Ⅰ.Design of Production Process for Preparing System of Ultra-fine Powder Production Line

After cleaning, the high-quality and high-whiteness calcite raw materials, which were crushed and screened, were subjected to secondary crushing, and the particle size of the crushed calcite was less than 3-6 mm. Then the hoist is fed into the feeding bin, and the raw material is fed into the high-fine ball mill for grinding by metering. The grinding powder is fed into the hoist by air separation. Under the action of pneumatic suction, the powder is classified into the classifier for particle size classification. The product fineness is 600-3000 mesh and can be adjusted arbitrarily. The qualified fine powder is carried into the special high-pressure pulse bag dust collector by air flow, and the finished product is collected and sent to the storage. The coarse powder separated from the classifier is then sent to the ball mill for grinding. The whole system forms a closed-circuit cycle processing system.

If the product fineness needs to be improved, the separation process steps can be increased many times to produce products with higher fineness.

The production system is operated under negative pressure, and dust collectors are set at dust-raising points of material conversion to prevent dust-raising.

The system equipment adopts advanced DCS control operation, which can control the operation of the whole production system in the central control room and improve the working environment of operators.

Ultrafine powder grinding system

Ⅱ.Main technical characteristics of the preparation system of ultra-fine powder production line

ⅰ.Dry Ball Milling Technology

1. Special design was adopted to optimize the length-diameter ratio of ball mill and improve the grinding efficiency.
2. The grinding fineness of the product is improved by using a scientific graded grinding medium.
3. Drive bearing adopts rolling bearing + dry oil lubrication mode, which simplifies the lean oil lubrication station and reduces the operation cost.
4. The product fineness can reach 3000 meshes by pure dry method.
5. Advantages of the product: narrow particle size distribution, continuous and stable batch. Particles are spherical, with large specific surface area, good filling effect and refractive effect, which can meet the requirements of high-end users.

ii.Fine air classification technology

By using multi-level grader and grading process combination, products of different fineness levels are separated to meet the needs of different customers. The classification efficiency of the developed multi-rotor classifier can reach 90%.

The one-time grading fineness can be adjusted in 325-3000 meshes. Adding the secondary classification system can reach the advanced level of dry ultrafine powder classification at home and abroad.

ⅲ.Ultra low emission

The production line layout is compact and reasonable, and the production system operates under negative pressure without dust leakage to meet the emission requirements.

ⅳ.DCS control technology is adopted in production system

The whole production system adopts one-key DCS central control system to realize intelligent production process control from crushing, grinding, grading, storage, packaging, loading and transportation, which ensures real-time production monitoring, ensures the continuous stability of the system, the stability and reliability of product quality, and reduces production costs.

Ⅲ.Technical Advantages of Preparing System for Ultrafine Powder Production Line

1. High efficiency and energy saving: high grinding and flour separation efficiency, high product fineness;
2. The process is smooth and simple: easy maintenance and low operation cost;
3. Green environmental protection: dust and noise emission up to standard;
4. Continuous stability, excellent quality: product quality is stable, annual continuous operation time can reach 300 days;
5. High performance-price ratio: low cost of comprehensive investment;
6. High degree of automation: DCS automatic control of production process;
7. Advanced technology and equipment: The advanced technology and equipment at home and abroad are adopted, and the equipment is stable and reliable.

Luoyang Building Materials Architectural Design Research Institute (LCDRI) is a state-level high-tech enterprise specializing in industrial equipment research and development and mineral material production technology services. The company has core technology in cement building material production line, fine powder (slag) production line, active lime production line, solid waste treatment, soil (sludge) environmental protection treatment, oil shale comprehensive utilization, sludge comprehensive treatment and so on.

The main difference between active lime and ordinary lime is the activity of lime. When steel mill smelts steel, adding active lime can greatly improve the smelting efficiency of steel. In view of the increasing demand for active lime in the market and the large gap in the market, lime production enterprises gradually begin to adopt professional lime kilns and processes to produce active lime. But in the process of active lime production, there are many problems one after another. If these problems can not be solved in time, the quality of active lime will be greatly affected. Let’s understand the production process of active lime and some problems needing attention in the calcination process, and reveal some unknown secrets in the process of active lime production for you.

The raw materials used for producing active lime are mainly carbonate rocks. The element composition is mainly CaCO3, which is what we usually call limestone. There are many kinds of limestone, such as granular crystalline limestone, compact limestone, porous limestone, earthy limestone, marl limestone, chalk, dolomite, shell limestone River pebble and so on. Because of the high requirement of calcium oxide content in the main chemical composition of active lime, it should generally reach more than 90%. At the same time, the lower the content of sulfur, phosphorus and other impurities, the better the requirements.

Therefore, the quality of raw limestone for the production of active lime is clearly required. In the selection and use of lime raw materials, among many grade limestone, limestone with calcium oxide content greater than 54%, low impurity content such as silicon dioxide, sulfur, phosphorus, magnesium oxide, ferric oxide and aluminium oxide is often used as raw material for calcining active lime. Because it is the primary guarantee to realize the physical and chemical properties of active lime products, this is very important.

The influence of calcining equipment on lime activity depends largely on the calcining equipment used for calcining limestone. According to the structure of the kiln, the lime kiln can be roughly divided into ordinary shaft kiln, parallel flow regenerative shaft kiln, sleeve shaft kiln, rotary kiln and fluidized bed kiln.

Common shaft kiln can not produce high active lime because of the following reasons: 1) uneven distribution of air flow in the cross section of shaft kiln, different speed of material moving downward, large temperature difference on the same cross section, forming local high-temperature zone and low-temperature zone, resulting in uneven calcination degree of lime and poor activity of lime; 2) long residence time of limestone in kiln, generally about 20-45 hours, resulting in rearrangement of lime crystal lattices and increase of grain size. As a result, inactive lime with low reactivity is produced. 3. Coke and coal are commonly used as raw materials in lime shaft kilns in China, because ash generated by coke and coal residues in lime, resulting in an increase in lime impurities.

Rotary kiln can forge lime with high activity. The reasons are as follows: 1. Radiation heat transfer is the main heat transfer in the rotary volume, while conduction heat transfer is the main heat transfer in the lime layer. Through the continuous rotation of the kiln body, the material is continuously mixed and homogenized. During the rolling process, the large particles in the upper layer of the material and the small particles in the lower part of the material layer are uniformly heated to produce limestone with uniform quality and high activity. Secondly, the calcination of limestone is carried out from the surface to the inside, and the space temperature of the kiln increases with the increase of the calcination temperature, but the temperature dimension of the material layer in the kiln is uniform. When limestone is fired into lime, the temperature will rise sharply, resulting in over-burning, so lime must be quickly pushed out from the kiln. The material of rotary kiln stays in the kiln for a short time, which can meet the technological requirements of producing active lime.

Activated lime Suspension Calcination has high yield and high quality. The reasons are as follows: 1) grinding limestone, because limestone usually has good grindability, low grinding cost, makes full use of limestone resources; 2) using suspension calcination production technology, heat transfer efficiency is greatly improved, heat consumption is reduced and power consumption is reduced. Hudao and Professor of Nanjing Institute of Chemical Technology have done experiments and concluded that: in the case of material accumulation and suspension, the decomposition time can be 40-80 times different; (3) the automation of production control can be easily realized; (4) the production scale can be allocated according to user’s needs, and the single-line daily output can achieve 300-5000 tons of different scales; (5) the fuel can use gas, oil, coal and so on; (5) the area occupied by the rotary kiln production system. Reduction of 60%; _Emission fully meets the current emission standards in China; _Investment is equivalent to 25%-30% of the rotary kiln production system; _Product activity is comparable to that of rotary kiln products; _Heat consumption can be controlled at 800-1000 kcal/kg.

The active lime suspension calcination production line developed by Luoyang Building Material Architectural Design Research Institute adopts the preheater decomposition process used in the traditional cement industry. At present, this process is the first one in China and has obtained relevant patent certificates. It can avoid traditional kiln completely and effectively by using mature experience of cement design and construction and flexibly in the production of active lime. There are many inconveniences and shortcomings brought about by production.

Domestic garbage gasification is the dream of garbage disposal industry. Compared with traditional garbage incineration, garbage gasification has no emissions of ash and dioxins. Compared with the past landfill, it will not occupy land, and will not cause soil and groundwater pollution.

I. Current Status of Domestic Waste Treatment

In terms of waste disposal methods, sanitary landfill, direct incineration and organic compost were the main disposal methods in China before. Landfill was the main disposal method, accounting for 50%, incineration 12%, compost less than 10%, and nearly 30% of domestic waste had not yet been disposed of.
Landfill and incineration have always been traditional ways of garbage disposal, but landfill not only occupies a large amount of taxi land, but also has a negative impact on the ecological environment. A large number of garbage has been stored for a long time, resulting in leachate pollution to the surrounding environment. The dioxin content produced by direct incineration of garbage seriously exceeds China’s environmental protection standards and harms human health. The phenomenon of domestic refuse siege is becoming more and more serious. At present, there is an urgent need for disposal methods suitable for the characteristics and conditions of domestic refuse in China, so as to make the waste harmless, resource-based and reduced, and fundamentally solve the secondary pollution problem of waste disposal.
For a long time, because the large-tonnage (large-scale waste incineration plants over 500 tons/day) waste incineration power generation is the professional field of state-owned enterprises and central enterprises, Luoyang Building Materials Architectural Design and Research Institute has focused on the small and medium-tonnage (less than 350 tons/day) domestic waste treatment market, and spent more than ten years independently developing domestic waste pyrolysis and gasification technology, which has broken the big domestic enterprises. Tonnage domestic waste disposal is an industry problem with large investment and serious secondary pollution. Below we will understand the process and technology of domestic waste pyrolysis and gasification.

II. Overview of Domestic Waste Pyrolysis and Gasification Power Generation Technology

Pyrolysis and gasification technology is called the third generation waste treatment technology, and it is the latest method of waste treatment. Pyrolysis gasification power generation technology adopts unique proprietary technology in furnace body design. “After the garbage is transported to the power plant, it is piled up for 3 to 5 days for further fermentation. After that, the garbage will be sent to the first combustion chamber of the furnace, where it is dried, pyrolyzed and gasified to combustible gases. The temperature of the first combustion chamber is 600-800 degrees Celsius. After that, the combustible gases enter the second combustion chamber and are fully burned here. Organic matter is heated in anaerobic and anoxic conditions to decompose into flammable gases. In the process of pyrolysis and gasification, electricity can also be generated, with an average of 320 kilowatt-hours generated by a ton of garbage, and the residue generated thereafter can be used in the building materials industry. The gases, solids and water produced in the whole process can be treated and recovered, and the discharge after garbage treatment is greatly reduced. “This technology effectively avoids the long-distance transportation of garbage and realizes on-site treatment, which is very suitable for small and medium-sized cities.

III. Pyrolysis and Gasification Process of Domestic Waste

Waste pyrolysis gasification (resource) treatment system mainly includes: receiving and feeding system, pyrolysis gasifier system, waste heat utilization (power generation) system, flue gas purification treatment system, ash collection system, landfill leachate treatment system, automatic control system, etc.

III.Characteristics of rotating pyrolysis and gasification technology for domestic waste

Unlike traditional direct Chu-firing methods (such as grate, rotary kiln, solidified bed, etc.), the basic principle of solid waste pyrolysis and gasification process is to completely treat solid waste and fully recover energy under the condition of no oxygen or lack of oxygen. The fuel-to-flue gas cycle process at high temperature includes the following steps: drying, pyrolysis, gasification and combustion. The first three processes are carried out in the first combustion chamber, while gas combustion occurs in the second combustion chamber. Thermal decomposition is carried out under anaerobic or anoxic reduction conditions. The first combustion chamber is full of quiet combustible gases and always maintains a negative pressure environment in order to prevent the waste from burning directly in the furnace, ensure the inert state of the interior and enable the waste to be fully pyrolyzed. Therefore, compared with the traditional direct incineration of waste, the production of NO, HCL and other harmful substances is greatly reduced, thus the amount of waste gas is also less. The pyrolysis and gasification process of refuse developed by Luoyang Building Materials Architectural Design Institute is to pyrolysis and gasify refuse under high temperature and anoxic conditions, and produce flammable gases with CO, H2 and CH4 as the main components, which can be directly used for internal combustion engine power generation. The waste heat generated by the system can be recovered by circulating cooling system and waste heat boiler, so as to realize the cascade utilization of energy. The efficiency of the system can be increased by 95%. At the same time, the waste generated by the system can be reused as building materials. Compared with the traditional fixed gasifier, the rotary pyrolysis vaporizer adopts the rotary bed technology. The system can run continuously, control the material quantity, residence time and gasification degree in the furnace with high precision and stability, and achieve the characteristics of full utilization of waste and high power generation. At the same time, Luoyang Building Material Architectural Design and Research currently adopts the only international technology of gas purification and coke removal. Gas meets the international emission standards and the use requirements of gas power generation system, and achieves zero discharge of coke-containing wastewater.

Modular Composite Structure

Another characteristic of domestic refuse pyrolysis gasification system is modular combination structure. The unit equipment is simple, and the unit and quantity can be selected according to the treatment scale, so that the overall construction cost is low. It is more flexible and adaptable than other traditional direct incineration systems for configurations with medium capacity (e.g. less than 300 tons per day). The scale of pyrolysis gasifier is variable, it can be monomer, double or multi-body. At present, more pyrolysis gasification devices are used. The processing capacity of single standard module is 25 tons per day. According to the required processing capacity, one or more modules can be combined to achieve the best treatment and economic results. In actual operation, according to the change of garbage disposal capacity or the need of maintenance, the number of unit operation modules can be adjusted on demand, which can save operation costs.
Luoyang Building Material Architectural Design and Research Institute has reached 60 tons per day in one month according to market demand. The gasification unit is placed in a standard container of 40 GP in size, which is mobile, distributed, flexible in layout, suitable for local conditions and waste source treatment.

In addition, pyrolysis and gasification technology can be adapted to the treatment of a variety of solid wastes, that is, not only domestic waste, but also industrial and medical garbage, especially hazardous solid wastes which are not suitable for direct incineration, or which are difficult to deal with directly, including medical garbage. Especially for medical garbage and other hazardous wastes requiring treatment under fully sealed conditions, the traditional direct combustion treatment method under aerobic conditions is difficult to achieve this point. It may not only cause secondary pollution, endanger the health of specific operators, but also increase the treatment difficulty of harmful substances or gases, as well as the treatment cost. This new type of garbage management and treatment The concept of disposal (that is, all kinds of garbage can be packaged and packaged first, then pyrolysis and gasification can be carried out under a completely sealed condition) can meet the requirements of hazardous waste disposal. Even a large number of straws (wheat, maize, etc.) in rural areas can be treated by this technology.

In conclusion, we believe that the technology of waste pyrolysis and gasification is particularly suitable for the treatment of medium and small-scale solid wastes in some districts, counties and development zones of medium and small cities and big cities.

Biomass gasification power generation can use biomass materials such as agricultural and forestry waste, aquatic plants, oil plants, urban and industrial organic waste, and animal waste. The sources of raw materials are wide, the power generation equipment is diverse, and the scale of power generation varies, which has led to the diversification of gasification technology.

First、According to power generation scale

From the scale of power generation, biomass gasification power generation systems can be divided into small, medium and large.

1. The biomass required for small biomass gasification power generation system is small, simple and flexible, and more fixed bed gasification equipment is used. It is mainly used for rural lighting or as a self-supplied generator set for small and medium-sized enterprises. The power generation is generally less than 200KW. The fixed bed gasification equipment can be further divided into three types: upper suction type, lower suction type and happy layer type. The lower suction type is beneficial to reduce the tar content generated by pyrolysis in the furnace, and thus is widely used. The small biomass gasification power generation project designed and developed by Luoyang Building Material and Architectural Design and Research Institute uses rotary gasification equipment. The power of the conventional generator set is 200KW.

2.The medium-sized biomass gasification power generation system is mainly used as a self-supplied power station or a small-scale power station for large and medium-sized enterprises. It is the main mode of current biomass gasification power generation technology. The amount of biomass raw materials required is large and can be adapted to one type or a variety of different biomass materials, gasification mode is mainly fluidized bed gasification, the power is generally 500-3000KW. Fluidized bed gasification technology includes three types of bubbling bed gasification, circulating fluidized bed gasification and dual fluidized bed gasification. Among them, the most research and application is circulating fluidized bed gasification technology, which adapts to biomass raw materials. Strong in nature, it can also be mixed with traditional fuels such as coal and heavy oil. It has high production intensity and high gasification efficiency. The medium-sized biomass gasification power generation project designed and developed by Luoyang Building Material and Architectural Design and Research Institute uses rotary gasification equipment. The power of conventional generator sets is 500KW, 800KW and 1000KW.

3.Large-scale biomass gasification power generation system is mainly used as a power station. It adapts to a wide range of biomass and requires a large amount of biomass. It must be equipped with a dedicated biomass supply center and a pretreatment center. The system power is generally above 5000KW. Although it is still very small compared to conventional energy sources, it will be one of the main ways to replace conventional energy sources in the future as technology matures. In general, the larger the scale of power generation, the lower the cost required for unit power generation, and the more favorable it is to improve thermal efficiency and reduce secondary pollution.

Second、According to power generation equipment

Using different power generation equipment, biomass gasification power generation technology can be divided into the following three categories:

1.The gasification gas is directly burned as a fuel for a steam boiler, and the production of steam drives the steam turbine to generate electricity. In this way, when the gas composition and the heating value change, the stable combustion state can be maintained, the emissions are less polluted and the gas requirements are not strict, and the impurities and ash can be removed by the cyclone separator, and the cooling can be performed.

2.The gasification gas is burned in the gas turbine to drive the generator to generate electricity. The gas turbine must be modified accordingly to pressurize the gasification gas with a lower calorific value to between 9.8X104 and -29.4X105Pa, otherwise the power generation efficiency is lower. In addition, gas turbines have high requirements for gasification gas quality and must have a high level of automation control, so there are fewer biomass gasification power generation systems using gas turbines alone. The medium-sized biomass gasification equipment designed and developed by Luoyang Building Material and Architectural Design and Research Institute is equipped with gas turbine internal combustion to drive generators to generate electricity.

3.The gasification of the gas in the internal combustion engine drives the generator to generate electricity. The simple internal combustion engine group can be used with low calorific value gasification gas alone, gasification gas and oil, compact equipment and simple system, so it is widely used and has high efficiency. However, this method requires strict gas, and the gasification gas must be purified and cooled. The small biomass gasification equipment designed and developed by Luoyang Building Material and Architectural Design and Research Institute is equipped with gas turbine internal combustion to drive generators to generate electricity.

Some power plants use two kinds of power generation equipment to increase the steam boiler combined cycle on the basis of gas turbine power generation, make full use of waste heat and increase production intensity, which is called biomass integrated gasification combined cycle power generation system. The total efficiency of the system can reach more than 40%. It is a large-scale gasification power generation technology that is mainly researched in developed countries and has broad development prospects.

The biomass gasification power generation project designed and developed by Luoyang Building Material and Architectural Design and Research Institute is the core technology of rotary gasification equipment. Through the rotary gasification equipment, the combustible gas obtained by gasification is used for power generation and comprehensive energy supply, and the conventional generator set power is 200KW, 500KW, 800KW, 1000KW. The working principle of biomass gasification power generation project is to convert biomass and domestic garbage into high-temperature gas through gasification system. After heat exchange and purification, high-temperature gas drives the power generation equipment such as internal combustion engine and generator to produce electricity. The heat of the gas after heat exchange and the exhaust gas after combustion of the gas are passed through waste heat boiler, lithium bromide heat and cold unit and other equipment, to achieve cooling and heat supply, and finally achieve the purpose of cooling, heat and electricity. Through the use of energy cascades, energy efficiency is greatly improved, and energy use rate is >95%. Based on the products of cold, hot and electric triple supply (CCHP system), the project will increase the supply of two kinds of saleable commodities – gas and fertilizer, and develop electricity, gas, fertilizer, cold and heat supply (CCHP-5 ) System.

At present, there are three types of small-scale domestic refuse organic combustible waste treatment furnaces, including mechanical grate, rotary kiln retorting and pyrolysis gasifier.
1 .mechanical grate incinerator
The mechanical grate incinerator uses layered combustion technology, which has the advantages of low requirement for garbage pretreatment, wide adaptability to garbage calorific value and simple operation and maintenance. It is the most commonly used municipal solid waste incinerator in the world with the largest disposal capacity from small to large.
It has been widely used in advanced countries such as Europe and the United States. Its single unit can reach 1200 t/d with mature and reliable technology. Garbage usually passes through three sections on the grate: preheating and drying section, combustion section and burning-out section to realize the ignition of garbage on the grate. The heat comes from the radiation above and the convection of flue gas as well as the interior of the garbage layer. The burning garbage on the grate makes the garbage layer turn and agitate intensely through the reversal of the grate, which causes the burning of the bottom of the garbage. Continuous turning and agitation also loosen the garbage layer and enhance the permeability, which is conducive to the burning and burning of garbage.

2. Rotary kiln retorting equipment
The reaction mechanism of rotary kiln retorting equipment is similar to that of scrap tire pyrolysis refining equipment. It consists mainly of an inclined steel cylinder surrounded by a combustion chamber for external heating. The garbage enters the cylinder from the entrance, and moves forward along the rotating edge of the cylinder. The drying and cracking processes of garbage are completed in the cylinder. The residence time of garbage in the kiln can be adjusted according to the change of rotational speed of the cylinder. Rotary kilns are often used in pyrolysis refining of waste tyres and industrial plastic waste. They are also used in domestic waste treatment.

3. pyrolysis gasifier
After drying, the domestic refuse enters the pyrolysis gasifier through conveying equipment. First, it enters the drying section and removes water (including molecular water) at 150 ℃. Drying refuse enters the pyrolysis layer. At 200℃ to 650 ℃, different substances are pyrolyzed to produce flammable gases such as alkanes, hydrocarbons, olefins, etc. At 800 ℃, the substances enter the oxidation section and produce some carbides. Combustion produces a temperature of about 1000 C, which causes the reaction of CO2 and C to produce CO gas. This stage is the gasification stage. After the water vapor enters the fire layer, one is to adjust the furnace temperature, the other is to produce H2 and CO gas, which completes the whole process of pyrolysis and gasification.

Pyrolysis gasification is a controllable combustion and reduction process. The whole process environment is in a state of hypoxia, which can fully restrain the production of dioxins, polycyclic hydrocarbons (PAtt) and aldehydes. Moreover, sulfur and oxygen in garbage are mostly slagging in the form of compounds, and a small part of them form SO2 and HCl.

The function of combustible gas after purification:

(1) It can be used as fuel for burning bricks in tunnel kiln of sintered brick factory. The brick slabs were dried by high temperature flue gas and then used as heat medium for garbage drying drum to dry garbage.

(2) It can be used as fuel for steam or hot water boilers. Steam or hot water can be supplied to the users of steam and hot water to realize profit. The high temperature tail gas of the boiler can be used as heat medium for garbage drying drum to dry garbage.

(3) It can also be used as fuel for internal combustion engines to drive generators to generate electricity, to supply power to the grid or for self-use, and to achieve benefits. The high temperature exhaust gas produced by internal combustion engine can also be used as heat medium for garbage drying drum to dry garbage.

The application of the most advanced third generation garbage treatment technology in the world in the garbage pyrolysis gasifier of Luoyang Building Materials Architectural Design Research Institute can make the garbage completely harmless and fully utilized as a resource. It has the following advantages: low investment, low operation cost, flexible equipment grouping and short construction period. Its process can effectively and timely reduce, harmless and resource-based treatment and utilization of all domestic waste generated on that day. And completely eliminate secondary pollution, save a lot of land resources. The overall process and equipment have reached the international advanced and domestic leading level.