The Southern Company

Southern Company Services, Inc.

Pannalal Vimalchand

Guohai Liu

WanWang Peng

Wan Wang Peng

Alexander K Bonsu

Xiaofeng Guan

Wanwang Peng

A method and apparatus for cooling hot gas streams in the temperature range 800&#xb0; C. to 1600&#xb0; C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers.

Multi-stage circulating fluidized bed syngas cooling

A method and apparatus for cooling hot gas streams in the temperature range 800&#xb0; C. to 1600&#xb0; C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

A coal feed system to feed pulverized low rank coals containing up to 25 wt % moisture to gasifiers operating up to 1000 psig pressure is described. The system includes gas distributor and collector gas permeable pipes imbedded in the lock vessel. Different methods of operation of the feed system are disclosed to minimize feed problems associated with bridging and packing of the pulverized coal. The method of maintaining the feed system and feeder device exit pressures using gas addition or extraction with the pressure control device is also described.

High pressure feeder and method of operating to feed granular or fine materials

Disclosed are cooling and depressurization system equipment, arrangement and methods to cool solid particles from a coal gasifier operating at high temperature and pressure. Ash needs to be continuously withdrawn from a circulating fluidized bed gasifier to maintain the solids inventory in the gasifier. The supports for the cooling surfaces are located on the lower temperature upper section of the primary cooler. The cooled solids along with the fluidizing gas exits the primary cooler to a secondary receiving vessel where the solids can be further cooled by conventional means. The fluidizing and entrained gas entering the secondary vessel is filtered and vented through a vent pressure control valve. The column of cooled solids in the secondary vessel is depressurized by a continuous depressurization system to low pressures which are sufficient for conveying the solids to silos for disposal.

Ash and solids cooling in high temperature and high pressure environment

An apparatus to promote gas-liquid contact and facilitate enhanced mass transfer. The dispersed bubble reactor (DBR) operates in the dispersed bubble flow regime to selectively absorb gas phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet gas bubbles into fine bubbles with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the riser to facilitate annular flow. While the DBR can absorb COin liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with gas and liquid phases.

Dispersed bubble reactor for enhanced gas-liquid-solids contact and mass transfer

This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150&#xb0; C. to 1500&#xb0; C. range as well as in excess of 1500&#xb0; C. In a preferred embodiment, such coals are dealt with a two stage gasification process&#x2014;a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

Gasification of high ash, high ash fusion temperature bituminous coals

A second stage gasification unit in a staged gasification integrated process flow scheme and operating methods are disclosed to gasify a wide range of low reactivity fuels. The inclusion of second stage gasification unit operating at high temperatures closer to ash fusion temperatures in the bed provides sufficient flexibility in unit configurations, operating conditions and methods to achieve an overall carbon conversion of over 95% for low reactivity materials such as bituminous and anthracite coals, petroleum residues and coke. The second stage gasification unit includes a stationary fluidized bed gasifier operating with a sufficiently turbulent bed of predefined inert bed material with lean char carbon content. The second stage gasifier fluidized bed is operated at relatively high temperatures up to 1400&#xb0; C. Steam and oxidant mixture can be injected to further increase the freeboard region operating temperature in the range of approximately from 50 to 100&#xb0; C. above the bed temperature.

Second stage gasifier in staged gasification and integrated process

A regenerator that can handle rich loaded chemical solvent containing precipitated absorption reaction products is disclosed. The invention is particularly suitable for separating COfrom large gas streams that are typical of power plant processes. The internally circulating liquid stream in the regenerator (ICLS regenerator) rapidly heats-up the in-coming rich solvent stream in a downcomer standpipe as well as decreases the overall concentration of COin the mixed stream. Both these actions lead to dissolution of precipitates. Any remaining precipitate further dissolves as heat is transferred to the mixed solution with an inverted bayonet tube heat exchanger in the riser portion of the regenerator. The evolving CObubbles in the riser portion of the regenerator lead to substantial gas hold-up and the large density difference between the solutions in the downcomer standpipe and riser portions promotes internal circulation of the liquid stream in the regenerator. As minor amounts of solvent components present in the exit gas stream are condensed and returned back to the regenerator, pure COgas stream exits the disclosed regenerator and condenser system.

Apparatus and methods for regeneration of precipitating solvent

The improvements proposed in this invention provide a reliable apparatus and method to gasify low rank coals in a class of pressurized circulating fluidized bed reactors termed 'transport gasifier.' The embodiments overcome a number of operability and reliability problems with existing gasifiers. The systems and methods address issues related to distribution of gasification agent without the use of internals, management of heat release to avoid any agglomeration and clinker formation, specific design of bends to withstand the highly erosive environment due to high solid particles circulation rates, design of a standpipe cyclone to withstand high temperature gasification environment, compact design of seal-leg that can handle high mass solids flux, design of nozzles that eliminate plugging, uniform aeration of large diameter Standpipe, oxidant injection at the cyclone exits to effectively modulate gasifier exit temperature and reduction in overall height of the gasifier with a modified non-mechanical valve.

Apparatus, components and operating methods for circulating fluidized bed transport gasifiers and reactors

A pressurized transport oxy-combustor with different configurations is disclosed. Substantially pure oxygen is fed to the transport oxy-combustor under pressure to combust fossil fuels, generating steam for power generation. The end product is the flue gas containing substantially pure COafter moisture condensation. The low excess oxygen necessary to achieve complete combustion in the combustor is scavenged by adding another fuel so that substantially all oxygen fed to the combustor is completely consumed. The capability to operate the transport oxy-combustor as a circulating fluidized bed combustor at very high solids circulation rates makes it unnecessary to use recycled COor flue gas as a means to moderate and control the combustion temperature. The temperature in the combustor is effectively controlled by relatively cooler circulating solids that enter the combustion zone. A small amount of COis recycled for aeration and to convey solids fuel to the combustor.

Oxycombustion in transport oxy-combustor

A system for depressurizing and cooling a high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein. In one aspect, the system has an apparatus for at least partially depressurizing and cooling the high pressure, high temperature dense phase solids stream having gas entrained therein and a pressure letdown device for further depressurization and separating cooled coarse solid particles from a portion of the entrained gas, resulting in a lower temperature, lower pressure outlet of solid particles for downstream processing or discharge to a storage silo for future use and/or disposal. There are no moving parts in the flow path of the solids stream in the system.

Continuous coarse ash depressurization system

Disclosed are apparatus and method to treat large amounts of flue gas from a pulverized coal combustion power plant. The flue gas is contacted with solid sorbents to selectively absorb CO, which is then released as a nearly pure COgas stream upon regeneration at higher temperature. The method is capable of handling the necessary sorbent circulation rates of tens of millions of lbs/hr to separate COfrom a power plant's flue gas stream. Because pressurizing large amounts of flue gas is cost prohibitive, the method of this invention minimizes the overall pressure drop in the absorption section to less than 25 inches of water column. The internal circulation of sorbent within the absorber assembly in the proposed method not only minimizes temperature increases in the absorber to less than 25&#xb0; F., but also increases the COconcentration in the sorbent to near saturation levels. Saturating the sorbent with COin the absorber section minimizes the heat energy needed for sorbent regeneration. The commercial embodiments of the proposed method can be optimized for sorbents with slower or faster absorption kinetics, low or high heat release rates, low or high saturation capacities and slower or faster regeneration kinetics.

Carbon dioxide absorber and regeneration assemblies useful for power plant flue gas

A system for depressurizing and cooling a high pressure, high temperature fine solid particles stream having entrained gas therein. In one aspect, the system has an apparatus for cooling the high pressure, high temperature fine solid particles stream having entrained gas therein and a pressure letdown device for depressurization by separating the cooled fine solid particles from a portion of the fine solid particles stream having entrained gas therein, resulting in a lower temperature, lower pressure outlet of solid particles for disposal or handling by downstream equipment.

Continuous fine ash depressurization system

The system of the present invention includes a centripetal cyclone for separating particulate material from a particulate laden gas solids stream. The cyclone includes a housing defining a conduit extending between an upstream inlet and a downstream outlet. In operation, when a particulate laden gas-solids stream passes through the upstream housing inlet, the particulate laden gas-solids stream is directed through the conduit and at least a portion of the solids in the particulate laden gas-solids stream are subjected to a centripetal force within the conduit.

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Birmingham, AL, United States of America

Pannalal Vimalchand