Sedimentation tank is one of the most important facilities in wastewater treatment engineering, and cracks and leakage problems often occur during the construction or use of sedimentation tank due to its huge plane size. The key to the design and construction of twelve 66-meter-diameter sedimentation tanks in a sewage plant was to solve the problems of cracks, soil liquefaction and soil bearing capacity. Compensation concrete and pre-stressed tendons were used respectively to eliminate or avoid the hydration heat temperature difference, shrinkage thermal stress and environmental thermal stress, so as to prevent shrinkage cracks and structure cracks. The liquefaction and bearing capacity problems of foundation soil were solved by using large diameter vibro-replacement stone column. After years of operation, the structure of sedimentation tank is still solid, proving its good application results

This paper discusses the mathematical and mechanical models for the creep of metal materials and their application under high temperature conditions in the engineering design of petrochemical plants, gives the creep curves of materials, studies the Maxwell model, Kelvin model and Maxwell-kelvin model, and presents the stress analysis methods and evaluation standards for high temperature creep pipelines

Elevated flare system is an important safety facility in petrochemical industry. This paper introduces the engineering design example of a new elevated flare in a refinery of Sinopec, discusses the process design and process calculation of the flare system, the major equipment on flare stack and the ignition system, introduces in detail the calculation and selection of the diameter of flare head and the calculation of flare scrubber, water seal tank and flare stack, and provides some ideas and methods for the design and calculation of elevated flare system

Recycling the blowdown from circulating cooling water can not only save the fresh water resource, but also reduce the wastewater discharge. Combined with the engineering example of the recycling of blowdown from circulating water in a petrochemical enterprise, this paper introduces the combined process of pretreatment, ultrafiltration and reverse osmosis for the recycling of blowdown from circulating water, discusses the selection of major processing equipment and the operating parameters, gives the operating cost and benefit evaluation of the recycling project, and analyzes the main factors influencing the water treatment effect, providing reference for the engineering design of similar wastewater recycling projects

This article analyzes in detail the equal area reinforcement calculation methods stipulated in GB 50251, GB 50253 and GB 50316 for extruded tees, and compares the similarities and differences among the calculation formulas in the three standards. Taking X80 steel DN1200×DN1200×DN1000 and DN1200×DN1200×DN900 tees for example, this article performs strength calculation under a design pressure of 12MPa and a regional grade coefficient of 0.5. The results show that the reinforcement area required calculated by GB 50316 is greater than that calculated by GB 50251 and GB 50253, and the reinforcement area available calculated by GB 50316 is less than that calculated by GB 50251 and GB 50253

This paper discusses the problems in the design, selection and operation of balanced bellows pressure relief valves in hazardous environment, and clarifies how to correctly handle the vent on the valve cover of balanced bellows pressure relief valve in view of its particularities in process design and guarantee the correctness of design, selection and hazardous area classification, so as to eventually eliminate the potential risks and ensure the safety and reliability of balanced bellows pressure relief valves

GOST standards are the standards followed by the former Soviet Union. In this paper, a RFCC unit located in Kazakhstan is taken for an example to systematically illustrate the calculation of safety valves with gaseous media in accordance with GOST 12.2.085-2002 Pressure Vessel, Safety Valve Technical Requirements. The results are compared with those of API STD 520. It is shown that, for gaseous media, the required relief orifice areas of the safety valves calculated by the two standards differ not too much, and the selection results are basically the same. In addition, for flammable and explosive medium, hazardous substances of Class 1 and 2 specified by GOST 12.1.007 and low temperature medium, the safety valve should be equipped with mechanical interlock system

In order to reduce the construction cost of oilfield projects in the African market, a scheme is proposed to guarantee the safe operation of the inlet and outlet lines in pigging stations without anchor block. This paper takes a project in Chad as an example, establishes a model for stress analysis by CAESAR II software with the overall consideration of the ASME design standards and the external forces of piping system. The design scheme is optimized by comparing and analyzing the traditional anchor block installation method, the flexible installation method and the flexible installation method with foundation bolts. The model analysis of flexible installation method with foundation bolts is more accurate. Elbows with large radius of curvature on the inlet and outlet lines in pigging stations are set up using the method without anchor block to absorb most of the thermal expansion stress of buried piping, reduce the horizontal thrust on the pig launcher, reduce the investment and ensure the safe operation of the pipelines

Combined with the engineering design example of an isononyl alcohol project newly built on RAPID, Malaysia, this article introduces the key points in the piping design of overseas petrochemical project, and discusses the different requirements of the standards, codes and technical specifications of the owner for the project, the special requirements of overseas owner on unit, equipment and piping layout, stress analysis and material design, and the importance of effective communication with overseas owner

The heat loss of steam pipelines in petrochemical enterprises is tremendous. Five experiment schemes with different thermal insulation structures were proposed based on the selection of thermal insulation material and structure and the calculation of economic thermal insulation thickness. The industrial experiment was carried out on the medium pressure steam pipeline in a branch of Sinopec. The results showed that the economic thermal insulation thickness, double-layer thermal insulation structure and composite thermal insulation structure can reduce the heat loss compared to the former insulation structure. The aerogel blankets can effectively reduce the thickness of insulation layer and improve the efficiency of pipeline arrangement. This research provides guidance for the thermal insulation of steam pipelines in petrochemical industry

Molecular sieve dehydration process is used for the natural gas treatment in Yakela gas station, and differential pressure regeneration and automatic switching of time sequence control are adopted. The serious pulverization and agglomeration of molecular sieve results in high differential pressure of dust filter and cold box and affects the yield of light hydrocarbons. In order to minimize the pulverization and agglomeration of molecular sieve, ensure the dehydration effect of molecular sieve and provide safeguard for the cryogenic hydrocarbon removal of expander-compressor unit, various influential factors such as the molecular sieve dehydration process, the properties of regenerated gas and raw gas, the influence of mercury and the internal structure of molecular sieve drying tower are analyzed to solve the pulverization and agglomeration problem of molecular sieve, and some corresponding countermeasures are put forward based on the actual situations, thus minimizing the pulverization and agglomeration of molecular sieve, improving the dehydration effect of molecular sieve and providing safeguard for cryogenic hydrocarbon removal

This paper studies the application of Aspen Flare System Analyzer in the design of flare net for synthetic ammonia units in natural gas chemical industry. The technical terms related to the design of flare net for chemical plants are introduced, the calculation method, modeling design principle and application scope of Aspen Flare System Analyzer are discussed, and the design of a flare system in an ammonia unit is analyzed. The results show that a diameter of piping should be given by experience before using the Aspen Flare System Analyzer, and choosing the rating mode would obtain a more reasonable size of the flare net and improve the design efficiency of flare net

This article introduces the definition of NPSHa and its significance in the actual operation of centrifugal pumps, analyzes the effect of Venturi jet on the NPSHa of centrifugal pumps through theoretical calculation, and takes a project case as an example to further show that Venturi jet has advantages in improving the NPSHa of centrifugal pumps due to its simple structure, low modification cost and stable operation under certain conditions

The vent gas from propane refrigeration system of light ends recovery unit was designed to be burned via the flare system, resulting in serious waste of resources and environmental pollution. The causes of the venting of the vent gas from propane refrigeration system are analyzed, and a process scheme for separately recycling the gas-phase propane and liquid-phase propane from the vent gas is proposed, so as to successfully achieve the recovery of vent gas from propane refrigeration system, save resources and reduce environmental pollution

Exchanger tube rupture is a remote but possible contingency. It is difficult for calculating the relief flowrate, especially for vapor-liquid phase. This article analyzed the formula of this case and describes the calculation method of exchanger tube rupture case relief flowrate base on literature search and engineering experience

This paper introduces the problems in the operation of floating ring seal of recycle gas compressor in the linear low density polyethylene unit at SINOPEC Guangzhou Company, and analyzes the reasons for the frequent failures of floating ring seal from the aspects of structure, failure phenomenon and sealing principle. In view of the successful application of dry gas seal technology in centrifugal compressors, the measures for replacing the floating ring seal of compressor rotors with dry gas seal were determined. The rotor shaft seal has been continuously and stably operated for two overhaul cycles after the modification, and the operation results show that the dry gas seal of rotors has good effect

Through the analysis of the problems in an imported electro-hydraulic actuator for the inlet butterfly valve of flue gas turbine expander, a technical scheme of high reliability electro-hydraulic actuator was put forward, and the high reliability electro-hydraulic actuator was successfully developed based on the theories and methods of hydraulic drive, automatic control and reliability technology. Its technical performance, economic efficiency and safe production were comprehensively evaluated, and its efficiency was compared with that of similar products abroad

Continuous liquid-phase diesel hydrotreating process requires no recycle hydrogen system, so its investment and energy consumption are lower compared to those of traditional trickle bed technologies. On this basis, the second-generation hydrotreating technology integrates the hot high pressure separator into the upflow reactor, further reducing the floor area and investment. It has significant technical and economic advantages. The process simulation proves that the solubility of hydrogen is proportional to the pressure, temperature and hydrogen purity. Higher pressure, temperature and hydrogen purity leads to higher solubility of hydrogen, which promotes the hydrotreating reaction