LV11497B - Combustion apparatus and method using only lump fuel where is combined boiler and gas-producer - Google Patents

Abstract

The invention relates to thermal stations (boiler devices), in Latvia known as Goizevski fireboxes, especially to firing devices of various organic fuel and its waste.The essence of the invention: the fuel is gasified in a continuously operating partially depressurised gas generator (GG), supplying it periodically and ensuring practically a constant fill of the GG mine with fuel in height, and a practically constant disposition of zones of fuel burning, dry distillation and drying in it. There are special gas emission vents built in the side wall of the mine between the fuel burning and drying zones, that also serve the function of refinement of combustion products.The invention is applicable in thermal stations (image 2), by combining the partially depressurised gas generator with gas, liquid or solid fuel boilers, that are adapted for burning generator gases.<IMAGE>

Description

Boiler plant with gas-fired head furnace and a method for combustion of all solid fuels therein

Description of the Invention

The invention relates to heating plants (boiler plants), known in Latvia as Goizhevsk furnaces, in particular to various types of organic fuel and its waste incineration plants with a maximum capacity of 10 MW.

The object of the invention is to create a simple and cheap boiler plant with a gas generator (GG) front furnace, to provide complete combustion of fuel and simultaneous flue gas purification using various types of organic fuel (firewood, peat, sawdust, woodchips, wood waste, etc.). content.

Firstly, the choice of a gas-fired type furnace is not accidental, since all types of solid organic fuels can be gasified in gas generators / 1 /. They can be located in close proximity to boiler plants, but the disadvantages of classic gas generators are their complexity and costly construction, as well as the incineration of additional gas or liquid fuels to ensure solid fuel gasification and the need to purify the generator gas. Therefore, in order to achieve the stated goal of creating a boiler plant with a gas generator front furnace, it is necessary to adapt the classical gas generator design to specific needs.

Secondly, there are various furnaces for burning solid organic fuels (2,3), the construction of which depends on the type of fuel combustion, the size of the fractions, the humidity and the capacity of the boiler plants. Constructively, the closest to the idea of a gas-fired furnace is Pomeranceva / pages 2, 98-99 / and Kreicberg / 3, page 306 /, where the fuel is also fed through a vertical shaft, although it does not use the gas-generator principle.

For example, the Kreitzberg firebox consists of a vertical fuel combustion shaft with three full-length holes and horizontal fins at the bottom of the shaft. In the combustion zone, air is supplied both below and above the grates through single row holes. The whole combustion process takes place in the shaft. The perforated shaft walls are also used as vertical bars. For flue gas cleaning behind the furnace, it is necessary to install a purification unit which by its resistance creates additional energy consumption in the flue gas unit. The furnace is intended for incineration of wood waste and can be used in the immediate vicinity of the boiler plant. The temperature in the furnace shaft exceeds 1200 ° C, which shortens the furnace life. There is no secondary air supply behind the furnace.

Thirdly, various technical solutions for heating plants and their units are known, including the BIONER project / 4 / developed by the Finnish company PERUSYHTYMA OY and the so called Goiževskaya furnace / 5 / developed by the author of this application.

Common to these technical solutions / 4.5 / is that:

- solid fuels are used (peat, firewood, sawdust, woodchips, biofuels, hard coal and lignite) with a moisture content exceeding 50%;

- the fuel is wholly or partly gasified in a continuous gas generator (GG) with air and water vapor;

-2- fuel supply and gasification process is continuous;

- the temperature of the ash formation zone is controlled so that the ash remains grained (unsteady, sintered), irrespective of the nature of the fuel and moisture, which allows the ash discharge to be mechanized and / or automated;

- gasification of the fuel and combustion of the resulting gas take place in separate units;

- the gas produced in the generator is transported by pipeline to a gas boiler (GK), which may be distant from GG;

- the gas produced by GG is burned using burners of various designs, the combustion air being supplied by means of a fan;

- the heat of the flue gases is recovered before being discharged into the chimney (one of the types of recovery is the use of an air heater or economizer for heating primary and secondary air and for heating water fed to a steam boiler);

- high efficiency (l.k.) - in all stages / zones irrespective of fluctuations of fuel properties (l.k. over 85%);

- Low dust and polyaromatic hydrocarbon content in flue gases.

The main disadvantages of the BIONER project / 4 /, selected as the prototype of the invention, are the following:

- BIONER (fig. 1) stationary gas generators for complete gasification of fuel; they contain very complex and costly continuous operating equipment; all stages of the process are controlled by microprocessors, etc. automated control and command equipment;

- the technical and technological equipment of the process, which is a trade secret, is not accessible to Latvian users; its development, taking into account local specificities, requires additional research work;

- During operation, all BIONER equipment must be hermetically sealed, except for air supply and gas exhaust systems; this means that during the operation of the plant, the fuel must be supplied and the ash removed from the enclosed space where the generator gas is produced, eliminating the possibility of ash melting;

- special additional gaseous or liquid fuel burners are required for the operation of the main burners.

Nature of the invention (main technical features different to the prototype):

- the fuel is gasified by continuous operation of partially de-pressurized GG with periodic supply of fuel and practically constant height of the GG shaft fill as well as practically constant location of the fuel combustion, dry distillation and drying zones therein;

- the degree of de-pressurization, defined as the ratio of primary to secondary air supplied to GG and GK, respectively, is approximately 1: 1 (± 10%), with approximately half of the primary air being supplied above the GG grate, the remainder below grates;

- Generator gas outlets in the side wall of the GG shaft between the combustion and drying areas of the shaft, which also performs the combustion

-3product purification functions by retaining fine fractions of unburned fuel;

- the required gas temperature in the gas duct between GG and GK is stabilized by partial gas combustion in this duct by suctioning the required amount of air through the fuel inlet hatch; the amount of heat emitted during this process ensures that the entire gas mass is heated and partially burned to such an extent that it does not require the installation of special gas ignition burners at its inlet GK, but in all cases provides its own ignition by supplying only the required amount of secondary air.

Examples of realization of the invention

Example 1. The technological scheme of the process is shown in fig. 2. The construction of the GG shaft with additional openings in the side wall of the shaft is shown in fig. 3. Shaft height - 3.5 m, base - rectangle, which can be of different sizes. Plows horizontal. GG is equipped with humidifier 43 to facilitate ash removal (no slag).

GK, eg gas-fired boiler RK-1,6, equipped with a flue gas fan (smoke extractor). The inclusion of the economiser and air heater in GK equipment depends on the design of the boiler units.

GK is equipped with hardware thermal control parameters. The presence of hardware for automatic control of the process is desirable as it provides better fuel combustion.

Operating temperature of the gasifiable layer:

- at the bottom (in the combustion zone) up to 900 ° C,

- in the middle (in the dry distillation zone): 300 to 800 ° C,

- upwards (in the drying zone) - 150-200 ° C.

The required primary air in the combustion zone of the fuel is provided both above and below the grate without a heat exchanger (preferably with a humidifier).

The generator gas is piped to the GK by stabilizing the temperature of the gas by partially burning it in the pipeline and using the intake air from the fuel inlet for this purpose.

Gas burners use burners that supply secondary air tangentially (~ 5o% of the total amount of air required for the process as a whole) and stabilize the flame with the ignition cone (Fig. 5).

The capacity of the plant is up to 10 MW. The dust content of the dry flue gases is in the range of 40-250 mg / m 3, while the content of polyaromatic hydrocarbons is in the range of 40-120 mg / m 3> or approximately the same as in BIONER technology.

Example 2. The device (Fig. 3) according to the invention consists of a vertical fuel shaft 1 of rectangular or square cross-section. It consists of a masonry 19, a horizontal movable or rigid grate 21, a combustion zone 22, a dry distillation zone 23, a drying zone 24 and a special gas discharge wall 25 made of refractory materials. The furnace shaft has a semi-automatic shutter 26 for fuel reception

-4bunker 27, primary air supply fans 28 and 29 below and above the grates, respectively. The furnace also has secondary air intake and exhaust fans 30 and 31, a generator gas burner with a ignition cone 32, airtight wood supply door 34, an overhead door 16, an ash door 35, 36 and 37, a sight glass 38, a fuel supply unit 2, a boiler 39 , boiler furnace 40, incompletely burned gas passage 42 and ash space 41. The furnace is located in direct or indirect proximity to the boiler.

The fuel in the shaft 20 is fed by means of a conveyor 2 through a hopper 27 with a semi-automatic shutter 26. It is also possible to manually feed the log through the door 33.

In the shaft 20, as a result of the combustion process, the fuel slides down through the drying zone 24, the dry distillation zone 23 and the combustion zone 22. The combustion of the fuel and continuous separation of the ash in the ash space 41 occurs on horizontal fixed or movable grates 21 depending on the ash content. The amount of primary air required for partial combustion is supplied to both the grate 20 and the combustion zone 22 (through openings in the shaft wall in the fireproof masonry wall). Combustion products, generator gas, and minimally sucked air present through the fuel inlet are vented through a special perforated gas outlet wall 25 located in the dry distillation zone to simultaneously purify the flue gases from mechanical impurities and channeled to the GK furnace. At the end of the duct, heated secondary air, in particular through the inlet and outlet openings of the secondary combustion burner 32, is vortexed at the inlet boiler 39 at the furnace 40, providing secondary combustion of the generator gas.

Burner door 34 and ash removal door 35. As a result of the combustion process described above, the amount of ash is reduced by 2 to 3 times.

Doors 36 and 37 provide access to the furnace during repair and removal of ash that may occur during furnace firing. Visual inspection of the combustion process 38.

The 25:25:50 (± 10%) air ratio of recombinable primary (below and above troughs) and secondary air, even at maximum fuel humidity of 60%, provides near nominal heat output (Fig.4) if the GG shaft is continuously fed fueled. The maximum furnace temperature should not exceed 900θΟ. Recommended mesh load 1700.10 ^ kcal / m ^ .h. Exhaust gas velocity through openings 130x130 mm in the shaft wall -10-15 m / s.

When operating this boiler plant in accordance with the described technology, the flue gas is not visible above the chimney.

Description of drawings

FIG. 1 Prototype / 4 / technological scheme (prior art) where: 1 - fuel storage, 2 - fuel feed conveyor, 3 - fuel feed mechanisms, 4 - gas generator, 5 - ash conveyor, 6 - ash conveyor, 7 - ash platform , 8 - drip separator, 9 - humidifier, 10 generation (primary) air fan, 11 - plate heat exchanger, 12 EN 11497

-5 gas pipe, 13 - gas burner with built-in ignition burner, 14 - combustion (secondary) air fan, 15 - gas boiler, 16 - economizer, 17 flue gas fan, 18 - chimney.

FIG. Technological scheme of the invention, wherein: 20-vertical fuel shaft (de-pressurized gas generator), 27 - fuel receiving hopper, 28,29-primary air supply fans below and above the grates, 30 - secondary air supply fan, 39-gas, liquid and / or solid fuel boiler, 41 - ash room, 43 - water spray (spray); the other designations are the same as those in FIG. 1.

Fig.3 One embodiment of the boiler installation according to the invention, wherein: 19 - heavy or lightweight type masonry, 21 horizontal moving or stationary troughs, 22, 23, 24 - combustion, dry distillation and drying zones respectively, 25 - special gas discharge wall made of fireproof materials, 26 - semi-automatic shutter for furnace shaft, 31 secondary air outlet, 32 - generator gas burner with ignition cone, 33 - hermetically sealed wood supply door, 34 - overhead door, 35, 36, 37 - ash door, 38-viewport, 40- boiler 39 furnace, 41-ash space, 42- dehydrated GG (gas generator furnace) connection duct for boiler 39, 43-water spray (humidifier) for humidifying primary air to ensure continuous ash removal and prevent slag formation; the other designations are the same as those in FIG. 1 and 2.

FIG. 4 Range of variation of the power Q according to the invention, depending on the moisture content of the fuel W.

FIG. One embodiment of the boiler plant according to the invention, which is intended to be installed in a boiler house of Naujene, Inciems and Ozolnieki parishes for burning wood waste using boilers RK-1,6 specially reconstructed for burning gas from a generator; the same designations as in FIG. 1-3.

Sources of information

1. Gas generators. Educational tool. RTU Department of Thermal Energy. R., 1990.

2. M.M. lUeronee, tO.n.ryceB, M.C.MBaHOBa KoTenbHbie ycTaHOBKM. M., M3flbo nuT-pbi no CTponTenbCTBy, 1972.

3. CnpaBOMHMK aHepreTMKa pepeBooSpecificTbiBaiomer npepnpMRTMfl. M., 1982.

4. Prospectus of Finnish company PERUSYHTYMA OY: rA3M0MKAUMOHHAR TEnROLļEHTPAJIb CxMraHMe TBepporo TonnMBa c MMHMManbHbiM 3arpyi3HeHMeM 0KpyxaK) meM cpepbi. Mameenlinna, Finland.

5. Technical and technological documentation for installed and operational furnaces;

- SIA MAN-TESS in Riga, Tvaika Street 7 with boilers RK-1, 6 (fuel freshly sawn wood sawdust);

- SIA LINDA at Piebalgs, Vecumnieki village, with boiler E-1-9 (fuel - wood waste);

- Riga region Kekava village with boiler DKVR-6.5-13 (fuel - woodchips, firewood, peat briquettes);

Tukums district Jaunpils village with boiler ΕΡΑΤΟΚ-1Γ (fuel - firewood and milled peat)

Claims (7)

Formula of the Invention 1. Boiler plant incorporating the following units / systems: - a gas-fired (GG) type front furnace with a vertical shaft, grates and primary air supply system providing continuous combustion of the loaded fuel in the lower part of the shaft, dry distillation in the middle of the shaft and drying in the upper part of the shaft; - a system for the removal of GG gas to a gas boiler (GK), which may be remote from GG; - GK equipped with secondary air supply control system, - a control and management system for all stages of the process, characterized in that the front furnace is designed as a partially de-pressurized GG. 2. The apparatus of claim 1, wherein the degree of de-pressurization of GG, expressed as the ratio of primary to secondary air supplied to GG and GK, respectively, is approximately 1: 1 (± 10%), with about half of the primary air is supplied above the grate, the rest under the grate. 3. Apparatus according to claim 1 or 2, characterized in that openings are formed in the side wall of the GG shaft between the combustion and drying areas of the GG shaft for localization of the dry distillation and drying areas and gas collection areas. Device according to claim 2 or 3, characterized in that no special gas ignition burner is installed at the GK inlet and in all cases self-ignition of the gas is provided by supplying said amount of secondary air to the GK inlet. 5. A process for the incineration of all solid organic fuels, characterized in that: - the gas is gasified in a continuous gas furnace (GG) in a continuous operation furnace, providing primary air in the combustion zone of the fuel and regulating the temperature of the ash-forming zone so that the ash remains grained regardless of the type of fuel and moisture, - the generator gas is piped to a gas boiler (GK), gas burners are used to burn the gas, regulating the required secondary air supply, - the heat recovered from the flue gas is used in a variety of process steps, except that GG is de-pressurized by adjusting the ratio of primary to secondary air to about 1: 1 (± 10%) with approximately half of the primary under the grate. -76. A method according to claim 5, characterized by providing periodic fuel supply and ash removal while maintaining a full GG fueled shaft. A method according to claim 5 or 6, characterized in that the desired gas temperature at the end of the gas discharge duct is stabilized by partial combustion of the gas in the duct itself between GG and GK by suctioning the required amount of air through the fuel inlet and shaft. A method according to any one of the preceding claims, characterized in that the secondary air is supplied to the end of the gas supply duct, providing the generator gas with self-ignition without a special ignition burner and stabilizing the gas flame only with the supplied secondary air.