Buying a filter press requires comprehensive consideration of specific application scenarios, material characteristics, and production requirements to ensure the suitability, efficiency, and economy of the equipment.
First, clarify the material characteristics: the core basis for filter press selection
The nature of the material directly determines the type of filter press, filter material selection, and operating parameters. It is necessary to analyze the following indicators:
1.Material state and composition
Type of solid-liquid mixture:
Suspension (such as mine tailings, chemical slurry): It is necessary to pay attention to the particle size (whether it contains fine viscous particles, which affects the formation rate of filter cakes) and concentration (low concentrations may require pretreatment, such as flocculation).
Colloidal materials (such as food wastewater, sludge): high viscosity, need to choose a strong sealing, high-pressure dewatering model (such as a diaphragm filter press).
Corrosive: If the material contains acid and alkali (such as electroplating wastewater, chemical reaction solution), anti-corrosion materials (such as stainless steel body, acid and alkali filter cloth) should be selected to avoid equipment corrosion.
Temperature: High-temperature materials (such as high-temperature crystalline liquid, steam condensate) need to confirm the upper limit of the temperature resistance of the filter press, and the filter material needs to be made of high-temperature resistant materials (such as polypropylene, aramid filter cloth).
2.Filter target requirements
Moisture content of filter cake: If filter cake transportation or resource utilization (such as coal slime recycling) is required, a diaphragm press type needs to be selected, and the moisture content can be reduced to less than 30%; the moisture content of ordinary chamber filter presses is usually 40% -60%.
Filtrate clarity: high clarification requirements (such as food and pharmaceutical industries) require the selection of high-precision filter cloth (such as monofilament filter cloth) or the addition of filter aids (such as diatomaceous earth), and if necessary, secondary filtration equipment.
Second, determine the type of equipment: match the model according to the scene
Filter presses can be divided into the following categories according to their structure and working principle, with significant differences in application scenarios:
Model, core features, applicable scenarios, advantages, limitations, box filter press, filter plate without diaphragm, pressing by feed pressure, low moisture content requirements, low cost of ordinary industrial wastewater (such as printing and dyeing, papermaking), simple structure, general dehydration efficiency, filter cake is loose, diaphragm filter press, filter plate contains elastic diaphragm (rubber/polypropylene), can be pressed twice, high dehydration demand (such as municipal sludge, mine tailings) Low moisture content, filter cake drying, high cost, slightly complicated maintenance, plate and frame filter press, filter plate + filter frame are alternately arranged, filter cloth can be disassembled separately, high concentration materials, small batch intermittent production (such as chemical crystallization) High filtration accuracy, durable filter cloth, low degree of automation The operation is cumbersome, the belt filter press runs continuously, and the filter belt is used for extrusion and dewatering. Large-scale continuous production (such as municipal sludge and coal washing wastewater) has large treatment capacity, high automation, high moisture content, and the filter belt is easy to wear. Selection suggestions:
Intermittent production, small batch materials: priority chamber or plate and frame filter presses.
High dehydration demand, strict environmental protection standards: must choose a diaphragm filter press (such as municipal sludge harmless treatment).
Large-scale continuous operation: belt filter presses are more efficient (requiring pretreatment equipment to reduce material viscosity).
Third, Evaluating production parameters: matching productivity and efficiency
1.Processing capacity requirements
Calculated by the amount of solid-liquid mixture handled per hour/day, combined with the material concentration (e.g. 10% concentration of sludge, 10 tons per hour, the actual dry mud volume is 1 ton).
Note: The "theoretical processing capacity" of the filter press needs to be deducted from the auxiliary time (such as loading, unloading, cleaning), and the actual effective processing time is usually 60% -80% of the running time of the equipment.
2.Filter area and filter plate specifications
Filtration area: core parameters, the calculation formula is: filtration area (m2) = treatment capacity (m ³/h) × filtration time (h) ÷ filtration rate (m ³/(m2 · h)). The filtration rate needs to be determined according to the material characteristics test (such as ordinary sludge filtration rate about 0.05-0 m ³/(m2 · h)).
Filter plate size: Common specifications include 500 x 500mm, 800 x 800mm, 1000 x 1000mm, etc. Large-sized filter plates have a large processing capacity in a single batch, but the equipment covers a large area. Small-sized filter plates are more flexible and suitable for small batch and multi-batch production.
3.Degree of automation
Manual type: artificial loading board, unloading cake, suitable for small batch, low-frequency production (such as laboratories, small workshops), low cost but high labor cost.
Semi-automatic type: automatic pull plate, manual cake unloading, taking into account efficiency and cost, suitable for small and medium-sized enterprises.
Fully automatic type: automatic feeding, pressing, pulling plate, unloading cake, cleaning filter cloth, reducing manual intervention, suitable for large-scale production or high hygiene requirements (such as food, medicine), high initial investment but long-term labor saving.
Fourth, Focus on core configuration and materials: affecting equipment life and stability
4.Filter plate material
Polypropylene (PP): Corrosion resistant, light weight, suitable for medium and low temperature, non-strong acid and alkali materials (such as municipal wastewater), cost-effective, is the mainstream choice.
Rubber diaphragm: For diaphragm filter presses, it is necessary to choose oil-resistant, acid-resistant nitrile rubber or ethylene propylene diene (EPDM) to avoid material corrosion and damage to the diaphragm.
Cast iron/stainless steel: high temperature and high pressure resistance, suitable for high temperature materials or strong wear scenarios (such as mine pulp), but heavy weight and high cost.
5.Filter cloth selection
The filter cloth is the filter core and needs to be selected according to the particle size and chemical properties of the material:
Woven filter cloth (monofilament/multifilament): good wear resistance, suitable for large particle materials (such as coal washing).
Non-woven filter cloth: high filtration accuracy, suitable for fine particulate materials (such as chemical slurries).
< unk > Material matching: polyester acid resistance but not alkali resistance, nylon alkali resistance but not acid resistance, polypropylene acid and alkali resistance but poor temperature resistance (≤ 90 ℃).
6.Hydraulic and control systems
Hydraulic system: Pressure stability is essential, the diaphragm filter press needs to ensure that the pressing pressure is up to standard (usually 0.8-2 MPa), it is recommended to choose a well-known brand hydraulic pump (such as Rexroth).
Control system: PLC control can realize automatic program operation, with touch screen to facilitate parameter adjustment and fault alarm, reducing the difficulty of operation.
Comprehensive cost and after-sales service: taking into account short-term investment and long-term operation and maintenance
7.Equipment procurement costs
Different models have large price differences: under the same filtration area, the diaphragm filter press is 30% -50% more expensive than the chamber filter press, and the fully automatic model is more than 50% more expensive than the semi-automatic model.
Avoid over-selection: Select the filter area according to actual needs, and reserve 10% -20% of the margin. There is no need to pursue "large and complete".
8.Operation and maintenance costs
Consumables replacement: filter cloth (life of about 3-6 months), hydraulic oil (annual replacement), diaphragm (life of 2-3 years) are the main consumables, and the processing cost per ton needs to be calculated.
Energy consumption: The diaphragm filter press has a high energy consumption during the pressing stage, and the belt filter press requires continuous power, which needs to be evaluated in combination with local electricity prices.
9.Manufacturer strength and after-sales service
Preference is given to manufacturers with rich industry experience (such as Jingjin Environmental Protection, Zhongda Bellette), who can provide material testing and customized solutions.
After-sales guarantee: It is necessary to clarify the installation and commissioning, operator training, and supply cycle of wearing parts (local service points are recommended) to avoid long-term downtime after equipment failure.
Fifth. Reference to industry cases and test data: reducing the risk of selection
On-site inspection: visit the equipment operation of users in the same industry to understand the actual treatment effect (such as filter cake moisture content, filtrate clarity) and operation and maintenance feedback.
Material test: Send the materials to be processed to the manufacturer for a small test to obtain key data such as filtration time and moisture content of the filter cake as the basis for selection.
Selection steps to sort out
10.Analyze material characteristics (composition, concentration, corrosiveness, temperature) and filtration targets (moisture content, clarity).
11.Determine the type of equipment (chamber/diaphragm/belt) and the degree of automation to match the processing capacity requirements.
12.Calculate the filter area, filter plate specifications, and confirm the core configuration (filter cloth material, hydraulic system).
13.Compare quotations from multiple manufacturers to evaluate procurement costs, consumables costs, and after-sales guarantees.
14.Verify the suitability of the equipment through on-site inspections and material tests, and finalize the plan.
Through the system analysis of the above dimensions, the selection deviation can be greatly reduced, ensuring the efficient and stable operation of the filter press during production, and at the same time controlling the comprehensive cost.
