1. Process description:
The raw water is well water with high suspended matter content and high hardness. In order to make the incoming water meet the requirements of reverse osmosis incoming water, a mechanical filter equipped with fine quartz sand is installed to remove suspended solids and sediment in the water. and other impurities. Antiscalant adding system can add antiscalant at any time to reduce the tendency of hardness ions in water to scale and prevent concentrated water structure. The precision filter is equipped with a honeycomb-wound filter element with a precision of 5 microns, which further removes hard particles in the water and prevents the membrane surface from being scratched. The reverse osmosis device is the core part of seawater desalination equipment. Single-stage reverse osmosis can remove 98% of salt ions in water, and the second-stage reverse osmosis water meets user requirements.
2. Mechanical filtration operation
Exhaust: Open the upper drain valve and upper water inlet valve, and send the water in the filter to the upper drain valve for continuous water inflow.
Forward flushing: Open the lower drain valve and the upper water inlet valve to allow water to pass through the filter layer from top to bottom. The import flow rate is 10t/h. It will take about 10-20 minutes and the drainage will be clear and transparent.
Operation: Open the water outlet valve and transport water to downstream equipment.
Backwashing: After the equipment has been running for a period of time, a filter cake forms on the surface due to the retention of dirt. When the pressure difference between the inlet and outlet of the filter is greater than 0.05-0.08MPa, backwashing should be performed to ensure smooth water flow. Open the upper drain valve, backwash valve, and bypass valve, and flush with a flow rate of 10t/h for about 20-30 minutes until the water is clear. Note: After backwashing, the equipment must be forward washed before it can be put into operation.
3. Softener switching and cleaning.
The working principle of the softener is ion exchange. The characteristic of the ion exchanger is that the resin needs to be regenerated frequently. Please pay attention to the following issues when using:
When the hardness of the effluent water exceeds the standard (hardness requirement ≤0.03mmol/L), the machine must be shut down for regeneration; the cationic resin regeneration method is to soak the resin in salt water for about two hours, let the salt water dry, and then use it. After flushing with clean water, you can continue to use it;
4. Add an anti-scaling system and the metering pump and the high-pressure pump start and stop at the same time and run synchronously.
The antiscalant is MDC150 produced in the United States. Dosage of antiscalant: According to the hardness of the raw water, the dosage of antiscalant per ton of raw water is 3-4 grams. The water intake of the system is 10t/h, and the water consumption per hour is 30-40 grams. Preparation of antiscalant: Add 90 liters of water to the chemical tank, then slowly add 10 kg of antiscalant and stir evenly. Adjust the metering pump range to the corresponding scale. Note: The minimum concentration of antiscalant should not be less than 10%.
5. Precision filter
The filtration accuracy of the precision filter is 5μm. In order to maintain filtration accuracy, the system does not have backwash pipes. The filter element in a precision filter generally has a service life of 2-3 months, which can be extended to 5-6 months depending on the actual water treatment volume. Sometimes in order to maintain water flux, the filter element can be replaced in advance.
6. Reverse osmosis cleaning
Due to the long-term accumulation of impurities in the water, the reverse osmosis membrane element is prone to scaling, resulting in a reduction in water production and a decrease in desalination rate. At this time, chemical cleaning of the membrane elements is required.
When the equipment has one of the following conditions, it must be cleaned:
Under normal pressure, the produced water flow rate drops to 10-15% of the normal value.
1. In order to maintain normal produced water flow, the water supply pressure after temperature correction increases by 10-15%;
2. Product water quality decreases by 10-15%;
3. Salt permeability increases by 10-15%;
4. Working pressure increases by 10 -15%.
5. The pressure difference between RO sections increases significantly.