Tags: #Heat Tracing; #Continuous Vacuum Cooling Crystallization; #Insulated Vacuum Cooling Crystallization; #Flash Distillation; #Heat Transfer Compounds
A Continuous Vacuum Cooling Crystallization system makes saturated solution to be cooled and crystallized through insulated vacuum equipments. Hot solution flows into a crystallizer. When it arrives separation chamber, the solution flash evaporate. The solution begins to crystallize during the cooling process caused by the evaporation.
This technology, crystallization through solution’s cooling, is suitable for materials which solution’s solubility apparently positive correlation with temperature.
Traditionally, the industry uses batch-type crystallization process model in a reactor. Continuous Vacuum Cooling Crystallization process breaks through several technical barriers and allows you to adjust granularity, etc. It provides more even and purer particle in a more automatic way. Now the crystallization process is used in chemical, pharmaceuticals and agriculture industry. It is commonly utilized in the production of oxalic acid, butanedioic acid, sodium citrate, and Magnesium sulfate heptahydrate. These product have special requirements for crystallization temperature, granularity and crystal distribution.
According to “Crystallization” section in “Chemical Process Guide”, crystal production is depends on solution’s characteristics, crystallizer inner surface status, and the adjustment or control of the entire parameters of the process. Most solution’s characteristics will change along with the temperature becomes high or low. Amount all the parameters, temperature is related to all aspect of the process. So, temperature is the key for high quality crystal production.
The problem in a large-scale Continuous Vacuum Cooling Crystallization system is that the reactor is too huge to keep internal temperature even. This will generate crystal dirty which is the inhibitor to continuous production. Applying HTT heat transfer compound in the heat tracing system, we can provide more even heat tracing and reduce the temperature difference between the external wall and the center of a reactor. The fewer crystal dirty generated, the more maintenance time reduced.
HTT heat transfer compounds greatly improve thermal exchange efficiency between tracing pipe and crystallizer by establishing even and rapid heat transfer. HTT has significant practical meaning for crystal production process.
Tags: Heat Tracing; Spandex textile; Spinning Chimney; Heat Transfer Compounds
The spandex production process involves various physical changes and chemical reactions. Not just including the heat transfer process, but also has a material transformation process. Dry-spinning technology is commonly used by domestic companies today, with spinning speed of around 400-900M/min. To reduce production cost, boost productivity, increase spinning speed and improve the quality of spandex products, are the key challenges we are facing today.
Today, the size of the spinning chimney used by domestic companies is small. Its side air flow rectifier and sparger are bulky with poorly designed structure. These systems apply steam tracing or electrical tracing solutions. The amount of temperature raised by hot air flow is limited. The insufficient and unevenly heat tracing can only support the spinning speed less than 500M/min. All these have a very negative impact on the quality of spinning. Moreover, if we recklessly increase the spinning speed, the density of DMAc in chimney will be raised to an explosion threshold.
It is in the spinning chimney that the spandex fiber formed and solvent volatilized and recovered. The stability and evenness of temperature have a significant impact on the DMAs’ volatilization and have a decisive effect on many quality indexes of spandex fiber.
Published by the government regulation in 2015, GB/T 51109-2015, “The Standard of Spandex engineering equipment Installation and quality acceptance inspection” already stated that any rectangle spinning chimney should use heat tracing system with heat transfer compounds between tracing pipe and spinning chimney. You have to make sure the heat transfer compounds are completely dry before the installation of insulation.
HTT heat transfer compounds replace radiant and convective heat transfer with direct contact heat transfer to make heat transfer more evenly and effectively. By doing so, we can stabilize the temperature of the spinning chimney, improve spandex product quality, reduce energy consumption and ensure sustainable production of high-quality spandex.
Tags: #Heat Tracing; #SCR process; #Selective Catalytic Reduction; #deNOx; #Hydrolyzation Process; #Heat Transfer Compounds
Today, most of the coal boilers in China widely employ SCR (Selective Catalytic Reduction) process to reduce NOx emissions. Based on the storage and production of reduction agent, the SCR process can be categorized as liquid ammonia process, urea pyrolysis process and urea hydrolyzation process. Urea hydrolyzation utilizes steam as heating source, which is more popular for economy and safety concerns. Today, most of power plants employ hydrolyzation process for ammonia gas production in China.
In hydrolyzation process, the ammonia gas mixture need to be kept above 140℃ (284℉) when it is transited to the flue for deNox. However, the problem is that it is common to have the steam retrograded and ammonium carbamatecrystallized because of the inappropriate design and maintenance of the hydrolyzed urea gas flue. If this problem continued to happen, the crystallization would finally block the flue and cause safety issue.
To solve this problem, our technical support team had come up with a solution by simply adding our heat transfer compound into the existing heat tracing system. We greatly improve heat tracing performance by increasing the contact area and changing the heat transfer from convection to conduction. The temperature had been well controlled and the steam retrogradation and ammonium carbamate crystallization had almost been minimized to none. By doing so, our heat transfer solution had greatly helped our customer in solving the occlusion of the gas deNOx flue.