Problems needing attention in urban water supply and drainage

Analysis:

Taking residential water supply and drainage as an example

1 water supply system

1. 1 system design Each suite is an independent water supply system, and the water supply mode is: reservoir → pump → water tank → pressure reducing valve → water point.

This is a land-saving, energy-saving and easy-to-manage water supply scheme for high-rise residential buildings. It can not only meet the disadvantages that municipal infrastructure lags behind the rapid development of residential construction, but also avoid the impact on municipal water supply network; It can also solve the requirement of water storage in the early stage of fire protection in the Code for Fire Protection Design of High-rise Civil Buildings. Each residential building shares a reservoir, which is located in the underground garage. The single building is equipped with independent water pump, which has the advantages of independence, flexibility, easy management and favorable sales. The objective existence of water tank supply is one of the effective ways to solve the energy-saving problem of water supply system in high-rise buildings.

As for the problem of "secondary pollution" of water quality, the author thinks that besides reasonably determining the volume and arranging the location of water tanks in the design, creating necessary conditions for property management and water tank cleaning and maintenance, and establishing a good maintenance management system are important guarantees to avoid the problem of "secondary pollution" of water tank quality.

1.2 In the BA design community of water supply system, each single building is equipped with a pool, a water tank and a water pump, and the list is endless.

If the traditional management method is adopted, it will waste manpower and material resources and bring a lot of inconvenience to management. Therefore, the design of this community adopts BA system to monitor the running state and fault state of each pool, water tank and water pump. The automatic meter reading system in BA system solves many inconveniences caused by manual meter reading and serves residents better.

The BA design of water supply system mainly monitors and controls the operation state of booster pump, pool and water tank through signals such as liquid level, pressure and flow.

The specific control method is as follows:

(1) The remote metering mode of BA system is adopted for household water meters, which measures, charges, prints receipts, notices and statements on a monthly basis to provide timely consultation for residents.

(2) The roof water tank overflows, giving an alarm for over-high and low water level.

(3) Monitor the running state of household booster pump and give fault alarm.

(4) The underground pool and roof water tank should be regularly listed for cleaning and maintenance.

(5) Life booster pump shall be maintained regularly.

2 Hot water system The hot water for residential buildings is provided by their respective gas water heaters. Hot water for public buildings is provided by centralized hot water supply system.

2. 1 Selection of heating equipment in public buildings * * * Heating equipment is the core of hot water supply system, and semi-instantaneous steam-water heat exchanger is adopted because of sufficient heat source. It has the advantages of small volume, small floor space, accurate automatic control, floating coil, automatic descaling, automatic supercooling, fast hot water outlet and Legionella prevention.

2.2 BA design of hot water system The BA design of hot water system is mainly to monitor and control the start/stop, failure and hot water temperature of heat exchanger and hot water circulating pump through pressure and temperature signals, and the specific implementation is as follows: (1) display the outlet temperature of heat exchanger and give an over-temperature alarm. (2) Monitoring and fault alarm of hot water circulating pump. (3) The heat exchanger shall make a maintenance list regularly. (4) The hot water circulating pump shall be maintained regularly.

3 quality water supply system

The residential area implements water supply by pipeline, that is, one set of pipe network transports tap water for residents' washing, greening and other miscellaneous purposes, and the other set of pipe network transports high-quality drinking water obtained after advanced treatment of tap water to residents' homes for drinking. If the drinking water standard is 5L/d, the daily drinking water quantity is 1 1.2m3 ... The flow chart of the high-quality water supply system is as follows: tap water → regulating water tank → high-quality drinking water equipment → high-quality drinking water storage tank → variable frequency constant pressure water supply equipment → users → micro-electrolysis sterilizer (pipe network water circulation disinfection) → high-quality drinking water storage tank.

The safety and reliability of fire hydrant and automatic sprinkler system is an important guarantee for residents to live and work in peace and contentment.

In the fire protection design of this residential area, after comparing various schemes and combining with the opinions of the fire department, the fire hydrant and automatic sprinkler system adopt a regional centralized temporary high-pressure fire water supply system, choose a moderate location to set up a centralized fire water pump room, and set up a separate fire water tank for each building, and take measures to avoid the problem of "series pressure" caused by different heights of water tanks. The height of water tank can meet the requirements of hydrostatic pressure in Code for Fire Protection Design of High-rise Civil Buildings. Each individual hydrant is equipped with a button to start the hydrant pump in time in case of fire. The automatic sprinkler system is equipped with a monitoring valve, a water flow indicator and a wet alarm valve. Regional centralized temporary high-pressure fire water supply system has the following advantages:

(1) Save the floor space of residential basement;

(2) Avoid buying fire fighting equipment such as fire hydrant pump, spray pump and electric control cabinet repeatedly, and reduce investment;

(3) It avoids the inconvenience of maintenance and management caused by the scattered setting of fire-fighting pressurization equipment, and is beneficial to the self-inspection of fire-fighting equipment. Because the selected pump flow and lift are considered according to the number of fires in the community at the same time, the pump flow and lift should be determined according to the fire water consumption of the most unfavorable building and the pressure required for the most unfavorable point of the most unfavorable building.

In order to prevent the fire water supply pressure from being too high or the pressure relief orifice plates from being set too much in lower and closer buildings due to different building heights, adjustable pressure relief valves are set at the entrance of fire hydrant and the main pipeline of automatic sprinkler system. The pressure behind the valve does not change with the change of pressure and flow rate before the valve, and the pressure behind the valve is stable when water is supplied. At the same time, DN32 drain valve is set at the back section of the pressure reducing valve to drain water regularly for trial operation.