TWI417376B - Method of converting bio-waste into solid fuel by micro-baking reaction - Google Patents

Description

Method for converting biomass waste into solid fuel by microwave induced roasting reaction

The present invention relates to a method of converting biomass waste into a solid fuel, and more particularly to a method of calcining biomass waste to form a solid fuel.

Biomass refers to the biomass on the earth or the organic matter produced by it. It can be converted into solid, liquid and gaseous biomass energy through physical, chemical or biological methods.

At present, heat treatment technologies for converting biomass into biomass energy mainly include combustion, gasification and pyrolysis. For example, the Republic of China Patent No. I281496 discloses a method for converting raw organic resource materials into industrial raw materials, the thermal energy of which is one of saturated steam and/or superheated steam, electrothermal energy or other heat medium fluid, and medium heat energy. Or a hybrid application; US Patent No. 2005/0022553 discloses a method for converting biomass into energy and useful products using a biomass fuel system, which utilizes combustion technology that supplies oxygen to burn biomass in a combustion chamber. U.S. Patent 4,497,637 discloses a method of converting biomass into syngas by cracking the biomass using a cracking technique to form a syngas comprising carbon monoxide and hydrogen.

The calcination reaction of the biomass needs to be carried out in an oxygen-free environment. During the calcination process, the moisture in the biomass, the low molecular weight organic volatiles and the long-chain polysaccharide are removed, and the energy density is high and the abrasiveness is good. Hydrophobic solid product, also known as calcined charcoal or green charcoal. In the past, the calcination reaction of the biomass was carried out by a conventional heating method. The heat was mainly transferred from the outside to the inside of the biomass by conduction, so the heating rate was slow, the required reaction time was long, and more energy was consumed.

Therefore, there is still a need for a method which can greatly shorten the reaction time and obtain a calcined carbon having a high calorific value.

To achieve the above and other objects, the present invention provides a method for converting a biomass waste into a solid fuel by using a microwave-induced calcination reaction, comprising placing a raw material of the raw waste in a microwave reactor; and in an anaerobic condition. Next, the calcination reaction is carried out by microwave heating to convert the raw waste into a solid fuel. The method of the invention is to perform the calcination treatment by means of microwave heating, which can not only effectively increase the calorific value density of the solid fuel, reduce the oxygen/carbon ratio (O/C ratio) of the solid phase product, but also shorten the roasting treatment time. Reduce the benefits of energy consumption.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention from the disclosure. The present invention may be embodied or applied by other different embodiments, and the various details of the present invention may be variously modified and changed without departing from the spirit and scope of the invention.

The method of the present invention performs the calcination treatment of the biomass waste by means of microwave heating, and converts the biomass waste into a solid fuel having a high calorific value density. The method of the present invention uses agricultural and forestry waste as a biomass waste for performing microwave-induced calcination treatment, and examples of the agricultural forestry waste include rice, bagasse, and the like. Before using rice or sugar cane bagasse as raw biomass for microwave-induced calcination, it can be crushed by high-speed pulverizer, dried in an oven at 105 °C, and sieved through a sieve to form dried and broken biomass. Waste materials.

In general, the microwave-induced calcination treatment of the raw material waste material having an excessively large particle size is likely to cause excessive combustion of the air, resulting in a combustion reaction of the reactant, resulting in uneven baking. The smaller the particle size of the raw waste raw material, the larger the bulk density and the contact area between the particles, which helps to improve the heat conduction effect inside the raw material of the raw waste, and greatly increases the overall reaction temperature; on the other hand, if the raw material is produced The particle size of the waste material is too small, and the reaction effect may exceed expectations. As the reaction temperature increases, the fixed carbon component with high calorific value in the solid phase product begins to crack, and the solid fuel formed has a lower calorific value. Therefore, the raw waste raw material used in the method of the present invention does not require excessive energy for grinding, and the raw material particle size is usually preferably between 50 mesh and 100 mesh.

The conversion of biomass waste into a solid fuel by roasting treatment must be carried out in an anaerobic state to avoid a combustion reaction. In a specific example, after the raw material of the raw waste is placed in the microwave reactor, the non-oxygen gas, such as nitrogen, helium, argon or carbon dioxide, is first introduced to replace the air body in the microwave reactor; or the reactor is first withdrawn. The air inside is re-introduced into the non-oxygen gas. After the carrier gas is filled in the reaction chamber, the microwave is started to be calcined, so that the raw material of the raw waste is subjected to microwave-induced roasting under anaerobic conditions. Forming a solid fuel.

In the method of the present invention, the power of microwave heating is too low, the reaction temperature is insufficient, and the raw waste cannot be completely calcined. On the other hand, although the high microwave power can increase the heating rate, increase the reaction temperature, and increase the calorific value of the solid phase product, the overall reaction is less stable and the reaction is less likely to occur. Therefore, the microwave heating of the method of the present invention is generally carried out under microwave power conditions of 150 to 400 W, preferably under microwave power conditions of 250 to 350 W, and different microwave irradiation times are adjusted according to different microwave powers to make the reaction temperature. The calcination reaction is carried out at a temperature of from 200 to 400 °C.

The time of microwave irradiation is shortened as power is increased. According to the analysis results, the content of oxygen in the solid phase product gradually decreases with the increase of reaction time, and the content of hydrogen does not change significantly. On the other hand, if the microwave irradiation time is too long, the carbon element in the solid phase product will be decomposed by the reaction, which is not advantageous for increasing the heat value density of the solid phase product. Therefore, in the method of the present invention, the microwave irradiation time is from 5 to 30 minutes, and the temperature increase rate is preferably not more than 65 ° C / minute.

The method of the invention utilizes microwave heating to carry out the calcination treatment of the raw waste, and the O/C ratio and the H/C ratio of the solid phase product formed by the method of the invention are compared with the calcination treatment of the raw waste by the conventional heating method. The ratio of the decrease is larger and the reaction time is shorter. Among them, in the present invention, the calcined carbon of the rice husk (O element: 43.94%, O/C ratio: 0.99) can be reduced to 30.53%, O/C. The ratio can be reduced from 0.99 to 0.50, the H/C ratio can be reduced from 0.15 to 0.04; the bagasse (O element: 40.45%, O/C ratio: 0.82) is used to roast the carbon, the O element is reduced to 27.95%, and the O/C ratio can be lowered by 0.82. To 0.46, the H/C ratio can be reduced from 0.14 to 0.09, which is more suitable as a high quality solid fuel.

The features and effects of the present invention are further illustrated by the following specific examples, but are not intended to limit the scope of the invention.

Example Example 1

Dry rice was used as raw waste, which was crushed by a high-speed pulverizer, sieved with a 50/100 mesh screen to obtain raw waste materials, and placed in a microwave reactor. Next, nitrogen gas is continuously supplied at a flow rate of 50 ml per minute. After the original air in the furnace is replaced by nitrogen gas, the microwave power is adjusted to 250 W, and irradiation is performed for 8, 10, 12, 20, and 30 minutes, respectively. The microwave induced roasting reaction. After the completion of the reaction, the heat value density of the solid phase product in the microwave reactor was analyzed, and the results are shown in Fig. 1. The content of C, H, and O elements of the solid phase product is shown in Figure 2.

The analysis results show that when the microwave irradiation time increases, the heat value density of the solid phase product also increases. After microwave irradiation for 20 minutes, the heat value density increases by 26%. After microwave irradiation for 30 minutes, the heat value density begins to decrease. The content of C element in the solid phase product reached the highest at 20 minutes after the reaction, and began to decrease after more than 20 minutes, indicating that the reaction time was too long, and the C element in the solid phase product was decomposed by the reaction. The result can also be illustrated. The heat value density changes.

The elemental analyzer was used to analyze the change in the elemental content of the solid phase product. The content of O element decreased gradually with the increase of reaction time, and the content of H element did not change much. According to the results of Figure 2, under the condition of microwave power of 250W, after 20 minutes of irradiation, the O element can be removed, the removal rate is 31%, and the calculated O/C ratio can be reduced from 0.99 to 0.50, and the H/C ratio can be lowered. It drops to 0.04 to 0.15.

Example 2

The bagasse was used as a raw waste, which was crushed by a high-speed pulverizer, sieved with a 50/100 mesh screen to obtain a raw waste material, and placed in a microwave reactor. Next, nitrogen gas was continuously supplied at a flow rate of 50 ml per minute. After the original air in the furnace was replaced by nitrogen gas, the microwave power was adjusted to 250 W for 4, 5, 6, 15, 20, 30 minutes respectively. , microwave induced roasting reaction. After the completion of the reaction, the caloric value density of the solid phase product in the microwave reactor was analyzed, and the results are shown in Fig. 3.

The analysis results show that when the microwave irradiation time increases, the heat value density of the solid phase product also increases. After 15 minutes of microwave irradiation, the heat value density increases by 57%. After microwave irradiation for 20 minutes, the heat value density begins to decrease.

The elemental analyzer was used to analyze the change in the elemental content of the solid phase product. The content of O element decreased gradually with the increase of reaction time, and the content of H element did not change much. According to the results of Fig. 4, under the condition of microwave power of 250W, the O element can be removed after irradiation for 15 minutes, the removal rate is 70%, and the calculated O/C ratio can be reduced from 0.90 to 0.16, and the H/C ratio is lowered. It drops to 0.04 to 0.13.

Example 3

Dry rice was used as raw waste, which was crushed by a high-speed pulverizer, sieved with a 50/100 mesh screen to obtain raw waste materials, and placed in a microwave reactor. Next, nitrogen gas is continuously supplied at a flow rate of 50 ml per minute. After the original air in the furnace is replaced by nitrogen gas, the microwave power is adjusted to 350 W, and irradiation is performed for 4, 6, 8, 10, and 30 minutes, respectively. The microwave induced roasting reaction. After the completion of the reaction, the heat value density of the solid phase product in the microwave reactor was analyzed, and the results are shown in Fig. 5.

The analysis results show that when the microwave irradiation time increases, the heat value density of the solid phase product also increases, and the heat value density increases by 26% after microwave irradiation for 10 minutes. It has also been shown that the use of higher microwave power can shorten the microwave irradiation time and achieve the same baking effect.

Figure 1 is a graph showing the change in the heat value density of the solid phase product of Example 1 of the method of the present invention;

Figure 2 is a graph showing changes in elemental content of solid phase products in Example 1 of the method of the present invention;

Figure 3 is a graph showing the change in the heat value density of the solid phase product of Example 2 of the method of the present invention;

Figure 4 is a graph showing the change in the content of the solid phase product element in Example 2 of the method of the present invention:

Figure 5 is a graph showing the change in the heat value density of the solid phase product of Example 3 of the method of the present invention.

Claims (10)

A method for converting a biomass waste into a solid fuel by using a microwave-induced calcination reaction, comprising the steps of: placing a raw material of the raw waste in a microwave reactor; and performing heat treatment by means of microwave heating to form a solid fuel. The method of claim 1, wherein the raw waste material is heat-treated under an anaerobic condition by introducing a non-oxygen gas. The method of claim 1, wherein the raw waste is rice husk or bagasse. The method according to claim 3, wherein the rice husk or the bagasse is crushed, dried, and screened before being heated by microwaves to form a raw material of biomass waste having a particle size of 50/100 mesh. The method of claim 2, wherein the non-oxygen gas is nitrogen, helium, argon or carbon dioxide. The method of claim 1, wherein the microwave heating is performed under microwave power of 150 to 400 W. The method of claim 1, wherein the microwave heating is performed at a temperature of from 200 to 400 °C. The method of claim 1, wherein the microwave irradiation time is between 5 and 30 minutes. The method of claim 1, wherein the heating rate of the microwave heating is less than 65 ° C / min. The method of claim 1, wherein the solid fuel has an O/C ratio of less than 0.50 and an H/C ratio of less than 0.04.