Use of pure carbon dioxide as an inerting and flow medium in powder injection systems for use in pulverized coal gasification under pressure

Abstract

A particulate feed arrangement used in pulverized coal gasification under pressure is provided. The arrangement includes a reservoir for stocking the pulverized coal, a plurality of powder injection tubes, and a metering unit. Pure carbon dioxide is fed to the components that are at operating pressure, namely the power injection tube and the metering unit, as the inerting and flow medium or fluidizing medium. The carbon dioxide-carrying components are heated in such a manner that the temperature is above the threshold of the diphase range. A method is also provided. The method allows elimination of any nitrogen in the product gas, which nitrogen is caused by the powder injection system, especially when used in pulverized coal gasification under pressure to produce a synthesis gas for the production of different hydrocarbons.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is the US National Stage of International Application No. PCT / EP2008 / 054706, filed Apr. 18, 2008 and claims the benefit thereof. The International Application claims the benefits of German application No. 10 2007 020 333.2 DE filed Apr. 30, 2007, both of the applications are incorporated by reference herein in their entirety.FIELD OF INVENTION[0002]The subject matter of the application relates to a method and an arrangement for operating a particulate feed system for the pressurized gasification of pulverized coal, having the features set forth in the claims.BACKGROUND OF INVENTION[0003]Nitrogen from the air separation unit is normally used as the inerting and conveying medium in pneumatically operated particulate feed systems for high-pressure gasification plants using pulverized coal. This process variant has proved its worth both in particulate feed systems for injecting pulverized coal into blast furnaces and also for...

AI Technical Summary

Benefits of technology

[0004]The object to be achieved by the subject matter of the application is to further develop a method and an arrangement of a particulate feed system for the pressurized gasification of pulverized coal such that the nitrogen introduced into the downstream gasification system and the attendant disadvantages thereof are avoided.

[0006]According to the invention, carbon dioxide CO2 is fed to the feed lock hopper as an inerting and conveying medium and to the metering vessel as a fluidizing medium. The sections of the plant that are operated with essentially pure carbon dioxide are heated to the point that a temperature above the threshold of the two-phase region is obtained. The invention advantageously makes use of the fact that not all the components need to be operated with carbon dioxide; instead heated nitrogen is fed to the storage bin as an inerting and disaggregating medium—with reduced cost / complexity compared to carbon dioxide.

Problems solved by technology

Although the particulate feed systems based on dense-phase pneumatic conveying operate with very high loading ratios, the nitrogen introduced into the gasification systems in many cases exceeds the permissible limits.

This is also caused by increasing process pressure in the majority of applications.

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