Table of Content

20 July 2022, Volume 58 Issue 4

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Process and Technology

Discussion on interlocking shutdown level setting of natural gas purification plant

2022, 58(4):  0-0. 

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Application of CCC unit control system in ethylene refrigeration compressor

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The original control system of the ethylene refrigeration compressor of an ethylene unit adopts the ITCC control system of TRICONEX Company. Since it was put into operation in 2013, the four return two anti-surge valve still has 36% open degree in the semi-automatic condition, and the safety margin of the compressor working point can only be controlled at 3%.In order to ensure the safe operation of the unit, the four-return two anti-surge valve cannot be completely closed, and the anti-surge control controller cannot be fully automatic, resulting in high energy consumption of the compressor.In 2020, the ethylene unit updated the ethylene refrigeration compressor due to energy expansion and transformation, and the American compressor control company (CCC) redundant Prodigy control system realized anti-surge control, stone wall control, steam turbine speed control, steam extraction control and compressor inlet pressure performance control. The original ITCC system retains safety interlocking protection and automatic control of auxiliary units.Through the modification of the control system, the related problems were successfully solved.

Predictive control for pH neutralization process based on multi-model fusion

2022, 58(4):  0-0. 

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As a typical nonlinear system in the field of complex industry, the pH neutralization process has many features such as large delay, strong interference and time variation. It is difficult to satisfy control demands using predictive control based on a single model when the operating condition changes widely. To overcome this difficulty, a predictive control method based on multi-model fusion is presented in this paper. Firstly, the identified models under several typical conditions are fused to make a prediction of the unidentified object model under a new condition. Secondly, the inverse models achieved by identified models are fused again to change the nonlinear process control problem into a linear process control problem. Finally, a predictive controller is easily designed using the dynamic matrix control algorithm to solve the linear problem. The simulation results show that this proposed method has better control performance than the single model predictive control.

Exploration and practice of preventive maintenance strategy of instrument control system in large refining and chemical enterprises

2022, 58(4):  0-0. 

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With the increasing demand of large refining and chemical enterprises to improve the overall reliability of the control system, it is very important to do a targeted and efficient preventive maintenance of the control system. This paper combines the industry standards with the relevant requirements of Sinopec equipment integrity management system. Regarding to the contents not specifically required in the above specifications, a series of independent and innovative preventive maintenance work implemented in the online monitoring, overhaul, new construction and transformation projects of the control system under the framework of the standard specifications are elaborated based on a case of extra-large refining and chemical enterprise by summarizing the maintenance experience over the years and combined with the actual situation. It not only effectively improves the overall reliability of the control system but also reduces the risk in steady production, which providing excellent experience for the same type of refining and chemical enterprises to formulate the preventive maintenance strategy of the control system.

Tuning and Optimization of PID parameters of integral objects based on lambda method

2022, 58(4):  0-0. 

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PID controllers have been running more than 5 billion loops since their inception, and as one of the most widely used and accepted control methods, the overall gain, integral time, and derivative time tuning are the keys to the proper operation of the controller. This article introduces a simple, efficient, and reliable PID parameter tuning method, which is particularly effective for integrating objects. This paper elaborates on the physical significance, derivation process and parameter tuning process of each parameter, and finally uses lambda tuning method to adjust a set of parameters, and brings it back to the original control model for verification, which can obtain excellent loop performance.

Development and Commentary

Digital Twin Applications in Petroleum and Petrochemical Industry: An Overview

2022, 58(4):  0-0. 

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As a bridge connecting the physical and digital space, digital twin (DT) play an increasingly critical role in many fields, promoting the high-quality development of related industries. Recently, the petroleum and petrochemical industry is actively conducting digital transformation, so it is necessary to have an overview of the DT applications. This paper introduces the concept, development and application fields of DT, and comprehensively sorts out its state-of-art applications in the petroleum and petrochemical industry. With the latest theoretical and practical progresses, the DT system architecture and technology framework for petroleum and petrochemical industry are proposed with the potential application scenarios; Finally, the challenges and development trends are summarized.

Innovation and Practice

Comprehensive judgement and treatment of frequent faults of one thermowell

2022, 58(4):  0-0. 

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Hackled the troubleshooting process of frequent faults of one thermowell, after the comprehensive judgment, analysis, calculation, and comparison,gave the ideas and methods in thoroughly solving the typical faults.

Development and application of sequential control logic of Sulphur making furnace in Sulfur-making Unit

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Some issues about sharing sensors between DCS and SIS

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Abstraction: For the purpose of dividing safety instrument system (SIS) and distribution control system (DCS) into two completely separately Independent protective layer (IPL). It is widely forbade for DCS and SIS to share same sensors, which increase project cost apparently. This paper analyzed the issue of IPL number of DCS firstly and proposed that DCS can provide only one IPL. Then, this paper suggest that one SIL2 SIF loop could replace the function of one DCS loop combined with one SIL1 SIF loop. At last, this paper verify the SIL grades of some brand sensors, signal splitters, SIS systems and solenoid valves from PFDavg calculation, systematic capability and architectural constraint. And approved that non-redundant sensor, signal splitter and solenoid valve could build SIL2 loop easily. The conclusion is: for the SIL1 loop in LOPA, SIL grade could be uplifted to SIL2, and use SIS signal splitter to transfer signal to DCS for indicating, alarming, controlling and interlocking. And it is not necessary to design separated sensors for DCS and SIS.

Application and improvement measures of PDS valve in LLDPE unit of Sino-Korea Petrochemical

2022, 58(4):  0-0. 

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PDS high frequency ball valve is the key equipment in polyolefin plant. The failure of valve will lead to load reduction production or even unplanned shutdown of the plant. PDS valve is an important guarantee for the smooth operation of polyolefin plant. Due to the special and complex working conditions, the valve operates in a gas-solid two-phase environment such as polyethylene, polypropylene powder, nitrogen, hydrogen and hydrocarbon substances, and at the same time requires fast valve switching time and high operation frequency, resulting in a high valve failure rate. According to the common faults in the daily operation of PDS valve, reasonable transformation schemes are put forward to reduce the failure rate of valve and ensure the long-term normal operation of valve, which is an important guarantee for the safe and stable production of polyolefin unit.

Safety and Environment Protection

SIL Level verification of oil and gas station based on human factor reliability analysis

2022, 58(4):  0-0. 

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Engineering Design and Standards

SIL checking calculation and sensitivity analysis of coal gasification

2022, 58(4):  0-0. 

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