Internal combustion engine as a chemical reactor to produce synthesis gas from hydrocarbon feeds
An internal combustion engine is operated at fuel-rich conditions by adjusting one or more operating parameters such as, for example, a throttle, an ignition timing, a load coupled to the engine, a fuel pressure, power to a supercharger, and power to a preheater to maintain a specified engine speed and a temperature of an exhaust gas. Operating the engine under these conditions allows the engine to function as a reformer producing a synthesis gas comprising hydrogen and carbon monoxide.
1. A method for operating an internal combustion engine under fuel-rich conditions to produce an exhaust gas comprising hydrogen and carbon monoxide, comprising:
maintaining a maintenance operating set of conditions after startup of the engine for a fuel gas, an exhaust backpressure, an intake manifold pressure, an engine speed, an ignition timing, a fuel gas fuel-air equivalence ratio, and a fuel gas inlet temperature;
increasing the fuel gas inlet temperature while maintaining the fuel gas fuel-air equivalence ratio, and monitoring methane and oxygen content of an engine exhaust gas; and
adjusting two or more of a throttle, an ignition timing, a load coupled to the engine, a fuel pressure, power to a supercharger acting on the fuel gas or part of the fuel gas, and power to a preheater acting on the fuel gas to maintain a fuel-air equivalence ratio of 1.6 to 2.4 so as to produce the exhaust gas comprising hydrogen and carbon monoxide wherein the fuel gas is a natural gas and the fuel gas is converted to the exhaust gas with a fractional conversion of between 0.9 and 1.0.
2. The method of claim 1 , wherein the initial operating exhaust backpressure is between ambient to 5 bar absolute.
3. The method of claim 1 , wherein the initial operating engine speed is between about 1000 to 2000 rotations per minute (RPM).
4. The method of claim 1 , wherein the initial operating ignition timing is between about 25 to 35 degrees before top dead center (BTDC).
5. The method of claim 1 , wherein the initial operating fuel gas inlet temperature is between about 200° C. and 270° C.
6. The method of claim 1 , wherein adjusting the ignition timing in response to the monitored methane and oxygen content comprises advancing the ignition timing if the monitored methane or oxygen content increases beyond acceptable levels.
7. The method of claim 1 , further comprising monitoring an exhaust gas temperature from each cylinder of the engine.
8. The method of claim 1 , wherein the exhaust gas comprises a combination of at least two of hydrogen (H 2 ), carbon monoxide (CO), nitrogen (N 2 ), water vapor (H 2 O), carbon dioxide (CO 2 ), and trace components.
9. The method of claim 1 , wherein the internal combustion engine is configured to produce a syngas.