Application of carbon dioxide gas detector in grain storage engineering
The application of carbon dioxide gas detector in grain storage engineering is introduced in this article. The application of the automatic monitoring system for CO2 concentration in grain warehouses in grain storage engineering is described. The use of an infrared gas analyzer to monitor the CO2 concentration in grain warehouses has high accuracy, reliable performance, and can be continuously measured online for a long time. This provides an effective way for controlling CO2 concentration in controlled atmosphere grain depots. The CO2 automatic monitoring system adopts advanced detection and automatic control technology to achieve fully automatic measurement and data processing of CO2 concentration in grain warehouses.
This system is the key to achieving gas control technology and ensuring process concentration. Its main functions include real-time automatic collection, conversion, and transmission of CO2 data in grain warehouses, data display, printing, data management (including data recording, data analysis and processing, alarm prompts, reserved data communication, etc.), and switching between manual and automatic operations. It can achieve open setting and adjustment of system parameters for easy upgrading and updating Optimize settings.
The system principle is as follows: Keywords: grain storage, CO2 controlled grain storage, infrared gas analyzer 1. Overview: Grain storage engineering is a system engineering that integrates multiple disciplines such as agriculture, biology, architecture, environmental protection, chemical engineering, instrumentation, computer technology, etc. With the rapid development of modernization construction in China, the construction of "green granaries" is an important topic in the current grain storage industry. In the process of grain storage, in order to ensure the quality and quality of stored grain, it is necessary to prevent the damage of stored grain pests and molds in the grain.
For a long time, chemical agents such as Phosphine and ethylene oxide have been used to fumigate grains to kill pests in China. The research on the technology of carbon dioxide (CO2) modified atmosphere storage of grain had been tested for killing insects as early as 1917. After the 1940s, its development was limited by the use of cheap pesticides. Later, problems such as pesticide residues, environmental pollution, damage to the ecological environment, and the increase of insect resistance have attracted more and more attention. The demand for natural green food has brought the CO2 modified atmosphere storage of grain back to people's attention. The United States, Japan, Russia Developed countries such as Australia have gradually reduced the use of chemical agents in grain storage and are moving towards ecological grain storage with low temperature, controlled atmosphere, and comprehensive physical and biological control. They have conducted extensive research and experiments on CO2 controlled atmosphere storage technology and successfully applied it, establishing commercial usage standards.
After testing, its engineering construction has reached an excellent level, at the highest level in China and at an advanced level internationally. In the design of the CO2 controlled grain depot at Chengdu Grain Science and Technology Institute, According to the "six modernizations" and "three high and three low" standards in the goals and requirements of China's grain storage development (namely, modernization of equipment, networking of information, scientific Management science, intensive operation, instrumentalization of monitoring and high-quality talents; high-quality, high efficiency, high nutrition, low consumption, low pollution and low cost), Mianyang CO2 CA grain storage demonstration depot was scientifically designed. For the important link of automatic monitoring of CO2 concentration in grain warehouses, which is an important part of the gas control project, based on successful international experience, the GXH-3010D (process type) active non dispersive infrared CO2 analyzer that can work continuously was selected. After nearly a year of long-term operation in the gas control project of directly affiliated warehouses in Mianyang, it has been successfully applied and gained practical experience. 2. Introduction to CO2 gas control warehouses adopts CO2 gas control grain storage technology, It refers to the method of filling CO2 gas into the warehouse with good airtight performance to change the composition of gas components in the granary, destroy the ecological environment of pests and molds, inhibit the physiological respiration of grain, prevent insects, kill insects, inhibit bacteria, and delay the aging of grain quality, so as to realize the purpose of non pharmaceutical, economic, safe, environmental protection, and fresh-keeping grain storage.
In the construction of the CO2 controlled grain storage project, a large-scale gas supply and distribution system has been adopted for centralized gas supply in the grain depot, and an automatic monitoring system for CO2 concentration in the grain depot has been adopted. Its main facilities include CO2 gas supply system, CO2 automatic monitoring system, intelligent ventilation control system, warehouse * * device, backpack oxygen respirator, etc. As shown in the following figure: Schematic diagram of the CO2 gas control system process flow, where the CO2 automatic monitoring system uses advanced detection and automatic control technology to achieve fully automatic measurement and data processing of CO2 concentration in grain warehouses.
This system is the key to achieving gas control technology and ensuring process concentration. Its main functions include real-time automatic collection, conversion, and transmission of CO2 data in grain warehouses, data display, printing, data management (including data recording, data analysis and processing, alarm prompts, reserved data communication, etc.), and switching between manual and automatic operations. It can achieve open setting and adjustment of system parameters for easy upgrading and updating Optimize settings. The system schematic diagram is as follows: 3. The infrared CO2 analyzer and gas filtering related technology The CO2 concentration automatic monitoring system of the CO2 gas storage mainly consists of three parts: sampling system, infrared CO2 analyzer, and computer remote intelligent control. The performance of the infrared CO2 analyzer plays a crucial role in the technical level of the entire monitoring system.
Due to the particularity of CO2 controlled atmosphere storage, it is required to measure CO2 in a wide range of 0-100% CO2 with a resolution of 0.1% and good reproducibility. Each working cycle of the controlled atmosphere storage is about 1 month, so the long-term stability of the instrument is required to achieve weekly drift of less than ± 2%. In order to achieve fast response time, it is necessary to install a small air pump inside the instrument to achieve negative pressure active sampling. An instrument needs to perform cyclic sampling on multiple sampling points in the warehouse, with the farthest sampling point having a pipeline length of several tens of meters. Therefore, a large flow air pump must be equipped in the sampling system and remotely controlled by a computer to switch the sampling points and the switch status between the instrument and the air pump. The concentration value output by the instrument adjusts the CO2 concentration in the warehouse to achieve closed-loop control. The infrared gas analyzer can analyze the measured gas based on the selective absorption of heteroatomic molecules in the near-infrared region.
