1 Water supply system before renovation
According to the actual water consumption record, the water supply system used 335,000 tons of water in the year before the renovation, and the maximum water consumption during the test period was 1,600 tons/day, and the water consumption during non-working hours was 350 tons/day. The water consumption during the untested working hours was 560 tons/day. When the equipment using cooling water runs 1360.5 units throughout the year, the water consumption is 96 tons/set? At the time, there is no recycling. In other words, in the non-working hours, 350 tons / day of water was wasted, 96 tons / Taiwan in the test time? When the water is wasted, it not only causes a huge waste of water resources, but also increases the cost of tap water and sewage, and also puts a lot of pressure on the drainage facilities.
2 Determination of water supply system transformation plan
2.1 In-depth investigation, find out that the waste channel visited the main water users, and on the basis of understanding the water use situation, we conducted continuous monitoring for 48 hours of the discharge of the tester cooling water and the drainage of each plant. It was found that some of the valves were damaged, but they were not replaced. Some valves were not leaking tightly, some valves were not closed, and even the tester cooling water valve was not closed. During the test, the air compressor of No.7 and No.8 was tested for a long time. The temperature of the air bearing bush was soon approaching the upper limit. The required cooling water came from the water tower. The cooling water returned to the collecting tank after cooling the air compressor. The water is mixed with the water from the water tower, and then sent to the air compressor for cooling by the cooling water circulation pump. Another part of the water flows through the overflow pipe to the secondary tank and is pumped to the water tower by the secondary pump. The water supply point of the cooling water system is set in the secondary water tank, and the tap water is used to directly replenish water. The water tower also supplies water to the fire water system and other cooling systems that use relatively little water. In the first transformation, the originally cooled cooling water is returned to the water for recovery, enters the collecting tank 2, and is sent to the secondary water tank by the lifting pump. Due to the flow rate of the pump unit, the water supplied by the water tower is insufficient. When the secondary pump is turned on, the secondary tank may be evacuated, that is, the secondary pump is in danger of cavitation.
The cooling water of No.1~6 air compressor is cooled by the cooling water of No.7 and No.8 air compressors and the mixed water from the cooling tower, and is sent to the No.1~6 air compressor for cooling by the cooling water circulation. It forms a blockage and cannot be recycled. It can only be released.
The return water from the sump to the secondary tank is returned by gravity, and the return flow is limited. When multiple air compressors are simultaneously turned on, the amount of water entering the sump is too large. In order to keep the water level of the sump from being too high, the drainage device is opened for drainage, so that the actual return water is only about half of the theoretical return water, causing cooling. A huge waste of water.
2.2 Formulating the rectification plan First replace the damaged valve, and use the time-delay self-closing valve on the toilet flushing pipe. The cooling water recovery of 105 plant, 111 plant, 104 plant and 311 plant will be considered in the overall return water reconstruction project. Clean the cooling tower, clean the cooling tower packing debris entering the cooling water system, completely replace the original cooling tower packing, and repair the air inlet fence to enable it to operate normally. The cooling water of the air compressors No. 1~6 is recovered, cooled by the cooling tower, and then returned to the sump 1, mixed with the cooling backwater of the No. 7 and No. 8 air compressors, and then sent to the 1~6 by the cooling water pump. The air compressors No. 7, 8 are cooled to reduce the overflow water flow of the pool 1 and solve the problem of slow gravity return and large loss. The water flowing out of the overflow pipe flows back to the secondary water tank reserve under the action of the height difference. The modified cooling water system is shown in Figure 2. Since the cooling water will be quickly contaminated during operation, in order to ensure the cooling effect and prolong the service life of the pump, we have a sewage system under the sump 1 to discharge the suspended solids in the circulating cooling water out of the system in time. The amount of sewage discharged is (1~2)% of the circulating water volume according to the water quality. During the operation of the cooling water, part of the water is discharged with the sewage, and some of the water will evaporate in the cooling tower, so that the circulating water in the system is less and less. In order to ensure the normal operation of the system, the system should be replenished in time. The hydration is carried out using the original hydration system. The amount of water replenishment is (2~4)% of the circulating water volume. In order to prevent unnecessary water loss and cause a new round of waste, we have determined the upper and lower water level lines for the secondary pump water tank, water tower, sump 1 and sump 2 for the operator to supervise the water level. At the same time, for the secondary pump water tank, the water tower is equipped with upper and lower water level start and stop pump interlocking device. Completely eliminate the occurrence of water leakage.
3 After the transformation, the operation and water saving situation
Due to the addition of a cooling tower, the cooling water is sufficiently cooled, the temperature of the cooling water entering the air compressor is further reduced, and the cooling effect of the cooling water on the air compressor is significantly improved. Before the renovation, the cooling water consumption will be 595,641 tons per year if it is not retrofitted and calculated according to the annual operating platform after the transformation. The water consumption after the transformation is actually the sum of the discharge amount of the cooling water and the evaporation amount, which is about 2% of the circulation flow rate of the cooling water. The project has invested a total of 52,000 yuan (including the maintenance cost of the cooling tower). The water saved is calculated at 5 yuan/m3, which can save nearly 3 million yuan per year. It can be seen that the effect of water saving is very significant.
4 Conclusion
1 Some of the early circulating water systems became increasingly unsuitable for production as the nature of production changed and the scale of production expanded. 2 In combination with the actual conditions of the circulating water system and the specific requirements of current production, the system form was improved in time to meet Changing production needs are essential; 3 system retrofit costs can be recovered in a short period of time. 4 The modified system not only can better serve the production, but also reduce the production cost.
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