US3053049A

US3053049A - Power plant installation

Info

Publication number: US3053049A
Application number: US731521A
Authority: US
Inventors: Henry J Blaskowski
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1958-04-28
Filing date: 1958-04-28
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11
Also published as: GB857811A; FR1220532A

Description

Sept. 11, 1962 H. J. BLASKOWSKI 3,053,049

POWER PLANT INSTALLATION Filed April 28, 1958 Economizer Economizer Steam Turbine Gas Turbine Generator Generator INVENTOR Henry J. Bloskowski $145M fat ATTORNEY bustion of the fuel within the boiler.

United States Patent ()fiice 3,53,049 Patented Sept. 11, 1962 3,053,t)49 POWER PLANT {INSTALLATION Henry J. Blaskowslri, New York, N.Y., assignor to Conlbustion Engineering, like. New York, N.Y., a corporation of Delaware Filed Apr. 28, 1958, Ser. No. 731,521 3 Claims. (Cl. 60-49) This invention relates generally to a power plant installation or organization employing a gas turbine and boiler combination.

More particularly the invention involves this combination wherein the quantity of exhaust gases from the gas turbine is such that it provides an oxygen supply much greater than that required by the boiler to support com- In accordance with the invention a portion of the exhaust gases from the turbine are introduced into the boiler together with the fuel with which the boiler is fired with these exhaust gases supplying the oxygen necessary to support combustion of this fuel. The portion of the gases that are not introduced into the boiler are directed through a bypass duct within which is positioned economizer surface f the boiler and also within which is positioned a low temperature superheater section which is in series flow relation with a high temperature superheater section located within the boiler. Means are provided to controllably proportion the gas turbine gases introduced into the boiler and passed through the bypass. The organization is such as to provide a very eificient operation with the gas turbine gases having their temperature lowered to the point so that they can economically be discharged to atmosphere and at the same time a control of the superheat steam temperature is obtained.

Moreover, with the invention the boiler may be designed so that it can be operated without the turbine as when the turbine is shut down.

Accordingly, it is an object of this invention to provide an improved power plant installation employing a combined gas turbine and steam generator or boiler.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed descript-ion of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein the single figure is a diagrammatic representation of a power plant installation embodying this invention.

Referring now to the drawing the illustrative embodiment of the invention depicted therein comprises a gas turbine 16 that is of the type which produces substantially the same quantity of exhaust gas throughout the range of its operation, as for example, a single cycle, single shaft gas turbine. This turbine receives the hot gas supply from burners 12, which, in turn, receives compressed air from a compresser that is not here illustrated. The exhaust from turbine exits into duct 14, which, at the location 16, is divided into supply duct 18 that leads to boiler 20 and into bypass duct 22 which leads to stack 24 Via passage 36. Boiler 20 is tangentially fired in a conventional and well known manner by burners 26 and the exhaust turbine gases from supply duct 18 are admitted into the boiler through these burners. With these gases, which contain about 80% of the oxygen found in free air, supplying the oxygen requirements to support combustion of the fuel introduced into the boiler.

This illustrative boiler has the walls of its furnace into which the fuel is tangentially introduced and burned lined with steam generating tubes and it is provided with a steam and water drum 28 and mud drum 30 between which there is disposed steam generating tubes in the conventional manner. Forming part of this boiler installation is the high temperature steam heating surface 32 which is in the form of a series of tube platens or groups in spaced relation across the boiler with there being suitable baffles provided so that the combustion gases flow in the boiler as is indicated by arrows 34. The combustion gases pass through the passage 35 into duct 36 within which is positioned economizer surface 38 of the boiler with these gases after traversing this economizer surface passing into stack 24.

In order that the temperature of the turbine exhaust gases will be reduced to a suitably low value that these gases may economically be discharged to stack 24 there is provided in bypass duct 22 the economizer surface 4-2 which is supplementary to the economizer 38 and heats the water that is introduced into the steam and water drum 28 of the boiler with this surface 42 being a part of the surface for boiler 20. Also positioned in bypass duct 22 and upstream of economizer surface 42 is the low temperature superheater section 44. This superheater 44 receives steam from steam and water drum 28 through conduit 46, initially superheats this steam to some extent with the then superheated steam being conveyed to the high temperature superheater 32 by conduit 48. In high temperature superheater 32 the steam is finally superheated to its desired temperature and is discharged through conduit 50 which leads to steam turbine 52. Low temperature superheater 44 is so related to the high temperature superheater 32 that the amount of heat imparted to the steam in high temperature superheater 32 is much greater than that imparted to the steam in passing through the low temperature superheater 44. Of course, the temperature head, i.e., the temperature difierential between the steam and the gases passing over the superheater, in low temperature superheater 44 is much less than in high tem perature superheater 32. The reason for having a large difference in the heat absorbing effectiveness of these two superheater sections will be apparent hereinafter.

Gas turbine It} drives generator 52 while steam turbine 54 drives generator 56. Each of these generators is connected through suitable conductors to a common buss 58, which, in turn, connects to a varying load.

Engineering studies and operating experience have shown that maintaining a constant weight flow of gas over a superheater in a boiler through a wide range of loads causes a rise in total steam temperature with a decrease in load. This characteristic is of course contrary to that exhibited by conventionally fired boilers and poses a serious problem of superheat metal selection, protection and control. Another problem that is encountered in a combination such as being considered herein is the operation of the steam generator independently of the gas turbine as when the gas turbine is shut down for some reason or other. It may be desirable to obtain the same capacity and steam temperature when the boiler is fired conventionally using atmospheric air. Under this operation the temperature of gases generated in the boiler for a particular load on the boiler is much greater than that produced with combined boiler and gas turbine operation. This is so because the economizer surface in the bypass that is employed to reduce the temperature of the turbine exhaust gases is not eifective so that for a similar load on the boiler much more fuel must be fired into the boiler to make up for the loss of this surface and generate the required amount of steam. This increased gas weight and temperature of course effects the superheat tending to increase it.

Both of the aforementioned problems are solved by dividing the superheater into a low temperature section 44 and a high temperature section 32 as described hereinbefore. Only sufiicient superhea-t surface is provided in the high temperature section 32 to give the required steam temperature at the desired load when the boiler is operated independently of the gas turbine, i.e., only sufficient superheater surface is installed to obtain full steam temperature with coldair firing. Fan 33 supplies the air in this instance. The additional surface provided in low temperature section 44 is that amount of surface that is required for combined operation of the boiler and the gas turbine where only turbine gas is supplied to the boiler furnace to support combustion. With this organization boiler 20 may be operated When the gas turbine is shut down and the desired steam temperature obtained and when combined operation of the gas turbine and boiler is bad the additional heat required for superheating the steam is picked up in the low temperature superheater 44 and accordingly with this combined operation the required steam temperature is also obtained. A further advantage of this arrangement employing superheater section 44 in bypass 22 and upstream of economizer 42 is that there is a reduction in the amount of heat that must be imparted to economizer surface 42 in order to sufiiciently reduce the gas turbine gas temperature so that after traversing the surface 33 it may be discharged to stack 24- thereby reducing the possibility of and the amount of, if any, steaming in this economizer surface with it being desirable to maintain steaming in the economizer at a minimum so that scale and deposits will not form in the econo-mizer tubes.

A control is provided for the proportioning of the gas turbine exhaust gases through the supply duct 18 and the bypass duct 22, i.e., the proportioning of the gases that goes to each of these locations is adjustably controlled. This control is in the form of adjustable damper 60 located at the inlet of supply duct 13 and adjustable damper 62 located at the inlet of bypass duct 22 with damper 62 being one of a plurality of dampers disclosed in side by side relation across the duct entrance. It will be appreciated that the represented dampers are only illustrative of a control to controllably proportion the turbine exhaust gas flow through each of these ducts. It will further be appreciated that if no other change in the system is made, i.e., if the gas turbine and the boiler loads are not changed, an increase in the proportion of the gas turbine exhaust gases passing through bypass duct 22 relative to that through duct 18 will decrease the temperature of the steam delivered to the steam turbine while an increase in the proportion of these gases delivered to the furnace by duct 18 will increase the steam temperature.

In the operation of this power plant system wherein the gas turbine and the boiler are eifectively connected to and supply a common load, which is a variable one, there are three possibilities with respect to operation of the system as the load changes. The gas turbine and boiler may both accommodate the varying load, i.e., the output of the gas turbine and the boiler may be varied to accommodate variations in load; the output of the gas turbine may be maintained constant and the boiler may accommodate the load variations, i.e., the output of the boiler may be the only element of the combination that is varied to accommodate load changes; and the output of the boiler may be maintained constant and the gas turbine varied to accommodate load changes, i.e., the output of the gas turbine may be the only element that is varied to accommodate changes in the load.

In the first instance, i.e., where the gas turbine and boiler are jointly varied with load change, this operation tends automatically to compensate for the tendency of the steam temperature to rise with a decrease in load when the weight flow of gas through the boiler remains constant. This is so because if the load changes and is accommodated jointly between boiler and the gas turbine the temperature of the gas turbine gases decreases although the quantity of these gases remains the same. If the dampers 62 and 69 are not moved from their former position so that the same quantity of gas turbine gases is supplied to the furnace the effect of high temperature superheater section 32 is to cause the steam temperature to rise with a decrease in load. However, since the temperature of the gases flowing over low temperature superheater section 44 is decreased and the amount of gases flowing over this section remains the same the effect on this low temperature superheater section is to decrease the steam temperature. These two effects thus work to counteract each other. Since these effects will not be equal however, the dampers 60 and 62 may be adjusted to provide what is in the nature of verier control in this instance, with damper 60 being moved to decrease the gas flow into the furnace and damper 62 moved to increase the proportion of the turbine gases that flows through bypass duct 22 as the load decreases. Since high temperature superheater section 32 has a much greater heating effect than low temperature superheater section 44 this adjustment of the dampers will effect a decrease in the steam temperature. Thus as the load on the power plant installation decreases a greater proportion of the gases are passed through bypass 22 and the steam temperature is maintained constant. When the load is increased the opposite control effect is had.

When the output of the gas turbine is maintained constant and the boiler is operated to accommodate the variations in load, dampers 62 and 6% may be adjusted so as to provide a generally constant steam temperature throughout the load range at which the boiler operates. Here as in the instance where the boiler and gas turbine are varied together, as the load decreases the dampers are manipulated so that an increased portion of the gas turbine gases pass through the bypass 22 and accordingly over the low temperature superheated section 44. With an increase in load an opposite control effect is bad. With this control the temperature of the steam delivered to steam turbine 52 may be maintained generally constant.

Where the boiler is operated at a constant load and the output of the gas turbine is varied to accommodate the variations in load on the power plant an opposite control effect from that just described is provided in order that the temperature of the steam delivered to turbine 52 is maintained generally constant throughout the load range of operation of the gas turbine. As the load on gas turbine 10 decreases, the amount of gas turbine gases remains constant but the temperature of these gases decreases. It is thus necessary to have a larger proportion of these gases introduced into boiler 29 in order that the steam temperature may be maintained constant. Therefore as the load on the gas turbine decreases the proportion of the gases passing through bypass 22 is decreased with the result that the steam temperature may be maintained constant by controllably varying this proportioning. Contrarywise, as the load on the gas turbine increases a greater proportion of the gas turbine gases is passed through bypass 22 and a lesser proportion is introduced into the furnace with the control of this proportioning accordingly being such as to maintain the steam temperature delivered to turbine 52 constant.

It will thus be seen that with applicants novel arrangement an extremely efiicient operating organization is provided which permits boiler 20 to be satisfactorily operated when the turbine is not operated, which provides an extremely efficient combined operation of the turbine and the boiler and which provides for steam temperature control when either the gas turbine only swings variations of the common load, the boiler only swings these variations or the gas turbine and boiler together swing the variations of load.

While I have illustrated and described a preferred embodiment of my invention it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What is claimed is:

1. In combination, a gas turbine engine, a boiler fired with a suitable fuel, the turbine engine being such that the exhaust thereof provides a substantial excess of oxygen over that required to fire the boiler with the amount of exhaust gases remaining generally constant over a substantial load range, means introducing a portion of the turbine exhaust gas into the furnace to support combustion of the fuel therewithin, means bypassing the boiler with the remainder of the turbine exhaust gases, Water heating heat exchange means forming part of the economizer surface of the boiler disposed in said bypass means to absorb heat from the bypassing turbine exhaust gases, additional economizer surface over which both the bypass gases and the gases from the furnace pass a superheater for superheating the steam generated by the boiler and including a low temperature section disposed in said bypass means and a high temperature section located in the boiler said low temperature section and said high temperature section being such that the heat absorbed by the high temperature section is substantially greater than that absorbed by the low temperature section, and means provided to controllably proportion the turbine exhaust gases between the bypass means and the boiler.

2. The combination of a boiler having a furnace fired with a suitable fuel, a gas turbine operative to produce a generally constant amount of exhaust gases over a substantial load range with the exhaust gases containing substantially more oxygen than required to burn the fuel in the boiler, means for introducing a portion of these gases into the boiler to support the combustion of the fuel therein, means bypassing the boiler furnace with the remaining portion and passing said remaining portion over steam heating and economizer surface disposed in said bypassing means and connected into the boiler system, said steam heating surface being disposed upstream of said economizer surface in said bypassing means, additional economizer surface disposed so the combustion gases generated in the furnace as well as the turbine gases that bypass the furnace pass thereover, the boiler having steam generating and steam heating surface sufficient to develop the design pressure and temperature at maximum load when the gas turbine is shut down and the boiler is fired With atmospheric air, the steam heating surface, over which the gas turbine gases that bypass the boiler furnace pass, being sufficient to aid the boiler to give this design temperature when operating at maximum load in combination with the gas turbine where gas turbine exhaust gases are employed as the combustion supporting medium for the fuel in the boiler and means to controllably proportion the turbine gases between the boiler furnace and the bypass.

3. In a power plant organization the combination of a vapor generator having a furnace fired with a suitable fuel, a gas turbine engine of the type wherein the amount of turbine exhaust gases remains generally constant over a substantial load range with these exhaust gases providing a substantial excess of oxygen over that required to fire said furnace, means introducing a portion of the turbine exhaust gases into the furnace to support combustion of fuel therewithin, means bypassing said furnace with the remainder of said gases, said vapor generator having economizer surface a portion of which is in said bypass means to absorb heat from the bypassing turbine gases, said vapor generator also having vapor heating surface one section of which is disposed in said bypass before the economizer to absorb heat from the bypassing turbine gases and another section of which is disposed to have the gases from the furnace pass thereover, and means operative to controllably proportion the turbine exhaust gases between the bypass means and the furnace.

References Cited in the file of this patent UNITED STATES PATENTS 1,398,946 Schmidt Nov. 29, 1921 1,925,646 Rakestraw Sept. 5, 1933 2,107,440 Gordon Feb. 8, 1938 2,223,953 Davis Dec. 3, 1940 2,471,755 Karrer May 31, 1949 2,604,755 Nordstrom et a1. July 29, 1952