First, the LNG center control room explosion-proof design necessity
Throughout the domestic LNG plant facilities, the current new device center control room is generally arranged outside the device area (whether the need for explosion-proof should be based on the results of the explosion risk assessment to determine); and the construction of small-scale LNG plant projects in previous years, there are a large number of plants in the plant center control room was built within the device area as a whole important facilities and personnel Concentration of places, and its relatively close to the fire hazard equipment, according to "special rectification of hazardous chemical safety three-year action to implement the program" of the provisions of the requirements of this type of device in the central control room anti-explosive design and construction of rectification will inevitably face the subject. Specifically, the implementation of the program on the anti-explosive control room rectification requirements are as follows:
(1) involves the production of explosive hazardous chemicals control room, shift room shall not be arranged in the device area, has been built and put into use must be completed before the end of 2020 rectification.
(2) involving Class A and B fire hazards of the production plant control room, the shift room in principle shall not be arranged in the device area, do need to be arranged in accordance with the "Petrochemical Control Room Explosion Resistant Design Specification" (GB50779-2012), before the end of 2020 to complete the anti-explosive design, construction and reinforcement.
(3) with a class A and B fire hazards, dust explosion hazards, poisoning hazards of the plant (including devices or workshops) and warehouses within the office, rest rooms, outside the operating room, inspection room, August 2020 before they must be dismantled.
Against the above provisions (2), the central control room in the LNG plant should refer to GB50779 (note that the specification is currently being revised to upgrade the revised standard GB/T 50779 is expected to be promulgated this year, compared with the 2012 version of the GB was revised to GB/T, the name of the "petrochemical control room explosion-resistant design specifications" was revised from the "Petrochemical Building Explosion Resistant Design Standards (《》). In addition, in addition to the central control room, some LNG plants also have on-site cabinet rooms, the above three requirements do not mention on-site cabinet rooms, especially unattended on-site cabinet rooms, to which reference can be made to SH/T 3006-2012 "Petrochemical Control Room Design Specification" and HG/T20508-2014 "Control Room Design Specification" and other relevant standards. To summarize, whether a building needs to consider explosion resistance depends mainly on whether the building is located in the area of explosion risk and whether there are people staying in the building for a long time. At present, the new central control room and other important buildings are generally arranged away from the location of the plant area, its need for explosion should be based on the explosion risk assessment to determine the control room in the LNG process plant area, manned cabinets and other buildings are important facilities, but also a concentration of personnel, relatively close to the fire hazardous equipment, in order to prevent the plant area of the occurrence of fires, explosions and other accidents caused by the damage to it, therefore Provides that it is appropriate to carry out anti-explosion design.
Second, the explosion-proof design of the new LNG plant control room
The explosion-proof design of the control room needs to be arranged, building structure and HVAC and other three aspects of attention. This is a little expansion of the description is as follows.
Should be in line with the current national standard "Petrochemical Enterprise Design Fire Code" GB50160 of the relevant provisions, should be arranged in the non-explosive hazardous areas, and can be adjusted according to the results of the safety analysis (assessment) report, and should be consistent with the following requirements:
(1) anti-explosive control room is appropriate to be arranged on the side of the process equipment, the surrounding should not be arranged at the same time the A and B devices, and the arrangement of the control room should not be lower than the adjacent site. Control room site should not be lower than the floor of the adjacent device area. (Based on the prevention of combustible gases in the control room around the collection of considerations)
2) anti-explosive control room should be set up independently, shall not be combined with non-explosive building construction. (Based on the avoidance of device explosion state, non-explosive buildings may produce debris blocking the control room personnel evacuation channel considerations)
3) anti-explosive control room should be set up in at least two directions of the safety of the personnel exit, and shall not be directly facing the A, B type of process equipment. (Requirements of the current national standard Building Design Fire Prevention Code GB50016-2014 (2018 edition); based on the consideration of improving the possibility of personnel evacuation, it is required to set up evacuation ports in different directions of the building)
(1) Architectural design
(1) The building level of the explosion-resistant control room shall not be equipped with an assembled overhead thermal insulation structure, and the height of the daughter wall shall be set up to meet the Roof waterproof construction requirements in the case of the minimum value, and it is appropriate to use reinforced concrete structure.
2) building facades should not be set up awnings, eaves and other ancillary structures.
3) The building shall not be set up deformation joints.
4) The external wall facing the A and B process device should be a solid explosion-resistant wall. Need to open holes in the wall, should be after the explosion-resistant calculations.
5) in the personnel channel door on the indoor side, should be set up to isolate the front room. (The main purpose of setting up the isolation chamber is to effectively maintain a positive pressure (explosion-proof measures) environment inside; at the same time, when the outer door is damaged under the action of the blast load, become a second protective system.)
6) cable entry holes shall not be opened on the exterior wall above the bottom surface under the movable floor. Foundation wall holes should be taken to seal measures and meet the requirements of anti-explosion. (Mainly to prevent the device explosion generated by the overpressure through the cable slot box and the building exterior wall openings into the room.)
7) operation room, the difference in height of the ground should not be less than 600mm, of which the movable floor under the ground and the height difference between the outdoor ground should not be less than 300mm. air-conditioning equipment room indoor and outdoor difference in height should not be less than 300mm.
(2) building windows and doors
Control of the outdoor door, the isolation of the indoor door in front of the calculation of the load, the direction of the openings, automatic door closers
(3) structural design
The strength of concrete, tensile strength of steel, yield strength, maximum tensile strength of the total elongation and explosion-resistant structural components of the reinforcement strength level and the area of reinforcement, etc. are clearly defined.
Explosion control room important room, general room air conditioning system, ventilation and air conditioning equipment interlock, fresh air and return air filtration requirements, standby air conditioning requirements, requirements for explosion control room smoke exhaust system are clearly defined, specific can check the above specifications.
Third, the existing LNG plant control room renovation ideas
In order to enhance the explosion shock wave hazard area does not meet the requirements of the plant's existing internal building explosion resistance to prevent major injuries, it is desirable to carry out its anti-explosive governance, now based on the existing norms listed above on the principle of the relevant governance requirements are organized as follows:
1) when the building is subjected to an explosion shock wave overpressure ≥ 6.9kPa or impulse ≥ 207kPa?ms, and no anti-explosive design, the building should be anti-explosive governance.
2) building anti-detonation management should be given priority to consider the withdrawal of the building program. Can not be realized when unattended, the building should be anti-detonation management. Anti-explosive reinforcement of high engineering costs or anti-explosive reinforcement after the transformation of the building is difficult to meet the requirements of GB50016, GB50160 and other current national standards, should be considered to move the building to the explosion of the impact of the hazard level of the region for the lower level.
3) for other existing buildings with insufficient blast resistance, should be based on the number of people in the building, the importance of the building, building structure type, the size of the blast shock wave and the degree of damage to the building, such as batches of anti-explosive management.
4) When a part of the existing building requires anti-explosive reinforcement, the building as a whole should be structural safety accounting, accounting should be taken into account non-explosive part of the explosion after the destruction of the anti-explosive reinforcement part of the role and impact.
5) should be based on the results of structural safety accounting of buildings, production and operation of the constraints of the link, the current state of the building and site conditions, weighing the applicability, implementability and economy and other factors, the development of a comprehensive and complete anti-explosive management program. Can choose to build a new anti-explosive building or existing buildings for anti-explosive reinforcement.
6) of the existing buildings for anti-detonation reinforcement, direct reinforcement can be used (such as various types of structural reinforcement, anti-detonation coating method, etc.) or indirect reinforcement (such as the addition of pivot reinforcement method, anti-detonation shelter method, etc.), the relevant requirements of the reinforcement method should meet the provisions of GB/T50779 (latest).
7) When the building reinforced concrete components (reinforced concrete columns, beams, plates) do not meet the safety requirements of blast resistance, can be used in various types of structural reinforcement or indirect reinforcement method, such as additional pivot reinforcement method, increase the cross-section reinforcement method, wrapped steel reinforcement method, paste compliant material reinforcement method and additional shear wall method.
8) of the existing building walls for anti-explosive reinforcement, it is appropriate to choose the anti-explosive coating method. Explosion-resistant coating method of reinforcement, it is appropriate to spray on the inside of the building explosion-resistant coating, spraying thickness should be determined according to the results of calculations.
9) anti-explosive coating dynamic performance should be verified by other explosive shock wave test (the role of the anti-explosive coating on the peak reflective pressure shall not be less than 300kPa, positive pressure effect time shall not be less than 150ms), and to provide explosive shock wave test report. Not verified by the gas explosion shock test anti-explosive coating shall not be used for petrochemical buildings anti-explosive management.
10) for the use of direct reinforcement methods can not meet the requirements of explosion-resistant buildings, can be used to anti-explosion shelter method. Ordinary brick buildings are suitable for anti-explosive shelter method for anti-explosive reinforcement.
11) for a smaller area, the transformation of buildings with great difficulty, modular mobile anti-explosive shelter facilities can be used.
12) prudent use of buildings and explosive sources between the addition of anti-explosive wall of anti-explosive reinforcement methods. If you really need to use this method, the CFD method should be detailed simulation of the explosion shock wave propagation process, and special demonstration.
Fourth, there has been an LNG plant control room renovation example
A LNG project in North China was completed and put into operation in 2008, and in 2010 for technological transformation, adding the second phase of the liquefaction plant design and construction, the second phase of the plant was completed and put into operation in 2012. Combined with the "three-year action plan for special rectification of national security" (State Council Security Committee No. 20203), the second level of standardization review and the renewal of the safety production and operation license of the relevant requirements of the control room, the need for the LNG plant original control room for the transformation of the anti-explosive control room.
Combined with the requirements of the Safety Commission Office No. 3, the problems that existed in the control room before remodeling are (see the floor plan shown in Figure 1 above):
(1) the original control room and capacitor room, power distribution room for the merger of the building, not independently;
(2) the original control room is a steel structure, and there are non-explosion-resistant windows in the direction of the hazardous area;
(3) the original control room is in the production area and the walls are not explosion-resistant. (3) the original control room in the production area and the wall is not explosion-proof solid wall, not set up isolation of the front room, and the upper part of the door with eaves, non-explosion-proof building.
After discussion, the options for renovation are:
(1) in the original control room and the hazardous area between the addition of explosion-resistant wall;
(2) site reconstruction of explosion-resistant control room;
(3) in the original site of the reconstruction of explosion-resistant control room.
The local Emergency Management Agency does not recognize the addition of blast-resistant walls, so option 1 can not be implemented. Because of other locations within the field can not meet the size and location of the new anti-explosive control room requirements, so program 2 can not be implemented. Ultimately, only in situ remodeling program is feasible.
1) Separate the control room and power distribution room into a separate building;
2) change the control room structure from steel to reinforced concrete structure;
3) change the control room walls from rock wool panels to reinforced concrete solid wall;
4) add isolation in the doorway of the front room;
5) change the control room door to explosion-proof door, not set windows;
6) Adding redundant air conditioning, fresh air, and fire exhaust systems.
The control room renovation period is long, need to consider the normal operation of the plant under the circumstances of the transformation. Thus, the establishment of a temporary control room in advance, before the transformation of the system will be relocated to a temporary control room (annual downtime maintenance); and before the transformation of the control cabinet and the relevant control cables to do hard protection (temporary isolation room), and the installation of temporary air-conditioning to ensure that the control cabinet is at a constant temperature and humidity; involved in the control cabinet and the relevant control loop one by one to carry out the process safety analysis to determine the impact and countermeasures caused by the problems of each control loop The process safety analysis of the involved control cabinets and related control circuits was carried out one by one to determine the impact of each control circuit problem and countermeasures, formulate the "Process Prevention and Control Program", and provide training to all personnel before the formal start of the transformation. By analyzing the control logic of each system and the impact of communication interruptions on the site, we formulated a non-stop relocation plan to ensure the normal operation of the LNG plant during the entire transformation period.
V. Conclusion
Currently, the state attaches great importance to the safety of petrochemical and other industries. In this paper, the author combined with the service of the LNG plant control room renovation of the actual case on the relevant norms of the LNG control room explosion-resistant design requirements and has been built on the existing LNG plant how to carry out explosion-resistant renovation and other summaries, the cases cited in the text from the team of the real rectification of the case, taking into account the differences in actual operation of the LNG plant around the world, it is difficult to summarize all, the purpose of the brickbats, to cause colleagues in the industry to explore The purpose of these summaries is to draw attention to the differences in the actual operation of LNG installations in different parts of the world, and to arouse the discussion and exchange of ideas and attention of industry colleagues.