Clean steam generators can produce relatively clean steam to meet production process requirements, but they also have certain disadvantages and practical limitations.
Improper Selection
Improper selection can cause secondary contamination and increase energy consumption. If the selected clean steam generator does not match the actual application, secondary contamination may occur, defeating the original purpose of using clean steam. For example, in applications where industrial steam quality is a concern, direct steam heating is used, load fluctuations are large, pressure is insufficient, or steam flow demand is high, a clean steam ultrafiltration unit may be required. Choosing an incompatible type of clean steam generator in such cases can lead to steam contamination. In addition, when a unit designed for higher operating pressure is used at low pressure, equipment efficiency may drop and energy consumption may increase. Hansheng Automation can provide drawing-based custom machining for adapters, control valve components, and piping connections when standard configurations do not match actual steam conditions, helping improve system compatibility.
Limitations of Instantaneous Clean Steam Generators
Instantaneous clean steam generators are derived from pure steam generators used in the pharmaceutical industry. They are compact, occupy less floor space, and hold no stored water, so clean steam quality is relatively high. However, their simplified and weakened vapor-liquid separation structure often causes serious water carryover during load fluctuations. As a result, they are usually used in small-capacity applications with stable loads, generally not exceeding 1000 kg/h at 6 barg per unit. Lower evaporation pressure and clean steam usage pressure further reduce the maximum load capacity of a single unit, which is easily overlooked by equipment manufacturers. When load fluctuation causes excessive water carryover, improved separation internals or custom-fabricated baffles may be required. Hansheng Automation can machine these non-standard components according to customer drawings, helping users optimize equipment performance within design limits.
Limitations of Volumetric Clean Steam Generators
Volumetric clean steam generators are designed with reference to industrial reboilers. Their stored water heat capacity and larger vapor-liquid separation space reduce water carryover during load fluctuations. However, because they use RO water or demineralized water and cannot be protected by chemical agents, chloride ions accumulate as steam evaporates. When the chloride ion concentration exceeds 200 ppm, crevice corrosion becomes unavoidable if high-efficiency heat exchange tubes or plates are used. Even duplex stainless steel can only extend the corrosion time to a limited extent. For this reason, strictly defined clean steam generators generally do not use physically enhanced high-efficiency heat exchange tubes. Due to tube bundle volume constraints, the maximum design steam load of a single volumetric clean steam generator should be kept below 2000 kg/h. Chloride-induced crevice corrosion often occurs at tube-to-tubesheet joints and plate gaps, so material selection and precise machining of heat exchange components are critical. Hansheng Automation can supply duplex stainless steel or other corrosion-resistant tube bundles, tube sheets, and sealing parts based on customer specifications, supporting longer service intervals.
In addition, the shell volume of a volumetric clean steam generator must ensure a sufficiently large evaporation surface area to reduce the rate at which steam leaves the water surface, thereby controlling steam-water separation and preventing dissolved solids from being carried into the clean steam. A convenient evaluation method is to use heating intensity per unit volume, calculated as the ratio of clean steam output to the stored water volume. When this ratio exceeds 1000 kW/m³, clean steam dryness may decline and contamination risk increases.
Overall Operating Performance
Practical operating experience shows that correct selection is critical to the performance of clean steam generators. An improperly matched clean steam generator often delivers lower steam quality than a clean steam ultrafiltration unit. In some cases, a failed clean steam generator selection can be as damaging as contaminated industrial steam, affecting the entire production process and final product quality. During retrofit or replacement, non-standard flanges, tube sheets, and separation internals are often needed to match existing systems. Hansheng Automation offers precision machining based on customer drawings, helping users address compatibility and material durability issues without changing the original equipment structure.
