Biomass solid fuel

1. A molded-then-torrefied biomass solid fuel obtained by a method comprising molding pulverized biomass particles into unheated biomass blocks and then torrefying the unheated biomass blocks in a furnace, without performing a steam explosion, wherein mutual bonding or adhesion between pulverized biomass particles is maintained after immersion in water, and wherein the molded-then-torrefied biomass solid fuel has a chemical oxygen demand (COD) of 3000 ppm or less, and wherein at least one condition selected from the group consisting of the following conditions (a3) to (f3) is satisfied:

condition (a3): the raw material of the pulverized biomass particles is rubber tree and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.43 m 2 /g to 0.80 m 2 /g;

condition (b3): the raw material of the pulverized biomass particles is acacia and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.32 m 2 /g to 0.60 m 2 /g;

condition (c3): the raw material of the pulverized biomass particles is meranti and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.30 to 0.45 m 2 /g;

condition (d3): the raw material of the pulverized biomass particles is eucalyptus and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.135 m 2 /g to 0.210 m 2 /g;

condition (e3): the raw material of the pulverized biomass particles is teak and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.355 m 2 /g to 0.550 m 2 /g; and

condition (f3): the raw material of the pulverized biomass particles is a mixture of larch, spruce and birch and the molded-then-torrefied biomass solid fuel has a BET specific surface area of 0.150 m 2 /g to 0.250 m 2 /g.

2. The molded-then-torrefied biomass solid fuel according to claim 1 , having a fuel ratio (fixed carbon/volatile matter) of 0.15 to 1.50, dry-basis higher heating value of 4500 to 7000 (kcal/kg-dry), a molar ratio of oxygen O to carbon C (O/C) of 0.1 to 0.7, and a molar ratio of hydrogen H to carbon C (H/C) is 0.70 to 1.40.

3. The molded-then-torrefied biomass solid fuel according to claim 1 , having an equilibrium moisture content after immersion in water of 10 to 65 wt %.

4. The molded-then-torrefied biomass solid fuel according to claim 1 , having a diameter expansion ratio after immersion in water of 20% or less.

5. The molded-then-torrefied biomass solid fuel according to claim 1 , having a length expansion ratio after immersion in water of 10% or less.

6. The molded-then-torrefied biomass solid fuel according to claim 1 , having a volume expansion ratio after immersion in water of 160% or less.

7. The molded-then-torrefied biomass solid fuel according to claim 1 , having COD (chemical oxygen demand) of 43 ppm or more.

8. The molded-then-torrefied biomass solid fuel according to claim 1 , wherein at least one condition selected from the group consisting of the following conditions (a1) to (f1) is satisfied:

condition (a1): the raw material of the pulverized biomass particles is rubber tree and the molded-then-torrefied biomass solid fuel has COD of 2200 ppm or less;

condition (b1): the raw material of the pulverized biomass particles is acacia and the molded-then-torrefied biomass solid fuel has COD of 400 ppm or less;

condition (c1): the raw material of the pulverized biomass particles is meranti and the molded-then-torrefied biomass solid fuel has COD of 460 ppm or less;

condition (d1): the raw material of the pulverized biomass particles is eucalyptus and the molded-then-torrefied biomass solid fuel has COD of 730 ppm or less;

condition (e1): the raw material of the pulverized biomass particles is teak and the molded-then-torrefied biomass solid fuel has COD of 1300 ppm or less; and

condition (f1): the raw material of the pulverized biomass particles is a mixture of larch, spruce and birch and the molded-then-torrefied biomass solid fuel has COD of 950 ppm or less.

9. The molded-then-torrefied biomass solid fuel according to claim 1 , wherein at least one condition selected from the group consisting of the following conditions (a2) to (f2) is satisfied:

condition (a2): the raw material of the pulverized biomass particles is rubber tree and the molded-then-torrefied biomass solid fuel has COD of 110 ppm or more;

condition (b2): the raw material of the pulverized biomass particles is acacia and the molded-then-torrefied biomass solid fuel has COD of 47 ppm or more;

condition (c2): the raw material of the pulverized biomass particles is meranti and the molded-then-torrefied biomass solid fuel has COD of 43 ppm or more;

condition (d2): the raw material of the pulverized biomass particles is eucalyptus and the molded-then-torrefied biomass solid fuel has COD of 110 ppm or more;

condition (e2): the raw material of the pulverized biomass particles is teak and the molded-then-torrefied biomass solid fuel has COD of 260 ppm or more; and

condition (f2): the raw material of the pulverized biomass particles is a mixture of larch, spruce and birch and the molded-then-torrefied biomass solid fuel has COD of 330 ppm or more.

10. The molded-then-torrefied biomass solid fuel according to claim 1 , wherein at least one condition selected from the group consisting of the following conditions (a4) to (f4) is satisfied:

condition (a4): the raw material of the pulverized biomass particles is rubber tree and the molded-then-torrefied biomass solid fuel has COD of 2500 ppm or less;

condition (b4): the raw material of the pulverized biomass particles is acacia and the molded-then-torrefied biomass solid fuel has COD of 400 ppm or less;

condition (c4): the raw material of the pulverized biomass particles is meranti and the molded-then-torrefied biomass solid fuel has COD of 550 ppm or less;

condition (d4): the raw material of the pulverized biomass particles is eucalyptus and the molded-then-torrefied biomass solid fuel has COD of 900 ppm or less;

condition (e4): the raw material of the pulverized biomass particles is teak and the molded-then-torrefied biomass solid fuel has COD of 1500 ppm or less; and

condition (f4): the raw material of the pulverized biomass particles is a mixture of larch, spruce and birch and the molded-then-torrefied biomass solid fuel has COD of 1200 ppm or less.

11. The molded-then-torrefied biomass solid fuel according to claim 1 , wherein at least one condition selected from the group consisting of the conditions (a3), (c3), (d3), (e3) and (f3) is satisfied.

12. A method of manufacturing the molded-then-torrefied biomass solid fuel according to claim 1 , comprising:

molding the pulverized biomass particles into unheated biomass blocks, and

torrefying the unheated biomass blocks without performing a steam explosion to obtain a torrefied solid product, wherein the torrefied solid product is used as the biomass solid fuel; wherein

the torrefying temperature is 150° C. to 400° C., a raw material of the biomass comprises at least one selected from the group consisting of rubber tree, acacia, meranti, eucalyptus , teak, and a mixture of larch, spruce and birch, and

the molded-then-torrefied biomass solid fuel has fuel ratio (fixed carbon/volatile matter) of 0.15 to 1.50, dry-basis higher heating value of 4500 to 7000 (kcal/kg-dry), a molar ratio of oxygen O to carbon C (O/C) of 0.1 to 0.7, and a molar ratio of hydrogen H to carbon C (H/C) is 0.70 to 1.40.

13. The method of manufacturing a biomass solid fuel according to claim 12 , wherein B/A=0.6 to 1 is satisfied, wherein A is a bulk density of the unheated biomass blocks and B is a bulk density of the heated solid product.

14. The method of manufacturing a biomass solid fuel according to claim 12 , wherein H2/H1=1.1 to 4.0 is satisfied, wherein H1 is a HGI (Hardgrove grindability index) of the unheated biomass blocks and H2 is a HGI of the heated solid product.