Chemicals & Materials

Trip & Throttle Valve Reliability Trip & Throttle (or Stop) valves are used in ethylene plants to isolate the energy to steam turbines when required. They are critical Safety Protection components with a high impact on a plant’s reliability; however, they operate under tough conditions like...

Many of the practical problems in achieving high performance feedback control for challenging applications have been addressed by modifications to the basic PID control law. These modifications include set-point filters that allow both load rejection and set-point following objectives to be...

Braskem, a Brazilian player among petrochemical manufacturers, produces monomers, resins and chemicals specialties. The overall Ethylene capacity is 3,600 KTA, distributed in six Olefins plants. Naphtha is the main raw material of the petrochemical and plastic productive chain in Brazil, followed...

Refinery crude units often process variety of feedstocks. If properties of the feed entering the crude unit are not precisely known, it is difficult to predict how changes in the tower operating conditions will affect properties of the products. Similarly, if on-line analyzers are not available, it...

In May 2010 the Ethylene Producers Committee NOx Safety Sub-Committee sponsored a discussion on practices to mitigate NOx risk in the cryogenic section of ethylene plants. The meeting was attended by representatives of 10 ethylene producers, 4 ethylene contractors and other contractors, 2 additive...

Underlying feedstock prices that derive from either natural gas or crude oil represent a high percentage of the operating expense related to the production of ethylene for a vast majority of the global ethylene market. Historically, while steam crackers in West Europe and Asia are mainly naphtha-...

Hydrogen is even more important to refiners than it was just a few years ago. Heavier crudes, clean fuels, and increased conversion have increased hydrogen demand. Refiners can face costly choices if forced to adjust refinery operations to respond to hydrogen availability constraints. It is...

It is becoming a widespread norm that refineries are processing an increasing quantity of heavy and sour crudes than ever before. The depleting oil reserves of light sweet crudes have resulted in the need for deeper exploration. Considerable finds in the Orinoco belt of Venezuela, California and...

Chemical reaction fouling is principally controlled by two factors: wall temperature and local fluid shear stress. Computer programs for the design of shell-and-tube exchangers generally calculate a mean heat transfer coefficient for the tube bundle. In reality both heat transfer coefficient and...

Shell-tube type heat exchangers are often used to exchange heat between a high pressure fluid and a low pressure fluid, and the pressure difference between the two fluids could be significantly high. In the event of a partial- or full-rupture of a tube, a problem may arise in that a transient...