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    公开号:BE1020808A3
    申请号:E201300731
    申请日:2013-10-29
    公开日:2014-05-06
    发明作者:Mark Adriaensens
    申请人:Mission E；
    IPC主号:
    专利说明:

    Improved waste recycling
    SCOPE OF THE INVENTION
    The present invention relates to the recycling of waste streams into energy. More in particular, the invention relates to the conversion of chlorine-containing waste streams to electric power.
    BACKGROUND OF THE INVENTION
    Most waste streams in society in general, as well as many waste streams in the industry, contain chlorine. Conversion of such waste streams to gases at high temperatures above 450 ° C leads to the presence of chlorine in the gases produced, usually in the form of hydrogen chloride (HCl).
    This causes problems in heat recovery from those gases because HCI causes corrosion on contact with most metals when the temperature of the metal surface is in the range of 450-500 ° C. These corrosion problems are discussed in detail by WFM Hesseling and P.L.F. Rademakers in the TNO MEP R-2003 report, "Efficiency Increase or Waste-to-Energy Plants, Evaluation of Expiry with Boiler Corrosion and Corrosion Reduction", March 2003.
    (Waste streams are preferably recycled as much as possible in the same or in a lower grade application as raw materials. This becomes more difficult, if not impossible, when the waste stream is of poor quality. Separation techniques may possibly upgrade certain parts of a mixed waste stream, but their Organic waste, or organic parts of waste streams, can then be digested, ie converted into flammable gases with the help of bacteria, which can be used for energy recovery, such as gas-driven power stations, which is usually left over from mixed waste streams, such as municipal solid waste or municipal solid waste (MSW) is a non-digestible stream of solids that is still at least partially combustible.
    Λ
    Such waste streams can be referred to as refused derived fuel (refused derived fuel or RDF). They contain a significant amount of energy, and their recovery as useful energy, as in electrical energy, is considered the most appropriate way to get rid of these waste streams.
    Energy recovery from waste streams is typically based on the combustion of the waste stream and the generation of pressurized steam using the combustion heat. The steam is then used to drive a turbine, which then drives an electric power generator.
    Heat is then preferably extracted from the incineration zone by evaporating boiler feed water under pressure in steel tubes. By only partially evaporating the water stream, the temperature of the liquid in the tubes remains at the level of the boiling temperature of water at this specific pressure and remains substantially constant. The temperature of the steel of the tubes, in particular the surface temperatures of the steel tubes, will be slightly higher than the boiling temperature of the water, but can thus be maintained indirectly below a certain critical limit.
    The mixture of water and saturated steam in the tubes is led to a steam drum, the steam vapor being separated from the liquid water and withdrawn under pressure control on the steam drum.
    With the steam drum provided above the combustion zone, the hot water can flow through loops of tubes, and the difference in density between the water in the downflowing tubes, also called "the downcomers" and the steam / water mixture in the upward flowing tubes, also referred to as the "risers", where they are exposed to the heat of the combustion zone, also referred to as the radiant section of the furnace or furnace, is usually capable of driving rapid circulation through the loops without any need for pumping, so that the evaporation still partially remains at the outlet of the risers and the temperature inside the pipes remains under control.
    The tubes of the radiation section can include what are called membrane walls, usually vertical tubes arranged as a web that enclose the seat of the fire. The downcomers and risers can be used to form the membrane wall, and typically the gap between the pipes is sealed with metal strips welded to the pipes.
    The temperature limitations of the construction materials determine the maximum surface temperatures that are permitted for the risers, or for the metal strips between the tubes of the membrane wall, and therefore also the temperature that is allowed inside the risers or tubes, and therefore indirectly the maximum pressure permitted in the steam drum.
    A higher steam pressure means a more efficient steam turbine, and therefore a higher total energy recovery. The pressure in the design of the steam system will therefore usually be set as high as possible, as limited by the prevailing technical and economic limitations.
    The higher pressures of the steam also require a higher purity of the feed water from the boiler, in order to control the build-up of deposits as a result of salt precipitation in the boiling water system. The preparation of the feed water boiler therefore becomes increasingly expensive, both in terms of investment costs and operational costs, with higher steam pressures.
    Because the quality of the fuel during the solid waste incineration is neither well controlled nor constant, the combustion air supply to the combustion zone cannot be meticulously adjusted to always correspond to the energy in the fuel supply, and therefore the air-fuel ratio cannot be closely monitored. The combustion therefore typically proceeds with a significant average air excess, which moreover means that the combustion temperatures are considerably lower compared to the combustion of conventional fuels. Consequently, the temperature in the combustion chamber is limited, but it is also prone to vary both in time and in location. The same also applies to the surface temperatures of the steel pipes in which the steam is generated. Due to these variations, a significant safety margin must be taken into account when setting the design pressure of the steam system.
    Waste incineration plants, in particular those intended for the conversion of municipal solid waste, are therefore usually designed for generating steam with a pressure of a maximum of 70 bar overpressure (70 barg). This steam pressure avoids the need for super high quality boiler feed water, which usually requires additional water purification steps in addition to the steps that are usually provided. This pressure also means that the steam is generated in the. risers at its saturation temperature of approximately 287 ° C, which is therefore also the maximum temperature of the saturated steam leaving the steam drum. This pressure level ensures that the surface temperature of the risers is limited to a maximum of approximately 330 ° C, so that the corrosion effects described above are avoided or at least controlled to an acceptable level.
    Steam turbines are preferably not operated on saturated steam. Due to the expansion of the steam in the turbine, the temperature also drops, and the steam partly condenses. This condensation occurs in the form of small water droplets that hit the turbine blades at high fluid velocities and can cause erosion. More water droplets are formed within the turbine as the steam expands further towards the steam outlet of the turbine. The condensation of steam within the turbine must be kept limited due to this erosion, which endangers the integrity of the very expensive turbine blades and therefore the useful life of the turbine. A turbine can tolerate some condensation, but this is usually limited to about 4% by weight at the point where the steam leaves the turbine at the low pressure end.
    When only saturated steam is available to drive the turbine, this limitation of the amount of condensation water imposes a serious limitation on the liquid conditions inside the turbine, by limiting the pressure drop that can be allowed over the turbine from steam supply to steam outlet. However, it is the inlet-to-outlet pressure ratio that determines the amount of flow that the turbine can extract from the steam. The rest of the energy remains in the steam leaving the turbine, and is usually lost downstream where the steam is condensed for recovery as liquid condensate. With a tight limit on the permitted pressure drop across the turbine, the power output of the turbine is limited and the overall energy recovery of the power plant is considerably reduced.
    Power stations, which are based on solid waste incineration and which operate on the basis of saturated steam generation alone, have been built and put into use. The surface temperatures of the pipes in these power stations are kept below the critical range of 400-450 ° C to avoid the high corrosion rates caused by HCl and these power stations operate at a relatively low energy efficiency, with an efficiency of electrical power compared to the available combustion energy in the range of only only 20-22%. Their return on capital is limited due to various reasons. In addition to the aforementioned limitation of the surface temperature, firstly, the temperatures of the flue gases must be kept above the condensation temperature to prevent condensation. The condensate of the flue gasses from a municipal waste-to-electric power (municipal-waste-to-power or MWP) plant is known as being very aggressive. Secondly, a reduced pressure is not allowed at the turbine outlet, because of the limit imposed on the amount of condensation in the steam outlet of the turbine. Working outside these limits would quickly reduce the service life of the construction materials. It would seriously reduce the availability of the power plant and increase its maintenance costs beyond what is economically feasible, in light of the current value obtained for the disposal of the waste (the "waste fees") and the value obtained for the generated electrical electricity (energy prices, kWh rates).
    The second limitation, with respect to the turbine outlet pressure, can optionally be displaced by superheating or superheating of the steam supplied to the turbine. With superheated steam at the inlet of the turbine, the steam that expands as it travels through the turbine remains dry for a substantial part of its trajectory, and can only dive into the two-phase zone towards the end of the turbine, even when the pressure and therefore also the temperature at the steam outlet are considerably lower than with saturated steam at the inlet. With superheated steam, the inlet-to-outlet pressure ratio of the turbine can thus be increased considerably without having to increase the inlet pressure, which means that a significantly higher part of the energy from the high-pressure steam can be converted into turbine power and hence into electric power . Superheating of the steam can therefore considerably increase the overall efficiency of the power plant.
    Superheating of the steam during waste incineration, however, is not easy to achieve. The steam leaving the steam drum has a characteristic temperature of at most 287 ° C and a pressure of 70 barg. This steam should be super heated, at that high pressure, which increases the temperature, preferably as much as possible. This means that the surface temperature of the high pressure tubes of such a steam super heater also increase.
    Providing a steam super heater in the combustion zone is less preferred compared to in the downstream convection zone, because the combustion temperatures in the combustion zone are higher and not properly controlled. The flue gas temperature when burning municipal solid waste or RDF, namely the temperature of the combustion gases leaving the combustion zone, is typically still as high as 800 ° C, but significantly lower compared to a typical 1000 ° C with conventional fuels that are burned with a good and well-controlled air-fuel ratio. The reasons for these lower temperatures are described in detail above and are mainly caused by the poor fuel quality of the solid waste streams.
    Even with a co-current heat exchanger, which yields lower metal temperatures compared to a counter-current heat exchanger, and which would be designed to take the saturated steam at 287 ° C to heat it against flue gases cooling from 800 ° C, the critical surface temperatures become of 450-500 ° C is easily achieved once the steam itself has temperatures in the range of 400-450 ° C. achieved.
    The temperature of the superheated steam is therefore considerably limited because chlorine is present in the fuel and the corrosion that this can cause on the tubes of the superheater. This temperature limitation imposes a considerable limitation on the energy efficiency of a power plant that works on the basis of chlorine-containing waste materials as fuel. This limit is not present at power stations based on fuels that contain no or hardly any chlorine or other halogens. Such power stations usually achieve a much higher efficiency, which can be as high as 55%.
    With chlorine-containing fuels, however, if the superheater (s) in the convection section of the oven, and the membrane walls that may be present in the radiation section of the oven are not protected, and these temperature limits are not respected, their service life is very short, going from a few weeks to a maximum of a few months. The only industrially acceptable protection to date is an inconel steel covering, which means that the life of the equipment can be extended to one or two years. However, this represents a significant increase in investment costs, which is rarely affordable in most current economic conditions in which these power stations must operate.
    Thus, there remains a need for a method for the energetic recycling of chlorine-containing fuels, such as rejected derived fuel obtained from the separation of solid municipal waste, with higher energy efficiencies or energy yields, compared to what is known and available in the state of the technology.
    M.A. Korobitsyn et al., “Possibilities for gas turbine and waste incinerator integration”, Energy 24 (1999) 783-793, proposes to combine a solid waste incineration plant with a conventional gas-fired “steam and gas” (“STEG” or in the English version "STAG") power plant, even more widely known as "a combined cycle gas turbine" (CCGT), which is currently the most preferred way to generate electrical energy from natural gas or synthesis gas from coal to generate. The gas is fired in a gas turbine, the mechanical energy of which is converted into electrical energy. The exhaust gases from the turbine are hot, and can be used to generate steam, preferably by an additional combustion of gas in the steam generation zone. The steam can be super heated by the heat from the flue gases, which have a low chlorine content. The superheated steam is then used to drive a steam turbine, which can for example be a two-stage turbine with intermediate superheating to further improve the efficiency. The mechanical power of the steam turbine is then also converted into electrical current. The proposed combination is characterized by the fact that the solid waste incineration plant produces only saturated steam, but is superheated against the hot flue gases of the CCGT plant, which have a low chlorine content and do not cause the same corrosion problems. It is claimed that this combination of a combustion process for chlorine-containing waste with a conventional CCGT process achieves energy efficiencies that are considerably higher than those with the two processes separately. The advantage of this combination is that the chlorine-based corrosion problem is alleviated. The disadvantage is that the CCGT process still requires an important external supply of fuel, such as natural gas or synthesis gas, and that must have a low chlorine content.
    Plasma gasification is a process, already applied on a commercial scale, for converting all kinds of organic material into synthesis gas (syngas) using plasma processing. The technique uses an electric arc gasifier, also called a plasma torch, to convert a gas such as steam, air or nitrogen into a high temperature ionized gas at 2,200-13,900 ° C, and which is used to remove organic material mainly break in the form of syngas and solid waste (slag) in a controlled vessel, called the plasma converter. Its main commercial use is as waste treatment technology because it allows the complete decomposition and degradation of organic components. The slag is inert and can be granulated and used in construction. The lack or lack of oxygen and the high temperatures in the plasma reactor prevent the most important elements of the gas from forming toxic compounds, such as furans, dioxins, NOx, or sulfur dioxide. Extensive filtration removes the inorganic residue (ash) from the gas and gaseous contaminants (NO, HCl, H2S, etc.) and enables the production of ecologically clean synthesis gas. The gaseous compounds do not contain phenols or complex and heavy hydrocarbons. The dry purified syngas can thus be used as a clean fuel. The water circulating through the filter systems has removed the hazardous substances and must be cleaned. The method is intended to be a net electricity supplier, depending on the composition of the input waste, and to reduce the quantities of waste that still have to be transported to landfills.
    KR 10-2005-0102958 describes such an integrated system that combines waste plasma gasification with electrical energy generation. Solid municipal waste with a calorific value of 1500 kcal / kg is fed to the plasma gasification step. The high temperature plasma torch (2000-7000 ° C) converts the organic substances in the waste into a synthesis gas with a calorific value of 2510 kcal / m3. The non-combustible inorganic material is converted into an inert slag, which is described as useful as a building material. The synthesis gas is cooled and purified before it is used as fuel for a combined cycle power generation, i.e. in a STEG plant, where the synthesis gas is burned in a gas turbine driving a first generator, and the residual heat from the gas turbine is used to steam generating a steam turbine that drives a second generator. The process described in KR 10-2005-0102958 does not use the heat in the synthesis gas from the plasma gasification step.
    WO 03/066779 is concerned with the greenhouse effect and describes the plasma gasification of waste, wherein carbon dioxide recovered from chimney effluents from cement plants and / or coal-fired power stations is used as the inert gas for the plasma torch as well as the atomic carbon / oxygen ratio and further control the temperature in the gasification reactor. The syngas leaving the plasma gasification reactor is cooled to 1200 ° C (1473 ° K) by injecting additional carbon dioxide before the heat is used to generate steam. A second injection of carbon dioxide may be needed to further reduce the temperature to a lower level, more compatible with the presence of HCl. The syngas leaving the steam generator, at a temperature of 500 ° K (227 ° C), is contacted with sodium bicarbonate powder to form a solid mixture of sodium chloride, sodium sulfate and sodium carbonate, which can be recovered and can probably be used as raw material in the chemical industry. The steam from the steam generator drives a steam turbine, which drives a current generator. Exhaust steam from the steam turbine is used to dry the waste feed to the plasma gasifier to 10% water, before it is condensed and reused as condensate for the steam generator. The purified syngas produced can have many applications, one being fuel in a CCGT plant ("installation Turbine-Gaz-Vapeur"), to be burned in the presence of pure O 2 obtained by air permeation. The only link of the plasma gasification process with the CCGT plant is the supply of purified synthesis gas. The disadvantage of the process according to WO 03 / 066,779 is that the hot synthesis gas, against which the steam for the turbine is generated, contains chlorine. Because of the chlorine, the temperature in the steam generator must remain limited, resulting in a limited efficiency of the turbine driven by the steam.
    Thus, there remains a need for the conversion of chlorine-containing waste into electric power with a higher efficiency or yield, without needing a large external source of low-chlorine fuel.
    It is an object of the present invention to prevent or at least alleviate the problem described above and / or offer improvements in general.
    SUMMARY OF THE INVENTION
    According to the invention there is provided a method for power generation as defined in any of the appended claims
    The present invention provides a method or process for generating electrical energy from a chlorine-containing combustible stream, comprising the steps of (a) the plasma gasification of the chlorine-containing combustible stream to generate a hot chlorine-containing synthesis gas, (b) generating high pressure steam by using the heat of the hot chlorine-containing synthesis gas from step (a), (c) removing a significant portion of the chlorine from the chlorine-containing synthesis gas from step (b) to produce a low-chlorine synthesis gas, ( d) using the low-chlorine synthesis gas from step (c) as a fuel for a gas turbine of which at least part of the mechanical energy is converted into electrical energy in a first power generator, (e) using the heat from the hot gas exhaust gas from the gas turbine in step (d) to further increase the temperature of the high pressure steam of step (b) in a superheating step and (f) feeding the superheated steam of step (e) to a steam turbine of which at least a portion of the mechanical energy is converted into electrical energy in a second current generator.
    We have found that the process according to the present invention brings the advantage of a higher total energy efficiency, i.e. a higher yield of electrical energy output from the same amount of combustible energy input. While the total yield of the process does not necessarily reach the level of a single CCGT plant running on a pure and low chlorine fuel, it can nevertheless reach a higher level than the processes currently known in the art for converting a chlorine -containing flammable current in electrical energy. The applicants believe that this is due to the extra superheating that occurs in step (e) and thus the higher temperatures of the high-pressure steam that is generated from the heat in the chlorine-containing synthesis gas.
    The process according to the present invention brings the further advantage that it is less dependent, preferably not dependent at all, on an external supply of a low chlorine fuel as a supply to the gas turbine.
    The method according to the present invention brings the further advantage that it can easily respond to fluctuations in the electrical load, i.e. to fluctuations in the demand for electrical current. The chlorine-containing combustible stream is typically a stream that can be stored in storage or inventory management. The feed rate of the chlorine-containing combustible stream can therefore easily be changed to increase or decrease the stream output of the overall process, so that it can more closely meet the demand for electricity or respond to changes in power requirements. This is a great advantage, because on the one hand any surplus energy, which must necessarily be generated for process reasons, has to be sold at a relatively low value or even dissipated at a zero value, while on the other hand the extra power that occasionally from an external source must be scarce and requires a relatively high value.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Figure 1 shows a flow chart of an embodiment of the method according to the present invention.
    DETAILED DESCRIPTION
    The present invention will be described below in certain embodiments and with reference to certain drawings, but the invention is not limited thereto, but only by the claims. The drawings are only schematic and not restrictive. In the drawings, some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions, also relatively, in the drawings therefore do not necessarily correspond to how the invention is put into practice.
    In addition, the terms, first, second, third, and the like, are used in the description and in the claims to distinguish between similar elements and not necessarily to describe a sequential or chronological order. These terms are interchangeable under appropriate conditions and the embodiments of the invention may occur in sequences other than those described and illustrated herein.
    In addition, the terms top, bottom, over, under, and the like in the description and in the claims are used for descriptive purposes and not necessarily to indicate relative positions. These terms thus used are interchangeable under appropriate conditions and the embodiments of the invention may occur in sequences other than those described and illustrated herein.
    The term "include," as used in the claims, is not to be construed as limiting the elements listed in context therewith. It does not exclude that other elements or steps occur. It is to be considered as prescribing the presence of the specified characteristics, numbers, steps or parts as prescribed, but does not exclude the presence or addition of one or more other characteristics, numbers, steps or parts, or groups thereof. Thus, the scope of "an article comprising means A and B" should not be limited to an article consisting solely of means A and B. It is to say that A and B are the only elements of interest to the article in connection with the present invention to be.
    In the context of the present invention, high pressure steam is defined as steam at a pressure in the range of 48-130 bar gauge (barg), preferably at least 50 barg, more preferably at least 60 barg, even more preferably at least 65 barg and even more preferably at least 68 barg. A higher pressure of the steam brings the advantage of a higher irilate pressure available to the turbine, which is favorable for the amount of mechanical energy that the turbine is able to supply to the high-pressure steam. to withdraw. The high-pressure steam can have a pressure of at most 120 barg, preferably at most 110 barg, more preferably at most 100 barg, even more preferably at most 90 barg, even more preferably at most 80 barg, preferably at most 70 barg. A lower pressure brings the advantage that the quality requirements of the feed water of the boiler used for steam generation are reduced. A lower pressure also brings the advantage that the boiling temperature during steam generation is lower, such that the temperatures of the metal, in particular the surface temperature of the equipment used in the generation of the high pressure steam, are limited, which is favorable for the lifetime of the equipment.
    In the context of the present invention, synthesis gas, or syngas for short, is defined as a gas that contains significant amounts of hydrogen and carbon monoxide, and that is characterized by significant heat of combustion. The synthesis gas may further contain other gaseous components, such as carbon dioxide and / or water vapor. The synthesis gas may further also contain combustible components, such as hydrocarbons.
    In the context of the present invention, the chlorine-containing synthesis gas contains at least 15 volume ppm of chlorine, expressed as hydrogen chloride (HCl), preferably at least 20 ppm by weight, more preferably at least 30 ppm, even more preferably at least 40 ppm and even more preferably at least 50 volume ppm. In the context of the present invention, the chlorine content of a low chlorine synthesis gas is less than 15 ppm, on the same basis, preferably at most 10 ppm, more preferably at most 7 ppm, even more preferably at most 4 ppm, and even more preferably at most 2.0 ppm. Most preferably, the chlorine content of the low chlorine synthesis gas is less than 1.0 ppm.
    The chlorine content of a synthesis gas can be determined using techniques known in the art. The chlorine content of a synthesis gas is preferably determined by a method based on the principle of laser spectroscopy, which is usually much simpler than the older extraction methods and which has the advantage that the measurement can also be carried out in-situ or in-line. Suitable devices are available, for example, from the company Ankersmid M & C (the Netherlands). This method also has a very low detection limit, typically about 0.05 ppm volume of HCl. A further advantage is that the same principle can be used to measure sulfur, expressed as H2S, with the same advantages and a detection limit of approximately 3 ppm volume of H2S. Another suitable method for analyzing both sulfur and H 2 S is by UV absorption, such as with the Hydrogen Sulfide Analyzer OMA-300-H 2 S available from Applied Analytics, which can also be applied in-situ or in-line.
    In an embodiment of the present invention, the chlorine-containing combustible stream is a waste stream.
    In another embodiment of the present invention, the chlorine-containing combustible stream is a solid waste stream, preferably a solid municipal waste (MSW) or an industrial waste stream. Suitable industrial waste streams are contaminated wood, tires, car fluff or the like. A particularly suitable waste stream is a refused derived fuel ("refused derived fuel" or RDF) stream that is derived from a solid waste stream, such as a fixed municipal waste stream.
    The chlorine-containing synthesis gas, or syngas for short, that is generated by the plasma gasification step can have a temperature of at least 700 ° C, preferably at least 800 ° C, more preferably at least 900 ° C, even more preferably at least 950 ° C, even more preferably at least 10 0 ° C. Typically, the temperature of this syngas is no more than 1800 ° C, preferably no more than 1500 ° C, more preferably no more than 1200 ° C. The lower temperatures bring the advantage that a more conventional refractory material can be used in the construction of the plasma chamber and / or of the connection to the downstream convection section where the high pressure steam is generated according to step b) of the method according to the present invention.
    In an embodiment of the method according to the present invention, the high pressure steam of step (b) is saturated. This brings the advantage that the surface temperature of the metal of the equipment in step (b) containing the high-pressure steam can be well controlled and kept below critical levels, so that, for example, the negative effects that chlorine and / or other halogens can have on the construction materials at too high temperatures, avoided or illuminated, as explained above.
    In an embodiment of the method according to the present invention, the temperature of the high pressure steam from step (b) is at most 300 ° C and optionally at least 200 ° C. By keeping this steam at a temperature of at most 300 ° C, the surface temperature of the metal of the equipment containing the high pressure steam of step (b) can be well controlled and kept below the critical level to avoid the negative effects prevent or control chlorine and / or other halogen atoms at an acceptable level.
    In an embodiment of the method according to the present invention, the plasma gasification step (a) is a single-stage or a two-stage gasification step. In a single-stage plasma gasification step, the fuel is directly exposed to the plasma torch, and the gasification takes place within the plasma reactor. In the two-stage plasma gasification, the organic starting material is supplied to a gasification chamber where it is thermally decomposed with the heat generated by the combustion of the recycled synthesis gas and with insufficient primary air to support a complete ignition. The gas from the gasification chamber is then supplied to the plasma reactor. The gasification chamber itself can be preceded by a drying chamber, in which water can be evaporated from the starting material and recovered as steam. The single stage plasma gasification is more limited in terms of the quality of waste fuels that it can process, but produces a better quality of syngas, that is, with a higher calorific value. The two-stage process is more versatile in terms of fuel quality, but require a higher throughput to be economically responsible. The two-stage process is preferred for solid urban waste, organic waste, or streams obtained therefrom.
    In one embodiment, the method of the present invention further comprises a step (g), wherein heat from the hot gas from the gas turbine is used in step (d) to generate a second stream of high pressure steam. More heat may be available in the gas turbine exhaust gases than can be used in step (e), and / or the exhaust gases may be cooled further than is desirable or possible in step (e). It is therefore preferable to use this extra available heat to increase the useful energy output obtained by the method of the present invention.
    In the step (g) embodiment, the high pressure steam of step (g) is preferably fed to a steam turbine at least part of the mechanical energy of which is converted into electrical energy. This brings the advantage that the power output is further increased by the method of the present invention.
    In one embodiment of the method according to the present invention, the temperature of the high pressure steam from step (g) is further raised by superheating before it is supplied to the steam turbine. This brings the advantage that more of the energy in the high pressure steam of step (g) can be converted into mechanical energy output of the steam turbine, while at the same time the possible erosion of condensing steam particles in the steam turbine remains set at an acceptable level.
    In an embodiment of the method according to the present invention, the high pressure steam of step (g) is combined with the high pressure steam of step (b) before it is supplied to the same steam turbine. This brings the advantage that only one steam turbine must be provided, which reduces the complexity of the operation of the installation and the investment costs for the equipment.
    In one embodiment of the method according to the present invention, the high pressure steam of step (g) is super heated together with the high pressure steam of step (b) in the same super heater. This brings the advantage that only one steam superheater must be provided, whereby the complexity of the operation of the installation as well as the investment costs for the equipment are reduced.
    In an embodiment of the method according to the present invention, the surface temperatures of the metal in high pressure steam generator of step (b) and / or step (g), if present, are at most 450 ° C, preferably at most 430 ° C even more preferably at most 425 ° C, even more preferably at most 420 ° C, preferably at most 415 ° C, more preferably at most 410 ° C, even more preferably at most 405 ° C, most preferably at most 400 ° C, and optionally at least 350 ° C, preferably at least 375 ° C, preferably at least 390 ° C, even more preferably at least 400 ° C, even more preferably at least at least 410 ° C, and preferably at least 420 ° C. The surface temperatures of the metal of the tubes in furnaces can easily be measured by techniques known in the art. We prefer to use contact thermocouples based on the Seebeck effect, certain types of which are commercially available to be able to measure temperatures up to 800 ° C and even up to 1100 ° C. Suitable thermocouples are available from the Fabritius company (Belgium).
    In an embodiment of the method according to the present invention, the superheated steam of step (e) has a temperature of at least 290 ° C, preferably at least 300 ° C, more preferably at least 350 ° C, even more preferably at least 400 ° C, even more preferably at least 450 ° C, preferably at least 500 ° Q, more preferably at least 550 ° C and even more preferably at least 570 ° C. These higher steam temperatures bring the advantage that a larger portion of the energy contained in the steam can be recovered by the steam turbine of step (f), while at the same time the possible erosion by condensing steam particles in the steam turbine remains set at an acceptable level.
    In an embodiment of the method according to the present invention, surface temperature of the metal in the steam superheater of step (e) is at least 400 ° C, preferably at least 420 ° C, more preferably at least 440 ° C, at still more preferably at least 460 ° C, even more preferably at least 480 ° C, preferably at least 500 ° C, more preferably at least 520 ° C, even more preferably at least 540 ° C, even more preferably at least 560 ° C, and optionally no more than 650 ° C, preferably at most 630 ° C, more preferably at most 610 ° C, even more preferably at most 580 ° C, even more preferably at most 560 ° C. It is a great advantage of the present invention that the steam superheater of the process of the present invention is exposed to gases from the combustion of fuel that has a sufficiently low chlorine content, or does not contain chlorine or other halogens at levels where it is a concern for chlorine corrosion of metals at high temperatures.
    In an embodiment of the method according to the present invention, the gas turbine of step (d) and the steam turbine of step (f) drive the same common power generator. Such a so-called "single shaft" operation brings the advantage of a lower total investment cost, reduces operational complexity, reduces the footprint needed for the equipment and reduces the start-up costs for the process.
    In another embodiment of the method according to the present invention, the gas turbine of step (d) and the steam turbine of step (f) drive a different power generator. Such a so-called "multishaft" operation brings the advantage of higher operational flexibility, higher reliability. In a preferred embodiment, two gas turbines are provided, the second gas turbine of which can be kept as a reserve for when the first gas turbine requires an intervention, such as maintenance.
    In the embodiment of the method according to the present invention, the synthesis gas is burned in the gas turbine with air as an oxygen carrier and / or with an oxygen-containing gas that is richer in oxygen than ordinary air.
    In the embodiment of the method according to the present invention, the gas turbine exhaust gases in step (d) have a temperature in the range of 400-600 ° C, preferably at least 420 ° C, more preferably at least 440 ° C and optionally at most 560 ° C, preferably at most 540 ° C and more preferably at most 520 ° C.
    In an embodiment of the method according to the present invention, the hot exhaust gases from the gas turbine are heated in step (d), preferably with co-firing, more preferably by the combustion of low-chlorine synthesis gas from step (c) and / or by use the excess oxygen present in the hot exhaust gases from the gas turbine, before the heat from the exhaust gases is used in step (e). The additional heating of the gas turbine exhaust gases offers the advantage that the overall energy efficiency of the process is increased, in particular when the equipment is running at partial load. The additional heating step also provides a very easy additional control option to respond to fluctuations in energy requirements. The additional heating can bring the temperature of the hot gas from the gas turbine to a level in the range of 600-900 ° C, preferably at least 650 ° C, more preferably at least 700 ° C, even more preferably at least 750 ° C.
    In an embodiment of the method according to the present invention, the steam turbine of step (f) has at least two stages and at least a portion of the outlet steam of the higher pressure turbine stage is further heated before it is used to lower the lower pressure turbine stage to drive.
    In an embodiment of the method according to the present invention, the low pressure outlet of the steam turbine is at a pressure of at most atmospheric pressure, preferably at most 0.7 bar absolute (bara), more preferably at most 0.5 bara even more preferably at most 0.4 bara, even more preferably at most 0.3 bara. The lower outlet pressure allows the turbine to extract a larger portion of the energy present in the high pressure steam as mechanical energy, which improves the overall energy output for the same energy input.
    In one embodiment of the method of the present invention, the steam turbine outlet steam is condensed to form a condensate that is at least partially recycled to the high pressure steam generation in step (b) and / or the high pressure steam generation in step (g) if present, the condensate is preferably degassed and vented before it is recycled to the high pressure steam generation, the degassing or venting is preferably performed by injection of low pressure steam, the condensate preferably being preheated in an economizer before being recycled to the high pressure steam in step (e) or the upstream venting step, if any. The condensation of the low pressure turbine exhaust stream allows the turbine outlet pressure to be controlled by means of a vacuum pump, which is much more environmentally friendly than by means of steam jets. The condensation step also allows at least partial recovery of the condensate and recycling it as boiler feed water for the steps of the process or process producing steam, so that less fresh boiler feed water is required, which requires chemicals and produces chemical waste. The heat from the condensation of the steam turbine low pressure outlet stream is preferably used to dry the chlorine-containing combustible stream, or is used for something else, such as heating an aquaculture, or for district heating. In one embodiment, this heat is released to the environment, preferably by condensing the water vapor in an air cooler.
    In one embodiment of the process of the present invention, the chlorine-containing synthesis gas from step (b) is cooled before the chlorine removal in step (c). The preferred temperature for the chlorine removal step depends on the chosen system. Those skilled in the art will easily find the preferred synthesis gas temperature as the entry temperature for the selected chlorine removal step.
    In one embodiment of the method according to the present invention, the chlorine in step (c) is removed by passing the synthesis gas through a system selected from a wet wash system, a half wet wash system, a flash drying system, a dry adsorption system, and combinations thereof. In a wet washing system, the gas is supplied to a water, hydrogen peroxide solution and / or a washing liquid containing a reagent, such as, for example, a sodium hydroxide solution. The reaction product is aqueous. A wet wash system typically consists of a first wet gas washer at low pH to remove primarily HCl, and also HF, if present. If desired, it can be followed by a second wet gas washer at high pH of 6-8 mainly for the removal of SO 2. Three or more stages can also be used, the first low pH stage being subdivided into additional stages for specific purposes. The wet wash system usually brings the advantage of the highest removal efficiency of soluble acid gases such as HCl, but also HF and SO 2, compared to its possible alternatives. They offer the possibility of treating these gases without solid particles, which are often and preferably removed upstream, if present. A further advantage is that the plasma step hardly produces any dioxins. The typical risk for dioxin accumulation in wet washers is therefore advantageously low.
    In a semi-wet wash system, also referred to as semi-dry, a sorbent is added to the gas in an aqueous solution (e.g., lime milk) or suspension (e.g., as a slurry). The water solution evaporates and the reaction products are dry. The residue can be recycled to improve reagent use. A subset of this technique are the so-called flash drying systems that consist of the injection of water, which gives rapid gas cooling and a reagent at a filter inlet.
    In a dry adsorption system, a dry sorbent such as lime or sodium bicarbonate is added to the gas stream. The reaction product is dry.
    If necessary, the synthesis gas can also be dedusted, upstream or downstream of the chlorine removal step, or between different stages of the chlorine removal step, if present. Dust removal can be performed using equipment selected from cyclones and / or multi-cyclones, electrostatic precipitators (ESP), bag filters, and combinations thereof.
    Gas polishing steps may be performed, in place of or in addition to dedusting steps, through the use of one or more bag filters, wet ESP, electrodynamic venturi washers, agglo filter modules, ionizing wet washers, and combinations thereof. Double bag filters are also used, not necessarily directly next to each other.
    For the removal of acid gas components such as HCl, HF and / or SOx, a variety of basic reagents can be used, such as sodium hydroxide or potassium hydroxide, lime, limestone, sodium bicarbonate, and combinations thereof.
    In order to deal with varying concentrations of HCl, but also HF and / or SOx, a gas polishing system can be added in which the remaining traces of the upstream HCl removal step can be removed. A wet system is preferably selected for such an additional polishing system.
    In one embodiment of the method according to the present invention, also most sulfur, if present, is removed from the chlorine-containing synthesis gas before the gas is fed to the gas turbine. Preferably, the synthesis gas fed as fuel for the gas turbine has a sulfur content, expressed as H 2 S, of at most 1000 ppm volume, preferably at most 500 ppm volume, more preferably at most 200 ppm volume, even more preferably at most 100 volume ppm and even more preferably at most 50 ppm volume. Applicants have found that the preferential chlorine removal steps also contribute to the reduction of the sulfur content of the treated synthesis gas, if sulfur is present.
    In an embodiment of the method according to the present invention, the water concentration of the synthesis gas fed as fuel to the gas turbine is also set such that the syngas is "dry" at ambient temperature, i.e., no water condenses when the gas is cooled to a temperature of 25 ° C, preferably only 15 ° C, more preferably only 10 ° C, and even more preferably only 0 ° C. A suitable method for removing excess water is to cool the wet synthesis gas so that the water is condensed and can be removed by simple phase separation and withdrawn. Such condensation can be carried out in a stainless steel cooler. To remove excessively corrosive components upstream of this cooler, a wet gas wash step may be included before the cooling step.
    In an embodiment of the method according to the present invention, the synthesis gas fed as fuel for the gas turbine is brought to a temperature of 55 ° C. In the event that the gas is to be heated to 55 ° C, a suitable way is to recycle a portion of the compressed syngas from the compressor outlet to the compressor inlet via a simple bypass.
    In one embodiment, the method according to the present invention is for generating electrical energy during a period of increased power consumption, preferably a period of peak demand for current. It has been described above that the method according to the present invention is, for various reasons, particularly suitable for responding to fluctuations in demand, an important reason being that an inventory of the feed stream of the method can easily be maintained, which can be consumed at a variable speed that is adjusted to a change in demand, such as during a period from peak demand to power.
    The plasma gasification in step (a) can be performed using methods known in the art. Suitable methods can be found, for example, in WO 03 / 066,779 or KR 10-2005-0102958. The plasma gasification step uses an electric arc gasifier, also known as a plasma torch, to form a high temperature ionized gas that degrades organic material in the feed stream into synthesis gas. Most of the inorganic matter in the feed stream is usually found as solid waste or slag.
    EXAMPLES
    The present invention is now further illustrated with the flow chart shown in Figure 1. Chlorine-containing combustible stream 1 is supplied to plasma gasification step 100, where the hot chlorine-containing synthesis gas 2 is generated. The hot chlorine-containing synthesis gas 2 is supplied to a first steam boiler 101, where the heat from the gas is used to convert the boiler feed water 15 into typically saturated high-pressure steam 11. The cooled chlorine-containing synthesis gas from steam boiler 101 is supplied to a wet syngas scavenging step 102. The partially cleaned synthesis gas 4 from this wet cleaning step passes through a stainless steel cooler / condenser 103 to remove a large portion of the water from the stream 4. The cooled and partially dewatered chlorine-containing synthesis gas 5 from the cooler / condenser 103 is supplied to the dry syngas clean-up step 104. In the combination of the wet syngas clean-up step 102, the cooler / condenser 103 and the dry clean-up step 104, a substantial part of the chlorine removed from the chlorine-containing synthesis gas to produce the low chlorine synthesis gas 6. This low chlorine synthesis gas 6 is then compressed in syngas compressor 105.
    The compressed synthesis gas 7 is then used as fuel in gas turbine 106, at least part of the mechanical energy of which is converted into electrical energy in a first generator (not shown). The combustion in the gas turbine 106 produces hot exhaust gases 8. The hot exhaust gases 8 are fed to a steam superyer heater 107 where part of the sensible heat of the hot exhaust gases is used to superheat the substantially saturated steam that is used in the first and second steam boilers 101 and 108 is produced, wherein a partially cooled stream of exhaust gas 9 is produced. The partially cooled exhaust gas 9 is fed to the second steam boiler 108, in which further heat is removed from the partially cooled exhaust gases 9 to convert boiler feed water stream 16 into substantially saturated high pressure steam 17. The further cooled exhaust gas 10 can be discharged, for example as a flue gas to the atmosphere. The superheated steam 12 from superheater 107 is used to drive steam turbine 200, at least a portion of the mechanical energy of which is converted to electrical energy in a second generator (not shown). The low pressure exhaust steam 13 from the turbine is fed to condenser 201, and generates condensate 14, which is fed to degasser 202. The degassed water from degasser 202 is pumped through a high pressure boiler feed water pump (not shown) as stream 15 to the first steam boiler 101 and as stream 16 to the second steam boiler 108.
    权利要求:
    Claims (27)
    [1]
    A method for generating electrical energy from a chlorine-containing combustible stream, comprising the steps of (a) the plasma gasification of the chlorine-containing combustible stream to generate a hot chlorine-containing synthesis gas, (b) generating high-pressure steam by the use heat from the hot chlorine-containing synthesis gas from step (a), (c) removing a substantial portion of the chlorine from the chlorine-containing synthesis gas from step (b) to produce a low chlorine content of synthesis gas, (d) using the low-chlorine synthesis gas from step (c) as a fuel for a gas turbine of which at least part of the mechanical energy is converted into electrical energy in a first power generator, (e) using the heat from the hot exhaust gases from the gas turbine in step (d) to further increase the temperature of the high pressure steam of step (b) in a superheating step, and (f) feeding the supervery heat steam from step (e) to a steam turbine of which at least a part of the mechanical energy is converted into electrical energy in a second current generator.
    [2]
    The method of claim 1, wherein the chlorine-containing combustible stream is a waste stream.
    [3]
    The method according to claim 1 or 2, wherein the chlorine-containing combustible stream is a solid waste stream, preferably a fixed urban waste stream (MSW) or an industrial waste stream, preferably a refused derivative fuel stream (RDF) derived from a solid waste stream, such as a fixed municipal waste stream.
    [4]
    The method according to any of the preceding claims, wherein the high pressure steam of step (b) is saturated.
    [5]
    The method of any one of the preceding claims wherein the high pressure steam temperature of step (b) is at most 300 ° C and optionally at least 200 ° C.
    [6]
    The method of any one of the preceding claims, wherein the plasma gasification step (a) is a single-stage or a two-stage gasification step.
    [7]
    The method of any one of the preceding claims, wherein the chlorine-containing combustible stream contains at least 5 volume ppm of chlorine, expressed as hydrogen chloride (HCl).
    [8]
    The method according to any of the preceding claims, further comprising a step (g), wherein the heat from the hot gas from the gas turbine is used in step (d) to generate a second stream of high pressure steam.
    [9]
    The method according to claim 8, wherein the high pressure steam of step (g) is supplied to a steam turbine of which at least a part of the mechanical energy is converted into electrical energy.
    [10]
    The method of claim 9, wherein the temperature of the high pressure steam from step (g) is further increased by superheating before it is supplied to the steam turbine.
    [11]
    The method of claim 10, wherein the high pressure steam of step (g) is combined with the high pressure steam of step (b) before it is supplied to the same steam turbine.
    [12]
    The method of claim 11, wherein the high pressure steam of step (g) is super heated together with the high pressure steam of step (b) in the same super heater.
    [13]
    The method according to any of the preceding claims, wherein the surface temperatures of the metal ("metal skin temperature") in the high pressure steam generator of step (b) and / or step (g), if present, are at most 450 ° C and optionally at least 350 ° C.
    [14]
    The method of any one of the preceding claims, wherein the superheated steam of step (e) has a temperature of at least 290 ° C.
    [15]
    The method of any one of the preceding claims wherein the surface temperatures of the metal in the steam superheater of step (e) are at least 400 ° C, and optionally no more than 655 ° C.
    [16]
    The method of any one of the preceding claims, wherein the gas turbine of step (d) and the steam turbine of step (f) drive the same common power generator.
    [17]
    The method of any one of claims 1-15, wherein the gas turbine of step (d) and the steam turbine of step (f) drive a different power generator.
    [18]
    The method according to any of the preceding claims, wherein the synthesis gas is burned in the gas turbine with air as an oxygen carrier and / or with an oxygen-containing gas richer in oxygen than regular air.
    [19]
    The method of any one of the preceding claims, wherein the gas turbine exhaust gases in step (d) have a temperature in the range of 400-600 ° C.
    [20]
    The method according to any of the preceding claims, wherein the hot exhaust gases from the gas turbine are heated in step (d), preferably with co-firing, more preferably by burning low-chlorine synthesis gas from step (c) and / or by using the excess oxygen present in the hot exhaust gases from the gas turbine, before the heat from the exhaust gases is used in step (e).
    [21]
    The method of any one of the preceding claims, wherein the steam turbine of step (f) has at least two stages and at least a portion of the outlet steam of the higher pressure turbine stage is further heated before being used to lower the lower pressure turbine stage to drive.
    [22]
    The method according to any of the preceding claims wherein the lowest pressure is exhaust from the steam turbine at a pressure of at most atmospheric pressure, preferably at most 0.7 bar absolute (bara).
    [23]
    The method of any one of the preceding claims wherein the steam turbine outlet steam is condensed to form a condensate that is at least partially recycled to the high pressure steam generation in step (b) and / or the high pressure steam generation in step (e).
    [24]
    The method of any one of the preceding claims, wherein the chlorine-containing synthesis gas from step (b) is cooled before the chlorine removal in step (c).
    [25]
    The method of any one of the preceding claims, wherein the chlorine in step (c) is removed by passing the synthesis gas through a system selected from a wet wash system, a half wet wash system, a flash drying system, a dry adsorption system, and combinations thereof.
    [26]
    The method of any one of the preceding claims, wherein the low chlorine synthesis gas used in step (d) contains less than 5 ppm of chlorine expressed as hydrogen chloride (HCl).
    [27]
    The method according to any of the preceding claims for generating electrical energy during a period of increased power consumption, preferably a period of peak demand for current.
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    同族专利:
    公开号 | 公开日
    WO2014067588A1|2014-05-08|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP1375628A3|2000-01-21|2004-12-08|Integrated Environmental Technologies, Llc.|Methods and apparatus for treating waste|
    WO2003066779A1|2002-02-06|2003-08-14|Absil Felicien|Gazeification de dechets par plasma|
    AU2002368399A1|2002-11-25|2004-06-18|David Systems Technology, S.L.|Integrated plasma-frequency induction process for waste treatment, resource recovery and apparatus for realizing same|
    WO2004112447A2|2003-06-11|2004-12-23|Nuvotec, Inc.|Inductively coupled plasma/partial oxidation reformation of carbonaceous compounds to produce fuel for energy production|
    KR20050102958A|2004-04-23|2005-10-27|한국전력공사|Integrated waste gasification combined cycle system|
    RU2007146272A|2005-06-03|2009-06-20|Пласко Энерджи Групп Инк., |SYSTEM FOR PROCESSING COAL IN GAS OF A SPECIFIC COMPOSITION|
    法律状态:
    2020-08-13| MM| Lapsed because of non-payment of the annual fee|Effective date: 20191031 |
    优先权:
    申请号 | 申请日 | 专利标题
    PCT/EP2012/071813|WO2014067588A1|2012-11-05|2012-11-05|Method for the generation of electric power from a chlorine-containing combustible stream|
    EP2012071813|2012-11-05|
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