191- The feather-shaped separator is used in a liquid-liquid separation and purification scheme for the inlet of high-vacuum molecular pumps in systems for the mild thermal evaporation and concentration of heat-sensitive substances

In industries such as petroleum refining, fine chemical manufacturing, pharmaceutical engineering, food engineering, and environmental protection, vacuum distillation is a commonly used process for the concentration and separation of high-boiling-point substances. Especially in the fine chemicals, pharmaceutical, and food industries, the materials subjected to distillation, evaporation, concentration, and separation are often high-value heat-sensitive products, which require distillation, evaporation, and concentration to be carried out under high vacuum conditions with minimal heating. At this point, the process stability of the vacuum system is crucial for the success or failure of the distillation, evaporation, and concentration processes involved in the production of heat-sensitive materials. The process stability of the vacuum system is poor, and as the vacuum level gradually decreases, it inevitably leads to an increase in the heating temperature of the heat-sensitive materials upstream. The thermal transformation of these heat-sensitive materials often results in side reactions and the formation of impurities, ultimately leading to defective products.

This post was last edited by luoli519 on 2021-8-26 at 16:22. The main factors affecting the stability of the vacuum system in vacuum distillation and evaporation equipment are, aside from primary faults in the vacuum apparatus itself, often process settings and process control issues that lead to unstable operation of the vacuum system. Such situations are more common, and it is even harder to identify the causes as well as find solutions. Because process settings and process safeguards are “established from the outset” during the initial phase of project construction and operation, they are not easily noticeable. Furthermore, the process setup and assurance for vacuum systems often require in-depth knowledge of fluid dynamics, which is not necessarily accessible or understandable to those with only a superficial understanding; as a result, it becomes even more difficult to identify the causes. Even if it is possible to identify the cause at the source, in terms of process settings and process assurance technologies, it involves more advanced fluid dynamics techniques, making it difficult to find a suitable and effective solution. This technical article precisely provides, through the relevant example solutions we have handled ourselves, a valuable approach and set of ideas for identifying and resolving similar problems.

This post was last edited by luoli519 on 2021-8-26 at 16:39. Here, an example of a technical improvement related to the secondary steam gas-liquid separation and purification process at the inlet of a high-vacuum molecular pump used in a certain pharmaceutical company’s project for the thermal concentration and evaporation of heat-sensitive drugs is presented to discuss and analyze ways to address the operational challenges in high-vacuum systems; similar methods can then be applied to solve problems in medium- and low-vacuum systems as well. The pharmaceutical company’s project for the micro-heat concentration and evaporation of heat-sensitive drugs involves using high-vacuum molecular pumps to create a high-vacuum environment, thereby enabling the heat-sensitive drugs to be concentrated at low temperatures using a short-path distillation evaporator to produce the desired product. However, at the initial stage of process design for this thermosensitive drug micro-heat concentration and evaporation project, the main efforts and investments were focused on short-path evaporation equipment and molecular pumps; it was assumed that since the product is produced in batch mode, the pilot and scale-up tests would be successful, and the industrial-scale installation could simply be built based on that. Looking back now, the scale of operation during the pilot and pilot-scale tests was likely insufficient; moreover, there may have been incomplete or inadequate aspects in the technical evaluation of those tests, which led to process technology defects remaining undiscovered until this stage.

This post was last edited by luoli519 on 2021-8-26 at 17:46. The short-path evaporator and high-vacuum molecular pump utilized in the pharmaceutical company’s project involving the microheating concentration and evaporation of heat-sensitive drugs are products of renowned manufacturers; they are quite valuable, and there is no doubt regarding their superior quality. The problem lies in the fact that the short-path evaporator generates secondary steam as a result of the mild thermal concentration and evaporation of heat-sensitive drugs; this steam contains a large number of highly viscous liquid droplets and mist. No efficient gas-liquid separator is installed to purify the stream by removing these droplets and mist before it reaches the inlet of the molecular pump. These droplets and mist enter the molecular pump, causing the working fluid in the pump to become diluted rapidly. This leads to a quick decrease in the vacuum level. Consequently, the concentration temperature in the short-path evaporator rises rapidly; as a result, heat-sensitive drugs produce numerous by-products and impurities due to overheating, rendering the products unfit for use.

According to the operational process description provided by the client for the pharmaceutical manufacturing equipment’s high-vacuum molecular pump, this pump is used to carry out mild thermal concentration of heat-sensitive drugs. During the concentration process, the highly viscous liquid droplets and mist, along with their vapor, are introduced into the high-vacuum molecular pump at a flow rate of 800 AL/s, through a 150 mm long pipeline, under conditions of an operating temperature of 50°C and an operating gauge pressure of -0.01 kPaG.

In response to the issue where the high-viscosity droplets and mist carried by the secondary steam during the micro-thermal concentration of heat-sensitive drugs affect the vacuum level and the quality of the product in such high-vacuum molecular pumps, NOVEL Company used its precise kinetic separation technology calculation platform to determine that, under these conditions, the average size of the droplets and mist carried by the secondary steam in the vacuum pipelines is 51.52 microns. The large amount of such droplets and mist remaining in the gas flow, if not separated before entering the molecular pump, will inevitably cause the working fluid inside the molecular pump to become diluted rapidly and the vacuum level to drop quickly. This, in turn, leads to an increase in the concentration temperature, resulting in the formation of numerous by-products and impurities due to overheating of the heat-sensitive drugs, as well as issues with product quality.

In order to effectively capture the droplets and mist carried in the inlet airflow of the vacuum pump and thereby reduce their impact on the proper operation of the molecular pump, NOVEL recommends, from the perspective of specialized dynamic gas-liquid separation technology, that two sets of vane separators be installed in parallel in the inlet pipeline of the vacuum molecular pump, one in use and one as a backup. This approach enables the effective capture of the large amount of droplets and mist present in the inlet airflow, thereby significantly extending the operational life of the molecular pump’s working fluid. It also helps to maintain stable vacuum levels and consistent drug concentration temperatures, preventing high-value thermosensitive drugs from producing excessive by-products and impurities, which could lead to defective products.

In fact, for the purification and separation of mixed gas streams containing tiny liquid droplets and mist, 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, papermaking, 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 3–10 microns or larger with an efficiency of 99.9%. Other separators find it difficult to achieve efficient and quantitative gas-liquid separation. 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 upper operational flexibility threshold of 110%; significant fluctuations in operating conditions often cause the gas stream to contain a substantial amount of liquid, which in turn damages the stability of production operations in downstream pipeline 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 technology equipment for vane separation is equipped with a vane separation internal component set that can be designed as a detachable structure along with quick-opening blind plates, allowing for the selective shutdown and removal of this internal component set from outside the separator for easy maintenance. 5. The patented technology for separating feather leaves features a longer operational cycle and high separation efficiency, making it an ideal choice to meet the requirements of quality management systems.

The pharmaceutical company owner has provided us with the following parameters regarding the inlet gas flow conditions of the high-vacuum molecular pump in this thermal-sensitive substance micro-evaporation concentration system: • Gas inlet and outlet dimensions, DN150mm (specified by the customer)； • Gas flow rate, 800 AL/s ； • Operating condition airflow pressure, -0.01kPaG ； • Operating condition air flow temperature, 50℃ ； • Air currents carry along particles, as well as highly viscous droplets and foam.

Based on the actual operating condition data provided by the customer, and using NOVEL’s precise dynamics separation technology as well as the system platform for calculation and configuration design, the main structural information of the vane separator equipment is as follows: 1. Separator type: Vane separator； 2. Separator model: NOVEL G50I-EDP 20-72.516-V; 3. Core separation internals assembly of the separator: 3.1 Internals assembly of the pre-distribution coalescer subsystem, model G50D, with a detachable structure ； 3.2 Vanes separating unit system internal components set, model G50I-EDP. 4. Separator material: SS304.