Definition
The safety system is an organic whole with specific functions combined with several factors related to production safety issues that are related to each other, interacts, and restricts each other.
In industrial enterprises, human-machine systems, safety technology, occupational health and safety management constitute a safety system. In addition to the characteristics of a general system, it also has its own structural characteristics. First, it is a human-centered human-machine matching system with feedback process. Therefore, the coordination between humans and machines should be fully considered in the system security mode. Second, the security system is a combination of engineering and social systems. The person at the center of the system must be affected by society, politics, culture, economy, technology, and family. The above factors must be considered, so that the system's security control can be more effective. Third, the occurrence of safety accidents (the unsafe state of the system) is random. Firstly, it is uncertain whether the accident occurs or not; secondly, it is impossible to know exactly what kind of consequences the accident will cause in advance. Fourth, the ambiguity of accident identification. There are some factors that cannot be quantitatively described in the security system, so the description of the security state of the system cannot be clearly quantified. Safety system engineering activities should be based on the above characteristics to carry out research work and seek effective methods to deal with safety issues.
Design principles
Industrial safety systems mainly include signal alarms and safety instrument systems, which are one of the important measures to ensure safe production. Most chemical processes require signal alarms and safety instrumented systems to adopt the principle of fail-safety, so that the equipment will enter a predefined safe state when a specific fault occurs. In addition, instruments and equipment in industrial production installations often have requirements for anti-corrosion, dust-proof, shock-proof, anti-electromagnetic interference, and explosion-proof. The design principles of the safety system are as follows:
(1) The setting of signal alarm, interlocking point, action setting value and adjustment range must meet the requirements of the production process;
(2) On the premise of meeting safety in production, we should try our best to choose a solution with simple circuits and a small number of components;
(3) Safety-related systems should be installed with low vibration, less dust, no corrosive gas, and no electromagnetic interference
(4) When applying DCS and PLC, DCS/PLC certified by an authority can be used to construct safety-related systems;
(5) Install in safety-related systems The detection devices, actuators, buttons, signal lights, switches, etc. in hazardous locations shall meet the requirements of explosion-proof and fire-proof of the location;
(6) The power supply requirements of safety-related systems are the same as those of general instruments. To ensure the stable and reliable operation of important safety instrument systems, they should be equipped with uninterrupted power supplies.
Design steps
The safety system design steps are as follows:
The first step: Define the risk level
Introduce safety protection in the production equipment Means, its role is to reduce the risk to a level acceptable to the enterprise. No protection means can completely eliminate the risk.
Due to the complexity of petrochemical production equipment, the number of potential risks is extremely large, and it is impossible to take measures against all risks. Therefore, it is necessary to clearly define how much risk is acceptable before designing a safety-related system, and what kind of risk must be taken. Only after the risk level is clearly defined and divided, can we use this as a measurement indicator to find the key risks that must be resolved among the many potential risks.
Step 2: Identify all potential risks
After defining the risk level, use a reasonable safety evaluation method to fully and thoroughly identify the possible risks in the device, and obtain the device The dual relationship between the cause and the consequence of each risk. Only on the basis of obtaining all possible potential risks, can the device be fully and completely designed and checked for the protective layer.
Step 3: Check the design of the protective layer
For each possible risk identified in the second step, consider the degree to which the existing protection measures reduce the risk , Check whether it meets the acceptable range defined in the risk matrix. If the requirements cannot be met, new protective measures need to be introduced, and the degree of risk reduction after the introduction of new protective measures is recalculated.
Step 4: Conclusion review
Check whether all unacceptable risks have been protected, that is, all risks have reached the "acceptable" range. If not, go back to the third step to recheck and design the protective layer.
Engineering description
Safety system engineering in a narrow sense, the main focus is on economic system safety, especially production safety in economic systems. General safety system engineering textbooks are mostly safety in a narrow sense System engineering category. The basic framework of security system engineering based on the comprehensive integration method. Broadly speaking, security system engineering belongs to the category of Social System Engineering (SSE), involving any social subject's double-layer goal of "Security and Development (S&D)" Architecture, covering all security fields of any social subject, such as: economic security (material civilization), cultural security (spiritual civilization), political security (political civilization, including military), environmental security (ecological civilization), human-oriented security (human This article specifies) and so on.
System safety engineering is an emerging engineering discipline that developed rapidly in the 1960s. It is an engineering technology that researches and solves safety problems in the production process by means of systems engineering.
System security engineering is used to identify, analyze, and eliminate the potential hazards of the system, and reduce the risk of the system to an acceptable level. It has shown great effects in ensuring industrial production and product safety.
In foreign countries, system safety engineering has been widely used and has become a safety technology that must be used in industrial production. In China, with my country's entry into the WTO, system safety engineering has received great attention, and the education, research and engineering practice of system safety engineering have made considerable progress. As a safety engineer engaged in safety technology or management work in the new century, he must have knowledge of system safety engineering and master the analysis methods of system safety engineering. The "System Safety Engineering" course is the disciplinary foundation of the safety engineering major, which is also an important knowledge component of other engineering majors.