Because of geological disasters, corrosion defects, third party damage and other factors, there are many hidden dangers in the safe transportation of oil and gas pipelines. Therefore, it is of great practical significance to study the law of leakage and diffusion of buried natural gas pipelines for the prediction and location of leakage points and the formulation of emergency plans.Numerical analysis of the leakage and diffusion process of buried natural gas pipeline is carried out, the influence of leakage velocity, wind speed and environmental temperature on CH4 the methane concentration are analyzed and summed up diffusion law.The research results can provide theoretical support for the accurate location and emergency plan of the buried gas pipeline leakage point.

The high concentration ammonia nitrogen wastewater from Fushun Catalyst Plant was treated by single factor experiment and orthogonal experiment with magnesium ammonium phosphate method. The results were fitted and optimized by penalty function method and Gauss Newton method. The results of orthogonal experiments show that n(Mg)/n(N) has the greatest influence on the removal rate of ammonia nitrogen, followed by pH, while n(P)/n(N) has the least influence. The fitting curve was obtained by Gauss Newton method, and the optimal reaction conditions were determined by penalty function method: n(Mg)/n(N)=1.30,n(P)/n(N)=1.26, pH=9.59. Under the process condition, the removal rate of ammonia nitrogen is 99.79%, and the mass concentration of residual ammonia nitrogen is 28.33 mg/L, which meets the secondary standard of sewage discharge.