Using Worked-out Tires for Methanol Production
Scientists of Ural Federal University suggested using old automobile tires for methanol production. It's supposed to be done using the method of steam gasification of tires at the temperature of 700 °C to obtain synthesis gas and then converting it into methanol.
According to Sergey Shcheklein, head of the UrFU's Academic department of Nuclear Power Plants and Alternative Energy, the heat energy required for the process is obtained from combustion of 0.368 of the synthesis gas produced, while the steam required for the gasification is produced in the waste heat boiler. The synthesis gas is purged of hydrogen sulphide and excessive carbon dioxide with monoethanolamine. The methanol is obtained in the circular reactor at the pressure of 3 MPa and the temperature of 270 °C in the presence of copper-bearing catalyst.
'The steam gasification of automobile tires is done in a spinning cylindrical reactor with a device for loading in the tires and ejecting the metal cord and dry carbon residue,' says Sergey Shcheklein. 'The amount of rubber recycled by the installation reaches 457 kilograms per hour, while producing up to 328 kg per hour of methanol. Our calculations made under the guidance of Prof. Aleksey Dubinin and Associate Prof. Andrey Matveyev, showed the effectiveness and practicality of the technology.'
The installation consists of a device for airproof loading of tires with a lock chamber, a cold-boxed on-frame reactor combined with a combustion space, units for airproof ejection of dry carbon residue and metal cord, a waste heat boiler for steam production, a block for hydrogen sulphide and excessive carbon dioxide removal, a synthesis gas compressor, and a flow-through unit for producing methanol from CO and H2 on a copper-bearing catalyst at the pressure of 3 MPa and temperature of 270 °С. For removal of combustion products there is a smoke exhauster and a smoke stack.
'The reactor is made of high tensile steel,' comments Sergey Shcheklein. 'The temperature inside is around 700 °С. Continuous operation allows us to dispose tires without complete cooling of the reactor thanks to the device for continuous loading of tires through the lock chamber and devices for airproof ejection of processed products. There is also a press for briquetting tires before loading into the reactor. The inner shell of the reactor's cylinder is equipped with a spiral, while the end wall has blades for unloading the dry carbon residue.'
The physico-chemical model of technology for obtaining methanol from waste tires opens up the possibility of converting difficult-to-process waste into raw materials for organic synthesis enterprises. The resulting methanol can be used for production of formaldehyde used in production of polymeric materials.
Such materials, in turn, are necessary for producing urea-formaldehyde and phenol-formaldehyde, urea, melamine and other synthetic resins, and recently a new plastic material, polyformaldehyde, which is characterized by high mechanical strength, chemical stability and ease of processing. Methanol can also be used as fuel for motor vehicles and aviation.
Studies have shown that at a gasification temperature of 700 ° C, the synthesis gas output is 0.37 m3 per second with a tire consumption of 0.127 kg per second, the combustion heat of synthesis gas is 9,385 kJ / m3, the thermal efficiency of the installation is 55%, and the yield of methanol is 0,091 kg / s. The specific consumption of tires for methanol production is 1.39 kg of tires per 1 kg of methanol. The share of synthesis gas used to heat the cylindric reactor is under 0.368. The most important advantage of the technology is the possibility of disposing waste while obtaining valuable chemical raw materials with minimal additional load on the biosphere. The results show the effectiveness of the technology and the possibility of its practical application.
The scientific group of this project under the leadership of Sergey Shcheklein will become a part of the world-class interregional research and educational center, which is now being created in the Urals under the national project "Science".
Recycling and efficient use of waste is one of the urgent challenges the humanity is facing at the current stage of development. Used car tires pose a significant threat to the environment, so their efficient recycling is very important. The global volume of this type of waste is estimated at more than 10 million tons per year, in Russia 1 million tons per year.
The use of worked-out tires is of great economic importance, since the elimination of the landfills will make it possible to free up significant areas of land and use them for their intended purpose. Recycling waste tires into other useful products is also of significant economic importance. Currently, a number of technologies for tire processing are used: mechanical, cryogenic technology-based, chemical methods, ozone processing, tire pyrolysis and gasification. With all the variety of existing technologies, the problem of used tires disposal is still present.
Provided by Ural Federal University