Method and device for producing methane-enriched gas from carbon-containing raw materials

Abstract

The invention belongs to the technical field of energy and chemical industry and discloses a method and a device for preparing methane-enriched gas from carbon-containing raw materials. By the circulation of solid particles used as both heat carriers and catalysts, the decoupling-optimizing control reintegration of the gasification of the carbon-containing raw materials and the methanation process of gasification products are achieved so as to obtain the methane-enriched gas, the direct conversion of solid carbon-containing raw materials to the methane-enriched gas is achieved and the device cost and the operating cost are decreased. By the heat-carrying functions of the solid heat carriers and the catalysts, the high conversion rate of the methanation process in a single-section adiabatic reactor is achieved, the circulation of a large number of product gas and multi-section methanation adopted in the conventional fixed-bed methanation process are avoided and the production cost is decreased. The catalysts has the characteristics of in-situ regeneration, convenience in renewal and the like, and thus the requirements of the process on such performances as sulfur tolerance, carbon deposition resistance and service life are greatly reduced.

Description

technical field [0001] The invention belongs to the technical field of energy and chemical industry, and relates to a method and a device for preparing methane-enriched gas from carbon-containing raw materials by using a circulating solid heat carrier catalyst. Background technique [0002] The coal-to-synthetic natural gas process is divided into indirect methanation and direct methanation. The coal indirect methanation process includes two processes of coal gasification to syngas and syngas to methane. Combining traditional coal gasification technology with fixed bed methanation technology is the mainstream technology of coal to synthetic natural gas. The process is complicated and the investment in equipment is large; The direct methanation process is to convert coal directly into methane-rich gas under certain temperature and pressure conditions, without the need for two independent operations of coal gasification and methanation. Its representative technology is based o...

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Problems solved by technology

The disadvantages of the multi-stage series fixed-bed reactor structure are: the overall equipment and process are relatively complex, the control of process parameters is difficult, a large number of product gas cycles reduce production capacity and increase power consumption, and the production capacity of single-stage reactors is limited. , fixed bed operation is likely to cause gas drift and local hot spots

In addition, due to the complex operations such as catalyst loading and activation, long cycle and high cost, the disadvantages of fixed bed reactors also include strict requirements on catalysts, that is, long catalyst life is required. Among the existing industrial methanation catalysts, the supported nickel catalyst It is widely used because of its high efficiency and relatively low cost. However, carbon deposition on the surface and sulfur species in the atmosphere can easily lead to a decrease in the activity of the supported nickel catalyst. compounds, so that the content is less than 1ppm, which will greatly increase the cost of the process

[0004] Chinese patent CN102465047A integrates coal-to-synthesis gas, coal catalytic methanation and syngas methanation into one reactor in series to achieve full utilization of energy, but this process requires pre-oxidation and ion exchange loading of raw coal Catalyst, catalyst recovery is difficult, raw material pretreatment cost is high

Chinese patent CN103450960A and Chinese patent CN103865600A each report a four-stage fixed-bed coal-to-natural gas methanation process and its system. Due to the inherent defects of the fixed-bed methanation technology, the related processes all show long process control and high technical difficulty. feature

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