RU2761821C1 - Reactor for steam-heat carbonisation of biomass - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the field of public utilities, agricultural production and power engineering, in particular, to apparatuses for steam-heat carbonisation of biomass for the purpose of producing biochar. Proposed is a reactor for steam-heat carbonisation of biomass in a fluidised bed, containing a cylindrical vertical body, a gas distribution grid, an input unit for the initial finely-dispersed raw materials and an output unit for the processed material, characterised by the fact that in order to increase the uniformity of processing of the finely-dispersed material with a simultaneous reduction in the dimensions and mass of the reactor, said vertical inserts providing loop-like movement of the finely-dispersed material, are installed in the gaps between the vertical partitions perpendicular thereto, and the vertical partitions are, in turn, installed along the cross-sectional chords of the cylindrical reactor, wherein each vertical partition is supported by the gas distribution grid and has an outlet for the finely-dispersed material in the lower part thereof in the space between the vertical wall of the reactor and the last vertical insert adjacent to said partition in the course of movement of the finely-dispersed material. Said outlets therein have a diameter of 25 to 40 average diameters of the processed particles, the vertical partitions are installed at a pitch of 0.5 to 0.75 of the height of the layer of particles of the finely-dispersed material in a stationary state, the height of the vertical inserts is 1.5 to 2.5 of the height of the layer of particles of the processed material in a stationary state, the vertical inserts are installed at a pitch of 25 to 40 average particle diameters of the processed particles, and the gap between the vertical inserts and the gas distribution grid is 25 to 40 diameters of the processed particles.

EFFECT: creation of a reactor for steam-heat carbonisation of biomass for the purpose of producing biochar.

1 cl, 2 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to the field of utilities, agricultural production and energy, in particular to devices for steam-thermal carbonization of biomass in order to obtain biochar.

LEVEL OF TECHNOLOGY

Biomass is widely used as a food product or as a renewable raw material for energy production, as well as a raw material for the production of various chemicals and activated carbons. In recent years, this method of processing biomass, as hydrothermal carbonization, began to attract the attention of researchers, due to the possibility of obtaining a solid product, which is called biochar [Z. Liu, F.S. Zhang, Removal of lead from water using biochars prepared from hydrothermal liquefaction of biomass, J. Hazard. Mater. 167 (2009) 933-939, Z. Liu, F.S. Zhang, J. Wu, Characterization and application of chars produced from pinewood pyrolysis and hydrothermal treatment, Fuel 89 (2010) 510-514].

A.B. Fuertes, Hydrothermal carbonization of biomass as a route for the sequestration of CO2: chemical and structural properties of the carbonized products, Biomass Bioenergy 35 (2011) 3152- 3159].The latter can be further used for the synthesis of activated carbon [M. Sevilla, A. Fuertes, R. Mokaya, High density hydrogen storage in superactivated carbons from hydrothermally carbonized renewable organic materials, Energy Environ. Sci. 4 (2011) 1400-1410, M. Sevilla, AB Fuertes, Sustainable porous carbons with a superior performance for CO2 capture, Energy Environ. Sci. 4 (2011) 1765-1771. 802 A. Jain et al. / Chemical Engineering Journal 283 (2016) 789-805, Sevilla, JA

AB Fuertes, Hydrothermal carbonization of biomass as a route for the sequestration of CO2: chemical and structural properties of the carbonized products, Biomass Bioenergy 35 (2011) 3152-3159].

It is noted that the hydrothermal carbonization of biomass makes it possible to obtain biochar with a higher concentration of oxygen functional groups and a low degree of aromatization, which makes the resulting biochar more suitable for further chemical activation [M. Sevilla, A. Fuertes, R. Mokaya, High density hydrogen storage in superactivated carbons from hydrothermally carbonized renewable organic materials, Energy Environ. Sci. 4 (2011) 1400-1410, M. Sevilla, A. Fuertes, The production of carbon materials by hydrothermal carbonization of cellulose, Carbon 47 (2009) 2281-2289].

Biochar is also recommended for use as a clean solid fuel [Zhao P, Shen Y, Ge S, Chen Z, Yoshikawa K. Clean solid biofuel production from high moisture content waste biomass employing hydrothermal treatment. Appl Energy 2014; 131: 345-67, Bach Q-V, Skreiberg ∅. Upgrading biomass fuels via wet torrefaction: a review and comparison with dry torrefaction. Renew Sustain Energy Rev 2016; 54: 665-577, Nizamuddin S, Baloch HA, Griffin GJ, Mubarak NM, Bhutto AW, Abro R, et al. An overview of effect of process parameters on hydrothermal carbonization of biomass. Renew Sustain Energy Rev 2017; 73: 1289-1299, Volpe M, Fiori L. From olive waste to solid biofuel through hydrothermal carbonization: the role of temperature and solid load on secondary char formation and hydrochar energy properties. J Anal Appl Pyrolysis 2017; 124: 63-72], due to a decrease in the moisture content of the obtained biofuel, a decrease in the content of chlorine and nitrogen compounds in it, which reduces harmful emissions during combustion [Zhao P, Shen Y, Ge S, Chen Z, Yoshikawa K. Clean solid biofuel production from high moisture content waste biomass employing hydrothermal treatment. Appl Energy 2014; 131: 345-367].

The hydrothermal carbonization process is implemented in batch reactors and includes the following stages [Chen W-H, Ye S-C, Sheen H-K. Hydrothermal carbonization of sugarcane bagasse via wet torrefaction in association with microwave heating. Bioresour Technol 2012; 118: 195-203, Bach Q-V, Tran K-Q, Khalil RA, Skreiberg ∅, Seisenbaeva G. Comparative assessment of wet torrefaction. Energy Fuels 2013; 27: 6743-6753]:

- loading water and biomass into the reactor in the required ratio,

- heating the reactor to the required temperature with a rise in pressure inside the reactor to prevent boiling of water,

- the process of hydrothermal carbonization for a given time (3-12 hours),

- rapid cooling of the reactor,

- release of pressure and unloading of biochar followed by drying.

From the above, the disadvantages of the hydrothermal carbonization technology are obvious when it is implemented in a known way:

- the frequency of the process,

- the need to use reactors operating under high pressure,

- a large volume of contaminated water that requires further processing,

- long duration of the process and, accordingly, low productivity of the installation or its high metal consumption.

Preliminary studies of the process of hydrothermal carbonization of crushed biomass in a fluidized bed in an environment of superheated steam have been carried out [R.L. Isemin, A.V. Mikhalev, N.S. Muratova, V.S. Kogh-Tatarenko,, Yu. S. Teplitskii, E.K. Buchilko, A.Zh. Greben'kov and E.A. Pitsukha Improving the Efficiency of Biowaste Torrefaction // Thermal Engineering, 2019, Vol. 66, No. 7, pp. 521-526]. This process is called steam thermal carbonation.

Studies have shown that the duration of the process of steam-thermal carbonization in a fluidized bed can be reduced to 15-20 minutes. (versus 4-12 hours when carrying out hydrothermal carbonation using a known technology). At the same time, steam-thermal carbonization makes it possible to obtain biochar, the characteristics of which are comparable to the characteristics of biochar obtained by hydrothermal carbonization methods according to the known technology [B. Ghanim, D. Pandey, W. Kwapinski, J. Leahy, Hydrothermal carbonisation of poultry litter: effects of treatment temperature and residence time on yields and chemical properties of hydrochars., Bioresource Technology 216 (2016) 373-380, P.J. Arauzo, P.A. Maziarka, M.P. Olszewski, R.L. Isemin, N.S. Muratova, F. Ronsse, A. Kruse Valorization of the poultry litter through wet torrefaction and different activation treatments, Science of the Total Environment, 732, 2020, 1-10, 139288].

When carrying out the process of steam-thermal carbonization in a fluidized bed, the problem arises of ensuring the homogeneity of the processing of dispersed material, because the fluidized bed operates in the ideal mixing mode, i.e. after introducing particles of the initial biomass into the reactor, these particles can be immediately removed from the reactor (when the reactor is operating in a continuous mode) long before the completion of the process of their complete thermal treatment.

There is a known reactor for heat treatment of raw materials in a fluidized bed, containing a vertical cylindrical body, a gas distribution grid, an input unit for the initial finely dispersed raw material and an output unit for the heat-treated material, and in the space between the input unit and the output unit there is a spiral vertical insert that excludes the movement of dispersed material from the input unit to the output node on top of the spiral insert and ensuring the movement of dispersed material from the input node to the output node along the surface of the turns of the spiral insert [PG Romankov, NB Rashkovskaya. Drying in suspension. - L. Chemistry, 1979 - p. 150, Figure III.31].

The disadvantage of this reactor is its low efficiency and large dimensions, since at a speed of movement of particles in a fluidized bed of 2-5 cm / s, a very large reactor will be required to provide the required residence time for 15-30 minutes. Otherwise, there is a high likelihood of removing solids from the reactor with a low degree of treatment.

There is a known reactor for thermal treatment of raw materials in a fluidized bed, containing a vertical housing, a gas distribution grid, an input unit for the initial finely dispersed raw materials and an output unit for heat-treated material, and the reactor vessel has a rectangular shape, on the opposite smaller sides of the rectangle there is an input unit for the initial finely dispersed raw material, and along the larger side of the rectangle in the direction of movement of the finely dispersed raw material, there are vertical inserts parallel to the smaller sides of the rectangular reactor vessel, and each previous insert is installed with a gap in relation to one of the large sides of the rectangular reactor vessel, and each subsequent insert is installed with a gap in relation to the opposite large side of the rectangle, the next insert is installed with a gap in relation to the first of the large sides of the rectangular, etc., so that a loop-like movement of ter of the finely dispersed material to be processed from the input unit of the initial finely dispersed raw material to the output unit of the heat-treated material [Romankov P.G., Rashkovskaya NB. Drying in suspension. - L. Chemistry, 1979 - p. 150, Figure III.23].

The disadvantages of this reactor are its large dimensions and high metal consumption, since at a speed of movement of particles in a fluidized bed of 2-5 cm / s, to ensure the required residence time for 15-30 minutes, a reactor with a total path length of fine particles from the inlet to the outlet of 45-90 m is required.Otherwise, there is a high probability of withdrawal from a solids reactor with a low degree of processing.

The closest to the proposed one (prototype) is a reactor for processing finely dispersed raw materials in a fluidized bed, containing a vertical body, a gas distribution grid, an input unit for an initial finely dispersed raw material and an output unit for processed material, and a package of vertical inserts is located in the space between the input unit and the output unit of the processed material installed so that each insert, first in the direction of movement of fine material from the loading unit to the unloading unit, is installed with a gap above the gas distribution grid, the second - without a gap above the gas distribution grid, the third - with a gap above the gas distribution grid, etc., which provides a loop-like movement of the processed particulate material from the loading unit to the unloading unit [Leina Hua, Hu Zhao, Jun Li, Qingshan Zhu, Junwu Wang Solid residence time distribution in a cross-flow dense fluidized bed with baffles, Chemical Engineering Science 200 (2019) 320-335 ].

The disadvantages of this reactor are its large dimensions and high metal consumption, since since at a speed of movement of particles in a fluidized bed of 2-5 cm / s, to ensure the required residence time for 15-30 minutes, a reactor with a total path length of fine particles from the inlet to the outlet of 45-90 m is required.Otherwise, there is a high probability of withdrawal from a solids reactor with a low degree of processing.

The technical objective of the invention is to improve the uniformity of the processing of finely dispersed material during steam-thermal carbonization while reducing the size and weight of the reactor.

SUMMARY OF THE INVENTION

To solve this problem, a reactor for steam-thermal carbonization of biomass in a fluidized bed is proposed, containing a cylindrical vertical body, a gas distribution grid, an input unit for the initial finely dispersed raw material and an output unit for processed material, and in the space between the input unit and the processed material output unit there is a package of vertical inserts installed so that each insert, first in the direction of movement of fine material from the loading unit to the unloading unit, is installed with a gap above the gas distribution grid, the second - without a gap above the gas distribution grid, the third - with a gap above the gas distribution grid, etc., which ensures the loop-like movement of the processed dispersed material from the loading unit to the unloading unit, characterized in that in order to increase the homogeneity of the processing of finely dispersed material while reducing the dimensions and weight of the reactor, the mentioned vertical inserts providing a loop the movement of fine material are installed in the gaps between the vertical partitions perpendicular to them, and the vertical partitions themselves are installed along the chords of the cross-section of the cylindrical reactor, and each vertical partition rests on the gas distribution grid and has in its lower part in the space between the vertical wall of the reactor and the latter in the direction of movement of the finely dispersed material with a vertical insert adjacent to this partition, an opening for the exit of the finely dispersed material. In this case, the said holes have a diameter equal to 25-40 average diameters of the processed particles, the vertical partitions are installed with a step equal to 0.5-0.75 of the height of the layer of particles of finely dispersed material in a stationary state, the height of the vertical inserts is equal to 1.5-2.5 of the height of the layer particles of the processed material in a stationary state, the vertical inserts are installed with a step equal to 25-40 average particle diameters of the processed particles, and the gap between the vertical inserts and the gas distribution grid is 25-40 diameters of the processed particles.

Figure 1 and figure 2 show longitudinal and cross sections of the proposed reactor.

The reactor for steam-thermal carbonization of biomass in a fluidized bed contains a vertical cylindrical body 1, in the lower part of which there is a receiver 2 for superheated water vapor. The reactor contains a gas distribution grid 3, on which a layer 4 of fine particles of the processed biomass rests. For the input of the initial biomass and the output of the processed biomass, there are nodes 5 and 6, respectively. In the reactor 1 there are vertical inserts 7 located in the space between the vertical partitions 8, perpendicular to them. Vertical partitions 8 are located along the chords of the cross-section of the cylindrical reactor vessel 1, rest on the gas distribution grid 3 and have holes 9 for the entry and exit of the processed finely dispersed material.

The reactor for steam thermal carbonization works as follows.

The initial finely dispersed biomass is fed into the reactor 1 through the inlet unit 5 and, after steam-thermal carbonization, is removed through the outlet unit 6. When it moves through the reactor 1, the biomass forms a layer of dispersed material 4 in the reactor, which rests on the gas distribution grid 3 and is brought into a fluidized state using superheated water vapor supplied through receiver 2.

Superheated water vapor has the required temperature sufficient for carrying out the process of steam-thermal carbonization of biomass in a fluidized bed 4.

The initial finely dispersed biomass moves from the input unit 5 to the output unit 6 through the vertical inserts 7, which through one are described on the gas distribution grid 3. The gap between the vertical insert 7 and the gas distribution grid 3 should be 25-40 average diameters of the processed particles. An increase in this ratio leads to an increase in the slip of the untreated material, a decrease in this ratio leads to inhibition of the processed fine material and the creation of stagnant zones.

The height of the vertical inserts 7 is equal to 1.5-2.5 of the height of the layer of particles of the processed material in a stationary state. This ratio is optimal because with a decrease in the height of the inserts, the slip of untreated finely dispersed biomass increases, and with an increase, the movement of biomass is unjustifiably inhibited and the productivity of the reactor for steam thermal carbonization decreases.

Vertical inserts are installed with a step equal to 25-40 average particle diameters of the processed particles. An increase in this ratio leads to an increase in the slip of the untreated material, a decrease in this ratio leads to inhibition of the processed fine material and the creation of stagnant zones.

Vertical inserts 7 are located perpendicular to vertical partitions 8, which are installed along the chords of the cross-section of the cylindrical reactor vessel 1 and have a hole 9 for the exit of fine material. Moreover, said hole 9 has a diameter equal to 25-40 average diameters of the processed particles. An increase in this ratio leads to an increase in the slip of the untreated material, a decrease in this ratio leads to inhibition of the processed fine material and the creation of stagnant zones.

Vertical partitions 8 are installed with a step to each other equal to 0.5-0.75 of the height of the layer of particles of finely dispersed material in a stationary state. This ratio is optimal because when it decreases, piston formation is possible in a fluidized bed enclosed in the space between two adjacent baffles 8. With an increase in the ratio, the dimensions of the reactor 1 unjustifiably increase.

Thus, the required processing time is provided for all the initial particles of biomass, the uniformity of processing increases with a decrease in the size and weight of the reactor.

Claims (1)

A reactor for steam-thermal carbonization of biomass in a fluidized bed, containing a cylindrical vertical body, a gas distribution grid, an input unit for the initial finely dispersed raw material and an output unit for processed material, while in the space between the input unit and the output unit of the processed material there is a package of vertical inserts installed so that each the first in the direction of movement of fine material from the loading unit to the unloading unit, the insert is installed with a gap above the gas distribution grid, the second - without a gap above the gas distribution grid, the third - with a gap above the gas distribution grid, etc., which provides a loop-like movement of the processed dispersed material from the unit loading to the unloading unit, and in order to increase the homogeneity of the processing of finely dispersed material while reducing the dimensions and weight of the reactor, the mentioned vertical inserts, providing a loop-like movement of finely dispersed material, are installed in the gaps between the vertical partitions perpendicular to them, and the vertical partitions themselves, in turn, are installed along the chords of the cross-section of the cylindrical reactor, and each vertical partition rests on the gas distribution grid and has a vertical by an insert adjacent to this partition, an opening for the exit of finely dispersed material, while the said holes have a diameter equal to 25–40 average diameters of the processed particles, vertical partitions are installed with a step equal to 0.5–0.75 of the height of a layer of finely dispersed material particles in a stationary condition, the height of the vertical inserts is equal to 1.5–2.5 of the height of the layer of particles of the processed material in a stationary state, the vertical inserts are installed with a step equal to 25–40 average diameters of the particles of the processed particles, and the gap between the vertical inserts and the gas distribution the casting grid is 25–40 diameters of processed particles.

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