WO2016107868A1

WO2016107868A1 - Thermal reactor

Info

Publication number: WO2016107868A1
Application number: PCT/EP2015/081344
Authority: WO
Inventors: Gunnar Sanner
Original assignee: Gunnar Sanner
Priority date: 2014-12-30
Filing date: 2015-12-29
Publication date: 2016-07-07

Abstract

The present invention provides a thermal driven reactor comprising a reaction chamber tolerating to be heated above 500°C and tolerating an internal pressure of above 50 atm, wherein the reaction chamber comprises walls and at least part of said walls are configured to transfer heat energy into the reaction chamber, a reactant inlet in fluid communication with the reaction chamber and at least one sorber element movable between a position within the reaction chamber and a position in a desorption chamber in communication with the reaction chamber, and the fluid communication with the reaction chamber is closable so that the desorption chamber can be depressurized without influencing the pressure in the reaction chamber, and at least one reaction product conduit in fluid communication with the desorption chamber via a closable reaction product outlet, and a method for performing thermal reaction.

Description

Thermal reactor

The present invention relates to a thermal reactor for performing water splitting or reacting water, nitrogen or C0₂ to hydrogen, ammonia or hydrocarbons, and to a method for preforming the reactions with limited temperature and pressure changes within the reaction chamber.

Background

Three megatrends characterize the energy situation of the world. Firstly, the global energy consumption grows due to economic development of dense populated areas of the world (Asia, Africa and South-America). Secondly, we are running out of easily available hydrocarbon fuel like oil and gas. Thirdly, accelerated use of fossil fuel is emitting large amounts of carbon dioxide (C0₂) to our atmosphere possibly causing global warming and increased ecological instability. These megatrends, put together, represent a challenge for our civilization. Policy- and decision makers: politicians, scientists and leaders in corporations struggle to find a sustainable way further.

Proposed ways forward is to utilize nuclear reactor heat or solar heat to split water into hydrogen and oxygen, alternatively combined with nitrogen to produce ammonia, alternatively combined with C0₂ to produce hydrocarbons. Resulting products of the reactions (H₂+0₂ or NH₃ + 0₂ or (hydrocarbons+0₂) could be stored, transported and used for all type of energy usage (e.g.: direct combustion for heat production, combustion engines for transport purposes or gas turbines or fuel cells for power production). When hydrogen/ammonia and oxygen are recombined energy is emitted without emission of C0₂. When resulting hydrocarbons and oxygen are recombined energy is emitted with C0₂ neutral emission. If the resulting products are recycled to new cycles, we will have a closed loop energy system usable both on earth and on planets without oxygen in their atmosphere (ref. :

Sanner cycle energy system - WO 2012/069635 A2). When used on earth, it could be sufficient to store and transport the hydrogen/ammonia only, since at time of combustion, oxygen can be taken from the air. The three main steps in a renewable hydrogen/ammonia/hydrocarbon value chain are: 1) Produce/gather heat, 2) Use the heat for the endothermic reactions, and 3) Transport resulting hydrogen/ ammonia/hydrocarbons to energy consumers.

• The first step is well demonstrated in both nuclear plants and concentrating solar thermal plant. · The third step, "Large-Scale Hydrogen Storage and Transportation System", is recently (2013) demonstrated (ref. : Method for producing hydrogen aimed at storage and transportation - US20120321549). Hydrogen is fixed to toluene producing methyl-cyclo-hexane (MCH); which is liquid phase at ambient temperature and pressure. This system can utilize existing

infrastructures, including oil tanks and tankers for storage and transportation, without the need for cryogenic technologies such as is used for LNG and liquefied hydrogen. Ammonia can be transported on standard LPG tankers.

• The remaining challenge for a renewable hydro gen/ammonia value chain is the second step: Thermal reaction to produce Hydrogen or Ammonia.

Prior art US2013/0266502 discloses a number of reaction designs for production of hydrogen and oxygen by gas-phase reduction/oxidation reactions at isothermal conditions. The energy may be supplied as concentrates solar energy. The reactions are performed by providing two reactors run in opposite modes generation and regeneration and alternating which of the processes is performed in the reactors. US4332775 discloses a rotary tubular reactor for dissociation of water.

US2009/0232716 discloses a reactor for the production of hydrogen using selective membranes. GB1532403 also discloses a device for hydrogen generation

comprising selective membranes.

US4,873,061 discloses a solar reactor for nitrogen fixation.

Objectives of the invention

The objective of the present invention is to provide equipment and a method for thermally splitting water or react water and nitrogen to ammonia or react water and C0₂ to syngas, or hydrocarbons such as alkanes or alcohols, wherein the equipment allows for relative constant temperature and pressures within the reaction chamber.

A further objective is to provide equipment that allows for continuously operation.

It is also an objective of the present invention to provide equipment and a method that avoids and/or limits the need for sweep gas and results in a purer gas product.

This invention is based on the principles of "reversed combustion". This is a process to convert e.g.: combinations of Biomass (or natural gas (NG), coal, oil), H₂0, C0₂, N₂, H₂ and air to gaseous or liquid hydrocarbons or other fuels like H₂ and NH₃. The process is driven by Renewable energy (RE) or Nuclear Energy (NE) fed to the process directly or indirectly, e.g. : through heat from CSP/Nuclear plant, through heat from a medium that has absorbed heat from RE/NE (e.g.: molten salt), or electrical heater driven by RE/NE power. The main principle behind the invention is that reactants are fed into a chamber, the reversed combustion takes place in the chamber under high pressure and high temperature, and the products are taken out of the chamber by sorption (adsorption or absorption) by elements put into and taken out of the chamber without changing the pressure and temperature in the chamber significantly, by filter or by tapping out liquids (if possible).

To solve these and other objectives the present invention provides a thermal driven reactor comprising a reaction chamber tolerating to be heated above 500°C and tolerating an internal pressure of above 50 atm, wherein the reaction chamber comprises walls and at least part of said walls are configured to transfer heat energy into the reaction chamber, a reactant inlet in fluid communication with the reaction chamber and at least one sorber element movable between a position within the reaction chamber and a position in a desorption chamber in communication with the reaction chamber, and the communication with the reaction chamber is closable so that the desorption chamber can be depressurized without influencing the pressure in the reaction chamber, and at least one reaction product conduit in fluid communication with the desorption chamber via a closable reaction product outlet. Applicable sorber materials for the sorber element are any absorber material with an ability to selectively absorb oxygen, or hydrogen or ammonia or C0₂ or alkanes or alcohols or other hydrocarbons at the reactor conditions and any adsorber materials with an ability to selectively adsorb oxygen or hydrogen or ammonia or C0₂ or alkanes or alcohols or other hydrocarbons at the reactor conditions. Examples of such absorber materials include but are not limited to materials disclosed in

US4521398; Solar Energy 2005, Agrafiotis et al, "Solar water splitting for hydrogen production with monolithic reactors"; US6660066; and US2012/0276254. Examples of such adsorber materials include but are not limited to adsorber materials disclosed in US571 1926, CN103864104, US4266957, EP0846745, US7431 151 , US201 1/0306488 In one aspect of the thermal driven reactor according to the present invention the reactions chamber tolerates an internal pressure of 700 atm. In a further aspect the reactions chamber tolerates an internal temperature of 2000-3000°C.

In another aspect of the thermal driven reactor the at least one sorber element sorbs oxygen at high pressure and releases sorbed oxygen at low pressure in the desorption chamber.

In a further aspect the reactor comprises at least two sorber elements adapted to sorb to different reaction products and release these to two separate reaction product conduits. In another aspect the thermal driven reactor further comprises a hydrogen filter arranged within the reaction chamber and comprising a hydrogen outlet arranged outside the reaction chamber, wherein the hydrogen outlet is in fluid communication with a hydrogen conduit.

In yet another aspect of the present invention the reactant is water and optionally nitrogen or air and the reaction products are oxygen and hydrogen or ammonia.

In yet another aspect of the present invention the reactant is water and C0₂ and the reaction products are oxygen and syngas (hydrogen + CO) or alkane or alcohol.

The reactor may in a further aspect comprise an outlet for a liquid reaction product where the outlet is in fluid communication with the reaction chamber through a valve element allowing for controlled removal of liquid reaction formed within the reaction chamber.

The present invention further provides a method of performing a thermal reaction, wherein the method comprises providing a thermal driven reactor according to the present invention, supplying heat to at least part of the walls of the reaction chamber, thereby heating the chamber to above 500°C,

supplying a reactant to the reaction chamber, wherein the reactant is water and optionally nitrogen or air, sorbing at least a first reaction product in the at least one sorber element arranged in the reaction chamber, transferring said at least one sorber element to the at least one desorption chamber, desorbing the first reaction product from said at least one sorber element and supplying the first reaction product to the reaction product conduit. In one aspect of the method the thermal driven reactor comprises a second sorber element for sorbing a second reaction product, the method comprises transferring said second sorber element to a second desorption chamber, desorbing the second reaction product from said second sorber element and supplying the second reaction product to a second reaction product conduit.

In a further aspect the reactant is water and optionally nitrogen or air or C0₂.

In yet another aspect the first reaction product is oxygen.

In another aspect the second reaction product is hydrogen or ammonia or syngas or alkane or alcohol. In yet another aspect of the method the pressure within the reaction chamber is kept above 50 atm during the method and the pressure with in the one or more desorption chambers are below 50 atm during the desorption steps.

The term "filter" as used here in connection with hydrogen, oxygen, ammonia, CO, syngas, alkanes or alcohols refers to a structure which selectively allows for the penetration of one of these gasses there through. Accordingly the filter functions as a selective membrane where hydrogen, oxygen, ammonia CO, syngas, alkanes or alcohols passes though the filter and is transported out of the reaction chamber. The filter is made of a material that can sustain the high temperature within the reaction chamber, the filter may for instances be a ceramic membrane. The filter can have any suitable shape; preferably the shape is adapted to provide the membrane surface with as large a filter surface as possible.

Brief description of the drawings

The present invention will be described in further detail with reference to the enclosed drawings.

Figure 1 schematically illustrates a cross sectional view of a first embodiment of a thermal driven hydrogen/ammonia reactor.

Figure 2 illustrates a cross sectional view along the line A-A of the first

embodiment of the thermal driven hydrogen/ammonia reactor.

Figure 3 schematically illustrates a second embodiment of the thermal driven hydrogen/ammonia reactor.

Figure 4 schematically illustrates a cross sectional view of a third embodiment of the thermal driven hydrogen/ ammonia reactor. Figure 5 schematically illustrates a cross sectional view along the line B-B of the third embodiment of a thermal driven hydrogen/ammonia reactor, but with an alternative internal configuration.

Description

A solution provided by the present invention, illustrated on figure 1 , is a thermal driven water reactor 1 that is capable of running the reaction 2H₂0 => 2H₂ + 0₂ at high temperatures, e.g. 2000-3000 °C, and high pressure, e.g. 700 atm. The solution sorts the reaction products at this high temperature through absorption optionally combined with selective filter mechanisms. Applicable combinations of temperature and pressure condition in the reaction chamber are above 500°C and above 50 atm, or a temperature between 500-3000°C and a pressure between 50-1000 atm, or a temperature between 1000-2500°C and a pressure above 100 atm, or a temperature between 1500-2000°C and a pressure above 300 atm.

The main part of the solution is a reaction chamber 5 that is capable of receiving heat 30 from e.g. nuclear reactions or solar fields.

The heat input can take place through the outer walls 3 when cooling media from nuclear reaction heat transfer towards the reaction chambers outer wall 3, or concentrated solar beams are mirrored towards the reaction chambers outer wall 3. In the solar case, the reaction chamber 5 is the central receiver up in the tower of a concentrated solar thermal park. Alternatively, heat can be lead more directly into the reaction chamber so the cooling media from nuclear reaction heat transfer more directly with the chemical substances taking part in the reaction in the reaction chamber, or solar beams are led into the chamber via transparent walls 3 or part of the walls 3.

Connected to the reaction chamber there is a special construction with at least three pipes covered in an outer layer of thermic insulation 9 to limit leakage of energy as heat out of the system. Trough the inner, central supply pipe 2 water and optionally nitrogen or air is supplied to the reaction chamber 5. The two pipes 12 and 12' are arranged to transport the respective reaction products out of the system. The thermal splitter comprises at least two but preferably at least four selective absorber elements 13, 13 ' . These absorber elements are adapted to when arranged within the reaction chamber 5 to selectively absorbed one of the reaction products. In the case of water splitting at least one absorber element selectively absorbs oxygen and at least one absorber element selectively absorbs hydrogen. All the absorber elements 13, 13 'are arranged on a separate positioning element 20, 20' and the positioning element allows for the absorber elements to be controllable position respectively inside the reaction chamber 5 and inside a desorption chamber 17, 17' . In figure 1 the absorber element 13 is arranged in the reaction chamber 5 and the free end thereof comprises a closing element 15 which is not in contact with the opening 6 between the reaction chamber 5 and the desorption chamber 17. The opening between the desorption chamber 17 and the pipe 12 is blocked by blocking element 19. The blocking element can be removed and reintroduced reversibly to so that when the closing element 15, 15 ' seals the opening 6 the blocking element is removed, and when the desorption is completed the blocking element 19 is reintroduced before the absorber element 13 reenters the reaction chamber.

The positioning elements 20, 20' can be moved from the retracted to the extended position and back again by different mechanisms, such as hydraulic or magnetic lifting methods well known in the art.

The surface 1 1 of the absorber element 13 may contain catalytic active compounds improving the efficiency of the reaction and/or a membrane improving the selectivity of the absorption. The other illustrated absorber element 13 ' is arranged inside the desorption chamber 17' . The closing element 15 ' arranged at the free end of the absorber element is in sealing contact with the opening between the reaction chamber 5 and the desorption chamber 17'. The desorption chamber 17' is in fluid communication with the product pipe 12' . The positioning elements 20, 20' allows for the absorber elements to be freely moved between the two positions illustrated and thereby between the two chambers. When arranged in the reaction chamber the absorber element 17 absorbs selectively one of the gases generated by the reaction. When retracted to the desorption chamber the desorption chamber is sealed of from the reaction chamber so that the high pressure within the reaction chamber 5 is maintain at a constant level whereas the pressure within the desorption chamber 17' is allowed to be reduced by the opening of the pipe 12' and thereby the absorbed gas is released due to the reduced pressure. The thermal driven hydrogen/ammonia reactor preferably contains several absorber elements for selectively absorbing each of the gas products produced by the reaction, thereby at least one absorber element for each gas product can be active within the reaction chamber while at least one absorber element for each gas product is arranged in its respective desorption chamber for release of the produced gas element and regeneration of is absorption capabilities. The pressure within the desorption chamber during the desorption process is in one embodiment below the pressure in the reaction chamber. The pressure is at least 1 atm below the pressure in the reaction chamber. The pressure in the desorption pressure is between 1 atm and 20 atm.

Alternatively the absorbers can be regenerated at higher or lower temperature and/or at lower pressure than within the reaction chamber, optionally combined with the use of inert gases to ventilate out the produced gas. The inert gas is separated from the produced gas in a down stream separation process. Water and optionally nitrogen or air is pumped into the reaction chamber 5 by a pump located upstream of the supply pipe 2. Water is preferably in its liquid phase, so that the pumping is energy efficient. The pump is preferably water cooled with water being pumped into the reactor, this limits energy leakage. The pump will, while in operation, keep constant pressure. A pressure sensor giving signal to and monitoring of the pump can be included in a control and management system. The pump can be two-ways, so that if the pressure is increase above limits, it will pump water out.

When water reaches the reactor chamber it will vaporize due to the heat. The reaction chamber will be filled with hot vapor increasing temperature until the equilibrium 2H₂0(1) <=> 2H₂(g) + 0₂(g), ΔΗ = 571.6 kJ/mole, is pushed somewhat to the right. Without evacuating and/or absorbing hydrogen and oxygen, not much of the water vapor will react. In the solution according to the present invention wherein the reaction chamber comprises both at least one hydrogen absorber element and at least one oxygen absorber element, the absorption of the elements on the right side of the equation will drive the reaction to the right.

As long as the oxygen and hydrogen absorbers are not filled with oxygen or hydrogen respectively, the process will continue to go. But when the absorbers cannot take up any more, they are retracted into the desorption chambers wherein the absorbed gases are released.

For both the export of hydrogen and oxygen there might be a collecting point for rest-water that is fed back into the water input pipe. These collecting points will be located downstream in the pipes 12, where the temperature has fallen below 100 °C, and water is condensed to liquid phase. The shape of the reaction chamber and the absorber elements can be freely selected and can be cylindrical or other spherical shapes.

Figure 2 illustrates a cross sectional view a long the line A-A in figure 1 of thermal splitter according to the present invention. In this cross-sectional view twelve absorber elements 13 are visible. In one embodiment all absorber elements are adapted to selectively absorb one of the two reaction products from the reaction. In this embodiment the other reaction product has to be removed directly from the reaction chamber 5, by providing an outlet and a conduit from the outlet to a separation unit wherein the reaction product is separated from unreacted supplied gas (water and optionally nitrogen or air). Figure 3 illustrates a cross sectional view through a thermal reactor according to an embodiment of the present invention wherein two types of absorber elements 1 13 and 1 14 are distributed with in the reaction chamber 5. Each type of absorber element respectively selectively absorbs one of the reaction products. Each of the absorber elements is regenerated and the separated reaction product released as described in connection with figure 1.

In the embodiment illustrated on figure 3 when water is split the absorber elements 1 13 and 1 14 are respectively hydrogen and oxygen absorbers. The number of absorbers used for hydrogen and oxygen will be decided based on their ability to absorb the product gases.

The alternative reaction involving nitrogen gas splitting as well as water splitting and ammonia formation involves the reaction: 2N₂(g) + 6H₂0(1) <=> 4NH₃(g) + 30₂(g), ΔΗ = 1530 kJ/mole

If Nitrogen gas is fed into the reactor chamber in addition to water, the reactor will produce ammonia and oxygen. Ammonia and oxygen can then be extracted from the reactor chamber by use of described absorber principles. The nitrogen needed as input will be extracted from the air by use of an air separation unit. Alternatively to pure nitrogen, air can be fed into the reactor chamber in addition to water, since air consists of 78.084 mole % nitrogen.

Air (2N₂(g) + 0.561 0₂*(g)) + 6H₂0(1) <=> 4NH₃(g) + 3.561 0₂(g)

*) 0₂ and other gases in air that are not Nitrogen. Air consist of 78.084 % nitrogen

The oxygen (20.947 mole %) that is part of the air, will be extracted from the reactor chamber together with oxygen produced in the reaction. Small volumes of other gases in air (~1 mole %) can be ventilated out of the reaction chamber after a period of running.

Figure 4 illustrates an alternative embodiment of a thermal driven

hydrogen/ammonia reactor. Compared to the embodiment illustrated on figure 1 the embodiment on figure 4 comprises a selective filter element 216 through which a first of the two reaction products are removed from the reaction chamber. The absorber elements 213 and 213 ' are designed to selectively absorb the second reaction product, and reversibly release the second reaction product in the desorption chamber 17' . The filter 216 within the reaction chamber is in one embodiment thereof a hydrogen filter chamber with walls capable of filtering out H₂ molecules and persist the high pressure in the reaction chamber. The pressure inside the hydrogen filter will be kept low at all time of operation, e.g. in the range from 0.1 to 1 atm. The hydrogen filter in one embodiment has a construction and shape that maximizes the surface area for filtering purposes. Within the reaction chamber there is one, or preferably several, oxygen absorbers 213 capable of absorbing large amount of oxygen gas under high pressure. When the absorbers are retracted into the desorption chambers the pressure is released, and the oxygen is freed from the oxygen absorber. The hydrogen streams out automatically at above 1 atm., or is pumped out at down to 0.1 atm. (to increase speed of the water splitting). The hydrogen is continuous evacuated so the pressure inside the hydrogen filter is kept on the same low level at all time.

At the stage where the oxygen absorbers are removed from the reaction chamber (lowered into chambers below), while another set of oxygen absorbers are lifted up into the reaction chamber (from chambers below). This exchange of oxygen absorbers takes place at constant temperature and pressure in the reaction chamber.

Technically the change of oxygen absorbers takes place when the valves or blocking plate for oxygen export are closed in the bottom of the filled desorption chambers, another valves for high pressure vapor is opened, so those desorption chambers containing absorber elements to be return into the reaction chamber get the same pressure as the reaction chamber. At that point doors between the desorption chamber and the reaction chamber can be opened and the new oxygen absorbers can be lifted up. On the other hand, filled oxygen absorbers are lowered down in the empty desorption chambers. Doors are closed between these chambers and the reaction chamber and oxygen export valves/blocking plates are opened so mainly oxygen can stream out as the pressure is lowered and/or temperature is changed and/or inert gas is added. The replacement process of oxygen absorbers can either happen by changing half of the absorbers in one round or sequentially one and one to get a smoother operation.

The advantage with this solution is that the water splitting process runs continuous because the temperature and the pressure is kept constant in the reaction chamber and there will always be oxygen absorbers with remaining capacity to absorb oxygen in the chamber.

The main principals of the present invention may be employed in the production of alkanes, alcohols and other liquid hydro carbons. The total reaction schemes for alkanes is

(n) C0₂ + (n+1) H₂0 => C„H_2n+2 + (3n+l)/2 0₂,

wherein n=alkane number

The total reaction schemes for alcohols is (n) C0₂ + (n+1) H₂0 => C_nH_2n+1 OH + (3/2)n 0₂, wherein n=alcohol number.

Claims

Thermal driven reactor comprising

- a reaction chamber tolerating to be heated above 500°C and tolerating an internal pressure of above 50 atm, wherein the reaction chamber comprises walls and at least part of said walls are configured to transfer heat energy into the reaction chamber,

- a reactant inlet in fluid communication with the reaction chamber and

- at least one sorber element movable between a position within the reaction chamber and a position in a desorption chamber in communication with the reaction chamber, and the communication with the reaction chamber is closable so that the desorption chamber can be depressurized without influencing the pressure in the reaction chamber, and

- at least one reaction product conduit in fluid communication with the desorption chamber via a closable reaction product outlet.

Thermal driven reactor according to claim 1 , wherein the reactions chamber tolerates an internal pressure of 700 atm.

Thermal driven reactor according to claim 1 or 2, wherein the reactions chamber tolerates an internal temperature of 2000-3000°C.

Thermal driven reactor according to any one of the claims 1-3, wherein the at least one sorber element absorbs and or adsorbs oxygen at high pressure and releases absorbed and or adsorbed oxygen at low pressure in the desorption chamber.

Thermal driven reactor according to any one of the claims 1-4, wherein the reactor comprises at least two sorber elements adapted to absorb and/or adsorb two different reaction products and release these to two separate reaction product conduits.

Thermal driven reactor according to any one of the claims 1-4, wherein thermal driven reactor is a hydrogen reactor and further comprises a hydrogen filter arranged within the reaction chamber and comprising a hydrogen outlet arranged outside the reaction chamber, wherein the hydrogen outlet is in fluid communication with a hydrogen conduit.

7. Thermal driven reactor according to any one of the proceeding claims, wherein the reactant is water and optionally nitrogen, C0₂ or air and the reaction products are oxygen and hydrogen or ammonia or syngas or alkane or alcohols.

8. Method of performing a thermal reaction, wherein the method comprises

- providing a thermal driven reactor according to any one of the claims 1-7,

- supplying heat to at least part of the walls of the reaction chamber, thereby heating the chamber to above 500°C,

- supplying a reactant to the reaction chamber, ,

- sorbing at least one reaction product in the at least one sorber

element arranged in the reaction chamber,

- transferring said at least one sorber element to the at least one desorption chamber,

- desorbing the at least one reaction product from said at least one

sorber element and supplying the reaction product to the reaction product conduit.

9. Method according to claim 8, wherein the thermal driven reactor comprises a second sorber element for sorbing a second reaction product , the method comprises

- transferring said second sorber element to a second desorption chamber,

- desorbing the second reaction product from said second sorber

element and supplying the second reaction product to a second reaction product conduit.

10. Method according to claim 8 or 9, wherein the reactant is water and optionally nitrogen or air or C0₂.

1 1. Method according to claim 8 or 9 or 10, wherein the first reaction product is oxygen.

12. Method according to claim 9 or 10 or 1 1 , wherein the second reaction product is hydrogen or ammonia or syngas or alkane or alcohol.

13. Method according to any one of the claims 8 to 12 wherein the pressure within the reaction chamber is kept above 50 atm during the method and the pressure with in the one or more desorption chambers are below 50 atm during the desorption steps.