Patent Application
20220090519
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This patent application is for a design that is in the field of low emissions (zero harmful emissions) power generation, specifically for a boiler system that can be used in existing or new power plants to supply high-pressure steam to steam turbines, which in turn produce shaft power that drives electrical generators that send the power out to power generation utility customers. This design can produce enough steam to drive a wide range of boiler-driven steam turbines, up to 1200 MW in output, while eliminating all of the harmful emissions associated with current coal-burning, natural gas-burning, refuse-burning, and biomass-burning boiler systems, including greenhouse gases like carbon dioxide, methane, and nitrous oxide, lethal poisons like carbon monoxide, small particulate matter, large particulate matter, volatile organic compounds, hydrogen sulfide, radioactive waste, and carbon black, and known pollutants like sulfur dioxide, nitrogen dioxide, and unburned hydrocarbon molecules and fragments. The only emissions will be steam, water vapor, and unburned atmospheric gases like oxygen and hydrogen, all harmless to humans, plants, animal life, and the world's climate. Power generation companies today have to spend huge amounts of cash designing and building complex emissions control equipment for their boilers. This design can eliminate 100% of that emissions control equipment which, over the past decades, has often cost more to build than the entire rest of the plant combined.
Specifically this design uses the combustion of liquid hydrogen and liquid oxygen to produce steam in the boiler. There are no such designs on the market today, but the availability of those two fuels is increasing dramatically every year, and their price is now within reach of utility companies all over the world, which was not the case just one or two years ago.
The USPTO search of prior related patents requested by the inventor in this application procedure produced two patents and two patent applications. The inventor will discuss each of these in chronological order.
The first two are U.S. Pat. No. 5,761,896-A, by Thomas Dowdy, from June, 1998, and U.S. Pat. No. 5,953,900-A, by Roger Bannister, from September, 1999. As more than twenty years has elapsed since these two patents were approved, they are no longer in force.
Both are patents for power plant combustion turbines, rather than boiler systems. The inventors, both of whom worked for the same company, Westinghouse, were trying to design combustion turbines that burn a variety of fuels, including air, gaseous oxygen, gaseous hydrogen, liquid oxygen, and liquid hydrogen. Their designs sometimes included compressors, sometimes included combustors, and were often cooled with water. They were apparently attempting to patent a whole range of different designs. Most of the descriptions pertain to gaseous fuels, rather that cryogenic fuels, and the patents contain no descriptions whatsoever of cryogenic tanks, lines, valves, pumps, sensors, actuators, or burners. In fact, each of them only uses a few short words and phrases to describe cryogenic fuels, their basic approach is to describe gaseous fuel usage. Bannister's, for instance, is a series of three turbines, a high-pressure turbine, an intermediate pressure turbine, and a low pressure turbine. The specifications quoted for the steam in the combustor for the high pressure turbine are 250 bar (3675 psi) and 1600 C. degrees (2912 degrees F.). It is not clear exactly what materials he planned to use, what kind of pumps he planned on using to inject fuel at that pressure, or what kind of injection system he had planned. Whatever they were, they were probably not something that could be built and operated today. No models of these designs exist at this time, perhaps for that reason.
The third source cited is patent application US-20140283499-A1, by Jean-Michel Sannino, dated September, 2014. This one, by an employee of SNECMA, is for submerged electrical booster pumps in cryogenic fuel tanks in rocket designs, particularly hydrogen tanks. This inventor is also attempting to patent multiple designs with one application; there are at least a dozen variations in the copy and drawings, and the designs include several variations on turbopumps, in addition to the electrical pumps. It appears to be potentially workable if the inventor can find pumps that work submerged in cryogenic hydrogen at about 15 Kelvin or so (−432.67 degrees F.). A pump like that would require very specialized lubricants, materials, parts, wiring, and electrical connections, no question about it. However, it is a rocket design, intended for use in extremely short bursts with a limited power range, often a few minutes or less, and as such is probably not suitable for power generation use.
The fourth source cited is patent application US-20200072458-A1 by Joshua Partheepan, dated March, 2020. This one is a long application that describes what could be over a thousand potential variations in a steam-production scheme that may be patterned after the kind of pre-mixed gaseous hydrogen and gaseous oxygen found in oxyhydrogen welding equipment. This is a quote from the application
Thus his “pre-mixed” design is totally different from the zero emissions boiler design described in this application, which is, to use his own term, a “post-mixed” design. He hits the nail on the head with those lines. It does not appear as though he can produce significant steam pressure with his pre-mixed design and also avoid pre-combustion and explosions. This is another quote from his application:
It is not quite clear what he is referring to, possibly old-style steam engines or possibly steam turbines in trucks, tanks, trains, etc.
Whatever it is, it does not appear to be a workable design for producing steam for modern steam turbines in power plants. He does not give one single temperature, pressure, or flow rate specification in the entire application, leaving us to guess at all of that. The current guess is that the maximum pressure he can achieve with any of the thousand or so variations in his designs, including eleven different fuel storage methods, would be around 50-100 psi, if that, possibly enough for a small turbine but nowhere near enough for power plant steam turbines that run at 1000-5000 psi or so.
This is a design for a power plant steam boiler that runs on the combustion of liquid hydrogen and liquid oxygen. The combustion takes place in a large unit equipped with burners, a sparking system, a water cooling system, and a steam header that transfers pressurized steam from the boiler to the steam turbine and generator system. The two cryogenic fuels are sent to the boiler at variable pressure (up to 6000 psi) by cryogenic fuel pumps. The cooling water is pumped in just under boiling temperature (around 205-210 F) at even higher pressures (5000-20,000 psi), after being heated by a heat exchanger and a boiler pre-heat cycle. The boiler is designed to produce steam at around 1000-1200 F at pressures of around 1000-4500 psi, at flow rates of up to 10 million pounds of steam per hour, or higher if necessary. The boiler and cryogenic tanks, pumps, valves, and lines are designed to work well at cryogenic temperatures without failure. The system operates off of large liquid hydrogen, liquid oxygen, and water holding tanks. The entire system is equipped with pressure relief valves, check valves, blowback suppression valves, temperature sensors, pressure sensors, flow rate sensors, strain gauges, purging equipment, boil-off re-liquefaction equipment, fuel tank cooling equipment, booster pumps, and equipment that can relay actuator and sensor information and controls to a central power plant control room. It is designed to correct itself with a minimum of manual control.
This boiler design can also be outfitted with modern re-heat and double re-heat systems, as required by the customer. It can be sized and built to run everything from small 20 MW steam turbines up to large 1200 MW steam turbines. It can be designed for brand-new power plants or designed as a retrofit installation for existing power plants, as a replacement for fossil fuel and renewable boiler systems. It can be run as a stand-alone design or as part of a combined cycle design where the exhaust from a combustion turbine is used as part of the water pre-heating system. This design completely eliminates the emission of harmful pollutants, poisons, and greenhouse gases, and in doing so also eliminates the need for large and extremely expensive emissions control systems.
There are eight drawings in this submission, two perspectives, one cutaway perspective section, one plan, and four elevations.
This is a perspective rendering with a view from the upper right rear of the project. It shows the general layout of the boiler, the steam turbine and generator, the water pumps, and the cryogenic fuel pumps, plus the upper part of the water preheat system. The drawing does not show power plant roofs and walls, the fuel holding tanks, the water holding tank, the water cooling ponds, the turbine steam outlets, the condenser, or the stack as these are not a part of the current application. The steam turbine and generator are shown because the connections and reheat system are a part of this application. The turbine shown is based on a Siemens steam turbine design, and its design is not a part of this application.
This is a perspective rendering with a view from the upper left front of the project, showing the back end of the generator, turbine, reheat system, steam header, and boiler. It should be noted that the water pumps shown in these views are a reciprocating design based on pumps sold by GD Energy Products, their Thunder 5,000 HP Quintuplex model, and their design is not a part of this application.
This is a cutaway perspective section with a view from the upper right rear side of the project. The outer casing of the boiler is cut away showing the double shell with a thinner outer shell and thicker inner shell, air-cooled from the outside. It shows a preliminary design for the upper part of the water pre-heat system (the lower part, not shown, is a customer option, either a combined cycle system or a stand-alone heat exchanger system). Inside the boiler walls are the water cooling system (outer rows of inlets) and the sparking and burner system (inner rows of electrical units and fuel injectors).
The plan view is a bird's eye view of the project, showing the general layout of the boiler, pumps, and steam turbine. The inner ring of pumps are alternating high pressure liquid hydrogen and liquid oxygen pumps of a multi-stage design powered by electric motors. These will have to be a custom design for this project.
This elevation view shows the project from the right side. The boiler, steam header, and steam turbine can be clearly seen.
This elevation view shows the project from the rear. The upper part of the water preheat system can be seen in front of the boiler.
This elevation view shows the project from the left.
This elevation view shows the project from the front.
This zero [harmful] emissions power generation boiler is being designed as a potential replacement for power plant boilers all over the world that drive steam turbines by boiling water using nuclear fission or the combustion of coal, natural gas, fuel oil, biomass, and garbage. The idea is to replace all of the harmful emissions and by-products of those systems, including greenhouse gases like carbon dioxide, methane, and nitrous oxide; poisons like radioactive waste, small particulate matter, carbon monoxide, hydrogen sulfide, large particulate matter, volatile organic compounds, and carbon black; and known pollutants like nitrogen dioxide, sulfur dioxide, unburned and partially burned hydrocarbons, coal ash, spent nuclear fuel rods, and unburned waste with emissions that are nothing but water, water vapor, steam, oxygen, and hydrogen, the latter two pure atmospheric gases. The idea is to take the current deadly mix, responsible for around 10-50% of the world's air pollution and greenhouse gas emissions today, depending on the nation involved, a mix which plays a part in millions of fatalities worldwide every year, and replace it with a system whose emissions are completely harmless to humans, plants, and animals.
This can be accomplished by this design in a manner that does not decrease, in any way, the potential power or efficiency of modern power plants. In doing so it can totally eliminate the massively expensive and space-consuming scrubbers and emissions control equipment that today can cost more than the entire thermal energy plant they are designed around, and replace immensely expensive and often quite dangerous nuclear power plants near highly populated areas.
Today the world is witnessing a quiet revolution in energy production, in which green hydrogen and its companion product, oxygen, are starting to replace traditional fossil fuels, biomass, and garbage as combustibles. The price of those two fuels is now beginning to come down to a level that can make their use competitive with their rivals. Fuel costs are often fifty percent of the running costs of a typical power plant. The day is dawning, as natural gas and fuel oil prices skyrocket this year, as highly-polluting brown coal [lignite] is the only form of coal utility companies can afford to burn any more, as biomass and garbage are starting to be recognized for the dangerous polluters that they really are in practice; and as nuclear plants continue to get more and more expensive, when plants that burn hydrogen and oxygen to produce power will become competitive, not just in terms of initial construction costs, but also in terms of yearly miming costs and longevity, with their dirty and deadly emissions rivals in that market.
This zero emissions boiler is a different kind of power plant boiler system. First off, it burns two cryogenic fuels, liquid hydrogen and liquid oxygen, pumped to burners at its base by high-pressure multi-stage cryogenic fuel pumps at high pressure, to produce the steam. The fuels are lit by high-powered sparking systems between each pair of fuel injectors which can automatically deploy repeatedly if for some reason the flame from those injectors dies out. The fuels themselves are atomized by the injector heads to make mixing and ignition easier, but at the massive volumes required by modern power plants.
This process produces both high temperatures and high pressures. Liquid hydrogen and liquid oxygen burn with a fairly hot flame and can create as much steam pressure as the boiler walls and fuel injection pressure will allow. Modern steam turbines operate over a range of pressures, from around 1000 psi all the way up to around 4500 psi. This boiler design can work at any pressure in that range and can go all the way up to the maximum if the boiler walls and fuel pumps are built to handle the high tensile stress and pressure.
While the burners are in the middle of the boiler, at the bottom, and are placed some distance from the outside wall, with continuous use the radiant and convective heat from the flame will eventually create issues in that wall. There are, at this time, two different methods of cooling the boiler to prevent issues. The first, and more expensive method, is to increase the percentage of oxygen in the mix, which will cool the flame and shorten its length. The second one, envisioned as the everyday method in this instance, is pumping water, pre-heated to about 205-210 degrees F., at extremely high pressure into the boiler through a fairly wide ring of nozzles set in between the flame and the wall. The water, aimed at the walls and at the top of the boiler, will keep those walls cooled down to a temperature that will obviate thermal expansion and creep issues, and will also cool down the steam to a planned 1000-1150 degrees Fahrenheit, the so-called “dry steam” employed by modern steam turbines to lower corrosion and wear and tear on their blades and rotors. The cooling water, turning to steam itself at that temperature, will itself create even more steam pressure in the boiler.
Once the desired steam pressure and temperature have been achieved, the valve to the steam header at the top of the boiler will open up and supply steam to the turbine, causing its rotors and shaft to spin and turn the generator rotor, creating electrical current for the power plant. The design is planned to be practically self-regulating, with pump speeds continually adjusted by the plant control center to achieve the best possible steam temperature and pressure and optimal turbine rotor speeds.
This boiler design can accommodate either no steam re-heat, single steam re-heat, or double steam re-heat systems, depending on the turbine types used in the plant and the desires of the customer. The drawings submitted show a single steam re-heat system. It can work with a wide range of steam turbines, from about 20 megawatts (a small boiler) all the way up to about 1200 megawatts (the size of boiler shown in the submitted drawings). It can produce up to and above 10 million pounds of steam per hour. It can work as a single unit or as part of a large multi-unit power plant. It can be run as a stand-alone unit, powered by a dedicated heat exchanger in the water pre-heat system, or as part of a combined cycle plant, in which the water pre-heat system is powered by the hot exhaust from a combustion turbine sent through a heat exchanger system. The pre-heat system can also use passes through the boiler in pipes, in part, as shown in the submitted drawings, powered by water pumps. This system is also designed to be practically self-regulating and controlled by the power plant control room.
The water used to supply the cooling system is produced in a condenser (not shown in the drawings) at the far end of the generator and supplies cooling ponds (not shown in the drawings) adjacent to the boiler. These are not a part of this patent application and their design is a discretionary one for the customers.
The cryogenic fuel tanks include the main tanks (not shown in the drawings) and holding tanks (not shown in the drawings), hopefully equipped with pressure relief valves, cryogenic valves, booster pumps, cooling systems, boil-off re-liquefaction systems, phase control systems, and purging systems, but the size and style of these tanks is a discretionary one, based on customer design, the size of the turbines and plants, cost, fuel supplies, and other considerations, and they are not a part of this patent application.
The high-pressure water pumps shown in the drawings are based on a reciprocating five-cylinder design of GD Energy Products capable of producing up to 20,000 psi, and only their layout, not their design, is a part of this patent application.
The high-pressure cryogenic fuel pumps shown in the drawings will have to be a custom multi-stage design built to handle cryogenic fuels and the particular issues involved with pumping liquid hydrogen at these pressures. However, many successful high-pressure liquid oxygen and liquid hydrogen pumps have been designed in the past and there are companies that specialize in jobs like that. Their actual design, including lubrication design, stage design, and electrical motor design, are a bit below the scale of this patent submission and await further refinement, but their arrangement, shown in the drawings, is a part of this patent application.
The design of the high pressure fuel injectors and their sparking systems are also a bit below the scale of this patent submission, but their arrangement, shown in the cutaway perspective section drawing, is definitely a part of this patent application. The same goes for the outer rings of water nozzles shown in that drawing, their arrangement is definitely part of this patent application, but their design is a bit below its present scale and await further refinement.
The boiler pass-through piping of the water pre-heat and re-heat systems is shown in the drawings, but these are optional features in this design and up to the customers. The pre-heat pass-through pipes can be located at either the top or the bottom of the boiler, depending upon customer preference.
The cylindrical boiler wall and hemispherical roof design shown in the drawings are definitely a part of this patent application. This is a double-wall boiler, with the inner wall designed to handle all of the pressure inside the boiler and the outer wall with a thinner section, perforated for air cooling, designed to reinforce the inner wall and close up the gaps to prevent pressure leaks. The walls are designed in sections, joined by nuts, bolts, gaskets, O-rings, and sealants. The inner wall sections have large flanges for use in those connections and for reinforcement. The material of the inner wall will have to be able to handle a very wide range of temperatures and pressures, rust issues, oxidation issues, and hydrogen embrittlement issues and will probably end up being a high-strength nickel alloy of some kind. The outer wall may be a high-strength nickel or stainless steel alloy. These walls will technically be designed for a life of around 40 years or so without failure and so creep and repeated expansion and contraction will be critical issues in their design. The boiler may have to be periodically shut down for inspection, maintenance, and cleaning.
The steam header shown is a relatively standard design in modern power plants. There are no foreseeable variations in this design. The connections to the steam turbine vary with turbine design and are therefore not a part of this patent application.
This zero emissions boiler is designed to work in conjunction with a modern power plant control room and its display, monitoring, and actuating systems. These control rooms are designed by companies that specialize in that trade and the control room layout is not a part of this patent application, The sensors and actuators in this boiler are run through dedicated signal conditions, microprocessors, and digital interfaces that allow them to function in coordination with the plant control room.
There are many aspects of this boiler design that are controlled automatically, and many that may be subject to manual control at times. The temperature and pressure in the main fuel tanks and fuel holding tanks are designed as an automatic process, with feedback loops from the sensors controlling the cooling and re-liquefaction systems in those tanks. This is particularly important for the liquid hydrogen, which has to be contained within a very specific temperature and pressure range, and in a very specific phase, in order to lessen multi-phase flow, slush, cavitation, and dangerous vaporization in the lines and pumps. This issue becomes less important at higher pressures after it reaches the main fuel pumps, however. In addition, this system will be augmented by manual control overrides and mechanical pressure relief valves.
The water pre-heat system will also be controlled automatically, with temperature and pressure sensors working in feedback loops in conjunction with the heat exchanger and the water pumps, and will also be equipped with manual overrides where possible. The feedback loops controlling the pumps will also include strain gauges placed in the boiler walls. The two systems, including the main fuel pumps and the water pumps, will also have a feedback system that includes boiler temperature and pressure gauges and data from the turbine and generator related to their speed and power output. The fuel sparking system will also be automatic, adjusted by temperature, pressure, and flow sensors in the fuel lines and burners. The system will also be equipped with manual overrides and sensor, actuator, valve, and pump failure monitoring and protection.
So that is the sense in which this is being designed as an automatic system. Today sophisticated digital control systems can make adjustments in actuators hundreds of times per minute, and actually per second in some cases. They are just a lot faster and more accurate than human reactions, as a rule, and thus can save utility companies a lot of money and prevent excessive down time. However, they do fail occasionally, thus the need for manual overrides and some mechanical back-up and safety features.
There are certain safety issues in this design, including excessive pressure and flow blockages in the tanks, pipes, valves, and pumps, excessive pressure and temperature in the boiler and turbine, and hydrogen and oxygen leakage, that have to be addressed by safety features like mechanical pressure relief valves, emergency shut-downs, and hydrogen and oxygen monitoring equipment, but these things have all been done before successfully.
The inventor, James H. Carrow, has two other patent applications pending at this time, U.S. Utility patent application Ser. No. 17/027,068 and U.S. Utility patent application Ser. No. 17/093,042. Neither one conflicts with this application in any way; they are for totally different designs.
