Operational Characteristic And Improvement Study On Rectification Column For Ammonia Waste Water

Base on a chemical plant, there are too much high concentration ammonia content wastewater in the process, so follow up the requirement of laws, the basis of the original equipmentand the original process by using chemical simulation software for the steamed ammoniatower equipment to improve the analysis of the enterprise, through the simulation analysis,improved the results of the analysis. Simulation results show that the improved measures arefeasible, the ammonia content of wastewater to reduce to a domestic standard regulationswithin the limit of, is to be able to spread in the whole enterprise to use.After7months modify, the new column had been set up, and it has been running in agood condition. This is a good sample for reduce ammonia waste water in chemical plant.The dissertation focus on malfunction elimination and optimization research of theammonia distillation column of a chemic plant (industry ammonia waste water treatment).The production process in this chemical plant could generate about1200~1500kg/hammonia waste water (4~5%)，and the ammonia waste water will has to follow the dischargelimit (<500ppm) after distillated with ammonia. Fifteen year ago, there was a small facility ofammonia column system when this plant had been founded, it could treat the ammonia wastewater for production at that time, and the light component of refined ammonia (25~32%)which come from the top of the column could be recycle used as raw material in this plant. So,we could get benefit from decreasing discharge, protect environment, as well as declineproduction cost numerously.Though in recent years, the ammonia waste water reached to1500~2000kg/h due to thebig capacity increasing, because of the undulation of ammonia waste water components,equipment getting aged and etc, the stripping column usually got un-stability and floodingproblems, treatment capacity could not fulfill process demand. The most important issue wasthe ammonia stripped ratio still on a low level, ammonia concentration in discharging waterwas over800ppm (standard was500ppm), it cause some problems to downstreambiochemistry section, the biochemistry system had ever been collapsed by high concentrationammonia waste water crushing, so this plant had to pause production and decrease thecapacity for improvement for many times. Same time the engineering guys had changed thefilling material, cleaned heat exchanger and increased the power of the re-boiler for manytimes, but it still didn’t helpful. In order to solve these problems totally, technical people had done some researches on domestic and foreign process of ammonia distillation column andcomparing, they found the root cause of the flooding issue. Base on the original equipmentand process, technical people used chemical simulation software Aspen Plus for the ammoniastripping column tower system for simulation running analysis, and then advise improvementsuggestions and actions according to the results. So they enlarged the body of the towerdimension from Φ300to Φ600,added the filling material25#Pall ring to4.25m height,increased the re-boiler power from80KW to160KW,increased the loading power ofcondenser from90KW to200KW.According to the simulation results, this plant implemented this improved measure, after7months modification, the new ammonia distillation column had been set up, it started to beused on Jul.2013,it was running in a good condition after commissioning and testing duringtwo months, the max treatment capacity went to2200kg/h, ammonia concentration indischarging water was below420ppm (standard was500ppm), refined ammonia from the topof tower over30%(25~32%)，the refined ammonia was250kg/h, steam flow speed was1200kg/h, so it meet the original design.The smooth running of equipment proved that this modification was feasible, couldreduce the industry ammonia concentration of waste water to below target and achieve to thedischarge standard of biochemistry of plant. It eliminated the malfunctions of equipmentflooding and low ammonia stripped ratio, optimized the operation circumstance of plant,reduced cost, increased benefit, fulfilled domestic standard regulations within the limit, thiswas able to spread out to other enterprises for using.