Patent Publication Number: US-2013247465-A1

Title: Hydrocarbon feedstock gasifier

Description:
FIELD 
     The present invention relates to a hydrocarbon feedstock gasifier that gasifies, for example, coal as a hydrocarbon feedstock. 
     BACKGROUND 
     There is a known integrated coal gasification combined cycle (IGCC) that converts coal which is a solid hydrocarbon feedstock to coal gasification gas by a coal gasifier, and uses the coal gasification gas for a gas turbine combined cycle. 
     The integrated coal gasification combined cycle has advantages in that abundant reserves of coal resources are used, in that a thermal efficiency is high when compared to a conventional pulverized coal thermal power generation, and the discharge amount of air pollutants such as carbon dioxide is less, and in that coal ash is discharged as a glassy melted slag, and is reduced in volume. Hence, the integrated coal gasification combined cycle is being developed as a main technology of a future coal thermal power generation. 
     A two-stage two-chamber entrained flow gasifier proposed as a coal gasifier includes a combustor operated at a high temperature by char (obtained by separating, collecting, and recycling ash+non-reaction carbon in coal gasification gas) and a gasifying agent and coal injected into a first stage (lower stage) within a gasifier, and a reductor that gasifies coal injected into a second stage (upper stage) by energy of high-temperature gas from the combustor (Patent Literatures 1 and 2). 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Laid-open Patent Publication No. 2001-26787 
         Patent Literature 2: Japanese Laid-open Patent Publication No. 2009-179790 
       
    
     SUMMARY 
     Technical Problem 
     Incidentally, a reaction in a coal gasifier appropriately sets an operating condition of the gasifier based on the amount of coal injected into the gasifier, and the amount and ratio of a gasifying agent (air, oxygen, steam, CO 2 , and the like). 
     As a result, when a gasifier operating condition is set in a target gasifier, a temperature of a gasifier reductor is determined under the same condition, and an exhaust temperature of the gasifier may not be controlled. 
     Recently, as an application of coal gasification gas, there is a desire for development of a chemical gasifier that obtains a chemical feedstock such as liquid fuel including methanol (CH 3 OH), gaseous fuel including methane (CH 4 ), and the like. Hence, there is a desire for a gasifier capable of controlling a composition in produced gas (H 2 /CO ratio) at a desired value. 
     In view of the above issue, an object of the invention is to provide a hydrocarbon feedstock gasifier capable of controlling a composition in produced gas from a gasifier at a desired value. 
     Solution to Problem 
     According to a first aspect of the present invention in order to solve the problems, there is provided a hydrocarbon feedstock gasifier, including: a heat transmission surface provided within a gasification region of a gasifier for generating gasification gas by partially oxidizing a hydrocarbon feedstock; a heat exchanger disposed on a path of a circulation line for a circulation medium circulating within the heat transmission surface and for exchanging the heat of the circulation medium; and a circulation pump for circulating the circulation medium. 
     According to a second aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to the first aspect, wherein the heat transmission surface is a panel type heat transmission surface, and a plurality of heat transmission surfaces is provided along an inner surface of a peripheral wall of the gasifier. 
     According to a third aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to the first aspect, wherein the heat transmission surface is a panel type heat transmission surface, and a plurality of heat transmission surfaces is provided within a space of the gasifier with predetermined intervals. 
     According to a fourth aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to the first aspect, wherein the heat transmission surface is a panel type heat transmission surface, and a plurality of heat transmission surfaces is radially provided within a space of the gasifier with predetermined intervals. 
     According to a fifth aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to any one of claims  1  to  4 , wherein steam is further injected in addition to a normal operating condition of gasification. 
     According to a sixth aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to any one of the first to fourth aspects, wherein the gasifier is a two-stage entrained flow gasifier including a combustor provided on a lower side within the gasifier, and a reductor provided on an upper side of the combustor. 
     According to a seventh aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to the sixth aspect, wherein steam is injected into one of or both the reductor and the combustor in addition to a normal operating condition of gasification. 
     According to an eighth aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to any one of the first to seventh aspects, including: a thermometer that measures a temperature of produced gas at an exit of the reductor of the gasifier; and a controller that controls one of or both a temperature and a flow rate of the circulation medium supplied to the heat transmission surface so that an exhaust temperature of the produced gas is a predetermined temperature. 
     According to a ninth aspect of the present invention, there is provided the hydrocarbon feedstock gasifier according to any one of the first to seventh aspects, including: a gas composition analyzer that measures a gas composition of produced gas at an exit of the reductor of the gasifier; and a controller that controls one of or both a temperature and a flow rate of the circulation medium supplied to the heat transmission surface so that a gas composition of the produced gas is a predetermined composition. 
     Advantageous Effects of Invention 
     According to the invention, a heat transmission surface is provided in a reductor of a gasifier, and a fluid temperature/flow rate of a circulation medium supplied to the heat transmission surface is varied, thereby controlling the amount of heat absorption from produced gas in the reductor of the gasifier. As a result, a temperature of produced gas at an exit of the reductor of the gasifier may be adjusted. By controlling a temperature of produced gas, a composition (H 2 /CO ratio) in the produced gas may be controlled, and thus it is possible to supply gas having a H 2 /CO ratio near 2 or 3 which is required for a methanol synthesis, and methane (CH 4 )-rich substitute natural gas (SNG fuel). Hence, various types of chemical feedstock may be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a hydrocarbon feedstock gasifier according to a first embodiment. 
         FIG. 2  is a diagram illustrated a relation between a temperature of produced gas and a composition (H 2 /CO ratio) in the produced gas. 
         FIG. 3  is a diagram illustrating an example of equipment using the hydrocarbon feedstock gasifier of the embodiment. 
         FIG. 4-1  is a schematic diagram of a hydrocarbon feedstock gasifier according to a second embodiment. 
         FIG. 4-2  is a schematic plan view of the gasifier. 
         FIG. 4-3  is a schematic plan view of the gasifier. 
         FIG. 5  is a schematic diagram of a hydrocarbon feedstock gasifier according to a third embodiment. 
         FIG. 6  is a schematic diagram of a hydrocarbon feedstock gasifier according to a fourth embodiment. 
         FIG. 7  is a schematic diagram of a hydrocarbon feedstock gasifier according to a fifth embodiment. 
         FIG. 8-1  is a diagram illustrating a relation between a temperature of produced gas and a composition (H 2 /CO ratio) in the produced gas based on a steam injection (addition of steam 25%). 
         FIG. 8-2  is a diagram illustrating a relation between a temperature of produced gas and a composition (H 2 /CO ratio) in the produced gas based on a steam injection (addition of steam 70%). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the invention will be described in detail with reference to the drawings. It should be noted that the invention is not limited to an embodiment, and includes a combination of embodiments when a plurality of embodiments is present. In addition, components in embodiments below include a component easily assumed by those skilled in the art, or the substantially same component. 
     First Embodiment 
     A hydrocarbon feedstock gasifier according to an embodiment of the invention will be described with reference to the drawings.  FIG. 1  is a schematic diagram of a hydrocarbon feedstock gasifier according to a first embodiment. 
     As illustrated in  FIG. 1 , a hydrocarbon feedstock gasifier (hereinafter, referred to as a “gasifier”)  10 A according to the embodiment includes a heat transmission surface  15  disposed within a gasification region of a gasifier  13  configured from a pressure vessel for generating produced gas  12  by partially oxidizing a coal  11  which is a hydrocarbon feedstock; a heat exchanger  18  disposed on the path of a circulation line  17  for a circulation medium  16  circulating within the heat transmission surface  15  and for exchanging the heat of the circulation medium  16 ; and a circulation pump  19  for circulating the circulation medium  16 . 
     Herein, the gasifier  10 A according to the embodiment corresponds to a two-stage entrained flow gasifier including a combustor  21  provided on a lower side within the gasifier  13 , and a reductor  22  provided on an upper side of the combustor  21 . 
     Into the combustor  21 , the coal  11  (pulverized coal) is injected through a fuel supply passage  23 A, and a gasifying agent (air)  24  is injected through a gasifying agent supply passage via a burner (not illustrated), and high-temperature combustion gas is generated mainly by a partial combustion of the coal  11 . A collected char  28  contained in the produced gas  12  is separated by a cyclone, a filter, and the like, and is supplied into the combustor  21  by a fuel supply passage  23 C. 
     In addition, a melted slag  25  generated and separated in high-temperature gas within the combustor is adhered to a furnace wall or falls on a furnace bottom, and discharged to a lower side from a slag tap  26 . 
     Further, on a lower side of the slag tap  26 , coolant  27  that cools down the discharged melted slag  25  is stored at the bottom. 
     In addition, the coal  11  (pulverized coal) is injected into the reductor  22  through a fuel supply passage  23 B via a burner (not illustrated), and is mixed with high-temperature combustion gas generated in the combustor  21  within the reductor  22 . As such, a gasification reaction occurs in a high-temperature reduction atmosphere, and the produced gas  12  is obtained. 
     In the embodiment, a plurality of heat transmission surfaces  15  is provided along a wall surface of the reductor  22  of the gasifier  13 . 
     In the embodiment, the heat transmission surface  15  uses a panel type heat transmission surface along an inner surface of an enclosure pipe of the gasifier, and the heat exchanger  18  and the circulation pump  19  for circulating water which is the circulation medium  16  are disposed on the path of a circulation line  17  on the heat transmission surface  15 . 
     A fluid temperature and a circulation flow rate of the circulation medium  16  supplied to the heat transmission surface  15  are controlled by a control device (not illustrated), thereby controlling the amount of heat absorption from the produced gas  12  in the reductor  22  of the gasifier. 
     In the embodiment, the panel type heat transmission surface is used. However, the invention is not limited to a panel type as long as heat of the produced gas  12  and the circulation medium  16  may be exchanged. 
     To control an exhaust temperature of the reductor  22  of the produced gas  12 , one of a method of measuring and controlling a temperature of the produced gas  12  at an exit of the reductor  12  using a thermometer (not illustrated), and a method of measuring and controlling a gas composition of the produced gas  12  at the exit of the reductor  22  using a gas composition analyzer that measures the gas composition may be used. 
     The amount of heat absorption from the produced gas  12  in the reductor  22  is controlled, thereby adjusting a reactant gas temperature of the produced gas  12  at the exit of the reductor  22  of the gasifier  13 . 
     As a result of the temperature control, it is possible to control a composition (H 2 /CO ratio) in the produced gas  12 . 
     Herein, a major reaction in gasification gas proceeds as a reaction formula (1) expressed below. Since the reaction is an exothermal reaction (ΔH 2  98=−9.8 kcal/mol), the reaction of the formula (1) below proceeds to the right side by controlling a reaction temperature, and decreasing the temperature. 
     In this instance, heat is generated as the reaction proceeds. Thus, by performing a heat-absorption control of the amount of heat generation of the reaction, it is possible to efficiently control a composition (H 2 /CO ratio) in the produced gas  12  such that the composition is H 2 -rich. 
       CO+H 2 O→CO 2 +H 2   (1)
 
       FIG. 2  is a diagram illustrated a relation between a temperature of produced gas and a composition (H 2 /CO ratio) in the produced gas. As illustrated in  FIG. 2 , it confirms that a H 2 /CO ratio rises from when a reaction temperature decreases below 1,000° C., and approaches a produced gas composition (H 2 /CO ratio=2.0) necessary for a methanol synthesis reaction (CO+2H 2 →CH 3 OH). 
     A produced gas composition necessary for a methanation reaction (CO+3H 2 →CH 4 +H 2 O) is H 2 /CO ratio=3.0. 
     Therefore, by controlling a gas composition of produced gas that generates produced gas in a gasifier to a hydrogen-rich state necessary for a methanol synthesis and methanation, it is possible to attempt compactification of a CO shift reactor that is separately installed on a slipstream side of the gasifier and includes a CO shift catalyst. 
     In this way, by controlling a composition (H 2 /CO ratio) in the produced gas  12  within the gasifier, it is possible to supply gas having a H 2 /CO ratio near 2 and 3 which is required for a methanol synthesis, and methane (CH 4 )-rich substitute natural gas (SNG fuel). 
     Herein, a chemical reaction formula of the methanol synthesis is expressed by the following formulae (2) and (3). 
       CO+2H 2 →CH 3 OH  (2)
 
       CO 2 +3H 2 →CH 3 OH  (3)
 
     As such, H 2  necessary for the methanol synthesis is (2CO+3CO 2 ). 
     However, in a case where coal is used as a hydrocarbon feedstock, C is great in quantity when compared to H 2 . Thus, the synthesis in the reaction of the formula (2) is set to a main reaction, and a CO shift reactor including a shift catalyst and a de-CO 2  device that removes CO 2  generated in the CO shift reaction are installed in front of an entrance of a methanol synthesis unit, thereby adjusting a gas composition to a composition (H 2 /CO ratio=2.0) suitable for a methanol synthesis. 
     In the embodiment, by varying a temperature/flow rate of a fluid supplied to the heat transmission surface  15 , the amount of heat absorption of the produced gas  12  in the reductor  22  of the gasifier  13  is controlled. 
     By controlling the amount of heat absorption from the produced gas  12  in the reductor  22 , it is possible to adjust a temperature of produced gas at an exit of the reductor  12  of the gasifier  13 , and control a gas composition (H 2 /CO ratio) in the produced gas  12  to a desired ratio. 
       FIG. 3  is a diagram illustrating an example of equipment using the hydrocarbon feedstock gasifier of the embodiment. 
     The produced gas  12  from the gasifier  10 A passes through a gas refinement unit  30  provided as necessary, and then passes through a CO shift reactor  31  and a decarbonation device (not illustrated), and is supplied to a methanol synthesis unit  33  as a gas composition (H 2 /CO ratio=2.0) necessary for a methanol synthesis, thereby obtaining a liquid fuel (methanol)  34 . 
     In addition, similarly, as a gas composition (H 2 /CO ratio=3.0) necessary for a methanation in the CO shift reactor  31 , the produced gas  12  is supplied to a methane synthesis unit  35 , thereby obtaining a gas fuel (synthetic natural gas (SNG))  36 . 
     Further, the refined produced gas  12  is supplied to a gas turbine combustion device  41  to drive a gas turbine  42 , thereby generating electricity  44  by a generator  43 . 
     The obtained methanol and methane may be used as a fuel, and may be used as a starting material of a chemical feedstock. In addition, the liquid fuel  34  may be used as an auxiliary fuel of the gasifier or a fuel at the time of startup. 
     In the embodiment, the two-stage entrained flow gasifier including a combustor and a reductor provided on the upper side thereof is given as an example. However, the invention is not limited thereto, and may be applied to a one-stage entrained flow gasifier and the like. 
     In addition, various carbon feedstocks such as coal (pitch coal, subbituminous coal, and lignite (low grade coal)), biomass, and petroleum coke may be used as the hydrocarbon feedstock. 
     Second Embodiment 
     A hydrocarbon feedstock gasifier according to an embodiment of the invention will be described with reference to the drawings.  FIG. 4-1  is a schematic diagram of a hydrocarbon feedstock gasifier according to a second embodiment. 
     As illustrated in  FIG. 4-1 , a hydrocarbon feedstock gasifier  10 B according to the embodiment is not provided along a peripheral wall as in the first embodiment, and a heat transmission surface  15  is suspended by a suspension member (not illustrated). 
       FIGS. 4-2  and  4 - 3  are schematic plan views of the gasifier. 
     In  FIG. 4-2 , a plurality of suspension type heat transmission surfaces  15  is disposed with predetermined intervals within a gasifier  13 . 
     In  FIG. 4-3 , a plurality of suspension type heat transmission surfaces  15  is radially disposed within the gasifier  13 . 
     A temperature of a cross-sectional surface of the gasifier may be more uniformized when compared to a case of being provided along the peripheral wall of the first embodiment. 
     Further, the heat transmission surface may be increased when compared to a case of being provided along the peripheral wall, and thus the amount of heat absorption may be easily controlled. As a result, a reactant gas temperature at an exit of the gasifier may be easily controlled. 
     A disposition of the plurality of suspension type heat transmission surfaces  15  is not limited to the embodiment. 
     Third Embodiment 
     A hydrocarbon feedstock gasifier according to an embodiment of the invention will be described with reference to the drawings.  FIG. 5  is a schematic diagram of a hydrocarbon feedstock gasifier according to a third embodiment. 
     As illustrated in  FIG. 5 , a hydrocarbon feedstock gasifier  10 C according to the embodiment further supplies steam  50  into a reductor  22  via a steam supply passage (not illustrated) in the gasifier  10 A of the first embodiment. 
     When the steam  50  is injected in addition to a normal operating condition (the amount of coal, and a gasifying agent (air, oxygen, steam, CO 2 , and the like)) in the gasifier  10 A of the first embodiment, it is possible to increase a gas composition H 2 /CO ratio in the produced gas  12 . 
     An independent steam injection to the reductor  22  or a mixed injection to a coal nozzle may be used as an injection of the steam  50 . Further, a combination injection of the independent injection and the mixed injection may be used. 
       FIGS. 8-1  and  8 - 2  are diagrams illustrating a relation between a temperature of produced gas and a composition (H 2 /CO ratio) in the produced gas based on a different in amount of steam injection. Steam accounting for 25% of produced gas is supplied in  FIG. 8-1 , and steam accounting for 70% of produced gas is injected in  FIG. 8-2 . 
     In this way, it confirms that a composition approaches a produced gas composition (H 2 /CO ratio=2.0) necessary for a methanol synthesis, and a produced gas composition (H 2 /CO ratio=3.0) necessary for a methanation by increasing the amount of the injected steam  50  even when a rise degree of a H 2 /CO ratio is on a high-temperature side. 
     Fourth Embodiment 
     A hydrocarbon feedstock gasifier according to an embodiment of the invention will be described with reference to the drawing.  FIG. 6  is a schematic diagram of a hydrocarbon feedstock gasifier. 
     As illustrated in  FIG. 6 , a hydrocarbon feedstock gasifier  10 D according to the embodiment further supplies steam  50  into a combustor  21  via a steam supply passage (not illustrated) in the gasifier  10 A of the first embodiment. 
     Steam is injected into the reductor  22  in the third embodiment, however the steam  50  is injected into the combustor  21  in the embodiment, and thus may be injected into the gasifier  10 D as higher-temperature (high-activation) steam. As a result, a gas composition H 2 /CO ratio of the produced gas  12  may be further increased when compared to the third embodiment. 
     Fifth Embodiment 
     A hydrocarbon feedstock gasifier according to an embodiment of the invention will be described with reference to the drawing.  FIG. 7  is a schematic diagram of a hydrocarbon feedstock gasifier. 
     As illustrated in  FIG. 7 , a hydrocarbon feedstock gasifier  10 E according to the embodiment supplies steam  50  into a combustor  21  and a reductor  22  via a steam supply passage (not illustrated) by combining the third embodiment and the fourth embodiment. 
     In the embodiment, an operative range as a gasifier is wide, and a gas composition H 2 /CO ratio of produced gas  12  may be increased. 
     As described with the embodiments in the foregoing, in the invention, the heat transmission surface  15  is provided in the reductor  22  of the gasifier  13 , and a fluid temperature/flow rate of the circulation medium  16  supplied to the heat transmission surface  15  is varied, thereby controlling the amount of heat absorption from the produced gas  12  in the reductor  22  of the gasifier  13 . As a result, a temperature of the produced gas  12  at the exit of the reductor  22  of the gasifier  13  may be adjusted. 
     In addition, by controlling a temperature of the produced gas  12 , a composition (H 2 /CO ratio) in the produced gas  12  may be controlled, and thus it is possible to supply gas having a H 2 /CO ratio near 2 and 3 which is required for a methanol synthesis, and methane (CH 4 )-rich substitute natural gas (SNG fuel) resulting from a methanation reaction. Hence, various types of chemical feedstock may be provided. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10 A to  10 E HYDROCARBON FEEDSTOCK GASIFIER (GASIFIER) 
               11  COAL 
               12  PRODUCED GAS 
               15  HEAT TRANSMISSION SURFACE 
               16  CIRCULATION MEDIUM 
               17  CIRCULATION LINE 
               18  HEAT EXCHANGER 
               19  CIRCULATION PUMP