The development of a novel continuously working lock-free feeding system for brown coal into pressurized gasification reactors requires the sealing of the gasification reactor against the feeding system. Due to the continuous operation mode and absence of locks there is a direct connection between the feeding system and the gasification reactor chamber. The required gas tightness of the transport channel can be achieved using a technical solution, which creates a plug with sufficient density and cross-bracing by compression of the brown coal. By systematic comparison of technical solutions, which are suitable to act as a feeding system for pressurized reactors the choice fell on the briquetting press. The briquetting press combines a high throughput with a high operating pressure, producing a cross braced briquette plug in the press channel, wherein the individual briquettes have high structural strength and density. An optimal constellation of briquetting parameters allows a significant increase of the briquette structure tightness. A further option to increase the tightness of the press channel and briquette structure is the use of additives. Various additives for improving the tightness of the briquette structure were tested successfully. The analysis with various additives to increase both the tightness of the briquette structure itself and sealing the press channel taken as a whole are described in more detail in this article. (C) 2013 Elsevier Ltd. All rights reserved.