College: College of Education
Category: building materials 060 1
Name: Tong Jianbin
Student number: 20062160011.
Instructor: Ying Debiao Qiu Qiong
Practice location: Ningbo kehuan new building materials co., ltd.
Internship time: July 2008 16-July 26, 2008.
1. Internship goal
The purpose of production practice is to make students understand the production process, production equipment and production organization of the factory, master the concrete production process of cement raw materials and the formation process of cement clinker, master the working principles and functions of various production equipment, lay a perceptual knowledge for subsequent professional courses, understand the society, cultivate the ability of independent thinking and work, and collect necessary information and data for future graduation design.
2. Company profile
Ningbo kehuan new building materials co., ltd (formerly Ningbo shunjiang cement co., ltd), located in the northern suburb of Yuyao city, Zhejiang province, was founded in 1975. Up to now, it is a large-scale cement enterprise covering an area of more than 400 mu and the backbone enterprise of Ningbo Fidelity Co., Ltd., a listed company. The company has 562 employees and fixed assets of 638 million yuan. It has passed ISO900 1 quality management system certification and ISO 1400 1 environmental management system certification, and won the title of Zhejiang famous trademark and Ningbo famous trademark. It is an advanced energy-saving enterprise in Zhejiang Province and one of the top ten benchmark enterprises for energy conservation and emission reduction in Zhejiang Province. Its "Shunjiang" brand cement is a national inspection-free product.
2. 1 corporate culture
Enterprise spirit: high efficiency, pragmatism, hard work and transcendence.
Quality policy: optimize procurement, optimize operation and provide quality ex-factory service.
2.2 Enterprise advantages
Production scale-The company newly built a dry-process cement production line with a design scale of 2,500 t/d and an actual production capacity of 3,000 t/d, which is the second batch of "double high and one excellent" projects in China. At present, it is the only new dry cement production line in Ningbo, with an annual output of 2 million tons of cement grinding and 400,000 tons of slag powder. The main sales place is Ningbo.
Product category-
■ General purpose cement: ordinary portland cement, composite portland cement, portland cement clinker, etc.
■ Special cement: marine cement, road cement, pipe pile cement, low alkali cement, emergency repair cement, medium and low heat cement, grouting cement, etc.
■ New building materials: slag powder and composite cementitious materials.
Main product features-
■ Ordinary cement: stable performance, small fluctuation, high strength, good workability and strong adaptability to additives.
■ Marine cement: high chloride ion penetration resistance, low hydration heat, impermeability, frost resistance and slight expansion.
■ Pipe pile cement: autoclaved, the strength of pipe pile reaches above C80, the bending resistance is good, the construction performance is excellent, the production cycle of pipe pile is shortened, and the production cost of pipe pile is greatly reduced.
■ High-performance concrete made of high-performance slag powder and ordinary cement has high fluidity, high strength, high wear resistance, high durability and excellent resistance to chloride ion penetration.
Cleaner production-The company is the first batch of comprehensive resource utilization enterprises in Ningbo and the first batch of cleaner production audit pilot enterprises in Zhejiang Province. In order to reduce pollutants from the source, all raw material storage and transportation equipment on the production line are closed. According to the monitoring by the environmental protection department, the emission concentration of waste gas under standard temperature and pressure is below 20mg/m3, which is far lower than the national standard 100mg/m3, and unorganized emission is effectively controlled. In the process of cement production, clean production is realized, and solid waste resources, including fly ash, slag, cinder and coal gangue, are actively utilized, with an annual profit of nearly 6,543,800 tons. The company has also been awarded the honorary titles of Zhejiang Green Enterprise and Zhejiang Advanced Typical Enterprise in Pollution Control.
Circular economy-The company is in a leading position in solid waste treatment in China. With the support of Ningbo Environmental Protection Department, the company cooperated with China Institute of Building Materials, Tsinghua University and other relevant units to carry out the experimental research on the project of "Harmless Comprehensive Utilization of Industrial Sludge Containing Heavy Metals", so that the industrial sludge from electroplating and stainless steel industries can be disposed at high temperature in the cement rotary kiln without causing secondary pollution to the environment. It is the only enterprise in Ningbo that uses a new dry cement kiln to treat industrial waste. It has become an important link for Ningbo to build an eco-city to transform the enterprise from a pure cement production enterprise into a solid waste (including hazardous solid waste) disposal unit. At present, it has been selected as a demonstration cement enterprise of Sino-Norwegian cooperation project "Environmentally sound management of hazardous waste and industrial waste disposal in China cement kiln".
Energy saving and consumption reduction—
■ In 2006, the company was listed by the National Development and Reform Commission as one of the "Energy Saving Thousand Talents Action" enterprises in China.
■ The first pure low-temperature waste heat power station in Ningbo was built by using the waste heat from the kiln head and kiln tail of the new dry-process cement rotary kiln, with an annual power generation of 28.08 million kWh and an annual saving of nearly 654.38+/kloc-0.0 million tons of standard coal.
■ Equipped with four sets of circulating water treatment systems, with a circulation rate of over 96%.
■ Equipped with lubricating oil filtration system to recover waste oil and dirty oil, saving more than 100 tons of lubricating oil every year.
■ Using the waste heat of kiln clinker to dry slag, fly ash and other mixed materials, saving 2,880 tons of standard coal and 360,000 kWh of electricity.
3. Cement production process
3. 1 Layout of the whole plant
3.2 New dry cement production method
Generally, suspension preheating and pre-decomposition technology are taken as the core, and modern science and technology, such as mine computer-controlled network mining, raw meal pre-homogenization, new efficient and multifunctional extrusion grinding technology, new mechanical powder conveying device, new heat-resistant, wear-resistant, fire-resistant and heat-insulating materials and IT technology, are widely used in the whole process of cement dry production, so that cement production has high efficiency, high quality, resource saving, clean production, environmental protection requirements and large-scale process equipment.
The characteristic of dry production is that raw meal powder is directly sent to the kiln for calcination, and the moisture content of raw material in the kiln is generally only 1% ~ 2%, which saves a lot of heat needed for drying raw meal. In the past, the hollow rotary kiln was used in dry production, and the heat transfer efficiency in the kiln was low, especially in the decomposition zone with high heat consumption, and the thermal efficiency of the dry hollow kiln was not improved much. The raw meal powder prepared by dry method is not easy to mix evenly, which affects the quality of clinker. Therefore, wet production was the main method in the 1940s and 1950s, and the air stirring technology and suspension preheating technology of raw meal powder appeared in the 1950s, and the pre-decomposition technology, raw meal pre-homogenization technology and raw meal quality control technology were born in the early 1960s. Now dry production can completely prepare raw materials with uniform quality. The new precalcining kiln moves the preheating of raw meal powder and carbonate decomposition to the suspended state outside the kiln, which has high thermal efficiency and reduces the load of the rotary kiln. Low heat consumption not only improves the thermal efficiency of rotary kiln from about 30% to over 60%, but also expands the production capacity of kiln. At present, the standard kiln type is 3000 tons/day, and the largest is 10000. There are several specifications of 700t/d, 1000t/d, 2000t/d and 4000t/d in China, which are gradually developing to large scale. The invention has the advantages of good pre-combustion of raw materials, high temperature in the kiln, fast cooling speed of clinker, high silicic acid rate, high saturation rate and aluminum-oxygen ratio, and high clinker strength. Therefore, suspension preheating and precalcining kilns are now collectively called new dry kiln or new dry production line, and new dry production is the future development direction. The new dry kiln has a large scale, relatively high investment and high requirements for technical level and industrial supporting capacity. If the conditions are not met, it will be difficult to develop normally.
3.2. 1 new dry cement production process
limestone
Mine exploitation
Sand and gravel batching in vertical mill raw material homogenizing bin (fluorescence analysis) kiln tail preheater
slag
Clinker silo cooler rotary kiln calciner
Factory-packaged cement-cement mill mixture
plaster
3.3 Process flow chart of raw meal section of cement plant
Limestone → plate feeder → single-stage hammer crusher → belt → stacker → reclaimer → belt → batching station → vertical mill →O-Sepa classifier → pneumatic conveying pipeline and belt hoist → raw meal homogenizing bin.
3.4 Clinker calcination
3.4. 1 Raw material preheating and precalcining system
The preheating and decomposing system of Shunjiang Cement Plant is a five-stage cyclone preheater and a decomposing furnace. The tertiary air at the kiln head enters the calciner, and there are two coal injection pipes on the calciner to complete the supply of pulverized coal. Relevant parameters are as follows:
The size of the calciner is φ5. 1×30m.
The dimensions of the five-stage preheater are as follows:
c 12—φ4600mm； c 2 1—φ6500mm； c 3 1—φ6800mm； c 4 1—φ6800mm； C 51-φ 6800 mm.
The pre-decomposition system not only makes rational use of kiln head waste gas and saves energy, but also pre-heats and decomposes the materials, which provides the premise for the calcination of the materials and improves the quality and production efficiency of clinker. Rotary kiln is divided into drying zone, preheating zone, decomposition zone, solid reaction zone, firing zone and cooling zone. Shunjiang Cement Plant mainly adopts φ4.0×60m rotary kiln with an inclination of 4%. The transmission device is a single-drive DC motor, and the rotating speed of the kiln body is 0.4 1 ~ 0.42r/min.
3.4. 1. 1 process flow
Flowchart of clinker calcination stage
3.5 Clinker cooling
The outlet temperature of cement clinker is about1100 ~1300℃. It is of great significance to fully recover the heat taken by clinker and preheat the secondary air to improve the combustion speed, fuel temperature and thermal efficiency of kiln and cooler. Cooling clinker has a good effect on improving clinker quality and grindability, and well-cooled clinker can ensure the safe operation of equipment. Grate cooler is used in Shunjiang Cement Plant.
3.6 Preparation of Cement
3.6. 1 cement grinding
Cement grinding is the last process of cement manufacturing, and it also consumes the most electricity. Its main function is to grind cement clinker (and gelling agent, performance adjusting material, etc.). ) to a suitable particle size (expressed by fineness, specific surface area, etc.). ), form a certain particle gradation, increase its hydration area, accelerate the hydration speed, and meet the requirements of setting and hardening of cement paste.
3.6.2 Open circuit and closed circuit system of cement grinding system
Open circuit system: In the grinding process, the material passes through the mill once, which is called open circuit system. Closed-circuit system: It is called closed-circuit system when materials are crushed, products are separated by classification equipment and returned to the mill for grinding. Closed-circuit grinding is widely used in cement grinding system of ball mill because it is beneficial to cement quality and has good technical and economic effects.
Cement packaging
Cement can be transported in bags and in bulk. Feed must first pass through the rotary sieve to screen out iron impurities mixed in the mud to prevent blockage and ensure the normal operation of the packaging machine. A small packaging bin is arranged between the packaging machine and the rotary screen to stabilize the material flow and is not used for storage. Packaged bagged cement generally falls directly into the flat belt conveyor under the packaging machine and is sent to the finished product warehouse.
4. Main host equipment of the whole plant
1, plate feeder
Model: 2200×9750mm；; ; The slope is 20; The conveying speed is 0.0 1-0.09 m/s; The maximum conveying capacity is 800 t/h; The maximum feed particle size is1500mm.
2. Hammer crusher
Model: MB56/75；; ; Output: 500-600t/h; Discharging granularity ≤ 75mm; The maximum feed particle size is1500mm.
3. Belt conveyor
Model: TD75 groove b1000×152500mm; The maximum conveying capacity is 600 t/h; The tape speed is1.25m/s.
4, pulse bag filter
Model: PPCS 64-6; The treated air volume is 26700m3/h; The total filtration area is 372m2, and the net filtration area is 310m2; The total number of filter bags is 384; Import dust concentration <1000g/nm3; Outlet dust concentration <1000 mg/nm3; The equipment bears a negative pressure of 5000 Pa.
5, screw conveyor
Model: 300mm；; The conveying capacity is 30m3/h.
6. roots blower
Model: JSD125; ; The air volume is 7.07m3/min; ; Wind pressure 49kpa；; The rotating speed is 970 rpm.
7 air conveying tank
Model: xz250×11880; Conveying materials: fly ash; The inclination angle is 6; The transportation capacity is10t/h.
8. Rotary kiln
Size: φ 4.0× 60m; ; The inclination is 3.5%; The maximum rotation speed of the kiln body is 3.96 rpm; The production capacity is 2500 tons/day.
9. Vertical mill
Model: MPS3750B；; The production capacity is 180 tons/hour.
10, coal mill
Type: air-swept coal mill; Specification φ 3.4× 6+3; The production capacity is18t/h.
1 1, raw mill
O-Sepa classifier
Model: n-2000; Total weight19183kg; Air volume: 2000m3/min; ; Feed rate: 400 tons/hour; Motor power132kw; ; The cement production capacity is 72 ~120 t/h.
12, cement mill
Model: φ φ 3.8×13m; ; The effective volume of the cylinder is132.3m3; ; Ball loading173000 kg; ; Mill speed 16.3 rpm; The main motor power is 2500kw；; The equipment weighs 226304 kilograms.
13, centrifugal fan
Model: 64-739d；; Spindle speed is 1403 rpm.
5. Cooperation among enterprises
As a backbone enterprise under the listed company Ningbo Fidelity Co., Ltd., Ningbo Kehuan Building Materials built the first and only new dry cement production line with a daily output of 2,500 tons in Ningbo as early as the end of 2003, with an annual output of 2 million tons of cement. However, because Ningbo Kehuan Building Materials is located in Yuyao City, the limestone resources in the east coast of Zhejiang Province are scarce, and the constraints of geography and resources on the development of enterprises are very serious. The scale of enterprises can only be maintained at the current level, and there is no room for further expansion of production.
Mengzi Yingzhou Cement Plant was established in 2005 with a registered capital of 7 million yuan. The enterprise is located in Bise Village, Caoba Town, Mengzi County, Honghe Prefecture, Yunnan Province. It is rich in limestone resources. There is a mechanical shaft kiln cement production line with an actual cement production capacity of 200,000 tons/year and a cement grinding capacity of 300,000 tons/year. Mengzi County, located in the south of Yunnan, is the main passage from southwest China to Viet Nam. According to the development plan, infrastructure projects under construction and proposed in Honghe Prefecture and Mengzi County include railways, expressways and airports. The capacity of cement market exceeds 2 million tons/year. At present, there is no new dry cement production line in the county, but only two small cement enterprises, most of which need to be transferred from outside the county and state, and the market gap is large.
At the beginning of 2007, under the matchmaking of China Cement Association, Ningbo Kehuan Building Materials and Mengzi Yingzhou Cement made many visits and communication, and gained a * * * understanding of the assets reorganization of both parties, believing that the cooperation between the two parties has a good prospect. Relying on the advantages of Ningbo kehuan building materials in capital, technology and management, relying on the scientific research advantages of Ningbo kehuan building materials in the field of comprehensive utilization of special cement and solid waste, and learning from the successful experience of Ningbo kehuan building materials in establishing an environmental protection enterprise. The technical transformation of Mengzi Yingzhou Cement will make it a production base integrating cement manufacturing, special cement and research and development of new building materials in southern Yunnan, so that Mengzi Yingzhou Cement can get rid of extensive production mode, reduce pollutant emissions while increasing production, and use a large number of local solid waste resources to produce ordinary cement, special cement and new building materials, protect the environment and change cement production from "pollution" to "zero pollution" or even "negative pollution".
After the reorganization of Ningbo Kehuan Building Materials and Mengzi Yingzhou Cement Assets, it will invest 600 million yuan to build a cement base with an annual output of 2 million tons in Mengzi County, in which the first phase of the project will invest 400 million yuan to build a new dry-process cement clinker production line with an annual output of 2 100 tons.
The asset reorganization of Ningbo Kehuan Building Materials and Mengzi Yingzhou Cement has set a good example for Zhejiang businessmen to avoid market infighting and realize the strategic shift of enterprise development.
6. Concluding remarks
Internship is a necessary experience for every college student. It enables us to understand the society in practice, learn a lot of knowledge that we can't learn in class, broaden our horizons, increase our knowledge and lay a solid foundation for our further social development. Through production practice, we have learned the knowledge of production practice, strengthened the concept of labor and cultivated the skills of production practice. Practice is an attempt to apply the theoretical knowledge we have learned to practice. Finally, I sincerely thank Ningbo Kehuan New Building Materials Co., Ltd. for providing us with this internship opportunity, and also thank Ying Debiao and Qiu Qiong for their hard guidance.
I'll give you mine