Methods for separating pollutants from a flue gas stream

Abstract

A method for separating pollutants from a pollutant-containing flue gas stream, wherein the pollutant-containing flue gas stream is cooled to a flue gas inlet temperature of no more than -10°C and the cooled, pollutant-containing flue gas stream is passed through an adsorption reactor (101) which contains a carbon-containing adsorption material, wherein at least nitrogen oxides (NOx) and sulfur oxides (SOx) are removed from the flue gas stream by adsorption on the adsorption material, characterized in that the flue gas stream is passed into the adsorption reactor (101) with the addition of ammonia.

Description

[0001] The present invention relates to a method for separating pollutants from a flue gas stream. State of the art

[0002] The use of fossil or organic fuels in industrial processes and thermal power plants produces flue gases. These flue gases contain various types of pollutants, especially nitrogen oxides (NOx), sulfur oxides (SOx), and the greenhouse gas carbon dioxide (CO2).

[0003] Various methods for removing pollutants from flue gases are known in the prior art. These methods differ both in their effectiveness, i.e., the proportion of pollutants removed, and in their efficiency, i.e., the amount of reagents and / or energy required for flue gas separation.

[0004] Flue gas desulfurization, i.e., the removal of sulfur oxides, requires large amounts of water and energy.

[0005] To remove nitrogen oxides, processes such as selective catalytic reduction (SCR) or non-selective catalytic reduction (NSCR) are used. These processes require catalytic materials, which are expensive and whose production in turn requires large amounts of energy and scarce raw materials.

[0006] Furthermore, flue gases typically contain a certain amount of water vapor, or process steam is required for flue gas treatment. This water vapor usually escapes into the atmosphere, which is detrimental in times of water scarcity.

[0007] Another problem with the use of fossil fuels is the production of carbon dioxide. Carbon dioxide acts as a greenhouse gas in the atmosphere and contributes significantly to global warming. Therefore, industrial processes and electricity generation aim to at least reduce the resulting carbon dioxide emissions.

[0008] The state of the art describes various approaches to improve individual aspects of flue gas treatment.

[0009] In DE 11 2018 005 746 B4 a system is described in which, in addition to dust particles and gaseous oxides, carbon dioxide can also be removed from the flue gas.

[0010] DE 43 09 460 A1 describes a method for reducing nitrogen oxides using a multi-stage drastic process.

[0011] From DE 10 2009 013 691 A1 a method for the combined exhaust gas treatment of exhaust gas streams containing ammonia and nitrogen oxides is known.

[0012] EP 0 974 388 A1 relates to a method for cleaning gases from industrial processes using moistened activated carbon, wherein the gas stream is also moistened.

[0013] From DE 36 16 501 A1 a process for cleaning flue gases is known, in which carbon-containing catalysts are used.

[0014] In DE 36 03 447 A1 a two-stage process for the separation of pollutants from flue gases is described, in which in a second stage some of the pollutants are separated on activated carbon or activated coke, which are then burned after separation has taken place.

[0015] DE 34 23 744 A1 relates to a process for separating sulfur dioxide and nitrogen oxides from flue gases, wherein the total flue gas stream is divided into a main stream and a partial stream. The majority of the sulfur dioxide and a smaller proportion of nitrogen oxides are separated from the main stream in a wet scrubbing process with the addition of calcium hydroxide or calcium carbonate.

[0016] DE 20 2021 101 207 U1 discloses an integrated adsorption desulfurization denitrification system in which flue gas is introduced into a low-temperature moving bed adsorption tower and flows through an adsorber as a cross-flow.

[0017] US 2019 / 0 105 596 A1 discloses a process for separating pollutants from a flue gas stream, in which the flue gas stream is cooled to +30-50°C and directed into an adsorption reactor with a carbon-containing adsorbent.

[0018] In WO 2011 / 111 116 A1, the separation of CO2 from a flue gas stream cleaned of NOx and SOx by means of adsorption is mentioned.

[0019] Further relevant state of the art can be found in AT 389652 B.

[0020] In view of increasing resource scarcity, air pollution, water shortages and the emission of climate-damaging greenhouse gases, it is necessary to create optimized and efficient methods for flue gas treatment. DESCRIPTION OF THE INVENTION

[0021] The object of the invention is to create an improved method for separating pollutants from a flue gas stream.

[0022] The problem is solved by a method with the features of claim 1. In the inventive method for separating pollutants from a pollutant-containing flue gas stream, the pollutant-containing flue gas stream is cooled to a flue gas inlet temperature of no more than -10°C and the cooled, pollutant-containing flue gas stream is passed through an adsorption reactor which contains a carbon-containing adsorption material, wherein at least nitrogen oxides and sulfur oxides are removed from the flue gas stream by adsorption on the adsorption material and wherein the flue gas stream is passed into the adsorption reactor with the addition of ammonia.

[0023] The pollutants that may be present in the contaminated flue gas stream include, in particular, nitrogen oxides (NOx), sulfur oxides (SOx), and carbon dioxide (CO2). The adsorption reactor is preferably a flow-through reactor, meaning that the flue gas is introduced into the adsorption reactor and, after at least partial adsorption of pollutants, is discharged. A partially purified flue gas stream emerges from the adsorption reactor, from which NOx and SOx have been largely or completely removed, but which still contains CO2 as a further pollutant. Activated carbon, preferably produced from biological material, especially biological waste material, or activated coke can be used as the adsorption material. The flue gas inlet temperature is preferably no more than -15°C, and particularly preferably no more than -20°C. The flue gas stream is advantageously dehumidified before or during cooling.During adsorption, the flue gases may warm up slightly (e.g. from -20°C to -18°C).

[0024] The inventive method enables the efficient cleaning of flue gas streams, which arise particularly in facilities operated with fossil or organic fuels and / or additives, for example in thermal power plants including combined heat and power plants such as cogeneration units (CHP plants), steelworks including blast furnaces, direct reduced iron (DRI) plants, electric arc furnaces, pelletizing plants and other facilities, cement plants, ceramic plants, petrochemical plants, biomass plants or biogas plants. It has been shown that the adsorption capacity of activated carbon or comparable materials increases with decreasing temperature.The process according to the invention is based on the surprising finding that this property can be used to remove at least nitrogen oxides and sulfur oxides from the pollutant-containing flue gas stream by means of a physical process without the use of chemical substances, provided the flue gas stream is cooled to no more than -10°C. The process according to the invention has proven superior to conventional processes in terms of both effectiveness and efficiency. In particular, when the required activated carbon is obtained from biological materials, especially from biological waste, the process according to the invention is characterized by high environmental friendliness due to its low resource requirements.

[0025] According to the invention, the flue gas stream is fed into the adsorption reactor with the addition of ammonia. Ammonia is preferably added to the flue gas stream before it enters the adsorption reactor, generally after cooling, but alternatively also before. The ammonia is at least partially adsorbed by the adsorption material; a certain portion of the NOx can react with the ammonia in the adsorption reactor to form water (H₂O) and nitrogen (N₂). In principle, the addition of ammonia is not necessary to effect the actual separation of nitrogen oxides from the pollutant-containing flue gas stream. However, it has been shown that, according to the invention, adding ammonia during the adsorption process simplifies the subsequent elimination of the separated nitrogen oxides.

[0026] Preferably, the amount of ammonia added is controlled based on a measured concentration of nitrogen oxides in the flue gas stream. A stoichiometric ratio between the amount of ammonia introduced and the amount of nitrogen oxides in the flue gas stream is targeted, in each case per unit volume, mass, or amount of substance. This reduces ammonia slip and minimizes the risk of incomplete reduction of nitrogen oxides.

[0027] According to a further preferred embodiment of the process, the loaded adsorption material is transferred from the adsorption reactor to a first regeneration reactor. The adsorbed substances are desorbed from the adsorption material by introducing superheated steam into the first regeneration reactor, and the discharged adsorption material is transferred from the first regeneration reactor to the adsorption reactor. This part of the process is also referred to as thermal alternating adsorption. The desorbed nitrogen oxides are reduced to nitrogen and water vapor by the also desorbed ammonia. The desorbed sulfur oxides and the water vapor—that is, both the supplied water vapor and the water vapor produced during the reduction of the nitrogen oxides—react to form sulfuric acid, which can be removed and further utilized.The discharged adsorption material is preferably cooled before being transferred from the first regeneration reactor to the adsorption reactor. This creates a cycle of loaded and discharged adsorption material between the reactors, whereby the circulation of the adsorption material can be continuous or discontinuous.

[0028] The desorption temperature, generated by the steam and at which desorption takes place, is preferably 400 to 450°C. The first regeneration reactor is heated to the desorption temperature by the superheated steam; that is, the temperature of the superheated steam must be at least equal to the desorption temperature.

[0029] Preferably, exhaust steam discharged from the first regeneration reactor is fed to a turbine to generate electrical energy. This increases energy efficiency. Preferably, this exhaust steam can be mixed with further superheated steam from a heat recovery system of a first heat transfer unit, described below. The superheated steam from the first heat transfer unit can then become the main energy source for power generation.

[0030] According to a further preferred embodiment of the process, the cooling of the pollutant-containing flue gas stream takes place, at least in an intermediate step, by means of a first heat transfer device, which transfers heat from the pollutant-containing flue gas stream to a fluid stream, preferably feeding the fluid stream into a turbine to generate electrical energy. The aforementioned first heat transfer device, as well as any further heat transfer devices mentioned subsequently, can be referred to as a heat recovery device and may, for example, be designed as a heat exchanger. The cooling process can also be carried out in multiple stages, e.g., by means of a series of several heat transfer devices.

[0031] The fluid flow can be, in particular, a flow of water or steam, or a flow of another suitable heat transfer medium, wherein the fluid preferably transitions from the liquid phase to the gas phase through heat transfer and is condensed after performing the work. The turbine is preferably a steam turbine, and particularly preferably a condensing turbine, which is optimized for operation at relatively low fluid temperatures.

[0032] If the flue gas temperature is relatively low, the heat from the pollutant-containing flue gas stream can, for example, be supplied to a so-called "Organic Rankine Cycle" (abbreviation ORC), in which the fluid serving as the heat transfer medium for a turbine is an organic liquid with a low evaporation temperature.

[0033] According to a further preferred embodiment of the process, the cooling of the pollutant-containing flue gas stream is carried out, at least in an intermediate step, by means of a second heat transfer device, which transfers heat from the pollutant-containing flue gas stream to ambient air. Thus, air cooling is provided, which, by further reducing the temperature, dissipates heat that can no longer be used efficiently in order to increase the energy efficiency of subsequent cooling steps. Advantageously, the second heat transfer device is arranged in the flue gas stream downstream of the first heat transfer device.

[0034] The first and / or second heat transfer device can, for example, reduce the flue gas temperature from more than 120°C, especially more than 200°C, to approximately 60°C.

[0035] According to a further preferred embodiment of the process, the cooling of the contaminated flue gas stream is carried out, at least in an intermediate step, by means of a third heat transfer device, which transfers cold from the flue gas stream discharged from the adsorption reactor to the incoming contaminated flue gas stream. This allows, for example, a further cooling of the incoming contaminated flue gas stream from approximately 60°C to 5°C. The partially cleaned flue gas stream discharged from the adsorption reactor, which typically exits at -18°C, is thereby heated, for example, to approximately 20 to 25°C. This heat exchange contributes to lower cooling energy consumption. This makes the cooling of the flue gas stream more energy-efficient. Preferably, the third heat transfer device is arranged in the flue gas stream downstream of the second heat transfer device.

[0036] According to a further preferred embodiment of the method, the pollutant-containing flue gas stream is cooled to the flue gas inlet temperature by means of a compression chiller which has a refrigerant circuit in which refrigerant circulates, which is alternately compressed and expanded, wherein the refrigerant circuit is coupled to the flue gas stream by means of a fourth heat transfer device.

[0037] In principle, other types of refrigeration machines can also be used. Carbon dioxide or nitrogen are preferably used as refrigerants. Carbon dioxide and nitrogen can be cooled to -25°C at low pressure with less energy than other refrigerants and are harmless and safe substances with regard to health and the environment. Preferably, the fourth heat transfer device is arranged in the flue gas stream downstream of the third heat transfer device.

[0038] Preferably, expansion is achieved using an expansion turbine, which generates electrical energy from the energy contained in the refrigerant. The electrical energy generated during the expansion process is preferably used to operate electrically driven units required for the process, such as pumps, compressors, or fans. This results in a higher efficiency, known as the coefficient of performance (COP), compared to conventional compression refrigeration systems. The COP ranges from 1.5 to 1.7.

[0039] Preferably, the four cooling steps described above are combined using the first to fourth heat transfer devices. This minimizes the external energy required for cooling, which is primarily supplied by the refrigeration unit, while simultaneously making the majority of the thermal energy contained in the flue gas stream usable.

[0040] According to a further preferred embodiment of the process, at least a partial flow of the pollutant-containing flue gas stream is passed through a heat storage unit. The heat storage unit can compensate for temperature fluctuations in the flue gas stream that may occur during the process of flue gas generation and ensures that the secondary processes supplied with heat by the flue gas stream can continue to operate without interruption and without the need for temporary input of additional externally generated heat, even in the event of a temporary temperature drop in the flue gas stream.

[0041] According to a further preferred embodiment of the process, the flue gas stream discharged from the adsorption reactor is passed through a carbon dioxide separator containing a carbon dioxide-binding separating substance, whereby carbon dioxide is removed from the flue gas stream by absorption in the separating substance. Calcium carbonate or sodium carbonate, for example, can be used as the carbon dioxide-binding separating substance.

[0042] According to a further preferred embodiment of the process, additionally heated water and / or steam is introduced into the carbon dioxide separator. When calcium carbonate or sodium carbonate is used as the separating agent, absorption occurs through conversion to calcium or sodium bicarbonate, respectively, upon the addition of water or steam. The temperatures and quantities of the introduced water or steam are advantageously selected such that the process temperature prevailing in the carbon dioxide separator is between 60 and 80°C.

[0043] Preferably, the loaded residue is transferred from the carbon dioxide separator to a second regeneration reactor. The absorbed carbon dioxide is desorbed from the residue by introducing superheated steam into the second regeneration reactor, and the discharged residue is transferred from the second regeneration reactor to the carbon dioxide separator. The hydrogen carbonate is thereby converted back into the corresponding carbonate. The introduced steam serves to maintain the required process temperature in the second regeneration reactor, which is preferably approximately 120°C. Thus, a cycle of loaded and discharged residue is created between the carbon dioxide separator and the second regeneration reactor, which can be operated continuously or discontinuously.

[0044] Preferably, desorbed carbon dioxide extracted from the second regeneration reactor is converted into methanol with the addition of hydrogen and energy. The required energy is preferably supplied in the form of electricity generated from renewable energy sources. Alternatively, the carbon dioxide can also be used or stored in other ways.

[0045] According to a further preferred embodiment of the process, residual water generated during at least one process step is recovered, collected, and / or treated by condensation and / or separation, and at least partially made available in the form of process water or steam for carrying out the aforementioned process step and / or at least one further process step. The residual water can be collected and temporarily stored in a common container or reused directly in the relevant subprocess. The treatment includes, in particular, mechanical and / or chemical purification steps such as filtration and neutralization.

[0046] Preferably, the residual water is recovered from the adsorption reactor, the carbon dioxide separator, the first and / or second regeneration reactor, and / or during the cooling of the pollutant-containing flue gas stream in the third heat transfer unit. This residual water can be reused in the process, but can also be used for other purposes, such as being fed into an industrial process or used as process or drinking water.

[0047] According to a further preferred embodiment of the method, the refrigerant circuit includes a fifth heat transfer device through which compressed refrigerant flows, transferring heat contained in the compressed refrigerant to recovered residual water. The excess waste heat generated during refrigerant compression can thus be used to preheat the residual water for subsequent steam generation, thereby reducing the energy required for this steam generation.

[0048] According to a further preferred embodiment of the process, steam, in particular superheated steam, which is required for carrying out at least one process step, and electrical energy, which is used in particular for operating electrically driven units used to carry out the process, are generated by means of a combined heat and power (CHP) plant. Steam is generated from the waste heat of the CHP plant's exhaust gases, whereby the flue gas temperature usable for steam generation can typically reach up to 600°C. This allows the heat requirement for adsorption, absorption, and desorption processes to be covered, at least to a significant extent. The electricity generated by the CHP plant can cover at least a significant portion, or even all, of the electrical energy required for carrying out the process according to the invention.Any surplus electricity that may arise can be fed into the public electricity grid.

[0049] Preferably, the steam generated by the combined heat and power plant, in particular superheated steam, is fed to the first and / or the second regeneration reactor and / or the carbon dioxide separator.

[0050] The exhaust gases from the combined heat and power plant are preferably mixed with the pollutant-laden flue gas stream. This also cleans the CHP exhaust gases / flue gases.

[0051] The invention further relates to a flue gas cleaning system which is set up to carry out the method according to the invention and includes at least the components mentioned in the embodiments of the method according to the invention or preferred embodiments and the lines required for the transport of the fluids and / or energy mentioned. Drawings

[0052] Further advantages become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0053] They show: Fig. 1 to 5 Piping and instrumentation diagrams of various parts of an exemplary flue gas cleaning plant, which is set up to carry out the method according to the invention, and Fig. 6. A piping and instrumentation diagram of the exemplary flue gas cleaning plant in an overview.

[0054] In the following, the same reference symbols are used for identical or similar elements.

[0055] In Fig. Figures 1 to 6 show the respective piping and instrumentation diagrams of an exemplary flue gas cleaning system designed to remove pollutants from a pollutant-laden flue gas stream. While in Fig. The diagram shows that 1 to 5 different sections of the flue gas cleaning system are depicted. Fig. 6. An overview of the flue gas cleaning system. However, not all of the [details omitted] are necessarily included. Fig. 1 to 5 components or elements shown in Fig. 6 shown and vice versa.

[0056] According to Fig. 6. The flue gas cleaning system comprises various lines 1 to 82 through which fluids, i.e., liquid or gaseous substances or mixtures of substances, as well as solids, are transported or conveyed between different components of the flue gas cleaning system, or which serve for the supply or discharge of fluids to and from components of the flue gas cleaning system. The type of fluid or solid transported through each line 1 to 82 is determined by the specific context.

[0057] The following are the respective temperatures and pressures for the transported fluids. These values ​​are purely exemplary and may deviate from the stated values ​​within process tolerances and variations that a person skilled in the art might readily foresee within the scope of this disclosure, without this being explicitly mentioned in each individual case.

[0058] Contaminated flue gas is introduced into an adsorption reactor 101 via line 31. Ammonia (NH3) is added to this flue gas stream via line 32. The amount of added NH3 can be controlled to ensure a stoichiometric ratio with respect to the amount of nitrogen oxides contained in the flue gas stream. The flue gas stream supplied via line 31 was cooled to a temperature of -20°C before being introduced into the adsorption reactor 101, as will be described in more detail below. The adsorption reactor 101 is filled with activated carbon as the adsorption material, which is preferably made from organic material, in particular organic waste material. The activated carbon absorbs at least some of the pollutants contained in the flue gas stream, especially nitrogen oxides and sulfur oxides. Some of the supplied ammonia reacts with the nitrogen oxides even before absorption.The remaining portion of the ammonia is also adsorbed by the adsorption material. The flue gas stream, partially purified by the described adsorption process, leaves the adsorption reactor 101 via line 44.

[0059] The activated carbon loaded with pollutants is conveyed via line 75 into the first regeneration reactor 111. Superheated steam at a temperature of 550°C and a pressure of 50 bar is introduced into the first regeneration reactor 111 via line 50. Additionally, water at a temperature of 40°C and a pressure of 50 bar is introduced into the first regeneration reactor 111 via line 43.

[0060] In the first regeneration reactor 111, the pollutants adsorbed on the activated carbon and the ammonia are desorbed. The nitrogen oxides are reduced to nitrogen and water by the ammonia. The water produced in this process, as well as any additional water supplied in the form of water or steam, reacts with the desorbed sulfur oxides to form sulfuric acid (H₂SO₄), which is discharged from the first regeneration reactor 111 via line 51. Exhaust steam generated in the first regeneration reactor 111 is discharged at a temperature of 400°C and a pressure of 47 bar via line 48 and at a temperature of 300°C and a pressure of 47 bar via line 47.

[0061] In the first regeneration reactor 111, further solid pollutants separated are discharged and fed to a sieve 103 and subsequently recycled.

[0062] The activated carbon, now free of pollutants, is transported back to the adsorption reactor 101 via line 76. The activated carbon thus circulates in a loop between the adsorption reactor 101 and the first regeneration reactor 111, with the circulation being either continuous or discontinuous. Lines 75 and 76 do not necessarily have to be designed as pipelines, but can also be implemented using conveyor belts or similar devices.

[0063] The superheated steam supplied via line 50 is generated by a combined heat and power (CHP) plant 102. Natural gas or hydrogen is supplied to the CHP plant 102 via line 77 and combusted with the addition of compressed air. The resulting combustion gases are fed via line 78 to a gas turbine 104, which is coupled to a generator 105. The combustion gases exiting the gas turbine 104 are fed via line 79 to a heat exchanger 126 and, after heat exchange, discharged via line 9.

[0064] Water is supplied to a pump 131 via line 40, which feeds the supplied water into the first regeneration reactor 111 via line 43 and into the heat exchanger 126 via line 57. The heat exchanger 126 uses the fuel gases exiting the gas turbine 104 to generate superheated steam from the supplied water, which is then introduced into the first regeneration reactor 111 via line 50.

[0065] According to Fig. 2. The flue gas stream to be cleaned, containing pollutants, originates, for example, in an industrial plant powered by fossil fuels, such as a steel mill or a thermal power plant, which is generally referred to here as flue gas source 108. The temperature of the flue gas stream is typically initially between 200 and 600°C.

[0066] A partial flow of the hot flue gas passes through line 3, a blower 106, and line 7 into a heat storage tank 107. The heat storage tank 107 is heated by the hot flue gas, thus compensating for temperature fluctuations in the flue gas flow. The heat storage tank 107 is coupled to a first heat transfer device 121, which in this embodiment is formed by a heat exchanger. The heat transfer device 121 extracts heat from the flue gas flow to convert water, supplied by a pump 132 via line 14, into steam. The steam is then fed via lines 15 and 16 to a condensing turbine 110 to generate electrical energy by means of a further generator 105.

[0067] Another partial flow of hot flue gases passes via line 2, a further blower 106, and line 6 to a further first heat transfer device 121, which is also designed as a heat exchanger and converts water supplied via line 12 into steam. The steam also passes via lines 13 and 16 to the condensing turbine 110.

[0068] The exhaust steam from the condensing turbine 110 passes through line 23 to a condenser 140, where it is condensed. From there, the condensate is pumped through line 24 to the pump 132.

[0069] The cooled flue gas partial streams pass via lines 20 and 21 to a mixer 109. There they are combined into a common flue gas stream, which leaves the mixer 109 via line 25 and has a temperature of approximately 95°C.

[0070] According to Fig. 3 and Fig. 4 The flue gases leaving the mixer 109 pass via line 25, another blower 106 and line 26 to a second heat transfer device 122, which is designed as a cooler and cools the flue gas stream from approximately 95°C to 60°C.

[0071] The flue gases then pass from the second heat transfer unit 122 via line 27 to a third heat transfer unit 123, which is designed as a heat exchanger. The inlet side of the third heat transfer unit 123 is connected to line 44, which supplies cold, partially cleaned flue gas from the adsorption reactor 101. Through heat exchange in the third heat transfer unit 123, the pollutant-laden flue gas is cooled from 60°C to 5°C, and simultaneously the cold, partially cleaned flue gas is heated from -18°C to approximately 20°C. The heated, partially cleaned flue gas leaves the third heat transfer unit 123 via line 45 and is conveyed further via another blower 106 and line 46.

[0072] According to Fig. 4. The flue gas, cooled to 5°C and containing pollutants, passes through line 28 to a condensate separator 142, where it is dehumidified. The separated condensate or condensed water is fed via lines 33 and 34 to a treatment unit 143, in which the condensate is physically and / or chemically purified. A portion of the treated water leaves the treatment unit 143 via line 36 and is fed to further process steps, which will be explained in more detail below. The other portion of the treated water is fed via line 80 to a collection tank 144.

[0073] The cooled, pollutant-laden flue gas stream exiting the condensate separator 142 passes via line 29, another blower 106, and line 30 to a fourth heat transfer unit 124, which is integrated into a refrigerant circuit of a chiller 146. The refrigerant circuit of the chiller 146 includes an electrically driven compressor 147, which liquefies gaseous refrigerant. The liquefied refrigerant, heated in this process, is cooled in a fifth heat transfer unit 125 and then expanded by means of an expansion turbine 148, thereby cooling it further. The significantly cooled gaseous refrigerant then enters the fourth heat transfer unit 124, where it cools the pollutant-laden flue gas from 5°C to -20 to -23°C.The flue gas, cooled to the flue gas inlet temperature in this way, passes via line 31 from the fourth heat transfer unit 124 to the adsorption reactor 101 (compare . Fig. 1).

[0074] The partial flow of condensate, which leaves the treatment unit 143 via line 36 at a temperature of 5°C, is fed via another pump 133 and line 38 to the fifth heat transfer unit 125. There, it is heated to a temperature of 40°C by the heated liquefied refrigerant. It then flows via lines 39 and 40 at a pressure of 3 bar to pump 131, which increases the pressure to 55 bar in lines 43 and 57 (see Figure 1). Fig. 1) Part of the heated condensate flows from line 39 via line 41 to collection container 144.

[0075] According to Fig. 5. The partially cleaned flue gas stream, heated to 20°C, enters (compare Fig. 4) via line 46 to a carbon dioxide separator 149, which contains a carbon dioxide-binding separating substance, for example, calcium carbonate or sodium carbonate. The carbon dioxide contained as a further pollutant in the partially cleaned flue gas stream is removed from the flue gas stream by absorption in the separating substance. Superheated steam at a temperature of 550°C and a pressure of 50 bar is additionally supplied via line 58, which branches off from line 50. The now completely cleaned flue gas stream flows from the carbon dioxide separator 149 via line 52 to a cooling tower 150 and from there into the atmosphere. Excess process water is discharged from the carbon dioxide separator 149 via line 59.

[0076] The carbon dioxide-laden separation substance is transported via line 81 from the carbon dioxide separator 149 to a second regeneration reactor 112. The separation substance is heated by introducing superheated steam via line 65, which branches off from line 50, causing the absorbed carbon dioxide to desorb from the separation substance. The desorbed carbon dioxide is then conveyed via line 53 from the second regeneration reactor 112 to a carbon dioxide utilization facility 151, where, for example, the carbon dioxide can be converted into methanol or other synthetic fuels using hydrogen and electrical energy, or liquefied or compressed for the purpose of long-term storage of the separated carbon dioxide.

[0077] The carbon dioxide-free separator substance is transported back from the second regeneration reactor 112 to the carbon dioxide separator 149 via line 82. The separator substance thus circulates in a loop between the carbon dioxide separator 149 and the second regeneration reactor 112, with the circulation being either continuous or discontinuous. Lines 81 and 82 do not necessarily have to be designed as pipelines, but can also be implemented using conveyor belts or similar devices.

[0078] The temperatures and quantities of water and steam introduced into the carbon dioxide separator 149 and the second regeneration reactor 112 are selected such that the process temperature prevailing in the carbon dioxide separator 149 is between 60 and 80°C and the process temperature prevailing in the second reaction reactor 112 is approximately 120°C.

[0079] Excess process water generated in the second regeneration reactor 112 can be discharged via line 67, a further heat exchanger 127, and line 68, or via line 63. Recovered process water can be tempered via line 70, heat exchanger 127, and line 64 and fed to the carbon dioxide separator 149.

[0080] The process water flow via lines 59, 63, 68, 69, 70 and 71 is controlled by means of a four-way valve 152, whereby an excess can be fed to the collection tank 144 via line 71.

[0081] The in Fig. The piping and flow diagram shown in Figure 6 illustrates the entire flue gas cleaning system. Compared to the individual diagrams of the... Fig. Details 1 through 5 may have been added, modified, or omitted. Some of the differences are explained in more detail below.

[0082] Unlike the one in Fig. The single flue gas source 108 shown in the 2 are in Fig. Figure 6 shows four different flue gas sources as examples: a blast furnace 161 for direct reduced iron (DRI), an electric arc furnace 162, a pelletizing plant 163, and a power plant 164. The respective flue gas streams are guided via lines 1 to 8, the several blowers 106, the several first heat transfer devices 121, and lines 19 to 22 into the mixer 109.

[0083] Water is pumped from pump 132 via line 10 to the first heat transfer devices 121, which are connected to the flue gas streams of the electric arc furnace 162, the pelletizing plant 163, and the power plant 164, flowing through them in series. The steam generated by heat exchange with the flue gases is supplied to the condensing turbine 110 via lines 13 and 16.

[0084] The exhaust steam, which is under high pressure and is discharged from the first regeneration reactor 111 via lines 47 and 48, is also fed to the condensation turbine 110 via lines 49 and 16.

[0085] Additionally, a power grid 155 is shown, which connects various electrical devices, with the arrow directions indicating the direction of energy flow. The power grid 155 transmits the electrical energy generated by the various generators 105 to the various consumers, such as the various blowers 106, the various pumps 131 to 133, and the compressor 147. Any surplus energy can be fed into the public power grid.

[0086] The flue gas cleaning process or flue gas cleaning system according to the invention provides an integrated system for the simultaneous recovery of heat, water, and pollutants such as nitrogen oxides, sulfur dioxide, and carbon dioxide. When all aspects of the invention are combined, industrial plants and power stations using fossil and organic fuels emit only nitrogen and oxygen. Other previously present pollutants are largely converted into usable substances. Water vapor present in the flue gases is condensed, so that clean water is provided after a cleaning and treatment process.Using the method according to the invention and its implementation by means of the integrated system described above, industrial plants and power stations that use coal, petroleum, natural gas, biomass, or biogas as fuel are operated in an environmentally friendly and water-resource-conserving manner with very low heat loss and reduced greenhouse gas emissions. The invention thus provides a technology that combines energy efficiency, environmental aspects, and water resource conservation. Reference symbol list 1 - 82 Line 101 Adsorption reactor 102 Combined heat and power plant 103 seven 104 Gas turbine 105 Generator 106 blowers 107 Heat storage 108 Source of flue gas 109 mixers 110 Condensation turbine 111 first regeneration reactor 112 second regeneration reactor 121 - 125 first to fifth heat transfer device 126, 127 Heat exchanger 131 - 133 Pump 140 Capacitor 142 Condensate separators 143 Processing plant 144 collection containers 145 Capacitor 146 Refrigeration machine 147 Compressor 148 Expansion turbine 149 carbon dioxide separators 150 cooling tower 151 Carbon dioxide recovery facility 152 Four-way valve 155 Power grid 161 Blast furnace - direct iron reduction DRI 162 Electric arc furnace 163 Pelletizing plant 164 Power Plant

Claims

[1] Method for separating pollutants from a pollutant-containing flue gas stream, wherein the pollutant-containing flue gas stream is cooled to a flue gas inlet temperature of not more than -10°C and the cooled, pollutant-containing flue gas stream is passed through an adsorption reactor (101) which contains a carbon-containing adsorption material, wherein at least nitrogen oxides (NOx) and sulfur oxides (SOx) are removed from the flue gas stream by adsorption onto the adsorption material, characterized by , that the flue gas stream is directed into the adsorption reactor (101) with the addition of ammonia. [2] Method according to claim 1, characterized by , that the amount of ammonia added is controlled based on a measured concentration of nitrogen oxides in the flue gas stream. [3] Method according to any one of the preceding claims, characterized by, that the loaded adsorption material is transferred from the adsorption reactor (101) to a first regeneration reactor (111), the adsorbed substances are desorbed from the adsorption material by introducing superheated steam into the first regeneration reactor (111), and the discharged adsorption material is transferred from the first regeneration reactor (111) to the adsorption reactor (101). [4] Method according to claim 3, characterized by that desorption takes place at a desorption temperature of 400 to 450°C. [5] Method according to one of claims 3 and 4, characterized by , that exhaust steam discharged from the first regeneration reactor (111) is fed to a turbine (110) to generate electrical energy. [6] Method according to any one of the preceding claims, characterized by, that the cooling of the pollutant-containing flue gas stream takes place at least in an intermediate step by means of a first heat transfer device (121) which transfers heat from the pollutant-containing flue gas stream to a fluid stream, wherein the fluid stream is preferably supplied to a turbine (110) to generate electrical energy. [7] Method according to any one of the preceding claims, characterized by , that the cooling of the pollutant-containing flue gas stream takes place at least in an intermediate step by means of a second heat transfer device (122) which transfers heat from the pollutant-containing flue gas stream to ambient air. [8] Method according to any one of the preceding claims, characterized by, that the cooling of the pollutant-containing flue gas stream takes place at least in an intermediate step by means of a third heat transfer device (123), which transfers cold from the flue gas stream discharged from the adsorption reactor (101) to the pollutant-containing flue gas stream to be introduced. [9] Method according to any one of the preceding claims, characterized by , that the cooling of the pollutant-containing flue gas stream to the flue gas inlet temperature is carried out by means of a compression chiller (146) which has a refrigerant circuit in which refrigerant circulates, which is alternately compressed and expanded, wherein the refrigerant circuit is coupled to the flue gas stream by means of a fourth heat transfer device (124). [10] Method according to claim 9, characterized by , that the expansion is carried out by means of an expansion turbine (148) which generates electrical energy from the energy contained in the refrigerant. [11] Method according to any one of the preceding claims, characterized by , that at least a partial flow of the pollutant-containing flue gas stream is passed through a heat storage unit (107). [12] Method according to any one of the preceding claims, characterized by , that the flue gas stream discharged from the adsorption reactor (101) is passed through a carbon dioxide separator (149) which contains a carbon dioxide binding separating substance, whereby carbon dioxide is removed from the flue gas stream by absorption in the separating substance. [13] Method according to claim 12, characterized by , that additionally heated water and / or water vapor is introduced into the carbon dioxide separator (149). [14] Method according to one of claims 12 and 13, characterized by, that the loaded separation substance is transferred from the carbon dioxide separator (149) to a second regeneration reactor (112), the absorbed carbon dioxide is desorbed from the separation substance by introducing superheated steam into the second regeneration reactor (112), and the discharged separation substance is transferred from the second regeneration reactor (112) to the carbon dioxide separator (149). [15] Method according to claim 14, characterized by , that desorbed carbon dioxide discharged from the second regeneration reactor (112) is converted into methanol with the addition of hydrogen and energy. [16] Method according to any one of the preceding claims, characterized by, that residual water generated during at least one respective process step is recovered, collected and / or treated by condensation and / or separation, and is made available, at least partially, for the execution of the said process step and / or at least one further process step in the form of process water or steam. [17] Method according to claim 16, characterized by , that the residual water is recovered from the adsorption reactor (101), the carbon dioxide separator, the first and / or second regeneration reactor (111, 112) and / or during the cooling of the pollutant-containing flue gas stream in the third heat recovery unit (123). [18] Method according to one of claims 9 and 10 and one of claims 16 and 17, characterized by, that the refrigerant circuit has a fifth heat transfer device (125) through which compressed refrigerant flows and transfers heat contained in the compressed refrigerant to recovered residual water. [19] Method according to any one of the preceding claims, characterized by , that water vapor, in particular superheated water vapor, which is required to carry out at least one process step, and electrical energy, which is used in particular to operate electrically operated units used to carry out the process, are generated by means of a combined heat and power plant (102). [20] Method according to claim 19, characterized by , that the steam produced by means of the combined heat and power plant (102), in particular superheated steam, is supplied to the first and / or the second regeneration reactor (111, 112) and / or the carbon dioxide separator (149). [21] Method according to one of claims 19 and 20, characterized by , that exhaust gases from the combined heat and power plant (102) are mixed with the pollutant-containing flue gas stream.

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