediately adjacent the outlet end of said divergent portion and includes an upper steam drum, a lower water drum, and a plurality of generating tubes connecting said drums, said generating tubes extending transversely of said duct and gas flow, a super-heating element and economizer section, a burner means positioned in said duct at the throat of said venturi segment to initiate and maintain ignition thereat to increase the heat content of said exhaust gases, said burner means including a plurality of circumferentially spaced, radially arranged, inwardly extending gas burner tubes having gas discharge orifices longitudinally spaced along said tubes, said superheating element being disposed in said duct between said steam generating tubes and said divergent outlet end for superheating the steam generated by the flow of said heated exhaust thereover and said economizer section being positioned downstream of said steam generating means for heating water supplied to said generating tubes, said heating exhaust gases being free to expand through the diverging outlet portion of said venturi segment to provide for uniform distribution of the heating gases through said steam generating and heating means.

2. In an elastic fluid power plant, a combustion gas turbine, duct means arranged to receive gases from the exhaust of said turbine, steam generating means arranged in said duct means, said duct means including a venturi shaped segment forming a combustion chamber at a location between said turbine and steam generating means, said venturi segment including a convergent gas inlet portion and a divergent gas outlet portion connected at their minimum area to form a throat thereat, and a burner means positioned in said duct at the throat of said venturi segment for initiating and maintaining the ignition of a fuel thereat for increasing the heat content of said exhaust gases, said heated exhaust gases being free to expand through said venturi segment prior to flowing in heat exchange relationship with said steam generator whereby the ex pansion of said heated exhaust gases through said divergent section recovers a portion of the pressure-loss occasioned by the increased velocity head of the exv haust gases in fiowing through said throat portion and provides uniform distribution of the heating gases through the steam generating means.

3. In an elastic fluid power plant, a combustion gas turbine, duct means arranged to receive gases from the exhaust of said turbine, steam generating means arranged in said duct means, said steam generating means including steam generating tubes extending between upper and lower drums and arranged transverse to the gas flow, said duct means having a venturi shaped segment forming a combustion chamber at a location between said turbine and steam generating means, said segment including a convergent gas inlet portion and a divergent gas outlet portion connected at their minimum area to form a throat thereat, and the maximum area of said divergent gas outlet portion connecting to said steam generating means, and a burner means positioned in said duct at the throat of said venturi segment for initiating and maintaining the ignition of a fuel thereat for increasing the heat content of said exhaust gases, said heated exhaust gases being free to expand through the diverging outlet end portion of said venturi segment prior to fiowing in heat exchange relationship with said steam generator whereby the expansion of said heated exhaust gases through said divergent section recovers a portion of the pressure loss occasioned by the increased velocity head of'thegases in flowing through said throat portion and provides uniform distribution of the heating gases through the steam generating means.

4. In an elastic fluid power plant, a combustion gas turbine, duct means arranged to receive hot gases from the exhaust of said turbine, steam generating means arranged in' said duct means, said steam generating means the diverging outlet end of I including steam generating tubes extending between upper and lower drums and arranged transverse to the gas flow, said duct means having a venturi shaped segment forming a combustion chamber at a location between said turbine and steam generating means, said segment including a convergent gas inlet portion and a divergent gas outlet portion connected at their minimum area to form a threat thereat and the maximum area of said divergent gas outlet portion connecting to said steam generator means, and a gas burner including a plurality of circumferentially spaced radially arranged inwardly extending perforated burner tubes positioned in said duct at the throat of said venturi segment for initiating and maintainingthe, ignition of a gaseous fuel thereat for increasing the heat content of said exhaust gases, said heated exhaust gases being free to expand through the diverging end of said venturi segment prior to flowing in heat'exchange relationship with said steam generator whereby the expansion of saidheated exhaust gases through said" divergent section provides for the recovery of a portion of the pressure loss occasioned by the increased velocity head of the gases in flowing through said throat portion and provides for uniform distribution of the heating gases through the steam generating means.

References Cited in the file of this patent UNITED STATES PATENTS

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