Podcast
Questions and Answers
What is the purpose of oil in the reactor system?
What is the purpose of oil in the reactor system?
What type of reactors are used in the Plaquemine plant?
What type of reactors are used in the Plaquemine plant?
Which of the following is an example of a reducing agent?
Which of the following is an example of a reducing agent?
What happens when oxidizing and reducing catalysts are mixed together?
What happens when oxidizing and reducing catalysts are mixed together?
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What is the color designated for crosslinkers in the polymerization table?
What is the color designated for crosslinkers in the polymerization table?
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Which of the following categories does Ammonium Persulfate belong to?
Which of the following categories does Ammonium Persulfate belong to?
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What is the consequence of mixing oxidizers with reducers outside of the reactor?
What is the consequence of mixing oxidizers with reducers outside of the reactor?
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What is one of the main consequences of inadequate housekeeping while handling catalysts?
What is one of the main consequences of inadequate housekeeping while handling catalysts?
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Which catalyst is primarily used as a reducer in redox reactions?
Which catalyst is primarily used as a reducer in redox reactions?
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In the Dissolution Tank to Reactor Draw Down diagram, what is the role of the flow meter?
In the Dissolution Tank to Reactor Draw Down diagram, what is the role of the flow meter?
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What must be done to thermal catalysts to maintain their stability?
What must be done to thermal catalysts to maintain their stability?
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What happens when thermal catalysts degrade?
What happens when thermal catalysts degrade?
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Which step of polymerization involves creating a free radical on the end of a polymer chain?
Which step of polymerization involves creating a free radical on the end of a polymer chain?
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What is the role of chain transfer agents in polymerization?
What is the role of chain transfer agents in polymerization?
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What is a byproduct of the degradation of Vazo64?
What is a byproduct of the degradation of Vazo64?
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Which of the following steps in polymerization directly follows initiation?
Which of the following steps in polymerization directly follows initiation?
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What happens if the sparge pressure or flow-rate is too low?
What happens if the sparge pressure or flow-rate is too low?
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What is one consequence of a high sparge rate?
What is one consequence of a high sparge rate?
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What phenomenon may occur if there are leaks in the nitrogen lines?
What phenomenon may occur if there are leaks in the nitrogen lines?
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At what oxygen concentration level might convulsive movements occur?
At what oxygen concentration level might convulsive movements occur?
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Which of the following is a symptom of oxygen levels between 10-14%?
Which of the following is a symptom of oxygen levels between 10-14%?
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What is the most significant risk indicated for nitrogen exposure?
What is the most significant risk indicated for nitrogen exposure?
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Which of the following is NOT a symptom of nitrogen over-exposure?
Which of the following is NOT a symptom of nitrogen over-exposure?
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What effect can poor ventilation in a space lead to when nitrogen is released?
What effect can poor ventilation in a space lead to when nitrogen is released?
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What is the primary purpose of pre-grinding?
What is the primary purpose of pre-grinding?
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Which gel characteristics affect the pre-grinding process?
Which gel characteristics affect the pre-grinding process?
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What can happen if the feed to the granulator is inconsistent?
What can happen if the feed to the granulator is inconsistent?
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What is added to the gel to make it easier to cut during pre-grinding?
What is added to the gel to make it easier to cut during pre-grinding?
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What happens when the gel is dumped into the pre-grinder?
What happens when the gel is dumped into the pre-grinder?
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Which product types could be more difficult to grind?
Which product types could be more difficult to grind?
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What could indicate a problem with the gel during pre-grinding?
What could indicate a problem with the gel during pre-grinding?
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What could occur if too much surfactant is added during pre-grinding?
What could occur if too much surfactant is added during pre-grinding?
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What is the main function of a centrifugal fan?
What is the main function of a centrifugal fan?
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Which type of impeller can move both air and powder/gel?
Which type of impeller can move both air and powder/gel?
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What could cause a centrifugal fan to be out of balance?
What could cause a centrifugal fan to be out of balance?
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What is a key feature of closed impellers?
What is a key feature of closed impellers?
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Which type of fan is specifically used to convey product from the granulator to the dryer?
Which type of fan is specifically used to convey product from the granulator to the dryer?
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What impact does a worn impeller have on a centrifugal fan?
What impact does a worn impeller have on a centrifugal fan?
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What is necessary for maintaining good suction in a fan?
What is necessary for maintaining good suction in a fan?
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Which factor does NOT contribute to a fan plugging?
Which factor does NOT contribute to a fan plugging?
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What is the purpose of using a belt tensioner after installing belts?
What is the purpose of using a belt tensioner after installing belts?
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What should be included in the safe permit’s scope of work regarding belt replacement?
What should be included in the safe permit’s scope of work regarding belt replacement?
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Why is it important to witness maintenance tasks being performed?
Why is it important to witness maintenance tasks being performed?
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What equipment should laser alignment be used on?
What equipment should laser alignment be used on?
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What role does water play in polymerization?
What role does water play in polymerization?
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Where does the majority of the water in the acrylamide solution originate from?
Where does the majority of the water in the acrylamide solution originate from?
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Why is dry acrylamide not typically used?
Why is dry acrylamide not typically used?
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What can happen if water is not added during polymerization?
What can happen if water is not added during polymerization?
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Study Notes
Outside Operator Training
- Walking out the job is the responsibility of both the permit writer (usually an operator) and permit approver (usually the shift supervisor)
- If a job scope changes, the permit writer must get approval from the permit acceptor before permitting the work
- A review of the job, LOTO, and permit must be completed before scope changes
- Board operators should not write permits for jobs in the field that another operator is responsible for
- Permit approvers (not permit writers) are ultimately responsible for the permit being sufficient for the work
PPE Matrix
- This is a table that lists the required personal protective equipment (PPE) for various tasks in a powder plant
- It includes a variety of PPE, including respirators, eye protection, body protection, hand protection, and foot protection
- The table allows users to quickly determine the appropriate protection for a given task
- Safety data is provided in a matrix format
Plant Safety - Slips
- Emphasize the slipperiness of the product when it comes in contact with water
- Avoid puddles and walk on the driest surface possible
- Address wet spots quickly to prevent accidents
- Be aware that gratings can be slippery and step over them
- Keep shoes clean to prevent slipping hazards, especially on surfaces with moisture
Plant Safety - Slips (One Point Lesson)
- Five SNF operators and one Emulsions employee, and one contract employee fell in February 2020 due to areas with residual PAM powder and that had gotten wet.
- Barricade tape and overspray should cover the affected areas
- Workers need to avoid the area when wet and should use safety observers
- Use of safety procedures for slip prevention is vital.
Working in Liquids
- Notify Supervisor if you need to work in a liquid environment.
- Ensure the area is properly barricaded and required precautions are taken
- Chemical boots are required, not leather shoes
- Clean boots after completing the work.
Barricade Tapes
- Yellow caution tape indicates a low-degree safety concern, such as hoses, noise, heavy equipment, etc.
- Red danger tape indicates an immediate or high-risk safety concern, such as overhead loads, work at heights, etc.
LOTO and Barricade Tags
- Safety department has tags for LOTO and barricades.
- Barrier tag gives context about the reason for the barricade and who to contact if needed.
- Tags help with task-specific LOTO
Quarterly Inspection Color Code
- Colored tape or tie wraps indicate inspection requirements for specific equipment at the beginning of each quarter
- Items such as GFCI's, portable equipment, rigging and slinging equipment, ladders, hoists, power strips, and welding leads are examples checked.
- Color codes are used to differentiate inspection by quarter.
Dissolution Tanks
- Confirm with the board operator that the tank is ready for additions
- Add each raw material in the correct order: water, acrylamide, urea, acrylic acid, caustic, and salt (if applicable)
- Keep manual valves open only when adding raw materials
Dissolution Tank Ingredients
- Water (solvent)
- Acrylamide (monomer)
- Acrylic Acid or Sodium AMPS (monomer)
- ATN (ATBS 50) (monomer)
- Sodium Hydroxide (caustic) (pH Adj.)
- Other Additives: Urea, Ammonium Sulfate, Salt
Polymer/Polyacrylamide
- Mono = one, Poly = many
- Polymer = many -mers
- Polyacrylamide = Many acrylamide monomers (charged using Acrylic Acid)
Monomers
- Acrylamide - Neutral Backbone
- Acrylic Acid - Anionic Backbone
- Sodium AMPS (JMS50) - Anionic Backbone
- All are dissolved in water and charged with Caustic (NaOH)
Flocculation
- Colloid - A substance (e.g., dirt in pond water or fat in milk) microscopically dispersed within another substance.
- Floc - The grouping of the dispersed substance (via polymer) to overcome molecular interactions and settle out of the solution
PolyACM Types & Differences
- Anionic (-) Charge - Acrylic Acid, Sodium AMPS, Acrylamide
- Cationic (+) Charge - Cationic Monomer, Acrylamide
- Nonionic () Neutral Charge - Acrylamide
Raw Material and Hazards
- This section contains details on the hazards associated with various raw materials used in the production process
- Includes details about acute hazards and symptoms for each material
Raw Materials and Hazards - Acrylamide
- Most hazardous in solid form (carcinogen)
- Inhalation: Cough, sore throat, weakness
- Skin: May be absorbed(redness, pain)
- Eyes: Redness, pain
- Ingestion: Abdominal pain, weakness
Raw Materials and Hazards - Urea
- Inhalation: Irritation to the respiratory tract
- Skin: Irritation, redness, itching, pain
- Eyes: Irritation, redness, pain
- Ingestion: Irritation to the gastrointestinal tract, nausea, vomiting, diarrhea
Raw Materials and Hazards - Acrylic Acid
- Inhalation: Cough, sore throat, shortness of breath
- Skin: May be absorbed, redness, blisters, pain
- Eyes: Redness, pain, severe deep burns, loss of vision
- Ingestion is not specifically mentioned
Raw Materials and Hazards - Caustic
- Inhalation: Severe irritation of nose and throat (only if mist or dust)
- Skin: Pain, redness, burns, blistering, severe exposure can cause death
- Eyes: Burns, redness, swelling, pain, blurred vision, permanent damage/blindness
- Ingestion: Burns to lips, tongue, throat, stomach; symptoms include nausea, vomiting, stomach cramps, diarrhea, and can cause death
Raw Materials and Hazards - Salt
- No known hazards
ATN Grades Used in Powders Process
- Plaquemine ATN is in two grades
- XG - highest quality, used for Post-Hydro products
- HQ - lower quality, used for standard products, AN 125SH/VHM, AN 113SH/VHM, AN 118SH/VHM
Inhibitors
- Acrylamide is inhibited by copper and oxygen, which is added during manufacturing.
- Oxygen reacts with free radicals to form stable radicals, preventing the initiation of polymerization reactions.
- MEHQ (hydroquinone monomethyl ether) is another inhibitor used.
Inhibitors (Cationic monomer and acrylic acid)
- Cationic monomer and acrylic acid are inhibited by MEHQ (mono methyl ether of hydroquinone) and oxygen.
- Cationic monomer is also inhibited by Versenex 80.
- MEHQ transfers a hydrogen atom to a free radical which prevents initiation of a polymerization reaction.
Dissolution Tanks
- Images of different components of dissolution tanks (pipes, pumps, valves etc.)
Why Should We Keep Raw Material Valves Closed?
- Excess raw material can accumlate up to 25-30kg.
- The pH of the product is sensitive to propagating polymerization.
- Delays in the process can result in poor reaction and a low yield
- Closing the valves helps maintain a good reaction and quality in the product.
BVE
- BVE is used in the production of A 3338, and more foam is generated.
- A special anti-foam (Sag 30) is used in conjunction with BVE to help reduce foam.
Anti-Foam
- Anti-foam is used to eliminate foam from the dissolution tank before transfer
- Excess anti-foam can slow down heat-ups in the reactor
- Insufficient anti-foam may lead to foam regeneration, and interfere with catalyst mixing
Measurement of Additives in Dissolution Tanks
- Mass flow meters calculate the amount of liquid moving through a pipe
- Pressure transmitters measure the force of solution against a membrane; higher levels mean higher bottom pressure.
- The in-line pH meters on recirculation lines are useful when adding acids or bases to the dissolution tank.
Adjusting pH
- The pH of the dissolution tank should be adjusted carefully for each product type.
- Caustic/Sulfuric acid is used to adjust the pH.
- The amount/concentration of acid is measured precisely to avoid overshooting the target pH
- Supervisor must be notified in case of errors
pH Probe
- pH probes are calibrated using buffer solutions with known pH values.
- Bench top calibration instructions are provided (PAM-COM-005)
Acrylic Acid
- Acrylic acid gives the polymer a negative charge
- Too much acrylic acid leads to high anionicity and too little leads to low anionicity.
Acetic Acid
- Used for pH control in the post-hydro process, this protects anionicity from being adversely affected
Salt Tank
- Oversaturation from too much salt is a particular concern, and accurate records are necessary
- Ensure the agitators in the tank are working to avoid clogging of the pump.
Sampling a Dissolution Tank
- All dissolution tanks must have a retaining sample
- Samples are needed to troubleshoot problems with product quality (polymerization and drying upsets) if samples are not received
- The samples are matched to the corresponding reactor samples to detect off-spec issues
D-Tank Transfer Pump
- Centrifugal pumps transfer aqueous solutions to reactors to prevent damage during high pressure conditions
- Glycol heat exchange is fragile
- Short periods of time without damaging the pump can be used for short periods.
- A motor monitor protects the motor during pump cavitation.
- A low level probe is on the discharge side of the pump to shut off if no level.
Dissolution Tank Temperature
- The dissolution tank is cooled to prevent unwanted auto-polymerization
- The target temperature of the tank is 0 degrees C.
- A temperature difference of -2 degrees C in the tank is equivalent to 0 degrees C in the reactor.
- If the temperature exceeds 15 degrees C an alarm will go off, preventing caustic addition.
- If the temperature exceeds 25 degrees C, the caustic addition will shut off automatically.
Environmental
- Aqueous solutions must be stored in diked areas to control accidental spills and prevent environmental damage
- The finished product is detrimental to aquatic organisms
- Water or condensate (pH 6.0-9.0) in the sump or dike must be neutralized with acid/base, if outside of this range
Rotation Checks
- Mechanics and electricians need training on the proper direction of equipment, which must not be reversed to operations.
- Operations personnel are ultimately responsible for proper direction.
Leak Checks Following Line or Equipment Openings/Breaks
- Equipment should be pressure tested in the shop before installation
- Hazardous material systems (AN, AA, NaOH, Oleum) must be pressurized and leak checked before use
- Develop a contingency plan if this isn't possible, involving PPE and safe monitoring distances
- Non-Haz systems can be pressure checked or monitored, at the discretion of the Supervisor.
Emulsion Management – Empty Drum/Tote
- The Emulsions department manages the empty drum roll-off bins for plastic or metal drums
- The Powders Shift Supervisor coordinates with the Emulsions team on drum usage.
- Drums are checked and the condition is noted for each drum.
Reactor Type
- SNF has two types of reactors for polyacrylamide production.
- The Plaquemine plant uses "Tube Reactors" with electro-polished internal walls.
Oil Reactor Before Drawdown
- Oil prevents gel from sticking to internal reactor parts, preventing contamination
- Oil improves gel draining speed, and reduces equipment strain caused by friction
Dissolution Tank To Reactor Draw Down Diagram
- A flow diagram outlining how substances are moved from a dissolution tank to a reactor
- Fluid flows from the Dissolution Tank to the Reactor. The process uses a flow meter to regulate transfer rate and to maintain a specific temperature
Polymerization Table Color Code
- This is a table outlining the types of polymers and their attributes, which are color-coded by the type of polymer.
Catalyst Handling
- Mixing oxidizing and reducing catalysts results in a violent reaction, which can lead to burns, trauma, and even death
- High standards of care and housekeeping should be maintained when handling catalysts
- Specific safety precautions for each catalyst (e.g., TBHP, Persulfate, MBS, Mohr's Salt, VA-044) should be followed.
What is Hypo Doing?
- Sodium Hypophosphite is a chain transfer agent, creating free radicals that terminate or initiate the polymer chain growth.
- This control of free radicals allows for fine-tuning of the final product's molecular weight
- Faster reaction rates equate to lower hypo weight, and slower rates to higher hypo weight
Hypo (DEA List 1 Chemical)
- Sodium Hypophosphite is used as an emulsifier and stabilizer, meeting Food Chemical Codex guidelines for use in food, beverages, and nutritional supplements.
- This chemical must be kept in a locked cage
Catalyst Storage
- Daily plant operations should only hold a 24-hour supply of catalysts
MBA in A3338
- Too much MBA causes crosslinking, which can lead to a low UL (Ultimate Level) value
- Insufficient MBA leads to problems such as low UL and poor solubility
MBA and MBS Confusion
- MBA, used in A3338, is less common and does not have the strong odor of MBS
Thermo-Catalyst
- Thermal catalysts decompose at temperatures between 30 and 40 degrees C
- These catalysts produce free radicals, initiating further polyacrylamide solution reaction
- Common catalysts include Vazo 67, 64/AIBN, 52, AZDN and ABNR, VA-044
What is Vazo Doing?
- VAZO 64, a thermal catalyst, decomposes above 30° Celcius into free radicals.
- These radicals stimulate polymerisation of the product, generating heat that keeps the reaction proceeding
- The process continues until all monomer has polymerised or runs out and the thermal catalyst is then used up.
What is VA-044 doing?
- VA-044 is another thermal catalyst used for polymization; it performs slightly below 30 degrees C compared to VAZO
- This catalyst functions as a "bridge" between the redox catalysts and VAZO
- It produces free radicals for the reaction process, and is most commonly used to help mitigate stalling/dying before VAZO is used up in higher molecular weight products
Catalyst Mix times
- Mixing times should be followed for various catalysts (AZDN, Versenex 80, Hypo, VA-044, Sodium Persulfate)
- Time limits vary depending on the specific catalyst
- A brownish gel color indicates unreacted catalyst in the reaction.
Catalyst Add Time
- Ensure catalyst is precisely measured and mixed into the solution to ensure uniform mixing
Why do we need to be precise with Hypo weights?
- Different polymers have different molecular weights, and the amount of hypo needed to adjust this is very specific.
- Hypo adjusts the molecular weight needed for a suitable product, and to remove insolubles
I'm done polymerizing my Reactor, Can I discard my catalyst bags?
- Catalyst bags must be emptied and placed into separate waste bags.
- Tied off and properly disposed of in plant trash.
Polymerization Reaction
- Initiator (thermal catalysts, redox),
- Propagation,
- Termination
Redox Reactions
- Primarily used to kick off the polymerization reaction.
- Oxidizers: Sodium Persulfate, Tert-Butyl Peroxide and Potassium Bromate
- Reducers: Sodium Metabisulfite, Sodium Sulfite and Mohr's Salt
Thermal Degradation Reactions
- Vazo67, Vazo64/AIBN, Vazo52, AZDN, ABNR, VA-044 are the main catalysts
- These catalysts are kept in cold storage to maintain chemical stability and extend shelf life up to 3 months
Chain Transfer Agents
- React with the growing polymer chain to create free radicals.
- This termination of the polymer chain initiates the growth of a new chain.
Steps of Polymerization
- Initiation: Free radicals attack C=C bonds in the monomer, creating a free radical
- Propagation: The growing chain continues to add monomers until a stopping agent is introduced
- Termination: The reaction ends when the chain transfer agent is used up or the reactants are used up
Polymerisation-Initiation
- Free radicals attack C=C bonds in the monomer, creating a free radical on the end.
- Initiation occurs when the reducer from the redox package is added to the monomer solution
Polymerization-Propagation
- The newly formed free radical at the end of a monomer attacks the C=C bond of another monomer to extend the chain
- Polymerisation continues until chain transfer agents are used up or the reactants are used up
- Thermal catalysts and chain transfer agents are involved in initiating this step
Polymerisation-Termination
- Reaction ceases when a free radical attacks the end of the polymer chain
- The chain reaction terminates when two free radicals combine
Reaction Curve Polymerization Steps
- A graph demonstrating the temperature variation during various stages of the polymerization process, including initiation, propagation, and termination.
Auto-Initiation
- Auto-initiation may occur if hot gel is left over from a previous reaction.
- Or if the solution is not at the set point in the dissolution tank during transfer to the reactor
- It could also occur if there is leftover catalyst in the reactor during drawdown
Sparging
- Nitrogen is injected into the reactor to remove oxygen and initiate the polymerization process.
- Sparging helps produce a good, even reaction rate.
- Improper sparge pressure or flow rate could lead to poor catalyst mixing, slow starting reactions, and product quality issues
Why Nitrogen is Required?
- Sparging is vital for removing oxygen, an inhibitor, from the solution to start the polymerization process efficiently.
- Too low flow of nitrogen means not enough oxygen removal and the production may be affected
- Too high of a nitrogen flow rate or leaks in the line can cause the production to be slower or a dead batch, due to air entering the system
Nitrogen Hazards
- Asphyxiation is the main hazard associated with an uncontrolled release of Nitrogen
- Prolonged exposure to low levels of oxygen can cause symptoms, such as headaches, ringing in ears, dizziness, etc.
- Symptoms can escalate to: Unconsciousness, nausea, vomiting, depression of senses, and eventually death..
Chelating Agents
- Copper must be removed from acrylamide to control initiation
- Versenex 80 is a chelating agent with high affinity for copper
- Preventing premature initiation and maintaining optimal polymerization reaction
Branching and Cross-linking
- Branching increases the molecular weight without noticeably changing the viscosity
- Certain applications benefit from this characteristic (increased viscosity), but excessive branching or crosslinking in our polymerisation would cause issues
- Crosslinking is a form of extensive branching that will decrease solubility.
Product Solubility
- Excessive temperatures during drying and polymerization can cause crosslinking, reducing solubility
- Primary culprits include extremely high UL values, very high branching concentrations, and significant residual acrylamide buildup
Hydrolysis
- Hydrolysis occurs when water reacts with the neutral amine group in acrylamide, converting it to anionic acrylic acid
- Hydrolysis occurs more in lower anionic products, where over-drying could lead to a blue or green tint
- Controlling the temperature of the aqueous monomer during caustic addition is essential for preventing hydrolysis.
Kinetics
- Kinetics refers to the rate of polymerization, measured by temperature variations over time
- Polymerization needs to reach a high enough temperature without exceeding a safe limit (100°C) to avoid steaming.
- If the temperature is not high enough, the monomer may remain in liquid form exceeding the permitted 1000ppm limit
Kinetics (Time)
- The time it takes for reactions to occur and reach a specific product rate
- Reaction times can range greatly depending on product weight (faster for lower, slower for higher)
- Reactions running too quickly can result in a low UL viscosity (off-spec).
- Reactions running too long may not reach the necessary temperature, resulting in a high monomer content
Free Monomer
- Free monomer is the amount of acrylamide in a product that isn't properly converted into polyacrylamide
- These problems are often due to leaking drain valves.
Molecular Weight
- Molecular mass (m) is the mass of a given molecule measured in unified atomic mass units (u or Da).
- Different isotopes of an element can give different molecular masses for the same compound
Reactor
- Reactors are vessels used to prepare liquid monomers and change them into polymer gel.
- Removal of oxygen and addition of catalyst are key in the polymerization process
Reactor–How does it work?
- Polymerizers mix monomers with water, additives, and pH adjusters to prepare the reaction mixture.
- The reaction starts at freezing point (0°C) and can rise significantly once the reaction begins
- The temperature is monitored and the time for dumping the gel is recorded (peak time)
- The product hold time is pre-determined in the lab and used to determine optimal dumping times
- A 60/30/10 spray on the reactor liner makes gel dumping easier
Reactor – How does the Reactor work? (Continued…)
- To assure good operation, there is a "double-checking" process for operators, checking temperatures and correct reactor selection
- Use of a 60/30/10 spray on the reactor liner helps with making the emptying procedure easier
Reactor Trouble Shooting
- Issues like not properly lubricating the reactor to cause poor discharge, or not having the right temperature could make the product difficult to fully dry.
- Problems such as overheating can cause the gel to be violently forced out, resulting in equipment damage or injury to operators
- An operator checking for leaks in the piping before drawdown can help prevent these types of problems and improve production outcomes
What to Do When Bad/Slow Reaction Detected?
- Notify supervision and Poly Tech immediately for analysis and testing.
- Use the troubleshooting guide for the specific issue
- Follow the facility's bad reaction protocol/management plan, which might include: sucking out the reaction, letting the reactor peak, and separating the gel.
Reactor Safety Concerns
- The extremely hot gel can cause burns or skin irritation.
- Precautions should be taken around the gel since it's dangerous to have it fall on someone
- To avoid oxygen leaks that could cause issues in closed environments, separate and lock-out the nitrogen lines when working inside
Solenoid Control Panel
- Electricians and authorized employees may operate the solenoid control panel
- Ensure the actuators are not in operation before working on the apparatus.
Gel Hoppers
- Maintain consistent flow of product
- Gel is fed to the granulator using gravity
- Load cells measure gel weight to trigger automatic filling and refill sequences
Pre-grinders (Why do we need them?)
- Some plants use pre-grinders to break down the gel into consistent-size pieces.
- This ensures the feed to the granulator is consistent to allow for more efficient processes and prevent future issues.
Pre-grinders (How does it work?)
- Pre-grinders use rotating screws to grind the gel
- The appropriate pre-grinder settings to ensure production quality depend on the type of product
- The lower the gel density, the harder it is to pre-grind
- Issues that lead to abnormal operation may involve the product quality, or a change of temperature.
Pre-grinders - How does it work? (Continued…)
- Lubrhophos PK455 is a grinding aid to help with certain products. The aid must be evenly placed, mixed and spread.
- The first half of the post-treatment additive is applied before the gel is dumped, while the second half is added once the gel is reversed.
- Different products have different treatment levels, as detailed on the conditions sheet.
Pre-Grinder - How does it work? (Continued...)
- Monosodium Phosphate is added in some cases to reduce corrosion and unwanted effects on product.
- The amount is 0.1% relative to the gel weight.
- Dust rework in the pre-grinder usually involves placing dust on top of the gel followed by mixing in water to create a usable gel product.
Pre-Grinder Safety Concerns
- Safety for the personnel working inside the confined space during maintenance and operations.
- Risks of being injured by moving equipment parts.
Granulation (Why do we need the Granulator?)
- Granulation is used to reduce gel size and improve particle uniformity, to ensure even drying of the product.
- Smaller particles have a larger surface area for improved contact with the air, thus better drying.
Granulation (Why do we need the Granulator? – Continued…)
- The Granulator system has two types of blades: fly knives and bed knives, which grind the gel to produce uniformly sized granules
- The granulator has standardized screens that are used to control the size of the finished product, as specified by customer specifications.
Granulation (How can you tell if the blades need to be changed?)
- Performance issues such as product difficulty being pushed through the dryer or chipping can indicate wear
- Excessive gap widths between the fly knives and bed knives may reduce effectiveness for granulation
- Adjusting the gap size is done by moving the bed knives
Granulation – Granulator Screens
- If the granulator screen has a hole or tear then metal will pass through and cause damage to blades.
- The right screen (size) needs to be on the Kason, as different screens are used for different products (e.g., 8mm for some, 10mm for others)
- The screen should be checked monthly for damage.
Granulation – Granulator Screens - How does it work? (Continued…)
- The appropriate grinding aid (Lubrhophos PK455) assists in separating the gel and ensures smooth pre-grinding of products like 934SH or 923SH
- The second half of the post-treatment additive should be added when the gel is reversed. The optimal monomer content is around 1000 ppm.
- The conditions sheet specifies the type and concentration of post-treatment added to each product.
Granulation – Granulator Screens - How does it work? (Continued…)
- Monosodium Phosphate is occasionally used as a grinding aid to reduce corrosion or unwanted specks in the gel.
- The appropriate quantity is typically 0.1% of the gel's weight.
Granulation (Oil Spray Nozzle)
- The oil spray nozzle in the granulator is used to help the cutting process of the gel
- The oil mixture is composed of oil (i.e. LPA210) and surfactant (i.e.S-275) to help maintain consistency for drying
- Proper air pressure is essential for effectively atomizing the oil
Granulation (Oil Spray Nozzle – Continued…)
- The installation of the Nozzle needs to be done correctly, see the PAM-03-205 manual for complete instructions.
- The OPR personnel are responsible for the correct identification and labeling of the lines before, and after, disconnecting the lines.
- The ports for air and oil should be clearly identified and marked before installation.
Oil Tank
- The oil tank is used to mix oil and surfactant to aid in the smooth operation of the granulator.
- The oil and surfactant mixture coats the gel to help prevent stickiness to the equipment.
- The mixture is pumped through the granulator using a spray nozzle.
Oil Mixing
- The oil (and surfactant) needed for each product is found on the dryer condition sheet
- The S-275 is measured volumetrically in totes.
- Air passing through flowmeters may be registered as liquid, leading to inaccuracies in volume measurement. A minimum liquid height in the tote should be the equivalent of about 15".
- Density testing is used to determine the correct amount of S-275 to add to the oil.
Past R-9 Screw Problems
- Gearboxes for the R-9 screws should be the same distance from the tank wall, to prevent gel transfer inefficiency, or damage to supports.
- Alignment of screws is vital to consistent process operation and reported discrepancies during maintenance/operations tasks should be compared.
Oil Tank Safety Concerns
- The oil/surfactant mixture is an irritant and should be handled with care
- The mixture is also flammable.
Span/Tween 80 Additive
- This additive coats Vazo 64 to keep it in a slurry form for efficient reactor transfer.
Surfactant
- Surfactants reduce the surface tension between liquids
- They act as detergents, wetting agents, emulsifiers, or foaming agents
When do we need to pull Granulator Samples?
- Samples are required when products don't meet specific quality control standards (e.g., non-conformance, off-grade product)
- Samples from the granulator, dryer, and other relevant processes are required for analysis and quality control.
How Do We Know a Product is Good for Sale?
- Each product undergoes a specific testing criteria to determine if it meets the required standards
- Key parameters measured are: total solid content, residual acrylamide, insolubles, Brookfield viscosity, filtration quality, %solids, pH, anionicity, etc.
Rx to S1
- A process flow diagram illustrating how materials are transferred from the reactor to the dryer, showing the involved equipment and their respective functions
Now lets reduce the particle size of the polymer
- Product viscosity is improved if the particle size is reduced using the granulator
Drying – Fluidization
- This process of fluffing the product is done to assure even drying
- Air flows through the product in a controlled manner
- Using a vibrator to maintain the product moving is necessary in some fluidized bed dryers
Drying - Tips
- Dryer 2 (Part Two) is controlled by product temperature, while dryer 1 (Part One) can be controlled by either burner or product temperature
- Maintaining a consistent temperature and feed rate is crucial to avoid issues (e.g. over/under-drying)
- Operator should run moisture tests every 2 hours and adjust to maintain consistent operation of the dryers
Gas Train
- Prevents natural gas explosions/asphyxiation hazards at the dryer burners.
- Includes pressure switches to control gas flow, so that the dryer will not run when the gas train is not operational
Gas Train How Does it Work?
- The gas train is a series of valves and safety switches with double block and bleed valves within the system
- In case of a problem, these valves isolate the gas
- The system uses special pilot systems (e.g. an electronic brain box) that also controls the burner system
Gas Train Trouble Shooting
- Troubleshooting steps to identify and correct problems in the gas train system
- Common problems include situations where the burner won't light because of safety mechanisms or issues with gas pressure detection or air flow.
- The importance of working closely with electrical maintenance to diagnose and fix any gas line leaks.
Burners (Why do we need them?)
- Burners use natural gas to create heat for drying
- Efficiently burning the gas ensures maximum heat output with minimal pollutants
Burners (How does it work?)
- Natural gas and airflow mix via openings within the burner pipe, which are often designed for optimal combustion
- Airflow is managed by a large dryer fan and a burner fan, to get the correct ratio of gas-to-air.
- The burner temperature can be tested and adjusted via probes
Burner Trouble Shooting
- Common issues with the burner are often related to the gas train system (e.g. problems with safety systems or flame detection), issues related to faulty gas or air flow can affect the proper operation of the burner system
- Inspect the burners for damaged air shields periodically
Burner Safety Concerns
- The gas train is designed to prevent explosions of gas but the burners can still be hot.
Cyclones (Why do we need them?)
- Cyclones separate particles (product and dust) from the air streams by leveraging centrifugal force
- Products are routed back into the dryers via cyclones, or to the next process stage using the cyclone blower
Cyclones (How do they work?)
- Particles enter the cyclone at a high speed through the inlet, impacting the wall.
- Separation of product stream and air proceeds, with larger and heavier particles directed towards the bottom
- These particles are collected, and the air exits through the outlet
Cyclone Trouble Shooting
- Wet product buildup in the discharge area of the cyclone can lead to plugging
- Cyclones becoming plugged if there isn't enough airflow and may cause a blockage if the fan is not pulling sufficiently.
- It takes more than 10 minutes to clear a plugged cyclone; the system needs to be shut down.
Cyclone Safety Concerns
- Hazards of dusty or wet products hitting the eyes or causing injury to hands/fingers from moving parts/actuated valves/rotary valves
Stacks (Why do we need them?)
- Stacks disperse combustion gases and unreacted monomers from dryers, preventing ground-level pollution.
Stack Process Description
- The stacks exhaust gases from dryers into atmosphere. This is regulated by pre-set permits for particular stack materials
Stack Trouble Shooting
- Discharges of powder, coarse dust, or flakes can cause plugging in the cyclone
- High pressure when loading or unloading the dryers may cause such discharges
- Excessive fluctuations in relative humidity can cause these clogs
Stack Safety Concerns
- Stack water drain totes need to be checked and replaced as they become near full to prevent accidents and spills
Particulate Monitoring Overview
- This system tracks emitted particulate matter, to maintain compliance with permits.
Heat Tracing
- Heat tracing maintains the desired temperature in the lines to prevent freezing or problems due to low temperature.
Stack Monitor Operation
- The monitoring system will collect powder or materials and track and report any excessive airborne emissions into the surrounding atmosphere.
- The system runs in a background active state until a high-pressure controller reaches a high value which then triggers a 5-minute backup timer.
- If the HH value isn't back to normal after 5 minutes, the plant shuts down
Process Alarm Activation Steps
- Obtain new screen and gaskets for any issues
- Have PMO or outside operator remove the locking clasp on the fan's suction side
- Rotate the butterfly nut to release the clasp and separate the pipe connections
- Remove the filter and install a new filter
- Realign the pipe for a tight connection. Re-install the clasp, and tighten the butterfly nut.
- Check the areas around the plant for particulates that came out of the stack, and report concerns immediately.
Alarm
- Visual representation of various alarms on a panel display and their associated values, to aid in problem solving.
- Critical parameters being monitored include the pressures for LP1, LP2 and LP3 and others
Kason
- The Kason is used to separate the oversized product from the remainder of the intended product when exiting a dryer or blender.
- It's used to remove clumps of product
Kason (How does it work?)
- The Kason is a vibration screener with an off-center weight mechanism
- The vibration causes particles to move according to their size, and the larger, heavier particles get rejected or "scalped" from the product stream
Kason Troubleshooting
- An 8-10mm screen is needed at the end of the dryer
- A 2.5-3.5mm screen should be above the bagging/blending machinery
- The screen needs to be monitored monthly for holes or damages to the gasket
- The flow rate below normal will indicate problems associated with the screen getting plugged
Granulator Safety Concerns
- The high-speed turning screws pose the risk of injury to personnel
- The presence of nitrogen poses asphyxiation risks and should be monitored
- Proper lockout/tagout procedures should be followed during maintenance and operations
Drying (The Theory)
- Polymerization with water
- Drying steps using different temperatures to remove water and avoid drying problems
Drying (Temperature)
- Temperature control is a critical aspect of the drying process.
- Burner temperatures need to work synergistically with product temperatures to maintain optimal drying conditions without causing crosslinking.
Drying – Temperature (Continued…)
- Probes are inside the windbox for immediate reading, and in the dryer bed for point in time feedback
- Measurements may need to be taken consistently to account for potential issues such as spikes or inconsistencies
Drying – Level
- Drying rate is maintained by regulating the level of the product in the dryers
- Maintaining consistency allows for proper and controlled drying using optimized temperature and air flow
- If level is too high or too low this could impede drying processes or cause products/products to be out of specification (e.g., re-massed or not adequately dried)
Drying – Feed Rate
- The feed rate is a variable in drying, and needs to be adjusted for different products
- High feed rates are used if the burner is operating fully and lower feed rates are used if the temperatures need adjustment to stay on-line or avoid plugging
- If the feed rate is too slow, the temperature may not fully maximize or be within range; if too fast, there is risk of causing issues due to product being too hot or improperly dried
- Adjusting the feed rate is important in maintaining adequate levels in the dryers.
Drying – Feed Rate (Continued…)
- Product characteristics like molecular weight (e.g., VHM, SH) influence optimal feed rates for different types of product
- Maintain adequate feed rates to maintain consistent dryer temperatures
Drying – Fluidization
- The use of air and mechanical action to maintain consistent product flow
- Maintaining the appropriate levels of air-flow, humidity, and temperature helps ensure proper drying conditions
Drying – Dryer Types (Original Rotary Dryer)
- Rotary dryers use a combination of airflow and mechanical forces to fluff the product for even drying
- Air pressure is created by the dryer fan; air moves through the dryers and air injectors to keep the product moving
Drying – Dryer Types (Fluidized Bed Dryer
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This quiz covers essential concepts related to chemical reactions, catalysts, and polymerization processes. Learn about the roles of various agents, the function of different reactor systems, and the implications of mixing oxidizers with reducers. Test your knowledge and understanding of these fundamental topics in chemistry.
