NEWSLETTER
ISSUE
Sep to Dec, 2016 Volume 1
DIN STANDARD 1.4435
Pharmalab is a leading manufacturer of Multi-Effect Distillation Stills for Water for Injection (WFI- Grade). Capacities range from 80 L/hour to 15,000 L/hour. With more than 1,000 installations worldwide, we enjoy substantial customer loyalty and patronage.
The latest features include a higher grade of SS 316L (DIN 1.4435), expanded pipes in the tube sheet plates, a non-condensable gas removal system for the feed water, a unique purification system due to the purging of endotoxin rich condensate from each column, reduced cooling water requirement, and energy saving capabilities due to the reduced boiler steam consumption.
HIGHER GRADE SS 316L (DIN 1.4435)
Pharmalab uses high quality stainless steel, i.e., SS 316L (DIN 1.4435) in manufacturing the Multi-Effect Distillation Still and pure steam generators. This grade of stainless steel provides improved resistance to pitting and crevice corrosion.
Over a period of consistent usage, the stainless steel equipment employed for pure steam or WFI generation tends to face the problem of intergranular corrosion. This is a form of corrosion where the boundaries of crystallite materials are more susceptible to corrosion than their insides due to the precipitation of chromium carbide, resulting into the formation of chromium depleted zones adjacent to the grain boundaries. This process is known as sensitization, and is a result of the exposure of steel to high temperatures.
SS 316L (DIN 1.4435) is attained through the optimization of composition and microstructure, as well as by the absence of hard inclusions. The composition has a higher density of chromium, nickel, and molybdenum, which significantly improve the resistance compared to other CrNi-steels, allowing the use of this steel at temperatures up to 450ĖC in continuous operation. The SS 316L (DIN 1.4435) can be well-polished, has high malleability, and excellent welding properties. Furthermore, this steel is also less susceptible to pitting. It contains a controlled sulphur concentration of 0.015 ā 0.03% that improves machinability. With all the above characteristics and increased impact strength, this stainless steel is increasingly suitable for the purpose, making it the first choice for premium manufacturers across the globe for pure steam and WFI generation systems.
Being an internationally renowned brand, Pharmalab too uses the best grade of stainless steel available in the market, i.e. SS 316L (DIN 1.4435), out of the numerous other options present (refer to Table 1). This ensures higher corrosion resistance, thus leading to truly durable equipment.
*source: www. outokumpu.com
NCGR
Pharmalab provides NCGR (Non Condensable Gas Removal) systems to improve the quality of steam, thereby increasing the efficiency of the steam generator and extending life of the equipment present in the path of the steam flow.
Non-Condensable Gasses (NCG) have a serious impact on both, the steam/WFI generation system and its application area, therefore the EN 285 guidelines have defined the quality of steam wherein the allowable limit of non-condensable gases is less than 3.5%, which is to be ensured and validated at regular intervals. In steam/WFI generation systems, the NCGs reduce the heat transfer efficiency by 21%* or more depending on their concentration within the system. Usually, the non-condensable gases, if not removed, form a stagnant film on heat transfer surfaces, thereby adding resistance to the heat transfer and affecting the efficiency of the column. NCGR is used to prevent this issue.
Moreover, NCGs also affect the sterilization process, energy efficiency, and the life of the equipment. This is because the NCG present within the steam can insulate the products, inhibiting the heat penetration to its surface, thereby resulting in improper sterilization.NCG removal helps in controlling TOC (Total Organic Carbon). The United States Pharmacopeia and European Pharmacopeia recognizes TOC as a required test for purified water and WFI with its limit set to 0.5 mg/ml.
Pharmalab’s new and advanced column design ensures that the water flows continuously at an elevated temperature, helping with the liberation of NCGas directed via CGMP while avoiding any stagnation in the system.
The internal design of the column enables the water to flow through a larger surface area in order to elevate temperature and effectively remove the NCG present through the vent filter.
*Source: www.plantengineering.com.
THIS HURDLE IS ADEQUATELY ADDRESSED BY DEVELOPING EXPANSION JOINT DESIGN
The welding joints where the tubes are connected to the tube sheets in the WFI and pure steam generation plant are more prone to corrosion and leakages than any other components within the system. Analysis indicates that the welding joints lead to a microstructure change of the tube in the metal region as the joint is created by fusing the tubes to the tube sheets. This change in microstructure, when subjected to extreme conditions of temperature, pressure, and a high flow of water comprising of several oxidized gasses results in corrosion followed by leakage. Secondly, the tubes and its joints are subjected to temperature variation due to the continuous heating and cooling in the operation cycle; this variation also induces stress at the joint, leading to the development of cracks, resulting in leakage, contamination, and ultimately to the production breakdown.
This hurdle is adequately addressed by expanding the joint design. Here, the tubes are connected to the tube sheet by expanding them in the tube-sheetās double grove through a unique expansion process. This is done by applying uniform torque, thereby maintaining equal strength, resulting in leak-proof joints, unlike the welded joints. This tube-to-tube sheet joint eliminates stresses that arise due to the welding process, and thus overcomes corrosion, cracks, leakage through the welded joints, and the contamination of the product, leading to an uninterrupted and trouble-free operation of the Multiple Effect Distillation Still.
UTILITY SAVINGS FEATUR
Our continuous drive for the development of energy efficient equipment has resulted in a newly evolved WFI plant which incorporates an increased number of columns. This enables the optimum use of the previously unutilized energy. The fundamental principle remains that in the Multi-Effect Distillation Still, the first column is heated by an external energy source (boiler steam), and the pressure/temperature gradient is maintained across individual columns, enabling it to perform without any additional energy consumption. By optimizing the steam pressure in the first column and increasing the number of columns and pre-heaters, we have absorbed the available energy efficiently, resulting in the reduced consumption of plant steam (boiler steam) and cooling water.
With an increased number of columns, the pure steam temperature gradually decreases while progressing through each column so the temperature of the steam in the last column is lower than in the systems which utilize the regular 5 or 6 column design. This lowers steam temperatures, reducing the ĪT at the cooler,resulting in the cooling water requirement reduced dramatically.
Similarly the heat energy is optimally extracted by passing feed water through each of the additional pre-heaters installed within every column. As a result the feed water in the machine with additional columns attains higher temperatures before entering the first column. This increased temperature reduces the ĪT required within the first column, resulting in lower plant steam consumption.
