What a chemical plant does

A chemical plant takes basic feedstocks and turns them into materials used far beyond Baytown. The pipes eventually become plastics, foams, insulation and everyday goods.

The refinery makes what you put in the truck. The chemical plants make what the truck is made of — and the seat, the bumper, the milk jug, the bread bag, the foam in the mattress, the insulation in the wall. Baytown has three of the biggest. Here's what they do, from the companies' own sheets and the government's manuals, in plain words.

Start with a hot pipe

The molecule at the bottom of nearly all of it is ethylene, two carbons and four hydrogens, and it's made by violence. A feed — ethane or propane from the gas fields, or naphtha from the refinery — is mixed with steam and shot through a furnace tube at 1,500 to 1,600 degrees for less than a second. The big molecules shatter into small ones. OSHA's manual gives the temperature; the industry calls the furnace a steam cracker, and the plant that holds a row of them is an olefins plant. Out the other end come ethylene, propylene and butadiene — the "olefins," the building blocks — separated by cold and pressure into pure streams. ExxonMobil's Baytown olefins plant makes about ten billion pounds of them a year, by the company's own count.

Then link the beads

An olefin is a bead with a hook on it. A polymer is a necklace: thousands of beads hooked in a chain. Feed ethylene to a reactor with the right catalyst and you get polyethylene; feed it propylene and you get polypropylene. Those two are the most-made plastics on earth, and the difference between a grocery bag, a milk jug and a water pipe is mostly how the chains are packed — low-density, high-density, linear-low — which is why Chevron Phillips's plant on Cedar Bayou lists all three grades on its sheet, along with the 1-hexene it makes to tune them. Polypropylene is the yogurt cup, the car's dashboard, the fibers in the carpet. Polyethylene is nearly everything else that bends.

The other chemistries in town

• Butyl rubber. Isobutylene, one of the four-carbon gases, linked with a little isoprene, makes a rubber that almost nothing can pass through — which is why it lines every tire on the road and seals every medicine bottle. ExxonMobil's Baytown chemical plant has made butyl polymers since the war; the Handbook of Texas records that the plant made butyl rubber and butadiene for synthetic tires when the country's natural-rubber supply was cut off.
• Aromatics. Benzene, paraxylene and their cousins — ring-shaped molecules from the reformer — that become polyester, nylon, the clear plastic in a water bottle. The same fact sheet lists an aromatics unit at Baytown. Benzene is also the reason for one of the strictest rules on the site.
• Polyurethane's raw materials. Covestro's plant, the one older Baytown still calls Bayer, makes the isocyanates — MDI is the one the company has just spent more than a billion euros expanding here — that react with polyols to make foam. Rigid foam is the insulation in your refrigerator and your attic; flexible foam is the couch, the mattress, the car seat; the coatings and adhesives are the rest. The American Chemistry Council's explainer is the plain source.
• Alpha olefins and synthetic base oils. Chevron Phillips makes normal alpha olefins and polyalphaolefins on Cedar Bayou; ExxonMobil lists a linear alpha-olefins unit and synthetic motor-oil bases. The full-synthetic oil in a new truck starts as a gas on this side of the Ship Channel.

Where it goes

Most of it leaves as pellets — small white beads in railcars and bags, headed to the molders and film plants that turn them into things. That's why the industrial park east of town runs on rail, why the plastics-handling firms sit next to the distribution centers, and why a Baytown kitchen in the morning is a catalogue of the chemistry a few miles away: the jug, the bag, the cooler, the shoes, the phone in your hand. Nobody thinks about it. That's the point of it working.

A town that makes the world's plastic is a fair place to try unmaking it.

The difference between the two kinds of plant

A refinery's product has to burn. A chemical plant's product has to last. That single difference decides almost everything else — the chemistry, the equipment, the hazards, and the jobs. A refinery runs on distillation and cracking; a chemical plant runs on reactors and catalysts and very cold separation. Both run around the clock, both turn around every few years, both hire operators from the same program at Lee College — and both are, to the operator on shift, a set of numbers on a screen that must stay inside their lines.

The pellet

Every plant worker in Baytown has found one in a pocket, a truck floorboard, a boot tread: a white or clear bead the size of a lentil. That's the product. Not a barrel, not a flame — a pellet, by the billion, poured into hopper cars and bags. A pellet spilled on the ground is called a nurdle, and keeping them out of the bayou is a real job with real rules; a pellet in a child's hand is the whole industry made small enough to explain. Hold one and you're holding what the towers were for. It's the least dramatic object in town and the one that ends up in the most homes.

How to tell the plants apart from the road

Driving Highway 146 or Decker or the Spur, the fences run together. They don't have to. The refinery is the one with the most towers and the biggest flare, on the Ship Channel side, and it's been there since 1919. The olefins and chemical units share its fence; the long rows of furnaces with many short stacks close together are the crackers. Cedar Bayou is the one on the east side with the wide green buffer before the units start — the company keeps more than half its land as open ground, and you see it as prairie before you see steel. The isocyanate plant is the one older residents still call Bayer, and it has more rail than most: the product leaves in tank cars, not pipelines. Up 146, the spheres and the salt-dome tank fields with almost no towers at all are Mont Belvieu — storage and fractionation, not refining. Ten minutes of looking and the fences have names.

What comes back

The newest unit on the big site is one that runs backward. The company started up one of North America's largest advanced-recycling facilities at Baytown, which takes used plastic that can't be recycled the ordinary way and breaks it back down toward the molecules it came from, to be made into new material. It's small against the whole, and it's real, and it's on the company's own news pages with a date. A town that makes the world's plastic is a fair place to try unmaking it. Whether that grows is a business question; that it exists here first is a Baytown fact.

Why it matters that you know

Because "the plants" is what the town says, and the plants are not one thing. The refinery, the olefins plant, the polymer units, the isocyanate plant on the east side, the fractionators up in Mont Belvieu that feed them all — each is a different chemistry with a different day. When the flare goes at Cedar Bayou it isn't the refinery. When the badge says "process tech" it means all of them. Knowing which is which is the beginning of being from here.

Read it plainly

• Feedstock goes in.
• Chemistry changes its structure.
• Separation follows reaction.
• Quality checks follow separation.
• Storage comes before shipment.
• Different units make different molecules.
• The final product may be invisible here.

Sources

OSHA Technical Manual, Section IV, Chapter 2 (steam cracking temperatures, polymerization). ExxonMobil Baytown Complex fact sheet (olefins volume, chemical-plant units). Chevron Phillips Chemical, Baytown location page and Cedar Bayou fact sheet (products). Covestro, MDI investment announcement and Baytown site pages. American Chemistry Council, "Diisocyanates Explained." Texas State Historical Association, Handbook of Texas, "Exxon Company, U.S.A." (wartime butyl and butadiene production). Britannica, polyethylene.

En español

Lo que hace una planta química: la refinería hace lo que se pone en la camioneta; las plantas químicas hacen de lo que está hecha la camioneta — y el asiento, la defensa, el galón de leche, la bolsa del pan, la espuma del colchón, el aislante de la pared. La molécula base es el etileno, hecho en un horno de craqueo con vapor a 1,500–1,600 grados en menos de un segundo, según el manual de OSHA; la planta de olefinas de ExxonMobil en Baytown produce unas diez mil millones de libras al año de etileno, propileno y butadieno, según la empresa. Luego se enlazan las cuentas: el etileno se vuelve polietileno (bolsa, galón, tubería, según cómo se empaquen las cadenas — baja, alta y lineal baja densidad, las tres en la planta de Chevron Phillips en Cedar Bayou) y el propileno se vuelve polipropileno (el vaso de yogur, el tablero del auto, la alfombra). Otras químicas del pueblo: el hule butilo (forra cada llanta y sella cada frasco de medicina; Baytown lo fabricó para las llantas sintéticas de la guerra, según el Handbook of Texas); los aromáticos (benceno, paraxileno → poliéster, nailon, la botella de agua); las materias primas del poliuretano en Covestro — el MDI que la empresa acaba de ampliar con más de mil millones de euros — que se vuelven espuma rígida (el refrigerador, el ático) y flexible (el sofá, el colchón, el asiento); las alfa olefinas y las bases de aceite sintético. Casi todo sale en pellets por tren hacia las plantas que lo moldean. La diferencia: el producto de una refinería tiene que arder; el de una planta química tiene que durar. Ambas trabajan las veinticuatro horas, ambas hacen turnarounds, ambas contratan operadores del mismo programa de Lee College.

El pellet. Todo trabajador de planta ha encontrado uno en un bolsillo o en el piso de la camioneta: una cuenta blanca o transparente del tamaño de una lenteja; ese es el producto, por miles de millones, en tolvas y sacos; un pellet en la mano de un niño es toda la industria hecha pequeña. Cómo distinguir las plantas desde la carretera. La refinería es la de más torres y la antorcha más grande, del lado del Canal, desde 1919; las unidades de olefinas y químicos comparten su cerca — las filas de hornos con muchas chimeneas cortas son los craqueadores; Cedar Bayou es la del lado este con la franja verde ancha antes del acero; la planta de isocianatos es la que los mayores llaman Bayer, con más vías de tren que casi ninguna; las esferas y los campos de tanques sin torres, subiendo por la 146, son Mont Belvieu — almacenamiento y fraccionación, no refinación. Lo que regresa. La unidad más nueva del sitio grande corre al revés: una de las instalaciones de reciclaje avanzado más grandes de Norteamérica, que descompone plástico usado hacia las moléculas de donde vino; pequeña frente al conjunto, real, y en las páginas de noticias de la empresa con fecha.