Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
1999-06-10
2001-07-10
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
Reexamination Certificate
active
06256978
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a combination power plant with a gas turbine with a generator and with steam generators for a mixed-pressure steam turbine with a generator, wherein the exhaust gas of the gas turbine is fed to a first waste heat boiler with heating surfaces for feed water preheating, steam generation and steam superheating and flue gases of a thermal conversion unit are fed to a second waste heat boiler.
BACKGROUND OF THE INVENTION
The utilization ofthe low-temperature waste heat of flue gases from thermal conversion processes for power generation has failed hitherto because of the low economic efficiency of the units operating in tandem.
The relatively low exhaust gas temperatures of these waste heat sources, which are subject to great variations due to the process, made possible only low steam parameters before. The electric efficiency of the power generation in a generator in cooperation with a steam turbine was characterized by measures to reach a suitable steam temperature and steam pressure.
A combination power plant with a gas turbine power plant and with a steam power plant has been known from DE 195 23 062 A1.
In this combination power plant with a gas turbine power plant and with a steam power plant, a steam turbine plant is operated with the steam of a steam generator equipped with firing equipment and/or with the steam of a waste heat boiler, through which the exhaust gas of the gas turbine flows. A heat exchanger is provided for the controllable preheating of the compressed combustion air of the gas turbine plant. To operate the combination power plant especially economically even in partial load operation, the heat exchanger for the combustion air of the gas turbine plant is arranged in the flue gas duct of the steam generator and is designed as a recuperator, wherein the flue gas is led around the pipes of the recuperator and the combustion air is led though the pipes ofthe recuperator. The recuperator is connected via a three-way valve and a bypass to the combustion air line leading from the compressor to the gas burner of the gas turbine plant.
A thermal power plant with a gas turbine and with a steam generator for a multi-pressure steam turbine has been known from the yet unpublished DE 197 34 862.9, wherein the exhaust gas of the gas turbine is fed to a waste heat boiler, which is equipped with auxiliary firing equipment to raise the high pressure (HP) steam output and which contains heat exchangers intended for generating steam. To make it possible to generate steam economically for a multi-pressure steam turbine, especially also at varying loads, three series-connected HP superheater stages with two spray coolers are provided for generating high-pressure steam, and two intermediate-pressure (IP) superheater stages with a spray cooler are provided for generating an intermediate-pressure (IP) steam. The end stages of the HP superheater and IP superheater are arranged in the same section ofthe waste heat boiler, and their tubes are located alternatingly next to one another in a comb-like pattern. The first IP superheater stage is located between or behind the first two HP superheater stages. A first firing equipment utilizing the exhaust gas of the gas turbine is arranged in the area of the end stages of the superheaters, and a second firing equipment is arranged in front ofthe HP evaporator, wherein the first firing equipment is controlled as a function of the temperature of the steam at the outlet of the first IP superheater stage, and the second firing equipment is controlled by the HP load in a pressure-dependent manner.
SUMMARY AND OBJECTS OF THE INVENTION
The object ofthe present invention is to design the power generation in a combination power plant with a gas turbine and steam turbine such that low-temperature waste heat of flue gases from thermal conversion processes, e.g., waste incinerator plants and similar processes are used to generate steam and the entire process is economically better utilized due to the utilization of the waste heat of flue gases.
The low-temperature waste heat of flue gases from thermal conversion processes, e.g., in the manufacture of cement and limestone, iron ore-sintering plants, in steel-making, in waste incineration and other similar processes are first fed according to the present invention into a so-called process waste heat boiler before the flue gases enter a scrubbing stage and then enter the atmosphere in the purified and cooled state.
High heat utilization takes place in the process waste heat boiler due to the installation of a high pressure (HP) evaporator and of a low-pressure (LP) evaporator system.
To avoid condensation, both steam flows are passed over the supporting tubes of the respective evaporator systems and are superheated. This superheated HP steam is mixed via a connection line with the steam generated in the waste heat boiler on the gas turbine exhaust gas side.
The two amounts of steam are superheated together to the desired steam temperature in the superheaters of the gas turbine waste heat boiler, there being at least two superheaters. The superheated steam enters the high-pressure stage ofthe steam turbine via a connection line.
Via an LP drum and via the connection lines, the LP steam generated in the process waste heat boiler enters the feed water tank, where thermal degassing takes place. The rest of the LP steam enters the LP stage of the steam turbine via a connection line. The flue gas-side pressure losses are overcome by the downstream induced-draft blower integrated within the process.
The feed water preheating takes place in a common economizer at the end of the gas turbine waste heat boiler. The amounts of feed water are split between the respective HP drums via a three-way valve.
The feed water is cooled by the condensate arriving from the condenser by an external water-water heat exchanger to the extent that a very high waste heat utilization is possible in the gas turbine waste heat boiler with the low water inlet temperature now occurring at the HP economizer.
The power generation takes place in the generator of the gas turbine with a DLN combustion chamber and in the generator of the multi-pressure steam turbine.
In the case of failure of the gas turbine, the waste heat boiler operates in the so-called simulated waste heat operation. A fresh air blower then delivers such an amount of air into the waste heat boiler that the same amount of exhaust gas is present as in the case of the gas turbine operation.
Auxiliary burner systems at the inlet ofthe waste heat boiler now heat the cold air to the extent that the required steam conditions are reached.
The combination power plant according to the present invention combines the waste heat utilization on the process exhaust gas side with a subsequent slight preheating via an HP and LP evaporator.
The full superheating of the steam takes place on the gas turbine exhaust gas side via a superheater divided into two parts as well as an HP evaporator and a common HP economizer. The HP economizer feeds both the HP evaporator on the gas turbine exhaust gas side and the HP evaporator on the flue gas side of the thermal conversion unit. Power generation with a high overall electric efficiency is possible due to high waste heat utilization on the gas turbine exhaust gas side.
Part of the LP steam is used for thermal degassing, the rest being used for power generation, and the steam pressure and the steam temperature are determined extensively by the process gas data.
The drawbacks of prior-art plant circuits arise from the following facts:
Power generation from purely low-temperature waste heat limits the electric efficiency;
An increase in the gas temperature before the waste heat steam generator is achieved by means of auxiliary firing equipment on the flue gas side of the thermal conversion unit, and this increase in the gas temperature leads to the generation of a larger amount of power, but it entails greater energy losses and exhaust gas losses (additional amount of flue gas);
The softening point
Faustmann Norbert
Gericke Bernd
Hansen Ole
Jeske Hans-O.
GHH Borsig Turbomaschinen GmbH
McGlew and Tuttle , P.C.
Rodriquez William H
Thorpe Timothy S.
LandOfFree
Power generation in a combination power plant with a gas... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power generation in a combination power plant with a gas..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power generation in a combination power plant with a gas... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513824