Method, system and equipment for gasification-liquefaction disposal of municipal solid waste
A gasification-liquefaction disposal method, system and equipment for MSW are disclosed. The method involves the MSW pretreatment of dehydrating and separating, thus reducing water and inorganic substance content of the waste. Then, the MSW is introduced into a plasma gasifier ( 23 ) by a carbon dioxide air-sealed feeding device ( 13 ) and gasified therein to obtain hydrogen-rich syngas. The hydrogen-rich syngas is then cooled, deacidified, dedusted and separated to obtain carbon dioxide. Then, the hydrogen-rich syngas is catalyzed to produce methanol product in a methanol synthesis reactor ( 52 ). The separated carbon dioxide is sent back to a carbonation reaction chamber ( 2007 ) of a gasification system to perform carbonation reaction with calcium oxide, thereby releasing heat to provide assistant heat energy for gasification and avoiding greenhouse gas from being discharged into environment. Exhaust gas is returned to the plasma gasifier ( 23 ) for remelting treatment, thus forming a closed-loop circulation production system and realizing the disposal of the MSW with zero discharge and no pollution, thereby avoiding dioxin pollution and converting the MSW to chemical raw materials and fuel needed by mankind. The method, system and equipment are suitable for harmless and recycling disposal of MSW, industrial high polymer waste, composting waste and waste in waste sorting sites.
1. A method for gasification-liquefaction disposal of municipal solid waste (MSW) using calcium oxide assisting plasma gasification technology, the method comprising the steps of:
dehydrating and sorting the MSW or an organic waste in a preprocessing process to reduce water and inorganic material contents, then feeding the dehydrated and sorted MSW or organic waste into a plasma gasifier through a CO 2 gas sealed feeding device;
providing the plasma gasifier with a drying section, a pyrolysis section and a gasification section in an order of upper, middle and lower segments;
drying, pyrolyzing and in the MSW or organic waste in the plasma gasifier to produce hydrogen-rich syngas in which CO and H 2 are main components;
providing a plasma torch in the gasification section of the plasma gasifier and using water steam as a gasifying agent and working gas;
heating the water steam by the plasma torch to >4200° C., so that water molecules are decomposed completely, generating H*, H 2 *, HO*, O*, O 2 * and H 2 O* that are then directly sprayed on MSW carbon in the gasification section of the plasma gasifier, wherein MSW carbon serves as hydrogen and oxygen absorber to generate CO and H 2 ; adopting calcium oxide assisting plasma gasification, and providing a reaction chamber of a carbonator in the gasification system; the heat emitted by carbon dioxide absorbing calcium oxide to generate calcium carbonate can provide a supplementary heat source for the gasification, drying and preheating of new waste materials fed in the plasma gasifier, so as to reduce energy consumption of the plasma torch;
introducing the pyrolysis gas produced at the pyrolysis section of the plasma gasifier into the carbonator reaction chamber, and then as a carrier gas, the pyrolysis gas carrying calcium oxide, calcium carbonate mixture and heat into the drying section of the plasma gasifier; also serving as a dechlorination or desulfurizing agent, calcium oxide removing dioxin precursors, chlorides and sulfides in an environment of excessive calcium oxide; then introducing the pyrolysis gas into a gas-solid separator wherein calcium oxide and calcium carbonate are separated, and then fed into the gasification section of the plasma gasifier, so that methane, gaseous tar, ethylene, ethane, water steam, are pyrolyzed and chemically reacted to produce a 1 hydrogen-rich syngas wherein high-quality hydrogen and carbon monoxide are main components and dioxin is thoroughly decomposed at the same time;
outputting the hydrogen-rich syngas out of the plasma gasifier, and after cooling in an exhaust heat boiler, deacidifying and dedusting the hydrogen-rich syngas in a gas purifying equipment that consists of an absorption reactor, a cyclone duster and a bag dust collector;
absorbing carbon dioxide in the syngas by a potassium carbonate solution in a CO 2 absorbing tower to generate potassium bicarbonate;
feeding the syngas after removing carbon dioxide into a methanol synthesis reactor to produce methanol and feeding the potassium bicarbonate into a regeneration reactor to decompose to potassium carbonate solution and carbon dioxide by heating;
returning the decomposed potassium carbonate solution to the CO 2 absorbing tower for recycling and feeding the decomposed carbon dioxide into the carbonation reaction chamber of the gasification system for carbonation reaction with calcium oxide;
catalyzing the hydrogen-rich syngas to form methanol product in the methanol synthesis reactor;
mixing the methanol product with limewater in a mixing absorber of an end purifying device to allow residual contaminants and carbon dioxide to be absorbed by the limewater; then separating the methanol out through a distillation column, and returning unreacted gas to the methanol synthesis reactor for circulating reaction; after decontamination, feeding limewater back to the mixing absorber for recycling; and
returning exhaust to the plasma gasifier for recycling, and forming a closed loop production system.
2. The method for gasification-liquefaction disposal of MSW according to claim 1 , wherein operating temperature of the drying section is controlled at between 120 to 300° C.; operating temperature of the pyrolysis section is controlled between 300 to 1000° C.; operating temperature of the gasification section is controlled at between 1000 to 1300° C.; operating pressure in the plasma gasifier is controlled at between −30 Pa˜+5 kPa; when clinker is melted to a liquid slag and discharged, a liquid slag zone is provided between the gasification section and a slag port, and a plasma torch is provided in the slag zone; operating temperature of the slag zone is controlled at between 1300˜1600° C.
3. A MSW gasification-liquefaction disposal system using a plasma gasification equipment, the system comprising a preprocessing device, a CO 2 gas sealed feeding device, a plasma gasifier, a plasma torch, a gas-solid separator, a circulating fan, a first heat exchanger, a carbonation reaction chamber, a waste heat boiler, an absorption reactor, a cyclone duster, a bag dust collector, a CO 2 absorber, a regeneration tower, a methanol synthesis reactor, a mixing absorber, a distillation column, a decontaminator, a circulating pump, a methanol tank and connecting ducts; wherein: the preprocessing device comprises a waste storage pit and a sorting machine; an inner space of plasma gasifier is provided with a drying section, a pyrolysis section and a gasification section; a waste material inlet, a heat carried gas inlet and a pyrolysis gas outlet are provided in the drying section; an output interface of heat carried gas is provided in the pyrolysis section; an input interface of pyrolysis gas is provided in the gasification section; an output interface of syngas is provided in a joint position of the pyrolysis section and the gasification section; the plasma torch is provided in the gasification section in a lower part of the plasma gasifier; a first heat exchanger consists of a atmolysis chamber, a heat exchange chamber and a gas collection chamber; an input interface of pyrolysis gas is provided in the atmolysis chamber; an output interface of heat carried gas is provided in the heat change chamber; an output interface of pyrolysis gas is provided in the gas collection chamber; the carbonation reaction chamber communicates directly with the heat exchange chamber in the first heat exchanger; the carbonation reaction chamber is provided with an input interface of heat carried gas, an inputting apparatus of the calcium oxide and an input interface of carbon dioxide; the CO 2 absorber is provided with an input interface of the syngas, an output interface of syngas, a KHCO 3 output interface and an input interface of the K 2 CO 3 solution; the regeneration tower is provided with an input interface of KHCO 3 , an output interface of CO 2 and an output interface of the K 2 CO 3 solution;
the waste storage pit is constantly connected with the sorting machine through a crane grab; the sorting machine is constantly connected with a feed inlet of the CO 2 gas sealed feeding device of the plasma gasifier by a belt conveyor or screw feeders; an outlet of CO 2 gas sealed feeding device is connected to a waste inlet of the plasma gasifier; an output interface of heat carried gas of the plasma gasifier is connected to an input interface of heat carried gas of the carbonation reaction chamber; an output interface of heat carried gas of the first heat exchanger is connected to an inlet heat carried gas of the plasma gasifier; the outlet of heat carried gas of the plasma gasifier is connected to a mixture inlet of the gas-solid separator; a gaseous substance outlet of the gas-solid separator is connected to an input interface of pyrolysis gas of the first heat exchanger through a circulating fan; an output interface of pyrolysis gas of the first heat exchanger is connected to an input interface of pyrolysis gas of the plasma gasifier; an output interface of syngas of the plasma gasifier is connected to an input interface of syngas of the waste heat boiler; an output interface of syngas of the waste heat boiler is connected to an input interface of syngas of the absorption reactor; an output interface of syngas of the absorption reactor is connected to a mixture input interface of syngas of the cyclone duster; a solid substance outlet of the cyclone duster is connected to the connecting pipe of a syngas input interface of the absorption reactor; the solid gaseous substance outlet of the cyclone duster is connected to a syngas input interface of the bag dust collector; an output interface of syngas of the bag dust collector is connected to a syngas input interface of the CO 2 absorbing tower; an output interface of KHCO 3 of the CO 2 absorbing tower is connected to the input interface of KHCO 3 of the regeneration tower; the CO 2 output interface of the regeneration tower is connected to an input interface of CO 2 of the carbonation reaction chamber; the output interface of K 2 CO 3 solution of the regenerating tower is connected to the input interface of K 2 CO 3 solution of the CO 2 absorbing tower; the output interface of syngas of CO 2 absorbing tower is connected to an induction port of a first compressor; an exhaust port of the first compressor is connected to a virgin gas port of a methanol synthesis reactor; a methanol gas outlet of the methanol synthesis reactor is connected to a methanol gas inlet of the mixing absorber; a mixture outlet of mixing absorber is connected to a mixture input interface of the distillation column; an unreacted gas outlet of the distillation column is connected to a return-air interface of the methanol synthesis reactor via an unreacted gas pipeline and a second compressor; a methanol product outlet of the distillation column is connected to the methanol tank; a limewater outlet of the distillation column is connected to an input interface of the decontaminator; the limewater outlet of the decontaminator is connected to a water inlet of the circulating pump; a water outlet of the circulation pump is connected to a limewater inlet of the mixing absorber.
4. The system for gasification-liquefaction disposal of MSW according to claim 3 , wherein the preprocessing device further comprises a spiral moisture expelling and feeding device and a digester; the spiral moisture expelling and feeding device is provided between the sorting machine and the CO 2 gas sealed feeding device; a waste material outlet of the sorting machine is constantly connected to a hopper of the spiral moisture expelling and feeding device through a belt conveyor; the material outlet of the spiral moisture expelling and feeding device is connected to a material inlet of CO 2 gas sealed feeding device through a first duct; the outlet of CO 2 gas sealed feeding device is connected to a material inlet of the plasma gasifier through a second duct; leachate interfaces of the waste storage pit, the sorting machine and the spiral moisture expelling and feeding device are connected to a material outlet of the digester; a biogas outlet of the digester is connected to the gasification section of the plasma gasifier.
5. The system for gasification-liquefaction disposal of MSW according to claim 3 , wherein an induced-draft fan and a carbon monoxide conversion reactor are also provided between the bag dust collector and the CO 2 absorber; the output interface of syngas of bag dust collector is connected to a suction inlet of the induced-draft fan; an air outlet of the induced-draft fan is connected to a syngas input interface of the CO shift reactor; an output interface of syngas of the CO shift reactor is connected to the syngas input interface of CO 2 absorbing tower;
a third compressor and a syngas storage tank are also provided between the CO 2 absorbing tower and the first compressor; an output interface of syngas of the CO 2 absorbing tower is connected to an induction port of the third compressor; an exhaust port of the third compressor is connected to an input interface of the syngas storage tank; an output interface of the syngas storage tank is connected to a suction port of the first compressor;
an exhaust gas interface and a ammonia synthesizing equipment are provided in an unreacted gas pipeline at a terminal end of a methanol synthesis reactor, and meanwhile an exhaust feedback pipeline is provided between the plasma gasifier and a terminal end purification equipment; an exhaust gas interface of the unreacted gas pipeline is, via a control valve, respectively connected to the exhaust feedback pipeline of the plasma gasifier and a material inlet interface of the ammonia synthesizing equipment; an exhaust gas outlet of the ammonia synthesizing equipment is connected to the exhaust feedback pipeline of the plasma gasifier.
6. A MSW gasification-liquefaction disposal system using a plasma gasification equipment, the system comprising a preprocessing device, a CO 2 gas sealed feeding device, a plasma gasifier, a plasma torch, a circulating fan, a first heat exchanger, a waste heat boiler, an absorption reactor, a cyclone duster, a bag dust collector, a hydrogenation absorber, a methanol synthesis reactor, a mixing absorber, a distillation column, a decontaminator, a circulating pump, a methanol tank and connecting ducts; wherein: a preprocessing device comprises a waste storage pit and a sorting machine; an inner space of the plasma gasifier is provided with a drying section, a pyrolysis section and a gasification section; a waste material inlet and a pyrolysis gas outlet are provided in the drying section; an input interface of pyrolysis gas is provided in the gasification section; a syngas output interface is provided in a joint position of the pyrolysis section and the gasification section; the plasma torch is provided in gasification section in the lower part of the plasma gasifier; the second heat exchanger consists of an atmolysis chamber, a heat exchange chamber and a gas collection chamber; the input interface of pyrolysis gas is provided in the atmolysis chamber; the syngas input interface and output interface are provided in heat exchange chamber; an output interface of pyrolysis gas is provided in the gas collection chamber;
the waste storage pit is constantly connected with the sorting machine through a crane grab; the sorting machine is constantly connected with a feed inlet of the CO 2 gas sealed feeding device of the plasma gasification equipment by a belt conveyor or screw feeders; an outlet of CO 2 gas sealed feeding device is connected to an inlet of the plasma gasifier; a pyrolysis gas outlet of the plasma gasifier is connected to an input interface of pyrolysis gas of the second heat exchanger through the circulating fan; an output interface of pyrolysis gas of the second heat exchanger is connected to an input interface of pyrolysis gas in the gasification section of the plasma gasifier; an output interface of syngas of the plasma gasifier is connected to an input interface of syngas of the second heat exchanger; an output interface of syngas of the second heat exchanger is connected to an input interface of syngas of the waste heat boiler; an output interface of syngas of the waste heat boiler is connected to an input interface of syngas of the absorption reactor; an output interface of syngas of the absorption reactor is connected to a mixture input interface of syngas of the cyclone duster; a solid substance outlet of the cyclone duster is connected to a connecting pipe of the syngas input interface of the absorption reactor; a gaseous substance outlet of the cyclone duster is connected to a syngas input interface of the bag dust collector; an output interface of syngas of the bag dust collector is connected to an induction port of a first compressor; an exhaust port of the first compressor is connected to an input interface of a syngas storage tank; an output interface of the syngas storage tank is connected to an input interface of the hydrogenation mixer; an output interface of syngas of the hydrogenation mixer is connected to a suction inlet of a second compressor; an exhaust port of the second compressor is connected to a virgin gas port of the methanol synthesis reactor; a methanol gas outlet of the methanol synthesis reactor is connected to a methanol gas inlet of the mixing absorber; a mixture outlet of the mixing absorber is connected to a mixture input interface of a distillation column; an unreacted gas outlet of the distillation column is connected to a return-air interface of the methanol synthesis reactor via an unreacted gas pipeline and a third compressor; a methanol product outlet of the distillation column is connected to the methanol tank; a limewater outlet of the distillation column is connected to an input interface of the decontaminator; a limewater outlet of the decontaminator is connected to a water inlet of the circulating pump; a water outlet of the circulation pump is connected to a limewater inlet of the mixing absorber.
7. The system for gasification-liquefaction disposal of MSW according to claim 6 , wherein the preprocessing device further comprises a spiral moisture expelling and feeding device and a digester; the spiral moisture expelling and feeding device is provided between the sorting machine and the CO 2 gas sealed feeding device; a waste material outlet of the sorting machine is constantly connected to a hopper of the spiral moisture expelling and feeding device through a belt conveyor; the material outlet of spiral moisture expelling and feeding device is connected to a material inlet of CO 2 gas sealed feeding device through a first duct; an outlet of CO 2 gas sealed feeding device is connected to the material inlet of the plasma gasifier through a second duct; leachate interfaces of the waste storage pit, the sorting machine and the spiral moisture expelling and feeding device are connected to a material outlet of the digester; a biogas outlet of the digester is connected to the gasification member of the plasma gasification furnace;
an induced-draft fan is also provided between the waste heat boiler and the absorption reactor; a syngas outlet of the waste heat boiler is connected to an air inlet of the induced-draft fan; an air outlet of the induced-draft fan is connected to the syngas input interface of the absorption reactor;
an exhaust gas interface and an ammonia synthesizing equipment are provided in an unreacted gas pipeline at a terminal end of a methanol synthesis reactor; meanwhile an exhaust feedback pipeline is provided between the plasma gasifier and the terminal end of the methanol synthesis reactor; an exhaust gas interface of the unreacted gas pipeline is, via a control valve, respectively connected to the exhaust feedback pipeline of the plasma gasifier and a material inlet interface of ammonia synthesizing equipment; the exhaust gas outlet of the ammonia synthesizing equipment is connected to the exhaust feedback pipeline of the plasma gasifier.
8. An equipment of gasification-liquefaction disposal for MSW, the equipment comprising a gasification device comprising a plasma gasifier, a plasma torch, a circulating fan, a first heat exchanger and connecting ducts; wherein: the plasma gasifier is divided into a drying section, a pyrolysis section and a gasification zone from top to bottom; the drying section, the pyrolysis section and the gasification zone communicate directly; the plasma torch is provided in a furnace wall of the gasification section; a waste material inlet and a pyrolysis gas outlet are provided in an upper part of the drying section; a first input interface of the pyrolysis gas is provided in the gasification section; a slag hole is provided in a lower part of the gasification section; a first output interface of syngas is provided in a joint position of the pyrolysis section and the gasification section; the first heat exchanger consists of an atmolysis chamber, a heat exchange chamber, a heat exchange bundle and a gas collection chamber; the atmolysis chamber, the heat exchange chamber and the gas collection chamber are arranged into upper, middle and lower parts, respectively; the heat exchange chamber is in the middle; the atmolysis chamber, the heat exchange chamber and the gas collection chamber are inside a steel shell; an exterior of the steel shell is covered with an insulation material; the atmolysis chamber and the heat exchange chamber are separated by an upper baffle; the heat exchange chamber and the gas collection chamber are separated by a lower baffle; the heat exchange bundle is provided in the heat exchange chamber, with both ends intersecting the atmolysis chamber and the gas collection chamber; the atmolysis chamber, the bundle and the gas collection chamber constitute a return passage of pyrolysis gas; a second input interface of pyrolysis gas is provided in the atmolysis chamber; the heat change chamber is provided with an input interface of syngas and a second output interface of syngas; an output interface of pyrolysis gas is provided in the gas collection chamber;
a pyrolysis gas outlet in the drying section of the plasma gasifier is connected to an air inlet of the circulating fan; an air outlet of the circulating fan is connected to the second input interface of pyrolysis gas in the atmolysis chamber of the first heat exchanger; the output interface of pyrolysis gas in the gas collection chamber of the first heat exchanger is connected to the first input interface of the pyrolysis gas in the gasification section of the plasma gasifier; the first output interface of syngas in the plasma gasifier is connected to an input interface of syngas in the heat exchange chamber of the first heat exchanger.
9. The equipment for gasification-liquefaction disposal of MSW according to claim 8 , wherein a calcium oxide torch is provided in a furnace wall of the plasma gasifier; the calcium oxide torch is provided with a CO 2 input interface and a calcium oxide input interface; a gas-solid separator is provided between a pyrolysis gas outlets in a drying section of the plasma gasifier and an air inlet of the circulating fan; the pyrolysis gas outlet in the drying section of the plasma gasifier is connected to a mixture inlet of the gas-solid separator; a gaseous material outlet of the gas-solid separator is connected to the air inlet of the circulating fan; the solid material outlet of the gas-solid separator is connected to the input interface of the calcium oxide of the calcium oxide torch; the CO 2 input interface of the calcium oxide torch is connected to the CO 2 gas pipeline.
10. The equipment for gasification-liquefaction disposal of MSW according to claim 8 , wherein the gasification section of the plasma gasifier is also provided with a fly ash returning interface, a biogas input interface and an exhaust gas input interface; a heat exchange chamber of the first heat exchanger is also provided with a soot-blowing opening and a soot door; the soot door of a first heat exchanger is connected to the fly ash returning interface in the plasma gasifier; the soot-blowing opening of the first heat exchanger is connected to a soot-blowing fan; the air inlet of the soot-blowing fan is connected to the syngas pipeline; the air outlet of the soot-blowing fan is connected to the soot-blowing opening of the first heat exchanger.