The selection and design of expansion joint of pulverized coal pipeline needs to consider many factors comprehensively to ensure that it can effectively cope with the special working conditions of pulverized coal conveying system, and ensure the safety and reliability of the system. Here are the key considerations:
1. Working conditions
Temperature range: Determine the operating temperature range of the expansion joint, including maximum and minimum temperatures. Pulverized coal pipelines usually work at higher temperatures, so the expansion joints need to be made of high temperature resistant materials.
Pressure rating: Determine the working pressure of the system and select the type of expansion joint that can withstand this pressure.
Properties of media: Considering the abrasion and potential explosion risk of pulverized coal, the expansion joint should have good wear resistance and sealing performance to prevent the leakage of pulverized coal or the entry of outside air to cause explosion.
2. Compensation requirements
Type and quantity of displacement: Assess possible axial, lateral and angular displacements of the pipe and select expansion joints with corresponding compensation capabilities. For the case of large displacement, preference is given to the expansion joint of the sleeve type or the bellows combination type.
Installation space: Choose the appropriate size expansion joint according to the size of space available on site. Direct burial expansion joints are suitable for underground installation, while above ground installation has more options.
3. Material selection
Corrosion Resistance: The pulverized coal may contain trace moisture or other corrosive components, and the expansion joint should have good corrosion resistance to prevent corrosion damage after long-term operation. Commonly used corrosion resistant materials include stainless steel, nickel-based alloys, etc.
Abrasion resistance: Due to the strong abrasiveness of pulverized coal, wear-resistant materials, such as ceramic coating and cemented carbide, should be selected inside the expansion joint to prolong the service life.
- 4. Sealing performance
High efficiency sealing system: Choose designs with good sealing performance, such as packing seals, mechanical seals or bellows itself seals, etc., to ensure a tight seal even in the case of multi-directional displacement.
Regular maintenance: Although some expansion joints are advertised as "maintenance-free", it is still necessary to consider the design of easy inspection and replacement parts in practical applications to reduce long-term operation and maintenance costs.
5. Structural design
Fixing and guiding device: To prevent lateral displacement or torsion of the compensator during operation, fixed brackets and guide brackets should be installed in appropriate positions to guide the pipeline to move in the axial direction.
Pre-stretched or compressed (if necessary): For some expansion joints that require "cold tightening", appropriate pre-tension or compression is performed according to the design requirements during installation to achieve the best compensation effect at operating temperature.
6. Economy
One-time investment costs: Comprehensively compare the prices of different types of expansion joints and choose products with high cost performance.
Long-term operating expenses: Considering factors such as maintenance cost and replacement frequency, choose a design that is easy to overhaul and replace parts to reduce long-term operation and maintenance costs.
directly buried expansion joint: If applied to underground pipelines, special consideration should also be given to corrosion resistance and compression resistance to cope with soil environment and external loads.
High temperature and high pressure environment: For pulverized coal pipelines working under extreme conditions, the expansion joints should be made of high temperature and corrosion resistant materials and equipped with a reliable sealing system.
7. Ease of installation and maintenance
Easy to install: Choose products that are easy to install, reduce installation time and complexity, and avoid stress concentration problems caused by improper installation.
Preventive maintenance: Make a detailed maintenance plan to replace aged or damaged parts in a timely manner to ensure that the expansion joint is always in good condition.