RU2549947C1 - Biomass utilisation plant and method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention describes a structure of a biomass utilisation plant by means of gasification or pyrolysis, in which a vertical cylindrical reactor with a solid particle bed in its lower part, which is provided with devices for supply of biomass and medium under pressure to the solid particle bed, as well as devices for collection of combustible gasification products at the outlet in its upper part, located coaxially inside the annular reactor containing a layer of a granulated catalyst of complete oxidation in its lower part, and provided with a gas-distributing grid and devices for fuel and air supply to a catalyst layer, as well as devices for collection of combustion products, which are located in its upper part. To external surface of the internal reactor there welded are flat ribs from material of the reactor housing, and between branch pipes for supply of biomass and medium under pressure there arranged is a gas-distributing grid above which there located is an organisational head piece, a non-isothermal grid and a heat exchanger, and gaseous gasification products are supplied to the branch pipe for supply of medium under pressure. The lower part of the annular reactor is provided with particles of a catalyser of deep oxidation of substances mixed with disperse particles of inert material, and above the gas-distributing grid there located is the organisational head piece, the non-isothermal grid and the heat exchanger.

EFFECT: increasing productivity as to utilised biomass.

6 cl, 9 ex, 1 dwg

Description

The invention relates to devices and methods for processing waste, mainly biomass, by gasification to produce liquid and gaseous combustible products used as fuel or intermediate intermediates for chemical synthesis or liquid motor fuels.

A known method and apparatus for processing waste (US 6190429, F27B, 20/02/2001) by gasification, comprising the steps of gasifying waste in a fluidized bed reactor at a relatively low temperature, supplying gases and coal obtained in a fluidized bed reactor to a high temperature combustion chamber, obtaining low- or medium-calorie gas in a high-temperature combustion chamber at a relatively high temperature. In a fluidized bed reactor, a fluidized bed with a longitudinal circulation of particles is preferably used. A high temperature combustion chamber can be implemented as a vortex combustion chamber. The temperature in the fluidized bed reactor may be in the range of 450-800 ° C. The temperature in the high temperature combustion chamber can be 1300 ° C or higher. The disadvantages of this method include the high temperature in the combustion chamber (1300 ° C and above), which leads to the formation of a significant amount of nitrogen oxides in flue gases, as well as the complexity of the installation and processing method.

A known method and installation for processing waste by drying, sublimation, oxidation and combustion (US 5806444, F23G 015/00, 09/15/1998). The apparatus for implementing the method includes a furnace with a chamber inside for a fluidized bed of particles, means for recycling the particles of the layer, a device for mixing particles and waste, coating the circulating particles of the layer with waste, drying the waste, means for supplying waste to the furnace from the waste drying device. The invention is applicable to the processing of wet waste, in particular sludge. The disadvantages of the installation for implementing the method is the difficulty of recycling particles of the fluidized bed and the preparation of waste for processing. In addition, the exhaust gases from the installation are polluted by gas emissions resulting from the drying of waste.

A known method of processing biomass or waste and a device for its implementation to produce energy, namely steam and / or electricity by burning biofuel or waste with minimal emissions of harmful or toxic compounds (US 5626088, F23G 007/00, 05/06/1997). The main solutions of the known method include: gasification of biofuel or waste in a circulating fluidized bed gasifier; a standard boiler for burning fuel, having a burner for burning pulverized coal or oil (or natural gas in its lower part), and means for burning gas obtained in the gasifier located above the burner. Biofuels or waste gasify in a fluidized bed, for example, coal ash extracted from the furnace of the boiler, or other solid particles. The disadvantages of the known device and method are the need for additional equipment for cleaning raw gas from gasification from toxic components, relatively high combustion temperatures of 800-1050 ° C in the boiler, which do not prevent the formation of thermal and fuel nitrogen oxides, as well as CO with small excess air during combustion (5 -10%) (especially when burning additional fuel in the form of pulverized coal).

The closest in technical essence is the installation for biomass gasification (RU 76424, F23G 7/00, F27B 15/00, 04/02/2008), including a vertical cylindrical reactor with a layer of solid particles in its lower part, equipped with means for supplying pressure medium (air , vapor-air mixture, inert gas) into the layer of solid particles, as well as means for collecting combustible gasification products located in its upper part. The biomass gasification reactor is located coaxially inside a ring reactor containing a layer of granular catalyst of complete oxidation in its lower part and equipped with a gas distribution grid and means for supplying fuel, for example diesel, and air to the catalyst layer, as well as means for collecting combustion products located in its top. Advantageously, the outlet of the internal reactor (means for collecting combustible gasification products) is further provided with a channel for supplying part of the gasification products as additional fuel to the lower part of the external reactor. Advantageously, the internal reactor is additionally equipped with a cyclone and a container for collecting solid biomass gasification products, and the external reactor is additionally equipped with a cyclone and a container for collecting solid fuel combustion products. In a particular case, the bottom of the internal reactor is made in the form of a cone with an acute angle, for example, 30 °.

The disadvantages of the installation are the small external surface of the gasification reactor, necessary for the transfer of heat from the ring reactor. This leads to an increase in the height of the fluidized bed of solid dispersed particles and catalyst and, accordingly, in the height of the reactors and, as a consequence, to an increase in the energy costs of blowing equipment to ensure boiling of the bed. Additionally, the consumption of dispersed particles and a scarce expensive catalyst for complete oxidation increases. When part of the biomass is burned in a gasification reactor, the gaseous products of gasification are diluted with air nitrogen and their calorific value decreases.

The installation’s disadvantages also include the difficulty of controlling the temperature in the fluidized bed and the heterogeneity of the layer due to gas bubbles, which leads to an increase in toxic substances emissions from flue gases during fuel combustion in a ring reactor and a decrease in the degree of biomass gasification in a gasification reactor.

The problem solved by the present invention is to develop a method and installation for the utilization of biomass, efficiently using heat when burning fuel, ensuring environmental safety of the exhaust flue gas and allowing to reduce the consumption of the catalyst for complete oxidation.

The problem is solved by the design of the installation for biomass utilization by gasification or pyrolysis, in which a vertical cylindrical reactor with a layer of solid particles in its lower part, equipped with means for supplying biomass and pressure medium (air, vapor-air mixture, inert gas) to the layer of solid particles, and also means for collecting combustible gasification products at the outlet in its upper part, located coaxially inside a ring reactor containing a layer of granular catalyst for complete oxidation in its the bottom part, and equipped with a gas distribution grill and means for supplying fuel and air to the catalyst bed, as well as means for collecting combustion products located in its upper part. Flat ribs from the material of the reactor vessel are welded to the outer surface of the internal reactor, and a gas distribution grid is located between the nozzles for supplying biomass and pressure medium, over which the organizing nozzle, non-isothermal grid and heat exchanger are located, and gaseous gasification products are sent to the pipe for supplying pressure medium . The ring reactor in the lower part contains particles of a deep oxidation catalyst mixed with dispersed particles of an inert material in a ratio of 20-90 wt.% Catalyst and 10-80 wt.% Inert material, and an organizing nozzle, a non-isothermal grate, and a heat exchanger are located above the gas distribution grid.

The problem is also solved by the method of biomass utilization by using the above installation.

In FIG. depicts a setup diagram for the disposal of biomass.

The installation consists of a reactor 1 with a gas distribution grid 2, onto which dispersed particles are loaded 3. Above the gas distribution grid 2, an organizing nozzle 4, a non-isothermal grid 5 and a heat exchanger 6 cooled by water are located. On the outer surface of the reactor, flat ribs are welded 7. Above the gas distribution grid 2 below the organizing nozzle 4 is the input of the biomass supply device 8. The gases after leaving the upper part of the reactor 1 are separated from the solid products in cyclone 9, and the liquid products are condensed in the heat exchanger 10. After the heat exchanger 10 with a gas blower 11 gasification gases are partially supplied under the gas distribution grid 2. The reactor 1 is located coaxially inside the ring reactor 12. The reactor 12 is also equipped with a gas distribution grid 13, on which the particulate layer 14. The complete oxidation of the catalyst under a gas distribution grid 13 is introduced air. Above the gas distribution grid there is a fuel (liquid) inlet 15, a portion of the gasification gas part 16 and an apparatus for supplying solid gasification products 17, an organizer nozzle 18, a non-isothermal grate 19 and a heat exchanger 20 are located in the upper part of the reactor, a flue gas outlet 21 and further means for cleaning flue gases from dust 22.

Installation works as follows.

The layer of particles of the catalyst for complete oxidation 14 in the reactor 12 is heated by an external heat source to a temperature of 300-350 ° C. Then, under the gas distribution grid 13, air is supplied to the catalyst bed, which brings the bed to a fluidized state and, at the same time, fuel is dosed into the bed through the device 15. The temperature in the layer rises to 700-750 ° C. After that, the external heat source is turned off. The temperature in the layer is regulated by fuel consumption. The presence of the organizing nozzle 18 allows you to completely oxidize the fuel to a non-isothermal grate 19. Depending on the parameters of the non-isothermal grate 19, the temperature in the upper part of the fluidized bed is kept below the temperature of the fluidized bed under the grate due to heat removal by the heat exchanger 20 above the grate 19, which reduces the temperature of the bed and the waste from the flue gas reactor in the limit to the temperature of condensation of water vapor, for example 100 ° C. The heat released in the fluidized bed of the catalyst of the reactor 12 is transferred through the wall and ribs 7 to the reactor 1 and heats the dispersed particles layer 3. After reaching the working temperature in the reactor 12, an inert gas is supplied under the gas distribution grid of the reactor 1 by gas blower 11, for example, flue gases after cyclone 22 through valve 23. Excess flue gases are discharged through valve 24. After the oxygen has been displaced from reactor 1, cyclone 9 and heat exchanger 10, valve 23 is closed and Tween 8 is fed biomass. In layer 3, organized by nozzle 4, biomass gasification occurs. The temperature in the layer 400-750 ° C is supported by the consumption of biomass, as well as heat removal when heating the water in the heat exchanger 6 above the non-isothermal grate 5. The products (solid, liquid and gaseous) released during gasification of the biomass from the reactor 1 are sent for separation into a cyclone 9 and a heat exchanger 10. After cyclone 9, solid products are sent for combustion in the reactor 12 or for disposal, for example, as an adsorbent or enriched solid fuel or for disposal (with the complete conversion of biomass to mineral ash). After the heat exchanger 10, the liquid products are sent for combustion in the reactor 12 or for processing to obtain energy or motor fuel. The gaseous products after the heat exchanger 10 are sent for combustion in the reactor 12 or for processing as raw materials for chemical synthesis, for example, motor fuel.

The invention is illustrated by the following examples, table and FIG.

Example 1

In the installation depicted in Fig., Spend the disposal of biomass gasification by rapid pyrolysis. Softwood sawdust with a moisture content of 10% is used as biomass. The diameter of the internal gasification reactor is 1-60 mm. The diameter of the outer ring reactor is 12-122 mm. In the reactor 12 is loaded alumina-copper-chromium catalyst for the complete oxidation of CuMgCr ₂ O ₄ / Al ₂ O ₃ with an average diameter of granules of 1.5 mm Under the gas distribution grid 13 serves air in an amount of 28 m ³ / h The height of the fluidized bed in the reactor 12 to a non-isothermal grating is 0.5 m. Granules of river sand with an average diameter of 1.3 mm are loaded into the reactor 1. Under the gas distribution grid 2 serves an inert gas in an amount of 10 m ³ / h (flue gases after cyclone 22 or gasification gas). The height of the fluidized bed in reactor 1 to a non-isothermal grate is 0.5 m. Above the gas distribution gratings in reactors 1 and 12, organizing nozzles are placed in the form of a packet of gratings made of wire with a diameter of 3 mm with a clear cell of 20 mm and a distance between the gratings of 30 mm. The height of the nozzles is 300 mm. Non-isothermal gratings are placed above the organizing nozzles in the form of a packet of gratings made of wire with a diameter of 3 mm with a cell in the light of 10 mm and a distance between the gratings of 10 mm. Nozzle height 60 mm. Above the non-isothermal gratings are placed tubular coil-type heat exchangers cooled by water. On the outer wall of the reactor 1, heat exchange fins 7 are welded with a thickness of 5 mm and a height of 15 mm with a total surface of 0.16 m ² . The catalyst layer in the reactor 12 is heated to a temperature of 300 ° C by heating the air with an external electric heater. Then, diesel fuel is started to be dosed into the layer of the reactor 12 and the temperature in the layer is brought up to 700-750 ° C due to the heat of combustion of the fuel. Then, sawdust begins to be fed into reactor 1. In the reactor 1 set the temperature to 500 ° C by changing the flow rate of the supplied sawdust. At the outlet of the reactor 12, the content of CO and nitrogen oxides in the flue gases is recorded. At the outlet of the reactor after the heat exchanger 10, the content of CO, CO ₂ , CH ₄ , H ₂ in the gasification gases and the amount of liquid products formed are recorded. After cyclone 9, the amount of solid products formed after gasification is recorded.

Data on the composition of gasification products are given in the table.

The maximum biomass capacity is 25.2 kg / h at a temperature in the reactor of 12 - 700 ° C, and in the reactor 1 - 500 ° C. The CO content in the flue gases after the reactor is 1 - 10 mg / m ³ , NO _x - 5 mg / m ³ .

Example 2

Similar to example 1.

Heat transfer ribs 7 are removed from the outer wall of reactor 1. The maximum biomass productivity of reactor 1 decreases to 10.1 kg / h.

Example 3

Similar to example 1.

The organizing nozzle 18 is removed from the reactor 12. The concentration of CO in the flue gases after the reactor 12 increases to 40-60 mg / m ³ .

Example 4

Similar to example 1.

The organizing nozzle 4 is removed from the reactor 1. The maximum biomass productivity of the reactor 1 is reduced to 22 kg / h.

Example 5

Similar to example 1.

Into reactor 12, 20% by weight of CuMgCr ₂ O ₄ / Al ₂ O ₃ catalyst and 80% by weight of river sand are charged. The CO content in the flue gases after the reactor is 1 - 10 mg / m ³ , NO _x - 5 mg / m ³ .

Example 6

Similar to example 1.

10% by weight of CuMgCr ₂ O ₄ / Al ₂ O ₃ catalyst and 90% by weight of river sand are charged to reactor 12. The CO content in the flue gases after the reactor 1 increases to 40 mg / m ³ .

Example 7

Similar to example 1.

In the reactor 1 load the catalyst CuMgCr ₂ O ₄ / Al ₂ O ₃ . The amount of non-condensable gases increases to 23.3% (table).

Example 8

Similar to example 1.

The reactor γ-loaded catalyst γ-Al ₂ O ₃ . The amount of non-condensable gases is reduced to 5.7% (table).

Example 9

Similar to example 1.

The reactor 12 is maintained at a temperature of 750 ° C. In the reactor 1 maintain a temperature of 700 ° C. Under the gas distribution grid 2 serves gasification gas 5 m ³ / h and water vapor 5 m ³ / h In the reactor 1 load the catalyst CuMgCr ₂ O ₄ / Al ₂ O ₃ . The content of non-condensable gases increases to 61.1% (table).

Table The composition of gasification products in wt. % Example Number Carbon residue Liquid products Non-condensing gases (CH ₄ , H ₂ , CO, CO ₂ ) one 27.4 62.7 9.9 7 26,4 50.3 23.3 8 27.3 67.0 5.7 9 2.7 36,2 61.1

As can be seen from the above examples, the proposed installation allows you to save the height of the fluidized bed and, accordingly, the energy costs of the blasting equipment to increase the maximum productivity of the utilized biomass. At the same time, the amount of the scarce and expensive catalyst for complete oxidation is sharply reduced. Additionally, when using catalysts for biomass gasification, it is possible to control the composition of gasification products.

Claims (6)

1. Installation for utilization of biomass by gasification or pyrolysis, comprising a vertical cylindrical reactor with a layer of solid particles in its lower part, equipped with means for supplying biomass and pressure medium, such as air, vapor-air mixture, inert gas, into the layer of solid particles, and also means for collecting combustible gasification products at the outlet in its upper part, located coaxially inside a ring reactor containing a layer of granular catalyst for complete oxidation in its lower part, and equipment The gas distribution grid and means for supplying fuel and air to the catalyst bed, as well as means for collecting combustion products located in its upper part, characterized in that flat ribs from the material of the reactor vessel and between the nozzles for supplying biomass are welded to the outer surface of the internal reactor and a medium under pressure there is a gas distribution grill, over which there is a layer of solid particles, an organizing nozzle, a non-isothermal grill and a heat exchanger, and in the nozzle for the hearth As a result, gaseous gasification products are directed under pressure. 2. Installation according to claim 1, characterized in that the ring reactor contains particles of a catalyst for the deep oxidation of substances mixed with dispersed particles of an inert material in a ratio of 20-90 wt.% Catalyst and 10-80 wt.% Inert material, and above the gas distribution grid The organizing nozzle, non-isothermal grill and heat exchanger are located. 3. Installation according to claim 1, characterized in that in the internal reactor the layer of solid particles contains a catalyst for the decomposition or synthesis of hydrocarbons or carbon conversion by water vapor. 4. The method of biomass utilization by gasification or pyrolysis in a fluidized bed of solid particles in a ring reactor located coaxially inside a ring reactor containing a fluidized bed of a granular catalyst of complete oxidation, characterized in that the process is carried out in the installation according to any one of claims 1 to 3. 5. The method according to claim 4, characterized in that the particles of the deep oxidation catalyst are mixed into a ring reactor in a mixture with dispersed particles of an inert material in a ratio of 20-90 wt.% Catalyst and 10-80 wt.% Inert material. 6. The method according to claim 4, characterized in that a layer of solid particles of a catalyst for decomposition or synthesis of hydrocarbons or carbon conversion with water vapor is loaded into an internal reactor.

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