Composite pipe gallery

In order to solve the urban diseases such as "pull link" and "urban waterlogging" that often appeared in the past, the state has vigorously promoted the construction of comprehensive pipe corridors. On June 1, 2015, the new national standard "Technical Specification for Urban Integrated pipe Corridor Engineering" GB50838-2015 was formally implemented, and the new specification requires the implementation of monitoring of fire protection, environment, security, pipeline operation and other aspects of the integrated pipe corridor. Under the wave of the state vigorously promoting the construction of pipe corridors, many sensing equipment manufacturers and intelligent monitoring engineering contractors have heard the wind and entered the field of pipe corridor monitoring.

Integrated pipe gallery is an underground closed space, once a fire occurs, it will quickly consume the oxygen inside the pipe gallery and produce a large number of harmful gases, when methane, carbon monoxide and other dangerous gases reach a certain concentration, it can also cause an explosion. What is more serious is that the internal environment of the pipeline corridor is very bad when a disaster occurs, and it is very difficult to repair it, which will also cause personal safety threats to the repair personnel.

During the transmission process of heating pipeline and crude oil pipeline, the fluid temperature in the pipeline will be significantly different from the temperature of the surrounding environment. When the pipeline leaks, the temperature change becomes important information. According to the temperature change along the pipeline, it is possible to determine whether the pipeline leaks and locate the leak point.

Compared with traditional monitoring methods, distributed fiber optic temperature sensor pipeline leak monitoring system has the following advantages:

① Using a core optical fiber, you can complete the detection and signal transmission, all Settings are completed in the terminal, the system is simple and reliable. The traditional temperature sensor needs to be covered with electronic sensors in the tube corridor, and the sensor needs to be connected by the control circuit, which has a complex structure.

The optical fiber has a long life, up to 30 years, the monitoring distance is long (up to 30 kilometers), the traditional electronic sensor has a short life, the need to configure a large number of spare parts, and the maintenance workload is large.

③ The detection and transmission components of the optical fiber sensing system are passive optical devices, no external radiation, and anti-electromagnetic, radio frequency, lightning, radar and other effects; At the same time, it is resistant to corrosion and can operate in harsh environments that traditional sensors cannot adapt to.

④ High measurement accuracy and resolution, temperature measurement accuracy of ±1℃; Spatial resolution of up to 1 meter, equivalent to 1 sensor per meter, enables real-time monitoring of the spread of leaks (fires) through the temperature curve.

⑤ The host is placed in the control room, and the detection cable is laid in the underground pipe gallery along the location that needs to be monitored, which is simple to lay and low to maintain.

⑥ With its own diagnostic function, the cable has fault self-diagnosis and self-positioning function.

Distributed optical fiber temperature sensing technology can be applied to the following aspects of underground integrated pipe corridors:

1. Heating pipeline, oil pipeline leakage monitoring: After the leakage of the pipeline in the integrated pipe gallery, the fluid temperature is much higher than the ambient temperature, and the ambient temperature of the leak point will rise.

2. Power cable current leakage monitoring: When the power cable current leaks in the integrated pipe gallery, the temperature of the leakage point will rise.

(3) Leakage monitoring of natural gas pipelines: Natural gas pipelines are mostly low-temperature and compressed after transmission, and pipeline leakage will lead to a decline in the temperature around the leak point.

④. Fire forecasting alarm monitoring: The current leakage of the power cable in the integrated pipe corridor is very easy to cause fire, and when the fire occurs, there is a large amount of heat generation process. The system is sensitive to heat, and the temperature change before the heat accumulation reaches the ignition point can also make a very accurate judgment, accurately locate the accident point, and give the accurate temperature of the accident point, which has a strong role in early warning.

After the fire, the traditional sensor is easy to damage, and the alarm system fails after the power failure. The optical fiber sensing system uses optical cable as a sensor, as long as the optical cable is not damaged, it can always work, and the monitoring center of continuous data transmission can use the system to observe the spread of fire in real time; At the same time, it is also easy to restore the fire accident, find out the fire point and spread.

The system is divided into three levels: the central management level, the sub-control station collection level and the front-end acquisition control level.

1) Monitor the management of the center

The real-time monitoring and centralized management of the operating status of the pipeline can be realized through the real-time collection of the temperature of the pipeline heating pipeline, the liquid level of the collecting well and the status of the pump switch, methane content, video image information, etc., and the alarm information can be issued when the anomaly occurs, and the professional management personnel can dispatch and command.

2) Collection layer of sub-control center

The distributed optical fiber temperature sensing host is configured in the sub-control center to realize the processing of optical fiber temperature measurement and leakage detection of the heating pipeline under the administration of the pipe trench, and the information is transmitted to the monitoring center in real time to meet the needs of the heating pipeline leakage monitoring.

3) Integrated trench front end acquisition control layer

The temperature measuring optical fiber sensor is laid in the pipe trench, and the detection results are transmitted to the DTS distributed optical fiber temperature sensor host in the sub-control center. The sensor host analyzes and processes the collected signals in real time to realize the monitoring work of the heating pipeline. Sensor equipment such as cameras and methane sensors are configured in each area of the pipe corridor, and information is collected by the sub-control center to the monitoring center through a transmission link.

For temperature monitoring of cables of 10KV or below, S-type temperature-sensing optical cables can be used. Under normal circumstances, the same layer of cables can be laid using one optical cable. The S-type cable can save the cable usage while ensuring the effective protection area.

When a fire or high temperature hazard occurs at the cable, the distributed optical fiber linear temperature fire detector can provide timely alarm, thereby preventing or reducing the damage caused by fire accidents. The system can also upload the alarm information and temperature information to the fire alarm host for comprehensive management.

For the connection of the power cable, the cable needs to be wound to provide better monitoring and protection, as shown in the figure below.

Through device linkage, the status information can be used to control the operation of other devices, so as to complete automatic control and unattended work.

For power cables 110KV and above, temperature monitoring should be carried out for each cable. In the application, the temperature sensing cable (diameter of about 3mm) is generally laid closely above the cable, as shown in the following figure.

For power cables, the distributed optical fiber temperature measurement system can detect the temperature of the cable surface, so as to monitor the operating status of the cable, and trigger the system alarm when the cable temperature is abnormal

Optical fiber temperature measurement fire detection system is composed of optical fiber temperature measurement host and detection cable. The system monitors the ambient temperature of the integrated pipe corridor in real time, and the optical fiber temperature measuring host displays the temperature distribution curve of the current pipe corridor, which is quite intuitive. When the temperature of the pipe corridor reaches the pre-set threshold, the system will automatically issue an audible and visual alarm, and will send an alarm contact closure signal to the monitoring center.