Assessment On Implementation Of Pollutants Emission Standard And Analysis Of Environmental Risk For Nitric Acid Industry

The nitric acid industry is an important part of the chemical industry and plays an important role in the development of the national economy.Through the development in recent decades,the scale of China’s nitric acid industry has grown stronger.Especially with the increasing demand for nitric acid in recent years and the shift of nitric acid industry policies in developed countries,it has greatly promoted the rapid development of China’s nitric acid industry.At the same time,due to the constraints of the coordinated management of laws and regulations on environmental protection in the industry,the emissions of pollutants have also been effectively controlled,and the emissions have been declining year by year,and significant reductions have been achieved.In order to fully implement the spirit of the 19th CPC National Congress and the Third Plenary Session of the 19th CPC Central Committee,and firmly establish the development concepts of innovation,coordination,greenness,openness and sharing,the“Thirteenth Five-Year Plan for Development of National environmental Protection Standards”clearly proposes to focus on environmental quality standards and pollutant discharge standards,and comprehensively accelerate the development and revision of various environmental protection standards to build a lean and efficient environmental protection system.The management of pollutant emission standards in China has also begun to shift from focusing on standard revision to a stage of standard revision,implementation evaluation,publicity and training.The"Emission Standards of Pollutants for Nitric Acid Industry"（GB 26131-2010）has been implemented for ten years,and there are also certain environmental risks in the nitric acid industry itself.Therefore,on the basis of comprehensively coordinating the positive factors such as other national environmental protection laws,regulations,pollution permit systems,and environmental impact assessment systems,and fully coordinating the relationship between environmental protection and economic development,it is not only of great significance to evaluate the implementation of the"Emission Standards of Pollutants for Nitric Acid Industry"（GB 26131-2010）,and to analyze the nitric acid industrial air pollutant emission reduction potential and corresponding environmental risks according to the characteristics of the industry,but also can provide support for the upcoming revision work.This article is based on the literatures and on-site investigations of enterprises,to understand the general situation of the nitric acid industry,and to grasp the status of domestic and foreign industry development,production processes,pollutant control technologies,and possible environmental impacts.It has also sorted out the pollutant emission standards that have been implemented in the industry in the past,and related foreign pollutant emission standards,and then compared and analyzed the two to explore the advanced and scientific nature of the current standards.According to the"Guidelines for Implementation Evaluation of National Pollutant Discharge Standards（Trial）",the implementation of the"Emission Standards of Pollutants for Nitric Acid Industry"（GB 26131-2010）was evaluated,mainly including the standard compliance rate analysis,economic and technological benefits analysis,environmental benefits analysis,social benefits analysis and NO_X emission reduction potential analysis.At the same time,according to the current situation of the surveyed enterprises,the analysis of the environmental risk sources and the prevention measures for environmental risks were proposed.The specific content and results are as follows:（1）The applicable scope and pollution factors of GB26131-2010 were analyzed,and relevant suggestions were made.Compared with previous standards,this standard is innovative for the first time to add a special emission limit;and compared with relevant foreign standards,the emission limits of this standard are at a relatively advanced level.It is suggested that in the future revision of this standard,the scope of application should be appropriately extended to enterprises using nitric acid as raw material,and N₂O,ammonia and nitric acid mist should be included in the restrictions.（2）Evaluation and analysis of GB26131-2010 found that the standard has achieved good results in all aspects since its implementation.At present,all companies in the industry have achieved a pollution discharge rate of almost 100%.From a technical perspective,the ammonia oxidation process and advanced SCR end treatment technology have been widely used;Economically,the cost of production and operation and equipment replacement is also within the company’s affordability.At the same time,the reduction in the cost of sewage charges can also bring certain economic benefits to the company;In terms of environment,the emission of NO_X has been greatly reduced after the implementation of this standard,and good environmental benefits have been obtained.Compared with the restriction of the old standard,the COD emission reduction of the nitric acid industry in 2018 was about 2million tons,and the reduction of NO_X was about 30000 tons under the restriction of the new standard.（3）In this paper,an LMDI model based on exponential decomposition analysis was used to analyze the emission reduction potential of nitric acid in the nitric acid industry.The four main factors affecting NO_X emissions were explored:technical effects,governance effects,structural effects,and economic effects.Among them,the technological and governance effects are the main factors to promote emission reductions,structural effects have less impact,and economic benefits will promote NO_X emissions.As of 2018,both technical and governance effects had reduced NO_X emissions by nearly 12,000 tons.At present,the NO_X emission concentration of most enterprises is far below the standard limit,and most of them are basically around 100 mg/m³,indicating that the industry still has a certain potential for emission reduction.（4）According to the"Guidelines for Enterprise Environmental Risk Assessment（Trial）"and"Risk Classification Method for Environmental Emergencies of Enterprises"（HJ 941-2018）,the risk substances that may exist during the production and storage of the nitric acid industry and the possible hidden danger that may occur were identified,especially to avoid major accidents such as leakage and even fire.Taking a nitric acid company in Shanxi as an example,according to the"Risk Classification Method for Environmental Emergencies of Enterprises"（HJ 941-2018）,environmental risk identification,environmental risk classification,and environmental risk analysis were carried out,and related prevention and control measures were proposed to reduce the risk,and the risk was reduced to an acceptable level for the enterprises.