WO2006128326A1

WO2006128326A1 - Comprehensive coal burning boiler smoke and ash slag treating process with no pollution emission

Info

Publication number: WO2006128326A1
Application number: PCT/CN2005/000809
Authority: WO
Inventors: Hanxiang Shi
Original assignee: Hanxiang Shi
Priority date: 2005-05-30
Filing date: 2005-06-08
Publication date: 2006-12-07
Also published as: CN1687637A

Abstract

The invention relates to a comprehensive coal fired boiler smoke and ash slag treating and reuse process. It includes air separation to produce oxygen, water electrolysis to produce oxygen and hydrogen, coal burning boiler, boiler fume dust, molecular sieve preparation, boiler fume purification, carbon dioxide purification, CO2 slow releasing gas fertilizer preparation, CO2 utilization and so on. Molecular sieve is prepared mainly from coal fired slag and CO2 gas fertilizer is prepared from molecular sieve absorbing CO2 coming from coal fired fume purification. Then the prepared gas fertilizer can be top-dressed to the soil, especially to the dry soil and saline-alkaline soil. The rest CO2 can be used as the raw material for the organic synthesis or used as the extraction agent, refrigerant or fumigant in the food industry. So all the pollution coming from coal combustion is treated and reused and no pollution is produced.

Description

Coal-fired boiler comprehensive treatment without pollutant emission technology

The invention relates to coal-fired flue gas treatment and ash slag utilization technology, in particular to a coal-fired boiler comprehensive treatment non-polluting emission technology, belonging to the international patent classification F23B5/00 "equipment capable of burning unburned substances at initial combustion" technology field. Background technique

Coal-burning pollution to the environment - Coal is a flammable substance that has been transformed from the complexities of biochemistry, geochemistry, physico-chemicals, etc. during the long period of geological conditions after the accumulation of plant remains in swamps or lakes in various historical eras. The coal-oxygen combination reaction releases a large amount of light and heat, which is the combustion of coal. Coal-fired boilers are the most important form of energy produced by the combustion of coal. They vaporize water into steam and use steam to drive generators or use them as heat sources. Coal consists of carbon, volatiles, moisture and ash. The elements constituting the coal are (, H, 0, N, S, P, F, Cl, Fe, Al, Ca, Si, Mg, Mn, etc., and these elements participate in the reaction to form flue gas and ash when the coal is burned.

In addition to dust and moisture, coal-fired flue gas also contains S0 ₂ , N0 _X , C0, C0 ₂ , C _x H _y and harmful gases such as fluorides and chlorides, which cause serious pollution and damage to the atmosphere. 70% of the dust emitted into the atmosphere, 90% of S0 ₂ , 70% of N0 _X , 71% of C0, 43% of C _X 3⁄4 and 85% of C0 _{2 are} derived from coal combustion. When burning coal, a large amount of ash that affects the environment is generated, and these ash are not fully utilized. So ₂ in the flue gas is mainly generated from coal and pyrite in the number of sulfide is reacted with oxygen; N0 _X mainly by oxidation of coal from some organic compounds, a small amount of air in the oxidation from N; C0, C0 ₂ is a reaction between C and 0 in coal, and C0 ₂ is mainly formed when coal is completely burned, and CO content is increased when incomplete combustion. C0 ₂ is the root cause of the "greenhouse effect", ≤ 0 ₂ and N0 _X are the culprit in the formation of "acid rain". S0 _2, ΝΟχ and fluorides, chlorides and other atmospheric pollution is very serious, in terms of its emissions, far less C0 ₂ large recycling C0 ₂ is the inevitable road, otherwise ₍₀₂ no way out, it It is impossible to eliminate the pollution of coal-fired flue gas. If the pollution of S0 ₂ , N0 _X and fluoride, chloride and the like is simultaneously solved in the process of recovering C0 ₂ , the pollution of coal-fired flue gas will be completely eliminated.

Although there are many ways to reuse ash, it is indeed recycled in places where conditions permit, but more than 50% of the ash is not used, still occupying land and polluting the environment. Only in the treatment of flue gas pollution, to solve the reuse of ash, in order to fully solve the problem of coal burning.

Current coal-fired flue gas treatment and utilization of ash and slag -- The pollution caused by burning coal has been highly valued by all countries in the world and many technical measures have been adopted. There are many ways to get rid of S0 ₂ and N0 _X in the flue gas, and remove S0 ₂ and! At the same time, fluoride and chloride are generally removed. The chief culprit of the "greenhouse effect" C0 ₂ has a large share of the flue gas. It is difficult to completely remove the pollution of C0 ₂ from the flue gas. Recycling C0 ₂ is the inevitable path. Otherwise, no Way out.

Coal combustion is the main form of coal utilization. It is inevitable that C and 0 will react to produce co ₂ . Trying to make "co ₂ harm to profit" is the best way to solve its pollution.

Pure co ₂ is very versatile: co ₂ is a good extractant for processing and extraction of food, beverages, oils, spices, and pharmaceuticals; co ₂ is a good refrigerant, not only has a fast cooling rate, but also has good handling performance. It does not wet the product, it will not cause secondary pollution, and it has less investment and saves manpower; co ₂ is a fresh-keeping and storage agent for vegetables and fruits with good quality and low price; co ₂ is a good food storage fumigant. Not only excellent insecticidal and rodent control performance, but also moisture and mildew proof; co ₂ can be used as oil field injection agent to effectively drive oil, can be used as oil field washing agent to clean the plug of oil well; co ₂ is also effective gas fertilizer, used for The effect of planting in greenhouses is obviously obvious. C0 ₂ These uses tell us that we can't just see the harmful side of it. C0 ₂ also has a usable side that should be fully utilized. However, these uses have not been able to fundamentally solve the problem of contamination of co ₂ , and most of them are still discharged into the atmosphere in the form of gas after use. Only by changing the form of co ₂ to make it another substance, fixing co ₂ can really improve co ₂ pollution.

Plants absorb co ₂ by photosynthesis and combine it with water and a small amount of nutrients into various organic substances, converting C0 ₂ into other forms of matter, truly consuming C0 ₂ and reducing the amount of C0 ₂ entering the atmosphere. Higher plants can consume C0 ₂ and lower plants can also consume C0 ₂ . For example, plankton as a unicellular plant, like all plants, can use solar energy to combine carbon dioxide, water and trace nutrients to form organic matter. The carbon atoms in the co ₂ molecule are rooted in the captive organism and become safe. Resources, called carbon deposition. A single-celled algae plant that absorbs a large amount of carbon dioxide to form oil. This algae plant can be directly used in an engine for combustion and power generation without refining.

It is converted into organic products through modern organic synthesis technology. Co ₂ can be used for catalytic hydrogenation, synthesis of methane, methanol, ethanol and other alcohols, synthesis of formic acid and its derivatives, direct synthesis of hydrocarbons or conversion to co, and synthesis of hydrocarbons by Fischer-Tropsch synthesis. The product, its catalytic hydrogenation product is shown in Figure 1.

Among the products of co ₂ catalytic hydrogenation, methanol and methane and other hydrocarbons can be used as fuels to replace the currently used petroleum as part of the energy source. Methanol, methane and other hydrocarbons (especially C2~C5 lower hydrocarbons and gasoline fractions containing C6 or higher) are important and raw materials for organic chemicals. Synthesis of esters and polymers from C0 ₂ as raw materials: Synthesis of propylene carbonate from C0 ₂ and propylene oxide, which is replacing the transesterification method, phosgene method and chloropropanol method due to its low production cost and high product quality; co ₂ with propylene oxide synthesis, co ₂ direct synthesis of alcohol production carbonate, aliphatic polycarbonate resins by adjusting the polymerization liquid, produced with this material biodegradable polyurethane Foam plastics.

Organic synthesis based on co ₂ can also convert CO ₂ to another substance, and C0 _{2 is} fixed to reduce the emission of co ₂ to the atmosphere.

The above analysis is sufficient to show that co ₂ is an available resource, and it is possible to maintain the balance of C0 ₂ in nature.

2. Separation and purification of ∞ ₂

_{Concentration} of coal combustion flue gases produced by co air, excess air ratio due to different changes, generally between 13~19%, after separation, purification can be effectively utilized. There are many methods for separating, concentrating and purifying C0 ₂ , and the mature methods include physical method, chemical method and membrane separation technology.

The cryogenic distillation method and the pressure swing adsorption method in the physical method are most suitable for the separation and purification of C0 ₂ in coal-fired flue gas. Low-temperature distillation method has high cost and high separation efficiency, so it is not suitable for small and medium-scale production. The pressure swing adsorption process is simple, low energy consumption, strong adaptability, high degree of automation, and technology. Advanced, economical, and widely used.

The chemical method mainly uses organic amines (such as ethanolamine, diethanolamine, triethanolamine, etc.) as a solvent to absorb C0 ₂ , and absorbs and desorbs to obtain high purity C0 ₂ .

Membrane separation technology has the advantages of simple device, convenient operation and low energy consumption. It is an energy-saving gas separation technology that is developing rapidly in the world today. However, the disadvantage of the membrane separation method is that it is difficult to obtain high-purity co ₂ , and in order to obtain high-purity co ₂ , it is necessary to have a chemical method.

3⁄4 R

Before C0 _{2 is} separated, concentrated, and purified, the flue gas must be purified to remove dust, C0, S0 ₂ , N0 _X , fluoride, chloride and other impurities in the flue gas. The method of removing these impurities is more mature and can be used for reference.

3. Utilization of ash and slag

One of the components of coal, ash, becomes mostly solid during the combustion process, and ash is formed with unburned carbon, which is discharged as waste. A part of it enters the flue gas in the form of dust. Collected in the product. At present, coal ash is basically used to produce building materials, road construction, backfilling, etc. It can also make full use of its characteristics and open up more value-added utilization channels.

In order to eliminate the pollution and damage caused by coal combustion, many people have taken Technical measures, but these technical and technical measures exist in isolation from each other, do not form comprehensive control technology, can only solve individual local problems, and cannot completely eliminate coal-fired pollution in a coordinated manner. How to adopt comprehensive technology to completely eliminate coal-fired pollution is the problem we have to solve. Disclosure of invention

The object of the present invention is to provide an integrated treatment plan for the comprehensive treatment of coal-fired pollutants in view of the current shortage of coal-fired pollutants treatment technology. This is based on a variety of aspects of coal-fired pollution, both gaseous and solid. When polluting pollution, individual pollutants cannot be considered in isolation. According to the characteristics of each pollutant, and the mutual control, comprehensive, systematic and comprehensive development of the treatment plan, in order to get the most benefit with the least investment.

The technical solution of the present invention is as follows.

A coal-fired boiler comprehensive treatment non-polluting technology, the technology includes: "air separation system 0 ₂ ", "electrolyzed water system 3⁄4, 0 ₂ ", "fired boiler", "flue gas dedusting", "molecular sieve manufacturing ", "Fume purification", "C0 ₂ purification", "slow release C0 ₂ gas fertilizer preparation", "C0 ₂ utilization" a number of processes combined. The ash produced by burning coal is made into coal ash slag molecular sieve, adsorbing co ₂ , and becomes a slow-release C0 ₂ gas fertilizer with water retention effect. All of them return to nature in the shape of fertilizer, and realize pollutant-free discharge of coal-fired boiler. .

The "coal-fired boiler" includes an oxygen-enriched coal-fired boiler in addition to the usual air-fired boiler; the difference between the oxygen-enriched coal-fired boiler and the usual air-fired boiler is that: the gas sent to the boiler is not air It is an oxygen-rich gas, and the oxygen content of the oxygen-enriched gas is > 21%; it is generally considered to be 80%-90%; the oxygen-rich gas required for oxy-combustion of coal is obtained by separating or electrolyzing water.

It is also possible to use an oxygen-rich combustion coal in an air-fired boiler, as long as the flue gas is returned to a part and mixed with an oxygen-rich gas into the furnace, so that the oxygen content of the furnace mixture can be maintained at 21%, the air-fired boiler No changes are required.

The coal ash slag molecular sieve is a molecular sieve prepared by burning ash generated by coal as a main raw material, and the molecular sieve is equivalent to the 4A type, and the preparation method is as follows:

(1) grinding the cinder to 150 mesh, mixing with fly ash to form a coal-fired ash mixture powder,

Al (0H) ₃ and Na ₂ C0 ₃ or NaOH are baked at 120 ° C for 2-3 hours to remove moisture, then mixed evenly, ― (2) calcined at 800-850 ° C temperature 1- 1. 5 hours, after being light green material, crushing; (3) Under stirring, the pulverized material is put into water, heated to 50-55 ° C, and kept at a constant temperature for 2 hours, and the liquid is analyzed for alkalinity, and the total alkalinity is added to 1 N;

(4) heating to 98 ° C, crystallization for 6 hours under stirring;

(5) Washing, exchange, molding, and activation according to the conventional molecular sieve method to obtain the product, and the moisture-proof sealed package is ready for use;

(6) Instead of N C0 _:! (or NaOH), K ₂ C0 _: , (or K0H) may be used as needed.

The preparation of the sustained-release CO ₂ gas fertilizer is in a dry state, the pure CO ₂ gas passes through the coal ash slag molecular sieve bed, and the coal ash slag molecular sieve fully adsorbs the C0 ₂ gas, and becomes a "slow release ∞ ₂ gas. Fertilizer", sustained release (0 ₂ gas fertilizer in the closed conditions, moisture storage.

In order to reduce the accumulation of Na ions, in the preparation of coal ash slag molecular sieves, the K salt (or K base) is used instead of the Na salt (or Na base).

The coal-fired boiler comprehensive treatment non-polluting technology of the invention adopts "slow release C0 ₂ gas fertilizer" as the core, and is composed of "air separation system 0 ₂ ", "electrolyzed water system, 0 ₂ ", "burning coal boiler", "Fume removal dust", "molecular sieve manufacturing", "flue gas purification", "∞ ₂ purification", "slow release C0 ₂ gas fertilizer preparation", "C0 ₂ utilization" and other processes are combined. The coal ash slag molecular sieve is produced by using ash generated by coal combustion as the main raw material, and the molecular sieve is used to adsorb co ₂ in the coal-fired flue gas into a slow-release co ₂ gas fertilizer, and the gas fertilizer is gradually applied to the soil to adsorb moisture. The newly adsorbed water occupies the position of the originally adsorbed co ₂ , and co _{2 is} gradually replaced and released, supplementing the co ₂ for the photosynthesis of the plant. The water adsorbed by the slow-release co ₂ gas fertilizer is not easy to be lost and evaporated, so it plays a role in retaining water for the soil, and is very suitable for drought-scarce, sandy saline soil. Because of the large amount of co ₂ produced by coal combustion, in addition to the preparation of "slow release co ₂ gas fertilizer", it can also be used for organic synthesis, or it can be directly used in the food industry, as an extractant, a refrigerant, Fumigant, oil field washing agent, etc. To create conditions for co ₂ adsorption, the flue gas is treated first, dust and harmful gases are removed and utilized to increase the co ₂ concentration. In this way, all the pollutants produced by coal combustion must be treated and utilized to achieve pollutant-free emissions.

The use of oxy-combusted coal greatly reduces the amount of flue gas generated, greatly reduces energy consumption, and improves fuel utilization, which also creates favorable conditions for C0 ₂ adsorption. Using air separation and electrolyzed water technology to provide oxygen source for oxy-combusted coal, electrolyzed water technology can provide oxygen for C0 ₂ organic synthesis while providing oxygen.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view of the direction of catalytic hydrogenation of carbon dioxide;

2 is a schematic view showing the process of the first scheme of the pollutant-free discharge of the coal-fired boiler; Figure 3 is a schematic diagram of the process of the second scheme of the non-polluting emission of the coal-fired boiler; Figure 4 is a schematic diagram of the technical scheme of the third scheme of the non-polluting emission of the coal-fired boiler; . The best way to implement the invention

1, program one

As shown in Figure 2, the process of the first scheme includes "flue gas dust removal", "molecular sieve manufacturing", "flue gas purification", "C0 ₂ purification", "slow release C0 ₂ gas fertilizer preparation", "C0 ₂ utilization". Wait.

The coal is burned with air in the boiler to produce flue gas and ash. The flue gas contains a large amount of C0 ₂ oxidized by air, N ₂ , 0 ₂ , and C, as well as dust and harmful gases such as S0 ₂ , N0 _X , C0, C _x H _y , HC1, and HF. The flue gas is first removed by the "dust removal" process, and the S0 ₂ , N0 _X , HC1, HF and other compounds are removed by the "flue gas purification" process to obtain flue gas containing only N ₂ , 0 ₂ , C0 ₂ ; The "C0 ₂ purification" process separates C0 ₂ from the mixed gas, and a part of pure C0 ₂ is adsorbed by the coal ash slag molecular sieve obtained by the "molecular sieve manufacturing" process as a "slow release gas fertilizer", and a part of pure C0 _{2 is} used for "Organic synthesis", part of C0 _{2 is} directly used in the food industry, used as extractant, refrigerant, fumigant, oil field washing agent, etc.; finally, N ₂ and 0 _{2 are} empty without any harm. The ash is used to prepare a coal ash slag molecular sieve.

1), "Fume removal"

No matter what kind of coal-fired boiler, the smoke will bring a lot of dust, especially the dust in the pulverized coal furnace and the circulating fluidized bed furnace. The dust in the flue gas is not allowed to be discharged into the atmosphere, nor can it be brought into the system to affect the reuse of other components. Measures must be taken to remove the dust from the flue gas. The dust in the flue gas is the solid matter formed by the ash in the coal during the combustion of the coal, and the unburned carbon is also contained in the flue gas. Generally, coal-fired boilers in power stations use electrostatic precipitators and bag filters to complete the dust removal task, which can meet the requirements of the rear process.

2), "Fume purification"

The purpose is to remove compounds such as S0 ₂ , N0 _X , HC1 and HF in the flue gas. At present, there are many related technologies and the effect is also very good. Among them, the "activated carbon ammonia method" is the most suitable, not only can effectively remove the above compounds, but also Production of ammonium sulfate and ammonium nitrate mixed fertilizer.

3), "C0 ₂ purification"

Because the amount of C0 ₂ produced by coal combustion is very large, it is difficult to digest all of them in a single application. At the same time, it should be used for a variety of purposes. Different applications have different requirements for co ₂ quality, and should be graded separately for the purpose. In this scheme, "co ₂ purification" is divided into two-stage purification, and the first stage adopts membrane separation or pressure swing adsorption multi-method, so that C0 _{2 is} increased to about 90% for direct gas fertilizer and used to produce gas mitigation; The grade is chemically or cryogenically distilled, and the concentration is 99%. Industry grade or 99. 95% food grade C0 ₂ , used to synthesize organic matter and used in the food industry.

4), "Molecular sieve manufacturing" and "sustained release C0 ₂ gas fertilizer preparation"

This is the core part of the program and is a comprehensive flue gas treatment technology that combines coal ash slag with recycling C0 ₂ .

"Molecular Sieve Manufacture"

"Molecular sieve" is an aluminosilicate which is mainly composed of silica-alumina through an oxygen bridge to form an open network crystal structure. In the network structure, there are many pores with uniform pore size and well-arranged cavities with large internal surface area. Its network porous structure makes it have a high adsorption capacity and has the property of molecular selective adsorption. Molecular sieves have very good adsorption properties for water and carbon dioxide. If the molecular sieve adsorbs C0 ₂ and is used as a gaseous fertilizer, this "gas fertilizer" can release co ₂ very slowly, and the molecular sieve after releasing co ₂ is still a very good water retaining agent. . However, the usual molecular sieve production cost is high, and it is economically unreasonable to use it as a fertilizer after adsorbing C0 ₂ . Molecular sieves are made from coal-fired ash slag rich in silicon and aluminum. It is obvious that the molecular sieve has low manufacturing cost and is economically reasonable as a fertilizer after adsorbing co ₂ . More importantly, a fundamental way out for coal ash slag is found. The "greenhouse effect" gas C0 ₂ and ash generated by coal combustion are simultaneously utilized to realize "turning waste into treasure".

Coal-burning ash is formed by the ash in the coal during the combustion process. Its chemical composition depends on the ash content of the coal. Usually, the ash content of the coal contains a large amount of chemical elements required for synthetic molecular sieves such as silicon and aluminum. The chemical composition of fly ash is listed in Table 1:

Table 1

The chemical composition of coal-fired slag is basically the same as that of fly ash. The origin and variety of coal are different, and the ash composition is different. There will always be differences. Moreover, the proportion of the chemical components of the coal ash slag is not the ratio required by the molecular sieve, and the batch adjustment is required. Molecular sieve for adsorbing carbon dioxide was Type 4A molecular formula may be expressed _{as:... NaO A1A Si0 2} 4. 5H 2 0, three components Na0, A1 ₂ 0 _3, Si0 ₂ ratio of molecules of 1: 1: 1, In this proportion, add appropriate amount of Al (0H) 3 and N3⁄4C0 ₃ . The preparation method of coal ash slag molecular sieve is as follows:

(1), grinding the cinder to 150 mesh, mixing with fly ash and dust into coal ash slag mixed powder, Al (OH) fl N3⁄4C0 ₃ three materials are baked at 120 ° C for 2-3 hours, Remove moisture and mix well.

(2), calcined at a temperature of 800-850 ° C for 1-1. 5 hours, into a light green material and then pulverized. T/CN2005/000809

(3) Under stirring, the pulverized material is put into water, heated to 50-55 ° C, and kept at a constant temperature for 2 hours. The alkalinity is taken for liquid extraction, and the total alkalinity is added to 1 N.

(4), the temperature was raised to 98 C, and crystallized under stirring for 6 hours.

(5), according to the conventional molecular sieve method for washing, exchange, molding, activation, the product, moisture-proof sealed packaging for use.

"Slow release co ₂ gas fertilizer preparation": In the dry state, pure co ₂ gas passes through the coal ash slag molecular sieve bed, coal ash slag molecular sieve fully adsorbs C0 ₂ gas, becomes "sustained release co ₂ gas fertilizer" . Sustained release (0 ₂ gas fertilizer is prevented from being stored under closed conditions).

5), "Slow release C0 ₂ gas fertilizer"

Photosynthesis is the process by which plants use light energy to synthesize carbon dioxide and water into organic matter in the chloroplast, release oxygen, convert light energy into chemical energy, and store it in organic matter. Plants rely on photosynthesis to grow, and sufficient carbon dioxide is an essential factor in ensuring the normal growth of plants. The lack of carbon dioxide plants cannot grow normally. In relatively closed greenhouses (including plastic grids), as plant photosynthesis progresses, the concentration of co ₂ in the gas gradually decreases, affecting the normal photosynthesis of plants and affecting the normal growth of plants. Timely supplementation of C0 _{2 to} maintain its normal concentration is essential to ensure the normal growth of plants. Not only that, but practice has shown that increasing the concentration of co _{2 in the} atmosphere of plant growth can increase plant yield. This is the reason for the co ₂ gas fertilizer. Co ₂ gas fertilizer is not only suitable for greenhouses, but also can increase the yield of field crops if applied properly. At present, there are two ways to apply co ₂ gas fertilizer: canned on-site application or direct application of on-site gas production. Both methods of administration is difficult to ensure equilibrium C0 ₂ concentration, C0 ₂ gas utilization rate is low. If a substance is selected as the CO ₂ carrier, the carrier adsorbs co ₂ and the co _{2 is} slowly released in an orderly manner, which not only ensures the equilibrium of the co ₂ concentration, but also improves the utilization of the co ₂ gas. This carrier does not cause damage to plants and soil, and it is also preferable to produce its effects. The molecular sieve made of coal ash slag can play the role of adsorbing C0 ₂ in a dry state, and it contacts and adsorbs water in the soil after application, and the adsorbed water gradually replaces co _{2 .} Occupying the adsorption surface, co _{2 is} gradually released, and this release is relatively stable and orderly. The product obtained by adsorbing co _{2 from} this coal ash slag is called "sustained release ∞ ₂ gas fertilizer". The water adsorbed by the molecular sieve is not easily lost and evaporated in the soil, and the molecular sieve plays a role of retaining water. Researchers in China and Japan have developed research on the use of such coal-fired ash molecular sieves (which they call synthetic zeolites) to improve sandy soils. The results confirm the incorporation of synthetic zeolites in sandy soils. It is called coal ash slag molecular sieve), which increases the water content of the soil, thereby increasing the growth and harvest of the crop. At the same time, it can reduce the amount of irrigation water, help reduce the salt damage of the soil, and apply the coal ash slag molecular sieve. It is an effective measure to improve sandy saline soil. We also It is noted that a large amount of Na ions are introduced during the preparation of the coal ash slag molecular sieve, and the Na ions in the soil are increased after the application. In order to overcome this defect, in the process of preparing the molecular sieve, K0H or K C0 _{3 is} substituted for ^^[[] or ^[(:0 ₃ , which not only avoids the increase of Na ions, but also increases the fertilizer element K for the soil.

6), "C0 ₂ utilization"

C0 ₂ utilizes the preparation of "sustained-release C0 ₂ gas fertilizer", as well as excess C0 ₂ for direct utilization and synthesis of organic products.

Direct use of C0 ₂

As mentioned above, co ₂ can be directly used as an extractant, a refrigerant, a fresh-keeping storage agent, a food storage fumigant, an oil field washing agent, and the like. Due to the different requirements for the quality of C0 ₂ for different purposes, 90% and 99% industrial grade, 99.95 °C food grade and other grades are selected according to actual needs. Typically, the C0 ₂ package is in canned form.

C0 ₂ organic synthesis

As mentioned above, C0 ₂ can be used to synthesize many organic products, including methane, methanol, ethanol and other alcohols, formic acid and its derivatives, other hydrocarbons (especially C2~C5 lower hydrocarbons and gasoline containing C6 or higher). Distillate); It is also possible to synthesize esters and polymers. In the synthesis of organic substances such as alcohols, acids, hydrocarbons, etc., the hydrogenation reaction involving C0 ₂ needs to be provided from outside the system.

2. Option 2

In the first scheme, air is used to burn coal, and the air introduction system is 21 parts 0 ₂ , accompanied by the necessity to introduce 79 to play N ₂ . N ₂ does not participate in the reaction from the beginning to the end of the system. After the combustion process is completed, N2 is present in the flue gas, still occupying the flue gas. 80% of the volume, it takes about 80% of the volume of the gas to consume energy. When leaving the coal-fired boiler, it takes away the heat. It takes energy to remove the heat from the system. C0 ₂ is diluted by N ₂ and is given to it. The C0 ₂ purification brings a lot of trouble. If the air introduced into the system is changed to oxygen-enriched gas or pure oxygen, the situation will be greatly improved. For example, containing ₀₂ to 80% to the oxygen-rich coal, coal gas amount is only 1/4 of the air, the total energy consumption of air is only 1/4 of coal. The significant reduction in energy consumption has laid the foundation for the realization of this technology.

The difference between Scheme 2 and Scheme 1 is to increase the air separation process. The use of air to burn coal is to burn coal with oxy-enriched gas. The other processes are unchanged, as shown in Figure 3.

"Oxygen-rich preparation":

"Oxygen enrichment" is a gas with a high oxygen content, and its oxygen content is much higher than the oxygen content of 21% in the air. When its oxygen content is close to 100%, it is called "pure oxygen". "Oxygen-enriched" and "pure oxygen" are produced by air separation. Usually, air separation is carried out by physical methods, including cryogenic distillation, pressure swing adsorption and membrane separation techniques. Low temperature distillation due to large equipment, high energy consumption, separation The effect is poor, so the cost is high, but according to the requirements, "oxygen enrichment", "pure oxygen" and "pure nitrogen" can be obtained; the pressure swing adsorption process is simple in process, low in energy consumption, strong in adaptability, high in automation, and low in cost. Low; Membrane separation method is simple, easy to operate, low energy consumption, but it is difficult to obtain high purity gas, suitable for "oxygen enrichment", and not suitable for "pure oxygen". Here, it is preferred to produce an oxygen-rich gas having an oxygen content of 80 to 90% by selective pressure swing adsorption.

Oxygen enrichment is obtained by air separation, while pure N ₂ and rare gases are produced.

S Burning coal:

Oxygen-enriched coal is a process in which fuel coal is burned in an oxygen-rich gas to release energy in the form of light and heat. This oxygen-rich gas is obtained by separating the air, and its oxygen content is much higher than 21% in the air. ₀ Considering the oxygen content of the oxygen-enriched gas used in the oxygen-enriched combustion coal is preferably 80% - 90%. Oxygen-enriched combustion coal is very different from air-burning coal because of the large difference in oxygen content between oxygen-enriched air and air.

During the combustion of coal, due to the increase of oxygen content, the reaction between oxygen and coal becomes fierce, which strengthens the combustion of coal; the increase of oxygen content reduces the amount of smoke before and after combustion.

Oxygen-enriched coal combustion, like air-burning coal, needs to be carried out in a furnace. The change in the combustion state of the boiler in order to adapt to the increase in oxygen content has to be greatly changed.

The outstanding feature of oxy-combustion coal is to strengthen the combustion of coal, creating conditions for the purification of flue gas and the recycling of carbon dioxide.

3. Scheme 3

Both Scheme 1 and Scheme 2 involve organic synthesis. One of the main contents of organic synthesis is addition, which requires 3⁄4 sources. The integration of the source of the solution into the system of the program will be another picture. It is worth noting that when solving the source of 3⁄4, it is forbidden to use fossil fuels such as coal, petroleum, natural gas, etc., because when these fuels are used as the starting materials, it is necessary to produce an equivalent amount of co _{2 to} solve the problem. These co ₂ problems are obviously meaningless. The scheme adopts the method of electrolyzing water, and provides the required 0 ₂ for the oxy-combusted combustion coal while providing the organic synthesis, and does not need external supply of the system, thus forming the scheme 3. As shown in Figure 4.

The difference between Scheme 3 and Scheme 2 is that instead of air separation with electrolyzed water, it provides 3⁄4 for organic synthesis while providing the 0 ₂ required for oxyfuel combustion.

4. Scheme 4

The second scheme is applied to the original air-fired boiler. The combustion chamber and boiler tube of the original boiler are not adapted to the new changes. In order to adapt the original facilities to the new change of "oxygen-enriched coal", from "C0 ₂ purification""After extracting a pure C0 ₂ gas instead of N ₂ in the original air, adding it to "enriched oxygen", keeping the 0 ₂ content in the furnace gas as 21% as air, other processes The same as program one, the fourth option is formed. As shown in Figure 5. Although the process indicators will change, it does not affect the normal operation of the boiler.

Claims

Rights request

1. A non-polluting technology for comprehensive treatment of coal-fired boilers, characterized in that: the technology includes: "air separation system 0 ₂ ", "electrolyzed water system, 0 ₂ ", "fired boiler", "dust removal"","Molecular Sieve Manufacturing", "Fume Purification", "C0 ₂ Purification", "Slow Release C0 ₂ Gas Fertilizer Preparation", "C0 ₂ Utilization" Combination Process; Burning Coal Contact: Li Shuzu Slow release C0 ₂ gas fertilizer, all returning to nature in the shape of fertilizer, realizing non-polluting discharge of coal-fired boiler 2, non-polluting emission technology according to claim 1, characterized in that: "Boiler", in addition to the usual air-fired boiler, also includes an oxygen-enriched coal-fired boiler; the difference between the oxygen-enriched coal-fired boiler and the usual air-fired boiler is that the gas fed to the boiler is not air but oxygen-rich gas. The oxygen content of the oxygen-enriched gas in the furnace is >21%; it is generally considered to be 80% - 90%; the oxygen enrichment required for oxyfuel combustion is obtained by separating or electrolyzing water.

3. The pollutant-free discharge technology according to claim 1, wherein: said coal ash slag molecular sieve is a molecular sieve made of ash produced by burning coal as a main raw material, and the molecular sieve is equivalent In Type 4A, the preparation method is as follows:

(1) The cinder is ground to 150 mesh, mixed with fly ash to form a coal-fired ash mixture powder, and Al (OH) ₃ and Na ₂ C0 ₃ or NaOH are baked at 120 ° C for 2-3 Hours, remove moisture, then mix well;

(2) calcining at a temperature of 800-85 CTC for 1-1. 5 hours, and then pulverizing after forming a light green material;

(3) Under stirring, the pulverized material is put into water, heated to 50-55 ° C, and kept at a constant temperature for 2 hours, and the alkalinity is taken for analysis, and the total alkalinity is added to 1 N;

(4) heating to 98 ° C, crystallization for 6 hours under stirring;

(6) Instead of Na ₂ C0 ₃ (or NaOH), K ₂ C0 ₃ (or K0H) may be used as needed.

4. The technology according to claim 1, wherein: the sustained release CO ₂ gas fertilizer is prepared in a dry state, and the pure CO ₂ gas passes through the coal ash slag molecular sieve bed to burn coal. The ash slag molecular sieve fully adsorbs the co ₂ gas and becomes a "slow release co ₂ gas fertilizer", and the sustained release (0 ₂ gas fertilizer is stored under moisture tightness under closed conditions;

In order to reduce the accumulation of Na ions, in the preparation of coal ash slag molecular sieves, the K salt (or K base) is used instead of the Na salt (or Na base). 5. The pollutant-free discharge technology according to claim 1, wherein: the coal can be burned with oxygen-enriched gas in an air-fired boiler, as long as the flue gas is returned to a part and mixed with the oxygen-rich gas into the furnace. , the oxygen content of the furnace mixture can be maintained at 21%, and the air-fired boiler does not need to be changed.