Abstract:
Described is a biogas to liquid fuel converter and method of use which includes a biogas cleaning system which can be obtained from a landfill of sewage digester which further includes a cargo container housing the syngas production system and methanol synthesis devices employed in converting biogas to methanol.

Description:
BACKGROUND 
     Generally, biogas to liquid fuel converters utilize very large scale processes requiring large amounts of equipment and large amounts of investment capital. These converters require very large amounts of bio-gas at a site to justify construction and operation of large scale methanol production. The Lurgi process for low-pressure crude methanol production from bio-gas is one example of a very large scale operation. Reduction of the size of an operation using the Lurgi process or other known processes is not possible by substituting smaller components for larger components. A new process, with components different than currently utilized components, is necessary to convert biogas into methanol. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     In an embodiment, there is provided a biogas to liquid fuel converter, comprising a gas cleaning system having a condensate separation vessel configured to remove moisture from a gas, and a polypropylene filter to remove particles; a syngas production system configured to receive the gas from the gas cleansing system, the syngas production system having a catalyst configured to produce hydrogen and carbon monoxide, and a flash tank to condense methanol from the gas; and a methanol synthesis system having a methanol synthesis reactor having catalysts configured to react with the gas at a temperature and a pressure to produce methanol. 
     In another embodiment, there is provided a biogas to liquid fuel converter, comprising a gas cleaning system; and a cargo container in fluid communication with the gas cleaning system, the cargo container comprising a syngas production system configured to receive the gas from the gas cleansing system, the syngas production system having a syngas reactor with a gas-to-gas re-heater, a heat exchanger, a syngas reactor, a catalyst configured to produce hydrogen and carbon monoxide, and a flash tank to condense methanol from the gas; and a methanol synthesis system having a methanol synthesis reactor having catalysts configured to react with the gas at a temperature and a pressure to produce methanol. 
     In yet another embodiment, there is provided a method of making a liquid fuel comprising converting one of a landfill gas and a sewage digester gas using a biogas to liquid fuel converter, comprising a gas cleaning system; and a cargo container in fluid communication with the gas cleaning system, the cargo container comprising a syngas production system configured to receive the gas from the gas cleansing system, the syngas production system having a syngas reactor with a gas-to-gas re-heater, a heat exchanger, a syngas reactor, a catalyst configured to produce hydrogen and carbon monoxide, and a flash tank to condense methanol from the gas; and a methanol synthesis system having a methanol synthesis reactor having catalysts configured to react with the gas at a temperature and a pressure to produce methanol. 
     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Illustrative embodiments of the invention are illustrated in the drawings, in which: 
         FIG. 1   a  illustrates a schematic representation of an exemplary embodiment of a gas cleaning system; 
         FIG. 1   b  illustrates a schematic representation of an exemplary embodiment of a syngas production system; and 
         FIG. 1   c  illustrates a schematic representation of an exemplary embodiment of a methanol synthesis system. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are described more fully below in sufficient detail to enable those skilled in the art to practice the system and method. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense. 
     This invention cleans, and converts bio-gas into liquid methanol at much lower temperature, pressure, with significantly lower water energy use than is current, and on a micro-scale that is many times smaller than any current technology allows. 
     The system is designed to be used with landfill gas or sewage digester gas, unique feed sources for conversion to liquid fuels, or other bio-gases (i.e. coal bed methane, low heating value natural gas). Other fuels that the system may produce include, but are not limited to: distillate having up to 75% diesel and no impurities; di-methyl ether for use in the chemical industry; methanol for use as a fuel or chemical intermediate; ethanol for use as a fuel or chemical intermediate; mixed alcohols-ethanol, methanol, butanol for higher octane fuels; chemical intermediates such as acrylates for polymer production; jet kerosene; and hydrogen. 
     It is a fraction of the size of any known gas to liquid plant; it is dramatically smaller than any comparable system because it is radically more efficient than any such system, requiring significantly less energy and water to be productive (and profitable). It is this ultra-reduction in scale that has made landfill and sewage gases viable—even the largest known landfills or sewage plants are not viable for fuel production (economies of scale). We are viable for app. 80% of all landfills in US. 
     The system may be installed in a shipping container for safety, noise reduction, and ease of transport. This may provide a form of mass production able to be transported where required because of the tiny scale. 
     In an embodiment, the system has 3 main components (1) a gas cleaning system, (2) a syngas production system, and (3) methanol synthesis system. 
     Fuel comes from the fuel supply, e.g. landfill, sewage plant digester, or bio gas from natural sources. We believe that our use of feed supplies such as landfill and sewage digester gas for the purpose of conversion to liquid fuels (technically alcohols) is unique. 
     The gas cleaning system is essential to the overall gas to liquid system. This cleaning system protects the syngas reaction from being poisoned, which would deactivate the catalyst within a few hours. 
     Gas Cleaning is achieved by first using a condensate separation vessel to remove larger particles of moisture, then a polypropylene filter to remove foreign particles down to 4 microns. After pre-cleaning the gas is the compressed to 7 Bar, after compression the gas is cooled down to 10 Degrees C. to remove the remainder of the moisture, then the gas is fed back through a re-heater and fed into the first media tank, where most of the siloxanes and other contaminants are removed, the gas exits out the top and is fed into the second media tank to remove any remaining siloxanes and contaminants. Tests are carried out to ensure the gas is within limits and siloxanes and H 2 S are not detectable (ND). 
     The gas is then fed into the syngas reactor. Syngas production is where the bio gas (60% CH4 40% CO2) is converted into a mixture of H 2  and CO. It is first preheated to 400 Degrees in a gas to gas re-heater, steam is then added, and then it enters the main heat exchanger and is heated to 900 degrees C. The heated gas is then fed into the syngas reactor and reacted over a catalyst to produce H 2  and CO. The gas is first cooled in the gas to gas re-heater, this cools the gas (and preheats the incoming gas), it is then fed into a gas to water heat exchanger and cooled to below 50 C, and moisture is removed with a cyclone filter. It is then fed into the gas compressor and compressed to 20 Bar, the gas is heated to 250 C. and fed into the methanol synthesis reactor, it leaves the reactor and is cooled to 25 degrees, it the is fed into a flash tank, a pressure drop of 15 bar is needed to condense the methanol from the gas, it is collected at the bottom of the tank and drained for final distillation. The left over gas mixture is fed back into the main manifold and used in the power plant. 
     For methanol synthesis, the syngas is then compressed to 20 bar and fed into the methanol synthesis reactor. The pressure is then dropped back to 5 bar and liquid methanol is separated. The conversion of landfill gas happens at just above atmospheric pressure, so no compressor that uses power in turn saves energy, and we re-use the heat from the first reaction to preheat the incoming gas, by using Steam CO2 reforming at low pressure is our main saving in energy, water can be recycled and used again. Catalysts are used that react at low pressure and temperature, which are included the second stage, 20 bar and 230 degrees, and which are much lower than conventional systems 
     In an embodiment, there may be provided a gas cleaning system  5  (see  FIG. 1   a ); a syngas production system  10  (see  FIG. 1   b ); and a methanol synthesis system  15  (see  FIG. 1   c ). 
     With reference to  FIG. 1   a , and in an embodiment, there may be provided a gas cleaning system  5  external to the remainder of the gas-to-liquid system (referred to as a “GTL system”) inside a shipping container or other modular container. In an embodiment, cleaning system  5  is separate due to size and may be skid mounted with a couple of large media tanks. Generally, the only part of the gas-to-liquid system that needs to be replaced is the catalysts, which have a 3 to 5 year life expectancy. Gas cleaning system  5  uses a media that can be regenerated every 3 months. 
     Still looking at  FIG. 1   a , there may be provided a condensate separation vessel  20  to receive methane gas from a transport pipe  25  into a side entry inlet  30 . Condensate separation vessel  20  may be provided as a vertical tank sized 4000 mm by 1500 mm. Condensate separation vessel  20  may be made from stainless steel. Side entry inlet  30  may be flanged and have a width of 300 mm. Side entry inlet  30  may be located about 2000 mm from bottom of the tank forming condensate separation vessel  20 . A side exit  35  may be provided from condensate separation vessel  10 . Side exit  35  may be located about 500 mm from top of the tank forming condensate separation vessel  20 . Side exit  35  may be flanged and have a width of 300 mm. 
     A gas filter  40  may be provided in fluid connection to side exit  35  of the condensate separation vessel  10 . A transport pipe  45  may be disposed between gas filter  40  and condensate separation vessel  20 . Gas filter  40  may include a stainless steel filter box having dimensions of a length of 500 mm by a width of 1000 mm by a height of 750 mm. The stainless filter box of the gas filter  40  may include a 4-micron polypropylene filter. In an embodiment, a gas inlet  50  of gas filter  40  has a width of 300 mm and a gas outlet  55  of gas filter  40  has a width of 200 mm. 
     A gas booster  60  may be provided in fluid connection to gas filter  40 . Gas booster  60  may include a gas compressor, e.g., a 90SCMH Hitachi gas compressor. A transport pipe  65  may be disposed between gas booster  60  and gas filter  40 . In an embodiment, a gas inlet  70  of gas booster  60  has a width of 200 mm and a gas outlet  75  of gas booster  60  has a width of 50 mm. 
     A gas reheater  80  may be provided in fluid connection to gas booster  60 . A transport pipe  85  may be disposed between gas reheater  80  and gas booster  60 . Gas reheater  80  may be formed include a tank sized 450 mm by 1500 mm. In an embodiment, gas reheater  80  includes a stainless steel shell and tube heat exchanger  95  formed of SS 304L (an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength, and ductility.) In an embodiment, an inner tube gas inlet  90  of gas reheater  80  is flanged and has a width of 50 mm and an inner tube gas outlet  100  of gas reheater  80  is flanged and has a width of 50 mm. An outer tube (i.e., shell) gas inlet  105  of gas reheater  80  is flanged and has a width of 50 mm and an outer tube (i.e., shell) gas outlet  110  of gas reheater  80  is flanged and has a width of 50. 
     A gas to water heat exchanger  115  may be provided as a tank sized 450 mm by 1500 mm. Gas to water heat exchanger  115  may be made from 304 stainless steel as a tube heat exchanger. A transport pipe  120  may be disposed in fluid connection between gas reheater  80  and gas to water heat exchanger  115 . A side entry inlet  125  may be provided into gas to water heat exchanger  115 . Side entry inlet  125  may be flanged and have a width of 50 mm. A side outlet  130  may be provided from gas to water heat exchanger  115 . Side outlet  130  may be flanged and have a width of 300 mm. Water connections  135  may be provided between gas to water heat exchanger  115  and a chiller  140  to circulate water or other fluid to cool the methane gas provided through gas to water heat exchanger  115 . In an embodiment, this circulated water may be configured to flow at a rate of about 90 liters per minute. Chiller  140  may include, but is not limited to, a Trane brand 90 liter per minute chiller device. In an embodiment, chiller  140  may operate at about 10 degrees C. to provide cooled water to the tube heat exchanger  115 . A media tank  145  (also referred to as media tank  1 ) may be provided as a 304 stainless steel tank sized 650 mm by 3000 mm. A transport pipe  150  may be disposed in fluid connection between gas to water heat exchanger  115  and media tank  145 . An inlet connection  155  may be provided into media tank  145 . Inlet connection  155  may be flanged and may have a width of 50 mm. An outlet connection  160  may be provided from media tank  145 . Outlet connection  160  may be flanged and have a width of 50 mm. Media tank  145  contains an area of carbon granules of about 2.5 mm by 5 mm. Media tank  145  must include about 1 gram of activated carbon covering a surface area in excess of 500 m 2 . 
     A media tank  170  (also referred to as media tank  2 ) may be provided as a 304 stainless steel tank sized 650 mm by 3000 mm. A transport pipe  175  may be disposed in fluid connection between media tank  145  and media tank  170 . An inlet connection  180  may be provided into media tank  145 . Inlet connection  180  may be flanged and may have a width of 50 mm. An outlet connection  185  may be provided from media tank  170 . Outlet connection  185  may be flanged and have a width of 50 mm. Media tank  170  contains an area of carbon granules of about 2.5 mm by 5 mm. Media tank  170  must include about 1 gram of activated carbon covering a surface area in excess of 500 m 2 . A line  190  may be in fluid connection with outlet connection  185  to output  195  of gas cleaning system  5 . 
     With reference to  FIG. 1   b , and in an embodiment, there may be provided syngas production system  10  within a shipping container or other modular container. Syngas production system  10  may include piping all formed from 50 mm schedule 80 304L stainless steel. An input line  200  may be in fluid connection with line  190  from gas cleaning system at output  195 . A gas isolation valve  205  may be provided prior to a line  210  to a gas regulator  215 . Gas isolation valve  205  may be a 50 mm pneumatically controlled valve. Gas regulator  215  may reduce the pressure of the cleaned methane gas from 7 Bar to 1 Bar into a line  220 . Gas regulator  215  may include a 50 mm flanged connection with line  210  and line  220 . 
     A gas reheater  225  may be provided in fluid connection with line  220  at inlet  230  with a 50 mm flanged connection and include an outlet  235  with a 50 mm flanged connection to line  240 . Gas reheater  225  may be formed of a tank of stainless steel 304 forming a shell and tube heat exchanger having dimensions with a diameter of 300 mm by a length of 2400 mm. 
     An electric heat exchanger  245  may be provided in fluid connection with gas reheater  225  through line  240  to an inlet  250  having a 50 mm flanged connection. An outlet  255  may be provided with a 50 mm flanged connection. Electric heat exchanger may operate over a range of 0 to 900 Degrees C. Electric heat exchanger  245  may be formed of 304L stainless steel and have dimensions with a diameter of 300 mm by a length of 2400 mm. 
     A reactor  260  (also referred to as a reformer  1 ) may be provided in fluid connection to electric heat exchanger  245  with a line  265 . An inlet  270  with a flanged connection with a width of 100 mm may be provided between reactor  260  and line  265 . An outlet  275  with a flanged connection with a width of 100 mm may be provided from reactor  260 . Reactor may include a stainless steel 304L tube in a U configuration, which is generally shown as a pressure vessel. A transport pipe or line  280  may extend from outlet  275  to a gas inlet  285  at gas reheater  225 . 
     An outlet  290  may be in fluid communication from a water-cooled heat exchanger  295  to gas reheater  225  with a transport pipe or line  300 . Water-cooled heat exchanger  295  may include a 50 mm flanged connection  305  to line  300 . Water-cooled heat exchanger  295  may include a pipe having a width of 100 mm. Water flow through the water-cooled heat exchanger  295  may proceed at a rate of 90 liters per minute. Water-cooled heat exchanger  295  may have dimensions of a diameter of 300 mm by a length of 2400 mm and may be formed of stainless steel 304L. Water-cooled heat exchanger  295  cools the gas from about 800 degrees C. to about 50 degrees C. from inlet  305  to gas outlet  310 . A transport pipe or line  315  leads from gas outlet  310  to methanol synthesis system  15 . 
     A chiller  320  in fluid connection with water-cooled heat exchanger  295  may include a chilled water tank  325  receiving water out through a transport pipe or line  330  from an outlet  335  in connection with water-cooled heat exchanger  295 . In an embodiment, chiller  320  may include a Trane brand 90 liter per minute chiller device. An inlet  340  may connect line  330  to chilled water tank  325 . An outlet  345  may connect a line  348  to chilled water tank  325 . An inlet  350  may connect line  348  to chiller  320 . An outlet  355  may connect chiller  320  to an inlet  360  of water-cooled heat exchanger  295  and to a transport pipe or line  365  to methanol synthesis system  15 . 
     With reference to  FIG. 1   c , and in an embodiment, methanol synthesis system  15  may include all pipe work of stainless steel 304L having a diameter of 50 mm. 
     A gas compressor  375  may be provided in fluid connection with a line  315  from syngas production system  10 . Gas compressor  375  may include a Corken brand gas compressor operating at 60 standard cubic meters per hour (SCMH), operating at a pressure of 25 Bar, and being water cooled. An inlet  380  of gas compressor  375  allows receipt of water from line  365 A, which is connected with fluid line  365  from syngas production system  10 . An outlet  385  of gas compressor  375  allows return of water through line  370 A, which is connected to fluid line  370  returning to syngas production system  10 . 
     An electrical heat exchanger  390  may have an inlet  395  to receive gas and an outlet to direct heated gas into a transport pipe or a line  405 . The heated gas may have a temperature of about 150 degrees C. to 250 degrees C. 
     A synthesis reactor  410  (also referred to as a reformer  2 ) may include an inlet  415  in fluid communication with line  405  to receive the heated gas. Another inlet  425  may be in fluid communication with line  365  of syngas production  10  to receive chilled water into synthesis reactor  410  from chiller  355 . An outlet  430  may be in fluid communication with synthesis reactor  410  to provide gas into a pressure shell and tube heat exchanger  435  from transport pipe or line  440  through inlet  445 . Synthesis reactor  410  may be dimensioned at a size of 400 mm by 1600 mm. (This size ratio is proven technology.) 
     Pressure shell and tube heat exchanger  435  may be constructed of stainless steel 304L material and operate at a pressure of 30 Bar. An inlet  445  for gas into pressure shell and tube heat exchanger  435  may include a 50 mm flanged connection. Inlet  455  may be in fluid connection with line  440  from synthesis reactor  410 . An outlet  450  for gas out of pressure shell and tube heat exchanger  435  may include a 50 mm flanged connection. 
     A pressure shell and tube heat exchanger  455  may be constructed of stainless steel 304L material and operate at a pressure of 30 Bar. An inlet  460  for gas into pressure shell and tube heat exchanger  455  may include a 50 mm flanged connection. A transport pipe or line  462  may be in fluid connection between outlet  450  of pressure shell and tube heat exchanger  435  and pressure shell and tube heat exchanger  455 . An outlet  465  for gas out of pressure shell and tube heat exchanger  455  may include a 50 mm flanged connection. 
     For circulating cooling water between pressure shell and tube heat exchanger  435  and pressure shell and tube heat exchanger  455 , a transport pipe or line  470  may be provided in fluid communication between these exchangers through water outlet  475  into pressure shell and tube heat exchanger  435  from water inlet  480  from pressure shell and tube heat exchanger  455 . Another transport pipe or line  485  may be provided in fluid communication between these exchangers through water inlet  490  from pressure shell and tube heat exchanger  455  into water outlet  495  and into pressure shell and tube heat exchanger  435 . Pressure shell and tube heat exchanger  435  may cool water from 250 degrees C. to 50 degrees C. Pressure shell and tube heat exchanger  455  may cool water from 50 degrees C. to 20 degrees C. 
     A second chiller  500  (also referred to as a chiller  2 ) may be configured with a chilled water tank  505  to receive water through a transport pipe or line  510  from an outlet  515  in pressure shell and tube heat exchanger  435 . An inlet  520  in fluid connection with line  510  provides water to chilled water tank  505 . A second transport pipe or line  525  may provide a fluid connection between an outlet  530  of chilled water tank  505  to an inlet  535  of chiller  500 . A third transport pipe or line  540  may provide a fluid connection between an outlet  545  of chiller  500  and an inlet of pressure shell and tube heat exchanger  435 . Chiller  500  may include a Trane brand 90 liter per minute chiller. 
     A flash tank  555  may be formed from stainless steel 304L. An input line  560  may extend in fluid communication from gas outlet  465  to flash tank  555 . An expansion valve  565  may be configured between input line  560  and flash tank  555  to provide a drop in pressure of the water from 25 Bar to 5 Bar pressure. 
     A gas vent line  570  extends between flash tank  555  and includes a valve  575  prior to gas vent  580 . In one embodiment, expansion valve  565  drops the pressure very quickly into a larger vessel, and, in turn, the gas vapors condense and form droplets of liquid. Vent  580  is for either venting to atmosphere or returning to the main header. 
     A storage tank line  585  extends between flash tank  555  and a methanol storage tank  590 . In an embodiment, methanol liquid fuel may be removed from methanol synthesis system  15  from the methanol storage tank. 
     A valve  595  may be disposed within a water line  600  extending away from flash tank  555 . Water line returns excess water from flash tank  555  to a water-cooled heat exchanger  295  of syngas production system  10  through line  315 . 
     In reactor  260 , reactor  410 , or both, catalysts have included an experimental Nano catalyst that worked very well but was prone to coking and deactivation so it was decided to use a commercially available CAT. Both the CAT surgery are commercially available with unsized nanoscale particles. 
     Reactor  260  (also referred to as reformer  1 ) utilized the ReforMax® 330 brand product catalyst supplied from Sudchem. Reactor  410  (also referred to as reformer  2 ) utilized the UNI CAT-MS-900 brand product catalyst, which is the next generation UNICAT CuO/ZnO Low Temperature Active Methanol Synthesis catalyst. Other catalysts may also work to convert methane gas to liquid methanol fuel. 
     The combination of gas cleaning system  5 , syngas production system  10 , and methanol synthesis system  15  are operable at low temperature and pressure so as to reduce both manufacturing cost and operational cost for producing liquid methanol. 
     A number of operating parameters must be met for each of gas cleaning system  5 , syngas production system  10 , and methanol synthesis system  15  to work so as to produce liquid methanol. The main operating parameters that must be met are temperatures and pressures. These main parameters are provided by the syngas production system  10  and methanol synthesis system  15  to work so as to produce liquid methanol. Gas cleaning system  5  provides the necessary methane gas, which must be extremely clean. 
     Catalysts only operate at specific temperatures and pressures which are provided by the syngas production system  10  and methanol synthesis system  15   
     For high temperature operation and durability, the various parts described hereinabove may be fabricated from stainless steel 304L or higher equivalent properties for high temperature operation. 
     Although the above embodiments have been described in language that is specific to certain structures, elements, compositions, and methodological steps, it is to be understood that the technology defined in the appended claims is not necessarily limited to the specific structures, elements, compositions and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed technology. Since many embodiments of the technology can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.