In modern industrial production, Decanter Centrifuge has become an important equipment in sewage treatment, chemical, food, medicine, environmental protection and other industries with its continuous, efficient and automated solid-liquid separation capabilities. However, the investment cost of adding a new decanter centrifuge is not low. Sometimes buying a second-hand decanter centrifuge can significantly reduce the initial investment of the enterprise while ensuring the functional requirements. We sell Used decanter centrifuges to meet your needs.
Why is the Used decanter centrifuge so popular?
1. Financial pressure and cost-effectiveness coexist
High investment cost: A new decanter centrifuge usually includes a package of expenses such as the main body, drive device, PLC control system, supporting pumps, pipeline valves, installation and commissioning, etc., which often cost hundreds of thousands or even millions of RMB. For small and medium-sized enterprises or start-up projects, the initial one-time investment pressure is relatively high.
Used equipment has a significant price difference: Compared with new machines of the same model, the market price of second-hand decanter centrifuges is generally lower than 50% or even 70%. Reasonable selection can achieve the functions required for “hardware upgrade” while reducing investment by 30% to 50%, significantly reducing financial pressure.
Fast landing: Many used equipment are idle after being disassembled by the original owner, and can be delivered quickly after renovation and testing – compared with the new equipment, which often takes several months from factory customization to factory commissioning, used equipment can meet production needs faster.
2. Industry Upgrading and Elimination
Technology Iteration: With the advent of new high-efficiency and low-energy horizontal screw centrifuges, some companies have replaced old models in pursuit of higher production capacity and more intelligent control. This has led to a large number of idle equipment with “acceptable performance” on the Used market.
Capacity upgrade or process adjustment: For example, when sewage treatment plants upgrade sand-water separation and sludge concentration processes, they will replace the original small and medium-sized centrifuges and put them on the Used market; when chemical or food companies change production lines, they will also release centrifuges that are still within their service life.
3. Market chaos requires caution
Information opacity: Many Used equipment information is based on simple text descriptions, often lacking detailed technical parameters, service life, fault history, maintenance records and other key data.
Quality is uneven: Some second-hand equipment has not been professionally tested, and problems such as mechanical wear, seal aging, and differential failure are not easy to see. Blindly acting can easily lead to Used investment or downtime losses.
Risk of transaction disputes: If the buyer and seller fail to sign a comprehensive warranty and acceptance agreement, it will be difficult to hold them accountable if problems arise later, which may result in the cost of repairs far exceeding the price difference of the equipment, which would be counterproductive.
Clarify the needs and budget
Clarify the production conditions and processing volume
Before investing in the purchase of second-hand horizontal screw centrifuges, enterprises need to conduct a full investigation and analysis of their own working conditions:
Material properties
Sewage, sludge viscosity, solid content range? (For example, the solid content of sludge is generally between 1% and 5%)
Chemical slurry viscosity, corrosiveness, temperature requirements? (Some chemical organic solvent conditions require corrosion resistance and stainless steel materials)
The food industry must meet the sanitary requirements, and the material must be food-grade stainless steel.
Whether the sand content, oil content, and viscosity of oil drilling mud are high, it is necessary to consider details such as collar/overflow separation.
Processing capacity requirements
Daily processing volume or hourly processing capacity (tons/hour, m³/h).
The continuous operation time of the equipment (24 hours/8 hours/intermittent).
Whether multiple units need to be operated in series or parallel, and grid-connected.
Environmental and process requirements
The size of the site space and the direction of the inlet and outlet pipelines.
Ground load bearing (whether the base needs shock absorption or anti-vibration pads).
Slag discharge method (water washing, pneumatic slag removal, spiral forced discharge, etc.).
Degree of intelligence: whether PLC control, frequency conversion speed regulation, remote monitoring, etc. are required.
We purchased the Used decanter centrifuge before inspection
1. Appearance inspection: Preliminary judgment of “health status”
Appearance paint and rust
Freshly peeled paint, rust, weld fractures, obvious depressions, etc. may indicate severe impact or corrosion.
If a large number of rust or corrosion points are visible, it is necessary to focus on the material and whether it meets the food grade/medical grade requirements.
Drum and spiral outer surface
Observe whether there are obvious scratches or peeling on the inner and outer walls of the drum; whether the spiral blades are worn or deformed.
Tap the surface of the drum gently, and the sound emitted by each part should be uniform and there should be no obvious hollow sound; if the hollow sound is obvious, the internal coating of the drum may be peeling or locally corroded.
Interface flanges, pipes and valves
Check whether the inlet and outlet flanges are intact, whether the flange bolt holes are intact, and whether the bolts are rusted and brittle.
Whether the discharge port flange and the slag discharge port bushing are severely worn; whether the valve handle is flexible and there is no obvious leakage.
Base and vibration damping device
Check whether the base is deformed or cracked, and whether the vibration damping spring or rubber vibration damping pad is aged and ineffective.
Check the tightness of the base bolts. If the bolts are missing or loose, it may be improperly operated during transportation or disassembly.
2. Core component inspection: focus on operating life and performance degradation
Differential and transmission
The differential determines the relative speed between the spiral and the drum, and is an important component that affects the separation effect.
Remove the differential housing and visually inspect the gear meshing surface: the gear meshing surface should not have obvious peeling and wear granulation; the gear tooth side tooth surface should be smooth.
Test the differential mechanism, and there should be no abnormal sound (such as creaking or collision) when the spiral is manually driven to rotate.
If the hot oil inside the differential is turbid and there are metal chips, the life of the differential is nearing the end.
Main bearings and sliding bearings
Horizontal screw centrifuges usually use four-point or two-point bearing support. Check whether there is oil leakage, smoke, and rolling friction sound at the bearing seat.
The wear condition of the main bearing (sliding bearing) is particularly critical: if the gap between the bearing sleeve and the journal is too large, violent vibration will often occur during startup, affecting the service life.
Vickers hardness test: You can ask a professional team to test the hardness of the bearing material. If the hardness value is low, there may be problems of overuse or quality defects.
Spiral shaft and blades
Check whether the surface of the spiral blade is uniform and whether the blade gap is consistent; whether there are blade fractures, warping edges, and local depressions.
Use a micrometer to measure the concentricity and gap between the spiral and the drum. Generally, the gap is required to be around 0.3-0.5mm; too large or uneven may lead to a decrease in separation efficiency.
For spirals with cooling jackets, open the jacket to observe whether there is blockage, scale or corrosion inside.
Drum body and liner
The inner side of the drum body usually has a wear-resistant liner. When the liner is severely worn, it needs to be replaced, otherwise the separation effect will be reduced, and even material leakage will occur.
Remove the liner to measure the thickness: If the remaining thickness of the liner is less than 50% of the design thickness, its remaining life is limited; it is recommended to be cautious or consider replacement.
Whether there are local depressions or cracks in the drum body, especially whether there are signs of crack expansion at the weld.
Lubrication system and oil sealing mechanism
Check the cleanliness of the oil in the lubricating oil tank, whether there is emulsification, precipitation, particles, etc.
Check whether the oil sealing ring and sealing expansion sleeve are aging, cracking, or not sealed tightly; if grease leakage is found, it can be judged that the sealing effect has decreased.
If conditions permit, after replacing the lubricating oil, analyze the iron content in the oil to determine the degree of wear of the bearing and differential.
Motor and control system
The motor nameplate parameters (power, speed, insulation level) must be consistent with the original configuration; if it is found that the motor power is too small or the insulation level is low, it may be a low-end accessory replaced later.
Whether the motor winding is burned out and whether the insulation resistance meets the standard (generally, a megohmmeter is required for insulation testing, and the insulation resistance > 1MΩ is qualified).
Whether the electrical components such as the PLC control cabinet and the inverter are equipped by the original factory, whether the line routing is standardized, and there is no looseness or cold welding.
The machine can be turned on and run idly to observe whether the motor running sound is stable and whether there is any abnormal sound; at the same time, check whether the motor temperature rise is abnormal.
We hope to help you fully understand the Used equipment and rationally evaluate the costs and benefits, so that you can purchase a reliable, economical and practical decanter centrifuge with the best cost-effectiveness to protect your company’s production. If you have any questions or need further technical support, please feel free to contact us. We will wholeheartedly provide you with a full range of services.
