184- Vane separator for the technical upgrade of the light plate, Xuefulong baffle and demister at the inlet of magnetic levitation vacuum pumps

This post was last edited by luoli519 on 2021-6-22 at 18:39. In industries such as petrochemicals, vacuum pumps are common operating equipment used for vacuum distillation, negative pressure feeding, and exhaust ventilation. Recently, environmental emission regulations have become very strict. Many companies have installed VOCS treatment systems to capture, through negative pressure ventilation, the volatile organic gases and dust generated during factory operations; water washing and adsorption processes are then used for further treatment. Vacuum pumps play a crucial role as the key equipment in these systems. Due to the high-speed rotating components inside the vacuum pump, this not only places higher demands on vacuum pump technology but also imposes greater requirements on the purification of the airflow entering the vacuum pump.

To ensure the wear-resistant and long-term operation of the rotating components in a vacuum pump, the magnetic levitation vacuum pump is one of the options. However, magnetic levitation vacuum pumps are delicate and require higher standards for the purification of the inlet airflow. Especially in VOCS treatment units and gas extraction systems, the airflow carries not only liquid droplets and foam, but also sand particles, dust, and even fibers. Traditional vacuum pumps do not have any air purification device at their inlet, and magnetic levitation vacuum pumps, which are now used, also do not receive much attention in terms of inlet air purification; as a result, these sensitive magnetic levitation vacuum pumps often break down, leading to high repair costs. The company blames the vacuum pump manufacturer for poor quality, while the vacuum pump manufacturer claims that the air supply provided by the client is of poor quality.

A Sino-foreign joint venture company in Tianjin that manufactures magnetic levitation vacuum pumps encountered the same problem. It’s no wonder; after all, the owners are not familiar with the equipment related to air intake separation technology for magnetic levitation vacuum pumps. In fact, even professional manufacturers of magnetic levitation vacuum pumps are not well-versed in such technology either. Separation technology and vacuum pump equipment are far apart from each other. But the owner said that the maglev vacuum pump is manufactured by your company, so it is your responsibility to provide the inlet airflow separation equipment, with the cost to be borne by the owner. So, this manufacturer of maglev vacuum pumps found a company in Tianjin that claimed to be able to use the Xuefulong baffle demisters made from its own plastic to solve this problem. Thus, with the help of the vacuum pump manufacturer, the owner installed a Xuefulong baffle demister made of plastic, sourced from a local company in Tianjin. However, the actual operating effect was limited, as a considerable amount of liquid was still collected at the inlet of the vacuum pump.

This post was last edited by luoli519 on 2021-6-22 at 19:33. The image below shows the components of the demister that were taken out by the customer:

This is also the demister internals used at the inlet of this magnetic levitation vacuum pump.

Looking closely at these baffle plates, they are entirely made of plastic; some of them have evenly shaped holes while others have irregular shapes. Moreover, the spacing between the baffle plates varies greatly – some areas have larger gaps and others smaller ones, indicating a shoddy quality. Take a look at the picture below:

This post was last edited by luoli519 on 2021-6-22 at 19:45. When viewed from the side of the baffle demister, it resembles the single-stage plastic flat-panel Sevron baffles that were used abroad in the earliest years of the last century. No wonder the separation efficiency is low. Is such a product still chosen by joint ventures? It’s a bit funny.

Let’s carefully analyze the actual operating conditions: Wet, saturated air containing liquid droplets and a small amount of fibers, at an operating temperature of 40°C and an absolute pressure of 30 kPaA, flows at a rate of 600 m³/min through a 600-mm-diameter pipeline into a separator. The purpose is to remove the liquid droplets and fibers from the air before it enters the magnetic bearing turbo vacuum pump. However, based on the pictures of the original separator internals provided by the customer, it can be seen that the internals used are domestic replicas of the first-generation, simple and low-cost Chevron baffle plates used for demisting, which were first employed abroad in the 1940s. This earliest type of low-cost, simple demisting internal component lacked specialized flow channel structures for capturing and collecting the substances carried by the airflow. The separation units arranged in series within these components were few in number – usually just 1 unit, or at most 2 units – which resulted in a low efficiency in separating the substances present in the airflow. It also had limited operational flexibility and was unable to cope with the unstable conditions that occur when the airflow is under vacuum. Furthermore, based on the images of the separate components provided by the customer, it appears that these components are made of conventional plastics such as PP or PVC. Their performance in terms of resistance to airflow impact loads, medium-to-high frequency vibrations, temperature resistance, and aging in humid air environments is far inferior to that of stainless steel; as a result, they tend to deform, age, and become brittle within a lifespan of 3–4 years or even less, necessitating the complete replacement of the original components.

To prevent the original separator from continuing to operate inefficiently, which would result in an excessive amount of liquid foam in the outlet and thus cause significant interference with and damage to the core components of the high-speed rotating magnetic levitation turbine vacuum pump, and also with the aim of extending the service life of the separation elements and reducing their operational and maintenance costs, NOVEL recommends, based on its expertise in dynamic gas-liquid separation technologies, that the owner use vane separators instead of the existing simple, low-cost Chevron baffle plates used since the 1940s. This approach will improve the gas-liquid separation performance under varying operating conditions, meeting the requirements for high operational flexibility, efficient and stable separation, and resistance to aging. It also helps to effectively protect the core components of the high-speed rotating turbine vacuum pump while reducing operational and maintenance costs.

For the purification and separation of high-velocity, liquid-laden gas streams at the inlet of vacuum pumps, vane separators have been widely used in similar applications across industries such as petrochemicals, coal and coke chemistry, oil and gas extraction, processing, and transportation, fine chemicals, pharmaceuticals, paper manufacturing, metallurgy, salt production, environmental protection, and new energy sectors. As an upgraded version of traditional simple separation devices, the feather-leaf separator boasts the following performance features and advantages: 1. Thanks to its patented feather-leaf separation technology, it is highly efficient at separating droplets and mist with a wide range of particle sizes present in the gas stream; it can typically remove droplets and mist with sizes of 5–8 meters or larger with an efficiency of 99.9%. The first generation of simple, low-cost Chevron baffle plate demisting and filtration separators were unable to achieve efficient and quantitative separation of gas and liquid; moreover, they could not remove liquid droplets and bubbles larger than 5–8 microns with 99.9% efficiency. 2. The patented technology equipment for vane separation offers greater operational flexibility under gas-liquid separation conditions, with an operational flexibility range of 15% to 130%. Traditional simple separators have an operational flexibility upper limit of 110%; overload due to significant fluctuations in operating conditions often causes the airflow to contain a substantial amount of liquid, which in turn disrupts the stability of production operations in downstream equipment. 3. The patented technology for vane separation enables the separator to have a smaller size and occupy less space under the same operating conditions and separation efficiency requirements. Under the same operating conditions and separation efficiency requirements, the diameter-to-wall thickness ratio of the vane separator is 30-40% smaller than that of conventional separators. 4. The patented device for separating feather leaves is made of stainless steel; it can operate continuously and stably for up to 20 years, with extremely low operating and maintenance costs. 5. Patent technology equipment for separating feather leaves, equipped with an online self-cleaning system. If necessary, the feather-leaf separation internals assembly can be designed as a detachable structure, allowing it to be removed from the separator body for cleaning during overhauls, thus enabling simple and convenient maintenance. 6. Based on the operating characteristic curve of the patented equipment for separating feather leaves, this separator maintains a stable pressure drop and separation efficiency throughout its extremely long service life. Its operating curve is essentially a straight line; therefore, it is an ideal choice that meets the requirements of quality management systems ； In contrast, with other traditional separation devices, the operating pressure drop and separation efficiency are acceptable at the beginning of operation of the new equipment; however, as operation time increases, clogging worsens, the operating pressure drop soars, and the separation efficiency drops significantly, until it becomes necessary to replace the internal components again. Their performance curve is a zigzag pattern with many large fluctuations, making them traditional technical devices that quality management systems strive to avoid as much as possible.