Filter Press Pilot Testing: A Comprehensive Guide

Introduction

Welcome to our comprehensive guide on filter press pilot testing! If you're a business professional in need of a reliable filtration solution, this guide is for you. We'll walk you through the different types of filter presses and the general testing process to help you understand how pilot testing can benefit your operations. Whether you're interested in the HPL300, HPL470, or HPL500 pilot filter presses, we've got you covered. So let's dive in and explore the world of filter press pilot testing!

Description of Equipment and Test Outline for Pilot Filter Presses

Types of filter presses

The HPL300, HPL470, and HPL500 pilot filter presses are "sidebar" filter presses each with a manual hydraulic pump. The filter press consists of a frame, hydraulic system, filter plates with filter cloths. The HPL500 can use either 470 mm x 470 mm filter plates (using an adapter plate) or 500 mm x 500 mm filter plates. The HPL470 can only use 470 mm x 470 mm plates. The HPL300 uses 300 mm x 300 mm. Other equipment needed for a test includes pumps, and mixing tanks with mixers.

General testing process

A filter press is a piece of equipment used in liquid/solid separation. It separates liquids and solids using pressure filtration, where a slurry is pumped into the filter press and dewatered under pressure. The filter press is designed based on the volume and type of slurry that needs to be dewatered. There are different types of filter presses available, including sidebar automatic, manual overhead, automatic dual overhead beam, stainless steel clad, explosion-proof filter presses, vacuum filter presses, and hand filter presses.

The general testing process for pilot filter presses involves the following steps:

1. Install the cloth on the filter plates and put the plates in the filter press frame.
2. Close the press and pressurize the hydraulic cylinder to the proper pressure.
3. Calibrate the pumps as required per manufacturer's instructions.
4. Close the press and make sure the closing hydraulic pressure was reached before tightening the locking ring.
5. Close the bottom filtrate valves and open the top filtrate valves.
6. Prepare the slurry as required with chemical conditioners or body feeds.
7. Start the feed pump and any polymer feed pump.
8. Filtrate will be seen coming out the filtrate header after the press has filled.
9. Start timing the run and collecting the filtrate.
10. Note the filtrate volume collected and pressure at designated time intervals.
11. Open the bottom filtrate valves depending on the slurry concentration.
12. Continue the run until the maximum pressure has been reached and the flow rate has reached a certain level.
13. Turn off the pumps and shut all pump suction valves to prevent siphoning.
14. Open the slurry drain valve slowly to vent the pressure on the press.
15. Open the press when the pressure is 0 psig and remove the filter cake.
16. Weigh and take samples of the filter cake for analysis.
17. Observe the cake release and describe the surface condition of the filter cloth.

Details of HPL300, HPL470, and HPL500 pilot filter presses

The HPL470 and HPL500 pilot presses are suitable for both recessed chamber and membrane tests. A recessed chamber test requires the filter press, feed pump(s), and mixing tank with a mixer. A membrane test requires all the equipment needed for a recessed chamber test plus a source of compressed gas for membrane squeeze and the necessary equipment to control the membrane squeeze.

The HPL300 is suitable for recessed chamber tests and basic membrane tests without cake washing.

The goal of filter press pilot testing is to collect the data required to accurately size a full-scale filter press system. The collected data includes cake solids, cake density, total processing time, processing time for each step, slurry feed solids, slurry pH, actual chemical conditioning dosages, and maximum operating pressure for each process step. Additional data that may be collected includes filtrate suspended solids, slurry pH, and specific chemical analysis required by the process.

Filter press pilot testing is an essential step in determining the appropriate filter press equipment and process parameters for efficient and effective liquid/solid separation. It provides valuable information for designing and optimizing filter press systems.

Filter Cloths

Criteria for selecting a cloth

When selecting a filter cloth for your filter press, there are two main criteria to consider: the initial quality of the filtrate and cake release.

For process applications, it is common to prioritize improved initial filtrate quality and accept slightly poorer cake release. On the other hand, for waste applications, it is common to prioritize improved cake release and accept slightly dirty initial filtrate.

It is important to note that the selection of filter cloth is often based on experience and trial and error. Additionally, the chemical compatibility of the fabric material with the slurry should also be considered.

Factors influencing the cloth selection

Chemicals and Filter Aids:

• Chemical conditioning, which improves filtration efficiency, may not be possible in process applications due to the risk of product contamination.
• The chemicals used for chemical conditioning are determined through tests to determine the proper dosages. A commonly used chemical, ferric chloride, has a concentration of 36% and a density of 1.378 gm/ml.

Filter Press Applications:

• Filter presses are used for liquid/solid separation in various industries and applications, including:
  • Food and beverage processing
  • Chemical manufacturing
  • Mining
  • Power generation
  • Aggregates, asphalt, and cement production
  • Steel mills
  • Municipal plants

Customizing A Filter Press for Your Application Needs:

• The design of a filter press depends on factors such as filtration cycle time, required cake dryness, cloth life, and the need for manual or automated plate shifting.
• Other considerations include the overall design, filtration capacity, number of chambers, filter plate size, and materials of construction.
• Additional features/systems, such as automatic plate shifters, cloth washing systems, drip trays, cake shields, and safety light curtains, can also be customized based on specific application needs.

By carefully considering the criteria for selecting a cloth and the factors influencing the cloth selection, you can ensure optimal performance and efficiency of your filter press in your specific application.

Chemicals and Filter Aids

Chemicals used for conditioning

Chemical conditioning plays a crucial role in the filtration process. The chemicals used for conditioning are determined through tests to determine the proper dosage. However, it's important to note that for most process applications, chemical conditioning may not be possible due to the contamination of the product.

One commonly used chemical for conditioning is ferric chloride. Commercially available ferric chloride solutions usually have a concentration of 36% and a density of 1.378 gm/ml. When using ferric chloride and lime for conditioning, it is recommended to add the ferric chloride first and mix well, and then add the lime and mix well.

Another chemical used for conditioning is hydrated lime. It should be made up in a 10% w/w slurry and added to the slurry. The density of the 10% slurry is 1.08 gm/ml.

Use of Ferric chloride

Ferric chloride is often used as a chemical conditioning agent in the filtration process. It is added to the slurry to aid in the separation of solids and liquids. Ferric chloride helps in coagulating and flocculating the particles, making them easier to remove during filtration.

Use of Hydrated lime

Hydrated lime is another chemical commonly used in the filtration process. It is added to the slurry to adjust the pH level and improve the overall efficiency of the filtration. Hydrated lime helps in the coagulation of particles and aids in their removal during filtration.

Application of Filter aids

Filter aids are substances that are added to the slurry to improve the filtration process. They are usually added as slurries, typically at a concentration of 10% w/w. Filter aids help in increasing the porosity of the filter cake, allowing for better filtration efficiency.

Research and development labs often use laboratory filter presses to test the filtration properties of new materials or optimize filtration processes. Quality control labs use them to ensure products meet filtration standards and identify any potential issues. Laboratory filter presses can also be used for small-scale production of products that require solid-liquid separation.

Filter presses are widely used in various industries and applications, including food and beverage processing, chemical manufacturing, mining, power generation, aggregates, asphalt and cement production, steel mills, and municipal plants.

When selecting filter cloths, two criteria to consider are the initial quality of the filtrate and cake release. The chemical compatibility of the fabric material with the slurry is also an important consideration.

In conclusion, chemicals and filter aids play a crucial role in the filtration process. Ferric chloride and hydrated lime are commonly used chemicals for conditioning the slurry. Filter aids are added to improve filtration efficiency by increasing the porosity of the filter cake. Laboratory filter presses are used for research, quality control, and small-scale production, while industrial-scale filter presses are designed for larger-scale filtration applications.

Test Procedure

Slurry and General Preparations

Pressed Pellets:

• Grinding the sample into a fine powder (<75um).
• Mixing the powder with a binding/grinding aid.
• Pressing the mixture in a die at 20-30T to create a homogeneous sample pellet.

Recessed Chamber Test Procedure

1. Install the filter cloth on the filter plates and place them in the filter press frame.
2. Close the press and pressurize the hydraulic cylinder to the proper pressure.
3. Calibrate the pumps according to the manufacturer's instructions.
4. Close the bottom filtrate valves and open the top filtrate valves. Close the air blow inlet valves and wash water inlet valves.
5. Prepare the slurry with chemical conditioners or body feeds.
6. Start the feed pump and any polymer feed pump.
7. Collect the filtrate and start timing the run.
8. At designated time intervals, note the filtrate volume and pressure.
9. Open the bottom filtrate valves based on slurry concentration.
10. Continue the run until maximum pressure is reached and the flow rate is 10-15 l/m2-hr.
11. Turn off the pumps, shut all pump suction valves, and slowly open the slurry drain valve to release pressure.
12. Open the press when the pressure is 0 psig and remove the cake for further analysis.

Calculation of Terminal Filtration Rate

• The terminal filtration rate is calculated by dividing the filtrate volume (in liters) by the run duration (in minutes).
• For example, if the filtrate volume is 17.40 l/hr, the terminal filtration rate would be 0.29 l/min.

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The provided content covers the test procedure for conducting slurry and general preparations, the recessed chamber test procedure, and the calculation of the terminal filtration rate. It explains the steps involved in preparing pressed pellets, conducting the recessed chamber test, and calculating the terminal filtration rate. The content also mentions the importance of sample preparation and the various methods used in powder compacting. Additionally, it briefly discusses pre-shipment testing and the vacuum pumping system.

Membrane Test

The membrane test is an important procedure in pilot filter presses. It follows a similar procedure to the recessed chamber test, but with a few additional steps specific to membrane plates. Here's an overview of the membrane test:

Initial procedure

1. Install the cloth on the filter plates and put them in the filter press frame.
2. Close the press and pressurize the hydraulic cylinder to the proper pressure.
3. Calibrate the pumps according to the manufacturer's instructions.
4. Close the press and ensure that the closing hydraulic pressure is reached before tightening the locking ring.
5. Close the bottom filtrate valves and open the top filtrate valves.
6. Prepare the slurry as required with chemical conditioners or body feeds.
7. Start the feed pump and any polymer feed pump.
8. After the press has filled, collect the filtrate and start timing the run.

Continuation till maximum filtration pressure

9. Note the filtrate volume and pressure at designated time intervals.
10. Open the bottom filtrate valves depending on the slurry concentration.
11. Continue the run until the maximum pressure has been reached and the flow rate has reached the desired level.
12. Turn off the pumps, shut all pump suction valves, and slowly open the slurry drain valve to vent the pressure on the press.
13. Open the press when the pressure is 0 psig and remove and weigh the cake.

Inflation of membrane plates

14. The membrane test initially follows the recessed chamber test procedure steps 1-9 when using center feed membrane plates.
15. If using corner feed membrane plates, none of the filtrate valves are closed, and the slurry feed is on the upper right-hand corner of the headstand, facing the headstand.
16. Select the correct cake thickness for the press and install the head, intermediate, and tail plates, alternating the filtrate drainage ports.
17. Run the filter press in conventional mode with the specified restrictions.

Cake washing process

18. If cake washing is required, set the terminal pressure accordingly.
19. Open all filtrate valves when the press is full.
20. Perform a presqueeze if necessary.
21. Send wash liquor (usually water) from the lower right to upper left, ensuring proper filtrate and feed valve settings.
22. Continue cake washing until the cake is properly washed.
23. Perform a final squeeze and, if necessary, a cake air blow.

Final steps of membrane test

24. Continue filtrate until the maximum filtration pressure is reached and the flow rate has reached the desired level.
25. Shut off the feed pumps and isolation valve.
26. Attach the membrane hoses to the plates and inflate the membranes.
27. If cake washing is done, inflate the membranes to the specified pressure and adjust the filtrate valves accordingly.
28. Continue membrane inflation until the maximum squeeze pressure is reached.
29. If an air blow is done, adjust the filtrate valves accordingly.
30. Once the cycle is over, turn off the gas used to inflate the membranes and vent the membranes.
31. Open the drain and isolation valves to allow the slurry to drain.
32. Release the pressure and open the press for cake release.

The membrane test provides valuable data for accurately sizing a full-scale filter press system. It is important to follow the proper procedures and safety guidelines to ensure successful testing and reliable results.

Safety Issues

Recessed Chamber Safety

High voltage is needed to generate temperatures greater than 500°C. With high voltage comes inherent dangers of electrocution, fire, and severe burns. Make sure the furnace is properly grounded and no loose wires are connected to the furnace, and wear all necessary protective clothing while operating. The furnace program should be stopped, or the furnace shut off before opening the furnace door. Note that material will not always glow or appear hot, but will cause severe burns with improper handling. The elements for the furnaces may be exposed and can be easily damaged if bumped or scraped. They are very expensive to replace. The furnace elements are operated at a high current and can be dangerous if touched.

Membrane Safety

Maintenance of furnace chamber internals should only be conducted using approved confined space entry and electrical lockout procedures. Residual quench gases remaining in the tank even after the door is opened can cause asphyxiation. Particular care should be taken entering furnace chambers after argon has been used as a quench gas. Argon is heavier than air and can remain in low lying areas for some time. It has no discernable odor and there is usually no advanced warning before unconsciousness occurs. Vacuum conditions in a furnace tank are even more lethal. Lockout procedures to prevent furnace operation must be in place before entering any furnace chamber.

Safety in Sintering Furnace

Of all the features a sintering furnace may offer, perhaps the most important one is safety. These furnaces reach extraordinarily high temperatures and use high amperage. Here are some safety measures to consider:

1. Basic Construction: The chamber is manufactured using A36 Grade Steel and built to conform to ASME Code Section 8. It includes a standard double wall design allowing for proper water circulation throughout the main structure and heads.

2. Chamber Door Design: Furnaces are provided with an autoclave-type design with a rotating ring and standard Buna-N type O-rings. Protective shields are provided on the autoclave movement for personnel safety concerns. The door is operated manually and allows the operator to see what is happening as the door is closed.

3. Gas Cooling System: Maintenance of furnace chamber internals should only be conducted using approved confined space entry and electrical lockout procedures. Residual quench gases remaining in the tank even after the door is opened can cause asphyxiation. Particular care should be taken when entering furnace chambers after argon has been used as a quench gas. Argon is heavier than air and can remain in low-lying areas for some time. It has no discernable odor and there is usually no advanced warning before unconsciousness occurs. Vacuum conditions in a furnace tank are even more lethal. Lockout procedures to prevent furnace operation must be in place before entering any furnace chamber.

4. Pyrolysis Plant Safety: One of the drawbacks of a standard glass pressure reactor is the potential explosions due to hard-to-predict excessive internal pressure and lack of relief mechanism. However, with proper safety implementation provided by the manufacturer, the operator can perform most reactions in a safe manner. Advancements in pyrolysis plant technology and industry best practices continually strive to enhance safety standards and minimize risks associated with these facilities.

5. Metal Pressure Reactor Safety: The drawbacks of a metal pressure reactor (bomb) are set-up, maintenance, and corrosiveness.

It is crucial to prioritize safety when operating any type of furnace or reactor. Following proper procedures, using approved safety measures, and staying aware of potential hazards can help prevent accidents and ensure a safe working environment.

Special Notes for the HPL470 and HPL500 Filter Presses

Filter Press Description

The HPL470 and HPL500 filter presses are "sidebar" filter presses with a manual hydraulic pump. They consist of a frame, hydraulic system, and filter plates with filter cloths. The HPL500 can use either 470 mm x 470 mm filter plates (using an adapter plate) or 500 mm x 500 mm filter plates, while the HPL470 can only use 470 mm x 470 mm plates. The HPL300, on the other hand, uses 300 mm x 300 mm plates.

Frame

• Carbon steel frame with sidebars mounted on a skid
• Follower (a.k.a. moveable head) has a moveable extension piece for easier cake discharge
• Extension piece has buttons on both ends to ensure proper alignment during closing with the follower and the hydraulic cylinder

Hydraulics – HPL500

• Manual hydraulic hand pump with reservoir and hydraulic cylinder
• Closing force of 400 bar (6000 psig), gauge is in metric units
• Valve on hand pump controls hydraulic fluid flow to the cylinder: closed for extending and open for retracting
• Locking ring on the cylinder mechanically maintains proper press closure; it is tightened after the press has closed to the full hydraulic pressure

Hydraulics – HPL470

• Manual hydraulic hand pump with reservoir and hydraulic cylinder
• Closing force of 4000 psig
• Valve on hand pump controls hydraulic fluid flow to the cylinder: closed for extending and open for retracting
• Locking ring on the cylinder mechanically maintains proper press closure; the hydraulic pressure needs to be periodically monitored and maintained during a run

Frontal Piping

• Bolt-on headers
• Center feed and four corner filtrate outlets
• For corner feed membrane, ignore center feed and use upper right-hand filtrate port (facing the headstand)

Press Operation

Recessed Chamber Plates

Description

• Standard center feed recessed chamber filter plates
• Cloths are barrel-neck type and held in place by cloth ties

Installation

• Place the plates in the press in the correct order
• Maximum of 4 chambers (5 plates) can be used
• Additional spacer plates can be installed behind the end plate if the hydraulic cylinder strokes out

Additional Equipment Needed for Testing

• Pumps and mixing tanks with mixers are required for testing with the HPL300, HPL470, and HPL500 pilot filter presses
• Two basic filter press configurations: recessed chamber and membrane
• Both HPL470 and HPL500 are suitable for testing in both configurations
• A recessed chamber test requires the filter press, feed pump(s), and mixing tank with a mixer
• A membrane test requires all the equipment needed for a recessed chamber test plus a source of compressed gas for membrane squeeze and the necessary equipment to control the membrane squeeze
• The HPL300 is suitable for recessed chamber tests and basic membrane tests without cake washing

Press Operation

Recessed Chamber Plates

The press operation for recessed chamber plates involves the following steps:

1. Install the cloth on the filter plates and put them in the filter press frame.
2. Close the press and pressurize the hydraulic cylinder to the proper pressure.
3. Prepare the slurry with chemical conditioners or body feeds.
4. Start the feed pump and any polymer feed pump.
5. Collect the filtrate and note the volume and pressure at designated time intervals.
6. Open the bottom filtrate valves depending on the slurry concentration.
7. Continue the run until the maximum pressure has been reached and the flow rate has reached the desired level.
8. Turn off the pumps and slowly open the slurry drain valve to release the pressure.
9. Open the press and remove the cake for analysis.

Membrane Plate Stack

The membrane plate stack consists of a series of membrane plates and recessed plates. The slurry is fed into the upper right-hand corner of the plates. The membranes are inflated with compressed gas or water. The press is filled conventionally with a maximum feed pressure of 100 psig and a terminal filtration rate of 30-60 l/m2-hr.

Operation of Membrane Press

The operation of a membrane press involves the following steps:

1. Fill the chamber with the slurry.
2. If cake washing, apply presqueeze pressure and send in wash liquor from the lower right to upper left.
3. Open all filtrate valves when the press is full.
4. Perform final squeeze and optional cake air blow in the opposite direction of the cake wash.
5. Continue with optional steps such as membrane squeeze and air blow down.
6. Open the press, remove the filter cake, and take cake samples.

How does a rubber laboratory press work?

During the operation of a rubber laboratory press, the hot plate heats up, causing the rubber molecules to crosslink and form a mesh structure. The hydraulic cylinder applies pressure to shape the rubber and eliminate air bubbles. The press ensures a fine and close organizational structure of the rubber. It also prevents overflow, lack of glue, and sponge-like openings.

Working principle of a laboratory press

In a laboratory press, the hot plate heats up the rubber, making it soft and causing moisture and volatile matter to gasify. The hydraulic cylinder applies enough pressure to mold the rubber and create a fine and close organizational structure. The pressure also prevents overflow and ensures proper adhesion.

Overall, there are two basic filter press configurations: recessed chamber and membrane. The HPL470 and HPL500 pilot presses are suitable for both configurations. The HPL300 is suitable for recessed chamber tests and basic membrane tests.

Conclusion

In conclusion, pilot testing for filter presses is a crucial step in determining the effectiveness and efficiency of the equipment. By carefully selecting the appropriate filter cloth and chemicals, and following the recommended test procedures, businesses can optimize their filtration processes and achieve desired results. It is important to prioritize safety measures, especially when dealing with recessed chamber and membrane presses. The HPL470 and HPL500 filter presses have their own unique features that should be taken into consideration during operation. Overall, pilot testing provides valuable insights and data that can help businesses make informed decisions when it comes to filter press selection and operation.

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