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 using an internal combustion engine as a reactor under fuel-rich conditions, comprising:
starting the engine using a feed gas having an initial fuel-air equivalence ratio wherein the feed gas comprises natural gas;
increasing the fuel-air equivalence ratio incrementally to generate a fuel-rich feed gas; and
while increasing the fuel-air equivalence ratio, adjusting one or more of a throttle, an ignition timing, a load coupled to the engine, a fuel pressure, power to a supercharger acting on the feed gas or part of the feed gas, and power to a preheater acting on the feed gas to maintain a fuel-air equivalence ratio to about 1.6 to 2.4.
2. The method of claim 1 , wherein the feed gas comprises hydrocarbon compounds and an oxygen containing stream.
3. The method of claim 1 , further comprising setting initial conditions prior to starting the engine as at least one of predetermined fuel pressure, partially open throttle, a first predetermined ignition timing value, and a load coupled to the engine.
4. The method of claim 3 , wherein setting the partially open throttle comprises setting the throttle at a predetermined setting below 50%.
5. The method of claim 3 , wherein setting the first predetermined ignition timing value comprises setting the ignition timing from about 5 to about 12 degrees before top dead center (BTDC).
6. The method of claim 1 , wherein starting the engine comprises setting the fuel pressure to about 0 in. H2O gauge and allowing the engine to start.
7. The method of claim 1 , wherein an engine speed between about 1000 to 2000 rotations per minute (RPM) and a temperature of an exhaust gas less than about 900° C. is maintained.
8. The method of claim 1 , wherein adjusting the ignition timing comprises advancing the ignition timing to a second predetermined value while increasing the engine load to maintain the engine speed between about 1000 to 2000 RPM.
9. The method of claim 8 , wherein the ignition timing second predetermined value is between about 8 degrees BTDC and about 28 degrees BTDC.
10. The method of claim 1 , wherein adjusting the power to the supercharger comprises initially powering the supercharger.
11. The method of claim 10 , further comprising increasing the power to the supercharger while increasing the fuel pressure to maintain the engine speed between about 1000 to 2000 RPM.
12. The method of claim 1 , wherein adjusting the throttle comprises increasing the throttle while increasing the fuel pressure and the engine load to maintain the engine speed between about 1000 to 2000 RPM.
13. The method of claim 1 , further comprising monitoring the exhaust gas temperature and modifying one or more of the fuel pressure, the throttle, and the engine load to maintain the exhaust gas temperature less than about 900° C.
14. The method of claim 1 , wherein adjusting the power to the preheater comprises initially powering the preheater.
15. The method of claim 14 , further comprising setting the preheater to an initial temperature, and raising the fuel pressure as the preheater temperature increases while maintaining the engine speed between about 1000 to 2000 RPM.
16. The method of claim 15 , wherein the preheater initial temperature is about 200° C.
17. The method of claim 8 , further comprising adjusting the ignition timing to a third predetermined value.
18. The method of claim 17 , wherein the ignition timing third predetermined value is from about 20 to about 30 degrees BTDC.
19. The method of claim 11 , further comprising increasing the power to the supercharger while adjusting the fuel pressure and the engine load to maintain the engine speed between about 1000 to 2000 RPM until a desired engine volumetric throughput is reached.
20. The method of claim 15 , further comprising when the preheater reaches the initial temperature, increasing the preheater temperature while adjusting the fuel pressure to maintain the engine speed between about 1000 to 2000 RPM until the fuel-air equivalence reaches about 1.6 to 2.4.
21. The method of claim 1 , wherein the fuel gas initial fuel-air equivalence ratio is about 1.
22. A gas reformer system, comprising:
an internal combustion engine comprising a fuel gas inlet, an exhaust gas outlet, a plurality of cylinders, an ignition timing system, a throttle, a fuel gas preheater, and a supercharger;
wherein the internal combustion engine is configured for operating with (i) a natural gas fuel gas and (ii) a fuel-air equivalence ratio of between about 1.6 and 2.4.
23. The gas reformer system of claim 22 , wherein the internal combustion engine is configured for individually adjusting a fuel gas fuel-air equivalence ratio, a fuel gas inlet temperature, an inlet manifold pressure, an ignition timing, an engine speed, an exhaust manifold pressure, and an exhaust gas temperature in order to operate with a fuel gas fuel-air equivalence ratio of between about 1.6 and 2.4.
24. The gas reformer system of claim 22 , wherein the internal combustion engine is configured to produce an exhaust gas comprising hydrogen (H2) and carbon monoxide (CO).
25. The method of claim 1 , wherein the engine comprises a plurality of cylinders and all of the cylinders operate as the reactor.
26. The gas reformer system of claim 22 , wherein the internal combustion engine is configured so all of the plurality of cylinders are configured to operate with the fuel gas with a fuel air equivalence ratio of between about 1.6 and 2.4.