Design of automatic warehouse fire control system.
Abstract: With the more and more extensive application of automated warehouse, the supporting fire protection system is gradually improved. This paper introduces two kinds of fire extinguishing systems, namely, pre-spraying fire extinguishing system and superfine dry powder fire extinguishing system, and puts forward the selection and arrangement ideas of fire extinguishing system in three-dimensional warehouse.
Key words: three-dimensional warehouse, fire fighting system, water spray fire fighting, ultra-fine dry powder fire fighting
In recent years, the demand for automated three-dimensional warehouse is strong and develops rapidly. The shelf height of automated warehouse is generally above 12m, which has the characteristics of high height, large space, large area, dense storage and large storage capacity. And the requirements for the fire fighting system are very high. Otherwise, once a fire breaks out, it is easy to spread along the shelves layer by layer, and it is difficult to put out. If there is no efficient and reliable fire fighting system, it will easily cause serious economic losses.
With the more and more extensive application of automated warehouse in various industries, the fire laws and regulations and fire departments put forward higher requirements and related regulations for the fire protection system of automated warehouse, and the design and implementation of the fire protection system of automated warehouse are gradually improving.
At present, there are two main fire fighting systems in the warehouse: pre-spraying and superfine dry powder. Water spray fire extinguishing system before production
Article 8.7. 1 of the National Code for Fire Protection Design of Buildings (GB500 16—2006) stipulates that closed automatic sprinkler should be installed in the elevated warehouse of combustible and refractory articles. When designing an automated warehouse, it is generally necessary to select an automatic sprinkler system according to the type of materials stored. The water spray fire extinguishing system uses a large amount of water to directly spray on the protected object to extinguish the fire, and at the same time effectively reduces the temperature after the fire, which can effectively extinguish the Class A fire. It may be a good fire extinguishing system for protected objects that are not afraid of water and places with large water supply. However, the water spray fire extinguishing system is not suitable for products that explode in water, or accelerate combustion, undergo violent chemical reactions, or produce toxic and harmful substances.
1, working principle
Under normal monitoring condition, the pipeline of pre-action sprinkler system is dry. It is filled with a certain amount of compressed air for monitoring, and its working state is monitored by the fire linkage alarm host. When there is a fire or hidden danger in any part of the warehouse, the air sampling detector set in the warehouse confirms the occurrence of the fire through multi-level alarm. When the alarm is at the level of 1 (i.e. early warning period). The alarm system prompts that there is something abnormal in the alarm area. At this time, the fire is still in the early stage of no visible smoke, and the alarm host will send out an audible and visual alarm in time to remind the fire management personnel that the reservoir area is abnormal, and the fire management personnel will find out the situation at the scene according to the location of the alarm area and deal with the fire hidden danger in time. If the fire continues to develop, when the fire air sampling detector enters the three-level alarm (that is, the alarm period), the alarm system linkage control equipment starts the fire pump, so that the pipeline in front of the pre-action valve device is filled with water for standby. Only when the fire causes the air sampling detector to enter the four-level alarm (that is, the fire period), the pre-action valve is opened to fill the water spraying pipe network with water. When the pressure reaches a predetermined value, the water injection signal is fed back to the fire linkage alarm host through the water flow indicator. If an open flame burns in a certain place and the temperature rises to a set value, the glass ball of the nozzle will automatically explode and spray water from the corresponding nozzle to extinguish the fire.
2. System characteristics
Pre-water spray fire extinguishing system has the following main features:
(1) Safe operation. When the pipe network is damaged at ordinary times, the system can automatically monitor and remind maintenance. If the alarm system makes the system fill water by mistake, there will be no water damage because the pipeline is sealed.
(2) The pre-action sprinkler system takes water as the medium, which is convenient to use, low in cost and easy to obtain, and is beneficial to reducing the system cost;
(3) Convenient maintenance. The system is connected by steel pipes, and the valves and nozzles do not need to be replaced regularly. In addition, the fire extinguishing medium is water, so as long as the fire pool is kept clean, there is no need to change the medium regularly, which will not cause repeated investment and reduce the maintenance cost;
(4) It is not suitable for the three-dimensional warehouse of high-value goods, because once the system fails or a small fire occurs, it will cause huge economic losses;
(5) If water resources are tight and fire water is stored for a long time, the deterioration of water quality will increase the maintenance cost;
(6) Long response time. When a fire breaks out, it takes some time for water to get from the pool to the real fire point, so it can't be put out in time;
(7) The fire fighting system is generally fixed on the high-rise shelves of the three-dimensional warehouse, and the static load and dynamic load bring great difficulty to the shelf design, especially considering the dynamic load factors such as earthquakes;
(8) The relevant national codes and standards lag behind the rapid development of modern logistics industry application, and most fire protection design units design according to Code for Fire Protection Design of Buildings (GB500 16-2006), Code for Design of Automatic Sprinkler Fire Extinguishing System (GB50084-200 1) and their working experience, which has certain risks.
3. Implementation case
The water spraying system before production consists of alarm system and water spraying system. In the design process, the quantity, specifications and flow of related components should be designed according to the requirements of the specification.
The alarm components, nozzles and fire pipes of the pre-action automatic sprinkler system are supported by shelves, and the design should be synchronized with the shelf design of the elevated warehouse. The overall height and width of the shelf should reserve space for installing fire pipes to meet the space requirements of relevant fire codes.
Superfine dry powder fire extinguishing system
Ultra-fine dry powder fire extinguishing agent is produced with the development of ultra-fine grinding technology in recent years. The ministerial standard GA578-2005 stipulates that 90% of the particle size is 20 microns or less, and the smaller the particle size, the larger the specific surface area. Ultra-fine dry powder fire extinguishing technology embodies the advanced fire extinguishing technology concept of "quick response, early fighting and high efficiency", which is the frontier technology that countries all over the world are scrambling to study and has developed rapidly since it came out.
The application of superfine dry powder fire extinguishing method in three-dimensional warehouse is increasing gradually, and it is a better choice from the perspective of overall investment and fire extinguishing efficiency. However, due to the special function of shelves in three-dimensional warehouses, not all ultra-fine dry powder is suitable for use in overhead warehouses. At present, there are two main driving modes for ultra-fine dry powder devices produced in China:
① Driven by gas. ABC dry powder is installed in the fire extinguishing device, and its main fire extinguishing component is ammonium phosphate, and 90% of the powder particles are above 20μ m. As far as chemical fire extinguishing agent is concerned, its particle size is inversely proportional to the fire extinguishing efficiency, that is, the smaller the particle size, the higher the fire extinguishing efficiency. Therefore. Its extinguishing efficiency is only 1/6 ~ 1/4 of that of the real superfine dry powder extinguishing agent. Due to the short injection time of this fire extinguishing device (
② Driven by nitrogen. The high-pressure nitrogen in the nitrogen cylinder group enters the ultra-fine dry powder fire extinguishing agent storage tank, and the fire extinguishing agent is pushed out by the nozzle arranged in the protected area through the conveying pipeline to quickly extinguish the fire. This kind of fire extinguishing device is filled with composite materials based on inorganic polymers as fire extinguishing components, and the fire extinguishing agent can be completely immersed or partially immersed. The driving parts are installed on the shelves, so the impact on the shelves in case of fire is small, and the strength can be properly considered when designing the shelves.
1, working principle
The automatic fire extinguishing device for ultra-fine dry powder is mainly composed of fire extinguishing agent storage tank filled with ultra-fine dry powder and driving gas, lifting ring or fixed disc seat, nozzle, pressure indicator, temperature sensing element, thermal initiator and electric initiator. According to the needs of the application, a signal feedback device and a heat collecting cover can be added. Automatic start-up of superfine dry powder automatic fire extinguishing device has three start-up modes: automatic electric control, manual electric control and constant temperature start-up. It is linked with any kind of fire alarm system to form an automatic fire extinguishing system with superfine dry powder without pipe network.
(1) Automatic start of electronic control
When the fire extinguishing controller connected with the fire extinguishing device is set in the "automatic" position, the fire extinguishing device is in the automatic control state. When there is a fire in the protected area, the fire alarm control system sends out an acousto-optic alarm signal after receiving the fire signal of the detector, and starts the fire extinguishing device to release the superfine dry powder extinguishing agent after delaying the set time. The signal feedback device feeds back the fire extinguishing agent release signal to the fire alarm controller.
(2) Electronic control and manual start-up
When there is a fire in the protected area, press the start button of the fire alarm controller or the gas fire extinguishing control panel next to the protected area, and start the fire extinguishing device according to the specified procedures.
(3) Constant temperature startup
When a fire breaks out in the protected area and the ambient temperature rises to the rated working temperature set by the fire extinguishing device (set at 68℃), the fire extinguishing device will automatically start to release ultra-fine dry powder extinguishing agent to extinguish the fire regardless of whether the fire alarm controller works or not.
2. System characteristics
The fire extinguishing mechanism of superfine dry powder is mainly chemical fire extinguishing, supplemented by physical fire extinguishing, and has the following characteristics:
(1) Among all fire extinguishing agents, it has excellent performance and has a strong inhibitory effect on flaming combustion. When superfine dry powder is mixed with flame. Fire-extinguishing components quickly capture combustion free radicals, so that the consumption rate of free radicals is faster than the production rate, the combustion free radicals are quickly discharged, the chain reaction process is terminated, and the flame is quickly extinguished;
(2) Ultra-fine dry powder has good fire extinguishing speed and efficiency for flame combustion, and also has good fire extinguishing effect for surface combustion (smoldering) of general solid materials. When the ultra-fine dry powder crystal powder comes into contact with the burning surface, a series of chemical reactions occur, and it melts at high temperature on the solid surface to form a glassy coating, which separates the solid surface from the surrounding air and suffocates and burns;
(3) When ultra-fine dry powder is used to extinguish the fire, the dense cloud-like powder is mixed with the flame to decompose and absorb heat, which can absorb part of the heat of the flame. Some inert gases produced by these decomposition reactions, such as carbon dioxide and water vapor, dilute the oxygen concentration in the combustion zone and weaken the combustion reaction of the fire;
(4) The testing results of authoritative departments show that the extinguishing concentration of superfine dry powder extinguishing agent is 64.4 g/m3, which is the lowest extinguishing concentration, the highest extinguishing efficiency and the fastest extinguishing speed among the identified extinguishing agents at home and abroad.
(5) Ultrafine dry powder is environmentally friendly, with zero ozone depletion potential (ODP) and zero greenhouse effect potential (GWP), which is non-irritating to human skin, non-corrosive to protected objects, and non-toxic;
(6) Ultra-fine dry powder high-efficiency fire extinguishing agent is the only dry powder fire extinguishing agent that can realize total flooding, because of its small particle size, light weight, good fluidity and thermal stability.
(7) The residue after fire extinguishing is easy to clean.
3. Implementation case
Ultra-fine dry powder fire extinguishing system consists of alarm system and automatic pressure storage fire extinguishing device. In the design process, the quantity, specifications and dry powder dosage of related components should be designed according to the requirements of relevant specifications. The alarm system is the same as the pre-action spray system, and generally adopts the very early air sampling smoke alarm system.
The alarm components, fire extinguishing devices and their supports of superfine dry powder fire extinguishing system are supported by shelves, and the design should be synchronized with the shelf design of overhead warehouse. Installation space should be reserved according to the overall height and width of the shelf, and meet the space requirements of relevant fire codes. This kind of fire fighting device only occupies the top floor in height, and its width is the same as the space required by automatic sprinkler system. The width and size of the fire extinguishing device can be changed according to the overall design, as long as a large dose is guaranteed.
In the automatic logistics system, the fire fighting work in the warehouse is important and urgent. In the actual fire prevention and extinguishing work, users need to select fire extinguishing agents and fire extinguishing equipment according to the actual use requirements. At the same time, the design and implementation units should ensure the stability and reliability of the fire protection system, and the fire department should strictly review and check.
I hope I can help you.