Countermeasures to improve the efficiency of construction land in waterworks.

The following are some countermeasures to improve land use efficiency in the construction of waterworks brought by Zhong Da Consulting for your reference.

With the establishment of the socialist market economic system and the establishment of the paid land use system by the state, people gradually realize the use value of land. Especially in recent years, the growth of urban population, the improvement of living quality and the rapid economic development have expanded the demand for land in cities. Therefore, improving the comprehensive efficiency of urban land use has become a growing concern of the society.

Water plant is one of the infrastructures of urban construction. Due to the rapid growth of urban water consumption, in recent years, many cities urgently need to build or rebuild water plants. How to improve the utilization rate of land in the design of newly-built or rebuilt waterworks is one of the problems that water supply engineers should seriously consider. Through the work practice in recent years, the author realized that the way to solve the problem can be found by improving the scientific and technological content of process design and adopting advanced equipment. This paper discusses this and puts forward four countermeasures to solve similar problems.

1. Replace the water distribution well with the flow regulating valve to reduce the water distribution area.

In order to ensure the constant water inflow and stable water inflow pressure of water purification structures, whether the raw water is taken from groundwater or surface water, whether it is transported to the water purification plant by gravity flow or pressurized by water pump, it is necessary to distribute water before entering the water purification structures. For many years, the conventional practice is to set up water distribution overflow wells in front of water purification structures. Because the water distribution overflow well has no special equipment, it is convenient to maintain and manage, and it is also welcomed by users. However, its floor space has become the focus of water plant design. In recent years, the use of flow control valve provides a new way for the improvement of water distribution mode. Because of its advantages of less investment, small floor space, convenient adjustment of head and water volume, and no waste of overflow water, it has attracted more and more attention from designers. Take the third phase project of Dongguan No.3 Water Plant designed by the author in recent years as an example. The scale of the first phase project is 250,000 cubic meters/day; The scale of the second phase project is 350,000 m3/d; The scale of the third phase project is 500,000 m3/d, and the water source is Dongjiang water, which is lifted by the water intake pump and transported to the water purification plant through the water pipeline. As the water plant is built by stages in different periods, the water pipes from the pump house to the water purification plant are DN= 1600, DN= 1800 and DN=2200, with a length of about 2km, and are connected in parallel with the first, second and third phases of the project. As there are 8 pumps in the water intake pump house, 7 of which are used for 1 standby, it is difficult to use 7 pumps to form three groups to deliver 250,000 m3/d, 350,000 m3/d and 500,000 m3/d water to the water purification structures at each level of the water purification plant, so it is necessary to redistribute the flow in the water purification plant according to the scale of the first, second and third levels. If the water distribution overflow well is set as usual, it needs to invest 2 million yuan, and the water distribution overflow well covers an area of about 3.7 mu. However, due to the shortage of land in Dongguan, it is impossible to set up water distribution overflow wells. Therefore, in the design, the flow regulating valve is used instead of the water distribution overflow well, that is, the flow regulating valve is added at the ends of the three water delivery pipelines respectively, and the opening of the flow regulating valve is controlled by the flowmeter signal behind the valve to distribute water for the first, second and third water purification structures. After calculation, the maximum pressure difference before and after the first, second and third stage flow regulating valves is less than 10m, and the butterfly valve selected completely meets the design requirements. Butterfly valve equipment only needs to invest 800,000 yuan, saving about 6,543,800 yuan, and reducing the area by about 3 mu.

Similarly, in some projects that use reservoir water as water source and use gravity to flow to water distribution plants, flow control valves are also used to solve similar problems. For example, the second phase project of Beijing No.9 Water Plant and the reconstruction and expansion project of Zunyi Northern Suburb Water Plant, the flow control valve has played a successful role.

2. Overlap water purification structures to reduce the floor space of water purification structures.

According to the traditional design idea, there are three basic forms for the layout of water purification structures along the process: ① linear; ② Angle-folding type; (3) transformation. The characteristic of these forms is that all the structures are on the same plane, end to end, which obviously covers a larger area. Although this arrangement structure is simple in construction and leaves room for expanding reproduction in the future, it is still the first choice in those areas with sufficient land area. However, in some old waterworks, where there is not enough building area available, several water purification structures can be superimposed to reduce the plane area and turn to spatial development. The design of superimposed pool can not only save land, but also make full use of the natural law of water flowing downwards, reduce the head loss between structures and facilitate centralized management. ?

Take the reconstruction and expansion project of water plant in the northern suburb of Zunyi City as an example. The reconstruction and expansion project of the water plant in the northern suburb of Zunyi City is 654.38+ 1 100 million m3/d. If the water purification structures are arranged end to end along the process, the water purification plant covers an area of about 65 mu. However, if a clean water tank is built under the advection sedimentation tank, and the mixing well, grid flocculation tank, advection sedimentation tank and clean water tank are designed as overlapping tanks, which are connected with the filter tank and water distribution pump house through pipelines, the floor area will be reduced by about 16 mu. ?

The third phase project of Dongguan No.3 Water Plant also adopts the way of overlapping water purification structures, and combines the water purification structures with a scale of 500,000 m3/d, such as grid flocculation tank, advection sedimentation tank, V-type filter and clean water tank, into a group water purification structure, covering an area of only 43 mu. The specific method is to build a filter between two flocculation sedimentation tanks in series and a clear water tank under the advection sedimentation tank. The plane size of the group water purification structure is 150m× 135m. The design parameters of the superimposed pool in the Third Water Plant are as follows:

(1) The grid flocculation tank and advection sedimentation tank are superimposed on the clear water tank. The grid flocculation tank and horizontal sedimentation tank are divided into two series, and each series is divided into two groups, with the treatment capacity of 250,000 m3/d for each series and 1.25 million m3/d for each group, which can operate independently. Flocculation tank and sedimentation tank are arranged in front and back, clear water tank and sedimentation tank are arranged up and down, and flocculation, sedimentation and clear water tank form a superimposed tank.

The plane size of each group of flocculation tanks is 20.4m× 15m, which is divided into four units, and each unit is divided into three sections of *** 12 units, with the plane size of a single unit of 2.3m×2.3m and the flow rate of the first section of 0.27m/s; In the second stage, the net flow rate is 0.20 m/s; In the third stage, there is no air distribution plate, the empty tower speed is 0.073m/s, and the total residence time of flocculation tank is 12min.

The plane size of each group of advection sedimentation tanks is 20.4m× 130.4m, the effective water depth is 3.2m, the horizontal velocity is 24mm/s, and the residence time is10.5 h. A siphon suction machine is arranged at the top of each group of tanks to suck the sludge at the bottom of the tanks into the sludge discharge port.

There are 1 clear water tanks under each series of sedimentation tanks. Because the water supply in the water distribution pump room of the water plant is uniform, the capacity of the clear water pool does not need to be too large. The total effective volume of the two fresh water tanks is 20,900 m3, and the residence time is1h. The plane dimensions of a single clean water tank are 1, 3 1m×44.8m, and vents are arranged on both sides of the tank wall.

(2)V-type filter. The filter and the sedimentation superimposed pool are combined into a group arrangement. The filter is located between two series of superimposed sedimentation tanks, and the filter and sedimentation tank use the upper walkway and the lower drainage channel. At the end of the filter are the equipment room and the control room. The filters are divided into two series, which are symmetrically arranged with a pipe gallery in the middle, and the water inlet and outlet channels are arranged on both sides of the box. The overall plane size is 1 17m×45m. Each series consists of 12 single cells, with a filtration area of 98m2, a design filtration rate of 9. 12m/h, gas washing strength18l/(m2 s) and washing strength.

Each pool is equipped with 600mm×600mm flat gate (adjustable opening), 600mm×600mm flat gate (common type), DN=500 outlet regulating valve, DN=350 flushing inlet valve and DN=500 flushing inlet valve, each with 1. They are all pneumatic valves.

There are 3 washing water pumps (2 for use 1 standby) in the machine room. What is the design water quantity? 14 15m3/h, design lift13.4m; ; Two blowers (1 standby), with design air volume 106m3/min and design air pressure of 0.4 bar (1bar =105pa); 2 air compressors (1 standby).

The filtering operation is controlled by the computer.

3. Adopt efficient equipment to increase the unit output of equipment and reduce the floor space.

After 1980s, with the introduction of foreign advanced technology and equipment, some technologies in water treatment in China have undergone qualitative changes. At present, negative pressure chlorination disinfection equipment with liquid chlorine as chlorine source has been popularized in newly built or rebuilt water plants, but it usually takes the form of natural vaporization of liquid chlorine. For example, the design scale of chlorination room in the first and second phases of Dongguan No.3 Water Plant is 600,000 m3/d ... There are 1 pre-chlorination points and 2 main chlorination points in the first and second phases respectively. Pre-chlorination is provided with four 40kg/h flow control chlorinators (2 for use and 2 for standby); The main chlorinator is equipped with six 20kg/h residual chlorine control chlorinators (4 for use and 2 for standby). The plane dimensions of chlorine dosing room and chlorine storage room are 30m× 10m. Because chlorine bottles are used for natural vaporization, * * * 20 chlorine bottles are arranged in a row, and 10 bottles are used as a group, and the two groups are standby for each other. The advantage of natural vaporization is to save electricity, but the chlorine warehouse occupies a large area. According to the data, a chlorine bottle of 1000kg produces 8kg/h at room temperature. When the dosage of chlorine exceeds 40kg/h, it is uneconomical to use natural vaporization, and it also brings problems to safety due to many pipeline connections. After the completion of the third phase project of Dongguan No.3 Waterworks, the scale will be increased from 600,000 m3/d to165438+100,000 m3/d. If natural vaporization is still used for chlorination, 36 online chlorine bottles (18) will be needed, and the two groups will be used as backup. In this case, it is economical and reasonable to adopt a high-efficiency liquid chlorine evaporator. The gas production of 1 liquid chlorine evaporator is usually 120-200kg/h, which is equivalent to the gas production of 15-25 chlorine bottles, but its floor space is less than 1m2. Two 200kg/h liquid chlorine evaporators were selected for the third phase project of Dongguan No.3 Water Plant, and the chlorination room was reformed according to the existing conditions.

(1) Use the original chlorinating machine, appropriately increase the chlorinating machine, and transform the chlorinating pipeline. The pre-chlorination point in the third phase is located at 1 on the main water inlet pipe, with the chlorination rate 1mg/L and the chlorination amount of 22.29 kg/h. It is considered that two 40kg/h flow control chlorinators will be reserved in the first and second phases, and the pre-chlorination machines will not be added in the third phase, but the chlorination pipeline needs to be reformed. There are two main chlorination points in the third phase, the chlorination rate is 2mg/L and the chlorination amount is 44.58 kg/h; In the third phase, 3 chlorinators were added (2 users 1 standby). After the first, second and third phases of the project are completed, there are three 20kg/h main chlorinators (2 for use/kloc-0 for standby) and six 40kg/h main chlorinators (4 for use and 2 for standby). There is a 13 chlorination machine in the chlorination room. The chlorinator was arranged compactly, and the design purpose was successfully achieved without expanding the chlorination chamber.

(2) Add a liquid chlorine evaporator. In the third phase, the chlorination system was redesigned according to the scale of 1 65438+1 0000 m3/d, and two evaporators were installed (1service,1standby). Due to the increase of liquid chlorine evaporators, the chlorine warehouse only needs two groups of working bottles (two bottles in each group are connected in parallel), which reduces the occupied area of working bottles. Under limited conditions, expand the existing chlorine warehouse (expand the original chlorine warehouse to the west 15.60m), and the storage days of the expanded chlorine warehouse are 14d. In addition, the selection of speed regulating pumps can reduce the number of pumps in the pump room, which is also a way to improve the unit output of equipment and reduce the occupied area by using efficient equipment.

4. Socialization of auxiliary production, reducing the occupied area of auxiliary production.

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