Results of investigation in corrosion processes in gasifyer gasifying fuels containing straw and lignin

Abstract

To gasify low quality biofuels it is proposed to use a downdraft gasifier with productivity by gas 60-68 m 3 •h-1. The research was made for fuel mixtures of chopped straw and hydrolyzed lignin with variable acidity. A multifactor experiment was made to estimate the influence of acidity and the moisture content of fuel mixture as well as temperature in an active zone of the gasification chamber on corrosion rate of an experimental specimen made of 15Cr21N5T. Similar experiments were made for specimens made of S32109, A57036 and Ni70Cr27Al. It was found that the moisture content influences corrosion more than acidity. Minimal corrosion rate was observed for fuel mixture with the moisture content 25 % and pH6. When raising temperature in the gasification chamber active zone from 600 to 1000 ºС, the corrosion rate rises by 8 % for the mixture with the moisture content 25 % and pH6 and by 17 % for the mixture with the moisture content 45 % and pH5. Within the interval 900-1000 ºС the highest quality producer gas was received having the calorific value of 9.6 MJ•Nm-3 with output of 2.7 m 3 •kg-1. It is confirmed that between 900-1000 ºС chloride and sulphide corrosion is significant for all types of materials. Raising the nickel content in alloy is lowering its corrosion resistance, which is confirmed with the specimen made of Ni70Cr27Al. Adding superheated steam to blowing gases is intensifying all corrosion processes. The received results of the corrosion processes could form a base of studying and computing other types of thermo-chemical conversion of low quality biofuels with similar chemical composition.

Bulk density of chopped wheat straw - influence of moisture content, fine fraction content and coefficient of compaction

“…However, with direct burning plant raw material, particularly straw, in boilers, as well as gasifying it students meet some negative factors. Among them are: ash-slag agglomerates formation [8; 12; 16], corrosive wear of equipment [4], periodical pattern of receiving heat (gas) and presence of mechanical and chemical incompleteness of combustion without propper raw material pretreament [3; 5; 17]. Students and teachers are looking for the ways of solving these problems together.…”