Intermediate products, such as ethylene oxide, ethylene glycol, ethylbenzene and propylene oxide are used in the petrochemical industry for the production of a range of products like polyester fiber and resins. Since these substances are flammable, reactive and toxic, special attention is required to control risks related to safety and the environment during production and product handling. The Neles Finetrol valve with live-loaded graphite packing is a reliable solution for various control purposes and it has been widely used in these plants.
Product Discharge from Reactor
In a gas-phase fluidized-bed reactor PDS-system a series of valves and piping is used for product conveyance, isolation, gas venting, recycling and cross tying. There are a number of heavy demands related to these applications. In the most demanding cases only metal-seated ball valves are suitable. Neles XG series trunnion-mounted full bore ball valves equipped with a double-acting, high-cycle, B1 series cylinder actuator have a proven performance. The B1J series actuator is tested to deliver over two million cycles. The XG series valve’s rugged polymer-proof metal seats are coated with tungsten cobalt carbide for superior wear resistance, long-lasting tightness and to prevent polymer build-up behind the seat. The ball, also coated with tungsten cobalt carbide, is furnished with an XM-19 shaft to withstand high cycling, sometimes over 800 000 cycles per year, and fast operating speeds of less than two seconds.
Neles Finetrol, Segment and Neldisc control valves have been widely used for various control applications in polymerization processes, such as reactor cycle gas, reactor feed, and gas to flare. Intelligent and reliable control performance from Neles is your answer, if you are looking for compact control solutions without polymer build-up and reduced fugitive emissions.
Cracking furnace and distillation
Ethylene is a basic building block of the chemical industry, and is the link between chemical companies and petroleum refiners. The ethylene or olefin plant will yield mostly ethylene, but will also break the feedstock into a number of usable by-products, such as propylene and butylenes. Neles Finetrol and Segment valves have been widely used in many olefin plant applications – from feedstock and steam supply to cracker furnace, fuel gas to burners and various applications in cracked gas cryogenic refrigeration systems and cold-separation distillation columns. Neles control valves provide proven reliability and accuracy to control applications with a single valve solution that eliminate the use of split range control. Q-trim technology reduces noise and cavitation, and fire-safe design assures availability in the most severe conditions.
X-MBV is an excellent example of proven reliability in cracked gas effluent sampling with its long-term tightness and scraping seat design that resists erosion and coke deposits.
Steam cracking furnaces
Steam cracking cryogenic distillation
Steam cracking flare
Steam cracking gas compression
Steam cracking quenching (ethylene)
Potential hazards associated with petrochemical industries are explosions, fires, and releases of toxic sub-stances. Petrochemical plants have large numbers of ESD and ESV valves. The Neles ValvGuard™ partial stroke testing system, is a new-generation, safety-management system that helps to ensure that the ESD and ESV valves will always perform properly when needed. With this TÜV-Certified system that meets SIL 3 requirements, you can easily monitor and test valve performance for maximum availability, while reducing overall operating costs. Neles ESD/ESV valves are the better way to assure increased risk reduction thanks to rugged metal seats for long lasting, safe and fast operation with reduced fugitive emissions.
Gas to flare system ESV & ESD valves
Compressors are used in many different locations in the ethylene plant, for example to compress the cracked gas before the fractionation stage, compress the purified gases for storage, or simply to supply plant air. To protect compressors from gas pressure oscillation that can cause severe and costly damage to the compressor in a few seconds, many anti-surge and recycle control systems have been equipped with Neles Q-Ball® valves. Experience shows that the Q-Ball noise reduction trim, in Neles rotary valves, provides full control performance even during different flow conditions. For higher pressures, the Top entry ball valve can provide ANSI 600 ratings. The robust construction achieves the pressure drop and load resistance to handle extreme conditions. For lower pressure compressors, mainly high-flow axial type, Neldisc® eccentric disc butterfly valves are an economic and effective alternative.
The propane dehydrogenation process is used to supply polymer-grade propylene from propane to meet the growing propylene market, independent of a steam cracker or FCC unit. Valves play an important role in ensuring proper propane dehydrogenation process performance.
The steam methane reforming process is used to produce hydrogen for refinery hydrotreating, hydrocracking, petrochemical and chemical manufacturing. Further ammonia and methanol are produced by synthesis reactions. Metso’s metal seated Neles, soft-seated Jamesbury and high pressure Mapag butterfly valves for control and isolation provide a complete offering of high performance, friction-free tight valves with a wide selection of materials for optimum steam reformer furnace performance and synthesis processes that ensure top-quality synthesis gases for various chemical and petrochemical purposes.
The polysilicon process begins with converting silicon (Si) into trichlorsilane in a fluid bed reactor. The distillated trichlorsilane is converted into high-purity polysilicon in a chemical vapor deposition (CVD) reactor.
During the process, raw material, intermediate products and byproducts include Si powder, Cl2, H2, HCl, SiHCl3, SiH2Cl2 and SiCl4, therefore a valve’s design must be able to deal with these mediums, especially the highly abrasive Si powder.
The chemical compounds are extremely dangerous. H2 and SiHCl3 are easily combustible. HCl is dangerous and extremely corrosive. SiCl4 will produce hydrogen chloride and SiO2 if it leaks from the packing and mixes with water. This will easily lead to corrosion and packing jamming. Consequently high efficiency emission control is required. It is necessary to recover these substances and bring them back into the production process. Safe handling of these chemicals, environmentally sound disposal as well as emission control at the same time should be considered carefully. The aim is to capture and recover all these chemicals to decrease raw material consumption and increase the whole process efficiency.
Metso is answering to these challenges with intelligent reliability:
Chlorine Hydrogen Processing
H2 exits the cell at 90˚C (194˚F) and is cooled to about 21˚C (70˚F) before distribution. The H2 temperature is cooled through a series of heat exchangers. Our manual high-performance Class 150 lugged Wafer-Sphere® valves control cooling water to the heat exchangers. Carbon steel by 316SS is the recommendation. The H2O is at 21˚C(70˚F) and 6 bar (90 psi).
Hydrogen is distributed to operations at 21˚C (70˚F) and 3 bar (45 psi). Automated Class 150 lugged Wafer-Sphere with carbon steel bodies and 316SS trim along with CINTAC actuators automatically isolate the heat exchanger and user process.
Because the H2SO4 is circulated at about 3 bar (45 psi) and 32˚C (90˚F), the Metso-recommended isolation valve is a 2” to 3” Class 150, preferably carbon steel with Alloy 20 ball and stem. Our manual 1” Class 150 of the same material is a proven choice for the acid bleed valve.
With cooling water at 21˚C (70˚F) and 4.5 bar (70 psi), 2” to 3” class 150 valves with carbon steel by 316SS ball and stem are the preferred materials. The cooling water control valve is 1 ½” to 2” Class 150 valves with Quadra-Powr® X (QPX) spring diaphragm actuator with positioner and accessories as specified.
Compressor isolation is the ideal application for a manual lugged Wafer-Sphere ® valve with carbon steel body and Monel disc and shaft. For Cl2 gas control, it is the same valve, body material, disc and shaft; but you can add a QPX spring diaphragm actuator with positioner and accessories as specified.
Cooling and chilled water temperature applications are ideal for Wafer-Sphere ® valves. Applications include chilled water return and supply, cooling water pump isolation, cooling water supply, cooling water temperature control, and chilled water control. Cooling water operating conditions are about 27˚C (80˚F) and 6 bar (90 psi). Chilled water conditions are about 27˚C (45˚F) and 6 bar (90 psi).
Modulating control valves include the Quadra-Powr ® X spring diaphragm actuator with positioner and accessories as specified.
Hot water at 42°C (140˚F) and 5 bar (75 lb) is modulated by a flow control valve to maintain vapor-producing temperatures in the liquid Cl2 chamber of the vaporizer. Cl2 feeds the process at about 32°C (90˚F) and 5.5 BAR (80 psi) through a rotary control ball valve. Process pressure regulates valve position. A fail-closed emergency shutdown valve isolates the vaporizer from the process and can be instrumented to fail on a signal from a variety of sources. Shut-off logic is process dependent.
Numerous drain and isolation valves are involved. Flanged manual valves isolate the vaporizer, hot H2O or steam control valves. Manual Cl2 valves isolate the Cl2 control valve. A thread end valve isolates the hot H2O or steam pressure gauge. A threaded Cl2 valve isolates the Cl2 gas pressure gauge. The condensate outlet and vaporizer drain lines shut off with 1” thread-end valve.
Chlorine Tank Car Loading
Today, workers are loading tank cars 20% faster than they used to, thanks to new valves from Metso. This was achieved by replacing bulky bellows-seal globe valves, used for emergency shutdown service during loading operations, with compact, automated full port ball valve packages having a substantially higher Cv rating. The Cv for the 1” Jamesbury® 9300 C, 300 lb. ball valves is 45 compared to a rating of 10 for the bellows-seal globe valves.
One Jamesbury package includes the full port ball valve (1” 9300C 31 2273 XTZ1) with CR20SR633HASRM, an advanced CINTAC® spring return automation and communication package. The CINTAC automation system takes the latest on-off monitoring or networking technology and combines it with a pneumatic module and state-of-the-art actuator. This compact integrated package requires no external fixtures, tubing or linkage and includes visual status indication. Any of the valves can be repaired quickly on-site, using an $80 repair kit supplied by Jamesbury.
Chlorine Tank Car Loading
High-performance Wafer-Sphere ® valves with handles or gear actuators are used to isolate the refrigerant holding tank and condenser. Wafer-Sphere modulation control valves control refrigerant level and pressure in the evaporator liquefier. Cooling water to condenser is about 21˚C (70˚F) and 6 bar (90 psi). Carbon by 316SS is the recommended material. High performance Class 150 lugged Wafer-Sphere valves with gear actuators are used to isolate the condenser from the cooling water system.
Compressed chlorine is cooled in liquefiers and transferred to the liquefaction knockout pot where uncondensed tail gas leaves the liquefaction process. Located in the tail gas line are high performance ANSI Class 300 lugged Wafer-Sphere valves of carbon steel with Monel® trim, maintaining compressor pressure at 3 bar (45 psi).
As liquid chlorine leaves the liquefaction knockout pot, it is modulated by a high performance ANSI Class 300 lugged Wafer-Sphere control valve that modulates the rate of Cl2 consumption. Carbon steel with Monel trim is the recommended material. If the chlorine is going to storage, a modulating valve may not be required.
Chlorine Chemical Treatment
A variety of valves are involved in the chemical treatment process and Metso manufactures every one of them. This includes various pump and tank isolation valves as well as rotary modulating control valves. It is the rotary modulating control valves that feed caustic soda or caustic potash (KOH) in precise amounts to remove heavy metals. Rotary control valves also add carbonate at precise levels to remove calcium. Because lines are small, modulating control valves can be line-size and can include Quadra-Powr® X spring diaphragm actuators with positioner and accessories as specified.
Chlorine Chemical Treatment
Chlorine Caustic Evaporation
While temperatures tend to be higher in the processing of liquor, the evaporation process does not present any challenges from a pressure prospective. Temperature does have an effect on material selection There is extensive use of modulation control and isolation valves in the evaporation process. First and second effect control valves modulate from either liquid level or temperature control from evaporators. Caustic discharge control is modulated by caustic density or temperature. First effect heat exchanger temperature is controlled by modulating 6 bar (100 psi) steam flow. There are also numerous manual isolation valves on pumps and evaporation tanks and heat exchangers.
Chlorine Caustic Evaporation