| The regeneration waste water of power plant condensate polishing system has the character of high salt content, high ammonia, low scaling ion. At present, the conventional disposal methods of the regeneration waste water of power plant are that acidic waste water enter into the ash system as replenishment, alkaline waste water is used as desulfurizer, or acidic and alkaline waste water are mixed, neutralized and reach discharge standard. With the national environmental protection laws and regulations becoming stricter, more and more power plants began to develop in the direction of zero discharge of waste water, how to deal with the recovery of The regeneration waste water of power plant condensate polishing system containing high slat and high ammonia is badly in need of solving technical problems in power plant.Based on the characteristics of the regeneration waste water of power plant condensate polishing system, in this article, using two stage reverse osmosis technology reclaimed the chemical resources such as sodium chloride and ammonia in the regeneration waste water of power plant condensate polishing system, the experiment of one-level RO studied the effects of RO element, raw water pH and RO recovery ratio on the operation pressure, desalt ratio and ammonia penetration ratio. The operation stabilization under extreme condition was also studied and the fouling elements on membrane surface were analyzed. Using the water production of one-level RO as the inflow of second-level RO and controlled 86% by the recovery ratio of system, the experiment of second-level RO simulated operation performance of system in the condition of different membrane flux.The experiment results of one-level RO show that:(1)Under the same experiment conditions, the operating pressure of DOW and HYD RO element were basically identical, but desalt ratio of DOW RO element was about 1.0%~1.2% higher than HYD RO element.(2)When the system recovery ratio was controlled 65%, the membrane desalt ratio and ammonia penetration ratio were increased with the rise of raw water pH. The membrane desalt ratio and ammonia penetration ratio were relative to the highest when pH of the raw water was 10.(3)When pH of the raw water was 10,the penetration mass of salt and ammonia of RO process is in direct proportion to the system recovery ratio. When the recovery ratio was from 15% to 75%, the penetration mass of salt of water production was from 288mg/L to 1970mg/L, the penetration mass of ammonia of water production from 1250mg/L to 2460mg/L.(4)Under the condition that pH of the raw water was 10, the recovery ratio was 75% and the membrane flux constant, the operation pressure was 8.5 MPa, the recovery ratio of RO was 75%, the TDS and ammonia of product water was 1970 mg/L and 2460 mg/L separately, the membrane desalt ratio was between 95.5% and 95.9%, and the experimental equipment was operated stably.The qualitative and quantitative analysis on the fouling material and the surface morphology of one-level RO membrane tested.The membrane analysis results showed that there was lots of fouling material with looseness of structure sticking on the membrane surface, and the main fouling material was ferric dioxide with small amount of chemical compounds of silicon and manganese by means of chemical composition analysis. So, during the system design, using appropriate pre-treatment technology removed ferric dioxide in order to meet RO membrane water quality and operation safety requirements.The experiment results of second-level RO show that:When the membrane flux of RO system was controlled 26.7L/m2·h, the penetration mass of salt of water production 476mg/L, the membrane desalt ratio was 96.00%, the penetration ratio of ammonia 73.23%; When the membrane flux of RO system was controlled 37.5L/m2·h, the penetration mass of salt of water production 360mg/L, the membrane desalt ratio was 96.95%, the penetration ratio of ammonia 77.38%. The results indicated that the desalt ratio and penetration ratio of ammonia was relative higher when the membrane flux of RO system was controlled 37.5L/m2·h. |
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