Process and device for slurry bed methanation using monolithic catalyst

Abstract

A slurry-bed methanation process using monolithic catalysts is to reduce the monolithic catalyst after loading the monolithic catalyst into the monolithic reactor, feed the paraffin into the monolithic reactor from the top, and switch the reducing gas to syngas The methanation reaction starts, and the generated gas phase products are discharged from the top of the monolithic reactor. Part of the gas phase products is used as circulating gas, and the other part of the gas undergoes gas-liquid separation, and the gas phase is the natural gas product. Paraffin hydrocarbons flow downward from the top of the monolithic reactor, and after the catalyst layer and the synthesis gas are in reverse contact for heat exchange, they are discharged from the bottom of the monolithic reactor for gas-liquid separation, and the gas phase and gas phase products at the top of the monolithic reactor are separated mixed, and the liquid phase paraffin returns to the monolithic reactor for recycling. The invention has the advantages of low energy consumption, easy operation and no catalyst separation.

Description

technical field [0001] The invention belongs to a coal-to-natural gas process and device, in particular to a process and device for slurry-bed methanation using an integral catalyst. Background technique [0002] my country has the energy status of rich coal, poor oil and little gas, so the comprehensive optimization and utilization of coal resources is imminent. In recent years, with the rapid increase of natural gas demand in my country, the gap between domestic natural gas supply and demand has gradually increased, which in turn has restricted the steady and rapid development of my country's national economy. Coal-to-natural gas is a technology that uses coal as raw material to produce natural gas. It can convert coal into a clean fuel CH that is convenient for long-distance transportation. 4 , is an important way to alleviate the contradiction between supply and demand of natural gas and realize efficient and clean conversion of coal. [0003] Methanation is the core t...

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Problems solved by technology

[0008] Although the monolithic catalyst shows more advantages than the traditional stirred slurry bed reactor in the heterogeneous reaction, it still has the following disadvantages due to the insufficient design of the reactor and the structural characteristics of the catalyst itself: (1) The heat transfer effect is not ideal, because the pores of the monolithic catalyst are relatively independent, and there is no mass transfer between adjacent pores, so there is no radial heat transfer, and the radial heat conduction through the pore wall is also very low, so For the exothermic reaction, the reaction temperature will rise rapidly, while for the endothermic reaction, the phenomenon of sudden stop of the reaction is more likely to occur due to the cooling of the stirred slurry bed reactor; (2) the liquid phase is in the monolithic reaction The distribution at the cross-section of the device is not uniform. Due to the limitation of the manufacturing process, the height of a single monolithic catalyst is limited. In order to achieve the required catalyst bed height, the monolithic catalyst needs to be stacked in series in multiple layers so that the liquid phase is in contact with the two monolithic catalysts. (3) The loading and replacement of the monolithic catalyst is still troublesome. Although the shape and pore structure of the monolithic catalyst are relatively regular, it is necessary to ensure the perfect docking of the pores between the layers during the catalyst loading process, and the The size of the gap between the radial catalysts should be controlled to be moderate, and at the same time, due to its relatively large loading volume, it will be more troublesome to replace the catalyst due to local catalyst deactivation

The monolithic catalyst has many advantages in the gas-liquid-solid three-phase reaction, but due to the insufficient design of the monolithic reactor, it is impossible to achieve a perfect match between the monolithic reactor and the monolithic catalyst, which leads to low heat transfer efficiency and liquid along the horizontal direction. The shortcomings of uneven cross-section distribution and troublesome loading and replacement of catalysts limit its industrial application

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