Polymerization Notes PDF

# Polymerization Notes ## Prawdown - 3,000 in reactor before you start the VAZO - 13,000 full reaction - VAZO should spin for a minimum of 30 minutes ## Catalyst Mix Times - VAZO ~ 75°C or below - AZDN - 5 minutes - VERSENEX - 80 - 3 minutes - circulating agent - HYPO - 5 minutes - JA-044-5 minut...

# Polymerization Notes ## Prawdown - 3,000 in reactor before you start the VAZO - 13,000 full reaction - VAZO should spin for a minimum of 30 minutes ## Catalyst Mix Times - VAZO ~ 75°C or below - AZDN - 5 minutes - VERSENEX - 80 - 3 minutes - circulating agent - HYPO - 5 minutes - JA-044-5 minute - thermal catalyst - Sodium Persulfate - 5 minutes - TBHP - 30 seconds - Mohr’s salt - min - reducer - VAZO - thermal catalyst - MBA - branching agent - HYPO - UL molecular weight controlled by HYPO viscosity - Each polymer we make has a different molecular weight - We use HYPO to regulate the molecular weight for a product and reduce air in solutions - DTANK 26,000 KGS - SPS - SNF Connect ## Redox Reactions - Redox reactions are used to initiate the polymerization - Redox reactions require the addition of an oxidizer and a reducer ##### Redox Package - VERSENEX - TBHP/ Sodium Persulfate - Mott's Salt ## Thermal Degradation - thermal catalyst must be stored in cold storage to keep them chemically stable - Thermal catalyst not kept in cold storage begins to degrade and form free radicals - byproduct of the degradation of VAZO-64 is TMSN (tetramethyl succinonitrile) and is highly toxic - Thermal degradation accelerates the reaction to completion - without thermal catalyst to accelerate the reaction the UL viscosity would build very slowly and too large - so large as to degrade solubility - Different thermal catalyst degrade at different temperatures and react for a different amount of time ### Steps of Polymerization - **initiation** - initiation occurs when the reducer from redox is added to the monomer solution - **propagation** - chains will continue, thermal catalyst / chain transfer agent drives the propagation step - **termination** - 3 causes - absence of monomer - disproportionation - when another free radical attaches the end of the polymer chain - combination - when 2 chains with free radicals combine ## Auto initiation - Can happen if hot gel is left over from the last reaction - If the solution is not at the set point in the dissolution tank during the transfer to the reactor - If there is left over catalyst in the reactor during the drawdown ## Sparging - Polymerization - Sparging is a very critical factor in making in-spec polymer - Sparging is the injection of nitrogen at the base of the reactor to displace oxygen and dissolve it in the polyacrylamide solution - Oxygen is an oxidizer and will inhibit the redox reaction from occurring - Oxygen inhibits polymerization ## Sparge Pressure - Too low of a sparge pressure will result in not enough oxygen being removed from the basin during the set sparge time - This will cause the reaction to be slow to start and will result in an erratic reaction rate - Too high of a sparge rate will result in poor catalyst mixing and erratic curves, resulting in low product quality ## Chelating Agents - VERSENEX 80 can also be used as a catalyst if a large amount is added to a reaction - Excess VERSENEX 80 will chelate all the copper and ion - Chelated iron is much more reactive than unchelated iron and will accelerate the reaction - VERSENEX 80 has the largest affinity for copper - VERSENEX 80 also has an affinity for iron which is used to start the reaction - To keep the iron free and available for free radical formation, the correct amount of VERSENEX 80 is needed ## Branching and Crosslinking - Branching increases molecular weight without increasing the viscosity - MBA - Certain applications can benefit from this characteristic - Branched products still have good solubility - Cross linking is extreme branching that decreases solubility - Cross linking is not desired and should be avoided ## Product Solubility - Solubility is a measure of a polymer's ability to dissolve in water - The primary reason for poor solubility is excessive temperatures in the dryer and during polymerization in the reactor ## Hydrolysis - Hydrolysis is a chemical reaction where water reacts with another substance to form two or more new substances - In polyacrylamide production, hydrolysis occurs when the neutral amine group on the polymer chain is converted to an anionic acrylic acid tail, giving the chain a negative charge - The more hydrolysis that occurs, the higher the charge of the polymer chain - We use CAUSTIC for hydrolysis in our reaction - Temperature of the aqueous monomer during the addition of caustic shoots up so we must make sure to leave the heat exchanger running and not allow the temperature to rise above 12°C - Hydrolysis occurs more in lower anionic products causing a blue/green tint ## Kinetics - The rate of temperature vs time - Measured on an x-y chart ### Temperature - Most reaction start at 0°C and heat up to 75 - 100°C - Some products are initiated at higher temperatures, but never above 20°C - If the reaction does not reach a high enough temperature, there will be left over monomer in the form of a liquid - Federal regulations will not allow the sale of a product with a monomer content above 1000ppm - A reaction that rises above 100°C will cause the water in the reaction to convert to steam and expand the gel into the vent line - This should be avoided as much as possible - If this occurs, check the dissolution thank charge and catalyst package - Reactions can take from 30 minutes to over 3 hours to run - The amount of time it takes will depend on the molecular weight of the product - Reactions that run too quickly will likely have a low UL viscosity (off spec) - Reactions that run too long will likely not reach a high enough temperature and have a high monomer content ## Free Monomer - "free monomer" are the unreacted or unpolymerized monomer molecules that are used to make polyacrylamide gel. - Free monomer is the measure of the amount of acrylamide that has not been converted into polyacrylamide - Free monomer normally happens when the plants have a leaking drain valve ## Reactor - Reactors are vessels where the liquid monomers are charged and are mixed into polymer gel. - Polymerization is the process of making gel - Polymerization begins when the polymerizer removes the oxygen and adds the catalyst - We sell products based on the length of the resulting polymer chains and the charge of the chains - Longer the polymer chains, the harder it is to dry the polymer without causing solubility problems ## Reactor work - The polymerizer fills the reactor with: - Acrylamide - Acrylic acid - Water - Additives - pH adjusters - Monomer - This mix is polymerized by sparging with nitrogen and by the addition of catalyst - Heat is released as monomers react to form polymer chains - This heat makes the gel hotter - The mixture starts at the freezing point of water (0°C) and can peak out near the boiling point of water (100°C) - The primary characteristics of the product we are concerned with are charge and molecular weight (chain length) - The charge is created in polymerization by adding acrylic acid or cat monomer and the molecular weight is increased by decreasing the amount of catalyst and chain transfer agent - Tube reactors are dumped by pressurizing the reactor and forcing the gel through a discharge pipe - * ## Reactor Trouble Shooting - The reactors are lined with a Teflon-like coating or they are electro-polished - If the gel will not dump and the lubrication is good, the liners may need to be changed - If the reactor peaks at too high of a temperature, the cause could be too much monomer and not enough water - Or the reaction could have been stated at too high a temperature - If the batch peaks above the boiling point of water, the gel can be forced violently out of the reactor - Different temps between reactor temp probe could be because of a heat or bad probe ## What to do when a bad reaction is detected - Get DTank sample to poly team for analysis ## Gel Hopper's - The gel hopper is used to maintain a constant flow of product to the granulator - The product is gravity-fed to the dosing screw and is then pushed into the granulator through the action of the screw - The gel hopper is set to maintain a consistent weight of product on the dosing screw - This set point determines when more product should be added to the hopper - When the gel hopper dips below the set point, the automatic sequences within the DCS will begin the process of filling the gel hopper back up - Safety concerns: follow confined space procedures if you enter the gel hopper - Trouble shooting issues: If the load cells on the gel hopper are malfunctioning, the DCS will not have a correct weight and this will initiate the process of filling the gel hopper ## Pre-Grinder - The primary purpose of pre-grinding is to tear the gel into smaller pieces so that the feed will be consistent - If the feed to the granulator is not consistent, the flow through the dryer will not be consistent - This will cause non-uniform drying - The pregrinder is also used to post-treat gel, blend dust, and rework product ### Pregrinder - How it works? 5 Screws: - VIA, VI2, VI3, VI4, VI5 - the pre-grinder tears the gel through the use of screws. The weight of the gel forces it against the screws. - Screws work best when the gel is hot, colder the gel, the more difficult it is to pre-grind - Products like 934SH and 923SH grind very easy, while low UL products like VLM and BPM are more difficult to grid - Very high cationic products can be difficult to grind due to stickiness of the product ## Pre-Grinder Trouble Shooting - If a product that is normally easy to pre-grind will not grind there may be a problem with the gel - If the gel is hard to grid, the UL may be too high - If the gel lays flat the UL may be too low - Gel enters the pre-grinder through the reactors, once the gel has finished reacting and moved out, it is held in the reactor to reduce the unreacted acrylamide monomer - The gel is dumped by hydraulic cylinders for cubic reactors or by pressure in the tube reactors - When the gel is dumped, the screw should be turning forward - This helps to pull the gel out and reduce the strain on the gear motors - * ### Pre-Grinder - cont. - A grinding aid, Lubchopnos PK 455 is added to many products to make the gel easier to cut - The first half of the surfactant is added directly to the screws before the gel is dumped - Once the screws have been coated, the gel can now be dumped - After the gel is dumped, it is run forward for 20 minutes - After grinding for 20 minutes, the gel is reversed, when the gel has been pulled back, the second half of the surfactant is is added - Some products do not require surfactants because they pre-grind easily - Adding too much surfactant can cause the gel to become too fine and will plug the granulator - Surfactant helps to make the gel less sticky because the hydrophilic end of the surfactant is oriented out - The lipophilic end keeps the gel from sticking to surfaces and to itself - The first half of the treatment is added when the gel is pulled back - The post treatment is MBS for cationics and sodium sulfite for anionics - We also use sodium sulfate in blending, this will not work as a post treatment additive - The post treatment reacts with the monomer remaining in the gel - For the post treatment to be effective, it must be evenly spread over the gel and then well mixed into the gel - The second half of the post treatment is added once the gel is returned forward - The gel is then allowed to pre-grind for another 10 - 15 minutes - The better the post-treatment is mixed into the gel, the more effective it will be at lowering the monomer - The amount of post-treatment will be listed on the conditions sheet and written on the pregrinder board in the control room - Some products are not post-treated because it causes too great of a loss of UL - * ### Pre-Grinder (Cont.) - monosodium phosphate is also added to the pre-grinder - The monosodium phosphate helps to reduce corrosion which can lead to specks in the gel - The monosodium phosphate is sometimes placed directly on the screws if there a lot of specks - Monosodium phosphate is added at 0.1% based on the weight of the gel - 6 kg of monosodium phosphate would be needed for a 6,000 kg batch - Operator should check to make sure the gel is grinding and moving evenly - Gel can topple out on some products when it is run forward for too long - Gel can also get hung up and not move uniformly - Some products require more attention than others ## Materials - Span 80 - Tuelen 80 - VAZO pot - PK 455 - S275 - LP3 - LPA OIC - PPEOIL - GRZ - LPLH - steam jacket - 7- Post hydro blender - cyclone - sprayed with caustic coming from GR1 - R9 temperatur - 95°C before boiling point - Caustic - SALT ## Oil - 6010 - LPA - 25-90 - 5275 - 1090-12010 - PK 455 - CIEX - granulator oil tank - C2 - screw lubrication oil tank - C3 Ex - post hydro oil tank ## Hypo - 20 mililiters in VAZO pot of Span 80/ Tween ### Hypo - Reaction Curve - Slower reaction curve indicates higher HYPO weight - Faster reaction curve indicates lower HYPO weight - Higher HYPO lower molecular weight - Lower HYPO higher molecular weight - Viscosity - measurement of the thickness of a solution, which correlates to a polymer molecular weight ## Charges - All neutral, anionic - LPI, LPZ - cover acrylic acid gives a charge - Acrylamide - neutral - Caustic - LP3 gives a charge - Acetic - keep acidity low ## Redox 2 - VERSENEX - RO Water? - Reverse osmosis water been thru purification process, contains no minerals - TBHP/ Persulfate - therefore catalyst will not be able to react - Mott's SALT ## Salt Concentration - Obtain 500 mL beaver from lab, place on scale - Zero out - Take beaver to storage tank, flush line for 5 seconds - Get sample of 500 mL exactly - Weigh on scale the 1 by 500 to get specific gravity - Use chart to determine solution ## LP1/LP2 Diagram: **Process water** - 3 min - Acrylamide (3) - 3 min - Urea - 3 min - Acetic Acid - 5 min - ATN (glycol) - 5 min - Acrylic Acid (glycol) - 5 min - Caustic - 5 min - SALT - 10 min - D-Tonk (glycol) - 2°C - Flow meter (FM) - Centrifugal pump - 75-100°C - US - 5 minutes - Sparges (ARX) - 10 minutes - HS - 5 screws - GRI - 5 min - 5 minutes - Versene (atomizer) - 5 minutes - 5 minutes - CIEX (Chelating agent) - 5 minutes - Thermo Catalyst (atomizer) - 5 minutes - Transfer Fons (2) (BR) - 1- 2 minutes - 5 minutes - Hypo (molecular weight) - 5 minutes - VA-044 (bridge redox catalyst to VAZO) - 30 seconds - Persulfate - 1 minute - TBHP (oxidizer) - 1 minute - Mott's SALT - 1 minute - Initiater - 28-30% Cyclones - 13 screws - 10-12010 - Diffusional Paddle - 52 - 2-3 seconds - 9-1090 - Cooling Paddle - 53 - 0.5- 3 seconds - evaporative paddle - Cyclone ## LP3 Diagram - Water - Acrylamide - Urea - Acetic Acid - D-Tank - Caustic (glycol) - SALT - ATN - Flow meter (FM) - Centrifugal pump - Sparges (PG) - 12-15010 (diffusional) - 4 screws - transfer screw - 52 - fluidized screw - 5- screws - VI - GR1- Atomizer - Transfer Fons (2) - 5- screws - VS - Hydro (molecular weight) - 5- screws - VI7 - GRZ- Atomizer - 5 minutes - 5 minutes - Chelating agent - Transfer Fons (2 minutes) - 5 minutes - BR1 - GRZ - Atomizer - BR2 - 5 minutes - Transfer Fons 2 - Cyclone - Cyclone ## Reaction Curve Polymerization Steps - **initiation** - occurs when the reducer from the redox package is added to the monomer solution - **propagation** - the thermal catalyst and chain transfer agent drive the propagation step - **termination** - last free radical is destroyed or out of monomer ## Hydrometer - Used to measure the oil concentration (%) - Screen for GR1 in LP3 + Ppal is 10 microns / 6 microns for LP1/LP2 ## Crystalization Unit - PSM - sign in sheet, contractar won't work - Clipboard on table, for sucking vapors to scrubber - Scrubber - captures ammonia from M1, R9, GRZ, and dryer - vent goes into server - Ammonia - high pH, volatile gas, low pH solution captures ammonia - Recirculate through demister to create rain showers - Ammonia sulfate solution - Water droplets capture ammonia vapors knockdown to bottom of scrubber + sulfuric acid - Density in scrubber solution reaches 1.19-1.21, transfer to slurry tank after outside operator checks pH - 2- 3 slurry tanks - 60 transfers slurry to mother liquor tank - 85010 - 33,000 KGS - Manual pH slurry and mother liquor tank - Catena sample, check pH, add ammonium hydroxide as needed to achieve pH of 6.0 - 7.0 - Every addition to mother liquor tank, do a water purge - On slurry tank page, flushes slurry tank to mother liquor tank - Runs process water will push any additional ammonium hydroxide / slurry into mother liquor tank - Check P - After mother liquor tank, if crystalizing, send to crystalizer, if not, send to truck tank to load into truck ## Moisture - Every 2 hours - 934 BPmOL - 1945 BPmoic - MBA ## Diagram of a Single Reactor: - FM - flow meter - T RX - sparges (TRX or ARX) - HS - sparges - GR1 - screws - 5 Screws - Connections - VR1- Screws ## Diagram of a Single Cyclone & Sparge: - 5 screws - connections - VS - screws - VI7 - screws - G1 - Atomizer - GRZ - Atomizer - PG - sparges ## Diagram of Multiple Reactors: - CIEX - atomizer (Chelating Agent) - BR - transfer fons