Acid filter for contaminant gases of thermal power station and locomotive and ship with fossil fuel

Abstract

According to the World Health Organization, 7 million people die annually due to inhaling exhaust gases containing SO2 and NOX from power plants. The majority of these emissions come from fossil fuel combustion in thermal power plants and diesel engines. Industrial development is necessary for providing electricity, but the growth in societies will lead to an increase in pollution. Existing filters are costly, discouraging power plants from using them. This invention prevents smoke from power plants, ships, and locomotives from entering the atmosphere. The process involves removing vaporized particles and converting SO2 gas into sulfuric acid, which can be used in various industries. The remaining gases, including NOX, are converted into nitric acid and other useful compounds through a series of steps. The final output contains only minimal CO gas, which can be controlled through improved oxidation methods in fuel combustion.

Description

Acid Filter for Contaminant Gases of Thermal Power Station and Locomotive and Ship with Fossil Fuel

[0001] According to the report of the World Health Organization, 7 million people die every year due to the inhalation of SO2 NOX power plant exhaust gases. Most of these gases are caused by the combustion of fossil fuels (fuel oil, oil, gas, and gas) in thermal power plants and diesel engines. On the one hand, there is no urgent need for industrial development to provide electricity for thermal power plants, and the progress and growth of societies will increase their number. Therefore, societies with the problem of the accumulation of pollutants from thermal power plants and the smoke of diesel ships and locomotives, including SO2, NOX, CO2, and suspended particles will be caused by fossil fuel combustion. On the other hand, the high cost of the existing filters has not attracted the power plants to use them because they have looked at it as an additional cost.

[0002] Pollution caused by the exhaust gases of thermal power plants and diesel engines, steamships and locomotives, and trains with fossil fuels are considered one of the most important sources of environmental pollution, which is necessary to investigate and research in the field of pollution released from them. Here, the NOx and SOx pollution caused by the combustion of thermal power plants, etc. have been described, and appropriate solutions have been presented to reduce these harmful effects. Introduction The investigation of environmental effects caused by urban, rural, and industrial development projects should be considered in the framework of studies of environmental effects and their impact on safety and health.

[0003] C07B 31 / 00 - B01D 46 / 00

[0004] GB1423916

[0005] PROCESS FOR PURIFYING GASES

[0006] H 2 S and / or HCN are removed from gases by treating them with an aqueous alkaline absorbent, e.g. an ammonia solution of a desulphurizing catalyst or an ammoniacal suspension of solid sulphur so as to form with the contaminant a compound containing nitrogen and sulphur, e.g. ammonium thiosulphate, ammonium thiocyanate, discharging the treated gas and combusting the absorbent medium containing the fixed contaminant at a temperature from 800- 1300‹ C. to produce a gaseous combustion product containing SO 2 , removing the SO 2 from the gaseous product and discharging the residual gas. The fixed contaminant may have a concentration of 5 to 80% by weight in the absorbent medium, preferably 50-70% by weight and the combustion temperature may be 1100-1200‹ C. In the apparatus ofgas is washed in absorption tower 1 with an ammoniacal suspension of S which is recycled by way of tank 3, so as to fix HCN as ammonium thiocyanate and H 2 S as ammonium thiosulphate. Fresh S suspension may be supplied from tank 4. Partially spent suspension may pass via pump 5 to filter press 6 from where solid S is returned to tank 4 and filtrate passed to tank 8. Alternatively partially spent suspension may pass directly to tank 8 from which liquid is sent to steam heater 11 via pump 9 and thereafter to concentration tower 12. Concentrated liquid is pumped into tank 16 by pump 13. Vapour from tower 12 is condensed by cooler 17 and separated in vapour liquid separator 18. Separated gas returns to absorption tower 1 and separated liquid to tank 3. Concentrated liquid from tank 16 is sprayed into furnace 22 by pump 21. At concentrations of nitrogen containing S above 70%, air is blown into furnace 22 at an initial temperature of at least 800‹ C. by blowers 23, 24 to decompose the N-containing S compound. At concentrations below 70% fuel is also supplied. Heat is recovered from the combustion products in boiler 26 and dust is removed in filter 27. Gas from filter 27 passes to reactor 28 where SO 2 is oxidized to H 2 SO 4 in condenser 30 and collected in tank 33. The acid is sent to heat exchanger 32 by pump 31 for cooling. Gases from condenser 30 may be discharged to the atmosphere or passed through washing tower 34 and Cottrell precipitator 35 before discharge through chimney 36.

[0007] The mentioned process is similar to ours but their process is not the same and it does not exclusively work as an acidic filter and convert the exhaust gas into other shapes.

[0008] United States Patent 5456891

[0009] Process for the purification of contaminated exhaust gases from incineration plants

[0010] A process, using regenerable adsorption materials, for purifying exhaust gases that have been contaminated with at least SO2, a heavy metal such as mercury and additional toxic gases such as dioxins and furans is disclosed. The process includes adsorbing the exhaust gases where the gas if freed of SO2, heavy metal and additional toxic gases, and optionally subjecting the gas from the adsorber to further treatment. The contaminated adsorber material is subjected to an oxygen-free regeneration process and the gas from the regeneration process is scrubbed and subsequently processed into pure sulfuric acid in a nitric oxide-sulphuric acid plant.

[0011] The mentioned patent is close to our claimed one but it only functions in incineration plants and ours works in ships, locomotives, and other thermal stations using fossil fuels.

[0012] CA2611872C

[0013] Waste gas treatment process including removal of mercury

[0014] A process for removing contaminants from a waste gas stream comprises treating the waste gas stream to remove at least one of SO2 and NOx and to obtain a lean stream having a reduced level of at least one of SO2 and NOx and, contacting the lean gas stream with a mercury absorbent solution comprising permanganate to remove mercury vapour and to obtain a mercury lean stream and a mercury rich absorbent solution. The mercury rich absorbent solution may be subsequently treated on a batch basis to remove precipitated manganese dioxide and obtain a solution containing mercury ions.

[0015] The mentioned invention follows a similar process as our claimed patent but it focuses more on the mercury element.

[0016] United States Patent 4600414

[0017] Apparatus for removing contaminants from heated gases

[0018] Methods of and apparatus for removing contaminants from heated gases by impact separation. The contaminants are collected by adhering them to a moving surface, and they are thereafter removed from that surface.

[0019] The mentioned patent removes contaminants but it is not an acidic filter and it also does not purify or turn them into other substances.

[0020] A device has been developed to capture pollutant gases emitted from thermal power plants, locomotives, trains, and ships with diesel engines, including SO2, NOX, CO2, and suspended particles. The captured gases are reabsorbed in the production of sulfuric acid, nitric acid, and sodium bicarbonate. The device consists of components such as a connecting pipe to the chimney outlet, a water tank for removing suspended particles, sulfuric acid and nitric acid production systems, and large tanks for sodium bicarbonate production and storage. By creating a closed system, the device prevents the release of polluting gases into the air. The gases enter the device through a connection pipe, where suspended particles are separated in the water tank. Different processes are carried out to remove specific gases and produce various compounds like sulfuric acid, nitric acid, and sodium bicarbonate. The result is the conversion of harmful gases into more environmentally friendly substances.

[0021] Considering the per capita increase in electric energy production, as well as the intensity of the energy demand for the population the electric energy demand for the population per year is equivalent to several thousand kilowatt hours. The required thermal energy will be ten times that of kilocalories, 90% of which will be obtained by burning fossil fuels, in other words, millions of tons of fuel oil are needed to provide the total annual energy production.

[0022] According to the emission factors caused by fossil fuels, which have been calculated both practically and theoretically, a large number of suspended particles, sulfur dioxide gases, nitrogen oxides, hydrocarbons, and carbon dioxide are discharged into the air of different regions of the country. Based on this, the investigation of the environmental effects of thermal power plants should be considered to investigate the situation of the installation area and identify the air pollutants caused by the chimneys of the power plants and the effects of the pollutants on the environment. Fossil fuels and climate changes Combustion of fossil fuels along with the loss of green space cover, especially forests, due to the growth of industry and the development of cities causes the increase and accumulation of carbon dioxide in the atmosphere.

[0023] The amount of carbon dioxide in the atmosphere is expected to reach 560 ppm at the end of the 21st century, and in such a case, the infrared radiation emitted from the earth will accumulate in the nearby atmosphere on the surface of the globe and cause a phenomenon called the greenhouse effect. have created and caused an increase in the temperature of the earth and finally caused the issue of climate change, which has worried environmental scientists after the review of the latest documents related to the greenhouse effect in the meeting held in October 1985 in Villach, Austria. Scientists from 29 countries concluded that climate change should be taken very seriously. This conference was held by the World Meteorological Organization and the International Council of Science They are considered pollutants and a wide range of compounds that are either caused by fuel or consumables entering the air, but mostly related to the open air.

[0024] The five major pollutants are carbon dioxide, sulfur dioxide, nitrogen oxide, suspended particles, and ozone, the first four enter the air as a result of fuel consumption or the working process of some industries, and ozone is one of the photochemical pollutants that later in Air is formed. In this case, the standards for different regions are different according to the environmental power and the acceptance capacity of the environment, but for the environments and big cities, the strictest output standards for industries should be established. On the other hand, for the circulation of the economy, a minimum should also be accepted, which can have some flexibility with the type of fuel consumed. Currently, for power plants according to their capacity, the maximum output pollutants can be as follows: SO2, 86 grams for every one million kilojoules of incoming thermal energy, suspended particles 15 grams for every one million kilojoules of incoming thermal energy, NOx, 130 to 90 grams for every one million kilojoules of heat, either gas or diesel and the average calorific value of all types of fuels.

[0025] According to the latest statistics, every year 70 billion liters of oil and 70 billion cubic meters of gas are used to produce electricity in power plants, which according to experts in the field of energy can be easily reduced by reducing technical and non-technical losses of electrical energy and saving consumption, a significant part of oil and Save gas.

[0026] In total, about 460 billion grams of SO2 / NO2 molecules enter the air we inhale every year, and by extracting it, in addition to removing this amount of pollutants from the air, it is equivalent to about 500 million liters of sulfuric acid and nitric acid produced annually in this system.

[0027] The results of the investigation of the air pollutants caused by the exhaust gases from the chimneys of power plants and the results of the calculations of the SO2 emission factor from the chimneys show that the concentration of sulfur dioxide emitted from the chimneys in normal working conditions is 17 times the standard output limit (86 g / GJ), and it will be close to the same amount in the condition of maximum load. The amount of NOx output from the power plant chimney in normal conditions is nearly 10 times the maximum allowed (135 g / GJ) and will reach 14 times at maximum load. The concentration of SO2 in the surroundings of the power plant is 1.8 to 2.5 times the 24-hour standard limit (365 micrograms per cubic meter) in all seasons of the year. The maximum concentration occurs in the summer season. In critical conditions and maximum load, the concentration of SO2 will be 1569 micrograms per cubic meter at a distance of 1340 meters from the chimneys of the power plant, and its amount will gradually decrease in the following distances.

[0028] The maximum concentration occurs in the summer season. The NOx concentration in the environment around the power plant is lower than the 24-hour limit in all seasons of the year.

[0029] And finally, the appropriate methods for removing and reducing these gases are stated:

[0030] 1- Implementation of air pollution control management

[0031] 2- Change working conditions and combustion equipment burner control system and other boiler components

[0032] 3- Optimum combustion with excess air to reduce pollutants and analyze the theory of fuel and combustion and suitable combustion models in the boiler

[0033] 4- Changing the refueling conditions or the flue gas recirculation method

[0034] 5- Using flow techniques (air and fuel mixing control)

[0035] 6- Using energy consumption optimization methods in power plantsSolution of Problem

[0036] The analysis of exhaust gases from thermal power plants and diesel engines of ships and locomotives shows the presence of three main molecules: SO2, NOX, and CO2, as well as amounts of suspended particles. Instead of releasing these pollutants into the air, the exhaust pipe is connected to a water boiler using a suction pump. In this system, the suspended particles are removed, while the remaining SO2, NOX, and CO2 are also processed and used in the production process of sulfuric acid, nitric acid, and sodium bicarbonate respectively:

[0037] First, how to produce sulfuric acid:

[0038] A) Conversion of sulfur dioxide SO2 to sulfur trioxide SO3

[0039] b) Converting sulfur trioxide SO3 into sulfuric acid HSO4

[0040] One of the most important sources of sulfur is oil and natural gas. Sulfur-containing compounds, both in the form of organic compounds and hydrogen sulfide, must be used from oil or natural gas that is to be used as power plant fuel or chemical raw materials. The gases do not enter the cylindrical tower.

[0041] In this special catalyst tower, SO2 is converted to SO3. The catalyst in this tower is vanadium pentoxide, which is located inside the tower in the form of four layers. Both layers are connected, separated only by a mesh metal plate. The amount of catalyst is different in these four layers. The fourth layer, which is the lowest layer, contains 70% of the catalyst, the rest of the layers contain 20, 7, and 3% of the catalyst. The total amount of catalyst per ton of 98% acid produced is 200 kg.

[0042] The SO2 gas produced from chimneys has a high temperature and if it enters the catalyst tower at this temperature, it will destroy the catalyst. Therefore, before entering the tower, its temperature must be reduced. For this purpose, before entering this gas into the first tower, we enter it into the steam boiler. To transfer its heat to the water in the pot, it cools down to 500 degrees Celsius. At this stage, there is the possibility of silica dust particles and elements such as lead and arsenic (possible sulfur impurities) in the combustion gas, which must be passed through a special silica filter to prevent them from entering the catalytic tower. At this level, suspended particulate pollutants and harmful to health are removed.

[0043] In this filter, in addition to trapping impurities, by injecting dry and cool air into the gas, the lack of oxygen is also removed, and the temperature reaches 450 degrees Celsius, which is a suitable temperature for entering the catalytic tower. SO2 to SO3 conversion in the heated catalytic tower is shown in the [Formula. 1].

[0044] The heat generated during this reaction damages the catalyst. To avoid this problem, SO3 gas enters the heat exchanger and cools down to 450 degrees Celsius. Also, the increase in temperature, in addition to the destruction of the catalyst, causes the heat of the aforementioned reaction to return to the production of SO2 gas.

[0045] The produced SO3 gas still contains some SO2 and must pass through the third and fourth layers of the catalyst to convert the remaining SO2 into SO3. The SO3 coming out of the fourth layer enters another heat exchanger and cools down to 240 degrees Celsius. Then it enters the oleum tower (fuming sulfuric acid) and finally enters the acid tower.

[0046] In this tower, SO3 gas and acid move in opposite directions, so that the acid moves down from the top of the tower as a spray, and the gas flows from the bottom to the top of the tower. During this process, the SO3 gas is absorbed by the acid, creating oleum or fuming sulfuric acid, which is the same acid with a high percentage of SO3. [Formula. 2] and [Formula. 3]

[0047] As can be seen, according to Charles-Gillosac's law, the heat returns to the production of SO3 gas due to the return of the reaction. To prevent this deed, the acid enters the cooling device before entering the tower to lose its temperature and reach a temperature of 50-60 degrees Celsius.

[0048] The scientific explanation of its components includes:

[0049] 1 - Gas Cleaning section: In this section, the temperature and humidity of the gas are adjusted and all pollutants and suspended particles are separated from the existing polluting gases.

[0050] 2 - Contact section: In this section, gases containing SO2, which have been cleaned in the previous section, are first converted into sulfur trioxide during a catalytic reaction.

[0051] 3 - Absorption part: then it turns into sulfuric acid during the reaction in the acid tower. To convert SO2 gas to SO3, there is the following equipment.

[0052] Contact section:

[0053] The converter consists of four separate layers. The first layer is in the lowest part and then from top to bottom, there are layers two, three, and four. 110-04 catalyst is used in the first layer and only 111-04 catalyst is used in the second, third, and fourth layers. Vanadium pentoxide 04-110 and 04-111 is activated at 430 degrees Celsius. Vanadium pentoxide catalyst withstands heat up to 620 degrees Celsius. After the gases enter the first layer, some of the SO2 is converted into SO3. This action is accompanied by an increase in temperature, and the temperature reaches about six hundred degrees Celsius. These gases leave the first layer and are directed to the first converter. In the first converter, which is in the form of a loose tube, the gases enter the tube and are blown into it from behind the tubes to preheat the air entering the furnace, so that its temperature decreases and reaches 430 degrees Celsius, and it enters the second layer of the converter again. to be Under the first layer of the converter, the dried air can be guided through 4 pipes inside the converter so that its temperature is reduced from about 50 degrees and the thermal tolerance for the sub-converter is easier. Some of the SO2 gases entering the second layer are converted into SO3, so the temperature in this layer increases to 507 degrees Celsius. The gases leave the second layer and after passing through the pipes of the second converter, its temperature will be reduced to 430 degrees Celsius and then they will enter the third layer. In the third layer, some of the remaining SO2 is converted into SO3 and the temperature reaches 440 degrees Celsius. This heat is very important in the double absorption system where it is difficult to increase the temperature of the return gases from the first absorption tower it is cooled to 165 degrees Celsius in converter 3 and enters the middle absorption tower where all the SO3 in the gas is absorbed and SO3-free gas enters the converter No. 3 and is reheated by the heat obtained from cooling the incoming gas to the intermediate absorption tower. Also, to bring the temperature up to 430 degrees, if needed, the heat dissipated in converter 2 or 1 can also be used. After passing through the fourth layer, the remaining SO2 in this gas is converted to SO3 and finally, the conversion percentage reaches 99.8%. The exhaust gases from the fourth layer of the converter are first cooled by converter 4 and then enter the final absorption tower, where the SO3 produced in the fourth bed is also absorbed.

[0054] SO3 absorption and production of sulfuric acid:

[0055] This part consists of the following equipment:

[0056] - Middle absorption tower, which is like a dry tower.

[0057] - The final absorption tower, which is like a dry tower.

[0058] - Acid circulation tank

[0059] - Three electropumps of absorption towers, one of which is stand-by.

[0060] - Set of heat exchangers for cooling circulating and produced sulfuric acid

[0061] - Cooling tower

[0062] - Acid circulation electro pump in the heat exchanger, as well as intermediate electro pumps of the cooling tower and acid heat exchangers

[0063] - Acid concentration measurement system and adding water to the circulating acid tank to keep the production acid concentration constant

[0064] - Acid level control system in the circulation tank

[0065] - Acid storage tank

[0066] Two electric loading pumps

[0067] Middle absorption tower:

[0068] While sulfuric acid flows between the circulation tank and the intermediate and final absorption tower by the corresponding electro pump, SO3 gas enters the intermediate or final absorption tower. At this time, the SO3 entered into the intermediate absorption tower reacts with the water in the 98.5% acid and increases the concentration a little, and the concentration reaches 98.7 to 98. Then this acid enters the acid circulation tank and is balanced. With the SO3 gas introduced by the command received from the concentration meter and sending this command to the control valve, the required water enters the circulation tank, and the acid concentration is adjusted to the number set on the concentration meter which is 98.5. The absorption of SO3 in water is accompanied by heat. As a result, the heat of the circulating acid increases. The excess heat produced by the cooling tower complex - water circulation electropumps in acid converters and water circulation electropumps in the cooling tower is removed from the system. Along with water entering the circulation tank and SO3 entering the absorption tower, 18,750 kg of sulfuric acid is produced every hour, and this amount of acid produced will be removed from the system by the acid height maintenance system in the circulation tank. [Formula. 4] and [Formula. 5]

[0069] The acid removed from the circulation tank can be directed into one of the storage tanks. Acid tanks are equipped with two electro pumps. These electropumps allow us to load the acid in the tanker, move it, or direct it to the circulation tank.

[0070] Then, the remaining polluting gases from which SO2 gas has been removed, the remaining NOX and CO2 gases, which are mixed with sulfuric acid vapors, enter the nitric acid production process, and these amounts of sulfuric acid vapors will be the catalyst for the next process (nitric acid production):

[0071] Nitric acid production Pure nitric acid (HNO3)

[0072] Nitric acid melted at -41.6 degrees Celsius produces a colorless liquid, but its color ranges from yellow to brownish-red depending on the temperature and the degree of light irradiation. These changes are the result of its decomposition according to [Formula. 6].

[0073] For this reason, the containers containing it are always under controlled pressure. Nitric acid is combustible with water and its solution forms an azeotrope whose boiling point is equal to 121.9 degrees Celsius, which contains 68.7% by weight of HNO3.

[0074] Preparation methods of nitric acid:

[0075] Today, in the industrial production of nitric acid, ammonia is used as a raw material. Historically, nitric acid was first obtained from the action of sulfuric acid on sodium nitrate (Chile scale). The reaction takes place in ovens with a temperature of 150 to 170 degrees Celsius. The obtained acid has a concentration of 95 to 97%.

[0076] Brickland method:

[0077] In this method, nitric acid can be obtained from nitric oxide according to [Formula. 7].

[0078] The conversion of NO to HNO3 is done by oxidation and hydration. In this process, due to the low concentration of NO, in addition to the cost of electrical energy, some gas must also flow. At the same time, high temperature also causes the photo reaction and decomposition of NO.

[0079] Synthesis of nitric acid from ammonia:

[0080] Today, nitric acid is produced industrially from ammonia. For this, it is necessary to convert the raw material into nitrogen oxide with air. [Formula. 8]

[0081] The catalyst used in the oxidation of NH3 to NO:

[0082] The only industrial catalyst for the oxidation of NH3 to NO is the platinum-rhodium alloy, which is approximately 10% rhodium. Rhodium modifies the catalytic properties of platinum and increases its mechanical and anti-wear properties. This catalyst is usually in the form of a net with narrow threads (diameter 0.05 mm). When the catalyst is most active, ammonia is passed over it and 98% NO is obtained.

[0083] Catalyst poisons:

[0084] Chloride and sulfates such as H2S, CoS, H2S, and As2O2 are permanent poisons of the catalyst used in the combustion of NH3 to NO. Hydrocarbons such as acetylene and ethylene are temporary poisons. By removing air from the environment, their effect disappears. Fats, dust abrasives, and lubricants reduce the active surface of the catalyst, leading to clogging of the mesh holes and its failure.

[0085] NH3 to NO oxidation technology:

[0086] Although there have been improvements such as catalyst regeneration, etc, the combustion furnaces used to convert NH3 to NO are the classic combustion furnaces, which include:

[0087] Frank-Bomag furnaces:

[0088] This furnace is fed from the bottom with air and gaseous ammonia, which have already been heated with exchangers.

[0089] Parson's Combustion Furnace

[0090] The mixture of raw materials is heated with an exchanger before entering the furnace, then it enters from the top of the furnace, and after passing through the basket-like catalyst, it goes to the bottom of the furnace.

[0091] Dupton furnaces:

[0092] These furnaces are in the form of Frank furnaces, but they are fed by the Parson method. This furnace works at 6atm pressure.

[0093] We don't need the above methods because we get NO from extracting the exhaust gases of the power plant, not from ammonia oxidation with the above methods.

[0094] 1- Conversion of NO to NO2

[0095] 2- Conversion of NO2 in the vicinity of water into a mixture of HNO2 and HNO3

[0096] 3- Conversion of nitroacid due to disproportionate distribution into nitric acid and NO, which is the final stage of the process.

[0097] Methods of producing nitric acid from NO:

[0098] The methods used are different, depending on the final product. 60-50% of nitric acid can be produced with a possible concentration of 98-96% by using sulfuric acid or magnesium nitrate. that the sulfuric acid required for this part is supplied in the process of producing sulfuric acid of this project in the previous part.

[0099] Storage and transportation of nitric acid:

[0100] Nitric acid 50-60% should be transported in stainless steel containers earthenware containers or protected dark bottles, and higher concentrations should be stored and transported in inert aluminum containers.

[0101] Nitric acid production:

[0102] Nitric acid is a type of toxic acid that is highly corrosive. Pure nitric acid is colorless, but a solution of nitric acid appears yellow due to oxidation. Nitric acid is an inorganic compound whose primary use is in the production of synthetic commercial fertilizers. Its other uses include the production of explosives, metal plating, and decomposition, and it is also used in natural oxidation to produce adipic acid. Nitric acid is explosive in reaction with compounds such as cyanide, carbide, and metal powders. Meanwhile, nitric acid reacts with most metals and is used in the extraction and purification of gold. It is very common to use an aqueous mixture of 5 to 30% nitric acid and 15 to 40% phosphoric acid to clean food and dairy equipment from magnesium and calcium deposits.

[0103] Fertilizer production and nylon production:

[0104] Almost 80% of the produced nitric acid is used as an intermediate in the production of ammonium nitrate (NH4NO3) and instead, ammonium nitrate is used to produce artificial fertilizers.

[0105] 5 to 10% is also used in the production of adipic acid, this type of adipic acid is a white crystalline solid that is mainly used as the main component of nylon (6.6), which makes up almost half of it. Adipic acid is also used in the production of some low-temperature synthetic lubricants, synthetic fibers, insulators, plastics, polyurethane resins, plasticizers substances that increase plastic properties, and also as a flavoring agent. Some food products are also used.

[0106] Nitric acid production process:

[0107] Commercial nitric acid, which is produced for the fertilizer industry, is one of the dilute acids with a concentration range between 50 and 65%. Nitric acid is produced through the catalytic oxidation of ammonia (based on the Ostwald process, invented by the German chemist William Ostwald). This process has three stages:

[0108] 1- Oxidation of anhydrous ammonia by air to nitric oxide (this step is not needed in this plan because the required nitric oxide gas is supplied from the exhaust gases of the thermal power plant)

[0109] 2- Oxidation of nitric oxide to form nitrogen dioxide

[0110] 3- Absorption in water to create a solution of nitric acid and nitric oxide

[0111] This card can be done in two stages: high pressure and low pressure:

[0112] The efficiency and productivity of the first stage through low pressure are desirable, so there is no need for the first stage in this process.

[0113] While the second and third stages like high pressure. According to these considerations, the existence of two types of devices with titles of single pressure and double pressure becomes necessary.

[0114] In the plan, due to the lack of the need for ammonia in step number one, it is only needed for processes two and three of the high-pressure plan.

[0115] The efficiency of nitric oxide depends on the pressure and temperature.

[0116] At a low pressure of less than 1.7 bar and a temperature of 850-810 degrees Celsius, the efficiency of NO reaches 97.

[0117] In medium pressure from 1.7 to 6.5 bar and temperature of 900-850 centigrade, NO efficiency reaches 96.

[0118] At a high pressure of more than 6.5 bar and a temperature of 940-900 degrees Celsius, the efficiency of NO reaches 95.

[0119] Step 2- Oxidation of nitric oxide:

[0120] After the energy recovery stage in the thermal power plant and steamship and locomotive, large amounts of water vapor are released into the air, despite the waste of water in the form of steam with a temperature of five hundred degrees Celsius, which in turn will have effects on the warming of the earth. The steam produced by them, which is released into the air from the chimneys of the power plant, etc., enters this part of the device through a pipe and prevents it from being released into the air.

[0121] The steam has cooled down a bit and at this moment it has a temperature between 100 and 200 degrees Celsius (212 and 392 degrees Fahrenheit), it is passed through a cooling condenser and it reaches a temperature of 38 degrees Celsius (100 degrees Fahrenheit) with a final pressure of 7 It reaches 89 times. The water in the process steam is compressed and transferred to the absorption cylinder. Nitric oxide reacts non-catalytically with the remaining oxygen to form nitrogen dioxide and nitrogen tetraoxide.

[0122] This slow reaction is strongly dependent on temperature and pressure, that is, with low temperature and pressure, it produces the most amount in the least time.

[0123] Step 3- Absorption in water to produce nitric acid and nitric oxide solution

[0124] After cooling, the nitrogen dioxide settles at the end of an absorption tower (cylinder). A little above it, liquid dinitrogen tetraoxide is collected and deionized water is placed in the upper part of the cylinder. The absorption tower has several absorption trays (with bubble caps or sieves) where nitrogen dioxide gas is absorbed and oxidation occurs in the space between the trays. The process of absorption of nitrogen dioxide gas and its reaction with nitric acid and nitric oxide occurs simultaneously in two phases, liquid and gas.

[0125] Since this reaction is exothermic, it needs to be constantly cooled by an absorber. The nitric acid produced by the absorber has dissolved oxides within it, and the secondary air (steam) generated in the cylinder re-oxidizes NO and removes the dissolved oxides. An aqueous solution consisting of 55 to 65% nitric acid is extracted from the end of the tower. Acid concentration depends on things like temperature, pressure, number of absorption steps, and concentration of nitrogen oxides added to the adsorbent.

[0126] The bleached gases are compressed, passed through an absorbent, and sent to a steam separator where the acid vapor (acid liquid) is separated. The following waste gases are heated in the variable ammonia oxidation temperature and expanded in an electric recovery turbine.

[0127] High concentration nitric acid production:

[0128] High-concentration nitric acid (98-99% concentration) can be obtained by concentrating weak nitric acid (30-70% concentration) with an extractable still.

[0129] The distillation process must take place in the presence of a dehydrating agent (an agent that absorbs water) such as concentrated sulfuric acid (usually 60%) (produced in the previous step). In the process of concentrating nitric acid, concentrated sulfuric acid and nitric acid must be He put 55 to 65% in a sealed and dehumidified cylinder at a pressure almost equal to atmospheric pressure. The acid mixture moves downwards in the opposite direction of the generated vapors, and the concentrated nitric acid moves downwards, leaving 99% steam, a small amount of NO2 and oxygen (O2) at the top of the cylinder, which is caused by the decomposition of They are nitric acid. The concentrated steam leaves the cylinder goes to the bleaching section and meets the condenser system to effect the condensation of strong nitric acid and the separation of oxygen and oxides of nitrogen by-products (NOx). The byproducts then move to the absorption cylinder, where the nitric oxide mixes with the auxiliary air to form NO2, which is recycled as weak nitric acid. Stagnant and inaccessible gases are released into space from the top of the absorption cylinder.

[0130] Types of publications:

[0131] Emissions from nitric acid production plants include NO, NO2, a very small amount of HNO3 vapor, and ammonia (NH3). Table 2 shows the common limitations in sustainable operations. The NOx level will increase at the start of the process, and this increase will continue until the process reaches a steady state. In a properly operated acid plant, there should not be any steam emissions as these steams should be captured and removed by the steam separator.

[0132] For medium-pressure absorbers between 1000 and 2000 ppm.

[0133] For high-pressure absorbers between 100 and 200 ppm.

[0134] Considering that NOx emissions depend on the kinetics (kinetic rate) of nitric acid formation and the type of tower design, the subsequent gases from the absorption tower are the main source of nitrogen oxides. NOx emissions can increase in some conditions, such as: if the air supply to the oxidizer and absorber is not optimized, if the absorber pressure is low, if the cooling condenser and absorber are at too high a temperature, if too concentrated acid is produced. , and when the operation is performed with high-scale inputs. At the same time, one should be extremely careful about compressors and pumps because any errors in these areas can lead to pressure drop and leakage and reduce the productivity of the factory.

[0135] NOx emissions can be controlled through extended absorption non-selective catalytic reduction (NSCR) and selective catalytic reduction (SCR) systems. Nitrogen oxide (N2O) emissions depend on the amount and type of NOx emission control activities.

[0136] Non-selective catalytic reduction (NSCR) systems are very effective in controlling N2O emissions, while selective catalytic reduction (SCR) systems not only do not reduce N2O emissions, but increase them.

[0137] Currently, in the production of nitric acid, long absorptions can be used to reduce NOx emissions. In this method, the efficiency of the absorption tower can be improved both by increasing the size and number of absorption trays and by adding a secondary absorption tower. Productivity can be achieved through absorption at high pressure.

[0138] The emission of NOx reaches less than 100 pp, or the cooling of the weak acid liquid in the absorber increases.

[0139] NSCR systems use fuel and a catalyst to consume free oxygen in subsequent combustions and convert NOx to elemental nitrogen. The advantage of these systems is that they can reduce N2O emissions from 80 to 90%. The gas produced from NOx reduction can be passed through a gas expander for energy recovery and then released out of the stack. NSCR systems are not very popular and used for two reasons: firstly, their fuel costs are very high, and secondly, they require high-temperature gas expanders, which must be made of toxic materials. In addition, the cost of their maintenance and repair is very high, and the reconstruction of the heat recovery system in the old ways, which is necessary for installing these systems, is not economical at all.

[0140] The SCR system can be added to this current system to significantly reduce NOx emissions. In SCR systems, ammonia is mixed with preheated NOx gases and reacts with them in the presence of a catalyst such as vanadium pentoxide or plentonium to produce nitrogen and water. Since ammonia is ready and available in nitric acid production factories, this control system is known to be a popular and attractive system. The exhaust gas from the expander must be kept at a high temperature to avoid the precipitation of ammonia salt. The disadvantage of these systems is that a small amount of ammonia may escape (known as ammonia slippage) and the N2O emissions are not reduced.

[0141] Using the Procal P2000 analyzer:

[0142] The Procal P2000 is an infrared analyzer capable of in-situ analysis of up to 6 emission compounds in gas phases. As soon as the process gas enters the in-situ sample cell, this analyzer uses the reflective beam principle to measure and evaluate the process gas. Mid-IR pulses, at two specific wavelengths for each observed compound, are transmitted through the sample cell. The "measurement" pulse is approximately (partially) absorbed by the gases under measurement, but the "reference" pulse remains unaffected. Up to eight wavelengths are available, sometimes sharing wavelengths, thus enabling the simultaneous monitoring of six compounds in the gas phase. The operation, zeroing, and calibration in all operating modes are completely unchallenged and use the same visual and system combinations.

[0143] The Procal 2000 analyzer can measure nitric oxide (NO) up to 300 ppm and can also measure nitrogen dioxide (NO2). This analyzer can be placed both in the inlet and outlet of the catalytic reactor and can be used to monitor the efficiency of the catalytic reactor and control its operation.

[0144] From the exhaust gases of the thermal power plant and locomotive diesel engine and steamship, SO2 and NOX suspended particles were absorbed as much as possible with the above methods, and the rest of the gases will be carbon dioxide and mono oxide.

[0145] CO gas does not have a special absorption method, it is necessary to prevent incomplete combustion by using good oxygenation in the combustion stage by turbos, but to absorb the remaining CO2 gas in the exhaust gases and produce bicarbonate from it by the following method:

[0146] Production of sodium bicarbonate from CO2 gas and introducing the method of producing sodium carbonate from carbon dioxide gas extracted from thermal power plant chimneys and fossil fuel engines:

[0147] Sodium carbonate production processes available in the industry:

[0148] 1- Chemical synthesis of sodium carbonate through the Solvay process.

[0149] 2- Production of sodium carbonate from mineral sources

[0150] In the chemical synthesis method, limestone and ordinary salt are used as raw materials. First, salt is dissolved in water to obtain a salt solution. Then this solution is saturated with ammonia gas.

[0151] Carbon dioxide gas produced from the heat of limestone is blown into the prepared solution.

[0152] In this method, we will not need this step because we supply the carbon dioxide gas from the exhaust gases of the power station.

[0153] Therefore, CO2 gas is injected into the solution of salt water and ammonia

[0154] and leads to the production of sodium bicarbonate. Then sodium bicarbonate is heated until it decomposes and sodium carbonate is produced.

[0155] The Solway process is carried out using NaCl salt and CaCO3 limestone as raw materials and the presence of ammonia as a catalyst in different stages results in the production of sodium carbonate.

[0156] But we do not need limestone in this method, only brine and ammonia are the raw materials needed, and it is more affordable than the Solway method.

[0157] Different stages include sodium bicarbonate production, sodium carbonate production, and ammonia recovery.

[0158] The first stage of sodium bicarbonate production:

[0159] The reaction is carried out by passing the concentrated salt water (brine) solution through the tower sequentially. In the tower, ammonia bubbles rise from the bottom of the tower and are absorbed and dissolved by the salt water solution. In the second stage, by injecting carbon dioxide gas, the bubbles of this gas pass through the ammonia salt water solution, and sodium bicarbonate is obtained. The carbon dioxide required for this stage is obtained from the exhaust gases of the thermal power station.

[0160] The solution resulting from this process includes sodium bicarbonate and ammonium chloride solution which after passing through the filter, sodium bicarbonate is separated and can be transferred to the second stage for the production of sodium carbonate.

[0161] The third stage of recycling:

[0162] In the side part of this process, there is ammonium chloride, which can be sold as a side product.

[0163] In the production process of sodium bicarbonate, ammonia is added to the reaction in a small amount only for the amount of waste, and the main raw materials are sodium chloride salt and energy. In addition to sodium bicarbonate, the obtained products are also ammonium chloride.

[0164] In addition to useful industrial uses, sodium bicarbonate can be used to produce sodium carbonate by heating up to 200 degrees Celsius, which is outside of our plan.Advantage Effects of the Invention

[0165] -Using special acid filters to filter pollutants

[0166] - Reduce costs

[0167] - Converting CO2, NOX, and SO2 emissions into profitable products of sulfuric acid, nitric acid, and sodium bicarbonate and generating income from them is equivalent to selling electricity from burning fuel.

[0168] - Removing polluting gases is healthy for nearby power stations too.

[0169] Shows a flowchart of CO2 gas becoming sulfuric acid.

[0170] presents a flowchart of NOX becoming nitric acid.

[0171] is a flowchart that shows how bicarbonate sodium and sodium chloride were produced.

[0172] Shows that in the stratified tower with the V2O5 catalyst, SO2 gas becomes SO3 gas, and then in the absorbent cooling tower, this gas is converted into dilute liquid sulfuric acid.

[0173] shows that after absorbing SO2 gas and producing sulfuric acid, the remaining gases including NOX enter a tower with a pressure of 7.3 BAR and a temperature of 100 F, and NO3 is extracted and this is placed in the vicinity of the water vapor exit of the thermal power plant and steam locomotive which is released into the air without use, and turns into dilute nitric acid.

[0174] shows the rest of the output gases are the remaining CO2 gas, which enters the ammonia tower and salt water and becomes sodium bicarbonate and ammonium chloride, which without sodium carbonate has many industrial uses.Examples

[0175] By installing thermal and fossil fuel power plants and connecting the exhaust fumes of the polluting gases of this power plant and using the wasted water vapor from the fumes of these units and SO2 NOX CO2 gases, these exhausts are converted into industrial materials. Sulfuric acid, nitric acid, and sodium bicarbonate are best sellers.

[0176] The mentioned formulas in the solution section:

[0177] [Formula. 1] Conversion of SO2 to SO3 in the thermal catalytic tower:

[0178]

[0179] [Formula. 2] SO3 gas and acid move in the opposite direction of each other, in such a way that the acid moves down from the top of the tower as a spray, and the gas flows from the bottom to the top of the tower. During this movement, the SO3 gas is absorbed by the acid, creating oleum or fuming sulfuric acid, which is the same acid with a high percentage of SO3.

[0180]

[0181] [Formula. 3] following the previous one:

[0182]

[0183] [Formula. 4] related to the absorption tower part:

[0184]

[0185] [Formula. 5] related to the absorption tower section:

[0186]

[0187] [Formula. 6] Production of pure nitric acid:

[0188]

[0189] [Formula. 7] Getting nitric acid from nitric oxide:

[0190]

[0191] [Formula. 8] Obtaining nitric acid from ammonia by converting the raw material with air to nitrogen oxide:

[0192]

[0193] This invention will be very widely used in permanent fossil fuel units such as thermal power stations and diesel engines of fossil fuel ships and diesel locomotives

Claims

A device to remove pollutant gases from the exhaust of thermal power plants, locomotives, trains, and ships with fossil fuel diesel engines that include SO2, NOX, CO2, and suspended particles and reabsorb them in the direction The production of sulfuric acid, nitric acid and sodium bicarbonate is used, which consists of the following components:1- Connecting pipe to the chimney outlet2 - Water tank to remove suspended particles3- Sulfuric acid production system4- Nitric acid production system5- The main and large tanks for the production and storage of sodium bicarbonateAccording to Claim 1, this device is designed to create a closed system that prevents the release of polluting gases in the air, through a connection pipe connected to the exhaust fume hood, all its gases enter the inlet of this device to perform the rest of the process.According to claim 2, suspended particles in the water tank entering the system must be separated from the outgoing gases.According to claim 3, SO2 gas must be removed from the exhaust gases in the production of sulfuric acid so that it does not interfere with the reaction in the final process of bicarbonate production.According to claim 4, the sulfuric acid produced is a catalyst along with the excess steam from the boiler for the next stage of producing nitric acid from NOX gas.According to claim 5, the remaining gases from the previous stage after removing SO2 enter the stage of the scientific and practical production process of nitric acid from NOX gas to be removed from the exhaust gases.According to claim 6, the water contained in the excess water vapor of the thermal power plant and the steam locomotive and ship is compressed for this process and transferred to the absorption cylinder as a reaction aid.According to claim 7, dilute nitric acid enters the concentration tower with sulfuric acid produced in the previous steps, so that the material produced from the previous process is concentrated in this consumption step of the nitric acid production process and stored in tanks.According to claim 8, the rest of the polluting gases, which is CO2, enter the zero-degree water and salt tower and are mixed with ammonia gas turns into sodium bicarbonate and ammonium chloride and is stored in separate tanks.According to claim 9, considering that the production volume of CO2 gas in polluting gases is more than other gases, to reach this stage, other intervening polluting gases should have been removed from the contents of the gases according to the previous process so that in the reaction The production of sodium bicarbonate as a more harmless substance and in larger amounts than other products does not interfere.

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