Common signal system in DCS and SIS system

Abstract

The utility model discloses a common signal system in DCS and SIS system, including DCS server, DCS operation station, DCS system, SIS server, SIS operation station and SIS system, said DCS server, DCS operation station and DCS system are connected with each other and are connected with corresponding control layer I, said SIS server, SIS operation station and SIS system are connected with each other and are connected with corresponding control layer II. According to the method, SIF safety function evaluation is completed in the early stage of design of a project, each interlocking loop has a clear SIL level requirement, a basis is provided for project design according to different SIL level requirements, corresponding interlocking loops are designed, the requirements of DCS control and SIS interlocking are met, meanwhile, the safety requirement of an SIS system is met, and the safety performance of the system is improved. Therefore, the probability of simultaneous failure of the control function and the safety function is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical industry and coal chemical industry, in particular to a common signal system in a DCS and SIS system. Background Art

[0002] At present, most of the control and safety protection of production equipment in the petrochemical and coal chemical industries use BPCS basic process control systems (such as distributed control systems DCS, etc.) and SIS safety instrument systems. In some fields, a process signal needs to be used in both the DCS and SIS systems, and some equipment needs to be shared by the DCS and SIS systems, such as shut-off valves. Both SIS interlocking and DCS sequential control act on the same shut-off valve, which needs to be controlled and interlocked by the DCS and SIS systems respectively. How to handle the relationship between these signals, not only to meet the requirements of DCS control and SIS interlocking, but also to meet the safety requirements of the SIS system, and reduce the probability of simultaneous failure of control functions and safety functions, is a problem that needs to be solved in this field. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the existing defects and provide a common signal system in DCS and SIS systems, provide a basis for engineering design according to different SIL level requirements, design corresponding interlocking circuits, meet the requirements of DCS control and SIS interlocking while also meeting the safety requirements of the SIS system, thereby greatly reducing the probability of simultaneous failure of control functions and safety functions, and can effectively solve the problems in the background technology.

[0004] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a common signal system in a DCS and SIS system, comprising a DCS server, a DCS operating station, a DCS system, a SIS server, a SIS operating station and a SIS system, wherein the DCS server, the DCS operating station and the DCS system are all interconnected and connected to the corresponding control layer I, and the SIS server, the SIS operating station and the SIS system are all interconnected and connected to the corresponding control layer II.

[0005] As a preferred technical solution of the utility model, the I / O channels of the DCS system and the I / O channels of the SIS system are both connected to the MCC system.

[0006] As an optimal technical solution of the utility model, the DCS system is connected with solenoid valve I, solenoid valve II and cut-off valve in sequence, wherein solenoid valve II is also connected to the SIS system, the cut-off valve is connected to the feedback device I and feedback device II respectively, and feedback device I and feedback device II are both connected to the DCS system.

[0007] As a preferred technical solution of the utility model, the DCS system is sequentially connected with a solenoid valve III and a regulating valve, the solenoid valve III is connected to the SIS system, the regulating valve is connected to a feedback device III, and the feedback device III is connected to the DCS system.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: the SIF safety function evaluation is completed in the early stage of the engineering design, and each interlocking circuit has a clear SIL level requirement. According to different SIL level requirements, a basis is provided for engineering design, and corresponding interlocking circuits are designed to meet the requirements of DCS control and SIS interlocking while also meeting the safety requirements of the SIS system, thereby greatly reducing the probability of simultaneous failure of control functions and safety functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the structure of the first embodiment of the utility model;

[0010] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present utility model;

[0011] Figure 3 This is a schematic diagram of the structure of the third embodiment of the present utility model;

[0012] Figure 4 It is a structural schematic diagram commonly used in the prior art.

[0013] In the figure: 1DCS server, 2DCS operation station, 3SIS server, 4SIS operation station, 5control layer I, 6control layer II, 7DCS system, 8SIS system, 9MCC system, 10solenoid valve I, 11solenoid valve II, 12cut-off valve, 13reply device I, 14reply device II, 15solenoid valve III, 16regulating valve, 17reply device III. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0015] The DCS system (distributed control system) is a process control system and is dynamic. It continuously detects, calculates and controls process variables, dynamically controls the production process, ensures product quality and output, and is used for daily production control operations. It requires frequent manual intervention to perform production functions and real-time control.

[0016] The SIS system (Safety Instrument System) is static. Under normal working conditions, it always monitors the operation of the production equipment. The system output remains unchanged and has no impact on the production process. Under abnormal working conditions, it will perform logical operations and interlocking actions according to the pre-designed design to ensure the safety of personnel and production equipment. Generally, human intervention is not required. The SIS system requires strictness and reliability.

[0017] SIS has stricter requirements on reliability and availability than DCS, so the SIS system should be independent of the DCS system and independently complete the safety instrument functions.

[0018] What needs to be emphasized is the principle of independent setting of SIS system: SIL1 logic operator should be separated from DCS, SIL2 logic operator should be separated from DCS, and SIL3 logic operator must be separated from DCS. That is, only when SIL1 and there is no SIL level requirement, and the conditions of relevant national laws and regulations are met, can the control and interlocking functions be considered to be completed in the DCS system.

[0019] Before determining the control plan, it is necessary to confirm that the plan should comply with the requirements of the risk identification or hazard and operability analysis (HAZOP) of the chemical plant, the identification of major hazard sources, the safety instrument function evaluation report, the identification of major hazard sources in the project, and the relevant policy requirements, specification requirements and many national policies and regulations for the two key and one major devices. For example, Order No. 40 of the Safety Supervision Bureau: For the first or second level major hazard sources involving toxic gases, liquefied gases, and highly toxic liquids, an independent safety instrument system (SIS) shall be equipped. In this case, the solution of shared components cannot be adopted.

[0020] DCS and SIS shared components must meet the following requirements: they must comply with all requirements of the entire safety life cycle and must have complete confirmation, verification and records; DCS and SIS shared components will cause a change in the operating mode from a low-demand mode to a continuous mode, and the maintenance procedures and strategies of the relevant components should be changed accordingly.

[0021] In engineering design, it is often encountered that the signals of the same process parameter need to be input to both SIS and DCS at the same time. When the safety level requirement is high, two transmitters are set up respectively, and the source components are set up respectively, and the signals are connected to SIS and DCS respectively. When the safety level requirement is not high and it complies with the regulations of the specifications and relevant national laws and regulations, the traditional practice is usually to set up a transmitter through the attached drawings in the manual Figure 4The signal of a field transmitter is directly hardwired to the SIS system, and the power supply of the transmitter is provided by the SIS. If it is an intrinsically safe circuit, the signal can be distributed to the DCS system through a one-input and two-output safety barrier installed in the SIS system cabinet. If it is a general explosion-proof circuit, the signal can be distributed to the DCS system through a one-input and two-output isolator installed in the SIS system cabinet. The signal transmitted to the DCS is realized by hard-wiring the outlet of the one-input and two-output safety barrier or isolator, and does not involve the I / O card of the SIS system. This signal can be used for DCS signal display, control, interlocking, etc.

[0022] The specification states: "When using a separate SIS sensor, it is beneficial to forward the signal to the DCS through an appropriate isolator", so the transmitter should have safety function requirements and self-diagnosis functions to ensure the reliability and safety of the transmitter and ensure that the SIS system can put the process into a safe state within the required time.

[0023] The signal of a field transmitter is directly hard-wired to the SIS system, and the SIS system connects the signal to the DCS system through communication. This signal is used for DCS signal display and cannot be used for control, interlocking, etc.

[0024] Embodiment 1:

[0025] See also Figure 1 The utility model provides a technical solution: a common signal system in a DCS and SIS system, comprising a DCS server 1, a DCS operation station 2, a DCS system 7, a SIS server 3, a SIS operation station 4 and a SIS system 8, wherein the DCS server 1, the DCS operation station 2 and the DCS system 7 are all connected to each other and to a control layer Ⅰ 5 corresponding thereto, the SIS server 3, the SIS operation station 4 and the SIS system 8 are all connected to each other and to a control layer Ⅱ 6 corresponding thereto, and the I / O channels of the DCS system 7 and the I / O channels of the SIS system 8 are all connected to an MCC system 9.

[0026] When the SIS system interlocks the start and stop action of a pump, the operation station of the DCS system can also manually start and stop the pump. Some solutions are that the DCS transmits the action command to the SIS through communication, and the DCS command is transmitted to the SIS through hard wiring to participate in the logical operation of the SIS system. The specification stipulates: "The basic process control system should not intervene in the operation or logical operation of the safety instrument system", so the DCS and SIS cannot use communication to transmit such action commands, nor can the action command signal be transmitted through hard wiring.

[0027] Therefore, the first embodiment is adopted to solve the problem: if the safety level of the SIS interlocking circuit is ≦SIL 1 or has no SIL level, and meets all the requirements of the application, the entire interlocking logic can be moved to the DCS for completion, otherwise the SIS interlocking logic is still implemented in the SIS, and the start and stop commands of the DCS are directly output to the MCC (motor control center) without being implemented through the SIS. This requires adding a DCS parking contact in the electrical control circuit.

[0028] Embodiment 2:

[0029] See also Figure 2 The utility model also provides a technical solution, which is roughly the same as the first embodiment, except that: the DCS system 7 is connected with a solenoid valve Ⅰ10, a solenoid valve Ⅱ11 and a cut-off valve 12 in sequence, wherein the solenoid valve Ⅱ11 is also connected to the SIS system 8, and the cut-off valve 12 is respectively connected to the feedback device Ⅰ13 and the feedback device Ⅱ14, and the feedback device Ⅰ13 and the feedback device Ⅱ14 are both connected to the DCS system 7.

[0030] When a shut-off valve participates in both SIS interlocking and DCS sequential control, it is also a shared device problem. The specification states: "When a single valve is used for both DCS and SIS functions, the design should ensure that the SIS action is delayed beyond the DCS action. This requirement can generally be achieved by connecting the SIS directly to a solenoid valve that can directly disconnect the actuator power source, such as between the valve positioner and the actuator."

[0031] The second embodiment is used to solve the problem: if the safety level of the interlocking circuit of the SIS and all safety requirements meet the requirements, the entire interlocking logic can be moved to the DCS for completion, so that the interlocking and sequential control are both implemented in the DCS.

[0032] If the safety level requirement of the SIS interlocking circuit is high, two cut-off valves can be used to achieve it, one for SIS interlocking and one for DCS sequential control. This requires additional equipment, so it is preferred to use a cut-off valve 12 and configure two solenoid valves (solenoid valve I 10, solenoid valve II 11), one solenoid valve participates in SIS interlocking and the other solenoid valve participates in DCS sequential control. This method must pass PDF calculation to ensure the safety function requirements.

[0033] Embodiment three:

[0034] See also Figure 3The utility model also provides a technical solution, which is roughly the same as the first and second embodiments, except that: the DCS system 7 is connected with a solenoid valve III15 and a regulating valve 16 in sequence, the solenoid valve III15 is connected to the SIS system 8, the regulating valve 16 is connected to the feedback device III17, the feedback device III17 is connected to the DCS system 7, and a positioner can also be set between the solenoid valve III15 and the DCS system 7.

[0035] When the control valve needs to participate in the regulation on the one hand and the interlocking on the other hand, it is also a problem that the DCS and SIS systems share one device. If the safety level requirement is relatively high, the interlocking cut-off function can be completed by setting up a new cut-off. However, when the safety level requirement is not very high, the solenoid valve Ⅲ15 can also be installed on the gas line of the control valve. The signal of the solenoid valve Ⅲ15 comes from the SIS system. The safety requirement of this setting is lower than that of setting up a cut-off valve independently, and higher than that of realizing regulation and interlocking in the DCS system. The specific requirements should be determined by the requirements of the safety function SIL of the interlocking circuit and the requirements of relevant national laws and regulations.

[0036] Embodiment 4:

[0037] The utility model also provides another technical solution, which is substantially the same as the first, second and third embodiments, except that: the valve position feedback of the shut-off valve is connected to the DCS system, and the valve position feedback signal of the shut-off valve is checked in the DCS. If it is in a safe position, the output of the DCS regulator is also adjusted to a safe position, and the valve position feedback signals of the regulating valve and the shut-off valve are compared, and an alarm is issued when they are inconsistent.

[0038] On one pipeline, there are a DCS regulating valve and a shut-off valve for SIS interlocking. The regulating valve also participates in the SIS interlocking. When the SIS interlocking is triggered, the shut-off valve is actuated and requires the DCS regulating valve to move to a safe position at the same time. The output of the valve positioner of the regulating valve is directed to a safe position, which is not completed by the action of the solenoid valve on the gas path of the regulating valve. The specification stipulates: "The safety instrument system should not intervene in or replace the work of the basic process control system". According to this provision, the SIS system cannot transmit this signal to the DCS. In some foreign process packages, similar situations are transmitted to the DCS by SIS through communication. Therefore, the fourth embodiment is adopted to solve the problem.

[0039] The project completes the SIF safety function evaluation in the early stage of design. Each interlocking circuit has a clear SIL level requirement, which provides a basis for engineering design. However, some projects do not perform safety function evaluation. This requires sufficient communication between automatic control personnel and process personnel to clarify the importance of interlocking and the extent of harm caused by accidents, and preliminarily estimate a SIL level as the basis for interlocking circuit design.

[0040] According to the above analysis, sharing equipment between SIS and DCS systems is a very strict matter and can only be used when all prerequisites are met.

[0041] The undisclosed parts in the present utility model are all prior art, and their specific structures, materials and working principles are not described in detail. Although the embodiments of the present utility model have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present utility model, and the scope of the present utility model is defined by the attached claims and their equivalents.

Claims

1. A common signal system in a DCS and SIS system, characterized in that: The invention comprises a DCS server (1), a DCS operating station (2), a DCS system (7), a SIS server (3), a SIS operating station (4) and a SIS system (8), wherein the DCS server (1), the DCS operating station (2) and the DCS system (7) are all connected to each other and to a corresponding control layer I (5), and the SIS server (3), the SIS operating station (4) and the SIS system (8) are all connected to each other and to a corresponding control layer II (6).

2. A common signal system in a DCS and SIS system according to claim 1, characterized in that: The I / O channels of the DCS system (7) and the I / O channels of the SIS system (8) are both connected to the MCC system (9).

3. A common signal system in a DCS and SIS system according to claim 1, characterized in that: The DCS system (7) is connected in sequence with a solenoid valve I (10), a solenoid valve II (11) and a cut-off valve (12), wherein the solenoid valve II (11) is also connected to the SIS system (8), and the cut-off valve (12) is respectively connected to a feedback device I (13) and a feedback device II (14), and both the feedback device I (13) and the feedback device II (14) are connected to the DCS system (7).

4. A common signal system in a DCS and SIS system according to claim 1, characterized in that: The DCS system (7) is connected in sequence with a solenoid valve III (15) and a regulating valve (16); the solenoid valve III (15) is connected to the SIS system (8); the regulating valve (16) is connected to a feedback device III (17); and the feedback device III (17) is connected to the DCS system (7).

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