Digital system hydration heat monitoring
Digital system hydration heat monitoring At this stage, China's economy is rapidly taking off, and many large-scale civil engineering projects have been launched across the country. Such as the Three Gorges Water Conservancy Project, high-speed train lines and highways.
In such large-scale construction projects, the quality of concrete pouring is an important factor related to the survival of the project. In order to ensure the quality of concrete pouring,
Must be done: 1. At any two points of the concrete column during the maintenance period, China's economy is rapidly taking off, and many large civil engineering projects have been launched all over the country. Such as the Three Gorges Water Conservancy Project, high-speed train lines and highways.
In such large-scale construction projects, the quality of concrete pouring is an important factor related to the survival of the project. In order to ensure the quality of concrete pouring, we must:
1. The temperature difference between any two points of the concrete column during curing cannot exceed the specified value;
2. The hydration heat temperature curve for the 14 days after the concrete is poured must conform to the hydration heat temperature curve of the concrete used;
3. When pouring the bridge, the thermal expansion and contraction of the various parts of the bridge body are different after the concrete is exposed to the sun, resulting in temperature differences between the bridge deck and the web.
Temperature stress is generated, and this stress cannot exceed the safety limit value, otherwise the bearing capacity of the bridge will be affected.
In actual engineering, the dispatcher needs to know the operation status of the equipment on the construction site and the process parameters to ensure the quality of the pouring in order to make objective decisions and efficiently organize production and construction. At present, the level of hardware equipment and software in many construction site dispatch rooms is far from meeting the requirements of modern communication, production and safety management. Therefore, a monitoring system that can adapt to the requirements of large construction sites is needed to fully understand the production for commanders And equipment operation conditions to provide effective ways to achieve optimal production scheduling, ensure the smooth progress of on-site construction, improve work efficiency, and ensure construction quality.
In the monitoring of concrete hydration heat, due to the limitation of its own characteristics, the temperature monitoring system is not suitable for using traditional analog temperature sensors. The reasons are as follows:
1. Why the traditional analog temperature sensor is not suitable for the concrete hydration heat monitoring system:
The structure of a traditional temperature test system is usually:
Temperature sensor-signal conditioning-A / D conversion-collector-the temperature value of each sensor of the computer must enter the system through the above link. So there are the following disadvantages:
a) Hundreds or thousands of signal lines are needed (concrete hydration heat monitoring system has a large range and dense measuring points)
b) The analog voltage signal is easily lost during transmission, affecting system accuracy, and the transmission distance is short.
c) There are many system links and it is difficult to maintain. And the accuracy of the system is susceptible to environmental influences and difficult to guarantee.
d) expensive. 200 ~ 300 points need 100,000 ~ 200,000
2. The application of new technologies makes the system more convenient. With the development of science and technology, digital and networked sensors have become the trend of technology and the mainstream of the market. DS18B20 digitization of American DALLAS company,
The networked temperature sensor uses a unique idea to successfully resolve the contradiction between digitization, networking and cost. Make it easy to set up,
A cost-effective and reliable monitoring system is possible.
LTM-8000 digital temperature and humidity environment monitoring system adopts the advanced chip technology of American DALLAS company and combines with the scene conditions in China.
With the application of intelligent fieldbus technology, there is only digital signal transmission in the entire system, and sensors and acquisition modules can be networked.
Make the system more reliable and wiring more convenient.
The main features of the system based on digital and networked sensors:
a) With few cables, the sensors can be connected in series through the bus. Dozens of sensors use only one 3-core wire. Greatly reduces field cables and facilitates field wiring.
b) Since the sensor outputs digital signals, there is no loss of accuracy during transmission, and the system accuracy can be guaranteed.
c) There are few links in the system, and the sensor directly enters the collector. There are fewer links in the system that may fail and it is easy to maintain.
d) The use of advanced chip technology, unique concepts, and large-scale production greatly reduces system costs and improves reliability.
Introduction to digital concrete hydration heat monitoring systemThe configuration of this system is divided into the following parts:
1) Host computer:
Function: Data processing and user interface hardware requirements: Pentium 133 / 32M DRAM / 4.3G or above compatible machine or industrial computer.
Software: Optional configuration software or custom program
2) RS232 / 485 communication converter LTM-8520E, with over-voltage, over-current, surge, isolation, lightning protection
3) Field acquisition module LTM-8003E
Function: Realize the communication between two levels of communication networks. One level to the host computer RS-485 network, as a sub-station; the other level is the "first-line bus",
The Siemens analog module is used as the acquisition center, and the digital sensor on the measurement cable is used as the sub station.
Hardware function: with over-voltage, over-current, surge, isolation, lightning protection
4) Temperature sensor WZP
◎ Digital, networked temperature sensor wzp Introduction The digital temperature sensor WZP of the semiconductor company is the world's first temperature sensor that supports the "first-line bus" interface.
The unique and economical characteristics of the first-line bus make it easy for users to form sensor networks and introduce new concepts for the construction of measurement systems.
The new-generation S7200 is smaller, more economical, and more flexible.
S7200, the measurement temperature range is -55 ° C ~ + 125 ° C, the accuracy is ± 0.5 ° C, and the resolution is 0.0625 in the range of -10 ~ + 85 ° C.
The field temperature is directly transmitted in the digital mode of "first-line bus", each with its own address, which greatly reduces the number of system cables and improves the stability and anti-interference of the system. Corresponding to the traditional concept, this triode-like sensor is equivalent to the traditional one: temperature sensor + digitization + cpu + bus protocol and interface.