Plasma induced hydrogen production

A plasma pyrolysis process for the production and recovery of high purity hydrogen from an input feed comprising an aliphatic hydrocarbon, the process comprising:

• a. heating the input feed to a temperature of at least 850° C. using an interchanger to provide a heated feed;
• b. passing the heated feed to a plasma reactor comprising two carbon electrodes separated by a gap that each receive electric power from an electric power source to create a plasma environment having a temperature in a range 1400 to 1550° C. to pyrolyze aliphatic hydrocarbon and produce an output stream comprising hydrogen, carbon, and aliphatic hydrocarbon;
• c. injecting a first product stream and/or a second product stream in the gap between the two electrodes to stabilize the plasma environment;
• d. passing the output stream to the interchanger, transferring heat from the output stream to at least partially heat the input feed according to step a, and cooling the output stream to produce a cooled stream with a temperature in a range of 600 to 1150° C.;
• e. passing the cooled stream to a secondary heat recovery zone to recover heat from the cooled stream and produce a cool stream;
• f. passing the cool gas stream to a particle separator to remove particles comprising carbon from the cool stream to produce a gas phase, cleaned gas stream comprising hydrogen and a particle output stream comprising carbon wherein the particle separator comprises a cyclone that separates particles from gases in the cool stream to produce a first particle stream comprising carbon particles and a reduced particle stream having a particle loading less than that of the cool stream, the reduced particle stream passes to a bag filter unit that passes the reduced particle stream through bag filter elements to produce a second particle stream comprising carbon particles and to produce the cleaned gas stream;
• the cleaned gas stream exits the particle separator at a pressure in a range greater than 0 barg to 3 barg, a gas phase cleaning stream passes through the bag filter elements in reverse flow to remove particles from the bag filter elements, and the gas phase cleaning stream comprises a gas that will not combust with any components of the reduced particle stream;
• g. compressing the cleaned gas stream to a pressure in a range 8 to 12 barg and passing the compressed, cleaned gas stream to a first pressure swing adsorption unit and recovering from the first pressure swing adsorption unit a first permeate that provides the first product stream consisting essentially of hydrogen at a concentration of at least 99.99% and a first retentate stream containing hydrogen;
• and,
• h. compressing the first retentate stream and passing the first retentate to a second pressure swing adsorption unit and recovering from the second pressure swing adsorption unit a second retentate and a second permeate that provides the second product stream consisting essentially of hydrogen at a concentration 99.99 wt. % hydrogen.

A plasma pyrolysis process for the production and recovery of high purity hydrogen from an input feed comprising methane, the process comprising:

• a. heating the input feed to a feed temperature of at least 850° C. in a shell and tube interchanger to provide a heated feed wherein the tubes comprise silicon carbide, the input feed passes through the shell side of the interchanger, and the interchanger supplies enough heat to maintain the input feed at the feed temperature;
• b. passing the heated feed to a plasma reactor comprising two carbon electrodes separated by a gap that each receive electric power from a DC source to create a plasma environment having a temperature in a range of 1400 to 1550° C. to pyrolyze methane and produce an output stream comprising hydrogen, carbon, and methane;
• c. injecting a portion of a first product stream and/or a second product stream in the gap between the two electrodes to stabilize the plasma environment;
• d. passing the output stream to the interchanger, transferring heat from the output stream to heat the input feed to the feed temperature according to step a., and cooling the output stream to produce a cooled stream with a temperature in a range of 600 to 1150° C.;
• e. passing the cooled stream to a secondary heat recovery zone to recover heat from the cooled stream and produce a cool stream having a temperature of 200 to 300° C.
• f. passing the cool gas stream to a particle separator to remove particles comprising carbon from the cool stream to produce a gas phase, cleaned gas stream comprising hydrogen along with unconverted hydrocarbons and a particle output stream comprising carbon particles wherein the particle separator comprises a cyclone with an involute inlet that separates particles from gases in the cool stream to produce a first particle stream comprising carbon particles and a reduced particle stream having a particle loading less than that of the cool stream, the reduced particle stream enters a bag filter unit that passes the reduced particle stream through bag filter elements to produce a second particle stream comprising carbon particles and to produce the cleaned gas stream;
• the cleaned gas stream exits the particle separator at a pressure in a range of 0.1 to 0.5 barg, a gas phase cleaning stream passes through the bag filter elements in reverse flow to remove particles from the bag filter elements, and the gas phase cleaning stream comprises hydrogen;
• g. compressing the cleaned gas stream to a pressure in a range of 8 to 12 barg in a water lubricated screw compressor that receives essentially no oil and passing the compressed, cleaned gas stream to a first pressure swing adsorption unit and recovering from the first pressure swing adsorption unit a first permeate that provides the first product stream consisting essentially of hydrogen at a concentration of at least 99.99% and a first retentate containing hydrogen;
• and,
• h. compressing the first retentate stream to a pressure in a range of 8 to 12 barg with a water lubricated screw compressor that receives essentially no oil and passing the first retentate to a second pressure swing adsorption unit and recovering from the second pressure swing adsorption unit a second retentate and a second permeate that provides the second product stream consisting essentially of hydrogen at a concentration 99.99 wt % hydrogen.