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Development of heat recovery and combustion equipment for optimal replacement the natural gas by low-calorific gases

Natural gas substitution for alternative fuels. Selection the substituting gases. Fuel saving by profound waste heat recovery due to preheating both combustion air and lcv gases. Development of advanced concept and designs of high temperature recuperators of increased 2-5 times service life

In frame of the present Project, solution of the problem of natural gas saving and lowering the environmental pollution is considered from the standpoint of replacement the natural gas by alternative fuels including low-calorific LCV gases. The problem of substitution the hydrocarbon fuel (natural gas) for alternative gases makes complex multi-factor task demanding account of scientific fundamentals and development of special combustion and heat recovery equipment. The project consists of development the advanced equipment suitable to provide alternative fuels production and utilization particularly for high-temperature plants (HTP, furnaces). Gas fuels used for heating the furnace chambers accordingly Project program makes process metallurgy gases (blast-furnace, converter and other LCV-gases as well as coke-oven gas) and the gasification products of coal and solid biomass. The proper assemblies include combustion, gasification and heat recovery facilities. Using of LCV-gases is accompanied with decrease of combustion temperature and lowering the furnace efficiency. Heat recovery processes are realized mainly by preheating the combustion air, being insufficiently effective when LCV-gases are used. The single way to involve LCV-gases into the high-temperature process and to use alternative fuel in HTP makes preliminary preheating of fuel gas by using heat recovery equipment. Thus in case of using the alternative fuels in HTP we need recovery facilities – recuperative heat exchangers – to preheat both combustion components: air-oxidant and fuel gas. With such approach effective recuperator designs are required being arranged within both (air and gas) pathways. By burning the process gases being presented by corrosive, sulfur containing medium like coke-oven gas as a single fuel or in mixture with the blast furnace gas, the thermal stability of air recuperator is decreased for many times in comparison with the case of natural gas combustion. The purpose of the offered technology makes development of new concept, designs and calculation methods (mathematical models and computer codes) of advanced high temperature steel recuperators particularly of prolonged multi-times service life in conditions of attack of corrosive media. It is supposed to develop the universal recuperator design available both for oxidant and fuel as the important stage of implementation the created scientific and engineering fundamentals of substitution the hydrocarbons (natural gas) for alternative fuels (see p.2.2.1). Opportunities of enhancement the fuel mixtures potential (combustion temperature) have been arisen and would be under consideration by means of preheating both combustion air and gas fuel flows to provide the necessary operation temperature under using the process gas or synthesis gas or their mixtures with natural gas. General idea of improvement the recuperator design makes fitting the tube channels with the inserts serving as the secondary emitters and thus enhancing the internal heat exchange between the flows (combustion air, LCV-gases) and the tube walls. Two remarkable consequences are attained as a result of arrangement the inserts inside the tubes: reduction of tube walls temperature Tw in combination with increased air (or/and fuel gas) preheating temperature Ta (Tf). These advantages are caused by implication of radiative component into the limiting stage of heat transfer from flue gases moving outside the tubes, to combustion components (air, fuel gas) - within the tube channels. The following statements are supposed to testify in frame of the Project: • idea on using LCV – gases instead of natural gas due to preheating fuel gases along with traditional using of hot combustion air by means of using the high - efficient heat recovery facilities – recuperators - under industrial, municipal and domestic application; • main concept, the scientific and industrial fundamentals of improvement the recuperator design suitable both for fuel gas and for combustion air preheating; • optimization the recuperator design from the standpoint of complex thermal and hydraulic criteria. 30% fuel saving (both natural or alternative gases) as well as 2-5 times prolongation of the recuperators’ service life (in case of using the substituting corrosive gas) are seemed to present the absolutely realistic values due to the Project fulfillment.
Acronym: 
ReplaceNG
Project ID: 
5 840
Start date: 
01-01-2011
Project Duration: 
48months
Project costs: 
620 000.00€
Technological Area: 
Process optimisation, waste heat utilisation
Market Area: 
Energy Conservation Related

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