RU82482U1 - INSTALLATION FOR COMBUSTION OF AQUAROGO FUEL - Google Patents

Abstract

The technical solution relates to installations for burning low-grade carbon-containing liquid fuels, mainly water-coal fuels, which in terms of their heat engineering characteristics are low-grade energy fuels due to the high water content. Such installations include boiler plants, furnace devices and other energy-heat-generating plants, operated in compliance with environmental requirements for the combustion process. At the same time, these plants can also be used for the disposal of hazardous waste from various industries added at various stages of fuel combustion, which has low reactivity, explosion and fire safety and, for these reasons, needs a stabilization system for the combustion process in them. The objective is to create a facility for burning low-grade, preferably water-coal, fuel, which provides an increase in the technical efficiency and economy of the process of burning it in heat power plants, for example, boiler plants of small (from 0.5 MW) and medium power (up to 30 MW), in which For structural reasons, it is permissible to use only one NTKS furnace by ensuring stabilization of combustion. The task is achieved by the fact that in the installation for burning coal-water fuel, including a combustion chamber with nozzles for flaring combustion of coal-water, with an air distribution grill for burning fuel, a supply tank for coal-water fuel, connected by a pipeline with nozzles for flaring, a heat exchanger for heating flue gases with blast air,

connected to the pipeline supplying one part of the heated blast air to the flare nozzles, and the other under the air distribution grill, the combustion chamber is additionally equipped with connected nozzles for supplying water-coal fuel to and / or into the low-temperature fluidized bed of inert gas formed on the air distribution grill material in an amount of 15-35% of the total consumption of water-carbon fuel, and nozzles of tangential feed additional of air at the installation in the steady state, and the blast air supply lines formed with regulating devices for the combustion of coal-water fuel gasifying thermal mode or thermal combustion mode. At the same time, control devices are configured to supply blast air to the flare nozzles with an excess coefficient of 1.2-1.3, and into the low-temperature fluidized bed with an excess coefficient of 1.1-2.5 with a thermal combustion mode or with a coefficient excess 0.4-0.9 in the thermal regime with gasification. In addition, with the horizontal layout of the combustion chamber, the nozzles of the flare combustion of coal-water fuel are mounted with the possibility of spraying it in the horizontal direction parallel to the surface of the low-temperature fluidized bed, and with the vertical layout of the combustion chamber, the nozzles of the flare combustion of coal-water fuel are mounted with the possibility of spraying it from top to bottom in the direction center of the low-temperature fluidized bed.

Description

The technical solution relates to installations for the combustion of coal-water fuel, which in terms of its thermal characteristics is a low-grade energy fuel due to its high water content. Such installations include boiler plants, furnace devices and other energy-heat-generating plants, operated in compliance with environmental requirements for the combustion process. At the same time, these plants can also be used for the disposal of hazardous waste from various industries added at various stages of fuel combustion, which has low reactivity, explosion and fire safety and, for these reasons, needs a stabilization system for the combustion process in them.

A known installation for supplying coal liquid fuels to the boiler furnace, including a supply tank, a screw pump, a pneumatic conveying pipe, which includes a section of a heating ribbed pipe located in the flue gas exhaust channel, providing the transfer of water contained in the coal fuel into steam, and a nozzle. Installation works as follows. Using a screw pump, the VUT is fed from a supply tank to the initial section of the pneumatic conveying pipeline, into which compressed air is also introduced. The resulting three-phase mixture: coal powder + water + compressed air is passed through a pneumatic conveying pipeline through

a section of a heating ribbed pipeline located in the flue gas exhaust channel, providing the transfer of water into steam. After that, a two-phase mixture: coal powder + gas, including steam and compressed air, is fed through a nozzle in the form of an aerosol with a temperature of 100-200 ° С to the hot surface of an inert fluidized bed (RU No. 2199060, 2001).

A disadvantage of the known technical solution is the low efficiency associated with increased formation of harmful emissions, the need for its implementation of a constant extraneous supply of thermal energy to a fluidized bed of an inert filler, and low heat stress, since a mixture of coal powder and a vapor-air mixture is fed through nozzles, the surface of the fluidized bed is reached only the most large particles of coal powder. As a rule, the minimum particle size of the coal powder (coal) used in the furnaces of the fluidized bed is such that most of the coal powder should burn in the form of a pulverized coal flame before reaching the surface of the fluidized bed. For these reasons, the use of this installation does not provide a reduction in harmful emissions compared to flare combustion of pulverized coal, since it leads to emissions of nitrogen oxides comparable to flare burning of coal. The content of coal particles of large grades of 1-2 mm in the VUT is not enough to ensure the autothermal regime of the fluidized bed at temperatures of 800 ° -950 ° C, which are necessary for the stable operation of the boiler plant. In this regard, a constant supply of heat to the fluidized bed, not provided for in the known device, is required. The low heat stress of the furnace of the low-temperature fluidized bed (NTSC) also limits the possibilities of the process occurring in it, the possibility of efficiently organizing significant heat removal in which from combustion products with a temperature slightly above the dew temperature of 100 ° -150 ° C (depending

from the sulfur content in VUT) for converting the water included in the VUT into steam.

A furnace device is known - a plant for burning coal-water fuel, including a supply tank, a screw pump, a pneumatic conveying pipeline, and a nozzle for the injection of fuel oil. Installation works as follows. Using a screw pump, the VUT is fed from a supply tank into a pneumatic conveying pipeline into which compressed air is also introduced. The resulting three-phase mixture: coal powder + water + compressed air through a pneumatic conveying pipe through nozzles in the form of an aerosol is fed to the combustion area formed by the nozzle chamber installed in the base of the furnace with an air supply onto which a layer of coarse sand is poured (RU No. 2151953, 1999 )

A disadvantage of the known furnace device is its low processability, efficiency and low heat intensity of the furnace. Low manufacturability is due to the fact that, due to air compressibility, the supply of a three-phase mixture will have a pulsating nature, which will lead to a wide dispersion spectrum of VUT droplets. As a result of this, very large drops of HLW falling into the fluidized bed turn into large ash formations during combustion, in which there is a mechanical underburning of coal, which reduces the economic efficiency of the known method. The smallest drops of VUT do not reach the inert filler layer due to the high speeds of the heated air supply, which ensures the “boiling” of the inert filler, but are carried out by the flow of combustion products outside the fluidized bed and the furnace volume, which also reduces the cost-effectiveness of the known method. features of the known device.

In its technical essence, the closest to the claimed installation is a unit for burning water-coal fuel,

including a furnace for layer-by-layer burning of crushed coal, a consumable tank of coal-water fuel, a pump, burners with nozzles of coal-water fuel, a device for heating blast air with flue gases, a device for separating it into two streams, a device for supplying one part of the stream to the grate (air distribution) grate, and a feeding device for the other part in the burner (Zaydenvarg V.E., Trubetskoy K.N., Murko V.I. and others. The current state of world production and use of water-coal fuel. M .: Nedra. 2001. 184 p.).

This installation works as follows. Crushed coal is burned in a standard lay furnace. Hydrocarbon fuel is pumped from the reservoir to the nozzles spraying it over a layer of burning coal. After heating the blast air with flue gases, it is divided into two parts. One part is sent under the grate (air distribution) grate for layer-by-layer burning of coal, and the other part is fed in the form of a vortex torch for flaring of coal-water fuel, sprayed in the form of a vortex torch, into the combustion chamber above the grate.

A disadvantage of the known technical solution is its low economic efficiency and the technical complexity of the organization of the fuel supply process. This is due to the fact that although with combined flaring of HLW and layer-by-layer burning of coal, the mechanical underburning of coal during layer-by-layer burning is reduced by about half and amounts to about 20%, nevertheless, it significantly exceeds the value of the mechanical burn during the combustion of pulverized coal or the flaring of HLW, which are measured in several percent. Therefore, if we consider the effectiveness of the installation as a whole, then it does not provide the necessary total reduction in mechanical burnout. The complexity of the technological scheme of the organization of the combustion process in the installation is associated with the use of two

type of fuel - solid coal supplied for layered combustion, and liquid - HLF.

The objective of this technical solution is to create a unit for burning water-coal fuel, which provides an increase in the technical efficiency and efficiency of the process of burning it in heat power plants, for example, boiler plants of small (from 0.5 MW) and medium power (up to 30 MW), in which For structural reasons, it is permissible to use only one NTKS furnace by ensuring stabilization of combustion.

The task is achieved by the fact that in the installation for burning coal-water fuel, including a combustion chamber with nozzles for flaring combustion of coal-water, with an air distribution grill for burning fuel, a supply tank for coal-water fuel, connected by a pipeline with nozzles for flaring, a heat exchanger for heating flue gases with blast air, communicated with the pipeline supplying one part of the heated blast air to the flare nozzles, and the other under the air distribution grate, - the combustion chamber is additionally equipped with nozzles for supplying carbonaceous fuel to and / or into the low-temperature boiling layer of inert material formed in the air distribution grill in an amount of 15-35% of the total consumption of water-carbon fuel and tangential feed nozzles connected by a pipeline with a consumable tank of coal-water fuel additional air when the unit is operating in steady state, and the blast air supply pipelines are made with control devices to ensure cross-section during the combustion of coal-water fuel of a thermal regime with gasification or a thermal regime of combustion.

At the same time, the control devices are made with the possibility of supplying blast air to the flare nozzles with

the excess coefficient of 1.2-1.3, and in the low-temperature fluidized bed - with an excess coefficient of 1.1-2.5 in the thermal regime of combustion or with an excess coefficient of 0.4-0.9 in the thermal regime of gasification. In addition, with the horizontal layout of the combustion chamber, the nozzles of the flare combustion of coal-water fuel are mounted with the possibility of spraying it in the horizontal direction parallel to the surface of the low-temperature fluidized bed, and with the vertical layout of the combustion chamber, the nozzles of the flare combustion of coal-water fuel are mounted with the possibility of spraying it from top to bottom in the direction center of the low-temperature fluidized bed.

The use of a low-temperature fluidized bed of an inert material as a burning fuel layer with the use of VUT as a fuel makes it possible to abandon the second stabilization type of fuel, in the prototype, coal during layer combustion. This simplifies the fuel supply system and increases the economic efficiency of the device, since the mechanical burnout when burning fuels in the furnaces of the low-temperature fluidized bed with removal of ash residues from the layer does not exceed one percent. When burning HLT prepared from high-ash coals with an ash content above 20-30% (depending on the grade of coal), this is achieved due to the fact that strong ash residues formed from HLT droplets with an adequate residence time in NTX are almost completely burned out and forced to be removed from him. When burning low-ash HLW, despite the fact that, due to the low mechanical strength, the ash residues are abraded and removed from the bed with combustion products or combustible gases, their effective afterburning is ensured in the flare. The temperature of the low-temperature fluidized bed is within the limits determined by the combustion process of coal, which is part of the coal-water fuel. At the same time, the lower value of the temperature of the fluidized bed in the NTSC ~ 800 ° C is determined by the condition of maintaining the burning rate of the VUT drops at

a level sufficient to completely burn out the organic part of the fuel during its stay in the NTKS and the furnace volume of the boiler. The upper temperature of the fluidized bed in the NTCC should be 50 ° degrees lower than the minimum melting temperature of the mineral part of coal (depending on the grade of coal - from 1000 ° C), which prevents the ash particles from sticking together both in the NTCC and in the furnace volume of the boiler.

The supply of coal-water fuel to the low-temperature fluidized bed is from 15-20% to 30-35% of the total consumption of the fuel-oil mixture. The minimum values of the specified limits relate to HLW prepared from low-ash coals with a maximum heat of combustion of HLW (31-28 MJ / kg). The maximum values of the indicated limits are for HF prepared from high-ash coals with low heat of combustion (18-15 MJ / kg). The value of the minimum supply of HLF to the NTSC is determined from the condition of maintaining a stable combustion mode in the NTKS while ensuring the minimum heat output of the boiler. In these feed modes, the NTKS can operate autonomously, without the flare feed of the fuel-and-chemical assembly with minimal heat output. With the additional supply of HLF for flaring, the heating capacity increases to 100%, that is, it is possible to widely adjust the power of the boiler plant.

The furnaces of the low-temperature fluidized bed allow varying the combustion regimes of the fuel-and-chemical fuel. So, when the coefficient of excess air a is equal to or higher than unity (for example, α = 1.1-2.5), the combustion of HLF occurs with the formation of combustion products in the form of H ₂ O and CO ₂ . In this case, the effect of the NTCC combustion products on the flare is associated mainly with the thermal effect - heating of the medium in which the flare combustion of the fuel-grade fluid occurs. When the coefficient of excess air is less than unity (α = 0.4-0.9), in the mode of gasification of fuel, the composition of the combustion products of NTCC along with H ₂ O and CO ₂ . includes H ₂ and CO, as a result of which, the gaseous medium has

semi-recovery character. In this case, the effect of the NTCC combustion products on the flare is connected both with the thermal effect - heating of the medium in which the flammable fuel is flared - and with the burning of H ₂ and CO to H ₂ O and CO ₂ in the flare ignition zone, which leads to additional heat generation , which means an increase in temperature in the ignition zone of the VUT torch, contributing to its intensification, stabilization and stable operation of the furnace.

With the horizontal layout of the boiler, the spraying of HLF in a plane parallel to the horizontal surface of the HTSC provides the longest residence time of the dispersed drops of HLW in the high-temperature zone of the NTSC.

In the vertical layout of the boiler, a portion of the fuel-and-fuel assembly for flaring from top to bottom in the direction of the center of the NTSC provides the droplets of the sprayed fuel assembly in a spiral, first in the direction of the NTSC and then from it. This approximately doubles the time interval for which the VUT droplets are in the furnace volume of the boiler, improves the combustion conditions of the VUT droplets, and helps to stabilize the VUT droplet burning process.

Figure 1 shows one of the possible technological schemes of a boiler plant for burning water-coal fuel.

The boiler installation contains a supply tank (reservoir) of coal-water fuel 1, a combustion chamber 2, a furnace of a fluidized bed 3 of inert material (not shown in the drawing), a fluidized-bed nozzle 4, a torch-burning nozzle 5, a tangential air supply device 6, an air supply pipe to the nozzles of a fluidized bed 7, a pipeline for supplying spraying air to the nozzles of a flaring 8, a pipeline for supplying air to a furnace of a fluidized bed 9, an air heater - a heat exchanger 10, pipelines 11-13 for supplying carbonic fuel, a pipe water 14 tangential air supply line 15 and common air supply conduit 16 and removal

combustion products. Regulating devices to ensure the supply of blast air into nozzles with various pre-set excess factors can be made in the form of industrial valves calibrated and calibrated in relation to a specific combustion plant

Installation works as follows.

VUT from the supply tank 1 is fed into the pipe 11, divided into two flows, one is fed to the nozzles of the fluidized bed 4, and the other to the flare nozzles 5. The initial ignition of the furnace of the fluidized bed 3 is carried out using, for example, diesel fuel. The air supplied to the atomization, to the fluidized bed furnace and to the flaring, is heated in the heat exchanger 10 by the combustion products leaving the volume of the combustion chamber 2 after cooling in the convection part of the boiler through the pipe 16. A part of the air heated in the air heater 10 is sent through the pipe 9 under air distribution grill of the fluidized bed furnace 3. After the fluidized bed furnace 3 reaches a steady-state thermal mode, in accordance with the specified mode, coal water is fed to the flare burner nozzles 5 and through the pipe 14 into the combustion chamber 2 tangentially serves an additional amount of heated air.

The specific costs of the fuel-and-chemical assembly and the air supplied to the NTSC are determined as a result of the thermal calculation of the NTSC, provided that the temperature of the NTSC is in the range 800 ° -950 ° C.

Table 1 presents the operation parameters of the NTSC experimental furnace in various modes - thermal mode and gasification mode. A VUT with a calorific value of 13.4 MJ / kg (3200 kcal / kg) was prepared from coal enrichment waste from Kuznetsk coal grade SS.

Table 1 mode
parameter Thermal Thermal gasification G _VUT , kg / h 24 36 66 93 α _ntx 1.8 1.7 0.7 0.5 T _ntx, ° С 920

Here: G _VUT kg / h - fuel consumption

α _ntx - coefficient of excess air

T _ntx , ° С - temperature in the layer

The proposed unit for burning coal-water fuel was experimentally tested on a KVR-0.8 boiler with a heating capacity of 0.8 MW at the experimental site of the FSUE Gidrotruboprovod NPO and successfully confirmed the possibility of its operation.

Implementation example.

Table 2 shows the results of the tests performed.

table 2 mode
parameter Thermal Thermal gasification G _NTX , kg / s 25 70 G _ph , kg / s 60 250 β 0.29 0.22 α _ntx 1.8 0.6 α _fact 1.3 1.2 T _ntx, ° C 900 900 T _ph, ° C 1100 1250

Here:

_STAP G, G _factor - the cost VUT through the STAP and flare filing;

_STAP β = G / (G + G _{factor STAP)} - the proportion of fuel supplied to the STAP.

_STAP α _factor and α - an air ratio in the STAP and feeding the flare;

T and T _{STAP factor} - temperature in the STAP and flare.

The blast air was heated in a flue gas heat exchanger. The temperature of the blast air in both cases was 150 ° C. Heated air was divided into two streams. In both modes, the air flow directed to the NTSC amounted to 0.063 kg / s, while the specific air consumption was 9.0 kg per 1 kg of HLW in thermal mode and 3.3 kg per 1 kg of HLW in gasification mode. The air flow directed to the flare amounted to 0.091 kg / s (with a total air flow in the flare of 0.154 kg / s) - in the thermal mode, and 0.471 kg / s (with a total air flow in the flare of 0.534 kg / s) - in the mode gasification.

Hydrocarbon fuel was prepared from coal of the “G ″ brand of the Kuznetsk basin, with a solid phase content in the WUT of 57% and a melting point of ash and slag waste of 1170 ° C. River sand up to 1.6 mm in size was used as an inert material. 0.25 m ² Hydrocarbon fuel dispersed with the help of air in the form of drops was fed through nozzles into the NTKS furnace and dispersed over the area of a fluidized bed of inert material,

From the data given in Table 2, it follows that in the thermal regime the temperature in the flare is kept at a low level, not exceeding the melting temperature of the ash for this coal, which makes it possible to operate the flare furnace without slagging on coal from low-melting coal. At the same time, in the thermal regime with gasification, the temperature in the flare is maintained at a higher level, which helps to stabilize the combustion of fuel oil. Therefore, gasification combustion modes are preferable for HLW with a high water content, a higher ash content and refractory ash and / or coal with a low content of volatile substances such as anthracite, semi-anthracite, and T coal.

It is advisable to use the installation for the combustion of fuel-and-chemical equipment in boilers of small (from 0.5 MW) and medium power (up to 30 MW), in which, for structural reasons, the use of only one NTKS furnace is permissible.

Claims (4)

1. Installation for burning coal-water fuel, including a combustion chamber with flare nozzles for burning coal, with an air distribution grill for burning fuel, a supply tank for coal-water fuel connected by a pipeline with flare nozzles, a heat exchanger for heating flue gases with blast air in communication with a supply pipe parts of the heated blast air into the flare nozzles, and the other under the air distribution grill, characterized in that the furnace to the measure is additionally equipped with nozzles for supplying carbonaceous fuel to a low-temperature fluidized bed of inert material formed on the air distribution grill in an amount of 15-35% of the total consumption of carbonaceous fuel and nozzles for tangential supply of additional air when the unit is operating in a steady state mode, and the blast air pipelines are made with control devices to ensure the burning of water nogo mode fuel gasification or thermal combustion mode. 2. Installation for burning water-coal fuel according to claim 1, characterized in that the control devices are configured to supply blast air to the flare nozzles with an excess coefficient of 1.2-1.3, and in the low-temperature fluidized bed with an excess coefficient of 1 , 1-2.5 in the thermal regime of combustion or with an excess coefficient of 0.4-0.9 in the thermal regime of gasification. 3. Installation for the combustion of coal-water fuel according to claim 1 or 2, characterized in that when the horizontal layout of the combustion chamber, the nozzles of the flare combustion of coal-water fuel are mounted with the possibility of spraying it in a horizontal direction parallel to the surface of the low-temperature fluidized bed. 4. Installation for the combustion of coal-water fuel according to claim 1 or 2, characterized in that in the vertical layout of the combustion chamber, the nozzles of the torch-burning of coal-water fuel are mounted with the possibility of spraying it from top to bottom in the direction of the center of the low-temperature fluidized bed.