Mineral Deposit Formation in Gas Engines During Combustion of Biogas from Landfills and Municipal WWTP

Abstract

The biogas produced in municipal wastewater-treatment plants (WWTP) should be cleaned before it can be used as a fuel in internal combustion engines. Efficient running of such engines is possible only subject to using high quality biogas and lubricating oil. Otherwise, biogas impurities in course of complex chemical reactions may form deposits on various engine parts as well as seriously contaminate the lubricating oil. In this paper, mineral deposits containing high concentration of bismuth, silicon, sulphur, calcium and zinc are studied. Silicon deposits demonstrating strong friction properties are formed during combustion of volatile silica compounds. As these deposits build up, abrasion problems, ignition failure and even engine failure result. The bismuth containing deposits comes from bearings degradation, zinc and calcium were derived from the additives present in commercially available lubricating oil, while lead, aluminium, copper, nickel, iron and chromium were introduced by engine wear phenomena. The highest bismuth content was located at the engine cylinder heads and the lowest at the exhaust elements, whereas highest calcium content was registered on the pistons. Silicon containing deposits are highest in the exhaust and lowest at the engine head. Zinc deposits are highest at the piston.

Biogas Pollution and Mineral Deposits Formed on the Elements of Landfill Gas Engines

“…The occurrence of the above-mentioned elements, as well as magnesium, tin, phosphorus and chromium, depends on the location of the gas collection site and the type of engine. Moreover, similar variations were observed in deposits from gas engines powered by biogas from a waste water treatment plant [ 25 ].…”

“…These compounds are most often found in personal care consumer products (shampoos and cosmetics), antifoaming agents, detergents and polymeric silicone products (as precursors) [ 1 , 20 , 22 , 23 , 24 ]. Moreover, the polydimethylsiloxane polymers used in a wide range of industrial and domestic applications are dispersed in various environmental facilities [ 25 ]. Thus, the problem of biogas contamination with siloxanes is observed both in landfill biogas and biogas from sewage treatment plants.…”

“…The organosilicon compounds in landfill biogas include D3 (hexamethylcyclotrisiloxane), D4 (octamethylcyclotetrasiloxane) and D5 (decamethylcyclopentasiloxane) [ 38 ]. The selected properties of commonly occurring organosilicon compounds in biogas were presented in our previous work [ 25 ]. As a result of the combustion process in the engine compartment, silicon dioxide (SiO 2(s) ) is formed [ 30 , 39 ]: …”

Characterization of Deposits Formed in Gas Engines Fuelled by Coal Mine Methane

“…Deposits collected from various parts of the engine powered by biogas from a waste-water treatment plant were characterized by a similar composition. XRD analysis confirmed oxide forms such as SiO 2 , Bi 2 O 3 , CaO, P 2 O 5 , and ZnO [ 32 ]. However, the highest contents found were silicon, calcium, phosphorus, sulphur, and zinc [ 32 ], which were also confirmed by Stanuch et al [ 25 ].…”

“…XRD analysis confirmed oxide forms such as SiO 2 , Bi 2 O 3 , CaO, P 2 O 5 , and ZnO [ 32 ]. However, the highest contents found were silicon, calcium, phosphorus, sulphur, and zinc [ 32 ], which were also confirmed by Stanuch et al [ 25 ].…”