United States Patent: 4099383

We've documented a number of times, over the long course of our reportage, that it is perfectly feasible to co-generate both hydrocarbon fuels or chemicals of various sorts and electrical power, in the same industrial facility, from Coal.

Such "co-generation" facilities rely on indirect methods of converting Coal into hydrocarbons, wherein Coal is first gasified, through a process of partial oxidation, or limited combustion, and made to form a blend of Carbon Monoxide and Hydrogen, that is, "synthesis gas", or "syngas", which syngas can be chemically, catalytically condensed, as via the long-known Fischer-Tropsch synthesis for just one example, into a full range of both liquid and gaseous hydrocarbons.

 

And, there are multiple ways by which electricity can be co-generated in such Coal conversion plants.

Perhaps most directly, and as represented by the technology disclosed by a long-time practitioner of indirect Coal conversion technology, as seen in our report of;

Eastman Chemical Coal to Liquid Fuel, Chemicals and Electricity | Research & Development | News; concerning, only in part: "United States Patent Application 20060149423 - Method for Satisfying Variable Power Demand; 2006; Inventors: Scott Barnicki, et. al., TN; Correspondence (and presumed eventual Assignee of Rights): Eastman Chemical Company, TN; Abstract: A process for satisfying variable power demand and a method for maximizing the monetary value of a synthesis gas stream are disclosed. One or more synthesis gas streams are produced by gasification of carbonaceous materials and passed to a power producing zone to produce electrical power during a period of peak power demand or to a chemical producing zone to produce chemicals such as, for example, methanol, during a period of off-peak power demand. The power-producing zone and the chemical-production zone which are operated cyclically and substantially out of phase in which one or more of the combustion turbines are shut down during a period of off-peak power demand and the syngas fuel diverted to the chemical producing zone. This out of phase cyclical operational mode allows for the power producing zone to maximize electricity output with the high thermodynamic efficiency and for the chemical producing zone to maximize chemical production with the high stoichiometric efficiency. The economic potential of the combined power and chemical producing zones is enhanced";

a portion of the combustible syngas generated from Coal, and intended for the synthesis of fuel alcohol Methanol, can instead be directed into a "combustion turbine" for the generation of electricity during periods of peak power demand.

Other, perhaps less-direct and less-obvious, options also exist for such co-generation of fuels and electricity from Coal, as seen for example in our report of:

September, 2012, Coal and CO2 to Liquid Fuel and Electric Power | Research & Development | News; concerning; "United States Patent 8,268,896 - Co-production of Fuels, Chemicals and Electric Power; 2012;
Assignee: Gas Technology Institute, Des Plaines, IL; Abstract: A method and system for co-production of electric power, fuel, and chemicals in which a synthesis gas at a first pressure is expanded using a stand-alone mechanical expander or a partial oxidation gas turbine, simultaneously producing electric power and an expanded synthesis gas at a second pressure after which the expanded synthesis gas is converted to a fuel and/or a chemical";

wherein the heat generated by the Coal gasification process itself creates pressure in the product syngas; and, the pressurized syngas can be passed directly through a "turbine" to generate electricity, before being directed into catalyst zone and "converted to a fuel and/or a chemical".

The two closely-related technologies we bring to you herein are of that sort, wherein heat energy generated by the Coal gasification process, which heat is contained in the hot synthesis gas, is extracted by various means and utilized to drive turbines for the generation of electricity.

And, these two related processes originate from a once well-known operator and supplier of American gasoline service stations, the former Texaco, which was assimilated into the Chevron corporation in 2001, with some of their retail assets being divested at that time to Shell.  

We have, of course, many times documented the development, by the former Texaco, of a wide range of Coal utilization and conversion technologies, as, for two examples, seen in our reports of:

Texaco CO2 + Coal = Hydrocarbon Synthesis Gas | Research & Development | News; concerning: "United States Patent 3,976,442 - Synthesis Gas from Gaseous CO2-Solid Carbonaceous Fuel Feeds; 1976; Inventors: Peter Paull, CT, and Warren Schlinger, CA; Assignee: Texaco, Incorporated, NY; Abstract: This is an improved continuous partial oxidation process for producing synthesis gas or fuel gas from gaseous CO2 (and) solid carbonaceous fuel feeds. A solid carbonaceous fuel such as finely ground coal ... is passed directly into a high pressure high velocity CO2 -rich gas stream which carries the particles of coal into a free-flow non-catalytic gas generator where by the partial oxidation reaction with a free-oxygen containing gas, preferably in the absence of supplemental H2O other than that normally present in the reactants, gaseous mixtures principally comprising H2, CO, CO2, and H2O are produced. A CO2 -rich gas stream is recovered downstream in the process and recycled to the pressurized feed system. ... (And) wherein said solid carbonaceous fuel is selected from the group consisting of coal, coke from coal, char from coal, ... lignite, rubber, rubber tires, and mixtures thereof. ... Coal is the most promising raw material in the USA for the production of synthetic natural gas (SNG) and synthesis gas"; and:

Texaco 1976 Coal + CO2 = Hydrocarbon Synthesis Gas | Research & Development | News; concerning: "United States Patent 3,976,443 - Synthesis Gas from Solid Carbonaceous Fuel; 1976; Inventors: Peter Paull, CT, and Warren Schlinger, CA; (Assignee: Texaco); Abstract: This is an improved continuous partial oxidation process for producing synthesis gas or fuel gas from a solid carbonaceous fuel. Liquid CO2 and a ground solid carbonaceous fuel such as coal are mixed together to produce a pumpable slurry feed. The CO2 serves as a carrier for the carbonaceous fuel and as a temperature moderator, and is preferably obtained by purifying the product gas. ... The process ... wherein the weight ratio of CO2 to carbonaceous fuel ... is in the range of about 0.6 to 2.0. The process ... wherein said solid carbonaceous fuel is selected from the group consisting of coal, coke from coal, char from coal, ... particulate carbon soot, ... lignite, rubber, rubber tires and mixtures thereof. ... This invention relates to a continuous process for the production of a CO-rich gas stream by the partial oxidation of a carbonaceous fuel. ...Oil embargoes coupled with already developing petroleum shortages have led to an energy crisis in this country (and) long-term solutions demand that alternate energy resources be developed and utilized to the maximum degree. Coal is the most promising raw material in the USA for the production of synthetic natural gas (SNG) and synthesis gas i.e. mixtures of CO+H2. In the U.S. in 1970 the estimated recoverable coal reserves assuming 50 percent recovery were about 778 billion short tons. In comparison in the U.S. in 1974 the proved reserves of crude oil amounted to about 35 billion barrels. The present invention pertains to an improved continuous partial oxidation process for producing gas mixtures containing for example H2 and CO starting with slurries of liquid CO2 and solid particles of carbonaceous fuel".

Note, in the above Texaco disclosures, the potentials for directly using both CO2 and Carbon-recycling organic wastes, "rubber tires", in the Coal gasification process.

We selected the two above examples of Texaco technology since they were developed by, as the lead named inventor, the accomplished Coal gasification scientist Peter Paull, who is also the lead-named inventor of the two Texaco technologies we report to you in this dispatch, wherein we see further explained how electricity can be co-produced in a process directed, primarily, to the indirect synthesis of hydrocarbon fuels in a process that starts with the gasification of Coal.

First, as excerpted from the initial link in this dispatch, we have:

"United States Patent 4,099,383 - Partial Oxidation Process

Partial oxidation process - Texaco Inc.

Date: July 11, 1978

Inventors: Peter Paull, CT, and Rodney McGann, CA

Assignee: Texaco, Inc., NY

Abstract: Sensible heat in the hot effluent gas stream leaving a partial oxidation gas generator for the production of gaseous mixtures comprising H2 +CO, i.e. synthesis gas, reducing gas, or fuel gas, is used at maximum temperature to heat a stream of heat transfer fluid preferably comprising a portion of the product gas circulating in a substantially closed loop. The heat transfer fluid serves as the working fluid in a turbine that produces mechanical work, electrical energy, or both. Further, the heat transfer fluid leaving the turbine may be used to preheat hydrocarbonaceous feed and free-oxygen containing gas which is then introduced into the gas generator. Optionally, by-product superheated steam may be produced at high temperature levels for use in the gas generator and as the working fluid in an expansion turbine. The high steam superheat temperatures results in higher conversion efficiencies.

(For a number of reasons, primarily a desire for conservation, we prefer technologies like these, where heat generated intrinsically in the gasification process is extracted from the process and used for the generation of electricity, as opposed to those which simply combust a portion of the syngas, as in our above-cited report concerning "United States Patent Application 20060149423 - Method for Satisfying Variable Power Demand". Further, the full Disclosure, especially the Claims section, is quite detailed and lengthy, and, for the sake of clarity, we'll forego reproduction of the details. In brief, the product synthesis gas, made, as detailed, from Coal, perhaps in combination with carbonaceous wastes, with sewer treatment sludge again specified, can, if generated in a vessel that contains the pressure created during the gasification process, be passed directly into a turbine for the generation of electricity; or, the hot syngas can be used to heat a "heat transfer fluid" in a separate, closed circuit, which "fluid" can actually be a segregated portion of the product syngas, and, that "transfer fluid" can then be directed to a turbine for generating electricity. In either case, no syngas is actually combusted.).

Summary: At a great economic benefit, a portion of the synthesis gas may be used as said heat transfer fluid. Some of said synthesis gas may be introduced into the aforesaid loop of heat transfer fluid as make-up and to replace leakage from for example seals and flanges.

The remainder of the synthesis gas may be reacted over a catalyst to produce chemicals. For example, a stream of of synthesis gas having a mole ratio (H2 /CO) in the range of about 2 to 12 and at a temperature in the range of about 400 to 750 F may be passed through a chamber containing methanol catalyst to synthesize methanol".

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The above "methanol" is, of course, only one of the valuable products we can synthesize from blends of Carbon Monoxide and Hydrogen generated from Coal; and, that is in addition to the "electrical energy" which is co-produced through interaction of the hot synthesis gas with, via a "heat transfer fluid", "an expansion turbine".

In passing, we'll remind you, that, as explained for one example in:

ExxonMobil "Coal to Clean Gasoline" | Research & Development | News; concerning: "'Coal to Clean Gasoline'; ExxonMobil Research and Engineering Company, USA; ExxonMobil's methanol to gasoline technology for the production of clean gasoline from coal";

once we have Methanol, as produced herein, along with electrical power, in a process that starts with Coal gasification, we can then convert that Methanol rather directly into Gasoline.

In any case, Texaco reaffirmed the potentials disclosed in "United States Patent 4,009,383 - Partial Oxidation Process", and also identified some other intriguing potentials for utilizing the heat energy contained in synthesis gas produced via Coal gasification in the subsequent:

"United States Patent: 4184322 - Partial Oxidation Process 4,184,322

Partial oxidation process - Texaco Inc.

Date: January 22, 1980

Inventors: Peter Paull, CT, and Rodney McGann, CA

Assignee: Texaco, Inc., NY

Abstract: Sensible heat in the hot effluent gas stream leaving a partial oxidation gas generator for the production of gaseous mixtures comprising H2 +CO i.e. synthesis gas, reducing gas, or fuel gas, is used at maximum temperature to heat a stream of gaseous heat transfer fluid comprising a portion of the product gas circulating in the substantially closed loop. The heat transfer fluid serves as the working fluid in a turbine that produces mechanical work, electrical energy, or both. Further, the heat transfer fluid leaving the turbine may be used to preheat hydrocarbonaceous feed and free-oxygen containing gas which is then introduced into the gas generator. Optionally, by-product superheated steam may be produced at high temperature levels for use in the gas generator and as the working fluid in an expansion turbine. The high steam superheat temperatures result in higher conversion efficiencies. A shell and tube heat exchanger in which cleaned and optionally purified generator gas is continuously bled from inside the tubes to the outside, or the reverse is employed. By this means a continuously flowing protective sheath or curtain of the comparatively cooler bleedstream is placed between the surfaces of the tubes and headers, if any, in the heat exchanger and the surrounding hot effluent gas stream from the gas generator which enters the heat exchanger at maximum temperature. The surfaces of the tubes and headers, if any, are thereby protected against corrosive gas attack and deposits of ash, slag, and soot. The bleedstream mixes with the effluent gas stream passing through the heat exchanger and a portion of this mixture is recycled as make-up.

Background and Field: This invention pertains to a partial oxidation process for making synthesis gas, fuel gas, or reducing gas along with mechanical work, electrical energy, or both. ... In the partial oxidation process, the effluent gas stream leaving the gas generator at a temperature in the range of about 1500  to 3000 F must be cooled below the equilibrium temperature for the desired gas composition. This is presently done by quenching the effluent gas stream in water, or by cooling the gas stream in a waste heat boiler, thereby producing saturated steam. Both of these methods of gas cooling result in large increases in entropy and reduced thermal efficiencies. This problem is substantially overcome in the subject process by using the sensible heat in the hot effluent gas stream leaving the partial oxidation gas generator at a higher level of heat exchange.

In another embodiment of the process, the effluent gas stream directly after being passed in heat exchange with said gaseous heat transfer fluid in said first heat exchange zone is passed directly into a second heat exchange zone in indirect noncontact heat exchange with a continuous stream of steam. The steam was previously produced downstream in a third heat exchange zone. Thus, superheated steam may be produced in the second heat exchange zone at a temperature in the range of about 750 F to 1100 F and a pressure in the range of about 65 to 3800 psia. 

At least a portion of the by-product superheated steam produced by the subject process may be introduced into the partial oxidation gas generator where it may react and thereby contribute to the amount of hydrogen in the effluent gas stream.

Further, the thermal efficiency of the process is improved. Condensation problems that may result when steam and hydrocarbonaceous fuels are mixed together may be avoided by using superheated steam.

Advantageously, a portion of the superheated steam may be used as the working fluid in a turbocompressor to compress air which is fed to an air separation unit for producing substantially pure oxygen ... . At least a portion of this oxygen may be introduced into the gas generator as the oxidant reactant.

The superheated steam may also be used as the working fluid in a turboelectric generator. Starting with superheated steam at a very high temperature level and converting the heat into electricity favorably affects the conversion effliciency".

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So, not only can the by-product heat of Coal gasification be used to generate co-product electricity, heat that is generated along with the synthesis gas that can be used to make liquid and gaseous hydrocarbon fuels, but, it can be used as well, through various intermediate processes, to generate supplemental Hydrogen, for addition to the synthesis gas to improve the Carbon Monoxide-to-Hydrogen ratios for hydrocarbon synthesis; and, elemental Oxygen, to improve the partial oxidation/gasification process and reduce the formation of Nitrogen oxide contaminants.

Should you take the time to examine the full Disclosure of "United States Patent 4,184,322 - Partial Oxidation Process", you will also see that the byproduct gasification heat, in addition to enabling provision of "superheated steam" to the gasification process for improving hydrogen production, etc., can also be used to preheat the Coal and other "hydrocarbonaceous feed" - - which, again, can include stuff like sewage treatment plant sludge and waste tires - - and thus further improve the efficiency of the gasification process.

Even further, a closer examination of "United States Patent 4,184,322" will reveal that Texaco, as in the above-cited Eastman Chemical process of "US Patent Application 20060149423 - Method for Satisfying Variable Power Demand", also allows for the actual combustion of some of the synthesis gas, to provide even more heat energy for the generation of even more electrical power, should circumstances warrant.

In any case, we have herein even more exposition of some pretty sophisticated, and seemingly very efficient, Coal-to-Hydrocarbon conversion technology; Coal conversion technology that enables the production of both badly-needed liquid fuels and chemicals, like "methanol", and industrially-vital electric power, in a single, integrated facility that relies on, as it's basic raw material, the United States of America's one truly abundant fossil resource:

Coal.


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