A system and method for measuring the efficiency of building smoke evacuation

Abstract

The application discloses a kind of measurement system and method suitable for building smoke exhaust efficiency, belong to fire science and fire engineering technical field, the system includes processor, building body, be set on the building body and be connected with processor for being inhaled into tracer gas for building body's gas conveying mechanism, temperature sensor, speed sensor and tracer gas sensor being set in smoke outlet, and combustion source and fan being set in building body;The method includes combustion source ignition and tracer gas input, smoke exhaust measurement, and total smoke exhaust efficiency calculation.The application is based on mechanical smoke exhaust system design smoke exhaust volume and fire smoke production volume ratio of smoke exhaust volume redundancy, convection heat released by combustion source and convection heat removal capacity of smoke outlet, and combine the concentration change of tracer gas, build the relationship of smoke exhaust volume redundancy, convection heat removal rate and tracer gas smoke exhaust rate and total smoke exhaust efficiency, establish smoke exhaust system efficiency measurement method and system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fire science and fire engineering, and particularly relates to a system and method for measuring the smoke exhaust efficiency of a building. BACKGROUND

[0002] When a building catches fire, the combustion of combustible materials releases a large amount of high-temperature toxic smoke and a large amount of heat. Building fire smoke is the main cause of casualties because the harmful components of the smoke or lack of oxygen directly poisons or suffocates people; the light-shielding effect of the smoke makes it difficult for people to escape and be trapped in the fire area; the high-temperature hazard of the smoke can cause the strength of metal materials to decrease, thereby causing the structure to collapse and causing casualties. Smoke not only causes casualties, but also brings difficulties to firefighters, so it is particularly important to set up a reasonable and effective smoke exhaust system, such as a smoke exhaust port.

[0003] Due to the influence of factors such as the smoke exhaust port, the combustion source, the scale, and the relative position relationship during an actual fire, the actual smoke exhaust efficiency cannot be evaluated only by the smoke exhaust parameter, and the smoke exhaust efficiency of the smoke exhaust system cannot be quantitatively judged, which is a technical problem to be solved by the skilled in the art.

[0004] Therefore, the present application provides a system and method for measuring the smoke exhaust efficiency of a building to at least solve some of the above technical problems. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a system and method for measuring the smoke exhaust efficiency of a building to at least solve some of the above technical problems.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] A system for measuring the smoke exhaust efficiency of a building, comprising a processor, a building body, a smoke exhaust port provided on the building body, a gas supply mechanism connected to the building body and connected to the processor for supplying a tracer gas into the building body, a temperature sensor, a speed sensor, and a tracer gas sensor provided in the smoke exhaust port, and a combustion source and a fan provided in the building body; the processor is connected to the temperature sensor, the speed sensor, the tracer gas sensor, and the fan, respectively.

[0008] Further, the gas supply mechanism comprises a gas storage tank for storing the tracer gas, and a gas supply pipe connected to the gas storage tank and connected to the building body, and an electromagnetic valve and a gas flow meter connected to the processor are provided on the gas supply pipe.

[0009] Further, the tracer gas is sulfur hexafluoride, and the tracer gas sensor is a sulfur hexafluoride sensor.

[0010] Further, the combustion source is an alcohol stove using alcohol as fuel.

[0011] Further, at least two temperature sensors, one velocity sensor and two tracer gas sensors are arranged in each smoke outlet.

[0012] A method for measuring the smoke exhaust efficiency of a building, comprising the following steps:

[0013] Step 1, igniting a combustion source at a typical position in the building, and simultaneously turning on the gas feeding mechanism and the fan, and continuously feeding tracer gas into the plume of the combustion source;

[0014] Step 2, within 60 seconds after the combustion source is ignited, starting the smoke exhaust duct fan and the smoke outlet to exhaust smoke, and turning on the temperature sensor, the velocity sensor and the tracer gas sensor to measure the temperature and flow rate of the exhaust smoke, and the concentration of the tracer gas exhausted with the smoke, until the combustion source is extinguished and the gas feeding mechanism is turned off;

[0015] Step 3, feeding back the temperature and flow rate of the exhaust smoke, and the concentration of the tracer gas exhausted with the smoke to the processor, and combining with the feeding concentration of the tracer gas, respectively calculating the smoke exhaust volume redundancy rate η V , the convection heat removal rate η CHR and the tracer gas exhaust rate η TG , and then weighting the smoke exhaust volume redundancy rate η V , the convection heat removal rate η CHR and the tracer gas exhaust rate η TG to obtain the total smoke exhaust efficiency η.

[0016] Further, the calculation formula of the total smoke exhaust efficiency is: η = α1η V + α2η CHR + α3η TG , wherein α1, α2 and α3 are weight factors, α1 is 0.2-0.3, α2 is 0.4-0.5, and α3 is 0.2-0.4.

[0017] Further, α1 is 0.3, α2 is 0.5, and α3 is 0.2.

[0018] Further, the calculation formula of the smoke exhaust volume redundancy rate η V is: η V = (Vp-V) / V, wherein V p is the air volume of the smoke exhaust fan, and V is the smoke production volume of the fire.

[0019] Further, the calculation formula of the tracer gas exhaust rate η TG is: η TG = Q O / Q α , wherein Qo represents the amount of tracer gas discharged by the smoke exhaust system per unit time, Q α represents the amount of tracer gas released to the building per unit time.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] When a fire occurs, not only smoke but also a large amount of heat will be generated, but due to space limitations, the generated heat cannot be completely discharged. Therefore, the present application designs the smoke exhaust volume redundancy ratio of the smoke exhaust volume to the fire smoke generation volume, the convective heat released by the combustion source, and the convective heat discharge amount of the smoke exhaust port, and combines the concentration change of the tracer gas as the smoke exhaust rate index to build the relationship between the smoke exhaust volume redundancy rate, the convective heat discharge rate, and the tracer gas smoke exhaust rate and the total smoke exhaust efficiency, and further establishes the building smoke exhaust system efficiency measurement method and system, which is scientific and reasonable in design and convenient to use.

[0022] The present application designs a measurement system for the established building smoke exhaust efficiency measurement method, calculates the corresponding smoke exhaust volume redundancy rate, convective heat discharge rate, and tracer gas smoke exhaust rate through the data measured by each sensor, and simultaneously sets up a gas conveying mechanism to facilitate the continuous introduction of tracer gas into the building and the synchronous discharge with the combustion source plume. Compared with the existing smoke exhaust measurement method and system, the measurement results of the present application are scientific, reasonable, and accurate and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 It is a structural diagram of the measurement system of the present application.

[0024] Fig. 2 It is a gas conveying mechanism diagram of the measurement system of the present application.

[0025] Fig. 3 It is a connection diagram of each electrical device of the measurement system of the present application.

[0026] Among them, the name corresponding to the reference sign is:

[0027] 1-processor, 2-gas conveying mechanism, 3-smoke exhaust port, 4-building, 5-temperature sensor, 6-speed sensor, 7-tracer gas sensor, 8-combustion source, 9-fan, 21-gas storage tank, 22-gas conveying pipe, 23-solenoid valve, 24-gas flow meter. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0029] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; of course, it can also be mechanically connected, or it can also be electrically connected; in addition, it can also be directly connected, or it can also be indirectly connected through an intermediate medium, or it can also be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] As Figs. 1-3 shown, the present application provides a kind of measurement system suitable for building smoke exhaust efficiency, including processor 1, building body 4, be arranged on building body 4 and be arranged in building body 4 and be connected to processor 1 for being filled into tracer gas for building body 4 in gas conveying mechanism 2, temperature sensor 5, speed sensor 6 and tracer gas sensor 7 being arranged in smoke outlet 3, and combustion source 8 and fan 9 being arranged in building body 4;Processor 1 is connected with temperature sensor 5, speed sensor 6, tracer gas sensor 7 and fan 9 respectively.The present application calculates corresponding smoke exhaust redundancy rate, convection heat removal rate and tracer gas smoke exhaust rate by the data measured by each sensor, while setting up gas conveying mechanism 2 to facilitate tracer gas to continue to enter building and be discharged with combustion source plume synchronously.Compared with the prior art smoke exhaust measurement method and system, the measurement result of the present application is scientific and reasonable and accurate and reliable.

[0032] During the process of discharging smoke through the smoke outlet, due to various reasons, the air accounts for a part of the gas discharged through the smoke outlet, rather than all the smoke. Therefore, the smoke discharging efficiency of the smoke outlet is also an important indicator for measuring the smoke discharging capacity of the smoke discharging system. As a stable and traceable gas, the tracer gas can make up for the above shortcomings when applied to the measurement of the smoke discharging efficiency. Therefore, the measurement system of the present application continuously inputs the tracer gas with a constant flow rate through the gas conveying mechanism 2 during the entire process of test measurement. The gas conveying mechanism 2 includes a gas storage tank 21 and a gas conveying pipe 22 connected with the gas storage tank 21 and connected with the building body 4, and the gas conveying pipe 22 is provided with an electromagnetic valve 23 and a gas flow meter 24 connected with the processor 1 respectively. The tracer gas is stored in the gas storage tank 21 and connected with the building body 4 through the gas conveying pipe 22, and the tracer gas is continuously inputted by opening the electromagnetic valve 23, and the gas flow meter 24 on the gas conveying pipe 22 measures the flow rate of the gas conveying mechanism 2 per unit time of the tracer gas and feeds back to the processor 1 in real time. After the tracer gas is inputted, the fan 9 is started to diffuse uniformly. The tracer gas is sulfur hexafluoride, and the tracer gas sensor 8 is a sulfur hexafluoride sensor. Sulfur hexafluoride has the advantages of non-toxicity, non-corrosion, non-flammability, non-explosiveness and non-chemical reaction with surrounding gas and substances, and can be used as a tracer gas to simulate the heat discharge. When sulfur hexafluoride is selected as the tracer gas, the input amount is 1.0-3.0g per square meter of indoor space. The combustion source 8 is an alcohol stove using alcohol as fuel, which not only meets the needs of combustion and smoke discharging, but also has the characteristics of cleanliness and greenness, and the products generated by combustion can be directly discharged into the atmosphere.

[0033] The measurement system of the present application is provided with at least two temperature sensors 5, one speed sensor 6 and two tracer gas sensors 7 in each smoke outlet 3, so as to improve the measurement accuracy. The speed sensor 6 is a pitot tube. In particular, the smoke outlet design in the measurement method of the smoke outlet heat discharging efficiency measurement system of the patent number CN106198091A and the patent name of the applicant's previous application is adopted, each smoke outlet is divided into two or more than two smoke units with equal area, and at least two temperature sensors 5, one speed sensor 6 and two tracer gas sensors 7 are arranged in each smoke unit.

[0034] A measurement method suitable for building smoke discharging efficiency, comprising the following steps:

[0035] Step 1, igniting the combustion source at a typical position in the building body, and simultaneously opening the gas conveying mechanism and the fan to continuously add the tracer gas into the plume of the combustion source;

[0036] Step 2: Within 60 seconds after the combustion source is ignited, turn on the exhaust duct fan and exhaust port to start exhausting smoke. Turn on the temperature sensor, speed sensor, and tracer gas sensor to measure the temperature and flow rate of the exhaust gas, as well as the concentration of tracer gas discharged with the exhaust gas, until the combustion source finishes burning and the gas supply mechanism is turned off.

[0037] Step 3: Feed back the temperature and flow rate of the exhaust gas, as well as the concentration of the tracer gas discharged with the exhaust gas, to the processor, and calculate the exhaust redundancy rate η based on the introduced concentration of the tracer gas. V Convection heat rate η CHR and tracer gas exhaust rate η TG Then, the smoke emission redundancy rate η V Convection heat rate η CHR and tracer gas exhaust rate η TG The total smoke emission efficiency η is obtained by weighting.

[0038] When a fire occurs, not only smoke is produced, but also a large amount of heat is generated. However, due to space limitations, 100% of the generated heat cannot be discharged. Therefore, this invention, based on the ratio of smoke exhaust volume to fire smoke production in a mechanical smoke exhaust system design, the redundancy of smoke exhaust volume, the convective heat released by the combustion source, and the convective heat dissipation at the smoke exhaust outlet, and combined with the concentration change of tracer gas as an indicator of smoke exhaust rate, constructs the relationship between smoke exhaust volume redundancy rate, convective heat dissipation rate, tracer gas smoke exhaust rate, and total smoke exhaust efficiency. This leads to the establishment of a method and system for measuring the efficiency of a building's smoke exhaust system, which is scientifically designed, reasonable, and easy to use.

[0039] In the measurement method of this invention, the relationship between the smoke emission redundancy rate, the convective heat dissipation rate, the tracer gas smoke emission rate, and the total smoke emission efficiency is established. The formula for calculating the total smoke emission efficiency η is: η=α1η V +α2η CHR +α3η TG Wherein, α1, α2, and α3 are weighting factors, with α1 ranging from 0.2 to 0.3, α2 from 0.4 to 0.5, and α3 from 0.2 to 0.4. Preferably, α1 is 0.3, α2 is 0.5, and α3 is 0.2. The exhaust redundancy rate, convective heat exhaust rate, and tracer gas exhaust rate are used as the three weighting factors for the total exhaust efficiency. The weight ratios of the convective heat exhaust rate, tracer gas exhaust rate, and exhaust redundancy rate decrease sequentially. Combining these three calculated rates, the final exhaust efficiency is obtained.

[0040] In the measurement method of this invention, the smoke emission redundancy rate η V The calculation formula is: η V = (Vp-V) / V, where V p V represents the air volume of the smoke exhaust fan, and V represents the smoke production during a fire. The gas discharged from the smoke exhaust outlet contains a portion of air, not entirely smoke. Therefore, the air volume V of the smoke exhaust fan in the smoke exhaust system is... pThe percentage of the fire smoke production V is defined as the smoke exhaust redundancy rate of the smoke exhaust system, and can better reflect the smoke exhaust efficiency. The smoke exhaust fan air volume V p The speed is measured by the sensor 6, and the fire smoke production V is calculated according to the axisymmetric plume calculation formula of the smoke plume mass flow in the building smoke exhaust system technical standard. The measurement instruments required for measuring the data such as the flame limit height and the height from the fuel surface to the smoke layer bottom are arranged in the building body 4 of the measurement system, and each measurement instrument is connected with the processor 1.

[0041] In the measurement method, the calculation method of the convection heat removal rate η CHR in the patent number CN106384165B and the patent name of the smoke exhaust efficiency evaluation method based on the orthogonal analysis method applied by the applicant in the early stage is adopted, and specifically, the calculation method is as follows: Wherein is the total amount of convection heat removal of the smoke exhaust port, Q fire is the total heat release of the combustion source, and Q fire =mΔH c , m is the mass of the combustion source, and ΔH c is the combustion heat value of the combustion source;

[0042] In particular, The calculation process is as follows: the smoke gas temperature and flow rate of each smoke exhaust port are measured by the temperature sensor 5 and the speed sensor 6 respectively, the convection heat removal rate Q CHRR of each smoke exhaust port is calculated according to the following formula, and the instantaneous heat removal performance of the corresponding smoke exhaust port is obtained: Wherein c p is the specific heat of air, is the smoke gas mass flow rate passing through the i-th smoke exhaust port unit, and ρ=1.2kg / m 3 , S i is the area of the i-th smoke exhaust port unit, and ΔT i is the average temperature rise of the smoke gas in the i-th smoke exhaust port unit; is measured by the speed sensor 6, and ΔT i is measured by the temperature sensor 5, and the data is obtained by average processing of the processor 1;

[0043] The convection heat removal rates Q CHRR of each smoke exhaust port are superimposed, and the overall convection heat removal rate of the smoke gas control system is obtained, that is M is the total number of the opened smoke exhaust ports, and j is the j-th opened smoke exhaust port;

[0044] Integrate Q with respect to time, and the total amount of convection heat removal through the smoke exhaust port is obtained, that is

[0045] The total amount of convective heat removal Divided by the convective component Q of the heat release of the fire source conv The convective heat removal efficiency η is obtained CHR That is: Q conv The convective component of the heat release of the fire source, that is, the heat in the form of convection entering the smoke layer through the fire flow, for most fuels, the value of Q conv is Q conv = 0.7Q fire , Q fire is the total heat release of the fire source, which can be calculated by the formula Q fire = mΔH c , wherein m is the mass of the combustion source, and ΔH c is the combustion heat value of the combustion source.

[0046] In the measurement method of the present application, the tracer gas smoke exhaust rate η TG is calculated by the formula: η TG = Q O / Q α , wherein Q o represents the amount of tracer gas discharged by the smoke exhaust system per unit time, and Q α represents the amount of tracer gas released to the building per unit time. The amount of tracer gas discharged by the smoke exhaust system per unit time Q o is obtained by multiplying the tracer gas discharge concentration of the smoke exhaust port measured by the tracer gas sensor 7 by the volume of the smoke exhaust port, Q α is obtained by multiplying the tracer gas introduction concentration measured by the gas flow meter 24 of the gas supply mechanism 2 by the volume of the building. When sulfur hexafluoride is used as the tracer gas, the amount of tracer gas discharged by the smoke exhaust system per unit time Q o is obtained by multiplying the sulfur hexafluoride discharge concentration of the smoke exhaust port measured by the sulfur hexafluoride sensor by the volume of the smoke exhaust port, Q α is obtained by multiplying the sulfur hexafluoride introduction concentration measured by the gas flow meter 24 of the gas supply mechanism 2 by the volume of the building.

[0047] The processor 1 used in the present application is preferably a PC, and the temperature sensor 5, the speed sensor 6, the sulfur hexafluoride sensor, the fan 9, the electromagnetic valve 23, and the gas flow meter 24 are all existing known electrical devices and can be directly purchased and used on the market, and their structures, circuits, and control principles are all existing known technologies, therefore, the structures, circuits, and control principles of the PC, the temperature sensor 5, the speed sensor 6, the sulfur hexafluoride sensor, the fan 9, the electromagnetic valve 23, and the gas flow meter 24 are not described in detail here.

[0048] Finally, it should be noted that: the above embodiments are merely the preferred embodiments of the present application to illustrate the technical solutions of the present application, rather than limit, of course, is not to limit the scope of the patent of the present application; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still be modified to the technical solutions recorded in the foregoing embodiments, or part or all of the technical features are replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, but whatever is made in the main design idea and spirit of the present application has no substantial significance of the change or polish, the technical problem solved is still consistent with the present application, and should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the patent protection scope of the present application.

Claims

1. A measurement method suitable for a building smoke exhaust efficiency measurement system, characterized in that, The measuring system comprises a processor (1), a building (4), a smoke outlet (3) arranged on the building (4), a gas feeding mechanism (2) connected to the building (4) and connected to the processor (1) for feeding tracer gas into the building (4), a temperature sensor (5), a velocity sensor (6) and a tracer gas sensor (7) arranged in the smoke outlet (3), and a combustion source (8) and a fan (9) arranged in the building (4); the processor (1) is connected to the temperature sensor (5), the velocity sensor (6), the tracer gas sensor (7) and the fan (9) respectively; The measuring method comprises the following steps: Step 1, igniting the combustion source at a typical position in the building, and simultaneously opening the gas feeding mechanism and the fan, and continuously feeding the tracer gas into the plume of the combustion source; Step 2, within 60 seconds after the combustion source is ignited, opening the smoke flue duct fan and the smoke outlet to start smoke exhaust, and opening the temperature sensor, the velocity sensor and the tracer gas sensor to measure the temperature and flow velocity of the exhaust smoke, and the concentration of the tracer gas exhausted with the exhaust smoke, until the combustion source is burned out and the gas feeding mechanism is closed; Step 3, the temperature and flow rate of the flue gas exhaust, and the concentration of the tracer gas exhausted with the flue gas are fed back to the processor, and the exhaust gas rate redundancy rate η is calculated respectively in combination with the concentration of the tracer gas input V , the convection heat removal rate η CHR , and the tracer gas exhaust rate η TG Then, the exhaust gas rate redundancy rate η V , the convection heat removal rate η CHR , and the tracer gas exhaust rate η TG are weighted to obtain the total exhaust efficiency η.

2. The measurement method suitable for a building smoke exhaust efficiency measurement system according to claim 1, characterized in that, The total exhaust smoke efficiency calculation formula is: total exhaust smoke efficiency η calculation formula is: η = α1η V + α2η CHR + α3η TG , wherein α1, α2 and α3 are weight factors, α1 is 0.2-0.3, α2 is 0.4-0.5, and α3 is 0.2-0.

4.

3. A method of measurement suitable for a building smoke exhaust efficiency measurement system according to claim 2, characterized in that, α1 is 0.3, α2 is 0.5, and α3 is 0.

2.

4. The measurement method suitable for building smoke exhaust efficiency measurement system according to claim 1, characterized in that, The exhaust smoke volume redundancy rate η V The calculation formula is: η V = (Vp-V) / V, wherein V p is the exhaust smoke fan air volume, and V is the fire smoke production volume.

5. The method for measuring the smoke exhaust efficiency of a building according to claim 1, wherein, tracer gas exhaust rate η TG The calculation formula is: η TG = Q O / Q α , wherein Q o represents the amount of tracer gas discharged by the exhaust system per unit time, and Q α represents the amount of tracer gas released to the building per unit time.

6. The method for measuring the smoke exhaust efficiency of a building according to claim 1, wherein, The gas feeding mechanism (2) comprises a gas storage tank (21) for storing the tracer gas, and a gas feeding pipe (22) connected to the gas storage tank (21) and connected to the building (4), and the gas feeding pipe (22) is provided with an electromagnetic valve (23) and a gas flow meter (24) connected to the processor (1) respectively.

7. The method for measuring the smoke exhaust efficiency of a building according to claim 1, wherein, The tracer gas is sulfur hexafluoride, and the tracer gas sensor (7) is a sulfur hexafluoride sensor.

8. The method for measuring the efficiency of a building smoke exhaust system according to claim 1, wherein, The combustion source (8) is an alcohol stove using alcohol as fuel.

9. The method for measuring the efficiency of a building smoke exhaust system according to claim 1, wherein, At least two temperature sensors (5), one velocity sensor (6) and two tracer gas sensors (7) are arranged in each smoke outlet (3).

Images