Blending combustion method of coal and gasified slag in circulating fluidized bed boiler

Abstract

The invention provides a blending combustion method for coal and gasified slag in a circulating fluidized bed boiler, and belongs to the technical field of energy engineering. According to the blending combustion scheme provided by the invention, by adopting the specific blending combustion materials and additives, the optimal boiler blending combustion efficiency can be obtained, so that the energy consumption is reduced, the operation cost is reduced, and energy conservation, emission reduction and environmental protection are facilitated; the special selection and proportion of the blending combustion materials can significantly improve the desulfurization rate in the blending combustion process of the circulating fluidized bed boiler, and the method has important significance on environmental protection, energy utilization efficiency, sustainable development, technical innovation and health benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of energy engineering, and particularly to a method for co-firing coal and gasification slag in a circulating fluidized bed boiler. Background Art

[0002] Circulating fluidized bed boilers adopt the clean coal combustion technology with the highest industrialization degree. Circulating fluidized bed boilers use fluidized bed combustion, and their main structures include two major parts: a combustion chamber (including a dense phase zone and a dilute phase zone) and a circulating return furnace (including a high-temperature gas-solid separator and a return system). The biggest difference from the bubbling fluidized bed combustion technology is the high operating wind speed, which strengthens the heterogeneous reaction processes such as combustion and desulfurization. The boiler capacity can be expanded to a large capacity acceptable to the power industry (600 MW or above). Circulating fluidized bed boilers have well solved basic problems such as thermotics, mechanics, and materials science, as well as engineering problems such as expansion, wear, and overheating, and have become an advanced technology for the energy utilization of difficult-to-burn solid fuels (such as coal gangue, oil shale, municipal solid waste, sludge, and other waste materials).

[0003] In order to maintain energy security and meet the requirements of environmental protection, as one of the important means of clean coal utilization, coal-to-liquid technology has received great attention and development. However, this technology is also an important source of waste residue generation. In the prior art, a large amount of ash slag is generated every year in the coal refining to oil project, mainly from gasification slag and boiler ash slag, accounting for 95% and 5% of the total slag production respectively. In addition, a large amount of ash slag substances are discharged during the gasification process, which not only occupies a large amount of land area for storage, but also causes consequences such as soil and water body pollution. Therefore, studying the resource utilization technology of gasification slag is the key to reducing the treatment cost of gasification slag and improving economic and environmental benefits.

[0004] Agricultural and forestry residues refer to the waste materials and garbage generated during the harvesting and processing of agricultural and forestry crops, including a large amount of agricultural and forestry food processing residues. It is an important biomass resource with a large quantity waiting to be developed and utilized. Common ones include: straw and rice husk remaining after crop harvesting, bagasse, bamboo shoots and bamboo husks remaining after processing of cash crops, mushroom bran and mushroom heads remaining after mushroom production, as well as wood processing residues and forest logging residues, etc. The resource utilization of agricultural and forestry residues is of great significance.

[0005] Currently, no technical solution has been seen that can realize the resource utilization of gasification slag and agricultural and forestry residues while improving the working efficiency of circulating fluidized bed boilers. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for co-firing coal and gasification slag in a circulating fluidized bed boiler, which can reduce energy consumption and reduce the emission of harmful substances.

[0007] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for co-firing coal and gasification slag in a circulating fluidized bed boiler, comprising the following steps:

[0009] Mix the main co-firing material with an additive and feed it into the circulating fluidized bed boiler for co-firing;

[0010] The main co-firing material contains coal, gasification slag, coal tar pitch flakes, agricultural and forestry residues, and graphite powder.

[0011] Preferably, the additive contains castor oil polyoxyethylene ether, a surfactant, and nitroguanidine.

[0012] Preferably, by weight, the main co-firing material contains the following raw materials:

[0013] 80 - 120 parts of coal, 75 - 85 parts of gasification slag, 10 - 30 parts of coal tar pitch flakes, 10 - 30 parts of agricultural and forestry residues, and 10 - 30 parts of graphite powder.

[0014] Preferably, by weight, the additive contains the following raw materials:

[0015] 0.8 - 1.2 parts of castor oil polyoxyethylene ether, 1.8 - 2.2 parts of surfactant, and 1.3 - 1.8 parts of nitroguanidine.

[0016] Preferably, the coal is bituminous coal.

[0017] Preferably, the agricultural and forestry residues are selected from one or more of forestry residues, waste wood, wood chips, crop straws, rice husks, wheat bran, or rice bran.

[0018] Preferably, the crop straws are from wheat, rice, corn, tubers, rapeseed, cotton, or sugarcane.

[0019] Preferably, the surfactant is a non-ionic surfactant.

[0020] Preferably, the non-ionic surfactant is selected from one or more of fatty acid glycerides, sucrose fatty acid esters, sorbitan fatty acids, polysorbates, polyoxyethylene fatty acid esters, polyoxyethylene fatty alcohol ethers, and polyoxyethylene-polyoxypropylene polymers.

[0021] The present invention provides the application of the above-mentioned method for co-firing coal and gasification slag in a circulating fluidized bed boiler in improving combustion efficiency or desulfurization efficiency.

[0022] The technical effects and advantages of the present invention:

[0023] The co-firing solution provided by the present invention can achieve the optimal co-firing efficiency of the boiler by using specific co-firing materials and additives, thereby reducing energy consumption, lowering operating costs, and contributing to energy conservation, emission reduction, and environmental protection. The special selection and proportion of the co-firing materials in the present invention can significantly improve the desulfurization rate in the co-firing process of circulating fluidized bed boilers, which is of great significance for environmental protection, energy utilization efficiency, sustainable development, technological innovation, and health benefits. Detailed Embodiment

[0024] The present invention provides a method for co-firing coal and gasification slag in a circulating fluidized bed boiler, comprising the following steps:

[0025] Mix the main co-firing material with the additive and feed it into the circulating fluidized bed boiler for co-firing;

[0026] The main co-firing material contains coal, gasification slag, coal tar pitch flakes, agricultural and forestry residues, and graphite powder.

[0027] In the present invention, preferably, by weight, the main co-firing material contains the following raw materials: 80 - 120 parts of coal, 75 - 85 parts of gasification slag, 10 - 30 parts of coal tar pitch flakes, 10 - 30 parts of agricultural and forestry residues, and 10 - 30 parts of graphite powder.

[0028] In the present invention, preferably, the coal is bituminous coal.

[0029] In the present invention, the agricultural and forestry residues are an important member of waste and an important biomass resource. The agricultural and forestry residues in the present invention are preferably selected from one or more of forestry residues, waste wood, wood chips, crop straws, rice husks, wheat bran, or rice bran; further preferably, the crop straws are from wheat, rice, corn, tubers, rapeseed, cotton, or sugarcane.

[0030] In the present invention, the additive contains castor oil polyoxyethylene ether, surfactant, and nitroguanidine; preferably, by weight, the additive contains the following raw materials: 0.8 - 1.2 parts of castor oil polyoxyethylene ether, 1.8 - 2.2 parts of surfactant, and 1.3 - 1.8 parts of nitroguanidine; in the present invention, by combining these three components of castor oil polyoxyethylene ether, surfactant, and nitroguanidine, a synergistic effect can be achieved, thereby significantly improving the combustion-supporting performance of coal. This unique combination can effectively promote the combustion process of coal, making the coal burn more fully, thereby further increasing the calorific value of the material during combustion. In this way, not only can the combustion efficiency be improved, but also the economic benefits can be significantly enhanced. Specifically, this combination can reduce the consumption of coal, reduce the emission of harmful gases, and at the same time improve the utilization rate of thermal energy, thereby bringing economic benefits to the industry in multiple aspects.

[0031] In the present invention, preferably, the surfactant is a non-ionic surfactant; preferably, the non-ionic surfactant is selected from one or more of fatty acid glycerides, sucrose fatty acid esters, sorbitan fatty acids, polysorbates, polyoxyethylene fatty acid esters, polyoxyethylene fatty alcohol ethers, and polyoxyethylene-polyoxypropylene polymers.

[0032] Among the non-ionic surfactants of the present invention, the fatty acid glycerides are mainly fatty acid monoglycerides and fatty acid diglycerides, such as glycerol monostearate, etc. They are insoluble in water, easily hydrolyzed into glycerol and fatty acids, have weak surface activity, an HLB value of 3-4, and are often used as W / O type auxiliary emulsifiers; the sucrose fatty acid esters, abbreviated as sucrose esters, belong to polyol type non-ionic surfactants, which are a class of compounds formed by the reaction of sucrose and fatty acids, including monoesters, diesters, triesters, and polyesters. They can be decomposed into sucrose and fatty acids in the body and utilized. The HLB value is 5-13, and they are often used as O / W type emulsifiers and dispersants. The sorbitan fatty acids are sorbitan fatty acid esters, which are a mixture of ester compounds obtained by the reaction of sorbitol anhydride and its anhydride with fatty acids, and the trade name is Span; the polysorbates are polyoxyethylene sorbitan fatty acid esters. They are ether compounds obtained by further bonding a polyoxyethylene group to the remaining -OH on the Span type, and the trade name is Tween. Due to the addition of the hydrophilic polyoxyethylene group, the hydrophilicity is greatly increased, and it becomes a water-soluble surfactant. The HLB value is 9.6-16.7, and it is often used as a solubilizer and O / W type emulsifier; the polyoxyethylene fatty acid esters are esters formed by the condensation of polyethylene glycol and long-chain fatty acids, and Myrij is one of the trade names, which is water-soluble and has strong emulsifying performance, and is often used as an O / W type emulsifier and solubilizer; the polyoxyethylene fatty alcohol ethers are ethers formed by the condensation of polyethylene glycol and fatty acids, and Brij is one of the trade names. It is often used as an O / W type emulsifier and solubilizer; the polyoxyethylene-polyoxypropylene polymer is formed by the polymerization of polyoxyethylene and polyoxypropylene, also known as Poloxamer, and the trade name is Pluronic. Theoretically, the above non-ionic surfactants can all be used in the co-combustion method of the present invention, and Tween 80 is used in a specific embodiment of the present invention.

[0033] In the present invention, other combustion aids can also be added during the co-combustion process, including:

[0034] 1. Mainly using intensifiers or supplemented with industrial salts, MnO 2 , Fe 2 O 3, sugar, urea, phosphorus and antimony trisulfide, supplemented with a sulfur-fixing agent. Such combustion aids have a certain effect on reducing the ignition point of the fuel and promoting combustion. However, this kind of quick-burning oxidant is unstable, decomposes rapidly when heated, and has a short action time on the combustion system. In addition, there are relatively large potential safety hazards during the processing, transportation and storage of strong oxidants.

[0035] 2. Mainly various metal oxides and tailings. During use, the metal ions have a certain particle size and must undergo drying, decomposition, and diffusion before they can take effect. The combustion of coal is a rapid reaction, while the catalytic cracking reaction expected by metal ions is a slow reaction and must go through processes such as adsorption, complexation, cracking, and desorption, so its effect is not timely.

[0036] 3. Mainly organic molecules. Organic alcohols: For example, the one adopted in Chinese Patent CN 1266089A is prepared from methanol, ethanol, Tween, Span and its distilled water in a certain ratio. Secondly, commonly used organic solvents such as plant enzymes, ether, acetone, and ethyl acetate are used, such as Chinese Patent CN 1405283A. Thirdly, combustion aids with lipophilic mineral oil, lipophilic vegetable oil, emulsifier and hydrophilic surfactant as the main materials are used. A certain patent mainly uses surface active catalysts, dissolution aids, penetrants and oily solvents. A new type of high-efficiency coal combustion catalyst compounded from alkyl alcohol ethers, alkyl esters, phosphate esters, alkyl alcohol amides, olefins and aromatic compounds can achieve the triple results of coal saving, emission reduction and coke removal in boilers without boiler modification.

[0037] 4. Mainly metal carboxylates, including organic carboxylates such as acetates, succinates, and fatty acid salts. For example, Chinese Patent CN 1718699A uses main raw materials such as acetate oxalate, acetate, oxalate, succinate, fatty acid salt, alkyl sulfonate, alkyl benzene sulfonate, aminosulfonate, maleate, fumarate, citrate, tartrate, tannate, lactate, hydroxy acid salt, benzoate, naphthenate, isooctanoate, copper trimethylacetyltriketone ester, methylcyclopentadienyl tricarboxyl manganese, etc. Such metal carboxylates are not very stable and are prone to inactivation by forming salts or oxides during the combustion process. The reaction of metal ions is similar to that of the combustion aids in the second category.

[0038] The present invention provides an application of the co-combustion method of coal and gasification slag in the above circulating fluidized bed boiler in improving the combustion efficiency or desulfurization efficiency.

[0039] The circulating fluidized bed boiler of the present invention preferably adopts a single-drum, natural circulation mode, and is generally divided into two vertical shafts, namely the front shaft and the rear shaft. The front vertical shaft is of a total suspension structure and is composed of membrane water walls on all sides. From bottom to top, there are a primary air chamber, a dense phase zone, and a dilute phase zone in sequence. The flue gas duct at the rear part is, from top to bottom, a high-temperature superheater, a low-temperature superheater, an economizer, and an air preheater in sequence. The rear vertical shaft adopts a support structure, and the two vertical shafts are connected by a vertical cyclone separator. The lower part of the separator is connected to a return device and an ash cooler. Anti-abrasion linings are provided inside both the combustion chamber and the separator. The front vertical shaft uses a tube-supported furnace wall with an external metal guard plate, and the rear vertical shaft uses a light furnace wall. All the weights of the boiler are borne by eight steel columns.

[0040] Although the existing circulating fluidized bed boilers have some remarkable advantages, such as high combustion efficiency, strong fuel adaptability, and low pollutant emissions, there is still room for improvement in terms of co-firing raw materials. To achieve better effects, we need to further optimize the processes and methods of co-firing raw materials. Specifically, the pretreatment technology of raw materials can be improved to enhance the uniformity and combustion performance of raw materials, thereby improving the overall operation efficiency of the boiler. In addition, new co-firing formulations can be studied and developed, combining the characteristics of different fuels, to achieve the best combustion effect and environmental protection standards. Through these improvement measures, circulating fluidized bed boilers will be able to better meet the needs of industrial production and environmental protection in future applications.

[0041] In the present invention, we have made in-depth improvements and optimizations to the many advantages of circulating fluidized bed boilers. By combining the unique co-firing scheme proposed in the present invention, the best combustion efficiency can be achieved while ensuring high-efficiency desulfurization. This innovation is not only of great significance to environmental protection because it can significantly reduce the emissions of harmful gases, but also plays a key role in improving energy utilization efficiency. In this way, we can make more effective use of limited resources, thus promoting the process of sustainable development. In addition, the present invention has also made important contributions to technological innovation because it has introduced new methods and ideas, providing new directions for the development of related fields. The present invention also has a positive impact on health benefits because it improves air quality by reducing pollutant emissions, thus having a positive promoting effect on public health.

[0042] In the present invention, the usage ratio of the co-firing materials and additives can be adjusted according to actual combustion conditions and the required combustion efficiency to achieve the best combustion and desulfurization effects; the method also includes real-time monitoring and optimization of the co-firing process to ensure the full combustion of the co-firing materials and the effective control of pollutants; the real-time monitoring includes, but is not limited to, the monitoring of combustion temperature, oxygen concentration, combustion product composition, and emissions; the optimization measures include, but are not limited to, adjusting the air volume, temperature in the combustion chamber, and the feeding sequence of materials to achieve the best combustion efficiency and pollutant emission control.

[0043] The co-firing scheme proposed by the present invention can achieve the best boiler co-firing efficiency by carefully selecting specific co-firing materials and reasonably adding corresponding additives. This optimized co-firing method can not only significantly reduce energy consumption, thereby reducing the operating costs of enterprises, but also has a positive promoting effect on energy conservation, emission reduction and environmental protection. Specifically, the special selection of co-firing materials and their precise proportioning in the present invention can significantly improve the desulfurization efficiency of circulating fluidized bed boilers in the co-firing process. This technological progress has far-reaching significance for environmental protection, improvement of energy utilization efficiency, promotion of sustainable development, and enhancement of technological innovation and health benefits. In this way, we can not only achieve economic benefits, but also contribute to the sustainable development of society and environmental protection.

[0044] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Types of raw materials used in the embodiments of the present invention:

[0046] Coal: bituminous coal;

[0047] Composition of gasification slag: 50% coarse slag, 50% fine slag.

[0048] Example 1

[0049] 100 parts of bituminous coal, 80 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 10 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 2 parts of Tween 80 and 1.5 parts of nitroguanidine are premixed evenly and put into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co-firing;

[0050] The boiler efficiency is directly calculated through the input and output parameters of the boiler, and the result is 89.56%; the flue gas flow rate is recorded as 389.31 kg / s, and the desulfurization rate is calculated as 93.27%.

[0051] Example 2

[0052] 100 parts of bituminous coal, 75 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 8 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 2 parts of Tween 80 and 1.5 parts of nitroguanidine are premixed evenly and put into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co-firing;

[0053] The boiler efficiency is directly calculated through the input and output parameters of the boiler, and the result is 89.34%; the flue gas flow rate is recorded as 387.33 kg / s, and the desulfurization rate is calculated as 93.15%.

[0054] Example 3

[0055] 100 parts of bituminous coal, 85 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 12 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 2 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0056] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.18%, the flue gas flow rate is recorded as 392.24 kg / s, and the desulfurization rate is calculated as 93.69%.

[0057] Example 4

[0058] 100 parts of bituminous coal, 90 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 8 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 1.8 parts of Tween 80, and 1.3 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0059] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.90%, the flue gas flow rate is recorded as 388.77 kg / s, and the desulfurization rate is calculated as 93.26%.

[0060] Example 5

[0061] 100 parts of bituminous coal, 80 parts of gasification slag, 22 parts of coal tar pitch flakes, 20 parts of rice husk, 10 parts of graphite powder, 1.2 parts of castor oil polyoxyethylene ether, 2.2 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0062] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.11%, the flue gas flow rate is recorded as 394.00 kg / s, and the desulfurization rate is calculated as 93.52%.

[0063] Example 6

[0064] 100 parts of bituminous coal, 80 parts of gasification slag, 18 parts of coal tar pitch flakes, 20 parts of rice husk, 10 parts of graphite powder, 0.8 part of castor oil polyoxyethylene ether, 2 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0065] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.67%, the flue gas flow rate is recorded as 385.62 kg / s, and the desulfurization rate is calculated as 93.39%.

[0066] Example 7

[0067] 100 parts of bituminous coal, 80 parts of gasification slag, 20 parts of coal tar pitch flakes, 18 parts of rice husk, 10 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 2 parts of Tween 80, and 1.8 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0068] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.28%, the flue gas flow rate is recorded as 381.36 kg / s, and the desulfurization rate is calculated as 93.13%.

[0069] Example 8

[0070] 100 parts of bituminous coal, 80 parts of gasification slag, 20 parts of coal tar pitch flakes, 22 parts of rice husk, 10 parts of graphite powder, 0.8 part of castor oil polyoxyethylene ether, 2 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0071] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.09%, the flue gas flow rate is recorded as 390.12 kg / s, and the desulfurization rate is calculated as 93.54%.

[0072] Example 9

[0073] 100 parts of bituminous coal, 80 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 12 parts of graphite powder, 1.2 parts of castor oil polyoxyethylene ether, 1.8 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0074] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 89.07%, the flue gas flow rate is recorded as 380.11 kg / s, and the desulfurization rate is calculated as 93.48%.

[0075] Example 10

[0076] 100 parts of bituminous coal, 80 parts of gasification slag, 20 parts of coal tar pitch flakes, 20 parts of rice husk, 8 parts of graphite powder, 1 part of castor oil polyoxyethylene ether, 2 parts of Tween 80, and 1.5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20 - 2.4 - M.Z) reactor for co - firing;

[0077] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 90.42%, the flue gas flow rate is recorded as 385.70 kg / s, and the desulfurization rate is calculated as 93.06%.

[0078] Comparative Example 1

[0079] 100 parts of bituminous coal and 80 parts of gasification slag are premixed evenly and fed into a circulating fluidized bed (DHX20-2.4-M.Z) reactor for co-combustion;

[0080] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 80.58%, the flue gas flow rate is recorded as 327.05 kg / s, and the desulfurization rate is calculated as 70.29%.

[0081] Comparative Example 2

[0082] 100 parts of bituminous coal, 80 parts of gasification slag, 1.7 parts of castor oil polyoxyethylene ether, 1.5 parts of Tween 80, and 1.3 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20-2.4-M.Z) reactor for co-combustion;

[0083] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 82.10%, the flue gas flow rate is recorded as 322.45 kg / s, and the desulfurization rate is calculated as 73.15%.

[0084] Comparative Example 3

[0085] 100 parts of bituminous coal, 80 parts of gasification slag, 25 parts of coal tar flakes, 25 parts of rice husk, 3 parts of castor oil polyoxyethylene ether, 4 parts of Tween 80, and 5 parts of nitroguanidine are premixed evenly and fed into a circulating fluidized bed (DHX20-2.4-M.Z) reactor for co-combustion;

[0086] The boiler efficiency is directly calculated through the input and output parameters of the boiler. The result is 82.09%, the flue gas flow rate is recorded as 324.08 kg / s, and the desulfurization rate is calculated as 81.13%.

[0087] It can be seen from the above examples that the co-combustion scheme provided by the present invention can obtain the optimal boiler co-combustion efficiency, thereby reducing energy consumption, lowering operating costs, and contributing to energy conservation, emission reduction, and environmental protection; the special selection and proportion of the co-combustion materials of the present invention can significantly improve the desulfurization rate in the circulating fluidized bed co-combustion process, which is of great significance for environmental protection, energy utilization efficiency, sustainable development, technological innovation, and health benefits.

[0088] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for mixing coal and gasification slag in a circulating fluidized bed boiler, characterized in that: The following steps are involved: The main material for blending is mixed with the additive and put into a circulating fluidized bed boiler for blending; The main materials for the mixed combustion contain coal, gasified slag, coal tar pitch flakes, agricultural and forestry residues and graphite powder.

2. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 1, characterized in that: The additive contains castor oil polyoxyethylene ether, a surfactant and nitric acid urea.

3. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 1, characterized in that: The main blended material contains the following raw materials in parts by weight: 80-120 parts of coal, 75-85 parts of gasification slag, 10-30 parts of coal tar flakes, 10-30 parts of agricultural and forestry residues and 10-30 parts of graphite powder.

4. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 2, characterized in that: The additive contains the following raw materials in parts by weight: 0.8-1.2 parts of castor oil polyoxyethylene ether, 1.8-2.2 parts of surfactant and 1.3-1.8 parts of nitric acid urea.

5. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 1, characterized in that: The coal is bituminous coal.

6. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 1, characterized in that: The agricultural and forestry residues are selected from one or more of forestry residues, waste wood, wood chips, crop straws, rice husks, bran or rice bran.

7. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 6, characterized in that: The crop straws are from wheat, rice, corn, potatoes, rapeseed, cotton or sugarcane.

8. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 2 or 4, characterized in that: The surfactant is a nonionic surfactant.

9. The method for blending coal and gasified slag in a circulating fluidized bed boiler according to claim 8, characterized in that: The nonionic surfactant is selected from one or more of fatty acid glycerides, sucrose fatty acid esters, fatty acid sorbitan, polysorbate, polyoxyethylene fatty acid esters, polyoxyethylene fatty alcohol ethers and polyoxyethylene-polyoxypropylene polymers.

10. Use of the method for blending coal and gasification slag in a circulating fluidized bed boiler as claimed in any one of claims 1 to 9 in improving combustion efficiency or desulfurization efficiency.