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In MTO reactors are critical measurement points. At the Changzhou site more than 40 Maxum II gas chromatographs monitor the complex processes and quickly detect traces of hydrocarbons

Chemical industry

The method of choice

In China, a new way of producing ethylene and propylene is through the large-scale conversion of methanol. Gas chromatography technology from Siemens, installed in specially constructed methanol-to-olefin (MTO) plants, is often selected as the method of choice.

The olefins ethylene and propylene are two of the most widely produced chemicals in the world and serve as input compounds in a number of polymers and emulsifiers. Crude oil was often used as a raw material in their production; however, in recent years, unstable oil prices along with the growing use of natural gas and coal as raw material sources have driven production from methanol, especially in China. 

In order to achieve optimal process yields in MTO plants, the use of gas chromatography is required to monitor trace amounts of components in process fluid including CO, CO2, H2, and various hydrocarbons at various measuring points. Selecting the proper gas chromatographs for this purpose and corresponding treatment processes requires considerable application knowledge and expertise. The team in the Siemens Process Industries and Drives/Process Analytics Division in China, headed by Liu Xiao, has been a valued partner of the MTO industry for many years. With more than ten major projects under their belts, the team, together with proven gas chromatography technology from Siemens, has emerged as a leader in the Chinese MTO sector.

Overcoming challenges

The Siemens Process Analytics team’s current MTO project is a combined production complex being erected in the eastern Chinese province of Jiangsu. Construction of the complex began in November 2012 and today the operator, Fund Energy Investment Holding, is about to start up the project. 

In addition to an MTO plant with a maximum annual capacity of 330 kilotons per annum, the complex consists of an olefin conversion unit (90,000 tons/year) and a plant for the production of polypropylene (300,000 tons/year). More than 40 Maxum II gas chromatographs and seven sets of analyzer houses are used to monitor the complex processes and rapidly detect any concentrations of hydrocarbons. 

Qian Zang, the Siemens sales representative for chemical and petrochemical analytic projects in eastern China, knows the challenges his customers face, as well as the benefits they gain from using Siemens process gas chromatographs. “There are many critical components in MTO reactors which need to be monitored. Our customers appreciate the variety of applications which Maxum II offers them. Complex analytic tasks can be split into simpler parallel measurements in one device – without wasting time. In Changzhou, for instance, flame ionization (FID) and thermal conductivity (TCD) detectors are combined. These detectors dispense with valves thanks to live column switching via electronic pressure controllers. Our customers can thus achieve better long-term stability and more reliability.”

Lower costs and greater flexibility 

At the Changzhou site, four Maxum II chromatograph units are equipped with modular ovens. They analyze components such as ethylene, methane, and hydrogen, and provide long-term stability at low installation and operating costs while minimizing maintenance. The flexibility of the Maxum II equipment convinced the end customer as well as the EPC, in this case the Sinopec Guangzhou Engineering Co., to proceed with installation. A combination of wide-ranging functional modules and oven variants makes it possible for a single device to cover a wide analytic spectrum. At the same time, replacement and warehousing costs are kept to a minimum, as is the need for training. 

These technical benefits, together with decades of process know-how, and analytical knowledge, have enabled the Siemens process analytics team to once again make a positive impact and highlight the excellent reputation of Siemens process analytics in the Chinese market with another successful MTO megaproject.

Picture credits: depositphotos