Powder Process Description Interview Guide

# Powder Process Description ## Intro The Powder's Dept products are based on an Anionic charge and molecular weight, which are determined by the polymer chain length. The product's charge and chain length are created through a polymerization reaction process, which occurs by free-radical generatio...

# Powder Process Description ## Intro The Powder's Dept products are based on an Anionic charge and molecular weight, which are determined by the polymer chain length. The product's charge and chain length are created through a polymerization reaction process, which occurs by free-radical generation. ## Charging the Dissolution Tank Prior to Polymerization, raw material and additives are charged into a dissolution tank. The D-tank is a mixing tank where the ingredients are charged prior to polymerization. A D-tank holds 2 RX's, each with a charge size of 26000kgs. The ingredients and amounts added to the D-tank before polymerization determine the concentration, pH, and during post-hydrolysis, the charge of the polymer. LP1/LP2 have (3) D-tanks and LP3/Lp4 have 4 D-tanks. ### When charging the D-tank - Water is always added first because it acts as a solvent for the other raw materials and as a temperature control by absorbing heat - Next, ACM is added to provide the backbone to the polymer chain. - Then Urea is added to increase the product weight without affecting the UL. - Following that, Acrylic acid is added to produce an anionic charge on the acrylamide backbone. The amount of Acrylic acid added to the D-tank determines the concentration of anionic charge of the polymer. - Caustic (sodium hydroxide) PH adjusters -Acetic acid (Post hydro only) PH adjusters – used so anionicity will not be adversely affected in the post hydro process - Salt if necessary Is used a filler. After the addition of ingredients, the D-tank is then cooled to a -2℃ prior to transferring, which equals 0 degrees C in the reactor after transfer. ## Transferring the Dissolution Tank to the Reactor for Drawdown The liquid monomer solution is transferred from the D-tanks into the reactors. The solution is polymerized by sparging with nitrogen (which displaces the oxygen in the solution) and by the addition of catalyst. A thermal catalyst, chelation agent, chain transfer agent, and redox catalysts are added to the reactor to promote the initiation of the reaction. The catalyst is mixed and charged on a timely basis to assure it mixes properly throughout the reaction before the initiation process. (Mixing too long can cause catalysts to lose effectiveness, which can result in slow heat ups or a dead batch.) Oxygen is an oxidizer and will inhibit the redox reaction from occurring ## Draw Down - **Vazo** - is charged first, having a mixing time of at least 30 mins. Vazo is a thermal catalyst that initiates the reaction, decomposing at 30 degrees C producing free radicals. - **Versenex-** is charged next, having a mixing time of 3 mins. Versenex is a chelating agent that removes copper out of the water and separates the metal ions from the acrylamide polymer. - **Hypo-** is then charged, having a mix time of 5 mins. Hypo is a chain transferring agent that determines the molecular weight of the product. (Controls the UL) - **Sodium Persulfate** - if applicable, Sodium persulfate is charged next, having a mixing time of 5 mins. It's an oxidizer that used in high molecular weight products. While weaker than TBHP, it has better reactivity to finish RX's - **TBHP** - is then charged, having a mixing time of 30 seconds. TBHP is an oxidizer that assists in the redox reaction with Mohr Salt to initiate the reaction by assisting with the generation of free radicals. - **Mohr Salt** is charged last, having a mixing time of 1 min, with 5 L of RO water. Mohr is a reducer agent that is a part of Redox catalyst. Reacts with TBHP to initiate the RX by assisting with the generation of free radicals. ## Polymerization Once the polymerization process is underway the aqueous monomer solution undergoes three steps: initiation, propagation, and termination. Our polymerization reactions are considered free radical reactions. Free radicals are molecules having an unpaired electron that's seeking stability. Free radicals are generated by redox reactions, thermal degradation, and chain transfer agents. - **Initiation** occurs when free radicals react with monomer molecules (Acm, Acrylic Acid, and ATN) - thus triggering polymerization. - **Propagation** takes place when a monomer molecule, that has reacted with a free radical, begins to react and form bonds with other monomer molecules, forming a polymer. - **Termination** occurs when the polymer molecule stops gaining monomer molecules. This occurs through by 3 causes: - Another free radical attacked the end of the polymer chain, not allowing a new free radical to form (disproportion). - Two chains with free radicals combine (combination). - There is an absence of unreacted monomer. After the Mohr Salt is charged to the Reactor, the O. Op Records the time and temperature of initiation by watching the control panel and waiting for temperature to increase 0.30C for induction time. As the polymerization process is underway, heat is released as the monomers react to form polymer chains. Reactions will take anywhere from thirty minutes to over three hours to run. The time it takes depends on the molecular weight of the product. The longer the reaction runs, the more time the polymer chain has to build molecular weight. The polymerization process ends after the termination phase, in which the reaction peaks of out. The peak time is the time at which the temperature of the gel stops increasing, which around A reaction will peak out at 750C - 1000C depending on the product. At this point almost all the monomer has reacted. Thereafter the gel is held in the Reactor for a residency time. This is the time needed to lower the residual monomer within spec. The hold times are usually 1, 2 or 3 hours depending on the product. ## Reactor Polymer Gel transfer (cutting) The polymer gel is extruded from the reactor, where it’s transferred by a horizontal screw to a vertical screw, then into the gel hooper. The gel hopper is used to maintain a consistent flow of product to the granulator. The product is gravity-fed to the dosing screw and is then pushed into the granulator by the screw. The granulator cuts the gel to uniform particles, which allows the product to dryer easier. The gel is sprayed with a mixture of air/oil to soften it for cutting (S-275) ## Drying The phases of the drying process on LP1 & LP2 differ slightly than Lp3&4. Therefore, I’ll proceed to explaining lines 1 and 2 drying process and then follow with Lp3 &4's drying process. ### Dryer 1 Thereafter, the granulator transfer fans transfer the gel from the granulator to the Dryer 1. Dryer 1 on Lp1 & Lp2 uses Evaporative drying which occurs from about 70% moisture down to about 25% moisture. The gel is still wet in this phase. The heat from the burners evaporates the water from the surface of the particle, therefore drying the gel outside in. The product can handle the high temps because of the water, without the water the product would crosslink at such high temps. The air and rotors work together to evenly dry the product and the product exits the dryer 1 by its outlet screw and is transferred to and transfer screw that feed the Product to Dryer 2's inlet screw. Also, Dryer has two cyclones. The cyclones separate the product and coarse dust from the air, which allows the dryer air to vent out through the ducts and stack, while returning the product to the dryer2. ### Dryer 2 Dryer 2 uses diffusional phase drying. In this phase the water is no longer on the surface but is being pulled from inside the particle. In the diffusional phase the moisture drops from 21% to 11% or below. Dyer 2 should be watched closely because the product can be easily over dried which causes the greatest chance of cross-linking and solubility problems. Like Dryer 1 the air and rotors work together to evenly dry the product, the product then exits dryer 2 by it’s outlet screw and transferred by a transfer screw into Dryer 3. Also, like Dryer 1, Dryer 2 have two cyclones which differs from LP1 cyclones, by way of transferring the Dryer air from Dryer2 back to burner1 fan and feeding the air back into dryer 1. ### Dryer 3 Dryer 3 is a cooling dryer. The purpose of this dryer is to lower the temperature of product before it’s packaged which prevents the product from remassing. Once drying is complete, the product is transferred by Dryer 3’s transfer screw into the kason. ## Kason The kason is used to separate oversized product from good product. It removes any big remassed clumps, so will not jam the roller mills. Good product passes through the screen, and oversized product is discharged out in the trashcan. The finish product that passes through the Kason’s screens is feed into a pair of pants that’ll transfer the product through lines BR1 and BR2, after the pair of pants, the reclaim product from dryer 3’s post treatment cyclone is feed through a pair of pants into BR1 & BR2, and the product is then transferred into the apex screens. ## Apex The apex separated the product that exits the dryer. It screens the product to be product/customer specs by separating the product that exits the dryers into oversized, finish product and fines. The oversized product that leaves the apex goes to the roller mill and recycled back through the cyclone and then it passes back through the apex again for rescreening. The fines exit the bottom of the apex and discharged into the fines hooper. The finish product exits the middle of the Apex, where its transferred to the speed box(cooling box), The speed box attaches to the dehumidifier. The dehumidifier removes the moisture from the air, which keeps the product dry so it want remass. The cool air from the dehumidifier cools the product as its being transferred from the speed box to the cooling cyclone. ## Cyclone - Pre blend transfer Pot The cyclone separates the product from the transport air, and the dust is sent to DCE, and finish product is transferred through the cyclones rotary valve into the Pre-blend transfer pot. Then the product is transferred from the Pre-blend transfer pot to the pre-blend silo. The product is then transferred from the Pre-blend silo to the rotary blender, if applicable the addition of any material that needs to be blended back can be blended back with the finish product. Then, the product is transferred from the blender to a post blend transfer pot. The post blend transfer pot then transfers the product to a QC silo. The product in the QC silo is then sieved through a kason, removing any trash from the finish product before it’s bagged or loading into a truck. ## LP3 Post Hydro Process The main distinction between LP1/2 oppose to LP3's post hydro process is caustic addition and the ph adjuster. When charging the D-tanks during the post hydro process caustic isn't added into the D tank, acetic acid is used instead of acrylic acid. Reason being, when caustic is charged with solutions containing Acrylic Acid the Sodium in caustic reacts with the Acrylic Acid molecules which is considered a neutralization process, thus yielding sodium acrylate a salt derivative. The product’s anionic charge comes from the Acrylic Acid. Standard and EOR products uses this powder's synthesis. Our standard and EOR products have lower to mid-level molecular weight range with UL's that range from 3 to 7.5, the Post hydro process is needed to assist products with achieving a higher molecular weight, having ul's in that 8-9.5 range. The charging of catalyst and phase of polymerization is the same as Lines 1 & 2. So I'll begin with the Grinding. ## RX to Pre grinder Once Residence time has elapsed, the reactor is pressurized and the gels is drained through the Reactors drain valve, and the gel is either dumped or transferred by a screw into the pre grinder. The pre grinder is used to tear the gel, to maintain a constant flow into GR1. ## Granulation GR1 cuts the gel to uniform particles, which allows the product to dryer easier. The gel is sprayed with a mixture of air/oil to soften it for cutting (S-275). The Gel then exits GR1 and transferred by GR1's fans into M1 & M2 blenders for caustic addition. ## M1 & M2 The gel is sprayed with caustic, a specific caustic ratio is factored for each product. After the caustic addition the gel is transferred by transfer screw into R9. R9 is reactor, where the gel is held for its residence time. The gel is held at 90 degree C for between 1-2 hrs depending on the product molecular weight. While in R9 the hydrolysis process in under way and the caustic hydrolyzes the gel, thus creating an acrylic acid tail on the polymer chain which gives the gel its anionic charge. ## R9 transfer to GR1 Once Residence time has elapsed the gel is transferred to GR2 for cutting. GR2 cuts the gel to uniform particles, which allows the product to dryer more evenly. The gel is sprayed with a mixture of air and oil/ to soften for cutting. ## GR1 to Dryer 1 Dyer 1 is considered a flash dryer, dryer 1 burns off the oil that was sprayed on the gel in Gr2. The moisture in Dryer 1 is 54% max, reason being if the moisture any higher when the gel is being transferred Dryer 1's exit screw, the gel will clog as it enters into dryer 2 due to gel being to wet. ## Dryer 2 & 3 Dryers 2 and 3 are fluidized bed dryers. They use air alone to fluff the product. The fans up top on the dryer deck blows air through the wind box and enters the dryers through bubble caps. The hot air comes in contact with the entire surface area of the gel, therefore drying the product more evenly due to the fluid motion. The product then exits dryer 2 by overflowing the gate at the end of the dryer. The height of the gate controls the level inside of the dryer. Dryer 2 utilizes evaporative drying, therefore drying the product from outside in. Dryer 2 also, have 5 cyclones which work similar to LP1/2. Dryer utilizes diffusional drying, which dries the product from the inside. Dryer 3 also has 5 cyclones. Cy1-3 returns the hot air into dryer 3 and cy 4-5 sent the air process air into line Br1 & 2After Dryer 3 the product is feed into a kason. The finish product that passes through the Kason’s screens is feed into a pair of pants that’ll transfer the product through lines BR1 and BR2, after the pair of pants, the reclaim product from dryer 3’s post treatment cyclone is feed through a pair of pants into BR1 & BR2, and the product is then transferred into the apex screens. ## Cyclones - Apex - RM - Mines - ct5 - Cooling cyclone - Hopper - Post Blend transfer pot - Pre blend silo - M3 & m4 Qc silo - Kason - Bags or trucks Ct5 to cooling cyclone, to