Method for providing auxiliary power to an electric power plant using fischer-tropsch technology

Abstract

A method for meeting both base-load and peak-load demand in a power production facility. By integrating a Fischer-Tropsch (FT) hydrocarbon production facility with an electrical power generating facility, peak-load power demand can be met by reducing the temperature of the FT reactor thereby increasing the quantity of tail gases and using FT tail gases to fuel a gas turbine generator set. The method enables rapid power response and allows the synthesis gas generating units and the FT units to operate with constant flow rates.

1 . A system for providing peak-load electrical demand for a gas turbine driven power generating unit, said system comprising:
 a gas turbine driven power generating unit integrated with a hydrocarbon production facility comprising at least one Fischer-Tropsch (FT) unit;   said hydrocarbon production facility further comprising a gasification unit and a gas purification unit;   wherein said gasification unit is operable under constant conditions to react feedstock, oxygen and steam for producing a continuous flow of synthesis gas comprising primarily hydrogen and carbon monoxide;   wherein said gas purification unit is operable to remove sulfur and other impurities from said synthesis gas, thereby forming a continuous flow of cleaned synthesis gas;   wherein said at least one FT unit has an inlet for a continuous inflow of a portion of said cleaned synthesis gas, an outlet for a synthesis gas-laden FT tail gas comprising unconverted synthesis gas and gaseous hydrocarbons, an outlet for liquid hydrocarbons, an outlet for naphtha, and is operable at a decreased rate of reaction;   wherein the gas turbine driven power generating unit is fueled with the synthesis gas-laden FT tail gas to provide peak electrical power.   
     
     
         2 . The system of  claim 1 , wherein the gasifier feedstock is carbonaceous. 
     
     
         3 . The system of  claim 1 , wherein the gasifier feedstock is selected from the group consisting of coal, petroleum coke, saw dust, sewage sludge, agricultural waste, and an energy crop. 
     
     
         4 . The system of  claim 1 , wherein said hydrocarbon production facility further comprises a feedstock preparation unit adapted to convert feedstock into a pumpable slurry. 
     
     
         5 . The system of  claim 1 , wherein the at least one FT unit comprises a catalyst to promote the formation of predominantly hydrocarbons having more than five carbon atoms, said catalyst being selected from the group consisting of iron, cobalt, nickel, and ruthenium. 
     
     
         6 . The system of  claim 1 , wherein said at least one FT unit further comprises cooling coils housed in said at least one FT unit whereby said rate of reaction may be decreased. 
     
     
         7 . The system of  claim 1 , wherein said at least one FT unit further comprises a water/steam coolant housed in said at least one FT unit whereby heat transfer from a FT slurry may be increased to obtain said decreased rate of reaction. 
     
     
         8 . The system of  claim 1 , wherein the at least one FT unit is operable at varying temperatures, whereby the amount of FT tail gas fueling the gas turbine power generating unit is adjustable for varying peak electrical power generation. 
     
     
         9 . The system of  claim 8 , wherein the at least one FT unit is operable at temperatures from about 190° C. to about 275° C. 
     
     
         10 . The system of  claim 1  further comprising a tail gas recycle from the at least one FT unit tail gas outlet to an inlet of the at least one FT unit, whereby a percentage of FT tail gas may be recycled to the at least one FT unit during non-peak hours. 
     
     
         11 . The system of  claim 10 , wherein said percentage of tail gas recycled to the inlet of the at least one FT unit during non-peak hours ranges from about 30% to about 90%. 
     
     
         12 . The system of  claim 1  further comprising a combined cycle power production unit fueled with a portion of said cleaned synthesis gas, thereby generating electrical power for base-load requirements. 
     
     
         13 . The system of  claim 12 , wherein said combined cycle power production unit is further fueled with a portion of said synthesis gas-laden FT tail gas for base-load requirements. 
     
     
         14 . The system of  claim 1 , wherein said hydrocarbon production facility further comprises an air separation unit for producing a stream of oxygen for use in said gasification unit. 
     
     
         15 . A system for smoothing out fluctuating power produced by a power production facility which is subject to wide variability in energy source, said system comprising:
 a power production facility integrated with one or more gas turbine-generator sets and a hydrocarbon production facility comprising at least one Fischer-Tropsch (FT) reactor;   said hydrocarbon production facility further comprising a gasification unit and a gas purification unit;   wherein said gasification unit is operable under constant conditions to react feedstock, oxygen and steam for producing a continuous flow of synthesis gas comprising primarily hydrogen and carbon monoxide;   wherein said gas purification unit is operable to remove sulfur and other impurities from said synthesis gas, thereby forming a continuous flow of cleaned synthesis gas;   wherein said at least one FT reactor has an inlet for a continuous inflow of a portion of said cleaned synthesis gas and is operable at a decreased rate of reaction, an outlet for a synthesis gas-laden FT tail gas comprising unconverted synthesis gas and gaseous hydrocarbons, an outlet for liquid hydrocarbons, and an outlet for naphtha;   wherein the one or more gas turbine-generator sets are fueled with a portion of said cleaned synthesis gas and the synthesis gas-laden FT tail gas to provide base electrical power, thereby smoothing out power production over time.   
     
     
         16 . The system of  claim 15 , wherein said power production facility comprises at least one electrical power generator powered by wind turbine. 
     
     
         17 . The system of  claim 15 , wherein said power production facility comprises at least one electrical power generator powered by solar cells. 
     
     
         18 . The system of  claim 15 , wherein said hydrocarbon production facility further comprises a feedstock preparation unit to convert feedstock into a pumpable slurry. 
     
     
         19 . The system of  claim 15 , wherein the gasifier feedstock is carbon-bearing. 
     
     
         20 . The system of  claim 15 , wherein the gasifier feedstock is selected from the group consisting of coal, petroleum coke, saw dust, sewage sludge, agricultural waste, and an energy crop. 
     
     
         21 . The system of  claim 15 , wherein said at least one FT reactor comprises a catalyst to promote the formation of predominantly hydrocarbons having more than five carbon atoms, said catalyst being selected from the group consisting of iron, cobalt, nickel, and ruthenium. 
     
     
         22 . The system of  claim 15 , wherein said at least one FT unit further comprises cooling coils housed in said at least one FT unit whereby said rate of reaction may be decreased. 
     
     
         23 . The system of  claim 15 , wherein said at least one FT reactor further comprises a water/steam coolant housed in said at least one FT reactor whereby heat transfer from a FT slurry may be increased to obtain said decreased rate of reaction. 
     
     
         24 . The system of  claim 15 , wherein the at least one FT reactor is operable at varying temperatures, whereby the amount of FT tail gas fueling the gas turbine power generating unit is adjustable for varying base power requirements. 
     
     
         25 . The system of  claim 15 , wherein the at least one FT reactor is operable at temperatures from about 190° C. to about 275° C. 
     
     
         26 . The system of  claim 15 , wherein said hydrocarbon production facility further comprises an air separation unit for producing a stream of oxygen for use in said gasification unit. 
     
     
         27 . A process for meeting base-load and peak-load electrical requirements, said method comprising the steps of:
 integrating a gas turbine-generator set and a combined cycle power production unit with a hydrocarbon production facility comprising one or more Fischer-Tropsch (FT) reactors and one or more gasification units;   introducing a carbonaceous feedstock, oxygen and steam into the one or more gasification unit to produce a constant supply of synthesis gas comprising primarily hydrogen and carbon monoxide;   removing sulfur and other impurities from said synthesis gas, thereby forming a cleaned synthesis gas;   fueling said one or more FT reactors with a constant flow rate of a first portion of said cleaned synthesis gas, thereby forming liquid hydrocarbons, naphtha and a FT tail gas comprising unconverted synthesis gas and gaseous hydrocarbons,   providing base-load requirements to a gas turbine of the combined cycle power production unit by introducing a second portion of the cleaned synthesis gas or a second portion of the cleaned synthesis gas and a portion of the FT tail gas into the gas turbine of the combined cycle power production unit;   providing peak-load requirements by decreasing the temperature of the one or more FT reactors to a temperature below the operating temperature during base-load operation, thereby causing an increased amount of unconverted synthesis gas to be present in the FT tail gas, and fueling the gas turbine-generator set with at least a portion of the FT tail gas rich in unconverted synthesis gas,   wherein the flow rate of the cleaned synthesis gas to the one or more FT reactors is constant during base-load and peak-load operation.