The routine radioactive detection of biological samples usually requires a large amount of sample concentration and enrichment, and rapid ashing of samples has become a weak link in radiochemical analysis. Based on years of experience in microwave sample preparation technology and integrating multiple innovative technologies, our company has developed a high-capacity biological sample ashing device, providing a new high-capacity rapid ashing technology for the pre-treatment of radioactive analysis samples. Applicable to various environmental protection departments, nuclear and radiation safety supervision stations, nuclear and radiation safety centers, radiation environment monitoring technology centers, nuclear facility operation units, radiation protection research institutes, nuclear industry research institutes, and nuclear science related research institutes for ashing treatment of large capacity biological samples such as grain crops, vegetables, aquatic products, meat, etc.

Patent number: ZL 2013 2 0708864. X

Execution standard: GB 5959.6-2008 (Safety Specification for Heating of Industrial Microwave Equipment)

Reference standard: GB14883.1.2016 (National Food Safety Standard - General Principles for the Inspection of Radioactive Substances in Food)

Equipment technical performance parameters:

1. Equipment name: Large capacity microwave drying carbonization ashing integrated furnace;

2. Power supply: 220V ± 10V, 50Hz ± 1Hz, overall power 7000W;

3. Equipment dimensions: 950x1600x750mm (length x height x width);

4. Sample container: can hold 10L high-performance crucible, can process 1-4Kg of material at once, can be rapidly cooled and heated at 0-1000 ℃, without cracking or powder falling;

5. Heating method: microwave and auxiliary heating combined, microwave heating and auxiliary heating work together to achieve more complete and uniform ashing;

6. Cooling method: high-speed centrifugal fan air cooling;

7. Microwave power: 0-3200W closed-loop PID power control, continuously adjustable;

8. Working hours: Able to work continuously for 24 hours;

9. Microwave leakage prevention: equipped with inductive suppressors to prevent microwave leakage, microwave leakage rate:<5mw/cm2 (national standard);

10. The door adopts a high impedance filtering and anti current structure based on a quarter cutoff wavelength of 2450MHz microwave frequency, and the microwave leakage is much lower than the limit of the national standard (5mW/cm2), which can be comparable to household microwave ovens that enter the majority of households. The electronic control design of the door latch adopts triple lock safety protection technology requirements that comply with the UL923 standard in the United States, providing users with a safe operating environment. Equipped with an internal safety locking mechanism that can automatically stop the operation of the instrument in case of unexpected situations;

11. Microwave feeding section: Microwave feeding sections are provided on both sides and behind the microwave cavity;

12. Operation mode: Drying, carbonization, and ashing are integrated, and the collected fresh samples are directly placed into a closed special 10L quartz crucible without contaminating the furnace chamber during the process; Provide 5 or more pre-treatment process schemes for radioactive detection of biological samples.

13. Equipment composition: mainly composed of microwave high-temperature system, atmosphere control system, electrical control system and other accessories.

13.1 Microwave high temperature system: mainly composed of a specially designed microwave heating large capacity crucible, microwave heating chamber, microwave source, temperature measuring thermocouple, insulation system, etc; The microwave high-temperature system enables materials to complete the three processes of drying, carbonization, and ashing in a continuous process. Among them, the dehydration and drying stage quickly completes dehydration under low temperature conditions, avoiding the effects of prolonged time and high temperature on nuclide sublimation and drift under traditional drying conditions. During the pyrolysis carbonization stage, the dry powder of the dehydrated material continues to undergo pyrolysis reaction under low oxygen conditions, and the gas is discharged until it is completely carbonized. During the ashing stage, the equipment begins to introduce air, and high-temperature carbides begin to oxidize and decompose until they are completely ashed.

13.1.1 Specially designed microwave heatable large capacity crucible: a specially customized crucible made of quartz material that can hold materials with a maximum volume of 10L;

13.1.2 The microwave heating chamber is mainly made of stainless steel 304 welded together, and microwave sources are installed on the periphery, sides, and rear of the chamber;

13.1.3 The microwave source mainly consists of a magnetron, a high-voltage transformer, a high-voltage rectifier circuit, as well as overcurrent protection and abnormal temperature protection;

13.1.4 Temperature measurement system: Thermocouple temperature measurement, working temperature 0~1000 ℃, temperature measurement accuracy ± 1 ℃, maximum temperature 1200 ℃,

13.1.5 The insulation system is composed of materials with good insulation effect and low dielectric constant, designed as three-layer insulation;

13.2 Atmosphere control system: Automatic control is adopted to automatically control the intake and exhaust of air during the experimental process according to the experimental procedure. During the dehydration and drying stage, the moisture in the material is discharged from the equipment; During the pyrolysis carbonization stage, control the intake air to keep the material in a lean oxygen environment; During the ashing stage, control the introduction of air to initiate the oxidation and decomposition of high-temperature carbides;

13.3 adopts PLC color touch screen intelligent control, which can store 50 methods, each method can set 5 temperature rise programs, and the operating parameters can be modified on the control screen according to different working conditions. The experimental data is recorded throughout the process, equipped with a standard USB interface, and the experimental data can be exported;

13.3.1 Data acquisition system: Various data are collected and transmitted to the controller, which calculates and issues instructions based on the data. During the microwave heating process, thermocouple data is collected, and the PLC can manually and automatically control it through this data acquisition, facilitating process interpretation;

13.3.2 Thermocouple Sensor: Thermocouple temperature measurement data is transmitted to the controller. Due to the fact that some nuclides can sublime at low temperatures, precise temperature control is required, and the ashing temperature of the entire process flow needs to be controlled to prevent nuclide sublimation and overflow;

13.3.3 Improve independent control and protection circuits to ensure that the use of each component does not interfere with each other;

13.3.4 Adopt a temperature controller to protect the core components of the microwave source and extend its service life;

13.3.5 Adopt overcurrent protector to prevent excessive current;

13.3.6 Adopt the most advanced multi-source and multi port broadband feeding to ensure heat balance inside the box;

14. The design and installation of the equipment generally consider the requirements of safety, stability, reliability, hygiene, ease of operation, and maintenance;