Thermodynamic/Solar Steam Generator

Abstract

Disclosed is a process for generating and superheating steam.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of U.S. Prov. Pat. App. Ser. No. 61/275,005 (filed Aug. 24, 2009) entitled “Thermodynamic/Solar Steam Generator,” which document is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

1. Field of Invention

The present application is in the field of superheated steam generation.

2. Background of the Invention

Steam generation plus the subsequent expansion of said steam against a turbine blade is a known process for converting heat into work. Within said process, steam generation has typically been accomplished via heating water to its boiling point and until it has phase-changed to steam. For efficiency reasons, the generated steam may be heated to a higher temperature than the boiling point temperature (i.e., superheated) so that heat lost during the expansion of said steam against a turbine blade does not result in condensation of the steam on the turbine blade. Instead, the steam preferably attains saturation (i.e., a temperature and pressure at which the steam would condense with additional heat loss) after its expansion against the turbine blade. Accordingly, there is a need for processes and related apparatus for heating water through a phase-change and superheating the resultant steam.

Processes now exist for heating water through a phase-change and superheating the resultant steam. The heat resulting from the combustion of fossil-fuel or biomass has been effectively used to generate and superheat steam. However, combusting fossil-fuels or biomass has been viewed as an inadequate heat source for producing steam due to combustion by-products' alleged detrimental effects on the environment and climate. The heat resulting from nuclear fission has also been effectively used to generate and superheat steam, but the resulting nuclear waste is extremely hazardous so that nuclear fission has not yet been viewed as an entirely adequate steam-generating heat source. Geothermal heat may also be used for generating and superheating steam, however, geothermal access points are not abundant and may not provide enough heat to generate a sufficient amount of steam. Finally, the heat resulting from focused solar light is yet another known means for generating and super heating steam, but solar light is an inadequate heat source since: (1) solar light is periodically unavailable; and, (2) methods for focusing solar radiation to produce steam, for example a conductive pipe through the focal point of a parabolic-trough mirror, evaporate flowing water within a pipe causing a two phase water/steam flow that is unstable (Ledinegg Instability) and difficult to control. Accordingly, there is a need for systems and methods of steam generation and superheating which avoid or minimize the above mentioned inadequacies of the known methods.

U.S. Pub. Pat. App. No. 2010/0154417 (published Jun. 24, 2010) discloses various hybrid methods for generating and superheating steam. In one embodiment, geothermal energy is used to generate saturated steam while solar radiation is focused on a conductive pipe via a parabolic-trough mirror in order to heat a working fluid (e.g., oil) for subsequent heat-exchange to superheat said saturated steam. See paragraphs [028], [029], and [021]. Although the disclosed geothermal/parabolic-trough hybrid system is said to be an advancement over non-hybrid steam generation, the system is not entirely preferable since an intermediate working fluid is employed. Use of such intermediate working fluids poses risks of hazardous spills, difficulty with VOC emissions permitting, and requires proper handling and disposal. For this reason there is still a need for improved systems and methods of generating and superheating steam.

SUMMARY OF THE INVENTION

It is an object of the present application to disclose improved systems and methods for generating and superheating steam. A preferable system includes a flow of superheated steam, a flow of water, a valve for mixing said flows to produce a stream of saturated steam, and means for focusing solar radiation to superheat the stream of saturated steam. In a suitable embodiment, the means for focusing solar radiation to superheat saturated steam is a conductive pipe through the focal point of a parabolic-trough mirror or a Fresnel lens. A preferable method includes the steps of: mixing water with superheated steam to produce saturated steam; and, directing said saturated steam through a tube at the focal point of a parabolic-trough mirror to superheat said saturate steam.

It is yet another object of the present application to meet the aforementioned needs without any of the drawbacks associated with apparatus heretofore known for the same purpose. It is yet still a further objective to meet these needs in an efficient and inexpensive manner.

BRIEF DESCRIPTION OF THE FIGURES

The manner in which these objectives and other desirable characteristics can be obtained is better explained in the following description and attached figures in which:

FIG. 1 diagram of a preferable system embodying this disclosure.

It is to be noted, however, that the appended figures illustrate only typical embodiments disclosed in this application, and therefore, are not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that will be appreciated by those reasonably skilled in the relevant arts. Also, figures are not necessarily made to scale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In general, this application discloses a preferable system including superheated steam, water, a valve for mixing said water and superheated steam to produce a stream of saturated steam, and means for focusing solar radiation to superheat the stream of saturated steam. A diagram of the preferable system is depicted in FIG. 1

Referring to FIG. 1, water (M2) at a first temperature (T2) may be introduced into an existing superheated steam flow (M1) at a second temperature (T1) to produce a stream of saturated steam (M1+M2) at a third temperature (T3). The existing superheated steam (M1) may be produced in any manner known to one of skill in the art, including but not limited to, geothermal, solar, or the combustion of fossil fuels or biomass. Operably, the water (M2) suitably increases in temperature to the saturation temperature (T3) and evaporates into steam via the transfer of thermal heat from the superheated steam (M1). Correspondingly, the temperature (T1) of the superheated steam (M1) decreases to the saturation temperature (T3) as a result of said heat transfer. Suitably, the amount of water (M2) introduced is restricted so as not to reduce steam (M1+M2) temperature (T3) to below the saturation point. Valves acceptable for introducing the water (M2) to the superheated steam (M1) will be known to those of skill in the art, but can include those having the general design of U.S. Pat. No. 3,509,857 (issued May 5, 1970). Preferably, the resultant saturated steam (M1+M2) passes through a heat conductive tube (pipe) at the focal point of a mirror (including parabolic trough mirrors) so that concentrated light or solar radiation (L) may increase the temperature of the steam (M1+M2) to a superheated temperature (T4). In an alternate embodiment, a Fresnel lens (or other device that collects and concentrates thermal solar energy) may be used to focus the solar radiation (L) onto a heat conductive pipe.

The superheated steam (M1+M2, T4) may thereafter be used for whatever purpose including, but not limited to: (1) for expansion against a turbine blade; or (2) for the existing superheated steam flow (M1).

The following Table 1 quantitatively discloses the preferable system:

	TABLE 1
		Flow rate	Temp	Enthalpy	Pressure
		(kg/hr)	(deg. C.)	(kj/kg)	(bar)
	M1, T1	45359	395	3142	70
	M2, T2	7118	115	488	80
	M1 + M2, T3	52477	287	2782	70
	M1 + M2, T4	52477	395	3142	70

It should be noted that FIG. 1 and the associated description are of illustrative importance only. In other words, the depiction and descriptions of the present invention should not be construed as limiting of the subject matter in this application. Additional modifications may become apparent to one skilled in the art after reading this disclosure.

Claims

1. A system for generating and superheating steam comprising:

superheated steam;

water;

a valve for mixing the superheated steam with the water so that the resultant mixture is saturated steam; and,

a means for superheating the saturated steam.

2. The system of claim 1 wherein the means for super heating the saturated steam is a parabolic-trough mirror and a heat transferring pipe directed through the focal point thereof.

3. The system of claim 1 wherein the means for super heating the saturated steam is a Fresnel lens and a heat transferring pipe directed through the focal point thereof.

4. A system for generating and superheating steam comprising:

a first flow of superheated steam;

a second flow of water;

a valve for mixing said first and second flows so that the resultant mixture is a third flow of saturated steam; and,

a means for superheating said third flow.

5. The system of claim 4 wherein the means for super heating the saturated steam is a parabolic-trough mirror and a heat transferring pipe directed through the focal point thereof.

6. The system of claim 4 wherein the means for super heating the saturated steam is a Fresnel lens and a heat transferring pipe directed through the focal point thereof.

7. A method of generating superheated steam from water comprising the steps of:

introducing water into an existing flow of superheated steam so that the resultant mixture is saturated steam;

directing said resultant mixture through a heat conductive pipe; and

focusing solar radiation thereon the pipe until said resultant mixture is superheated.

8. The method of claim 7 wherein said existing flow of superheated steam was superheated via combusting biomass or fossil fuels.

9. The method of claim 7 wherein said existing flow of superheated steam was superheated via the heat of nuclear fission.

10. The method of claim 7 wherein said existing flow of superheated steam was geothermally superheated.

11. The method of claim 7 wherein the step of focusing solar radiation is accomplished via at least one parabolic-trough mirror.

12. The method of claim 7 wherein the step of focusing solar radiation is accomplished via at least one Fresnel lens.

13. The method of claim 8 wherein the step of focusing solar radiation is accomplished via at least one parabolic-trough mirror.

14. The method of claim 8 wherein the step of focusing solar radiation is accomplished via at least one Fresnel lens.

15. The method of claim 9 wherein the step of focusing solar radiation is accomplished via at least one parabolic-trough mirror.

16. The method of claim 9 wherein the step of focusing solar radiation is accomplished via at least one Fresnel lens.

17. The method of claim 10 wherein the step of focusing solar radiation is accomplished via at least one parabolic-trough mirror.

18. The method of claim 10 wherein the step of focusing solar radiation is accomplished via at least one Fresnel lens.