Patent Application
20120073196
The present invention generally involves a system and method for controlling a gasifier. Specific embodiments of the present invention may include a controller that adjusts conditions in the gasifier to reduce corrosion.
An Integrated Gasification Combined Cycle (IGCC) is known in the art for converting petroleum coke or coal into synthetic gas which may then be supplied to a gas turbine to generate power. The synthetic gas, a clean burning fuel, may be burned directly in the gas turbine or may be processed further to produce methanol and hydrogen for combustion in the gas turbine.
The IGCC typically includes a gasifier to convert the petroleum coke or coal into the synthetic gas. The petroleum coke or coke is partially combusted with oxygen in a gasifier at a high temperature and pressure to produce the synthetic gas. The gasifier may be constructed of an insulated brick lining surrounded by a pressure resistant steel vessel. The brick lining is typically designed to withstand internal gasifier temperatures of approximately 2,500-3,000° F., while the steel vessel is typically designed to withstand an inner surface temperature of approximately 400-600° F.
The gasification process may produce highly corrosive byproducts, such as ammonium chloride. If the dew point of the inner surface of the steel vessel is less than the dew point of the corrosive byproducts, then the corrosive byproducts may condense on an inside surface of the steel vessel, causing aqueous corrosion on the inside surface of the steel vessel. The aqueous corrosion on the inside surface of the steel vessel is undesirable in that it may result in unplanned outages for maintenance and/or repair and ultimately reduces the useful life of the steel vessel.
Various attempts have been made to control the production and/or effects of the corrosive byproducts. For example, attempts have been made to indirectly monitor the production of the synthetic gas, and thus the production of the corrosive byproducts. Other attempts have involved costly external wind deflectors and variations in the design of the brick insulation. However, an improved system and method for controlling the gasifier would be useful in reducing corrosion caused by the corrosive byproducts.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is a gasifier that includes a combustion chamber and a pressure vessel surrounding the combustion chamber, wherein the pressure vessel includes an inner surface. A heater surrounds the pressure vessel and increases a temperature of the inner surface of the pressure vessel.
Another embodiment of the present invention is a gasifier that includes a combustion chamber and a pressure vessel surrounding the combustion chamber, wherein the pressure vessel includes an inner surface. A heater surrounds the pressure vessel, and a controller connected to the heater generates a heater signal to activate the heater.
The present invention also includes a method for operating a gasifier. The method includes increasing an inner wall temperature of a pressure vessel surrounding the gasifier.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
The gasifier 10 may further include separate or combined supplies of fuel 20, oxidants 22, and/or diluents 24 to the combustion chamber 12. The fuel generally comprises petroleum coke, coal, or another suitable product to be gasified. The oxidants generally comprise oxygen, an oxygen compound, or another chemical capable of combusting with the fuel. The diluents generally comprise nitrogen, argon, or another inert gas for diluting the oxidants prior to combustion. The supply of fuel 20, oxidants 22, and/or diluents 24 may comprise any suitable tank, piping, and/or valve system for transporting the fuel, oxidants, or diluents to the gasifier 10. The fuel, oxidants, and/or diluents combine in the combustion chamber 12 to produce the synthetic gas. In addition, the combustion produces one or more byproducts, including corrosive compounds such as ammonium chloride.
As shown in the embodiment illustrated in
The heater 26 may be manually activated or energized as needed to increase the temperature of the inner wall 30 of the pressure vessel 14. For example, measured parameters of the gasifier 10, content of the fuel, production rate of the synthetic gas, or any other operational parameter may be used to determine when to activate or energize the heater 26. In this manner, the temperature of the inner wall 30 of the pressure vessel 14 may be maintained greater than the dew point of any corrosive compound produced during combustion to reduce and/or prevent condensation of the corrosive compound on the inner wall 30 of the pressure vessel 14.
As shown in
The gasifier 10 may further include a corrosion sensor 36 between the pressure vessel 14 and the combustion chamber 12. The corrosion sensor 36 may comprise an electronic circuit that measures a voltage potential or current flow created by the presence of the corrosive compounds on the inner wall 30 of the pressure vessel 14. The corrosion sensor 36 may thus generate a corrosion signal 38 reflective of the presence and/or amount of corrosive compounds present between the pressure vessel 14 and the combustion chamber 12. The corrosion signal 38 may be manually interpreted and acted on by an operator to activate or energize the heater 26, as desired. Alternately, the corrosion sensor 36 may be connected to the controller 32 to transmit the corrosion signal 38 to the controller 32. In this manner, the controller 32 may be programmed to activate or energize the heater 26 upon receiving a predetermined corrosion signal.
One of ordinary skill in the art will readily appreciate that the gasifier 10 shown in
Measured parameters of the gasifier 10, content of the fuel, production rate of the synthetic gas, or any other operational parameter may be used to manually adjust the flow rate of the fuel, oxidants, and/or diluents. For example, the gasification of higher energy fuel generally results in a higher pressure in the combustion chamber 12 and pressure vessel 14. This higher pressure in the combustion chamber 12 and pressure vessel 14 produces a corresponding higher dew point for any corrosive compounds produced as byproducts. The higher dew point for the corrosive compounds may lead to undesirable condensation of the corrosive compounds on the relatively cooler inner wall 30 of the pressure vessel 14. Therefore, the flow of fuel and/or oxidants may be decreased to reduce the pressure in the combustion chamber 14 and produce a corresponding decrease in the dew point of any corrosive compounds produced as byproducts. Alternately, or in addition, the flow rate of the diluents may be increased to raise the dilution of the oxidants prior to combustion, producing a similar increase in the pressure and dew point of any corrosion compounds produced as byproducts.
As shown in
Alternately, or in addition, the corrosion sensor 36 may generate the corrosion signal 38 reflective of the presence and/or amount of corrosive compounds present between the pressure vessel 14 and the combustion chamber 12, as previously described with respect to
One of ordinary skill in the art will readily appreciate that the gasifier 10 shown in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other and examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
