EP2049647A2

EP2049647A2 - Gas distributor for a stacked particle bioreactor

Info

Publication number: EP2049647A2
Application number: EP07805156A
Authority: EP
Inventors: Alan Eric Norton; Jeffrey Todd Harvey; Michael John Gunn
Original assignee: Geosynfuels LLC
Current assignee: Geosynfuels LLC
Priority date: 2006-07-14
Filing date: 2007-07-13
Publication date: 2009-04-22
Also published as: CL2007002072A1; MX2009000501A; CA2657501A1; WO2008010175B1; WO2008010176A3; PE20080383A1; UY30487A1; AU2007274621A1; WO2008010175A2; IL196492A0; SG175623A1; WO2008010175A3; BRPI0714506A2; AR062070A1; WO2008010176A2; AR062066A1

Abstract

The invention relates to gas distributor (1) for a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material comprising a pipe having a series of apertures (3) through the wall of the pipe, with the series of apertures configured operatively to face downwards in the stacked particle bioreactor, and to be located in an indentation (2) in the outer wall of the pipe. The invention also extends to a stacked particle bioreactor, method of forming a stacked particle bioreactor, and a method of producing gaseous fuel from biodegradable carbonaceous material using a stacked particle which utilizes such a gas distributor.

Description

GAS DISTRIBUTOR FOR A STACKED PARTICLE BIOREACTOR

FIELD OF THE INVENTION

This invention relates to a gas distributor for a stacked particle bioreactor in which organic carbonaceous material is biologically treated to produce fuel.

BACKGROUND TO THE INVENTION

The demand for naturally occurring fuels is likely to exceed the world supply in the near future. Additionally, the natural distribution of fuels throughout the world is disproportionate. The development and use of synthetic fuels (synfuels), those derived from non-traditional feed stocks, is increasing. The production of ethanol, methane and other hydrocarbon products from carbonaceous material is increasing.

One answer to the problem is the production of synfuels through stacked particle (heap) bioreactors. These bioreactors operate on the principle of stacking particles of biodegradable carbonaceous material and providing optimal living conditions for the microorganisms, which are either naturally present or specifically added microorganisms to biologically treat the stacked particles. The biologically treated carbonaceous material produces synfuels which may include synthetic petroleum, alcohol, and/or a gaseous fuel.

The synfuel is recovered from the stack and processed further depending on its quality and purity. The synfuels may be in liquid form, such as synthetic petroleum or alcohol, or in gas form such as a gas which includes methane or alcohol. The recovery of gaseous synfuels is done by means of a gas collector system which is placed proximate the top of the stack. The recovery of liquid synfuels is done by means of a collection system located at the bottom of the stack.

The biological treatment of the carbonaceous material in such a stack may be aerobic and/or anaerobic. In the case of aerobic treatment the microorganisms utilize oxygen and oxygen is preferentially added to supplement depleted oxygen to optimize the performance of the microorganisms, at least to the extent that it is dependant on the presence of oxygen.

In the case of anaerobic treatment the microorganisms operate in the absence of oxygen, and oxygen is preferentially removed to optimize the performance of the microorganisms, at least to the extent that it is dependant on the absence of oxygen. Inert gas is circulated through the stack via the gas distribution/collection system and is either a recycle of the process effluent gas such as carbon dioxide or an externally supplied inert gas.

To add oxygen to an aerobically treated bioreactor, oxygen or air is purged into a stack, typically from the bottom of the stack. Depending on the gas permeability of the stack, additional purge lines may also be located on levels higher than the bottom, to optimize the distribution of the purged oxygen or air through the stack. This allows oxygen and air to be added to the stack as needed to optimize the performance of the microorganisms. The need for this may be verified by means of strategically placed sensors in the stack or to the outputs from the stack.

To remove oxygen from the stack, which is needed to optimize the performance of anaerobic treatment of the carbonaceous material in the stack, oxygen is purged from the stack. The purging is done by using, for example, argon, nitrogen, carbon dioxide, ammonia, or hydrogen gas. At the same time the stack is covered with a gas impermeable barrier which prevents oxygen from being taken up into the stack through its surface.

In some processes a stack is initially treated aerobically and then switched to anaerobic treatment after a while. To switch from aerobic to anaerobic treatment, anaerobic microorganisms have to be added to the stack. This is done by means of inoculation.

Inoculation can take many forms. During the initial construction of the bioreactor, inoculation can take the form of spraying the particles which form the stack with a fluid which contains the microorganisms as they are laid down, or by preparing layer and then spraying its surface and repeating this process to build the bioreactor. These examples of inoculation are only effective when the bioreactor is constructed. Once the bioreactor has been constructed inoculation is done by irrigation with fluid which contains the microorganisms. The inoculation fluid may also contain nutrients for the microorganisms.

The inoculation by emitters may be done on the surface of the stack, or from below the surface to optimize the spread of the inoculum.

From the forgoing it should be clear that there are several fluid inputs and outputs to the system which comprises a stacked particle bioreactor.

The fluid inputs include gas which is forced or allowed into the stack from below. This includes oxygen and air which are used during aerobic treatment and argon, nitrogen, carbon dioxide, ammonia, or hydrogen gas which are used during anaerobic treatment. The gas is pumped or allowed under atmospheric pressure into the stack through the gas purge lines.

The fluid inputs also include liquid with which the stack is irrigated. This typically comprises water and stack products which also contains microorganisms and nutrients. The liquid irrigation takes place from above or from within the stack.

The fluid outputs include gas synfuels, for example those containing methane, that rise through the stack and are collected by the gas collector system located proximate the top of the stack. The reversing of the gas flow directions is also facilitated in the bioreactor.

The fluid outputs also include the liquid synfuels which drain through the stack and are collected at the bottom.

It should therefore be clear that the system includes fluids that move either up or down in the stack. To optimize the performance of the process, the fluid flows must be balanced based on heat generation.

The design, operation, and advantages of one such system have been described in detail in published patent application US2006/0223154A1 .

A problem with the purge pipes located at the bottom of the stack is that random alignment of the material used to stack the bioreactor may block a hole or restrict flow of gas from the hole. Also, liquid synfuels which drain through the stack flow over such purge pipes near or over the holes therein. Since the environment near each hole is evaporative due the inflow of gas from the purge pipe, precipitates may form due to evaporation of liquid and such precipitates may block the hole.

Another problem is that if the gas flow through the purge pipe is stopped, as may be the case when aerobic treatment takes place and the stack has been initially purged of oxygen and air and covered, there is an increased chance of flooding of the pipes with liquid synfuels draining through the stack.

Once a purge pipe has been so blocked or flooded it is very difficult, if not impossible, to clear it without removing it from the stack. It is not possible to remove a pipe without at least disturbing or damaging the stack, and most likely not without destroying the fine balance within the bioreactor. Since these bioreactors are constructed to operate for several years a blocked or flooded pipe normally results in loss of fluid input at the specific point so blocked or flooded.

In this specification the term "dry-shadow" refers to the area underneath a gas distributor in a stacked particle bioreactor that remains substantially dry despite the flow of liquid down through the stack. The size of the dry shadow depends on a number of factors, including the diameter of the pipe which forms the gas distributor, the hydraulic conductivity of the drain material in the stack, and the amount of liquid that drain through the stack.

OBJECT OF THE INVENTION

It is an object of the invention to provide a gas distributor for a stacked particle bioreactor which at least partly overcomes the abovementioned problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a gas distributor for a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material comprising a pipe having a series of apertures through the wall of the pipe, and for at least one aperture to be located in an indentation in the outer wall of the pipe.

There is further provided for the pipe to include a continuous indentation, preferably for all the apertures to be located in the continuous indentation, and more preferably for the continuous indentation to extend longitudinally along the outer wall of the pipe. According to a further feature of the invention there is provided for the pipe to include an endless circumferential indentation, preferably for a plurality of endless circumferential indentations to be spaced apart along the pipe, alternatively for the pipe to include a helical indentation, and for a plurality of apertures to be located in the circumferential indentations.

There is further provided for the gas distributor to include a perforated cover over each aperture, and preferably for a single cover over the continuous indentation and circumferential indentations respectively.

There is still further provided for the gas distributor to be configured for the series of apertures to operatively face downwards in a stacked particle, preferably in the dry-shadow of the pipe.

According to an alternative feature of the invention there is provided a gas distributor for a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material comprising a pipe having a series of apertures through the wall of the pipe, and for the series of apertures to be configured operatively to face downwards in a stacked particle, preferably in the dry-shadow of the pipe.

There is yet still further provided for the gas distributor to include a series of apertures which extend longitudinally along the pipe in a line which is orientated between about 0° and 45° degrees from the vertical along the circumference of the pipe.

There is also provided for the gas distributor which includes the endless circumferential indentation to include two apertures spaced apart by between about 0° and 45° degrees from the vertical along the circumference of the pipe, and for each of these apertures to be part of a series of apertures which extend longitudinally along the pipe in a line which is orientated between about 0° and 45 " degrees from the vertical along the circumference of the pipe.

There is still further provided for the invention to extend to a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material which includes a gas distributor as defined above, a method of forming a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material which includes installing a gas distributor as defined above in the stacked particle bioreactor, and a method of producing gaseous fuel from biodegradable carbonaceous material using a stacked particle bioreactor which includes the step of introducing gas into the stacked particle bioreactor through a gas distributor as defined above. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described by way of example only and with reference to the accompanying drawings in which:

Figure 1 A is a perspective view of a first embodiment of a gas distributor according to the invention which comprises a pipe with a continuous longitudinal semi circular indentation within which a plurality of apertures is located; Figure 1 B is an end view of the pipe of Figure 1 A; Figure 1 C is a bottom plan view of the pipe of Figure 1 A;

Figure 2A is a perspective view of a second embodiment of a gas distributor according to the invention which comprises a pipe with a plurality of longitudinally arranged smooth indentations within each of which an aperture is located; Figure 2B is an end view of the pipe of Figure 2A; Figure 2C is a bottom plan view of the pipe of Figure 2A;

Figure 3A is a perspective view of a third embodiment of a gas distributor according to the invention which comprises a pipe with a continuous longitudinal rectangular indentation within which a plurality of apertures is located; Figure 3B is an end view of the pipe of Figure 3A; Figure 3C is a bottom plan view of the pipe of Figure 3A;

Figure 4A is a perspective view of a fourth embodiment of a gas distributor according to the invention which comprises a pipe with a plurality of longitudinally arranged rectangular indentations within each of which an aperture is located; Figure 4B is an end view of the pipe of Figure 4A; Figure 4C is a bottom plan view of the pipe of Figure 4A;

Figure 5A is a perspective view of a fifth embodiment of a gas distributor according to the invention which comprises a pipe with a continuous longitudinal V-shaped indentation within which a plurality of apertures is located; Figure 5B is an end view of the pipe of Figure 5A; Figure 5C is a bottom plan view of the pipe of Figure 5A;

Figure 6A is a perspective view of a sixth embodiment of a gas distributor according to the invention which comprises a pipe, shown upside down for the sake of clarity, with a plurality of longitudinally arranged indentations of different shapes within each of which an aperture is located; Figure 6B is and end view of the pipe of Figure 6A, also shown upside down; Figure 6C is a bottom plan view of the pipe of Figure 6A; Figure 7A is a perspective view of the gas distributor pipe of Figure 1 A, shown upside down for the sake of clarity, with a cover over the continuous longitudinal indentation;

Figure 7B is an end view of the pipe of Figure 7A, also shown upside down; Figure 7C is a bottom plan view of the pipe of Figure 7A;

Figure 8 is a sectional end view of an eight embodiment of a gas distributor according to the invention which comprises a pipe with, the view taken through an endless circumferential indentation in which the two apertures have been placed in the dry shadow of the pipe; Figure 9 is a side view of the pipe in Figure 8, showing one row of apertures extending along the length of the pipe; and Figure 10 is a sectional side view of a stacked particle bioreactor which includes a gas distributor according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have determined that there are three key requirements of an improved gas distributor, namely:

• Protection for the apertures from blocking by random alignment of carbonaceous material, which may occur during stacking of the bioreactor after placement of the pipe;

• Protection for the apertures from precipitates forming in them as a result of evaporation of liquid draining through the stack which runs over the apertures or over material proximate the apertures; and • The gas distributor should preferably comprise a single piece.

These requirements are achieved at least partly in the invention of which several embodiments are described by way of example only.

Figures 1 A to 1 C presents a preferred embodiment of the invention. A pipe (1 ) with a continuous semi-circular indentation (2) formed along the length of the pipe (1 ) is used for the gas distributor. Apertures (3) are drilled through the pipe wall in the indentation (2). The pipe (1 ) is laid with the apertures (3) facing downwards in the stack.

The apertures (3) are protected from blockage by adjacent material since it is placed onto the material, and additional material stacked onto the pipe will not be located adjacent the apertures (3). The apertures (3) are located inside the indentation (2) which creates a space between the apertures (3) and the material on which the pipe (1 ) is laid.

The apertures (3) are protected from liquid running over them by having them located underneath the pipe (1 ) and spaced from the bottom (4) of the pipe (1 ). The indentation (2) provides an exit path along the entire length of the pipe (1 ) for gas introduced through it, as opposed to only in the immediate vicinity of the apertures (3).

Since the pipe is of a single length it is simply laid with the apertures (3) face down onto a layer of material and can then be covered with more material, which is simpler, quicker and cheaper than prior art gas distributor systems.

Figures 2A to 2C show an alternative embodiment of the invention. In this embodiment a plurality of indentations (5) are formed in the pipe (6) and an aperture (7) is drilled through the pipe wall inside each indentation (5). The indentations (5) are spaced apart by a predetermined distance. Although the exit path for gas is less than for the preferred embodiment shown in Figures 1 A to 1 C, it is still greater than just the immediate vicinity of the aperture. The apertures (7) are also protected from blockage by material and precipitates and the pipe (6) is made from a single piece of material.

For pipes which have a relative thick wall the indentation may be cut from the pipe wall itself. Two embodiment of gas distributors which includes such indentations are shown in Figures 3A to 3C and 4A to 4C. In the pipes shown in these Figures, a rectangular indentation is cut from the pipe wall. In Fig 3A to 3C a continuous indentation (8) is cut from the pipe wall (9) and in Fig 4A to 4C a series of rectangular indentations (10) are cut from the pipe wall (1 1 ).

The indentation, whether continuous or periodic, may take any size and form that adequately protects the apertures from blockage by material and precipitates. Non-exhaustive examples include V-shaped (12) or U-shaped indentations as shown in Figures 5A to 5C. Further examples of periodic indentations include circular (13), star (14), triangular (15), pentagonal (16), and square (17) shapes, as shown in Figures 6A to 6C.

The indentation may be covered by a shield (18) to protect further the apertures (19) against blockage, especially when the pipe (20) is intended to be placed in a layer of relatively fine material. The shield (18), as shown in Figures 7A to 7C, comprise a perforated mesh (21 ) which is secured over the indentation (22), in this case, or in the case of a series of indentations as shown in Figure 2A to 2C a complimentary number of shields would be secured over the indentations. The pipe (20) is shown with the apertures facing upwards in Figures 7A and 7B. This is for the sake of clarity only and this pipe (20) will be installed with the apertures (19) facing downwards in the stack, similar to the other embodiments described above.

Figure 8 shows an end view of a purge pipe (23) with apertures (24) located in the dry shadow (25) of the pipe (23). As mentioned above, the size of the dry shadow (25) depends amongst other things on the diameter of the pipe (23), the hydraulic conductivity of the material within which the pipe is located, and the amount of liquid (26) passed through the stack. For given conditions in a stack there is a dry shadow (25). The size of the dry shadow (25) may vary with variations in the conditions of the heap, which means there may be areas at the boundary (27) of the dry shadow that do see solution from time to time. To keep the purge pipe (23) from flooding with liquid (26) through the apertures (24), the apertures (24) are located in the actual dry shadow (25) and not, for example, in the boundary zone (27). Figure 9 shows a side view of the pipe of Figure 8, in which the spaced apart circumferential indentations (28) or grooves are also shown.

Figure 10 shows a stacked particle bioreactor (30). The stacked particle bioreactor (30) includes a stack (31 ) of carbonaceous material, which is biologically treated to produce synfuels. The stack (31 ) is, in this embodiment, covered by means of a sheet (32) to ensure anaerobic conditions in the stack (31 ). Proximate the top surface of the stack (31 ) there is buried a network of irrigation emitters (33) which deliver irrigation solution to the stack (31 ) when required.

Located underneath the emitters (33) is a network of gas collectors (34) which collect the gas which rise through the stack (31 ). The collected gas is piped from the stack (31 ) for further processing or recycling.

At the bottom of the stack (31 ), buried in the drainage layer (35), is a series of perforated pipes (36) which form a drain. Liquid synfuel, which is produced in the stack (31 ), drains through the stack (31 ) to the drainage layer (36) where it is collected by the perforated pipes (36) and piped from the stack (31 ) for processing or recycling.

The construction of the stack (31 ) so far is similar to the constructions of stacked particle bioreactor as described in patent application US2006/0223154A1 . The stack (31 ) also includes a network of gas distributors (37) according to the invention, which is buried in the stack (31 ) underneath the gas collector (34) and above the drainage layer (35). Each gas distributor (38) comprises a perforated pipe (39) as described above which extends through the stack (31 ). Gas, which may take the form of purge gas or air, is pumped, or in the case of air may also be allowed under atmospheric pressure, into the gas distributors (38). The gas exits the pipes (39) at their spaced apart perforations and is thereby distributed throughout the stack (31 ). The perforations on each pipe (39) are preferably equidistantly spaced apart. Also, the individual pipes (39) in the network of pipes are also preferably equidistantly spaced apart in the network of pipes. This ensures a matrix of evenly spaced perforations which evenly spreads the gas delivery through the stack (31 ).

The location of the apertures in the bottom of each pipe (39) and in particular in the dry shadow of each pipe (39) ensures that liquid such as liquid synfuel draining through the stack (31 ) does not come into contact with the apertures which minimizes precipitation in or around the apertures. This reduces or minimizes the problems identified above.

It will be appreciated that the embodiments described above have been include by way of example only, and are not intended to limit the scope of the invention. It is possible to alter certain aspects of the embodiments within the scope of the invention.

It is for example possible for an aperture to face downwards even when it is angled at about just less than 45° from the vertical. If it was at 45° or more it would be angled sideways. It is possible to use a pipe with a single row of apertures which face downwards at an angle just less than 45° from the vertical.

Claims

1 . A gas distributor for a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material comprising a pipe having a series of apertures through the wall of the pipe, and with at least one aperture located in an indentation in the outer wall of the pipe.

2. A gas distributor for a stacked particle bioreactor which produces synfuels from biodegradable carbonaceous material comprising a pipe having a series of apertures through the wall of the pipe, with the series of apertures configured operatively to face downwards in a stacked particle bioreactor.

3. A gas distributor as claimed in claim 1 or 2 in which the pipe includes at least one continuous indentation.

4. A gas distributor as claimed in claim 3 in which the continuous indentation extends longitudinally along the outer wall of the pipe and at least one of the apertures is located within the continuous indentation.

5. A gas distributor as claimed in claim 3 in which the continuous indentation comprises an endless circumferential indentation and at least one of the apertures is located within the circumferential indentation.

6. A gas distributor as claimed in claim 5 in which the pipe includes a plurality of endless circumferential indentations.

7. A gas distributor as claimed in claim 5 or 6 in which each endless circumferential indentation includes two apertures spaced apart by between about 0° and 45° degrees from the vertical along the circumference of the pipe.

8. A gas distributor as claimed in any one of claims 2 to 7 in which the series of apertures extends longitudinally along the pipe in a line which is orientated between about 0° and 45° degrees from the vertical along the circumference of the pipe.

9. A gas distributor as claimed in claim 3 in which the continuous indentation comprises a helical indentation, and for a plurality of apertures to be located in the circumferential indentation.

10. A gas distributor as claimed in claims 1 to 4 which includes a perforated cover over each aperture.

11 . A gas distributor as claimed in claims 1 to 4 which includes a single perforated cover over the continuous indentation.

12. A gas distributor as claimed in claims 5 to 7 which includes a perforated cover over each aperture.

13. A gas distributor as claimed in claims 5 to 7 which includes a single perforated cover over each endless circumferential continuous indentation.

14. A gas distributor as claimed in claims 5 to 7 which includes a single perforated cover over all the endless circumferential continuous indentations.

15. A gas distributor as claimed in claim 8 which includes a perforated cover over each aperture.

16. A gas distributor as claimed in claim 8 which includes a single perforated cover over each the helical indentation.

17. A gas distributor as claimed in any one of claims 1 read with any of claims 3 to 16 in which the series of apertures are configured operatively to face downwards in a stacked particle bioreactor.

18. A gas distributor as claimed in any one of claims 1 to 17 in which the apertures are configured operatively to be located in the dry shadow of a stacked particle bioreactor.

19. A stacked particle bioreactor which produces synfuels from carbonaceous material which includes a gas distributor as claimed in any one of claims 1 to 18.

20. A method of forming a stacked particle bioreactor which includes installing a gas distributor as claimed in any one of claims 1 to 18 in the stacked particle bioreactor.

21 . A method of producing gaseous fuel from biodegradable carbonaceous material using a stacked particle bioreactor which includes the step of introducing gas into the stacked particle bioreactor through a gas distributor as claimed in any one of claims 1 to 18.