In order to utilize cultural waste of mushroom and soybean hull as coke, conversion from dry cultural waste of mushroom (DCWM) and soybean hull (SH) into charcoal by carbonization at 400-800°C, and conversion from them into formed charcoal were investigated. The thermogravimetry tendency of DCWM was intermediate between xylan and lignin, and that of SH was intermediate between cellulose and xylan. Carbonization of DCWM and SH led to make charcoal with high carbon content and higher heating value than raw material. Regarding charcoal carbonized at 800°C, carbon contents of DCWM and SH were 56 and 72%, higher heating values of them were 20.59 and 25.52 MJ/kg, respectively. It was affected by high ash content of DCWM and SH, that carbon contents and higher heating values of these charcoals were lower than coke. On utilization charcoal of DCWM and SH as coke, a preventative method must be taken regarding lower heating value of these than coke. By hot-press forming at 160°C 98MPa from charcoal carbonized at 250°C of DCWM or SH, these charcoal pellets could be produced. And by carbonization at 300-800°C of the pellet formed at 70°C 98MPa from DCWM, carbonized pellet could be produced. In the same manner for producing carbonized pellet of DCWM, the carbonized pellet of SH could be produced, but maximum temperature of carbonization was about 400°C, from the phenomena that puff occur on the pellet in the process of carbonization of it at 500°C. From these results, it is considered effective for increasing energy density of biomass, to convert from raw material into charcoal or formed charcoal.
A batch reactor was made and used in this work. In an actual rapid pyrolyzer/gasifier, each biomass is thrown into high temperature zone in the reactor. In order to simulate the reaction occurred in a fluidized bed rapid pyrolyzer/gasifier, the reactor was designed to inject samples into reaction zone directly and to control the reaction time optionally. Rapid pyrolysis of wood biomasses, such as Konara, bagasse, and EFB (Empty Fruit Bunch), was carried out at 1073K in nitrogen with the reaction time range of 2-20s. Difference in product distribution with varying reaction time was observed apparently among Konara, bagasse, and EFB. The difference in the reactivity among sorts of biomass should be considered even when their elemental composition and/or components ratio are similar. Rapid pyrolysis of wood biomass (Japanese cedar) with small amount of oxygen as gasification agent was also carried out. The amount of product gas was decreased through 1s to 2s and the decreasing rate was higher with increase in the amount of oxygen.
In recent years, much attention has been focused on the energy utilization of biomass to reduce the emission of greenhouse gas. Especially, woody biomass such as the forestry biomass derived from logging and thinning operations in forests is one of the most promising domestic resources in Japan. Woody biomass contributes not only to the improvement of energy self-sufficiency in Japan, but also to the environmental protection of Japanese forests. When the woody biomass is utilized, it is necessary to examine the energy consumption for collection of resources, pretreatment, transportation and after-treatment. In the present study, woody biomass is assumed to be utilized as pulverized wood fuel in local area. The pretreatment of pulverized wood fuel is consisted of three procedures; drying, semi-carbonizaion and fine comminution. The main purpose of the study is to investigate the comminution characteristic of the Japanese cedar thinning and the reduction in energy consumption for pretreatment process and transportation of pulverized wood fuel. The results obtained in the present study are as follows. (1) Comminution energy increases as the water content increases and the sieve of screen becomes small. The comminution energy of hammer mill is largely affected by the water content. Difference in comminution energy between the hammer and cutter mills is large. The ratio of comminution energy of the hammer mill to that of the cutter mill exceeds 10 for the water content of 40% and sieve of screen of 3mm. (2) To estimate the comminution energy of woody biomass, empirical equations of work index in Bond's Law are presented. In woody biomass region, the empirical equations of work index depend on the comminution method. In semi-carbonization and carbonization regions, the empirical equation of work index is presented regardless of comminution method and sieve of screen. The comminution energy can be estimated by using the present empirical equations within accuracy ±50 percent. (3) Analysis of energy consumption for the pretreatment process and transportation is conducted by using the present empirical equations of work index. From the result of analysis, it is found that the semi-carbonization at a temperature of 250 degree C is effective to the reduction in total energy consumption, when the pulverized wood fuel of 300 microns or less in particle size is utilized.
Varieties of technological development for the people support continuing economic activity on the earth are demanded by the problem such as global warming. Expansion renewable energy use as one in this, the observation to biomass is renewable energy resource has risen every year. The suggestion of modeling to simulate the thermolytic behavior is necessary to advance more efficiently energy use by gasification etc. Although the establishment method has not existed yet. This study reports new modeling by statistical approach. The main features of the tried modeling are as follow. The dissipation ratio is the ratio of the loss weight by pyrolysis gasifying and the initial weight. The dissipation ratio of hydrogen, nitrogen and oxygen are proportional to the dissipation of carbon. The dissipation of carbon follows the sigmoid function. The thermolytic behavior of biomass can be analyzed by dividing into cellulose, hemi-cellulose and lignin.
In order to develop a small-scale gasifier in which biomass can be converted to energy with high efficiency, we planned a gasification process that consists of two parts: pyrolysis part (rotary kiln) and gasification part (downdraft gasifier). We performed fundamental experiments on gasification part and discussed the appropriate conditions such as air supply location, air ratio, air temperature and hearth load. We considered the results by calculating reaction rates of representative reactions on char gasification part and found that water gas reaction is dominant in the reduction area and its behavior gives important information to decide the adequate length of the char layer.
In a dual fluidized bed gasifier, the residual char after steam gasification is burnt in riser. The objectives of this work are to clarify the effect of parameters (temperature, pressure, and particle size of lignite char) of char combustion using a laboratory-scale pressurized fluidized bed combustor (PFBC). As a result, the burnout time of lignite char can be improved with increasing operating pressure, and temperature. In addition, the decrease in the particle size of char enhanced the effect on burnout time. The initial combustion rate of the char can be increased with increasing operating pressure. The effect was decreased with increasing operating temperature. However, the effect of operating pressure was slightly changed in small particle size, such as 0.5-1.0 mm. It takes about 20 sec to burn 50% of char in the operating pressure of 0.5 MPa and the particle size of 0.5-1.0 mm.
A new type of circulating fluidized bed gasifier was proposed. The main features of this proposed gasifier are the adoption of a triple-beds structure (comprising pyrolyzer, gasifier, and combustor), the separation of a circulation path for tar-absorbing material and that for the fuel and silica sand. Independent circulation systems are employed for the fuel system and for the tar-absorbing particles, and the pyrolyzer and gasifier each have a two-stage fluidized bed: the lower stage is for the fuel system and the upper stage is for the tar-absorbing system. The two circulation systems each have an independent combustor. This new gasifier is called “a fluidized bed gasifier with triple-beds and dual circulation”. The objectives of this work are to clarify the operation characteristics by using a laboratory-scale cold model. As a result, the stable circulation of the particle in upper and lower stages was able to be verified. Additionally, a wide range of the particle circulation rate, which contains the target value, was obtained. The particle circulation rate can be arranged by pressure drop of riser.