Cement, Energy and Environment

• b) Fisher-Tropsch synthesis: Through the Fischer– Trospch conversion process undertaken in unique low– temperature Fischer– Tropsch (l TFT) slurry phase reactors, synthesis gas is converted into heavy hydrocarbons in the presence of a catalyst. c) Product upgrading: The products created through Fischer-Tropsch synthesis can be upgraded using conventional , product- specific petrochemical upgrading processes, depending on the final slate of products required by the CTL plant operators. These processes include hydro– cracking and chemical work– up, as well as refining TECHNICAL DEVELOPMENTS IN RECYCLING HOUSEHOLD WASTE INCINERATOR ASH IN THE CEMENT INDUSTRY– CASE STUDY OF JAPAN Tomomichi Nakamura, Shin-ichiro Saito and Yasuhiro Sagara, Taiheiyo Cement Corporation, Japan. Abstract Taiheiyo Cement Corporation has been recycling household waste incineration ash as raw material for more than 10 years. This model was implemented as part of the "Zero Emission framework in Saitama Prefecture" in Japan 13 years ago when "district management of wastes" became the basic philosophy, replacing the practice of sending waste to landfill outside the region. To embody this model, Taiheiyo Cement Corporation had to through a conventional petroleum refinery. Sasol offers two technologies based on Fischer Tropsch, i.e., the high temperature Fischer Tropsch (HTFT) process (a process that produces mainly chemicals and gasoline) and the low temperature Fischer Tropsch (l TFT) process. LTFT process is ideal for producing diesel from coal (through CTL conversion) and is the best options for a plant with a simple footprint. HTFT process, however, can be used to produce a slate of white products, as well as the building blocks for high-value chemicals. The LTFT CTL three step process integrates several proven processes starting with coal gasification and is followed by low-temperature Fischer- TECHNOLOGY TREND solve two issues: optimization of the preprocessing facilities for bottom ash, and development of a desalination process for the fly ash. This article describes these developments and the operational experience gained. Introduction The Japanese cement industry's utilization of waste materials and byproducts has Tropsch synthesis and then downstream product upgrading. DME is one of a suite of fuels that can be produced in the CTL process. It is a product that holds out as ~ domestic fuel. DME generates less carbon monoxide and hydrocarbon air pollution than LPG. It can also be used as an alternative to diesel for transport, and for power applications. The use of DME in combined cycles is a proven technology, and emissions are as low as from natural gas. Where DME replaces domestic coal use, C0 2 emissions may be up to 40 per cent lower. www.sasol.com Courtesy: the energy business, Apri/2010, Pp42-43. reached more than 400 kg/t of cement. In particular, cement manufacturers receive a high number of requests to utilize waste containing chlorine, such as incinerator ash and ash from paper manufacture waste. Incinerator ashes of household wastes have high chlorine content: 1 per cent In the bottom ash and 20 per cent in the fly ash. Agu,-. 1. ~ lllustrttlon of 1 stolcel·type Incinerator. 3