I. Introduction
With the coming of the next semester of senior year, under the arrangement of the school, our students majoring in environmental engineering conducted the last internship in the university-graduation internship. Graduation practice is another important practice link based on environmental monitoring practice and production practice after we have completed all professional courses and elective courses, and it is also an organic part of graduation design. Its purpose is to consolidate, verify and strengthen what we have learned, cultivate the ability to integrate theory with practice and comprehensively apply what we have learned to solve practical problems, and lay a good foundation for our upcoming graduation project and future work.
1, through graduation practice, we can link the theoretical knowledge learned in class with actual production, deepen our mastery and understanding of professional knowledge, make full use of the favorable conditions of the practice base, cultivate the ability to analyze engineering examples, and strengthen the comprehensive ability to find, analyze and solve problems.
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2. Through graduation practice, we can gain practical knowledge of environmental engineering design, operation management, new technology and new equipment development, understand the operation and existing problems of these processes and equipment, collect necessary information for graduation thesis design, and solve possible problems in design.
The main contents of this internship include:
1, data collection: ① general situation of the internship unit: history, production mode and scale, process characteristics and main products of the workshop; (2) Understand the geographical environment of the internship site, including the plan and elevation of the factory and its surroundings, as well as relevant hydrological, meteorological and geological data of the factory and its surroundings; (3) To understand the emission laws, characteristics and pollution status of pollution sources; (4) The quality of the inlet and outlet water of the internship factory.
2. Process practice: ① Master the detailed process flow or treatment method of sewage treatment in the practice factory and draw the process flow chart of the practice factory; (2) Master the layout and characteristics of various process equipment and structures (structural form, detailed structure, performance and size of process equipment, control mode), understand the relevant layout principles, draw the actual layout of main equipment or structures, and mark the actual size; (3) To master the operation process of main working procedures and understand their main control indexes and changes; (4) Understand the equipment and usage of various monitoring and control instruments in the laboratory and purification process; ⑤ The dosage and price of each consumption index during the treatment; ⑥ Understand the labor capacity, staffing and whether to pay sewage charges for each position; ⑦ Actively participate in on-site technical transformation and other activities.
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3. Reading drawings: Reading factory construction drawings, combining drawings with actual projects, so that we can understand and master the contents and expressions of construction drawings and lay the foundation for graduation design.
Second, the factory profile
(1) Introduction of Daqing City
Daqing is an important oil industrial city in China, which is famous for its oil in the whole country and the world, and it is also a new modern comprehensive city.
Daqing is located in the west of Heilongjiang Province, China, in the middle of Songnen Plain, 0/59 kilometers away from Harbin, the capital city of Heilongjiang Province, and its geographical location is12419'-12512' and 45 46'-46 55 north latitude. There are five districts and four counties in the city, with a total area of 2 1 000 square kilometers and a total population of 2.622 million. Among them, the urban area is 5 107 square kilometers and the population is 1 184000. Daqing ranks first in the country in terms of oil and gas resources. Accumulated proven petroleum geological reserves are nearly 6 billion tons and natural gas is more than 50 billion cubic meters. In the next 20 years, 554.38 billion tons of oil and 20-30 billion cubic meters of recoverable natural gas will be added. Geothermal resources are abundant. The static reserves of hot springs in Lin Dian, China reach 654.38+08 billion cubic meters, with high temperature, rich in minerals and trace elements, which has extremely high development and utilization value and prospects.
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Since the development of 1960, Daqing Oilfield has become the largest petroleum production base and an important petrochemical base in China. Over the past 44 years, the cumulative production of crude oil 18438+ billion tons, accounting for about 47% of the total onshore crude oil production in China during the same period. Daqing has formed an annual production capacity of oil refining15.7 million tons, ethylene 480,000 tons, urea 560,000 tons, acrylic fiber 90,000 tons, synthetic resin 660,000 tons, paraffin wax 2 12000 tons and lubricating oil 450,000 tons. In addition to the oil and gas industry, Daqing's petrochemical products deep processing industry, electronic information industry, building materials industry, pharmaceutical industry, tourism and other continuing industries have also developed very rapidly. There are more than 0/500 industrial enterprises and more than 2,700 kinds of products in the city. The output of fresh milk products, pipes and plastic woven products ranks first in China, and a number of famous and excellent products sell well in domestic and foreign markets. The annual succession industry is oriented by high technology, and the annual high-tech industrial development zone is the only national high-tech industrial development zone in China relying on the advantages of petroleum and petrochemical industry. Since the establishment of 10, it has attracted more than 100 foreign-invested enterprises from10 countries, identified 260 provincial-level high-tech enterprises, and realized the total income of technology, industry and trade of more than 70 billion yuan.
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Dongcheng District is located in the north of Daqing City, west of Binzhou Railway. Its planned length from north to south is 15.2, and its width from east to west is 1 1.2, with a total area of 138.8. It is the political, economic and transportation center of Daqing City, and belongs to a variety of industries, high-tech industries and petrochemical industrial bases in Daqing City. This area is located in the middle of Songnen Plain, on the first step of Songhua River-Nenjiang River, with flat terrain, seasonal waterlogging depressions, low-lying swamps and permanent alkali bubbles.
(2) Brief introduction of sewage treatment plant in Dongcheng District of Daqing City.
As a key environmental protection project in Daqing City, the project of Dongcheng District Sewage Treatment Plant broke ground in April 2000, and was put into operation in June 2006 at 5438+0, covering an area of 6. 1 hectare, with catchment area of 138.8 square kilometers, laying intercepting pipes 19 kilometers, and installing 53 sets of main equipment, most of which.
Dongcheng District Sewage Treatment Plant is the first municipal sewage treatment plant in Daqing City, which adopts anaerobic and aerobic activated sludge dephosphorization process. The sewage treatment effect has reached the national first-class discharge standard GB-8976-96. The discharged water enters Shilipao Nature Reserve and flows into Songhua River via Anzhaoxin River.
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After the sewage treatment plant in Dongcheng District was put into operation, the pollution status of the wetland protection area with direct domestic sewage discharge in Dongcheng District was changed. In Dongcheng District, 4-5 tons of domestic sewage flows into the sewage interception pipe network every day, and the sewage is purified by Dongcheng District Sewage Treatment Plant and discharged into the wetland, which not only supplements the water quantity of the wetland, but also prevents the eutrophication of the water body, making the wetland a protected area with beautiful fish, lush water plants and flocks of waterfowl. The completion of sewage treatment plant in Dongcheng District plays an important role in maintaining ecological balance, purifying urban environment, improving people's quality of life and realizing sustainable economic development in Daqing City.
Three. Introduction of process flow and related structure
(a), the process flow
Dongcheng District Sewage Treatment Plant mainly treats the domestic sewage of Daqing residents and the rainwater in the plant area. Urban sewage is collected through the urban pipe network and flows into the intercepting pipeline of the treatment plant. See the following table for inlet and outlet water quality:
Inlet and outlet water quality measuring instrument
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stage
water
quality
Project primary treatment and secondary treatment
Water inflow ()
Effluent ()
Removal rate
(%) Water inflow ()
Effluent ()
Removal rate (%)
150 120 20 120 20 83.3
300 240 20 240 60 75
200 140 30 140 20 86
6.0 5.4 10 5.4 1.0 8 1.5
25 22.5 10 22.5 15 33.3
Sewage first enters the regulating pool of the treatment plant for water quantity regulation and water quality balance; Then lift it to the fine grid with a pump to remove impurities with larger particle size in the water and reduce the workload of subsequent structures. The water coming out of the grille enters the advection grit chamber, which makes the sand and heavy substances in the water settle down. The settled sand enters the sand-water separator for sand-water separation, while the sewage flows into the water distribution well. After buffering and balanced distribution in the water distribution well, it enters the amplitude flow primary sedimentation tank for sedimentation, thus removing most of the sludge in the sewage. Sludge is pushed into the sludge hopper in the center of the bottom of the tank by a sludge scraper, and then transported to the sludge storage tank. Then the sewage enters the A/O biochemical pool for aeration. The A/O biochemical tank is divided into two sections, A and B, to remove the organic matter and phosphorus in the water and reduce the ammonia nitrogen content in the water. The sewage after biochemical treatment finally enters the secondary sedimentation tank for activated sludge precipitation, and the precipitated sludge is pumped into the sludge pump tank by a sludge scraper and a sludge suction machine. Part of the activated sludge in the sludge pump tank flows back to the aeration tank (the reflux ratio is 1: 1.3), and the other part enters the sludge storage tank and then is pumped into the sludge dewatering room. Under the action of polyacrylamide, the mud cake is formed after pressure filtration and dehydration by belt concentration dehydrator, and is used for production after natural drying. The treated water is discharged into the twenty-mile bubble through the drainage well.
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Refer to the process flow chart:
(2), structures and equipment
1, pretreatment part
The pretreatment section includes five structures: regulating tank, grid room, advection grit chamber, distribution well and primary sedimentation tank. These structures are set to ensure that the A/O biochemical tank can effectively remove organic matter and phosphorus from sewage.
1. 1, regulating pool
The size of the regulating tank is 64.8×44.8 meters, and the function of the regulating tank is to regulate the quantity and even the quality of incoming water to ensure the smooth progress of the follow-up work. There are two pipes on the regulating tank, one is an overflow pipe, which can directly discharge sewage to the grid when cleaning the regulating tank, and the other is an overflow pipe. If the sewage flow in the regulating tank is too large, the sewage can be discharged along the overflow weir pipeline. There are 126 columns in the regulating tank, which are arranged in a square, and the distance between two adjacent columns is 4m. There are two manholes at the top of the pool with a diameter of d =1.00m; 8 exhaust holes with diameter D=0.2m; 15 agitator lifting holes with diameter d = 1.00 m, water inlet elevation 142.8m, and maximum water level 144m. . The main equipment is mixer and submersible pump.
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Submersible pump for regulating pool (4 sets)
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Parameter flow =87 1~936 m3/h=242~260L/s head = 9 ~10.5m.
Shaft power =35.7kw, allowed passing granularity = 120 mm.
Pump efficiency =75~78%
Motor power (rated power) =37kw output power =39kw
Power factor =0.86 rpm = 1448 rpm.
The protection grade is IP08 and the insulation grade is F ..
10m cable
Accessories: overheat protector, humidity detector, relay, lifting device and local control box.
Submersible pumps (4 sets) are used to lift the pumping station halfway.
run quickly
Parameter flow = 1620m3/h=450L/s water head =40m.
Shaft power =2 15.2kw allowable passing granularity =75mm.
Pump efficiency =82%
Motor power (rated power) =220kw output power =220kw.
Power factor =0.8 1 rpm = 1489 rpm.
The protection grade is IP08 and the insulation grade is F ..
10m cable
Accessories: overheat protector, humidity detector, relay, lifting device and local control box.
1.2, grille room
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Grille room is used to remove coarse floating objects or suspended impurities in sewage to prevent subsequent treatment facilities from being worn or blocked. Therefore, the grid is a particularly important structure in the pretreatment process. The main equipment is grid machine and sand-water separator.
The grating machine adopts RSM-26- 180-5 single-step grating (two, one for use and one for standby) as a whole structure, which is composed of fixed grating bars and movable grating bars at intervals. The fixed grating is fixed on the frame, and the pollutants intercepted by the fixed grating are gradually lifted to the slag discharge port at the top of the grating from bottom to top.
Grille technical data:
Processing capacity: Q=4500m3/h (Daqing Project 1250m3/h)
Maximum water level in front of grille: 2200mm; maximum water level behind grille: 2000mm.
Total height of grille: 3285mm grille length: 3580 mm.
Effective length of grille: 3280mm; width of grille: 1885mm.
Effective floor space width of grille:1755mm; Width of grille opening: 2565mm.
Grating strip thickness: 3 mm Grating strip gap: 5 mm..