What parameters must be clarified before selection?
Provide the manufacturer with normal and minimum acid concentration, continuous and maximum temperature, flow rate, head, inlet pressure, start and stop methods, and indicate whether it contains chloride ions, fluoride ions, solid particles or other impurities. It should also be confirmed whether the temperature and pressure at the shaft seal are allowed, whether a small amount of leakage of process fluid is allowed, and whether a sealing auxiliary system is available on site.
Among them, the minimum concentration and maximum temperature should be checked at the same time. For example, if water enters the system when starting and stopping, the acid concentration may temporarily deviate from the normal value, and the materials originally selected based on stable operating conditions need to be re-evaluated. Corrosion data from alloy suppliers often also use concentration, temperature and impurity conditions to determine suitability.
How to choose the overflow material for high temperature concentrated sulfuric acid pump?
Check the complete working conditions first, and then compare the alloys
The materials for the pump casing, impeller, bushing and wetted parts of fasteners all need to be checked one by one. 316L, 904L, 20Cb-3 and nickel-based alloys can be included as candidates, but they cannot be directly determined based on "sulfuric acid resistance" or material grade. Corrosion data at corresponding concentrations and temperatures should be obtained from material and pump manufacturers, and the performance in castings, welds, and actual industrial acids should be checked. According to Haynes, sulfuric acid concentration, temperature, and chloride ion contamination may all alter alloy corrosion rates.
Pay attention to weak parts outside the pump body
Even if the pump casing material is suitable, the shaft sleeve, impeller mouth ring or seal cavity components may still corrode first. When purchasing, the manufacturer should be required to list the grade of each wetted part in the material list, and explain what basis for verification is used, instead of just providing a "pump body material".
How does the mechanical seal match high-temperature concentrated sulfuric acid?
Seal selection should also check the corrosion resistance and temperature range of the sealing end face, elastic components, springs and metal parts. For corrosive media, the structure that isolates metal parts such as springs from the process fluid can be evaluated; PTFE bellows seals have product examples for corrosive media such as concentrated acid, but the specific model still needs to be approved based on temperature, pressure and rotation speed.
If leakage control requirements are strict, the double-end seal, isolation fluid and monitoring plan should also be discussed with the manufacturer, and the impact of contact between the auxiliary fluid and process acid should be confirmed. Don’t regard “double-end face” as automatically applicable: Whether the auxiliary system can operate stably is also related to the seal life.
What are the differences between different engineering scenarios?
The dry suction cycle and finished acid delivery of the sulfuric acid production unit may use different temperature and flow conditions; the heat recovery system requires further verification of the impact of high temperature conduction on the bearing and sealing areas. The conventional concentrated sulfuric acid pump listed on Feiyue's official website is suitable for relevant working conditions of **93%~98% sulfuric acid and the delivery temperature is not higher than 110℃**; the website also lists high-temperature solutions for HRS systems, **190~220℃**. The two sets of conditions correspond to different designs, and you should make it clear which one you belong to when making an inquiry.
FAQ: Can the original pump materials and seals be used directly?
Only when the acid concentration range, maximum temperature, impurities, pressure, and start-up and stop processes of the old and new working conditions have been verified, it is suitable to be considered for use. In particular, the modified heat recovery system cannot be judged solely based on the original pump's "conveying super concentrated sulfuric acid". When abnormal corrosion or frequent seal failure occurs, the media sampling results and the actual working conditions of the seal chamber should be checked at the same time, rather than just replacing more expensive materials.
What should the manufacturer be required to deliver when purchasing?
It is recommended to attach a complete working condition table to the inquiry document, and require a reply: the material grade and basis of each wetted part, sealing structure and auxiliary scheme, material or sealing application range, performance curve, and suggestions for handling abnormal working conditions. For industrial acids with high temperatures or large fluctuations in composition, the final solution can be confirmed by combining actual media tests and existing operating records. Material manufacturers also recommend that when in doubt, conduct testing with media close to actual working conditions.
Feiyue has set up a High temperature concentrated sulfuric acid pump product page. The purchaser can submit concentration, temperature, flow, head and impurity information, and the engineering team will further check the flow materials, sealing and cooling configurations; the materials and temperature range listed on the product page should be used as the starting point for program discussion, and are ultimately confirmed based on specific working conditions.
