Significance of Cement Rotary Kiln Cooperative Disposal of Hazardous Waste for Future Industrial Development

In recent years, the cooperative disposal of hazardous waste projects in cement kilns has shown explosive growth, and the market prospects are very broad, but the industrial development is still in its infancy.

At present, there are five main problems in the cooperative disposal of hazardous waste in cement kilns in China: project direction, project design, industrial know-how, policy and operation: (1) project direction problem Some enterprises operate cooperative disposal of hazardous waste in cement kilns only for the purpose of cementing non-stop production, and the quality of disposal is difficult to guarantee; (2) project design problem is not detailed enough for the investigation of hazardous waste market to cement production. The scale of application for business license is too large; (3) the technology of cement production process control needs to be improved in the process of synergistic disposal of industrial proprietary technical problems, and the equipment of waste conveying into kiln and pretreatment needs to be upgraded; (4) in the mode of “pretreatment + cement kiln” operation, the product quality standard of pretreatment Center is not clear, resulting in It is difficult to implement it in practice; (5) The operation problem is extensive management of hazardous waste disposal process line with the thinking of cement production, and it is difficult to balance the output of cement production and the quantity of hazardous waste disposal.

Cooperative disposal of hazardous waste in cement kiln is a waste disposal method which can decompose, degrade, eliminate, inert and stabilize the toxic characteristics of hazardous waste through high temperature incineration and sintering of cement clinker minerals, and reuse the useful components at the same time. The ability of synergistic disposal of hazardous wastes is related to the process condition of cement kiln, raw material condition and waste characteristics. High disposal temperature, strong stability, long residence time, large incineration space, large scale of treatment, environmental protection and safety, no residue is an important technical advantage of collaborative treatment of hazardous wastes.

Collaborative disposal of many wastes in cement kilns is prohibited, including radioactive wastes, contagious, explosive and reactive wastes, undisassembled waste batteries, waste household appliances and electronic products, mercury-containing thermometers, sphygmomanometers, fluorescent lamps and switches, chromium slag produced during the production of chromium salts by calcium roasting process, asbestos wastes, unknown characteristics and unidentified ones. Solid waste, etc.

The key points of the process for the co-disposal of hazardous wastes in cement kiln are as follows: (1) the burnable materials should be avoided from contacting directly with the materials in the anaerobic state; (2) the oxygen content in the decomposition furnace is related to the discharge; (3) the process accidents can be reduced by setting the decomposition furnace temperature reasonably; (4) the pulverized coal should be fully burned, otherwise the cement performance will be affected.

Through the control of detection, calculation and adding speed, the content of “unnecessary” elements in clinker can be guaranteed to be within the capacity. Because of the physicochemical characteristics of hazardous waste, the waste with high volatility, flammability, explosiveness and strong cohesion should be guaranteed to enter the kiln safely. It is necessary to ensure that no secondary pollution occurs during storage, transshipment and tail gas discharge.

There are several points about the future development of the cooperative disposal of hazardous waste in cement kiln: (1) The cooperative disposal of hazardous waste in cement kiln is a direction of industrial development, and will eventually change from harmless to resource-based. With the improvement of disposal capacity, the market price of hazardous waste disposal will fall back; (2) With the development of industry and the improvement of policy, the cooperative disposal of hazardous waste in cement kiln will return to the essence of hazardous waste disposal, and will no longer be the talisman of “staggered peak production”; (3) the regional government should formulate a plan for the cooperative disposal of hazardous waste in cement kiln to avoid regional surplus; (4) the cooperative disposal of hazardous waste suitable for China’s national conditions of high water. Lack of complete sets of pretreatment and disposal equipment with high automation and quality will bring opportunities for development in the field of equipment; (5) Standards for disposal of hazardous waste in cement kilns will continue to be improved, and existing policies will be refined and landed.

Luoyang Building Material Architectural Design and Research Institute is committed to the innovation and development of technology and equipment in building materials and construction industry. It has Grade A design and Research Institute which integrates scientific research and development, design, general contracting, supervision, technical consultation and technical service of building materials and construction engineering. At present, more than 60 new dry-process cement clinker production lines of various scales (300-8000 tons per day), more than 10 low-temperature waste heat power generation projects supporting cement clinker production lines, more than 20 cement grinding station projects and dozens of other industrial and civil construction projects have been completed.

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What are the sludge treatment steps?

First, the raw sludge is pumped from the secondary settling tank to the other tank through the sludge pump to be separated from the supernatant. Since the moisture content of the raw sludge can usually reach 99.5%, the sludge must be concentrated and there are many feasible methods for reducing the volume of the sludge. Methods of mechanical treatment such as vacuum filtration and centrifugation are typically used before the sludge is disposed of in a semi-solid form. Usually these methods are preparations for sludge incineration. If biological treatment is planned, most will be concentrated by gravity sedimentation or air flotation. The sludge corresponding to these two conditions is still in a fluid state.

The gravity concentrate tank is designed and operated similar to the secondary settling tank in wastewater treatment. The concentrating function is the main design parameter. In order to meet the greater concentration capacity, the concentrating tank is basically deeper than the secondary settling tank. A properly designed, well-functioning gravity concentrating tank can at least double the sludge content. That is to say, the moisture content of the sludge can be reduced from 99.5% to 98%, or less. It is worth mentioning here that the design of the gravity concentration tank should be based on the analysis of the Chinese results as much as possible, because the appropriate sludge loading rate has a lot to do with the properties of the sludge.

If dissolved air flotation is used, a small portion of water is required, usually the secondary settling tank, which is inflated at a pressure of 400 kPa. This supersaturated liquid passes to the bottom of the tank and the sludge passes under atmospheric pressure. The gas adheres to the solid particles in the sludge in the form of small bubbles, or is surrounded, thereby causing the solid particles to float to the surface. The upper portion of the concentrated sludge is removed, and the liquid flows back from the bottom to the dissolved gas tank.

After the volume is reduced, the sludge contains a large amount of harmful components, which need to be converted into inert components before disposal. The most common method is stable biodegradation. Because this process aims to convert the material into a final sterile product, the method of digestion is often applied. Sludge digestion can further reduce the volume of sludge and also convert the solids contained into inert materials and generally no pathogens. Sludge digestion can be achieved by anaerobic digestion or good digestion.

Sludge contains a variety of organic matter and therefore requires a variety of microorganisms to decompose. The relevant data divides the microorganisms in anaerobic digestion into two categories: acid-producing bacteria and methanogens. Therefore, we can also divide anaerobic digestion into two steps.

In the first step, an acid-producing bacterium consisting of facultative anaerobic bacteria and anaerobic bacteria dissolves the organic solid by hydrolysis. The solute is then converted to alcohol and low molecular weight molecules by fermentation.

In the second step, methanogens consisting of strict anaerobic bacteria convert acetic acid, alcohol, water and carbon dioxide into methane. Because the two flora can only survive in an anaerobic environment, the anaerobic digestion reactor must be sealed. There are other factors to consider when designing the container, such as temperature, pH, and mixture agitation.

Sludge can also be stabilized by aerobic digestion. This digestion can basically only be used for biochemical sludge and not for primary sedimentation tanks. With the reduction of sludge volume in the secondary sedimentation tank and sludge concentration tank, this process requires constant aeration. Aerobic digestion is mostly used in deep aeration systems. Furthermore, aerobic digestion is not sensitive to environmental conditions and is not limited to epidemic changes.

After the sludge is digested, the organic matter in the sludge can be removed and the sludge volume can be further reduced. Next, the sludge needs to be disposed of. A variety of methods can be used to effectively dispose of the sludge. These include incineration, sanitary landfills and use as fertilizers and soil amendments. The raw sludge can be used for incineration, which can effectively reduce the water content. Adding fuel can be used to cause and sustain combustion, and municipal waste can also be used to achieve this goal.

Raw sludge and digested sludge can also be disposed of in sanitary landfills. The land application of sludge has been practiced for several years and is now limited to the treatment of digested sludge. The nutrient content of the sludge is conducive to plant growth, and its particle characteristics can be used for land improvement. These applications are limited to forage crops and non-human consumption, and the possibility of supporting edible plants is under investigation. The main limiting factors for sludge land application are plant enrichment metal toxicity and water eutrophication. The application of sludge can be carried out by sprays from sprinklers, diversion of ditches or direct injection into the soil. Dewatered sludge can be laid on the land and cultivated by traditional agricultural machinery.

The above text refers to the treatment of general sludge. Because sludge can cause environmental pollution, we need to do our best to make it harmless. Nowadays, many sludges with different characteristics that lead to type pollution are under study. In this article, I will describe a sludge from the human oil and petroleum industry. This representative sludge is called oily sludge.

A large amount of sludge is produced, and this sludge contains a considerable amount of oil and must be removed before final disposal. Sludge from refineries cannot be disposed of safely unless the oil content is removed to a certain extent.

In addition, in the oil-water separation system and the oil storage tank of the refinery, the sludge generated due to the accumulation of the oil-containing raw materials is expensive to handle, and causes serious pollution to the environment. Petroleum is a hydrophobic mixture such as alkanes, aromatic hydrocarbons, resins and asphalt. Many compounds are toxic, mutagenic and carcinogenic. Their emissions are tightly controlled because of their negative impact on human health and the environment, and they are classified by the US Environmental Protection Agency as a priority for environmental pollutants.

There are many ways to treat oily sludge. Chemical and physical methods such as incineration, chlorine oxidation, ozone oxidation and combustion, biological treatment methods such as bioremediation, traditional composting, and the like. Nowadays, with the development of technology, low temperature cold treatment and bioremediation of oily sludge have become two effective treatment methods.

As a physical treatment method, low temperature cold treatment technology can effectively increase the dewatering properties of sludge, change the structure of flocculant and reduce the water content around the sludge. Comparing the “initial settling”, the cold treatment removes impurities from the solution and thus achieves better concentration. This is the benefit of cold treatment. To the best of our knowledge, there is no discussion of the feasibility of cold treatment techniques to separate oil from sludge in today’s data. However, in many countries where natural conditions permit, cold treatment technology provides an effective means of handling the treatment and disposal of oily sludge.

By comparing the conventional method with the sludge after the cold treatment, we can find that a layer of oil floated on the sample after the cold treatment. Finally, we can find that the test tube is divided into three layers: the uppermost layer is a clear oil slick, the bottom layer is a layer of dark sediment, and the middle layer is clear water. After the original sludge settled for 24 hours, the supernatant and bottom sediment were visible, but there was no visible oil phase. The phenomenon described above reveals that a simple cold treatment can effectively separate the oil in the sludge.

The physicochemical method can be used to treat sludge, but the cost is very high. Composting and bioremediation by degrading oil strains or activating existing organisms by inoculation is seen as two economical methods to deal with oil pollution. Some of the compelling advantages of composting are: low capital and maintenance costs, simple design and operation, and the ability to remove some of the oil. However, composting is basically unable to meet the standards of today’s environment.

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Optimum Design of Manufactured Sandstone Aggregate Production Line

With the upgrading and adjustment of the national industrial structure, the production of machine-made aggregate has entered the industrial era, and the corresponding design, production and quality control standards have gradually improved. As an industrial product, machine-made aggregate not only promotes the change of market consumption concept, but also promotes the development of diversification of concrete performance. However, due to the diversity of raw materials and market demand, the technical level of engineering design units and other reasons, the sand production line can not achieve the desired results after putting into operation.

The environmental pollution of machine-made aggregate production line is mainly dust, noise and sewage produced in the production process. The treated wastewater and noise can meet the national standard. This paper mainly introduces the dust control measures from three points: dust reduction, dust reduction and dust collection.
The optimum design of machine-made sand aggregate production line includes the following aspects:

1. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

By optimizing the design, the dust in the production process can be reduced.

1) Controlling the cutting angle of the silo and making cushioning design at the lower part of the silo can not only reduce the impact of material flow on the feeder, but also reduce the dust raised during feeding.
2) Equipment sealing design, flange connection between chutes, ladder chute for unloading, etc.
3) To minimize the material transfer point and drop.

2. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

Mainly through efficient spray device to reduce the suspended dust as soon as possible, reduce pollution:
1) the top of the material unloading bin is equipped with a spray device to remove dust when discharging.
2) a spray device is installed above the blanking point of intermediate storage yard and finished product yard to realize dust suppression.

3. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

1) Designing the dust collection system by reasonable arrangement and balanced calculation. For aggregate line, the angle of dust collecting duct is generally controlled at not less than 55 degrees in the upwind duct and 40 degrees in the downstream duct; the wind speed of dust-containing duct is controlled at about 15 m/s and the wind speed of clean duct is controlled at about 12 m/s; the number of dust collecting points of the same collector is as small as possible, not more than 8; the number of elbows of dust collecting duct should be minimized; the design should achieve the balance of air volume and pressure of dust collecting system. 2.
2) Dust collection system has balanced calculation, reasonable layout, avoid waste caused by random selection. For example, the sand and gravel production line system of an enterprise: the dust lifting points of the production line such as crushing and screening are all one-to-one dust collection, the air handling capacity of the selected dust collector is about 40,000 m3/h (actually not needed), and the configuration of dust collector and fan is large, resulting in waste of investment and increased operation cost. Therefore, the balance calculation and reasonable arrangement of dust collection system should be paid attention to in design.

As an important index of Engineering construction, project investment has been attached great importance by more and more enterprises. It is found that the investment of the machine-made sand aggregate production line varies greatly. The total investment of a 1500 TPH sand aggregate production line is about 250 million yuan, that of a 2-1000 TPH sand aggregate production line is about 130 million yuan, and that of an 800 TPH sand aggregate production line is about 35 million yuan. Although there are many differences in raw materials, equipment, technology and so on, there is no absolute comparability in investment. But similar conditions, the same size of the project, or comparable. Using the experience of scale investment in cement industry for reference, the sand and stone industry can optimize engineering design and control construction investment to prevent waste of investment due to inadequate pre-project work, unreasonable site selection and production line allocation.

In recent years, Luoyang Building Material Architectural Design and Research Institute has designed and completed nearly 80 production lines of machine-made sand aggregate of various scales, and accumulated a lot of engineering design experience. The designed sand and gravel production lines of various scales have the following characteristics: reasonable matching of crushing equipment, compact space layout, small area, high investment and economic benefits, good quality of gravel and low output rate of stone powder. At the same time, the production line adopts the computer DCS control operating system to achieve accurate production control, automatic operation, ensure product quality and reduce labor intensity.

The production line designed by Luoyang Building Materials Architectural Design Research Institute has the following characteristics:
1. The production line is flexible: suitable for large-scale production with capacity of 500-3000 tons/hour;
2. The production cost of finished sandstone is only 3/5 of that of conventional production line.
3. Production automation is high, energy consumption is low and crushing ratio is high.
4. The payback period is short and the investment can be recovered in 4-5 months.
5. It has plastic function and the product is cuboid.
6. The finished product has good granularity and meets the national standard. Quartz sand production technology in sand and gravel production line (stone production line).

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Planning of gravel aggregate yard

I. Overview of Sandstone Aggregate

Sandstone aggregate is the most basic component of concrete. Usually, 1.3-1.5m_3 loose aggregate is needed for every m_3 concrete. Therefore, for a project with a large amount of concrete, the requirement of sand aggregate is also quite large. The quality of aggregate directly affects the strength of concrete, cement dosage and temperature control requirements, thus affecting the quality and cost of the project. Therefore, in the design and construction of gravel aggregate mines, overall planning should be made, and the components, quality, reserves, physical and mechanical indicators, impurity content, mining, transportation, storage and processing of gravel aggregate should be carefully studied. _

II. Planning of gravel aggregate yard

The planning of gravel aggregate yard is the basis of aggregate production system design. The optimum scheme depends on the distribution and elevation of the material yard, aggregate quality, reserves, natural gradation, mining conditions, processing requirements, the number of discarded materials, transportation mode, transportation distance, production cost and other factors. The planning and optimization of gravel aggregate yard should be carried out through comprehensive technical and economic demonstration. The quality of gravel aggregate is the first prerequisite for material yard selection.
The quality requirements of aggregate include strength, frost resistance, chemical composition, particle shape, gradation and impurity content. The coarse aggregates of cast-in-situ hydraulic concrete are mostly made up of four gradations, namely, 5~20, 20~40, 0~80~120 (or 150) mm. Sand is fine aggregate, which is usually divided into coarse sand and fine sand. Its size gradation is controlled by fineness die. The reasonable value is 2.4~3.2. Increasing aggregate particle size and improving gradation are of positive significance for reducing cement consumption and improving concrete quality, especially for temperature control and crack prevention of mass concrete. However, the natural gradation and design gradation requirements of aggregates are always different, and the reserves of various gradations can not meet the requirements at the same time. This requires more mining or processing to adjust the gradation and its corresponding output. There are three sources of aggregate in construction projects: natural aggregate, artificial aggregate and composite aggregate.

III. Principles of Sandstone Aggregate yard Planning

The following principles should be followed in the planning of sand and gravel yard:
(1) To meet the quality requirements of aggregates for concrete in construction projects, its reserves should satisfy the needs of various design gradations and the necessary affluence;
(2) The selected material yard, especially the main material yard, should be open, elevation appropriate, large reserves, good quality, long mining season, and the main and auxiliary material yard should be able to take into account the requirements of flood and dry seasons for each other;
(3) Choosing a material yard with high recovery rate and close natural gradation to design gradation, and adjusting gradation quantity with artificial aggregate;
(4) There are enough return and stockpiling sites near the stockyard, and less farmland is occupied.
_Choosing a material yard with small preparation workload and simple construction. _

IV. Application of Planning Principles for Sandstone Aggregate Yard

If the above requirements are difficult to meet at the same time, we should meet the main requirements, that is, to meet the quality, quantity and quantity as the basis, to seek a low cost scheme for mining, transportation and processing, and to determine whether to use natural aggregates, artificial aggregates or composite aggregates. If aggregates are combined, the optimum mixing scheme of natural aggregates and artificial aggregates should be determined. Usually for the oversize material in the natural material yard, the shortage gradation is supplemented by processing to form a closed-circuit cycle of the production system, which is a good way to reduce waste and cost. If the natural aggregate scheme is adopted, in order to reduce the discarded materials, the gradation of each material yard should be considered to meet the best combination of the material yard. Obviously, natural material yards with good quality, large quantity and short transportation distance should be preferred. Artificial aggregate is considered only when natural materials are transported too far away and the cost is too high. _

V. Characteristics of Artificial Aggregate

The gradation of artificial aggregate can be easily adjusted to meet the design requirements through mechanical processing. Artificial crushed gravel with rough surface and high cementing strength with cement mortar can improve the tensile strength of concrete and prevent concrete cracking. With the development of large, efficient and durable aggregate processing machinery and the improvement of management level, the cost of artificial aggregate is close to or even lower than that of natural aggregate. Artificial aggregate has many advantages that natural aggregate production does not have, such as adjustable gradation, stable quality, relatively centralized management, less affected by natural factors, which is conducive to balanced production, reduce equipment consumption, reduce stacking site, and the use of effective excavation materials. Therefore, more and more projects using artificial aggregates, such as Yingxiu Bay in Sichuan, Wujiangdu in Guizhou, Dongfeng in Yunnan, Manwan in Yunnan, Dahua in Guangxi, Yantan and other projects using artificial aggregates or mechanical processing aggregates, have achieved obvious technical and economic results in practice.

Luoyang Building Material Architectural Design and Research Institute is a professional research institution of building materials and construction grade A. It has more than 20 years’experience in mineral materials research and design and construction of nearly 100 sand and stone aggregate lines. Our institute can provide a complete set of technical services of sand and stone aggregate production line according to customers’ needs: feasibility study report, design, general package, production improvement, intelligent transformation, etc. Providing customers with the latest technology, taking full account of cost savings, investment efficiency, meeting the most stringent environmental requirements, and relieving customers’worries.

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Treatment of heavy metals in municipal sludge

With the improvement of the living standards of our residents and the development of urban economy, the construction of urban sewage treatment equipment in China has been continuously strengthened, and a large amount of sludge will be produced in the sewage treatment process. The composition of the sludge is extremely complex, and it is bulky, fragile, unstable, and stinky. If these sludges are not treated in a timely and effective manner, they will bring serious pollution problems to the environment. In particular, the treatment of heavy metals in municipal sludge has become a major problem in sludge reuse.

First, how to deal with urban sludge?
At present, there are three main treatment methods for municipal sludge:
1. Incineration sludge treatment
Incineration sludge treatment is to incinerate sludge on a professional production line, which will pollute the atmosphere and consume a lot of energy;
2. Landfill sludge treatment
Landfill treatment sludge is to directly fill the dewatered sludge at a designated location, but the leakage of harmful components inside it will pollute the groundwater, and the waste gas generated by landfill will cause air pollution;
3. Sludge agricultural compost
Sludge agricultural composting is because there are a large number of biological compounds and organic matter that can be used as fertilizers in urban sludge, which can improve soil fertility, but heavy metal pollution is difficult to remove, which is the main obstacle for sludge agricultural composting.

Continue to use the existing method to treat sludge, which not only occupies a large amount of land, but also causes soil and groundwater pollution. Therefore, how to find a more effective sludge treatment method and achieve the goal of stabilization, resource utilization and harmlessness It has become a very urgent task.

The use of dehydrated municipal sludge to solidify heavy metals to prepare high-strength ceramsite provides a good solution for the safe application of sludge treatment end products. It not only solves the problem of stacking a large number of dewatered sludge, but also avoids the secondary damage caused by improper discharge. Pollution. Moreover, ceramsite as a lightweight aggregate can not only be used in basic buildings, but also alleviate the crisis of building materials such as sand and stone. It provides a new channel for the building materials industry to dispose of municipal sludge, and also responds to the current trend of resource utilization in the country. , the country and the people.

Sludge particles

Second, the process of preparing high-strength ceramsite by solidifying heavy metals from municipal sludge
1. Ingredients: Mix dehydrated municipal sludge, saline soil, plasticizer and water in a certain proportion and stir evenly;
2. Granulation: the mixture is placed in a granulator to be granulated, and the particles are spherical or elliptical;
3. Drying: the granulated granules are placed in a drying device for drying;
4. Calcination: The dried granules are sintered in a high-temperature calcining apparatus to obtain ceramsite.

Third, the advantages of using municipal sludge to solidify heavy metals to prepare high-strength ceramsite

1. Municipal sludge solidified heavy metal The main raw material for the preparation of high-strength ceramsite dehydrated municipal sludge and saline soil are solid waste, which not only solves the problem of stacking existing large amounts of sludge, but also avoids the environmental pollution caused by improper discharge. Secondary pollution, and the realization of the harmless and resource-based treatment of solid waste, reducing waste of resources, and achieving safe disposal of municipal sludge. At the same time, it is economically and feasible to use urban sludge to prepare high-strength ceramsite products. The obtained ceramsite can solidify the heavy metals contained in the raw materials, which is beneficial to resource recycling and environmental protection, and also reduces the ceramsite industry. The demand for natural raw materials;

2. The ceramsite prepared by this method not only has good structural strength, low water absorption, high hardness and good chemical stability, but also has an enamel layer or glass body covering on the surface of the ceramsite, which greatly enhances the curing ability of heavy metals in the sludge. Because the urban sludge high-strength ceramsite has the advantages of light weight, high strength, durability and good solid metal curing effect, it can be used for lightweight building components or thermal insulation materials, and the characteristics of urban sludge high-strength ceramsite are in line with modern architecture. The need of the industry, the material instead of sand and gravel as the aggregate in lightweight concrete, greatly ease the pressure of natural aggregates;

3. According to the rotary ceramsite carbonization preparation method developed by Luoyang Building Material and  Architectural Design and Research Institute, the mechanical strength and heavy metal pollution index meet the requirements of national construction high-strength light aggregate, and the heavy metal content far meets the hazardous waste identification standards and Hazardous waste landfill standards have also developed positive and feasible channels for the resource utilization of municipal sludge.

In December 2018, Luoyang Building Material and Architectural Design and Research Institute independently developed and designed, providing core equipment for sludge hydrolysis and carbonization resource utilization comprehensive utilization project, which was put into operation in Huzhou City, Taihu Lake, with an annual processing capacity of 66,000 tons of water-containing sludge. The sludge ceramsite is 29,800 tons. The project is a demonstration project for the “13th Five-Year” National Sewage Special Treatment Sludge Resource Utilization, which has received extensive attention from governments at all levels and provided advanced solutions for environmental management in the Taihu Basin.

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Brief introduction of sludge pyrolysis retorting gasification process

First, What is sludge pyrolysis retorting gasification?

Sludge pyrolysis retorting gasification is to use a composite heating mode to heat the sludge to 150 ° C ~ 600 ° C, the organic matter and water are separated from the solid phase and converted into gas phase; then enter the filter device to filter out the dust in the hydrocarbon vapor. The clean hydrocarbon vapor is introduced into the condensing and separating system, and the water, oil and dry gas are separated in different temperature ranges, and respectively enter the gas cabinet, the oil tank and the water tank. The exhausted tail passes through the dust collecting and purifying system to purify the exhaust gas. , to meet emission standards.

Oil sludge treatment process flow

Second, The six core systems of sludge pyrolysis retorting gasification

The six core systems for sludge pyrolysis retorting gasification include: pretreatment system, pyrolysis retorting gasification system, condensing separation system, flue gas purification system, waste heat utilization system and automatic control system.

1. Pretreatment system
The pretreatment system is: pretreatment for crushing the sludge;
2. Pyrolysis retorting gasification system
The pyrolysis retorting gasification system is: after heating the sludge to 150°C to 600°C in a composite heating mode, the organic matter and water are converted into a gas phase, separated from the solid phase, and then enters a filtering device to filter the dust in the hydrocarbon vapor. To allow clean hydrocarbon vapors to enter the condensing separation system;
3. Condensation separation system
The condensing separation system is: hydrocarbon vapor enters the condensing system, and separates water, oil and dry gas in different temperature ranges, and enters the gas cabinet, the oil tank and the water tank respectively;
4. Flue gas purification system
The flue gas purification system is: purifying the exhaust gas after the combustion through the dust collecting and purifying system to meet the discharge standard;
5. Waste heat utilization
The waste heat utilization is: the high-temperature exhaust gas discharged from the system converts the heat energy through the waste heat boiler and the heat exchanger, and can provide the purposes of power generation, heat supply and cooling;
6. Automatic control system
The automatic control system is: using advanced computer distributed control system (DCS system) to realize automatic control and remote monitoring of all parameters of the system.

Third, The core technology of sludge pyrolysis retorting gasification

Core technology of sludge pyrolysis retorting gasification

Fourth, The innovation of sludge pyrolysis retorting gasification
1. Modular design: easy to transport and quick installation, can be configured according to project needs;
2. Wide range of applications: it can handle all kinds of oily wastes, and can also be used for soil remediation and other chemical solid waste hazardous waste treatment;
3. Continuity: The system can operate continuously for 8000 hours/year;
4. The solid content of the system processed is less than 0.3%, meeting the most demanding environmental requirements;
5. Unique inlet and discharge design to meet the continuous operation of high viscosity materials;
6. Advanced automatic intelligent control system enables the equipment to operate safely and efficiently;
7. High-temperature pyrolysis retorting and indirect heating of materials. Compared with incineration technology, no harmful gas emissions are generated, and the entire system can meet the most demanding emission requirements.

Entrusted by a department in May 2014, Luoyang Building Material and Architectural Design and Research Institute carried out research and development of comprehensive utilization of oil sands in Buton Island, Indonesia. In June 2015, completed the development and construction of a 100,000 tons/year oil sands dry distillation pilot line, and successfully produced Out of the first barrel of high quality shale oil. In July 2016, the annual production line of 400,000 tons of oil sludge sand was started, and it was put into operation in June 2018.

 

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The utilization rate of waste heat recovery in China is low, and the development and utilization of waste heat is promising.

Recovery of waste heat

Recovery of waste heat

Waste heat resource refers to the part of energy that is likely to be recovered and reused but not yet recovered under the current conditions. It is considered to be the fifth largest conventional energy after coal, oil, natural gas and water power. These waste heat resources can be used for power generation, driving machinery, heating or refrigeration, so as to reduce the consumption of primary energy and reduce the thermal pollution of the environment.

China’s huge energy consumption has produced a large number of waste heat resources, but the data show that about 50% of industrial energy consumption has not been utilized, and the average recovery utilization rate of waste heat resources is only about 30%. That is to say, in 2018, the total amount of recycled resources is 236 million tons of standard coal, the highest is 929 million tons of standard coal, with an average of 554 million tons of standard coal.

Generally speaking, the recoverable waste heat resources are about 60% of the total waste heat resources, while the average recovery utilization rate of waste heat resources in developed countries is also 40% – 60%. Assuming that in the future, with the encouragement and support of national policies for waste heat recovery and the continuous improvement of waste heat recovery technology and efficiency, the utilization rate of waste heat recovery in China will reach 60%, and the recoverable waste heat resources will reach 471-1857 million tons of standard coal, with an average of 1.109 billion tons of standard coal, which has great potential for energy saving.

High temperature flue gas waste heat and cooling medium waste heat are the main sources of waste heat utilization, accounting for up to 70%.

The sources of waste heat resources can be divided into six types: high temperature flue gas waste heat, cooling medium waste heat, waste gas waste water waste heat, high temperature products and slag waste heat, chemical reaction waste heat, combustible waste gas waste liquid waste heat and waste material waste heat. Among them, high-temperature flue gas waste heat is large in quantity and widely distributed, such as metallurgy, chemical industry, building materials, machinery, power and other industries in various smelting furnaces, heating furnaces, internal combustion engines, and easy to recover, so high-temperature flue gas waste heat accounts for about 50% of the total waste heat resources.

Secondly, cooling medium waste heat accounts for about 20% of the total waste heat resources, mainly because industrial production needs a large number of cooling medium to protect thermal insulation equipment. However, because the temperature of the cooling medium is generally low, and most of them are water, air and oil, it is very difficult to recover the waste heat of the cooling medium.

In addition, waste water and waste gas waste heat account for about 11% of the total waste heat resources, and the former types of waste heat are less than 10%.

As early as 2010, China surpassed the United States to become the world’s largest energy consumer, with primary energy consumption reaching 3.606 billion tons of standard coal. After 2010, although energy consumption slowed down, it showed an overall growth trend, reaching 4.62billion tons of standard coal in 2018. Huge energy consumption produces a large amount of waste heat resources. According to the total waste heat resources accounting for 17% – 67% of the total fuel consumption, the total waste heat resources in 2018 reached 785 – 3095 million tons of standard coal. However, at present, domestic waste heat recovery and utilization accounts for only about 30% of the total waste heat resources. It is expected that in the future, the domestic waste heat recovery and utilization will reach 60% in the developed countries and the prospects for recovery and utilization are very promising.

Luoyang Building Material Architectural Design Research Institute (LCDRI) is a state-level high-tech enterprise specializing in industrial equipment research and development. It specializes in researching waste heat power generation technology of cement plants, actively responding to the national energy-saving and emission reduction policies, creating energy-saving and environmental-friendly enterprises, and reducing production costs through waste heat recovery and utilization, so as to improve the efficiency of enterprises.

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East Asian Customers Exchange and Negotiate with Our Institute on Cement Production Line Projects

On May 21, Mr. Sadati, a client from East Asia, and his team came to our institute to discuss the construction of a 500-ton cement clinker production line. Accompanied by the relevant personnel of our institute, we inspected the production base and initially reached the intention of cooperation.

Clients come to visit our company

Clients come to visit our company

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The Difference between Traditional Ceramic Granule Preparation and Sludge Ceramic Granule Preparation

In recent years, the ceramisite industry has actively responded to the basic national policy of resources and environmental protection, using construction waste soil, municipal sludge and sludge as the main raw materials to produce ceramisite, which has achieved good economic benefits and greatly relieved the enormous pressure brought by environmental factors. Ceramic is widely used as building materials, green materials, food and health materials, industrial filter materials and so on. A wide range of applications have attracted many people to enter the ceramsite preparation industry. Now, several conventional ceramsite preparation methods are briefly introduced. At the same time, the differences between sludge ceramsite preparation are analyzed.

I. Bauxite Ceramic Sand Technology

1. Crushing: The bauxite that is mined usually crushes the stone about 300-500 mm to the size less than 8 mm.

2. Ingredients: Bauxite, manganese powder, recycling and other materials are respectively transported to their respective warehouses, under which a speed-regulating belt scale is set up to realize automatic burden metering.

3. Grinding: Ball mill with both drying and grinding is generally used, and high-efficiency separator is matched to form closed-circuit system. The hot air for drying materials can come from the waste gas of rotary kiln to make use of the waste heat, and special hot air stoves can also be set up.

4. Ball making: raw meal powder from grinding is stored in raw material storehouse. Then enter the disc ball machine. At the same time, water is sprayed into the disc ball-making machine with a pipe pump. After the ball is discharged, it is qualified to enter the rotary kiln through the screening device.

5. Calcination: The material ball enters the rotary kiln with a certain slope for calcination. As the rotary kiln rotates, the material ball rolls towards the kiln head. At the same time, the coal powder is sprayed from the kiln head into the kiln for combustion. The material ball is calcined into high strength ceramisite sand in the rotary kiln.

6. Screening: The ceramsite sand from the cooling machine can be directly transported to the multi-stage vibrating screen, which can be divided into several particle sizes according to the requirements.

II. Shale Ceramic Sand Technology

The production process of shale ceramsite is generally divided into five stages: raw material preparation, drying, preheating, roasting and cooling. The raw shale ore is crushed by jaw crusher and sifted after crushing. The size of the raw material is 3mm~5mm. The raw material is then fed into the electric furnace for preheating. After preheating, the raw material is immediately fed into the electric shale furnace which is already at the target temperature for roasting. After roasting, the ceramisite is cooled at room temperature.

The drying, preheating, roasting, cooling time and temperature selection of shale raw materials are called ceramsite roasting system. Research on ceramsite roasting system is the main content of ceramsite roasting research. The quality of ceramsite will be affected by various factors in the process of ceramsite preparation.

III. Clay Ceramic Sand Technology

Clay ceramsite has been banned from production and use in some areas due to the limitation of land resources in recent years. But in some areas, River silt and abandoned mountain soil can be used for production. Clay ceramsite is usually made by plastic process, the process is as follows:

Plastic process: suitable for clay and clay raw materials

Flow 1: Clay plasticization, homogenization counter-roll granulation roasting cooling finished products

Flow II: Material agitation – granulation – Screening – sintering – stacking – transportation (bagging)

Flow I and Flow II have the same process. Attention should be paid in operation to prevent material from agglomerating in the kiln and affecting the quality.

IV. Sludge Ceramsite Technology

Municipal sludge after concentration and dewatering contains a large number of pathogens, parasites and harmful substances (such as heavy metals, organic compounds, etc.). The principle of “reduction, stabilization, harmlessness and resource” must be followed in the treatment process to avoid secondary pollution to the environment. Dry sludge is transported to dry sludge hopper by belt conveyor and then roasted in rotary carburetor. When necessary, water vapor is introduced at the end of kiln to make sludge carbon. In the carburetor, 30% of sludge carbon is burned to ash. Sludge ash and other ingredients in raw sludge ceramsite are adjusted appropriately according to the actual situation. After metering and weighing accurately in the silo, the sludge ash is sent to the mixer by belt conveyor and hoist, and then it is extruded and granulated by roller granulator. The ceramsite body with qualified particle size and uniform size is screened out by roller. The material less than 3mm is returned to the mixer and roller granulator by hoist. Drum sieve re-granulation and screening. Formed ceramsite body enters ceramsite kiln through feeding device to complete calcination. The finished ceramsite is cooled by heat exchanger and transported to finished product warehouse by zipper machine for storage and transportation.

Luoyang Building Material and Architectural Design and Research Institute, based on many years of industry experience, has successfully developed the preparation process of sludge carbon or sludge ceramsite and core equipment with independent intellectual property rights, realizing “one set of equipment, two products”, and completing the first set of equipment development and standard demonstration in China. Our institute can provide a series of services, such as feasibility study report, design, general package, production upgrading, intelligent transformation, etc. It can provide customers with solutions tailored to local conditions and scientific and reasonable production line process.

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Six Problems Considered in Design and Selection of Sandstone Aggregate Production Line

Sandstone aggregate production line is one of the most upstream production lines in national infrastructure, which provides indispensable raw materials for various types of infrastructure. However, in the production process of sand aggregate, most of the production lines can not meet the original design needs, and at the same time, there will be some problems more or less. Below for you to explain the six common problems, and the corresponding solutions. This will be helpful to the design and selection of production line, so as to avoid the influence of wrong concepts on the later production line operation.

I. Equipment Selection

In the process of investing in production line, many investors directly use a set of equipment needed by other production lines, regardless of the differences and characteristics of raw materials.

However, some equipment is not suitable, such as crusher is divided into hammer type and counterattack type. In a short time, the required equipment output can be achieved barely. After the equipment is put into operation for a period of time, a large number of problems have appeared one after another, such as serious wear and tear of equipment wear parts, frequent replacement, increased power consumption, reduced output, increased maintenance costs and so on.

Such problems are generally difficult to adjust by changing the process. Replacing equipment is the only solution at present.

II. Material bin or silo

1. Coarsely broken feeding bin

The common problem is that the side outlet of the warehouse is designed as a rectangular “door” structure. There is a dead angle between the warehouse and the outlet. The material discharging is not smooth enough. The bulk material is easy to accumulate here, which affects the normal feeding.

Improvement measures: Place a excavator beside the feeding port to clean up the accumulated material at any time; in the off-season of the market, transform the side outlet of the feeding bin into trapezoidal “inverted eight” structure in order to eliminate the dead corner of the accumulated material.

2. Medium and Fine Breakage and Sand Buffer Silo

The common problem is that the bottom of the warehouse is designed as a flat-bottomed steel warehouse structure, because the overall material pressure at the bottom of the warehouse is large, during the operation of the production line, there will be serious deformation and subsidence at the bottom of the steel warehouse, which will lead to potential safety hazards.

Improvement measures: reinforcement of the bottom structure; design units try to avoid using flat-bottomed steel silo structure in the design, if inevitable, try to choose the bottom of the silo as concrete structure.

3. Product Storage

Product warehouse generally adopts concrete storage form, which has large storage capacity and is safe and stable. But some enterprises choose steel warehouse to store sand and aggregate, so it is necessary to regularly check the wear condition of steel warehouse and carry out wear-resistant treatment.

4. Stone Powder Storage

The common problems are the wetness of stone powder produced in rainy weather and the difficulty of discharging stone powder from paste storehouse.

Improvement measures: Install several air guns below the reservoir body, and use compressed air to loosen the stone powder in the reservoir; design units should try to control the stone powder storehouse not to be too large in design, and design flow aids, inflatable boxes or air guns in the cone part of the reservoir.

III. Material transshipment gap

1. Rough breaking outlet

Coarse breaking equipment has a certain thickness of concrete foundation, and the gap between the outlet and downstream conveyor belt is large, and after coarsening, the bulk of the material is less than 300 mm. These stones are directly hit on the belt conveyor, and there will be phenomena such as breaking the buffer roller and tearing the conveyor belt by the roller carrier.

Improvement measures: The buffer roller of downstream belt conveyor is replaced by buffer bed, and the structure of discharge chute is changed to reduce the impact on downstream equipment. In addition, if the drop is very large and the layout space permits, the impact on downstream equipment can also be reduced by adding buffer feeder (such as vibration feeder).

2. Vibrating Screen Feed Gate

In order to ensure sufficient overhaul space above the vibrating screen, or to separate the material between the conveying equipment and the vibrating screen “one to two”, there will be a large drop when the material enters the vibrating screen, and the impact of the material on the screen plate in operation will cause rapid wear and tear of the screen plate.

Improvement measures: adding waste belt conveyor tape to the impact position of the screen plate, and rationally adjusting the slide form to reduce the impact and wear of the screen plate.

IV. Environmental problems

After the formal design of production lines, environmental protection can basically meet the requirements of the national standard, but individual production lines in the vicinity of the second break impact crusher, finished goods loading garage near bulk dust.

Improvement measures: 1) Firstly, according to the number and location of dust collection points, the selected dust collector specifications, for the dust near the impact crusher, if the designed dust collector air volume is enough, then setting dust collection points before and after the crusher discharge points can effectively reduce the dust raised here. 2) for the fugitive dust near the bulk of the finished product store, if the air volume of the designed dust collector is sufficient, and the bulk dust collector is collected through the top dust collector, a centrifugal fan can be added between the connecting air pipe of the bulk machine and the top of the storehouse to enhance the dust collecting efficiency of the top dust collector, and the addition of water spray dust near the unloading port of the bulk machine can effectively reduce the dust collection efficiency. Fugitive dust.

V. Collection and transportation of stone powder (< 0.075mm)

The dust collecting powder of the production line is collected directly on the downstream conveyor belt, so there are some problems, such as repeated reverse transportation, secondary dust, high content of stone powder in the product, and so on. In addition, there are dust spills caused by improper sealing of the belt conveyor’s guide trough and rain cover, or rain leaks in cloudy and rainy days, which make the stone powder moist and eventually cause the phenomenon of paste storage.

In the production line, stone powder is conveyed by air conveying chute. There is a problem that the permeable layer of the chute is sealed when stone powder is wet in rainy days, and the material can not be conveyed.

Improvement measures: dust collected by dust collectors in the production line or at least in the later stage of the process will be transported to the stone powder storehouse by zipper and hoist equipment separately.

VI. Other Issues

1) When the vibration screen starts, the load is large, which easily causes the gear wear or damage of the exciter seriously. Improvement measures: Properly adjust the installation angle of the equipment, and increase the frequency converter to start slowly.

2) The inaccuracy of the basic data collected during the design results in the small selection of individual conveyor belts, which affects the production capacity of the production line. Improvement measures: by replacing the drive system to improve the belt speed of the belt conveyor, and then improve the conveying capacity of the belt conveyor.

3) Dust leak and material leak at the connection between the import and export of vibration equipment. The canvas soft connection used is not durable and frequently replaced. Improvement measures: Soft connection is made on site with waste belt conveyor tape, which has long service life and good sealing effect.

Luoyang Building Material and Architectural Design and Research Institute is a professional building material and building double-grade design and research institute. It has more than 20 years’experience in mineral material research. According to the needs of customers, our institute can provide a series of services, such as feasibility study report, design, general package, production improvement, intelligent transformation, etc. It can provide customers with solutions tailored to local conditions, scientific and reasonable production line engineering. Art can not only meet the output requirements of process design, but also save resources, save energy and protect environment. It can also greatly reduce the failure rate of equipment, reduce the loss of equipment and the replacement frequency of spare parts, and realize the continuous growth of economic benefits.

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