Gas: heating and illuminating – Generators – Cupola
Reexamination Certificate
2000-08-08
2003-11-18
Johnson, Jerry D. (Department: 1764)
Gas: heating and illuminating
Generators
Cupola
C048S063000, C048S075000, C048S077000, C048S089000, C048S107000, C048S119000, C060S039120, C422S186220, C422S186220, C422S198000, C422S199000
Reexamination Certificate
active
06648931
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is an improved configuration and process for gasification of carbonaceous materials.
BACKGROUND OF THE INVENTION
Many processes for the production of power, hydrocarbons, and ammonia employ a gasification or partial oxidation unit. While some of the gasification or partial oxidation units are oxygen blown (e.g., by rerouting a stream of purified oxygen from an air separation unit to the gasifier), other gasification or partial oxidation units are air blown. In addition to the stream of air that delivers oxygen for the oxidation of the feedstock in air-blown gasifiers, steam is frequently introduced into the gasification or partial oxidation unit to control the process temperature, and in some cases, to provide a source of hydrogen.
Steam for an air-blown gasification or partial oxidation unit is typically generated in a steam generator driven by a high-temperature heat source. Since the steam demand in most gasification or partial oxidation units is considerable, production of steam employing high-temperature heat sources often leads to a significant decrease in thermal efficiency of the power or gas generation plant. Moreover, many steam generators require de-mineralized water to prevent calcification and build-up of other non-volatile components.
To increase the thermal efficiency of power and/or gas generation plants, various approaches have been developed. For example, in one approach described in U.S. Pat. No. 3,818,869 to Blaskowski, a portion of the low-Btu gas from a gasification unit is employed to fire a steam generator, and heat from the gasifier is further delivered to the steam generator feed water. Although the use of the low-Btu gas as an energy source for steam generation improves the thermal efficiency at least to some extent in this particular configuration, the generation of steam nevertheless requires significant amounts of thermal energy.
In another approach, Johnson et al. teach in U.S. Pat. No 5,695,532 the use of particulate solid carbonaceous fuel with high moisture content, in which the water contained in the feedstock evaporates within the gasification unit to produce the steam required in the gasification process. Johnson's system advantageously eliminates or at least greatly reduces the need to generate and introduce steam into the gasification unit. However, in order to maintain efficient gasification, the moisture content of the feedstock needs to be adjusted to a level suitable for gasification, thereby requiring additional process steps and drying facilities. Moreover, Johnson's process is generally limited to solid carbonaceous feedstock.
Although various modifications to gasification plant configuration and processes to improve thermal efficiency have been developed, all or almost all of them suffer from one or more disadvantages. Therefore, there is a need for an improved configuration and process for gasification of carbonaceous material.
SUMMARY OF THE INVENTION
The present invention is directed to an improved configuration and process for gasification of carbonaceous materials, in which humidified air is introduced into a gasification/partial oxidation vessel. The humidified air is generated via a turbine that produces a stream of pressurized air, which is subsequently cooled by a cooler. A booster further compresses the cooled pressurized air, and a humidifier humidifies the stream of cooled compressed air. A low temperature heat source provides heat for the humidifier, and the humidified air is preheated before introduction into the gasification vessel. It is generally preferred that the turbine comprises a gas turbine and the booster compresses the pressurized air to a pressure of 300 to 400 psi or less.
In one aspect of the inventive subject matter, the gasification vessel is part of an integrated gasification combined cycle facility (IGCC). The gasification vessel may be utilized to gasify a feedstock in a fixed-bed process, a fluidized-bed process, or an entrained-flow process, and may alternatively be employed in a partial oxidation process. While preferred feedstock of the gasification process comprises oil, coke, coal, liquid and/or solid hydrocarbon containing material, the feedstock for partial oxidation preferably comprises hydrocarbons.
In another aspect of the inventive subject matter, the humidifier utilizes wastewater to humidify the cooled compressed air, and it is preferred that the humidifier employs a counter current flow of water, wherein the wastewater is preferably produced by a component of the gasification plant. Especially contemplated humidifiers include a water circulation loop that includes a water heater operationally coupled to the water circulation loop wherein the water heater advantageously comprises a heat exchanger or a low-Btu gas cooler.
Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawing.
REFERENCES:
patent: 4150953 (1979-04-01), Woodmansee
patent: 4976549 (1990-12-01), Khan
patent: 5398663 (1995-03-01), Kulasinghe
Doroshenk Alexa Ann
Fluor Corporation
Johnson Jerry D.
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