阅读说明：本技术 一种常温下电缆竖井防火封堵密封性检测办法 (Method for detecting sealing performance of fireproof plugging of cable shaft at normal temperature ) 是由 刘勇 李武 邓雨薇 于 2021-01-13 设计创作，主要内容包括：一种常温下电缆竖井防火封堵密封性检测办法,包括构建电缆竖井火灾模型,通过设定的参数模拟处标准的气体扩散速度临界值,在待测楼层内释放一定浓度的CO2气体,CO2检测分机检测所在楼层的CO2浓度并发送至监控主机进行记录,生产CO2浓度随时间变化的曲线,通过分析软件分析数据判定是否合格。解决了现有防火封堵标准不能满足对电缆竖井防火封堵密闭性检测的要求,提出基于CO2扩散浓度检测的电缆竖井防火封堵密封性检测方法,用于检测判断电缆竖井防火封堵的密封性能是否达标。(A method for detecting the fire blocking tightness of a cable shaft at normal temperature comprises the steps of constructing a cable shaft fire model, releasing CO2 gas with a certain concentration in a floor to be detected through a set parameter simulation standard gas diffusion speed critical value, detecting the CO2 concentration of the floor where an extension set is located by a CO2 detection extension set, sending the CO2 concentration to a monitoring host for recording, producing a curve of the CO2 concentration changing along with time, and analyzing data through analysis software to judge whether the fire blocking tightness is qualified or not. The method solves the problem that the existing fireproof plugging standard cannot meet the requirement for detecting the fireproof plugging tightness of the cable shaft, and provides a method for detecting the fireproof plugging tightness of the cable shaft based on CO2 diffusion concentration detection, which is used for detecting and judging whether the sealing performance of the fireproof plugging of the cable shaft reaches the standard or not.)

1. The method for detecting the sealing performance of the fireproof plugging of the cable shaft at normal temperature is characterized by comprising the following steps of:

step one, constructing a cable shaft fire model, and selecting CO under constraint conditions₂Establishing a theoretical model and experimental simulation to obtain a CO2 concentration diffusion model at high temperature as a main standard for detecting the sealing performance of the fireproof plugging, deriving the model by experimental simulation and simulation at normal temperature to obtain a CO2 concentration diffusion model at normal temperature, and obtaining the fireproof plugging at normal temperature according to the CO2 concentration diffusion rule at normal temperatureA tightness detection standard;

measuring the test temperature, the space size and the size of the cable shaft of the detection floor, calculating the effective diffusion area, setting a standard concentration difference, substituting the measurement parameters and the calculation parameters into the CO2 concentration diffusion model at the normal temperature, and obtaining a corresponding diffusion speed value which is firstly stored in a lookup table to obtain a diffusion standard rule under the current condition;

step two, arranging CO2 detection extensions in the floor to be detected and cable shafts of upper and lower floors adjacent to the floor to be detected, arranging a monitoring host outside the floor, and connecting the monitoring host with each CO2 detection extension through wireless communication;

step three, releasing CO2 to a certain concentration in the floor to be detected through a gas cylinder;

detecting the concentration of CO2 in the floor where the extension set is detected through CO2, sending data to a monitoring host, and recording all measured data in real time by the monitoring host;

and step five, analyzing and processing the received data by the monitoring host, displaying and storing the data, recording a curve of the current CO2 concentration along with the change of time, and analyzing the data by analysis software to judge that the data is qualified enough.

2. The forest information extraction system based on the object-oriented remote sensing image as claimed in claim 1, wherein in the first step, the specific process of constructing the fire model of the cable shaft is as follows: the method comprises the steps of carrying out simplified model by setting the current size of the cable shaft, setting a comparative size test, carrying out high-temperature air tightness simulation in a non-airtight environment, and selecting the provided standard model for fireproof plugging of the simplified cable shaftk-εRenormalization in modelsk −εAnd carrying out theoretical calculation on the model by using a turbulence model, and establishing a cable shaft tightness detection model.

3. The forest information extraction system based on object-oriented remote sensing images as claimed in claim 2, wherein in the fifth step, the forest information extraction system is based on CO actually measured according to the floor to be measured₂Change in concentrationCurves and actually measured CO of upper and lower floors₂CO calculation from concentration Change Curve₂And comparing the gas diffusion speed with a set threshold value of the theoretical calculation critical value under the current conditions in the step two, and determining that the gas diffusion speed is not qualified if the gas diffusion speed is higher than the set threshold value.

4. The forest information extraction system based on object-oriented remote sensing images as claimed in claim 3, wherein the CO is a carbon monoxide (CO)₂The set threshold value of the gas diffusion rate criterion was set to 95% of the critical value.

5. The forest information extraction system based on object-oriented remote sensing images as claimed in claim 4, wherein the standard concentration difference set in the second step is within the threshold value of 5000-.

6. The forest information extraction system based on object-oriented remote sensing images as claimed in claim 5, wherein the monitoring host records CO transmitted by each CO2 detection branch machine₂And when the concentration is detected, reducing the error by adopting a section average value method.

7. The forest information extraction system based on the object-oriented remote sensing image as claimed in claim 1, wherein the sampling interval of the CO2 detection branch is not more than 6S.

Technical Field

The invention relates to the field of electric power safety detection equipment and accessory equipment thereof, in particular to a method for detecting the sealing performance of a fireproof plugging of a cable shaft at normal temperature.

Background

The number of high-rise buildings, super high-rise buildings and large buildings in cities is increasing, electrical vertical shafts such as staircases, elevator rooms and pipe shafts in the high-rise buildings are easy to generate chimney effect once a fire breaks out, and the spreading speed of fire rapidly increases once the electrical vertical shafts generate the chimney effect in the fire, so that the electrical vertical shafts finally become a rapid passage for spreading the fire. Therefore, after the strong and weak electric lines in the cable shaft are deployed, fireproof plugging must be carried out and the fireproof standard must be met, so that the cable shaft is prevented from being a fire propagation channel, and the fire risk is reduced. However, no corresponding fireproof plugging detection method standard exists in the market at present, and a system and a method for detecting the fireproof plugging sealing performance of the cable shaft based on CO2 detection are also absent, so that whether the sealing performance of the fireproof plugging of the cable shaft reaches the standard or not is detected and judged.

In the prior art, equipment for detecting the sealing performance of the fireproof plug of the cable shaft is provided, and Chinese patent document CN 111024320A describes a detector for the sealing performance of the fireproof plug of the cable shaft, which comprises a main detector and an auxiliary detector, wherein the main detector comprises a gas cylinder and a first gas concentration sensor, an electromagnetic valve is arranged on the gas cylinder and used for opening or closing the gas cylinder; the auxiliary detector comprises a second gas concentration sensor, and the main detector and the auxiliary detector are respectively arranged in adjacent floors in the cable shaft; the device can detect the gas concentration of the plugging test, but a system method for judging the plugging prevention sealing performance scientifically and accurately does not exist.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for detecting the sealing performance of the fireproof plugging of the cable shaft at normal temperature, which can systematically perform comparable simulation and test detection on the sealing performance of the fireproof plugging of the cable shaft and judge whether the plugging effect reaches the standard or not.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a method for detecting the sealing performance of a fireproof plugging of a cable shaft at normal temperature comprises the following steps:

step one, constructing a cable shaft fire model, and selecting CO under constraint conditions₂Establishing a theoretical model and experimental simulation to obtain a CO2 concentration diffusion model at high temperature as a main standard for detecting the sealing performance of the fireproof plugging, deriving the model by experimental simulation and simulation at normal temperature to obtain a CO2 concentration diffusion model at normal temperature, and obtaining the fireproof plugging at normal temperature according to the CO2 concentration diffusion rule at normal temperatureA tightness detection standard;

measuring the test temperature, the space size and the size of the cable shaft of the detection floor, calculating the effective diffusion area, setting a standard concentration difference, substituting the measurement parameters and the calculation parameters into the CO2 concentration diffusion model at the normal temperature, and obtaining a corresponding diffusion speed value which is firstly stored in a lookup table to obtain a diffusion standard rule under the current condition;

step two, arranging CO in the cable shaft of the floor to be detected and the adjacent upper and lower floors of the floor to be detected₂The detection extension set is provided with a monitoring host outside the floor, the monitoring host and each CO₂The detection extension set is connected through wireless communication;

step three, releasing CO through the gas cylinder in the floor to be detected₂To a certain concentration;

step four, passing CO₂Detect extension and detect CO in floor₂Concentration, and sending the data to a monitoring host computer, and recording all measurement data in real time by the monitoring host computer;

step five, the monitoring host computer analyzes and processes the received data, displays and stores the data and records the current CO₂The concentration profile over time was then judged to be adequate by analysis of the data by analytical software.

In the first step, the specific process of constructing the cable shaft fire disaster model comprises the following steps: the method comprises the steps of setting the size of a current cable shaft, carrying out a simplified model, setting a comparative size test, carrying out high-temperature air tightness simulation under a non-airtight environment, selecting a renormalized k-epsilon model in a k-epsilon model for carrying out theoretical calculation on a turbulence model for the proposed simplified cable shaft fireproof plugging standard model, and establishing a cable shaft tightness detection model.

In the fifth step, the actual measurement is carried out according to the CO measured according to the floor to be measured₂Concentration change curve and actually measured CO of upper and lower floors₂CO calculation from concentration Change Curve₂And comparing the gas diffusion speed with a set threshold value of the theoretical calculation critical value under the current conditions in the step two, and determining that the gas diffusion speed is not qualified if the gas diffusion speed is higher than the set threshold value.

CO as described above₂The set threshold value of the gas diffusion rate criterion was set to 95% of the critical value.

The monitoring host records each CO₂Detecting CO transmitted by extension₂And when the concentration is detected, reducing the error by adopting a section average value method.

CO as described above₂The sampling interval of the detection extension is not more than 6S.

The method for detecting the sealing performance of the fireproof blocking of the cable shaft at normal temperature comprises the steps that a detection extension is connected with a monitoring host through a WiFi network, CO2 is released to a certain concentration through a gas cylinder at a floor to be detected, the concentration of carbon dioxide in the floor where the detection extension 2 is located is detected through a CO2, and real-time acquired data are obtained; the monitoring host machine processes and analyzes the received data, displays and stores the data, records the change curve of the CO2 concentration of the current layer along with the time, and then analyzes the data through analysis software to judge whether the data is qualified. The method comprises the steps of providing a CO2 change curve through data analysis, quantitatively measuring and calculating the gas leakage degree if plugging is unqualified and gas leakage is serious, accordingly providing a quantitative detection result of the fireproof plugging tightness of the cable shaft, and judging whether construction quality is qualified or not according to engineering design requirements.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

FIG. 1 is a schematic view of the working flow of the detection method of the present invention;

fig. 2 is a layout diagram of the system device.

Detailed Description

As shown in fig. 1-2, a method for detecting the sealing performance of the fireproof plugging of the cable shaft at normal temperature comprises the following steps:

step one, constructing a cable shaft fire model, and selecting CO under constraint conditions₂Sealing performance as fireproof plugging detectionEstablishing a theoretical model and experimental simulation to obtain a CO2 concentration diffusion model at high temperature, deriving the model by experimental simulation and simulation at normal temperature to obtain a CO2 concentration diffusion model at normal temperature, and obtaining a fireproof plugging sealing performance detection standard at normal temperature according to a CO2 concentration diffusion rule at normal temperature;

measuring the test temperature, the space size and the size of the cable shaft of the detection floor, calculating the effective diffusion area, setting a standard concentration difference, substituting the measurement parameters and the calculation parameters into the CO2 concentration diffusion model at the normal temperature, and obtaining a corresponding diffusion speed value which is firstly stored in a lookup table to obtain a diffusion standard rule under the current condition;

step two, arranging CO in the cable shaft of the floor to be detected and the adjacent upper and lower floors of the floor to be detected₂The detection extension set is provided with a monitoring host outside the floor, the monitoring host and each CO₂The detection extension set is connected through wireless communication;

step three, releasing CO through the gas cylinder in the floor to be detected₂To a certain concentration;

step four, passing CO₂Detect extension and detect CO in floor₂Concentration, and sending the data to a monitoring host computer, and recording all measurement data in real time by the monitoring host computer;

step five, the monitoring host computer analyzes and processes the received data, displays and stores the data and records the current CO₂The concentration profile over time was then judged to be adequate by analysis of the data by analytical software.

The carbon dioxide gas is colorless and nontoxic, has stable molecular structure, does not generate chemical reaction under the conditions of high temperature and the like, does not pollute the environment, and can be used as a detection medium for the fireproof plugging detection of the cable shaft. Although the cable shaft is not a sealed container, the quality detection of the fireproof plugging can be still performed by measuring the leakage concentration of the carbon dioxide gas on the upper floor and the lower floor, and the difference is that the relationship between the size of the cable shaft, the volume (concentration) of released carbon dioxide and the change size and change speed of the concentration of the carbon dioxide on the upper floor and the lower floor needs to be established.

In the first step, the specific process of constructing the cable shaft fire disaster model comprises the following steps: the method comprises the steps of setting the size of a current cable shaft, carrying out a simplified model, setting a comparative size test, carrying out high-temperature air tightness simulation under a non-airtight environment, selecting a renormalized k-epsilon model in a k-epsilon model for carrying out theoretical calculation on a turbulence model for the proposed simplified cable shaft fireproof plugging standard model, and establishing a cable shaft tightness detection model.

The gas flow problem of the high-rise building cable shaft in the non-closed environment is suitable for theoretical calculation by adopting a gas flow basic theoretical model-turbulence model, the method for analyzing the smoke flow simulation of the building atrium by using the gas flow model and a numerical calculation method is proposed in 1998, a second-order standard k-epsilon model is used at the time, the calculation precision is relatively low, the current turbulence numerical simulation method can be divided into three types, a Reynolds time average simulation method, a scale analysis simulation method and a direct numerical simulation method, and based on the analysis, the smoke simulation model of the cable shaft in fire is simple, and a renormalized k-epsilon model (namely an RNG k-epsilon model) which is relatively simple in calculation and high in precision is selected from the k-epsilon model. After a simplified cable shaft fireproof blocking standard model (1.5m × 3m) is subjected to grid division, popular FLUENT turbulence model calculation software (core parameters are empirical parameters due to a differential equation with a complex relation among turbulence viscosity mu, turbulence energy k and dissipation rate epsilon) is adopted to obtain a calculation conclusion: under the condition of non-closed space turbulence at 342 ℃, the critical value of the total area of the air leakage gap with the chimney effect is 0.0016m²On the left and right sides, the ratio of the total area of the air leakage gap to the bottom area of the model is about 0.071%.

In the fifth step, the actual measurement is carried out according to the CO measured according to the floor to be measured₂Concentration change curve and actually measured CO of upper and lower floors₂CO calculation from concentration Change Curve₂Comparing the gas diffusion speed with a set threshold value of the theoretical calculation critical value under the current condition in the step two, and determining that the gas diffusion speed is unqualified if the gas diffusion speed is higher than the set threshold value;

in the fifth step, in order to intuitively simulate the situation of the cable shaft in Fire, Fire dynamic simulator software is adopted to simulate and calculate the Fire condition of the cable shaft, the flame temperature is set to be 342 ℃ of the ignition point temperature of Polyethylene (PE), and a preliminary conclusion can be obtained through simulation analysis: under the condition of micro cracks, the critical value of the total area of the gaps of the fireproof plugging, which generates the chimney effect, is basically in direct proportion to the bottom area, and the chimney effect is ensured to occur when the critical value exceeds 0.66 percent of the bottom area.

And because the concentration of the CO2 released by the floor to be detected is difficult to accurately control, the method for judging whether the plugging quality is qualified by adopting a fixed standard is not feasible, the CO2 gas diffusion speed is calculated according to the actually measured CO2 concentration change curve of the floor to be detected and the actually measured CO2 concentration change curves of the upper floor and the lower floor, the value is compared with the set threshold value of the theoretical calculation critical value under the current condition in the step two, and the floor higher than the set threshold value is judged to be unqualified.

The diffusion velocity value is a function of temperature, space size, gas concentration difference and effective diffusion area, and needs to be calculated through partial differential equation of a theoretical model, the velocity temporarily calculated in the actual detection process cannot keep up with the actual requirement, in order to solve the problem, the corresponding diffusion velocity value can be calculated in advance in the modes of setting the detection space size (limited common used), setting temperature (common air temperature), setting concentration difference and effective diffusion area (theoretical calculation threshold) and stored in a lookup table, and the diffusion under the current condition can be calculated through the interpolation mode under other special conditions not listed in the table, wherein the interpolation formula is as follows:

wherein t1 and t2 are two upper and lower temperature values (t1< t < t2) which are stored in the table and are closest to t with the current temperature, c1 and c2 are two upper and lower maximum concentration values (c1< c < c2) which are stored in the table and are closest to c with the current maximum concentration, and the interpolation error is calculated to be small and basically negligible.

CO as described above₂The set threshold value of the gas diffusion rate criterion was set to 95% of the critical value.

It should be noted that the cable shaft size, the temperature condition, and the CO2 concentration value released by the middle layer during each detection are different, the detection result needs to be queried according to a provided quick look-up table, and interpolation calculation is also needed if the table does not exist, so as to obtain a determination threshold for determining whether the detection is qualified. The position of the auxiliary detector is generally placed in the middle of a house, and the comparison is generally carried out by 95% of a threshold value when a report is generated, so that the detection result is stricter.

The monitoring host records each CO₂Detecting CO transmitted by extension₂And when the concentration is detected, reducing the error by adopting a section average value method.

CO as described above₂Detecting that the sampling interval of the extension is not more than 6S, recording all measurement data in real time, processing and analyzing the received data, displaying and storing, and recording CO of the current layer₂And (3) a curve of the concentration along with the change of time, and analyzing the data by analysis software to judge whether the concentration is qualified.

After detection is finished, data of monitoring host equipment of the cable shaft fireproof plugging tightness detection system can be temporarily reserved, the system collects CO2 concentration change within set time and stores the change to the local, and synchronous attempt is sent to a tablet personal computer in a wireless mode; at the moment, the user can generate an EXCEL concentration report and a WORD document brief according to the current data to store the data for later analysis or other purposes, and the brief and the report can be locally browsed through the mobile tablet after being generated, so that the data can be conveniently consulted and transmitted to other equipment such as a personal computer and the like in real time.