Patent Application
20120222354
This invention relates generally to refractory walls, and gasification devices and methods employing the refractory walls. More particularly, the invention relates to refractory walls and slagging gasification devices and methods employing the refractory walls.
Gasification devices, such as gasifiers, are generally used for gasification of carbonaceous fuels, such as coal, to produce mixtures of hydrogen and carbon monoxide, such as coal gas or synthesis gas. The gasification of coal and other carbon-containing materials produces energy more efficiently and with less environmental impact than some conventional combustion-based processes.
The principle of the gasification of carbonaceous fuels consists in controlled partial combustion under pressures approximately from 1 atmosphere to 200 atmospheres and in a steam or oxygen atmosphere at a temperature approximately from 800° C. to 2000° C. For the coal gasification, the reliability of gasification devices in such severe operation conditions generally depends on the service life and performance of refractory walls used to maintain the gasification.
In some gasification devices, molten or liquid slag is formed during the gasification process. The slag is a corrosive agent that penetrates the refractory walls so as to shorten the service life of the refractory walls. As a result, such gasification devices have to be periodically shut down for replacement of the refractory walls, which reduces the productivity and increases the cost for the carbonaceous gasification.
Therefore, there is a need for new and improved refractory walls and slagging gasification devices and methods employing refractory walls.
A refractory wall is provided in accordance with one embodiment of the invention. The refractory wall comprises a hotface layer comprising a hotface surface configured to be adjacent to a carbonaceous gasification environment, a backing layer facing the hotface layer, and a cooling layer facing the backing layer and configured to cool the hotface layer via the backing layer.
A gasification device for gasification of one or more carbonaceous fuels is provided in accordance with another embodiment of the invention. The gasification device comprises a gasifying apparatus comprising a refractory wall defining a gasification chamber for the gasification. At least a part of the refractory wall comprises a hotface layer comprising a hotface surface configured to define the gasification chamber, a backing layer around the hotface layer, and a cooling layer around the backing layer and configured to cool the hotface layer via the backing layer. The at least a part of the refractory wall further comprises a compressible layer around the cooling layer and a shield around the compressible layer.
Another aspect of the invention further comprises a gasification process that comprises introducing one or more carbonaceous fuels and one or more oxidizing streams into a gasifying apparatus. The gasifying apparatus comprises a refractory wall defining a gasification chamber for the gasification with at least a part of the refractory wall comprising a hotface layer configured to define the gasification chamber, a backing layer around the hotface layer, and a cooling layer around the backing layer. The at least a part of the refractory wall further comprises a compressible layer around the cooling layer. The coal gasification process further comprises gasifying the one or more carbonaceous fuels in the gasifying apparatus to produce at least syngas and slag, and cooling the hotface layer via, the backing layer by the cooling layer so that a portion of the slag deposits on at least a part of the hotface layer.
The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the subsequent detailed description when taken in conjunction with the accompanying drawings in which:
Embodiments of the present disclosure are described herein with reference to the accompanying drawings. In the subsequent description, well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. As used herein “facing” and “around” are not intended to preclude the possibility of additional intermediate layers being present to the extent such layers do not interfere with the functionality of the structural and cooling aspects of the present invention.
As illustrated in
Additionally, in some examples, the gasification device 10 further comprises a cooling apparatus 12 disposed downstream from the gasifying apparatus 11. In the illustrated example, the cooling apparatus 12 is in fluid communication with the lower end of the gasifying apparatus 11 to receive and cool outputs, such as slag and/or syngas from the gasifying apparatus 11. In non-limiting examples, the cooling apparatus 12 may have a cylindrical shape and may include a radiation syngas cooler (RSC) or a cooler with a slag bath, for example.
For the illustrated arrangement, during operation, carbonaceous fuels 13 and one or more oxidizing streams 14 are introduced into the gasifying apparatus 11 from the upper end thereof to perform the gasification process to produce the syngas (not shown) with a by-product of slag 15 (shown in
It should be noted that the arrangement of the gasification device 10 is merely illustrative. In some examples, the gasifying apparatus 11 and the cooling apparatus 12 may be separate units, as shown, and in other examples, the gasifying apparatus 11 and the cooling apparatus 12 may be integrated into a unitary structure. In some applications, the carbonaceous fuels 13 and/or the oxidizing stream 14 may be introduced into the gasifying apparatus 11 from the lower end thereof. In certain applications, the cooling apparatus 12 may not be employed and the syngas may be introduced into a next reactor, such as a fixed-bed reactor for further treatment.
As illustrated in
The backing layer 20 is disposed around and configured to back the hotface layer 19 so as to improve the mechanical strength of the refractory wall 17. In some embodiments, the hotface layer 19 and/or the backing layer 20 may comprise one or more refractory materials. Non-limiting examples of the one or more refractory materials may be selected from the group consisting of ceramics, silicon carbide, silicon nitride, alumina (Al2O3), zirconia (ZrO2), silica (SiO2), magnesia (MgO), chromium-containing materials including chromia (Cr2O3), and combinations thereof. In some examples, bricks used in the hotface layer 19 may comprise one or more chromium-containing materials, such as ZIRCHROM90™ and ZIRCHROM60™ ceramics produced by Saint-Gobain Industrial Ceramics. The backing layer 20 may also comprise one or more chromium-containing materials, such as CHROMCOR12™ ceramics produced by Saint-Gobain Industrial Ceramics.
In some non-limiting examples, the hotface layer 19 may comprise refractory bricks with some extending outward into a first pattern. The backing layer 20 may have a second pattern of extending bricks, which is aligned so that the extending bricks of the backing layer 20 may be inserted into open areas of the hotface layer 19.
The cooling layer 21 is disposed around the backing layer 20 so as to be positioned between the backing layer 20 and the compressible layer 22 to cool the hotface layer 19 and the backing layer 20. Thus, during gasification, the temperatures of the hotface layer 19 and the backing layer 20 may be reduced to offset the effect of the high temperatures in the gasification process so as to increase the service life and performance thereof. In some examples, the cooling layer 21 may employ one or more coolants, such as water and oil for removing the heat from the hotface layer 19 and the backing layer 20. In one non-limiting example, the cooling layer 21 comprises one or more tubes with water circulating therein for cooling the refractory bricks 19 and the backing layer 20.
In some embodiments, the compressible layer 22 is located between the cooling layer 21 and the shield 23 for thermal insulation and buffering of the thermal expansion of the hotface layer 19, the backing layer 20 and/or the cooling layer 21. In some examples, the compressible layer 22 may be resistant to high temperatures and comprise one or more refractory organic materials. In one non-limiting example, the one or more refractory organic materials include one or more ceramic fiber materials or other suitable materials. The shield 23 is disposed outside of the compressible layer 22 to reinforce the mechanical integrity of the gasification device 10 and sustain the pressure differences between the inside and the outside of the gasification device 10. In some examples, the shield 23 may comprise one or more metal materials, such as stainless steel. In certain applications, the compressible layer 22 and/or the shield 23 may not be employed.
Accordingly, as depicted in
Meanwhile, the cooling layer 21 cools the hotface layer 19 via cooling the backing layer 20. Due to the cooling of the cooling layer 21, a portion of the slag 15 solidifies or becomes viscous so as to deposit on the hotface surface 16 of the hotface layer 19. As a result, the deposited slag layer 24 on the hotface layer 19 prevents other fluid slag from corroding the refractory wall 17. In certain examples, the step of cooling the hotface layer 19 and the step of gasifying the fuels may be performed simultaneously.
Thus, the refractory wall 17 may be protected in presence of deposited slag layer 24. In some applications, the deposited slag layer 24 may be formed as a portion of the refractory wall 17 and act as a hotface layer, in a similar manner as the hotface layer 19 for subsequent gasification processes. Additionally, as described before, the cooling layer 21 may reduce the temperatures of the hotface layer 19 and the backing layer 20 so that the refractory wall 17 may also be protected from corrosion of the high temperatures.
In embodiments of the invention, the cooling layer 21 may reduce the temperature of the refractory wall 17 and facilitate the deposition of the slag layer 24 on the refractory wall 17. Thus, the service life and the performance of the gasification device 10 may be increased to enhance the productivity thereof, Additionally, in certain applications, the arrangements of the refractory wall 17 may be used to retrofit conventional gasifiers to improve their performances.
While the disclosure has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present disclosure. As such, further modifications and equivalents of the disclosure herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be through the spirit and scope of the disclosure as defined by the subsequent claims.
