Method for forming a plurality of plugs of carbonaceous material
A feedstock delivery system transfers a carbonaceous material, such as municipal solid waste, into a product gas generation system. The feedstock delivery system includes a splitter for splitting bulk carbonaceous material into a plurality of carbonaceous material streams. Each stream is processed using a weighing system for gauging the quantity of carbonaceous material, a densification system for forming plugs of carbonaceous material, a de-densification system for breaking up the plugs of carbonaceous material, and a gas and carbonaceous material mixing system for forming a carbonaceous material and gas mixture. A pressure of the mixing gas is reduced prior to mixing with the carbonaceous material, and the carbonaceous material to gas weight ratio is monitored. A transport assembly conveys the carbonaceous material and gas mixture to a first reactor where at least the carbonaceous material within the mixture is subject to thermochemical reactions to form the product gas.
1. A method for forming a new plug of densified carbonaceous material in a cylinder already having a series of previously formed plugs pressed together, and supplying a leading plug of said series of previously formed plugs to a pressurized first reactor,
the cylinder (D 30 ) comprising a first opening (D 19 ) through which carbonaceous material ( 2 D- 01 ) is introduced into the cylinder, and a first output (D 45 ) through which the leading plug is supplied to the pressurized first reactor;
the method comprising:
(a) introducing, via the first opening (D 19 ), a quantity of carbonaceous material having a density of 4 pounds per cubic foot to 50 pounds per cubic foot;
(b) while said plurality of previously formed plugs are prevented from advancing within the cylinder, compressing said carbonaceous material (D+1) against a nearest plug of said plurality of previously formed plugs, to thereby form a new plug against said plurality of previously formed plugs;
(c) advancing the new plug and said series of previously formed plugs such that the leading plug appears at the cylinder's first output (D 45 );
(d) removing the leading plug from the cylinder, thereby leaving behind a new series of previously formed plugs; and
(e) shredding the removed leading plug and introducing the shredded carbonaceous material therefrom into the pressurized first reactor, wherein:
said series of previously formed plugs are sufficiently dense to maintain a pressure difference between the cylinder's first opening and the pressurized first reactor.
2. The method according to claim 1 , wherein:
the series of previously formed plugs creates a pressure difference that ranges from 9 pounds per square inch to 75 pounds per square inch.
3. The method according to claim 1 , wherein:
the series of previously formed plugs includes at least a first plug ( 1 D) and a second plug ( 2 D) each having a length ranging from 10 inches to 15 inches.
4. The method according to claim 1 , wherein:
the series of previously formed plugs includes at least a first plug ( 1 D) and a second plug ( 2 D) each having a diameter ranging from 10 inches to 15 inches.
5. The method according to claim 1 , further comprising:
weighing the carbonaceous material before step (a).
6. The method according to claim 1 , further comprising:
creating a new plug within the cylinder (D 30 ) about every 15 seconds, by repeating steps (a) through (e).
7. The method according to claim 1 , wherein:
each plug within the series of previously formed plugs weighs from about 32 pounds to about 40 pounds.
8. The method according to claim 1 , further comprising:
mixing a gas with the shredded carbonaceous material after step (e) and prior to introducing the shredded carbonaceous material into the pressurized first reactor.
9. The method according to claim 8 , further comprising:
mixing the shredded carbonaceous material with gas at a mass ratio of carbonaceous material to gas that is less than 75 pounds of carbonaceous material per pound of gas.
10. The method according to claim 8 , where the gas is carbon dioxide or an oxygen-containing gas.
11. The method according to claim 10 , wherein the mixing gas is carbon dioxide and the method comprises:
endothermically reacting a portion of the carbonaceous material in the first reactor with a portion of the carbon dioxide.
12. The method according to claim 1 , further comprising:
(f) introducing steam into the first reactor such that a mass ratio of the steam to carbonaceous material in the range of 0.125:1 to 3:1; and
(g) operating the first reactor at a temperature between 570° C. and 900° C. to endothermically react the carbonaceous material with the steam to produce a first reactor product gas.
13. The method according to claim 12 , wherein the first reactor product gas of step (g) further comprises H2, CO, CO2, char, semi-volatile organic compounds (SVOC), and volatile organic compounds (VOC).
14. The method according to claim 13 , further comprising:
(i) providing a second reactor;
(ii) introducing at least a portion of the char into the second reactor;
(iii) reacting the char introduced into the second reactor, with an oxygen-containing gas in the second reactor to produce a second reactor product gas; and
(iv) combining the first reactor product gas with the second reactor product gas to form a combined product gas.
15. The method according to claim 14 , comprising:
operating the first reactor and the second reactor at a superficial fluidization velocity range between 0.5 ft/s to about 25.0 ft/s.
16. The method according to claim 14 , further comprising:
(v) transferring heat from the second reactor to a heat transfer medium via a second reactor heat exchanger in thermal contact with an interior of the second reactor, the heat transfer medium comprising steam; and
(vi) introducing at least a first portion of the steam that has been heated by the second reactor, into the first reactor, to react with the carbonaceous material.
17. The method according to claim 1 , further comprising:
(f) introducing carbon dioxide gas to the first reactor such that a mass ratio of the carbon dioxide gas to carbonaceous material in the range of 0.1 to 1:1; and
(g) operating the first reactor at a temperature between 600° C. and 1000° C. to endothermically react the carbonaceous material with the carbon dioxide to produce a first reactor product gas.
18. The method according to claim 1 , further comprising:
(f) introducing an oxygen-containing gas to the first reactor such that a mass ratio of the oxygen-containing gas to carbonaceous material in the range of 0.1 to 0.5:1; and
(g) operating the first reactor at a temperature between 500° C. and 1400° C. to exothermically react the carbonaceous material with the oxygen-containing gas to produce a first reactor product gas.
19. The method according to claim 1 , further comprising:
combusting a fuel source in a first reactor heat exchanger to form a combustion stream, said combustion stream indirectly heating particulate heat transfer material present in the first reactor.
20. The method according to claim 1 , wherein the first reactor operates at a superficial fluidization velocity range between 0.6 ft/s to about 1.2 ft/s.