GB2158817A

GB2158817A - Manufacture of ammonia and related products and methods of and means for producing power and cooling

Info

Publication number: GB2158817A
Application number: GB08510630A
Authority: GB
Inventors: Amnon Yogev
Original assignee: Ormat Turbines Ltd
Current assignee: Ormat Industries Ltd
Priority date: 1984-04-27
Filing date: 1985-04-26
Publication date: 1985-11-20
Also published as: GB2190912B; IL75022A; GB8717230D0; FR2564138B1; MX171199B; JPS6183622A; DE3515197A1; IL75022A0; GB2190912A; GB2158817B; FR2564138A1; GB8510630D0

Abstract

In the manufacture of ammonia and related compounds, energy consumption is reduced by (i):- directing ammonia gas through one feed line, and carbon dioxide gas and steam through another feed line, into a closed reaction chamber to form solid ammonium carbonate, resulting in a reduced pressure in the chamber, which reduced pressure can be used to drive heat engines in the reactant feed lines; (ii) an alternative pathway is constructed along part of the potassium carbonate loop. Carbon dioxide gas and water vapour formed by the heating of the potassium bicarbonate flow through a heat engine and are cooled and recycled. The reactant gases may be liquefied and revaporised in the event of reactor shutdown, and heat-exchange means may provide at least a portion of the heat of vaporisation of the liquefied reactants. The heat-exchange means can thus produce a refrigerating fluid as a result of the vaporisation of the reactants.

Description

SPECIFICATION Manufacture of ammonia and related products and methods of and means for producing power and cooling This invention relates to a process and apparatus for producing power and cooling in the manufacture of ammonia and related products, such as ammonium carbonate and ammonium sulphate.

The large-scale manufacture of ammonia and its derivative compounds has been performed since the early twentieth century according to a process developed by HABER and others.

The original process, substantially unmodified to the present day, begins with a fuel source, such as coke from bituminous coal or lignite. This fuel is blasted to incandescence and steam is passed through the fuel bed, eventually yielding a mixture of carbon dioxide and hydrogen gases.

The carbon dioxide must be separated from the hydrogen before the synthesis of ammonia can take place.

This is accomplished by directing the gas mixture into a potassium carbonate/potassium bicarbonate loop.

The loop must be kept in constant operation, even when the rest of the ammonia plant is shut down. In the loop, the gaseous mixture of hydrogen and carbon dioxide is treated with cold potassium carbonate aqueous solution. This results in the production of an aqueous potassium bicarbonate solution. Free hydrogen gas is removed and the potassium bicarbonate solution is then heated to approximately 130"C to regenerate potassium carbonate by evolving carbon dioxide and water vapour. The carbon dioxide and water vapour are vented to the atmosphere. The hot potassium carbonate solution is cooled by means of a heat exchanger, and the cooled solution is recycled. The separated hydrogen gas is combined with a suitable source of nitrogen such that the ratio of hydrogen to nitrogen is approximately 3:1.The hydrogen and nitrogen enter a synthesis loop where they pass over a catalyst in a high-pressure ammonia converter where the ammonia is formed.

Additional useful compounds can also be produced from the ammonia. For example, ammonium sulphate produced by treating the ammonia with sulphuric acid.

Should the potassium carbonate loop in the ammonia manufacture process have to be shut down because of trouble upstream or downstream of the loop, or because of lack of fuel or other material, considerable time and expense are involved in restoring the potassium carbonate cycle to normal operation.

Moreover, through ammonia and its chemical derivatives are very useful chemical compounds, a great deal of energy has to be expended in their manufacture. It would thus be desirable to provide a technique for reducing the energy needed to manufacture a given quantity of ammonia, as well as minimizing the amount of energy wasted when cycling the potassium carbonate loop when the rest of the system is shut down.

Generally speaking, the process of the invention is unique in that rather than relying upon the normal contraction which occurs when a gas is cooled to condense it, the present invention relies instead on chemical reaction kinetics to provide a final product which exerts a vacuum on its feedstreams. Thus, the invention is applicable to reactions wherein the temperature of the final product is not only lower than the reactants, as might be the case in a condensation phase change, but also in situations where the final product is at the same or even higher temperatures than the reactants. This principle forms one important aspect of the invention which will be described with reference to the accompanying drawing.

Although the drawing is a complete ammonia and ammonium sulphate production flow chart, the inventive process and apparatus include a number of distinct aspects which will be separately discussed below.

According to a first aspect of the invention, ammonium sulphate is formed by first reacting ammonia with carbon dioxide and water vapour in a reactor to form an ammonium carbonate solution (water vapour being provided in excess over the stoichiometric amount, so as to ensure that the resulting ammonium carbonate solution is a free flowing slurry), and subsequently reacting the ammonium carbonate solution with sulphuric acid to form ammonium sulphate. While it has been conventional to react ammonia directly with sulphuric acid to form ammonium sulphate in the prior art, it has now been found that by forming the ammonium carbonate intermediate, the process of ammonia manufacture can be manipulated, so that energy can be removed from the system.

Thus, if at least one of the reactants which form the ammonium carbonate is passed through a heat engine upstream of the reactor prior to being exhausted into a closed reactor, the formation of the solid ammonium carbonate (in solution) in the reactor creates a vacuum in the reactor resulting from the decrease in volume between the reactants and the products, which results in a pressure drop across the heat engine. The reaction chamber thus acts as a condenser for the exhaust of the heat engine which can be used to generate electricai power, for example.

The corresponding apparatus for the manufature of ammonium sulphate includes scources of ammonia, carbon dioxide and water vapour, as well as means for feeding the ammonia, carbon dioxide and water vapour into a reaction chamber wherein the ammonium carbonate is ultimately formed. A source of sulpuric acid is additionally provided and the apparatus includes means for reacting the ammonium carbonate with the sulphuric acid to form ammonium sulphate. Again, in the invented apparatus, a heat engine is connected between at least one of the reactant sources and the reaction chamber so as to take advantage of the pressure drop which occurs in the reaction chamber as the result of the formation of the ammonium carbonate.

According to another aspect of the invention, the potassium carbonate/bicarbonate loop which is conventionally used for separating the useful hydrogen out of flue gases in the manufacture of ammonia is modified so that the separated carbon dioxide and water vapour, which might otherwise be vented, are used to form ammonium carbonate. The advantage of this technique is that by saving and using the carbon dioxide in the system, the heat energy of the carbon dioxide, which is absorbed during heating of the potassium bicarbonate, can be at least partially recovered by passing the carbon dioxide through a heat engine prior to passage into the reaction chamber. Using this technique the pressure drop which occurs in the pressure chamber as a result of the formation of the ammonium carbonate results in a pressure drop across the heat engine which can drive the engine to recover energy.The ammonium carbonate which is formed may then be reacted with sulphuric acid to form ammonium sulphate. Quite obviously, a second heat engine may be positioned in the ammonia feed line to also take advantage of the reduced pressure in the reaction chamber.

In another aspect of the present invention, the reaction products of a process for the manufacture of ammonia and its by-products are thus used as working fluids in the production of power.

According to yet another aspect of the invention, when ammonium sulphate is not needed, such as when the material is in oversupply or when the available ammonia supply exceeds that needed for the manufacture of ammonium sulphate, the available ammonia supply may be reacted with a water vapour-carbon dioxide gaseous mixture to accumulate the ammonia in the form of ammonium carbonate, which may itself be stored. Again, energy may be generated by passing each of the streams through heat engines.

Alternatively, each of the gas streams may be pressure-liquefied, and stored in vessels at room temperature. When one desires to utilize the condensed liquids, the liquids can be simultaneously expanded through heat engines into an ammonium carbonate reaction chamber. In the process of gasification, the storage vessels are cooled, and can be used to cool a refrigerant flowing through a heat-exchange system in physical contact with the walls of the vessels. The gasification process can be controlled to occur isothermally. The energy of expansion can thus be considered to be the difference in free energy between the free energies of the reactants (i.e., water vapour, carbon dioxide, and ammonia) and that of the product, ammonium carbonate.

In yet another aspect of the invention, the Applicant has developed a technique for continuously operating the potassium carbonate/bicarbonate loop, and more specifically the retort heater used to heat the potassium bicarbonate solution continuously, even in the event of shutdown ahead of, or downstream of the loop. This is important, since in the event of system upset, e.g., in the event that the heaters and contact chambers of the loop are shut down, start-up is very costly and very time-consuming. Thus, the Applicant has found a technique in which, during upset, the loop is operated continuously be recycling the carbon dioxide and water vapour, which would normally have been vented upon leaving the potassium bicarbonate solution heater, and recovering the heat energy in this recycled stream, thus reducing the cost of operating the loop during this stand-by condition.Thus, according to the invention, the carbon dioxide gas, hydrogen gas and water vapour are first treated with a potassium carbonate solution to form potassium bicarbonate solution. Free hydrogen gas is separated from the potassium bicarbonate solution and the potassium bicarbonate solution is heated to regenerate potassium carbonate solution while liberating carbon dioxide and water vapour. The potassium carbonate solution is cooled in preparation for re-use and the liberated carbon dioxide and water vapour are cooled by passing the carbon dioxide and water vapour through a heat engine. The water vapour is provided in excess of the stoichiometric amount required in the reaction so that a free flowing slurry is formed and the heat engine blades do not become encrusted with material.The cooled carbon dioxide and water vapour are then treated with the cooled potassium carbonate solution and the process can be continued for as long as desired while nevertheless recovering energy which would otherwise be lost if the carbon dioxide stream were to be vented to the atmosphere.

In one of its broader aspects, the invention can be characterized as setting forth a process of forming a product in a reaction chamber from two or more reactants with the product having a lower pressure in the reaction chamber than the pressure of each of the reactants in the reactant feed lines. This results from the reduction in volume of the products of the reaction relative to the reactants. Thus, upon entering the reaction chamber the reactants react and a vacuum is generated within the reaction chamber which results in a pressure drop across at least one heat engine which is positioned in at least one of the reactant lines.It should be noted that, depending on the reactants used and the reaction conditions, it is possible to pass all of the reactants through a single line, such as when the reaction requires a catalyst, or to segregate the reactants with heat engines being positioned in some or all of the segregated reactant lines. The reaction chamber may be cooled by a heat exchanger (not shown) for the purpose of removing the heat which is formed in exothermic reactions within the reaction chamber.

According to this broad aspect of the invention, the reactants may be gasses with the reaction products being gaseious, solid, liquid or mixtures thereof. As described specifically with reference to the drawing, the reactans are ammonia, water vapour and carbon dioxide, with the reaction product being ammonium carbonate in solution.

At least four types of reactions may be contemplated for purposes of achieving the process of the invention relating to the generation of genergy by using a chemical reaction as a means for creating and/or increasing the pressure head of a system: (1) Reactions involving a gas and a liquid from separate sources: e.g., 2NH3 + H2SO4 (NH4)2S04 (2) Reactions involving different gasses which come from the same source (a closed loop system): e.g., H20 + CO2 + K2C03 > 2KHCO3;and (3) Reactions which involve different gasses which come from different sources, i.e., an open loop: e.g., 2NH3 + CO2 + H20 < (NH4)2C03 (4) Reactions which involve a gas and a solid:: e.g., CO2 + 2NaOH < Na2CO3 + H20 By way of example, the technique of the invention may be used to generate a vacuum which may in turn be used to drive a turbine in connection with the following reactions in closed loop cycles:

high pressure at 100"C at 200"C low pressure

The various compounds are heated until the occurrence of vaporization and decomposition into their components which are then expanded through a turbine, and reacted in a reaction chamber so as to reform the original compound.

The invention extends to the inventive apparatus which is used to form a product in a reaction chamber from at least two reactants, the product having a lower pressure in the reaction chamber than the inlet pressure of each of the reactants. In this embodiment, at least one line connects a source of each of the reactants to the reaction chamber and at least one heat engine is positioned in at least one of the lines whereby upon reaction of the reactants in the chamber a pressure drop occurs across the heat engine due to the reduced pressure in the reaction chamber.

As the product is formed in the reaction chamber, with the resultant lowering of pressure, the reactants are expanded through the feed lines into the reaction chamber. This expansion can occur under either isothermal or nonisothermal conditions. Any of the following three situations can exist: 1) Tin = T reaction chamber 2) Tin > T reaction chamber 3) Tin > T reaction chamber where Tin is the inlet temperature of the vapours (before expansion) and Treaction chamber iS the temperature of the reactor.

While continuous reference is made to the term"heat engine" throughout the application, it is to be understood that the term is used to include all manner of devices which can be used to extract the energy from the flowing reactants and may, for example, constitute a turbine which is connected to an electrical generator.

An embodiment of the invention is hereafter described in conjunction with the accompanying drawing which is a flow diagram of the process for the manufacture of ammonia and related compounds.

Referring now to the drawing the conventional process steps are shown in dashed lines, while the steps of the invention are illustrated in solid lines. The drawing shows a combustion source 10, such as a coke furnace, which provides a flue gas stream 12 of gaseous hydrogen and carbon dioxide. This stream is treated with an aqueous potassium carbonate solution stream 13 at a temperature of about 30"C in a gas-liquid treatment column 14. The potassium carbonate solution reacts with carbon dioxide in the stream to form potassium bicarbonate.The potassium bicarbonate solution 16 is then directed into a retort 18, where it is heated to approximately 1 30"C, thus regenerating the potassium carbonate solution 19, which is then cooled in a cooler 21 to a temperature of about 30"C. After being cooled, the potassium carbonate solution is recycled to the top of the treatment column 14, wherein it removes carbon dioxide from the input flue stream.

Along with the regeneration of potassium carbonate solution in the retort 18, water vapour and a carbon dioxide gas stream 23 at a temperature of about 130"C are formed. This stream is directed toward a valve 25, which can either vent the gases into the atmosphere (as in conventional techniques) through a vent 27, or direct the carbon dioxide and water vapour through a line 29 to dirve a heat engine including a turbine 31 connected to generator 33. Water vapour is used in excess over the stoichiometric amount required in the reaction so that a slurry is formed and the blades of the turbine do not become encrusted with material. The outgoing carbon dioxide and water vapour stream 35 which has been cooled as a result of the work performed can be returned to the top of the treatment column 14 to react with the potassium carbonate solution.

As a result of this configuration, a carbon dioxide stream can be continuously cycled through the system by adjusting the valve 25 to divert outgoing carbon dioxide through the heat engine 31. Using this technique, the retort 18 can be operated even when the carbon dioxide being generated is not used or when the input flue stream 12 has been discontinued. Nevertheless, it is an advantage of the invention that the heat added to the carbon dioxide stream in the retort is at least partially recovered in the form of energy generated by the heat engine 31.

Free hydrogen 37 leaving the treatment column 14 is fed into a reactor 39, which is also fed with a nitrogen stream 41 such that the ratio of hydrogen to nitrogen in the reactor 39 is approximately 3:1, wherein gaseous ammonia 43 is formed. A conventional ammonia reactor may be used and operated conventionally for this purpose.

Ammonia leaving the reactor 39 is directed by a valve 45 along one or both of two different streams. Thus, the formed ammonia can be used directly or be reacted, as in conventional techniques, with sulphuric acid to form ammonia sulphate. This reaction is known, and is shown in dashed lines.

However, according to the invention, rather than reacting the ammonia directly with sulphuric acid, the ammonia is first directed by the valve 45 through a turbine 47 and into reaction chamber 49. In this embodiment, carbon dioxide and water vapour which might otherwise have been vented by vent stream 27 are diverted through the turbine 51 and into the reaction chamber 49, where the carbon dioxide and water vapour are reacted with the ammonia to form aqueous ammonium carbonate. It is the ammonium carbonate solution stream 53 which is then fed into the contact chamber 55, where it is treated with sulphuric acid 57 to form an ammonium sulphate stream 59.

By first forming ammonium carbonate as a reaction intermediate priortoforming the ultimate ammonium sulphate stream, which is desired, it is possible to achieve very desirable energy savings. Since the two gases reacting in the chamber 49 form a solid (in solution) having a substantially reduced specific volume as compared to the two reaction gases, there is a reduced pressure or vacuum exerted by the reaction chamber relative to the line pressures of the reactants, which results in a pressure drop across both turbines 47 and 51. This pressure drop drives each of the turbines, which generate useful energy. Quite obviously, two turbines need not necessarily be used and it is possible, for example, to use only a single turbine positioned in one line.

The chamber 49 is intended to be closed to the atmosphere so that the vacuum exerted upon reaction of the reactants forms a pressure drop across the heat engines. The solution or slurry formed in the reaction chamber may be removed by any conventional means from the stream 61, while maintaining the reduced pressure within the reaction chamber. Sufficient water vapour (in excess of the stoichiometric amount) is used to ensure that a free flowing slurry is formed.

The solution or slurry formed in the reaction chamber may also be treated, be means known to those skilled in the art, to regenerate the NH3, CO2 and water vapour, which can then be recycled through the chamber 49 to drive the turbines and form ammonium carbonate.

According to yet another aspect of the invention, the system may be modified to allow for the storage of the gases which drive the turbines 47 and 51. To do this, vessels 42 and 50 are provided for storing the gases at ambient temperature under pressures sufficient to liquefy the gases. Pressurization means and lines are associated with each of the vessels for this purpose. The valves necessary for diverting the streams into the vessels are schematically illustrated. Storage of the gases may become necessary, as where an oversupply of the products occurs. When the liquefied gases are to be re-gasified, the valves are opened, and the vessels are de-pressurized to permit the gasification of the liquids. According to a preferred embodiment, the vessels may have heat-exchange means associated with their walls.The heat-exchange means may contain a heat-exchange fluid, such as a liquid, adapted to provide at least a portion of the heat necessary for gasification. The fluid is thus cooled, and may be used as a refrigerating fluid.

The principle of the invention is likewise applicable in producing an ammonium carbonate solution 61 as the desired end product. The ammonium carbonate may be stored and used, or subsequently converted to ammonium sulphate by the process of the invention, or any other technique.

It can thus be seen that the system of the invention provides a number of significant advantages over prior processes of forming ammonia, in that the potassium carbonate/potassium bicarbonate loop can be operated continuously, so as to avoid shutting down the retort in the event of system upset. Furthermore, this loop can be operated continuously while not wasting the heat energy supplied to the retort, since the liberated carbon dioxide drives a turbine, which cools the carbon dioxide and recovers useful energy.

Additionally, the system of the invention improves the efficiency of producing ammonia sulphate by first forming a reaction intermediate which creates a pressure drop which can be used to drive at least one turbine, and generate useful energy. The reaction products of the ammonia production process are thus used as working fluids in the generation of power.

For purposes of simplicity, the process of the invention has been described with reference to a complete system, beginning with the initial reactants, and ultimately forming the desired end products (ammonia, ammonium carbonate, or ammonium sulphate). It is to be understood, however, that the invention is not limited to the process as a whole, and extends to the various individual inventive aspects when performed individually.

Furthermore, although described with reference to a particular production scheme, it is clear that the inventive process steps will find application in connection with other flow schemes for providing a wide variety of compounds. To the extent that the inventive principles find other applications in other processes, the use of these principles is deemed to be included within the scope of the invention to the extent to which these principles fall within the scope of the claims.

Claims

1. An apparatus for producing power by forming a product in a reaction chamber from at least two reactants, said product having a lower pressure in said reaction chamberthan the pressure of each of said reactants, comprising: a) at least one line connecting a source of each of said reactants to said reaction chamber: and b) at least one heat engine positioned in at least one of said lines exhausting into said reaction chamber, whereby, upon reaction of said reactants in said chamber, a pressure drop occurs across said at least one heat engine due to the reduced pressure in said reaction chamber.

2. Apparatus as claimed in Claim 1, wherein the heat engine includes a turbine.

3. Apparatus as claimed in Claim 1, comprising two lines, each connected to gaseous reactant sources.

4. Apparatus as claimed in Claim 1, comprising two lines, each connected to gaseous reactant sources, two turbines, one of which is positioned in each of said lines, and one reaction chamber acting as a condenser for each turbine.

5. Apparatus as claimed in Claim 4, and further comprising means for regenerating said reactants from said product and recycling the same to drive at least one of said turbines.

6. Apparatus as claimed in Claim 5 wherein ammonia is the first reactant and a mixture of carbon dioxide and water vapour is the second reactant.

7. A process for generating power by combining ammonia, produced through the combination of hydrogen with nitrogen, with carbon dioxide and water vapour to produce ammonium carbonate.

8. A process as claimed in Claim 7 and further comprising adding sulphuric acid to the ammonium carbonate thus produced to produce ammonium sulphate.

9. A process for the manufacture of ammonium sulphate comprising the steps of: a) reacting ammonia with carbon dioxide and water vapour in a reactor to form ammonium carbonate solution: and b) reacting said ammonium carbonate solution with sulphuric acid to form ammonium sulphate.

10. A process as claimed in Claim 9 comprising passing at least one of the reactants of step a) through a heat engine upstream of said reactor, and exhausting said heat engine into said reactor whereby said reaction in said reactor creates a pressure drop across said heat engine.

11. Apparatus for the manufacture of ammonium sulphate comprising: a) a source of ammonia: b) a source of carbon dioxide: c) a source of water vapour: d) means for feeding said ammonia, carbon dioxide and water vapour into a reaction chamber wherein ammonium carbonate is formed: e) a source of sulphuric acid: and f) means for reacting said ammonium carbonate with said sulphuric acid to form ammonium sulphate.

12. Apparatus as claimed in Claim 11 aand further comprising a heat engine connected between one of said sources of steps a) - c) and said reaction chamber.

13. A process for the manufacture of ammonium carbonate, comprising the steps of: a) passing a reactant stream comprising ammonia gas through a feed line into a reaction chamber: b) passing a reactant stream comprising carbon dioxide gas and water vapour through a feed line into said reaction chamber, at least one of said feed lines having a heat engine in said line: and c) reacting said gases and water vapour in said reaction chamber to form ammonium carbonate solution which exerts a lesser pressure in said reaction chamber than the inlet pressure of both of said reactant streams, thus causing a pressure drop across said at least one heat engine which drives said at least one heat engine.

14. A process as claimed in Claim 13 comprising reacting said ammonium carbonate with sulphuric acid to form ammonium sulphate.

15. A process as claimed in Claim 13 comprising liquefying at least one of said reactants in a vessel, and subsequently expanding said at least one liquefied reactant to form at least one of said reactant streams, and passing said expanded reactant stream through said heat engine.

16. A process as claimed in Claim 15 and further comprising cooling a heat-exchange liquid by contacting said heat-exchange liquid with a wall of said vessel to cool said heat-exchange liquid.

17. A process for the manufacture of ammonia and related products comprising the steps of: a) passing a furnace flue gas comprising hydrogen and carbon dioxide into contact with cooled potassium carbonate solution to form potassium bicarbonate solution and free hydrogen: b) separating and reacting said free hydrogen with nitrogen to form ammonia: c) heating said potassium bicarbonate solution to regenerate potassium carbonate solution while liberating heated carbon dioxide and water vapour: d) recycling and cooling said potassium carbonate solution of step c) for use according to step a: and e) reacting said ammonia of step b) and carbon dioxide and water vapour of step c) to form ammonium carbonate.

18. A process as claimed in Claim 17 further comprising passing at least a portion of said carbon dioxide and water vapour of step c) and said ammonia of step b) through a heat engine prior to the reaction of step e) whereby a pressure drop occurs across said heat engine as a result of said reaction.

19. A process as claimed in Claim 17 comprising reacting said ammonium carbonate with sulphuric acid to form ammonium sulphate.

20. A process for cooling a heat-exchange fluid in the manufacture of ammonia and related compounds comprising: a) liquefying gaseous ammonia, carbon dioxide, and water vapour provided by said process in a vessel: b) expanding said liquefied materials to form gaseous ammonia, carbon dioxide, and water vapour, thereby cooling the wall of said vessel: and c) applying a heat-exchange fluid to the walls of said vessel to cool said heat-exchange fluid.

21. An apparatus for cooling a heat-exchange fluid in the manufacture of ammonia and related compounds comprising: a) one ammonia vessel for liquefying gaseous ammonia: b) one line connecting said ammonia vessel to a source of ammonia, and a second line connecting said ammonia vessel to a reaction chamber: c) one water vapour-carbon dioxide vessel for liquefying gaseous carbon dioxide and water vapour: d) one line connecting said water vapour-carbon dioxide vessel to a source of water vapour and carbon dioxide, and a second line connecting said water vapour-carbon dioxide vessel to said reaction chamber: e) pressurization means for liquefying said gaseous ammonia, carbon dioxide, and water vapour: and f) heat-exchange means associated with each of said vessels whereby heat-exchange fluid is cooled upon the gasification of said liquefied carbon dioxide, water vapour, and ammonia.

22. A process for separating hydrogen gas from carbon dioxide gas comprising: a) treating said carbon dioxide gas, said hydrogen gas, and water vapour with a potassium carbonate solution to form potassium bicarbonate solution: b) separating the hydrogen gas from the potassium bicarbonate solution: c) heating the potassium bicarbonate solution to regenerate potassium carbonate solution while liberating carbon dioxide and water vapour: d) cooling the potassium carbonate solution of step c): and e) cooling and liberated carbon dioxide and water vapour by passing said carbon dioxide and water vapourthrough a heat engine.

23. A process as claimed in Claim 22 wherein the heat engine includes a turbine.

24. A process as claimed in Claim 22 wherein said hydrogen and carbon dioxide gases are coke furnace flue gases.

25. A process as claimed in Claim 22 and further comprising reacting said separated hydrogen gas with nitrogen to form ammonia,

26. A process according to Claim 25 which is further characterized in that at least one of the reactants is passed through a heat engine prior to its reaction with the other reactant whereby a pressure drop occurs across said heat engine as a result of said reaction.

26. A process for operating a potassium carbonate/potassium bicarbonate loop during stand-by operation, said process comprising the steps of: a) contracting gaseous carbon dioxide and water vapour with a potassium carbonate solution to form potassium bicarbonate solution: b) heating said potassium bicarbonate solution to regenerate potassium carbonate solution while liberating heated carbon dioxide and water vapour: c) cooling said potassium carbonate solution of step b): d) recycling and contacting at least a portion of said carbon dioxide and water vapour of step b) with said potassium carbonate solution produced by step c) according to step a): and e) cooling said recycled carbon dioxide and water vapour prior to contact with potassium carbonate solution produced by step c) by passing said carbon dioxide and water vapour through a heat engine to recover at least a portion of the heat contained therein.

27. A process as claimed in Claim 26 comprising recycling all of the heated carbon dioxide and water vapour liberated in step b).

28. A process as claimed in Claim 26 wherein said heat engine comprises a turbine.

29. A potassium carbonate/potassium bicarbonate loop system comprising: a) treatment means for treating gaseous carbon dioxide and water vapour with a potassium carbonate solution to form potassium bicarbonate solution: b) heating means for heating said potassium bicarbonate solution to regenerate potassium carbonate solution while liberating heated carbon dioxide and water vapour: c) cooling means for cooling said potassium carbonate solution: d) recycle means for recycling and treating at least a portion of said carbon dioxide and water vapour of step b) with said potassium carbonate solution of step a): and e) cooling means comprising a heat engine positioned to recover energy from said recycled carbon dioxide and water vapour of step d).

30. A process for forming a product in a reaction chamber from two or more reactants, said process comprising the steps of: a) passing at least one first reactant through a line: b) passing at least one second reactant through a line: c) positioning at least one heat engine in at least one of said lines: and d) reacting each of said reactants to form said product in said reaction chamber connected downstream of said at least one heat engine wherein the pressure in said chamber is less than the pressure of each of said reactants, thereby causing a pressure drop across said heat engine to drive said heat engine.

31. A process as claimed in Claim 30,wherein one of said reactants in a gas.

32. A process as claimed in Claim 30, wherein one of said reactants is a solid.

33. A process as claimed in Claim 30 wherein each of said reactants is a gas.

34. A process as claimed in Claim 30, wherein said product is a gas.

35. A process as claimed in Claim 30, wherein said product is a solid.

36. A process as claimed in Claim 30, wherein said product is a liquid.

37. A process as claimed in Claim 30, wherein said heat engine comprises a turbine.

38. A process as claimed in Claim 30 wherein said first and second reactants include ammonia, water vapour and carbon dioxide and said product is ammonium carbonate.

39. A process as claimed in Claim 30 comprising passing all of said reactants through a single line.

40. A process as claimed in Claim 30 wherein said chamber is a closed chamber.

41. A process as claimed in Claim 30 wherein said reaction in said reaction chamber is exothermic.

42. A process for generating energy by forming a product in a reaction chamber from two or more reactants, and comprising the steps of: a) passing at least one first reactant through a line: b) passing at least one second reactant through a line: c) positioning at least one heat engine in at least one of said lines: d) reacting each of said reactants to form said product in said reaction chamber connected downstream of said at least one heat engine wherein the pressure in said chamber is less than the pressure of each of said reactants, thereby causing a pressure drop across said heat engine to drive said heat engine: e) decomposing said product to said first and second reactants: and f) repeating steps a) - e).

43. A process as claimed in Claim 42 wherein said lines of steps a) and b) are the same line.

44. A process as claimed in Claim 42 comprising decomposing said product into said reactants by heating.

45. An apparatus for forming a product in a reaction chamber from at least two reactants, the product having a lower pressure in said reaction chamber than the pressure of each of said reactants, comprising: a) at least one line connecting a source of each of said reactants to said reaction chamber; and b) at least one heat engine positioned in at least one of said lines exhausting into said reaction chamber whereby upon reaction of said reactants in said chamber a pressure drop occurs across said at least one heat engine due to the reduced pressure in said reaction chamber.

46. Apparatus as claimed in Claim 45, wherein said heat engine includes a turbine.

47. Apparatus as claimed in Claim 45, comprising two lines, each connected to gaseous reactant sources.

48. A process for the manufacture of ammonium sulphate comprising the steps of: a) generating a flue gas containing hydrogen and carbon dioxide: b) treating said flue gas with potassium carbonate in a treatment column to form potassium bicarbonate and free hydrogen: c) heating said potassium bicarbonate solution to liberate carbon dioxide and water vapour while regenerating potassium carbonate: d) cooling the potassium carbonate solution of step c): e) recycling the cooled potassium carbonate of step d) to treat said flue gas as in step b): f) reacting said free hydrogen with nitrogen in an ammonia reactor to form gaseous ammonia: g) passing said ammonia through a first heat engine into a closed reaction chamber: h) passing said liberated carbon dioxide and watervapourthrough a second heat engine into said closed reaction chamber:: i) reacting said ammonia, water vapour and carbon dioxide in said closed reaction chamber to form ammonium carbonate; and j) treating said ammonium carbonate with sulphuric acid to form said ammonium sulphate.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1 to 48 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: CLAIMS

1. Apparatus for producing power from at least two reactants, contained in respective sources, characterized by the provision of respective lines connecting the sources to a reaction chamber, and a heat engine positioned in one of said lines and exhausting into said reaction chamber, whereby, reaction of said reactants in said chamber to form a product reduces the pressure in the reaction chamber and establishes a pressure differential across the heat engine which produces power as the result of the flow of reactant therethrough.

2. Apparatus according to Claim 1, characterized in that said heat engine includes a turbine.

3. Apparatus according to Claim 1, characterized in thatthe reactants are gaseous.

4. Apparatus according to Claim 1 characterized by the provision of a heat engine in the other of said lines.

5. Apparatus according to Claim 4, characterized in that the reactants are gaseous, and that the heat engines are turbines, the reaction chamber acting as a condenser for each turbine.

6. Apparatus according to Claim 5 characterized by the position of means for regenerating said reactants from said product and recycling the same to drive the turbines.

7. Apparatus according to Claim 5 characterized in that gaseous ammonia is the first reactant and a mixture of gaseous carbon dioxide and water vapour is the second reactant, and the product is ammonium carbonate.

8. Apparatus according to Claim 7 characterized by the provision of a contact chamber for contacting the ammonium carbonate with sulphuric acid for producing ammonium sulphate.

9. Apparatus according to Claim 7 characterized by the provision of a storage vessel selectively connectable to one of said lines for liquefying the reactant therein and storing the same for subsequent vaporization and application to the turbine positioned in said one of said lines.

10. Apparatus according to Claim 9 characterized by the provision of a heat-exchange liquid in heat-exchange contact with a wall of said vessel for cooling said heat-exchange liquid when the liquefied reactant is evaporated and applied to the turbine positioned in said one of said lines.

11. A process for producing power using two or more reactants to form a product in a reaction chamber characterized by the steps of: a) passing the reactants to the reaction chamber through respective lines; b) positioning a heat engine in at least one of said lines; and c) reacting each of said reactants to form said product in said reaction chamber located downstream of said at least one heat engine wherein the pressure in said chamber is less than the pressure of each of said reactants, thereby causing a pressure drop across said heat engine to drive the same and produce power.

12. A process according to Claim 11 characterized by the steps of decomposing said product to said first and second reactants, and repeating steps a) - c).

13. Aprocess according to Claim 12 characterized in that the decomposition of said product is carried out by heating the product.

14. A process according to Claim 11 characterized by the following steps: a) generating a flue gas containing hydrogen and carbon dioxide; b) contacting said flue gas with potassium carbonate in a contact column to form potassium bicarbonate and free hydrogen: c) heating said potassium bicarbonate solution to liberate carbon dioxide and water vapour which constitute one of said reactants while regenerating potassium carbonate: d) cooling the potassium carbonate solution of step c): e) contacting the cooled potassium carbonate of step d) with said flue gas as in step b): f) reacting said free hydrogen with nitrogen in an ammonia reactor to form gaseous ammonia which constitutes one of the reactants: g) reacting said ammonia, water vapour and carbon dioxide in said closed reaction chamber to form ammonium carbonate; and h) contacting said ammonium carbonate with sulphuric acid to form said ammonium sulphate.

15. A process for producing power by forming a product in a reaction chamber from two or more reactants characterized by the step of passing at least one of the reactants through a heat engine before the reactants are contacted in the reaction chamber, whereby reaction of said reactants in said chamber to form said product establishes a reduced pressure in the reaction chamber, and creates a pressure differential across the heat engine which produces power as the result of the flow of reactants therethrough.

16. A process according to Claim 15 characterized in that one of said reactants is a gas.

17. A process according to Claim 16 characterized in that one of said reactants is a solid.

18. A process according to claim 15 characterized in that each of said reactants is a gas.

19. A process according to Claim 15 characterized in that the product is a gas.

20. A process according to Claim 15 characterized in that the product is a solid.

21. A process according to Claim 15 characterized in that the product is a liquid.

22. A process according to Claim 15 characterized in that said heat engine comprises a turbine.

23. A process according to Claim 15 characterized in that one of the reactants include ammonia, and another of said reactants includes water vapour and carbon dioxide, and said product is ammonium carbonate.

24. A process according to Claim 15 characterized in that the reaction in said reaction chamber is exothermic.

25. A process for manufacturing ammonia and related products by contacting a furnace flue gas comprising hydrogen and carbon dioxide with cooled potassium carbonate solution to form potassium bicarbonate solution and free hydrogen; separating and reacting said free hydrogen with nitrogen to form ammonia which constitutes a first reactant: heating said potassium bicarbonate solution to regenerate potassium carbonate solution while liberating heated carbon dioxide and water vapour which constitute a second reactant; and cooling said potassium carbonate solution and recycling it into contact with said flue gas; characterized by the step of reacting said first and second reactants to form ammonium carbonate.