High Pressure Direct Contact Oxy-Fired Steam Generator

Abstract

A method and apparatus for direct contact steam generation for a variety of industrial processes including heavy oil recovery, power generation and pulp and paper applications. The steam generation system consists of a combustor and steam generator and is constructed to be operable at elevated pressures. The fuel, at least one oxidant and a fluid supply including water are supplied at pressure to the combustor. Flue gas from the combustor is delivered to the direct contact steam generator at pressure, and upon direct contact with water produces a flue gas stream consisting primarily of steam. This product stream can then be cleansed and used for industrial application. The combustor can be operated with low grade fuel and low quality water with high solids and hydrocarbon contents. The apparatus and method reduce the environmental footprint by reducing air emission, concentrating CO.sub.2 to enable capture and reducing clean water requirements.

Claims

1. An apparatus for direct contact steam generation comprising a combustor and a steam generator operatively connected to the combustor, (a) the combustor being constructed and arranged to be selectively operable at a pressure exceeding atmospheric pressure, and having a first combustor end and a second combustor end, and comprising (i) a combustor wall comprising an outer wall and a refractory liner having an inner surface defining a combustion space; (ii) a burner proximate the first combustor end; (iii) at least a first fuel inlet proximate the first combustor end and constructed and arranged to deliver a first fuel to the burner at a delivery pressure exceeding atmospheric pressure; (iv) at least one oxidant inlet proximate the first combustor end and constructed and arranged to deliver a supply of oxygen to the burner at a delivery pressure exceeding atmospheric pressure; (v) a plurality of fluid inlets operatively connected to the combustion space and constructed and arranged to deliver a supply of a fluid including water at a delivery pressure exceeding atmospheric pressure; and (vi) an outlet region proximate the second combustor end and having a flue gas outlet and a combustor residue outlet; (b) the steam generator having (i) a housing body having a first generator end, a second generator end and an intermediate region; (ii) a steam generation fluid inlet proximate the first generator end and constructed and arranged to receive a supply of steam generation fluid including water at a supply pressure greater than the selected combustor operating pressure; (iii) a flue gas inlet proximate the second generator end and operatively connected to the flue gas outlet of the combustor; (iv) a steam outlet located in the intermediate region between the flue gas inlet and the first generator end and operatively connected to a steam output delivery means; and (v) a residue receiving region proximate the second generator end and having at least one steam generator residue outlet.

2. An apparatus according to claim 1, wherein the supply of fluid includes at least one hydrocarbon material.

3. An apparatus according to claim 1 or claim 2, wherein the refractory liner comprises a set of cooling tubes, and at least one cooling fluid inlet operatively connected to the set of cooling tubes and at least one cooling fluid outlet operatively connected to the set of cooling tubes.

4. An apparatus according to any one of claims 1 to 3, wherein the apparatus further comprises an air separation unit constructed and arranged to be operatively coupled to the at least one oxidant inlet.

5. An apparatus according to any one of claims 1 to 4, wherein the combustor further comprises at least one wash fluid inlet constructed and arranged to selectively deliver wash fluid into the combustor.

6. An apparatus according to claim 5, wherein the combustor comprises at least two wash fluid inlets, constructed and arranged to deliver the wash fluid to contact different surfaces within the combustor including the inner surface of the refractory liner and an inner surface of a region proximate the second combustor end.

7. An apparatus according to any one of claims 1 to 6, wherein the combustor further comprises a water inlet proximate the first combustor end and constructed and arranged to deliver water to the burner at a delivery pressure exceeding atmospheric pressure.

8. An apparatus according to any one of claims 1 to 7, wherein the intermediate region of the steam generator comprises a cleaning zone located between the steam outlet and the second generator end.

9. An apparatus according to claim 8, wherein the cleaning zone comprises at least one of a packed bed, a venturi scrubber, a spray chamber and at least one water reservoir.

10. An apparatus according to any one of claims 1 to 9, wherein the steam generator fluid inlet comprises at least one nozzle, each nozzle having a plurality of jets.

11. An apparatus according to any one of claims 1 to 10, wherein the steam generator further comprises a demister located proximate the steam outlet.

12. An apparatus according to any one of claims 1 to 11, wherein the steam generation fluid comprises water including contaminants.

13. An apparatus according to any one of claims 1 to 12, wherein the steam output delivery means comprises at least one steam quality adjustment means.

14. An apparatus according to claim 13, wherein the steam quality adjustment means comprises a secondary liquid delivery inlet constructed and arranged to deliver a supply of a secondary liquid including water to the steam output delivery means.

15. An apparatus according to any one of claims 1 to 14, wherein the combustor further comprises a steam inlet proximate the first combustor end, and the steam delivery means comprises a recirculation means constructed and arranged to selectively deliver part of the steam output to the steam inlet.

16. An apparatus according to any one of claims 1 to 15, wherein the combustor further comprises at least a second fuel inlet proximate the first combustor end.

17. An apparatus according to any one of claims 1 to 16, wherein the fuel delivered to each fuel inlet is selected from the group consisting of a liquid fuel, a gaseous fuel and a solid fuel and mixtures thereof.

18. An apparatus according to claim 17, wherein the solid fuel is a slurry comprising a liquid and at least one of bitumen, asphaltene, coal, and petroleum coke.

19. An apparatus according to claim 18, wherein the solid fuel is a slurry and comprises an emulsifier.

20. An apparatus according to any one of claims 1 to 19, wherein the outlet region of the combustor comprises a combustor residue grinder.

21. An apparatus according to any one of claims 1 to 20, wherein the combustor has an operable pressure range of between 3 bar and 175 bar, and each fuel inlet, each oxidant inlet and each fluid inlet and each steam generation fluid inlet is constructed and arranged to provide a delivery pressure exceeding each corresponding selected operating pressure of the combustor.

22. An apparatus for direct contact steam generation comprising a combustor constructed and arranged to be operatively connected to a steam generator, wherein the combustor is constructed and arranged to be selectively operable at a pressure exceeding atmospheric pressure, and comprises (i) a first combustor end and a second combustor end; (ii) a combustor wall comprising an outer wall and a refractory liner having an inner surface defining a combustion space; (iii) a burner proximate the first combustor end; (iv) at least a first fuel inlet proximate the first combustor end and constructed and arranged to deliver a first fuel to the burner at a delivery pressure exceeding atmospheric pressure; (v) at least one oxidant inlet proximate the first combustor end and constructed and arranged to deliver a supply of oxygen to the burner at a delivery pressure exceeding atmospheric pressure; (vi) a plurality of fluid inlets operatively connected to the combustion space and constructed and arranged to deliver a supply of a fluid including water at a delivery pressure exceeding atmospheric pressure; and (vii) an outlet region proximate the second combustor end and having a flue gas outlet and a combustor residue outlet; wherein the flue gas outlet is constructed and arranged to deliver a stream of flue gas to the steam generator for direct contact with a steam generation fluid including water to generate a steam product.

23. An apparatus according to claim 22, wherein the supply of fluid includes at least one hydrocarbon material.

24. An apparatus according to claim 22 or claim 23, wherein the refractory liner comprises a set of cooling tubes, and at least one cooling fluid inlet operatively connected to the set of cooling tubes and at least one cooling fluid outlet operatively connected to the set of cooling tubes.

25. An apparatus according to any one of claims 22 to 24, wherein the apparatus further comprises an air separation unit constructed and arranged to be operatively coupled to the at least one oxidant inlet.

26. An apparatus according to any one of claims 22 to 25, wherein the combustor further comprises at least one wash fluid inlet constructed and arranged to selectively deliver wash fluid into the combustor.

27. An apparatus according to claim 26, wherein the combustor comprises at least two wash fluid inlets, constructed and arranged to deliver the wash fluid to contact different surfaces within the combustor including the inner surface of the refractory liner and an inner surface of a region proximate the second combustor end.

28. An apparatus according to any one of claims 22 to 27, wherein the combustor further comprises a water inlet proximate the first combustor end and constructed and arranged to deliver water to the burner at a delivery pressure exceeding atmospheric pressure.

29. An apparatus according to any one of claims 22 to 28, wherein the combustor further comprises a steam inlet proximate the first combustor end, and the steam delivery means comprises a recirculation means constructed and arranged to selectively deliver part of the steam output to the steam inlet.

30. An apparatus according to any one of claims 22 to 29, wherein the combustor further comprises at least a second fuel inlet proximate the first combustor end.

31. An apparatus according to any one of claims 22 to 30, wherein the fuel delivered to each fuel inlet is selected from the group consisting of a liquid fuel, a gaseous fuel and a solid fuel and mixtures thereof.

32. An apparatus according to claim 31, wherein the solid fuel is a slurry comprising a liquid and at least one of bitumen, asphaltene, coal, and petroleum coke.

33. An apparatus according to claim 31, wherein the solid fuel is a slurry and comprises an emulsifier.

34. An apparatus according to any one of claims 22 to 33, wherein the outlet region of the combustor comprises a combustor residue grinder.

35. An apparatus according to any one of claims 22 to 34, wherein the combustor has an operable pressure range of between 3 bar and 175 bar, and each fuel inlet, each oxidant inlet and each fluid inlet and each steam generation fluid inlet is constructed and arranged to provide a delivery pressure exceeding each corresponding selected operating pressure of the combustor.

36. A method of direct contact steam generation comprising the steps of (a) providing (i) a combustor having a burner and a refractory wall defining a combustion space and operable at a combustor operating pressure exceeding atmospheric pressure; and (ii) a steam generator operatively connected to the combustor and having an upper region, a lower region and an intermediate region; (b) performing a pre-heating process at ambient pressure to raise the temperature of the refractory wall to a selected temperature; (c) delivering a fuel and a supply of oxygen to the burner at a pressure exceeding a selected combustor operating pressure; (d) burning the fuel and oxygen at the selected combustor operating pressure and substantially concurrently delivering to the combustion space a supply of a fluid including water at a pressure exceeding the selected combustor operating pressure to produce a stream of flue gas and a combustion residue; (e) delivering the stream of flue gas to the lower region of the steam generator and substantially concurrently delivering to the upper region a supply of steam generation fluid including water at a pressure exceeding the selected combustor operating pressure; (f) allowing the flue gas to contact the steam generation fluid to produce a stream of generated steam; and (g) removing the stream of generated steam from the steam generator.

37. A method according to claim 36, wherein the selected combustor operating pressure is at least 3 bar.

38. A method according to claim 37, further comprising after step (b) the step of (b.1) providing a supply of nitrogen to the combustor to attain the selected combustor operating pressure, and the burning in step (d) maintains the selected combustor operating pressure.

39. A method according to claim 37, wherein the burning in step (d) is performed to attain and maintain the selected combustor operating pressure.

40. A method according to any one of claims 36 to 39, wherein the fuel in step (c) is selected from the group consisting of a liquid fuel, a gaseous fuel and a solid fuel and mixtures thereof.

41. A method according to claim 40, wherein the solid fuel is a slurry including at least one of bitumen, asphaltene, coal, and petroleum coke.

42. A method according to claim 41, wherein the solid fuel is a slurry and comprises an emulsifier.

43. A method according to any one of claims 36 to 42, wherein step (c) further includes providing a supply of water to the burner at a pressure exceeding the selected combustor operating pressure.

44. A method according to any one of claims 36 to 43, wherein in step (d) the fluid includes at least one hydrocarbon material.

45. A method according to any one of claims 36 to 44, wherein the combustor operating pressure is selected from between 3 bar and 175 bar.

46. A method according to any one of claims 36 to 45, wherein the supply of oxygen has a purity of at least 80%.

47. A method according to claim 46, wherein the supply of oxygen has a purity between 90% and 100%.

48. A method according to claim 47, wherein the supply of oxygen has a purity between 95% and 100%.

49. A method according to any one of claims 36 to 48, wherein step (a)(ii) further comprises providing a cleaning zone in the intermediate region of the steam generator.

50. A method according to claim 49, wherein the cleaning zone comprises at least one of a packed bed, a venturi scrubber, a spray chamber and at least one water reservoir.

51. A method according to any one of claims 36 to 49, wherein the steam generation fluid delivered in step (e) further comprises a sorbent comprising an alkali element selected from calcium, magnesium, sodium and potassium.

52. A method according to claim 51, wherein the alkali element is in a compound form selected from a hydroxide and a carbonate.

53. A method according to any one of claims 36 to 52, further comprising after step (f) the step of (f.1) passing the generated steam through a demisting region.

54. A method according to any one of claims 36 to 53, wherein in step (e) the steam generation fluid comprises water including contaminants.

55. A method according to any one of claims 36 to 54, wherein step (g) further comprises at least one adjusting of quality of the stream of generated steam.

56. A method according to claim 55, wherein the at least one adjusting of quality comprises providing a supply of a secondary liquid including water to the steam output.

57. A method according to any one of claims 36 to 56, wherein step (g) comprises separating the steam output into a primary output and a secondary output, and recirculating at least part of the secondary output to the combustor.

58. A method according to any one of claims 36 to 57, further comprising the steps of (h.1) selectively periodically removing residue from the combustor; and (h.2) selectively periodically removing residue from the steam generator.

59. A method according to any one of claims 36 to 58, wherein steps (d) and (e) further comprise concurrently substantially continuously removing residue from the combustor.

60. A method according to any one of claims 36 to 59, wherein steps (f) and (g) further comprise concurrently substantially continuously removing residue from the steam generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0104] The invention will now be described with reference to the drawings, in which:

[0105] FIG. 1 is a schematic representation of an embodiment of the invention;

[0106] FIG. 2 is a schematic cross-sectional view of the combustor of an embodiment of the invention; and

[0107] FIG. 3 is a schematic cross-sectional view of the combustor of a second embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0108] Referring first to FIG. 1, an embodiment of the apparatus 1 of the invention is shown, including a combustor 10 and a steam generator 70. The combustor 10 comprises a first end shown generally at 12, a second end shown generally at 14, and an outer wall 16. Within the outer wall 16, a refractory liner 18 (shown in detail in FIGS. 2 and 3) defines the combustor chamber 50. In the embodiment shown, the combustor 10 has a substantially vertical operational position, such that the first end 12 will be at the upper end and the second end 14 will be at the lower end, but other orientations are possible.

[0109] Near the first end 12 of the combustor 10, and directly operatively connected to the combustor chamber 50, is the burner region 32, within which is a burner (not shown). Various inlets are provided at the inlet end 34 of the combustor 10 to the burner region 32, including at least one fuel inlet 36, oxygen inlet 38, and water inlet 40, each of which is designed to deliver its respective input supply at a pressure sufficiently in excess of the contemporaneous pressure of the combustor 10 and burner, such that the input supply will flow into the burner at the desired rate. The other inlets shown in FIG. 1 are a pre-heat fuel inlet 42, an igniter 44, recirculated steam inlet 46, and upper ash purge water inlet 48; additional known inlets and features can be provided as required.

[0110] Downstream from inlet end 34 of the combustor 10, at least one inlet 54 is provided to deliver to the combustor chamber 50 a fluid supply which includes water, and may include dissolved, suspended or entrained solids, which can include hydrocarbons. Further inlet 26 and outlet 28 provide for additional flows of water or other thermal fluid to regulate the operating temperature of the combustor 10 to the desired range; and lower ash purge water inlet 52 is provided for purging the lower region at the second combustor end 14.

[0111] At the downstream end of the combustor chamber 50, flue gas outlet 60 delivers the flue gas supply from the combustor 10 to flue gas inlet 96 of the steam generator 70.

[0112] At or near the second end 14 of the combustor 10, a lower outlet 62 is provided, for the selected discharge of residue, including solids such as ash, and together with any purge fluid delivered to the chamber through either of the ash purge water inlets 48 or 52.

[0113] Steam generator 70, also shown in this embodiment as having a substantially vertical position, has a first (upper) end 72, a second (lower) end 74, and an intermediate region 76. At the first end 72, fluid inlet 80 is provided to deliver a supply of water to at least one nozzle 82, each nozzle having a plurality of jets 84.

[0114] Above the second end 74, flue gas inlet 96 is operatively connected to flue gas outlet 60 on combustor 10, to receive the flue gas supply into steam generator 70, the flue gas thereafter moving upwards to come into contact with the supply of water through the jets 84, as discussed further below. At or near the second end 74, recirculated water outlet 98 provides for the removal of any accumulated water, and blowdown 78 provides for selective removal of any other residue.

[0115] Between the flue gas inlet 96 and the jets 84, in an appropriate location in the intermediate region 76, a scrubber 90 (not shown in detail) can optionally be provided to collect any solid particles from the flue gas. The scrubber can be of any known type, such as a packed bed, venturi scrubber, or a spray chamber or one or more water reservoirs.

[0116] Towards the first end 72 of the steam generator 70, and below the jets 84, steam outlet 86 is provided. At or close to the outlet 86, a demister 88 can be provided to prevent larger droplets of water passing through the outlet with the steam and into the steam product delivery pipe 100. Product delivery pipe 100 can be provided with a recirculated steam outlet 94, for selective diversion of part of the steam product back to the recirculated steam inlet 46 in the combustor 10. Optionally, product delivery pipe 100 can also be provided with a quality adjustment means 92, which can include an inlet for delivery of water to the steam, to increase its liquid content where required.

[0117] Referring now to FIG. 2, the construction of combustor 10 is shown in more detail, in particular in relation to the cooling of the outer wall 16 of the combustor chamber 50. As noted above, the outer wall 16 is provided with a refractory liner 18, which can comprise a single material, or multiple materials. In FIG. 2 the liner is shown as comprising an outer portion 20 and an inner portion 22, by and between which are secured a plurality of cooling tubes 24, each having a central bore to provide a flow path 30 for a suitable coolant fluid, for example water, and each being operatively connected to an inlet 26 and outlet 28 via inlet header 56 and outlet header 58, respectively.

[0118] The method and operation of the apparatus of the invention are as follows.

[0119] Prior to raising the combustor 10 to a selected operating pressure from ambient atmospheric pressure, a pre-heating step is performed, by delivering a flow of pre-heat fuel through the pre-heat fuel inlet 42, to raise the temperature of the wall of the refractory liner 18, which assists in ignition. Suitable pre-heat fuels would include liquid or gaseous fuels, such as natural gas, or No. 2 fuel oil.

[0120] After the pre-heat step, either a supply of nitrogen is delivered above the desired combustor operating pressure into the combustor chamber 50 which raises the pressure, followed by a supply of fuel and oxygen at inlets 36 and 38 respectively, each at a pressure exceeding the combustor pressure; or the supply of fuel and oxygen is commenced while the combustor 10 is still at ambient pressure, and the pressure is raised by the burning of the fuel with oxygen while restricting the flow of the product stream 100. Concurrently with the flow of fuel and oxygen, small amounts of water can be added through water inlet 40 as needed to moderate the flame and regulate the temperature of the tip of the burner. Where nitrogen is used to raise the pressure, the amount required for the brief period is small, so that its effect on the end steam product is minimal and can generally be regarded as negligible.

[0121] As noted above, fuels for the combustion operation can be any of a wide range of liquid, gaseous or solid fuels. However, it is particularly advantageous for environmental and economic reasons to use the solid fuels which have few or less economically viable uses for other purposes, such as bitumen, asphaltene, coal, and petroleum coke. If these solid fuels are used, they are preferably delivered in the form of a slurry, which may also include an emulsifier.

[0122] The oxygen delivered to the oxygen inlet 38 can be supplied from commercial containers, or by pipeline, or in situations where feasible, can be prepared by a physically adjacent air separation unit.

[0123] The supply of fluid is introduced to the combustor chamber below the burner, through inlets 54. Any contaminants in the fluid, including hydrocarbons, are combusted with the fuel from inlet 36, to form a steady stream of flue gas, which is discharged from the combustor 10 through flue gas outlet 60, and a combustion residue which travels through the lower region of the combustor and to the second end 14.

[0124] The combustor can be operated at any desired pressure, within any operating range above atmospheric pressure up to at least 175 bar. The selection of the combustor pressure will be determined by factors depending on the field of use.

[0125] The flue gas discharged from flue gas outlet 60 is delivered to flue gas inlet 96 located in the lower part of the intermediate region 76 of the steam generator 70. As the flue gas rises in the steam generator, it comes into contact with the stream of water which is supplied through the fluid inlet 80 and delivered into the generator 70 through the nozzle 82 and jets 84. The heat of the flue gas vaporizes the water into steam, which passes demister 88, which removes any large water droplets, and is discharged through steam outlet 86, into steam product delivery pipe 100. Shortly after the steam passes into the product delivery pipe 100, it can be subjected to a quality adjustment by quality adjustment means 92, for example to add liquid water content where needed for the specific intended end use. For example, where the steam is to be used in a SAGD process, additional liquid water in the steam product on delivery into the shaft will facilitate flushing solids down the shaft.

[0126] Optionally, some of the steam product can be diverted from the flow in the product delivery pipe 100, to be recirculated through the recirculated steam outlet 94 back to the recirculated steam inlet 46 for use in the combustor 10.

[0127] As noted above, a scrubber 90 can be provided in the intermediate region 76 of the steam generator 70; as noted above, the scrubber 90 can be of any known type, such as a packed bed or venturi scrubber, or a spray chamber or a bubbling means such as one or more water reservoirs. In such embodiment, the flue gas passes through the scrubber 90, which removes residual particulate matter from the flue gas as it comes into contact with the water delivered to the steam generator 70 by the jets 84 and flows through the scrubber.

[0128] Optionally, a supply of a suitable sorbent material such as the alkali elements calcium, magnesium, sodium and potassium, in various forms (typically hydroxides or carbonates) can be added into the steam generation fluid before delivery into the fluid inlet 80, to assist in removing any acids in the flue gas stream.

[0129] Any residual water which may not be converted to steam by the flue gas will fall towards the second end 74 of the steam generator 70, together with any solid residues. Residual water collected in the second end 74 of the steam generator 70 may be recirculated through the recirculated residual water outlet 98 to the fluid inlet 80. The residual solids can be discharged periodically as required through the blowdown 78.

[0130] Similarly, the accumulation of residues such as ash on the walls of the combustor chamber 50 is addressed by periodic purging through the upper ash purge water inlet 48; and accumulations at the second end 14 of the combustor 10 can be addressed by delivery of additional fluid through the lower ash purge water inlet 52, either periodically or through a continuous discharge.

[0131] Optionally, a grinder (not shown) of known construction can be provided closely adjacent to the lower outlet 62, to reduce any accumulations of solids.