FI79133B - FOERFARANDE FOER UTNYTTJANDE AV PYROLYSGAS OCH PYROLYSANLAEGGNING FOER ANVAENDNING I FOERFARANDET. - Google Patents

Description

1 79133

Method for utilization of pyrolysis gas and pyrolysis plant used in the method

The invention relates to a process for the utilization of pyrolysis gases removed from a plant which produces charcoal by pyrolysis.

FR patent 976559 discloses a process for the production of charcoal and thermal motor fuel by pyrolysis of plant material, in which the pyrolysis apparatus is subjected to thermal cracking of the pyrolignin material, which is supplemented by catalytic cracking. NO patent 68406 describes a space-saving and cost-effective dry distillation apparatus comprising a horizontal, tubular furnace into which the material to be distilled is introduced by grate-bottomed wagons and in which distillation gases are recirculated by fans through the furnace to the longitudinal direction of the distillate.

The utilization of certain wood materials, in particular twigs 20, can be increased by pyrolyzing them to charcoal for various uses. In this case, a pyrolysis apparatus is used, consisting of an elongated, biomass-bed-fired incinerator to which a pipeline is connected for circulating hot gases through said bed. Hot gases can, for example, be generated by a burner mounted above the biomass. The bottom of the incinerator is provided with a permeable part, e.g. a mesh base, which covers the box connected to the suction piping. In this way, the gases are forced through a layer of biomass, whereby they convert the biomass into charcoal, which is removed by a removal device installed at the discharge end of the incinerator. The pyrolysis gases flowing through the charge are removed by a suction piping equipped with a suction fan and connected to a box under the bottom of the net.

35 The pyrolysis gases sucked in this way are burned in a burner above the feed 2 79133 and thus the hot gases required for pyrolysis are obtained. They can also be used to dry the wood prior to loading the material into the pyrolysis equipment.

5 However, per pyrolysis gas stream is sucked in per certain amount of charcoal produced by the pyrolysis plant, which considerably exceeds the need for use.

For example, it has been found that when processing wood with a moisture content adjusted to 15% before the material 10 is fed to the pyrolysis plant and taking into account the flow rate of the gas recycled to the burner of the pyrolysis plant, gas can be sucked into the degassing piping. 3 hxeman more than 1 m V / kg wood, which corresponds to an average lower calorific value (ALA) of 5 3 10 kJ / m V of the gas.

15 When treating 1 tonne per hour of wood with a moisture content of 15%, the required 3 gas streams are recycled to the burner, approx. 1060 m Vn / h pyrolysis gas. It takes only 2.3 x 10 kJ to dry the corresponding amount of wood, which corresponds to just over 400 mv of gas. Thus, about 600 m V of pyrolysis gas with a calorific value of 6 ™ is 3 x 10 kJ per tonne of wood per hour. Until now, pyrolysis gases have been fed to incinerators, boilers or dryers in the vicinity of the pyrolysis plant, because the amount and calorific value of the gas produced have not allowed remote distribution. But in the vicinity of a pyrolysis plant, there are not always plants capable of using the gases produced, especially since, in order to avoid the transport of wood, it is normally sought to char the wood in the vicinity of its splitting site, usually in an area with no other activity.

Also, the charcoal removed from the pyrolysis plant cannot be used in its entirety commercially, because a significant amount of particles, the so-called fines that are wasted today.

3 79133

The object of the invention is to provide a method which makes it possible to utilize both the fines recovered from charcoal and the pyrolysis gases, so that the charcoal-producing plant becomes self-sufficient in energy by means of optimal utilization of the calorific value of the chopped wood.

The process according to the invention is characterized in that a biomass layer is charged to the pyrolysis furnace, that hot gases are recycled through the biomass layer to convert biomass by pyrolysis to charcoal, and for drying the second portion and the biomass and conveying the remaining portion of the pyrolysis gases to a regeneration furnace, wherein the remaining portion of the pyrolysis gases passes through a layer of carbonaceous material consisting of commercially valuable, finely divided particles separated from the pyrolysis kiln; the layer of particles is heated to a high temperature by introducing combustion-maintaining gas into the layer and that the purified, CO-25 and a t 1 -containing lean gas, wherein the lean gas after dewatering can be used to produce at least the energy necessary to maintain the self-sufficient use of the plant.

The invention will be described in more detail by means of an exemplary embodiment and a schematic representation according to the accompanying drawing.

The plant consists of a pyrolysis furnace 1, which in the example described is an elongate, closed space provided with a horizontal or slightly extensible base 11, which at least on the inlet side forms a mesh base 12 covering a box 13 connected to a suction pipe 4 79133. , which consists of e.g. wood chips, is charged via an elevator 31 to a drying oven 32, where a normal water content of about 50% drops to a concentration of 15%. The material 30 thus dried and removed from the dryer 32 is charged via an elevator 33 to the charging hopper 14 of the pyrolysis furnace. In the oven, a device consisting above, hot gases are fed by a burner 16, to which combustion-maintaining gas and fuel are fed. The box 13 is connected via a piping 2 to a suction fan 21, by which the hot gases generated by the burner 16 are forced to pass through the material layer 3. As the moon-15 gases pass through the wood, the charge 3 is pyrolyzed to charcoal, which is removed by a discharge device 17 mounted at the discharge end of the incinerator. -lip gas, hydrogen gas and various vapor hydrocarbons. This gas has the advantage of a considerable calorific value and is thus used as such in the burner 16, into which it is injected through a pipe 22 branching from the suction pipe 2. The suction piping 2 is also connected to another branch 23 branching from it, which leads a second part of the pyrolysis gas to the burner of the dryer 32.

The available part of the pyrolysis gases is removed through the additional branch 25 of the suction piping 2 to the upper-30 part of the shaft furnace 4 for reforming the pyrolysis gases.

The shaft furnace 4 is charged with a layer of carbon material 35, which consists of finely divided particles recovered from the charcoal 34 produced in the pyrolysis furnace. This is done by the removal device 17 leading to a screening device 5 driven by the motor 51, in which commercially acceptable charcoal of size is separated from fine particles having a particle size below a certain limit. The charcoal is transferred to a bagging device 52 and the finely divided particles are transferred via an outlet piping 53 to a storage hopper 54, from which the fines can be dispensed into the furnace 4 to form a layer 35.

The reforming furnace 4 is connected at its lower end via a suction line 6 to a suction fan 61. The suction line 6 is provided with a condenser 62. The pyrolysis gases fed through the line 25 to the top of the shaft furnace 4 and 10 sucked through the line 6 thus flow into the charcoal fines 41. through which heats up to a high temperature, i.e. about 1100-1200 ° C, when air is supplied by means of a fan 43 through nozzles 42.

15 In this way, the hydrocarbons in the vapor space are converted in the furnace 4 into C0 and Idi, and clean gas is sucked through the pipeline 6, which after dewatering can contain about 10% hydrogen and 20% carbon monoxide. As such, this gas can be used in an electrical generating apparatus 20 having a thermal power plant 70, e.g. a piston or gas turbine machine using an AC generator 8. This supplies power to an electrical line 80 which can supply this power not only to all the various motors and fans in the plant. , but also for all the needs of a dormitory marked with the number 81 in the formula.

The composition of the pyrolysis gas sucked through the piping 2 can be, for example, as follows: 5.6% H 2, 3.4% CH 2, 0.6%

Ar, 28.4% N 2, 14.9% CO 2, 7.8% CO, 37.6% H 2 O, 0.37% C 2 H 4, 0.12% C 2 H 6, 0.06% C 2 H 2, 1.15% compounds with an average composition of CgH ^ 02 ·

The average flow rate of the gases sucked through the piping 2 is 1.06 m VR / kg of wood, humidity 15%, which corresponds to an average lower calorific value of the gas of 5 x 103 kJ / m3V.

n 35 Drying the corresponding amount of fresh wood requires n.

6 3 2.3-10 kJ, which corresponds to 460 m V of gas.

n 6 79133

Thus, a branch gas flow of about 600 m V per tonne of wood, 3 n 3 with a calorific value of 4.6 x 10 kJ / m V, is sucked through the branch 25 of the suction piping 2. In the reforming kiln 4, the gases C H are decomposed into hydrogen, carbon-5 monoxide and carbon dioxide and water vapor, and later into methane. Heat demand in this conversion. 5.6 x 10 kJ / m Vn gas. The pyrolysis plant, which consumes 1 ton per hour of wood, produces about 300 kg per hour of charcoal, from which 15 kg per hour-10 ti of commercially worthless fines are recovered. The calorific value of this fines, which is 4.8 x 10 kJ per hour, is quite sufficient for the thermal decomposition of hydrocarbons.

Thus, at the outlet of the shaft furnace, before evaporation and filtration, a gas mixture with an average composition of: 7.77% H 2, 35% N 2, 12.5% CO 2, 14.5% CO, 2.5% CH 4, 27, 8% H 2 O.

The lower calorific value (ALA) of such a mixture is of the order of 4.6 x 103 kJ / m3V.

n After cooling and dehydration, a gas with an average composition of 10.6% H2, 48.5% N2, 17.4% CO2, 20% CO, 3.5% CH4 and a higher calorific value is obtained than 4.6 x 10 3 kJ / 3 6 m V, which corresponds to slightly more than 2.7 x 10 kJ / gas flow of approx. 650 m3V / h.

n 25 But the distribution of electrical power requires that an amount of energy of about 11.7-12.1 MJ be supplied to the equipment generating electricity. Thus, the gas obtained at the outlet of the fan 61 allows the use of an electricity generating apparatus with a power of about 200 kW.

30 Suppose that the whole pyrolysis plant and its accessories, wood dryers, screens, etc. consume approx.

70 kW. This leaves 130 kW, which can be fed into, for example, a sawmill and staff dormitories.

The above calculations for average production thus show that by utilizing the calorific value of wood li 7979133 almost completely, the invention makes it possible to self-utilize the forest by producing charcoal from it in a place that can be completely isolated and / or using the exhaust gases of electricity generating equipment. than-5 for grooming.

It should be noted that the plant has been described by way of example only and that modifications are possible within the scope of the appended claims. In particular, another type of pyrolysis equipment can be used to produce charcoal.

Claims (2)

A process for utilizing pyrolysis gases from a plant which produces charcoal by pyrolysis of biomass, characterized in that a pyrolysis furnace (1) is charged with a layer (3) of biomass, that hot gases are circulated through the biomass layer to convert the biomass through pyrolysis to charcoal (34), which is discharged from the downstream end of the pyrolysis furnace (1), that the pyrolysis gases which have passed the biomass storage (3) are extracted from the pyrolysis furnace (1) by means of a drain pipe network, which consumes part of the pyrolysis gases. generating the hot gases and another portion of the pyrolysis gases for drying the biomass and transporting the residual portion of the pyrolysis gases to a conversion furnace (4), the residual portion of the pyrolysis gases passing a layer (35) of a carbonaceous material, which consists of finely divided particles, which have no commercial value and which are separated from the charcoal (34) produced in the pyrolysis furnace (1), that the layer of the finely divided particles The furnaces are heated to a high temperature by introducing into the layer a combustion-maintaining gas, and a purified, CO- and F-containing poor gas is extracted from the furnace (4), whereby the poor gas after dewatering can be used to generate at least the energy needed to maintain a self-sufficient operation of the facility. Plant for the production of charcoal by biomass pyrolysis, characterized in that it comprises a pyrolysis furnace (1), which is provided with a bottom (11), which includes a permeable part (12), means (14) for charge of biomass at the inlet end of the pyrolysis furnace to form a layer (3) of biomass on the furnace bottom, means (16) for generating hot gases above the biomass layer (3), a pipe network (2) for suction of the