RU2530057C2 - Method of thermal processing of organic-containing raw material and device for its implementation - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: the method of thermal processing of organic-containing raw materials comprises loading of raw materials and horizontal movement by the piston (2) along the length of the pipe through the chambers of convective drying (3), pyrolysis (4), condensation (5). The liquid fraction (18) and the non-condensed gases (17) obtained in the condensation chamber (5) are discharged, and the solid fraction (19) is cooled and unloaded in the discharge chamber (6). The raw material in the drying chamber (3) is dried convectively, and the ratio n of drying zone length ℓ to the pyrolysis zone length L is defined as $$n=\frac{\mathrm{0,01}W\left(r+\Delta r\right)}{\left(1-\mathrm{0,01}W\right)q_n}\frac{\Delta T_n}{\Delta T_{c}k},$$

where r is heat of moisture evaporation from the free surface, Δr is additional heat loss when drying, kJ/kg ev. moisture; W is moisture of raw material,%; q_n is calorific capacity of dry raw material, kJ/kg; ΔT_n, ΔT_c is temperature difference in the pyrolysis and drying zones, °C; k is the ratio of the weight of solid phase to the weight of raw material. Consumption of worked out drying agent does not exceed the consumption of furnace gases. The device of thermal processing of organic-containing raw materials is provided with furnace gas collector (12) made in the form of an annular perforated part of the pyrolysis chamber with flow section, when fulfilment of condition ΔP_c<ΔP_p, where ΔP_c is pressure loss in the casing with the fan; ΔP_p is pressure loss in the material layer in the pyrolysis chamber (4), and a suction fan (13) with a valve (14) regulating the consumption of worked out drying agent.

EFFECT: invention enables to increase the intensity of the pyrolysis process and to improve the performance of the device.

2 cl, 1 dwg, 1 ex

Description

The invention relates to agriculture and can be used for processing raw materials, mainly in small and agricultural enterprises, as well as in the woodworking industries.

A known method of thermal processing of organo-containing raw materials into gaseous and liquid fuels by heating first in the drying chamber, and then without air in the pyrolysis chamber, followed by condensation of part of the gas-vapor mixture into liquid fuel, and drying is carried out with a mixture of flue gases with air, and part non-condensed vapor-gas mixture , after preheating, is fed into the pyrolysis chamber (patent No. 2395559, IPC G10B, BI No. 1, 2010).

It is also known a device for implementing this method, containing a drying hopper, feeder, reactor, furnace, cyclone, condenser, compressor, gas blower, heat exchanger (RG Khismatov. Thermal decomposition of wood during conductive heat supply. Author. Dissertation. Step. Candidate of Technical Sciences. Kazan, 2010, p.13).

These method and device provide thermal processing of organo-containing raw materials into gaseous and liquid fuels, however, they require developed infrastructure and high capital costs and are unsuitable for small and farmers.

There is a method of thermal processing of agricultural and other wastes into thermal and electric energy, which consists in the fact that the wastes are loaded, horizontally moved, conduction is dried consecutively, pyrolyzed, gaseous products are condensed, the liquid fraction and non-condensed gases are removed, and the solid fraction is moistened and unloaded.

Drying and pyrolysis is carried out by exhaust (furnace) gases from a diesel engine supplied to the casing of the drying and pyrolysis chambers.

A device for its implementation, containing a source of heat, a means of loading raw materials, a piston, conductive drying chambers, pyrolysis, condensation of the gas phase, moistening the solid phase, a means for its unloading, a casing of the drying and pyrolysis chambers that are connected to the heat source (A.V. Golubkovich, A. G. Chizhikov, Justification of the method for calculating the pyrolysis of plant materials // Industrial Energy, No. 12, 2011, p.52-53).

These method and device in their technical essence are closest to the claimed and taken as a prototype.

The disadvantage of this method is the low intensity of the pyrolysis process in connection with inefficient conductive drying.

An object of the invention is to increase the productivity of the device through the use of convective drying of raw materials.

The claimed method can be implemented only in this device.

The problem is achieved in that in the method of thermal processing of organo-containing raw materials by flue gases, which consists in loading the raw materials, horizontally moving them, drying them in series, pyrolyzing, gaseous products are condensed, the resulting liquid fraction and non-condensed gases are removed, and the solid fraction is cooled and unloaded , according to the invention, the raw material is dried convectively, and the ratio n of the length of the drying zone l to the length of the pyrolysis zone L is defined as

,

,

where r is the heat of evaporation of moisture from the free surface, kJ / kg; Δr - additional heat loss during drying, kJ / kg W is the moisture content of the raw material,%; q _n is the calorific value of dry raw materials, kJ / kg; ΔT _n , ΔT _c - temperature difference in the pyrolysis and drying zones, ° C; k is the ratio of the mass of the solid phase after pyrolysis to the mass of raw materials, and the flow rate of the spent drying agent does not exceed the flow rate of flue gases.

The problem is also achieved in that in a device containing a heat source, a means of loading raw materials, a piston, a convective drying chamber, condensation, cooling and unloading of the solid phase, as well as a pyrolysis chamber with a casing, characterized in that it is equipped with a flue gas collector made in in the form of an annular perforated part of the pyrolysis chamber with a live cross section, under the condition ΔР _к <ΔР _p , where ΔР _к is the pressure loss in the casing with a fan; ΔP _p - pressure loss in the layer of material in the pyrolysis chamber, and a suction fan with a control valve, the flow rate of the spent drying agent.

The invention is illustrated in the drawing.

Figure 1 shows a diagram of a device.

The device contains means for loading raw materials 1, piston 2, convection drying chamber 3, pyrolysis 4, condensation 5, unloading 6, unloading means 7, heat source 8, casing 9 of the pyrolysis chamber 4, thermal insulation 10 of the pyrolysis chamber 4, jacket 11 of the condensation chamber 5, a collector 12, a suction fan 13 with a valve 14. In addition, the diagram shows wet raw materials 15, flue gases 16, non-condensed gases 17, liquid fraction 18, solid phase 19, water 20 for cooling the condensation chamber 5 and solid fraction, the drying agent used 21.

The device operates as follows.

Wet raw materials 15 by means of loading 1 are fed into the device, which is made in the form of a pipe and by a piston 2 periodically — they are continuously pushed along the length of the pipe through the chambers of convective drying 3, pyrolysis 4, condensation 5, unloading of solid fraction 6 and the means 7 are removed from the device. The flue gases 16 from the source 8 are fed countercurrent to the casing 9, from it to the convection drying chamber 3 through the collector 12 and suctioned from the convective drying chamber by the fan 13, and the flow of the spent drying agent is changed by the valve 14. The gaseous pyrolysis products are condensed in the chamber 5 by water supply 20 to the jacket 11 and the non-condensed gases 15 and the liquid fraction 18 are removed from it.

In the unloading chamber 6 serves water 20 for cooling the solid phase 19 and then it is used for household needs, as is the water from the jacket 11.

The method is as follows.

The raw materials are loaded, transferred, subsequently convectively dried, pyrolyzed, condensed, non-condensed gases and liquid fraction are removed, and the solid is cooled and unloaded, pyrolysis and drying are carried out by flue gases.

We compose the thermal balances of drying and pyrolysis of raw materials. The amount of evaporated moisture during drying can be written as:

,

,

where G is the capacity of the drying chamber, t; W, W _to - initial and final humidity (relative) of raw materials,%.

влаги, можно записать:The amount of heat required for evaporation $$\overline{W}$$

moisture, you can write:

where r, Δr is the heat of evaporation of moisture from the free surface and additional heat loss during drying, Δr≈0.2 · r, kJ / kg

The amount of heat required for the pyrolysis of raw materials can be written:

where q _n is the specific heat consumption for pyrolysis, which can be approximately taken equal to the calorific value of the raw material, kJ / kg.

The heat expended in evaporating moisture during drying can also be written as:

where Q _g is the consumption of flue gases, kg / h; with ₁ - the heat capacity of the flue gases, kJ / kg · ° C; ΔT _c is the temperature difference in the drying chamber, ° C; τ ₁ - drying time, h

The heat spent on pyrolysis, similarly to (4), we write:

where τ ₂ is the pyrolysis time, h

If there is a backwater from unloading means 7, all chambers will be completely filled, respectively, with raw materials and solid fraction, while the speed of movement of the solid fraction in the pyrolysis chamber will be V ₂ = kV ₁ , where k is the ratio of the mass of the solid fraction after pyrolysis to raw materials; V ₁ - the speed of movement of raw materials in the drying chamber, m / s

Therefore, the ratio n of the length of the drying zone l to the length of the pyrolysis zone L is defined as:

,

,

where l and L are the length of the drying and pyrolysis zone, m

The value of ΔT _n = T _n -T ₀ , where T _{n is the} initial temperature of the flue gases, for example, for a diesel installation T _n ≈400 ° C; T ₀ is the temperature at which the destruction of raw materials begins according to (S.A. Prokopyev. Development of the technology of ultraoxypyrolysis of wood pulp for bio-oil and charcoal // Author. Dissertation for the degree of Candidate of Engineering Science. St. Petersburg, 2007, p. 9) can be taken 140 ° C. At a higher temperature of the flue gases at the inlet to the drying chamber, pyrolysis products may be lost.

The magnitude of ΔT _{c with} write? T = T _n -T _k, where _Tc - temperature of the flue gases at the outlet of the convection drying chamber to backflow conditions, and it is possible _to take T = θ _c + 5 ... 7 ° C, where θ _c - temperature raw materials.

Assuming c ₁ ≈c ₂ , W _to ≈0, equating (2) and (4), (3) and (5) we obtain the ratio:

(6)

(6)

The flue gases from the casing of the pyrolysis chamber enter through the collector 12 into the internal cavity of the drying chamber, pass through a layer of raw materials and are sucked out by a fan 13 in a mixture with water vapor 21.

Efficient and reliable operation of the device is possible if flue gases without gaseous pyrolysis products enter the convection drying chamber. The presence of a layer of material in a pyrolysis chamber of a greater thickness is not a sufficient guarantee that there is no leakage of pyrolysis gases, since defects in the layer structures and various porosity are possible. Equal consumption of flue gases and spent drying agent in this case is necessary.

If the flow rate of the spent drying agent is less than the flow rate of the flue gases, then their excess will be discharged through the flue gas valve 16.

By adjusting the flow rate of the spent drying agent by the valve 14, an economical and efficient operation of the device can be achieved. Manifold 12 is an annular perforated portion, providing a uniform distribution of the flue gases from the pyrolysis chamber living section around the perimeter (ε = 0,2 ... 0,4), when the condition? P _{k <n?} P where? P _k - pressure loss in the casing with collector; ΔP _p - pressure loss in the material layer in the pyrolysis chamber.

Example. Let us determine the ratio of the lengths of the drying and pyrolysis chambers during the thermal processing of plant grain cleaning waste with an initial moisture content of W = 20%. As a heat source, a diesel installation with a power of N = 60 kW with a temperature of exhaust gases T _n ≈400 ° C, the initial temperature of the raw material θ _c = 20 ° C; T ₀ = 140 ° C. The value of τ≈2.5 MJ / kg isp. moisture Δr = 0.5 MJ / kg moisture T _k = 27 ° C; q _t = 12.6 MJ, k = 31 (S. A. Prokopyev. Development of the technology of ultraoxypyrolysis of wood pulp for bio-oil and charcoal // Author. thesis for the degree of Candidate of Engineering Science. St. Petersburg, 2007, p. 9).

According to (6), we obtain n = 0.46.

In conductive drying of raw materials, due to the smaller heat transfer area, the temperature of the flue gases at the outlet of the casing of the drying chamber will be ~ 50 ° C under the assumption that ~ 25% of heat is lost with flue gases and n will be n = 0.54.

Due to the larger volume of the pyrolysis chamber, the productivity of the device will increase by ~ 20%.

Claims (2)

1. The method of thermal processing of organo-containing raw materials, which consists in the fact that the raw materials are loaded, horizontally moved, subsequently dried, pyrolyzed, the gaseous products are condensed, the resulting liquid fraction and non-condensed gases are removed, and the solid fraction is cooled and unloaded, characterized in that the raw material is dried convectively, and the ratio of the length of the drying zone ℓ to the length of the pyrolysis zone L is defined as:

where r is the heat of evaporation of moisture from the free surface, kJ / kg; Δr - additional heat loss during drying, kJ / kg W is the moisture content of the raw material,%; q _n is the calorific value of dry raw materials, kJ / kg; ΔT _n , ΔT _c - temperature difference in the pyrolysis and drying zones, ° C; k is the ratio of the mass of the solid phase after pyrolysis to the mass of raw materials, and the flow rate of the spent drying agent does not exceed the flow rate of flue gases. 2. A device for the thermal processing of organo-containing raw materials containing a heat source, a means of loading raw materials, a piston, a chamber for convective drying, condensation, cooling and unloading of the solid phase, as well as a pyrolysis chamber with a casing, characterized in that it is equipped with a flue gas collector made in in the form of an annular perforated part of the pyrolysis chamber with a live cross section, under the condition ΔP _k <ΔP _p , where ΔP _k is the pressure loss in the casing with a fan; ΔP _p - pressure loss in the layer of material in the pyrolysis chamber, and a suction fan with a valve that controls the flow of the spent drying agent.