Zero leakage vacuum high-efficiency thermal energy recovery device
1、 Zero leakage vacuum thermal energy recovery device technology and working principle
(1) Zero leakage vacuum thermal energy recovery device is a new type of heat transfer element, which should be called a "closed two-phase heat transfer system" according to a more precise definition. It is a device that relies on the phase change of the fluid inside (liquid to vapor and vapor to liquid) to transfer heat in a closed system that has been evacuated. In recent years, zero leakage vacuum thermal energy recovery device technology has developed rapidly. Due to its advantages of fast heat transfer speed, high thermal efficiency, and low operation and maintenance costs, it has been widely used in various fields of waste heat recovery.
(2) The Heat Transfer Principle of Zero Leakage Vacuum Thermal Energy Recovery Device
A closed tube shell is evacuated and filled with a certain proportion of liquid working medium (working fluid) inside, which constitutes a zero leakage vacuum thermal energy recovery device. The zero leakage vacuum heat recovery device placed in the heat source section is called the evaporation section (hot end), and placed in the cooling section is called the condensation section (cold end). When the evaporation section absorbs heat and transfers it to the working fluid, the working fluid absorbs heat and changes from liquid to vapor, undergoing a phase change and absorbing the latent heat of vaporization. Under the pressure difference inside the tube, the vapor carries latent heat and flows from the evaporation section to the condensation section, transferring the heat to the cold fluid outside the tube and releasing the latent heat of condensation. The working fluid inside the tube condenses from the vapor into a liquid, and under the action of gravity, it returns to the evaporation section to continue absorbing heat and vaporizing. This cycle repeats itself, continuously transferring heat from the hot fluid to the cold fluid.
(a) Axial heat transfer recovery device heat transfer element (b) Radial heat energy recovery device heat transfer element
(3) Characteristics of Zero Leakage Vacuum Thermal Energy Recovery Device
① The thermal conductivity rate of metal and non-metal materials themselves depends on the thermal conductivity coefficient and temperature gradient of the material, and the cross-sectional area orthogonal to the temperature gradient. Taking silver metal as an example, its value is around 415W/m.K. After measurement, the thermal conductivity of the zero leakage vacuum heat recovery device is several hundred to thousands of times that of silver. Therefore, the zero leakage vacuum heat recovery device is called a superconductor.
② Due to the fact that the heat transfer process inside the zero leakage vacuum heat recovery device is a phase change process and the purity of the working fluid is high, the steam temperature inside the zero leakage vacuum heat recovery device is basically kept constant. After measurement, the temperature difference between the two ends of the zero leakage vacuum heat recovery device does not exceed 5 ℃. Compared with other heat transfer components, the zero leakage vacuum heat recovery device has good isothermal performance.
③ The temperature range that the zero leakage vacuum heat recovery device can adapt to is related to the specific structure of the zero leakage vacuum heat recovery device, the working fluid used, and the ambient working temperature of the zero leakage vacuum heat recovery device. At present, the temperature range that zero leakage vacuum heat recovery devices can adapt to is generally -200 ℃ to 2000 ℃, which is also difficult for other heat transfer components to achieve.
④ Two types of heat exchange media are exchanged through a zero leakage vacuum heat recovery device, separated by a tube plate in the middle, and the heat exchange media flow through their respective channels. Even if a few zero leakage vacuum heat recovery devices are damaged during operation, it will not cause mixing of the two heat exchange media, and there is no need to stop the machine to seal the leak. Therefore, zero leakage vacuum thermal energy recovery equipment has the advantages of long service life, safety and reliability.
⑤ Due to the fact that each zero leakage vacuum heat recovery device is an independent heat exchange element, regardless of its size or length, each zero leakage vacuum heat recovery device can be easily disassembled and replaced, with strong performance.
2、 Structure and principle of zero leakage vacuum thermal energy recovery device and waste heat recovery device
The zero leakage vacuum heat recovery device and waste heat recovery device mainly consist of two parts: the zero leakage vacuum heat recovery device water heater and the zero leakage vacuum heat recovery device evaporator. The zero leakage vacuum heat recovery device is radially welded onto the inner cylinder, and the heat exchanged water, steam, and flue gas all pass through the outside of the pipe. The zero leakage vacuum heat recovery device adopts longitudinal finned tubes and forked rows. By using a zero leakage vacuum thermal energy recovery device, heat transfer between flue gas and water is completed, generating saturated steam. This structural form is not prone to dust accumulation.
Schematic diagram of economizer tube bundle structure
Design drawing of economizer tube bundle for thermal energy recovery device
3、 Special purpose
Features: Large scale installation, long-distance heat transfer
4、 Process plan
1. Zero leakage vacuum thermal energy recovery device for thermal power plants, economizer
Industrial process diagram of zero leakage vacuum heat recovery device heat exchanger applied to thermal power plants
2. Zero leakage vacuum heat recovery device heat exchanger for desulfurization flue gas in coking plant
In coking production, a large amount of exhaust gas is generated after the combustion of coke oven gas, mainly including SO2, NOX, and smoke, which is one of the industries with serious pollution. With the gradual introduction of emission standards for this industry, many coking plants have successively added energy-saving and emission reduction projects such as desulfurization, denitrification, and flue gas waste heat recovery.
This type of project generally extracts the 250-300 ℃ waste gas generated by coking from the underground flue and sends it to the denitrification reactor for low-temperature denitrification at a reaction temperature of 250-300 ℃. After denitrification, the flue gas is sent to the waste heat recovery device to generate pressure saturated steam, which is then sent to the steam pipeline network of the coking plant to replace some gas boilers.
Zero leakage vacuum heat recovery device heat exchanger for desulfurization flue gas in coking plant
3. Temperature stabilizer for vacuum thermal energy recovery device with zero leakage of activated carbon desulfurization flue gas in steel plants
Activated carbon desulfurization flue gas zero leakage vacuum heat recovery device cooler (stabilizer) for steel plants
4. Engineering application of zero leakage vacuum heat recovery waste heat boiler in sintering machine large flue
Diagram of the original finned tube direct heat exchange and recovery system
5. Zero leakage vacuum thermal energy recovery device for desulfurization wastewater, salt concentration multi effect evaporator
Separation type zero leakage vacuum heat recovery device heat exchanger (multi effect evaporator) for multi effect evaporation and concentration
