FI120217B - A method and a feeder for controlling mixing conditions in a combustion or gasification plant - Google Patents

Description

The present invention relates to a method of the kind defined in claim 1. The invention relates to a method of adjusting the mixing conditions in an incineration or gasification plant.

The invention also relates to a feeder for performing the method.

Qualitative and quantitative gas analyzes are increasingly needed in connection with different types of existing combustion and gasification processes. Nitrogen oxides are the most interesting flue gas components of interest today, especially given the charge introduced in Sweden for installations with a capacity of more than 10 MW and an annual production of more than 50 GWh.

This efficient, energy limit will most likely be lowered as requirements increase for other types of flue gas components, such as C0 and N20 (il gas).

•: · Most existing incinerators are designed so that all unwanted jets smoke • · · ί.ί! it is very difficult to achieve minimal concentrations of the gas components at the same time. In other words, "Compromise solution and", for example, high CO content. * · *. low NO content, cannot be avoided in these systems.

• · · • · * · • · · · ·. - 3b Fuel composition often varies from one operating mode to another, particularly with regard to different types of waste.

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fuels and also wood fuels.

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Examples of ash and / or slag rich fuels include wood fuels, straw, wastes such as industrial, household, environmentally hazardous and chemical wastes as well as coal, lignite, peat, lime and 5 black liquors. This category of combustion / gasification systems also includes crematoria and cement kilns.

The term "ash" refers to an inorganic or non-combustible material originally contained in a fuel.

The term "slag" refers to inorganic and non-combustible materials such as "additives" in metals, ceramics, glass, stone, etc. The term "ash" is often included in the term "slag". Examples of non-ash and / or slag rich fuels are oil, natural gas, LPG and certain biofuels.

Fuel price is another important parameter for optimizing flue gas or gas parameters. Fuel ... the sulfur content and, to a certain extent, the nitrogen content are • · · * · 'directly proportional to the emission level before the flue gas cleaning system. The result of course is that • · • · · ·. *: The price of fuel rises when, for example, the nitrogen content of • · ·. * ·· 25 is lower. Of course, the market price, which sometimes changes rapidly, also affects the financial performance.

• Emissions trading under the so-called bubble models are systems that are • • · expected to break through in the market in the future.

• · · · · · · · ·

The above parameters indicate the need for flexible combustion / gasification systems that are fast !!!!: 35 adjustable to achieve the most economically advantageous operating point in each situation.

3 With this type of optimization, the perforated tubes in the combustion or gasification chamber are fed with a medium comprising gas or liquid or possibly solid particles. Examples of gases are air, 5 oxygen, oxygen enriched air, flue gas, inert gas (CO2, N2, etc.), post-combustion fuel (LPG, natural gas, ethanol, etc.), NOx reducing agents (NH3, urea, etc.), and steam with flow, pressure and temperature. Examples of liquids are water, NH3, urea, ethanol and other organic solvents, etc.

Examples of solid particles are biofuel, including peat, coal and waste (plastics, etc.), the resulting powder. These can be used as post-combustion fuel.

The oxidizing agents present, for example air, must oxidize non-flammable gases, such as CO, while reducing agents, such as NH3 or, for example, LPG, must, under various conditions, reduce N0, to the desired degree.

• * Place the pipe or pipes in a suitable place for burning / draining: * ·.! to develop optimum conditions.

. ·. : 2 5 • · · • ·. . ·. For example, in a "top fire" grate boiler with a burner • · · • · ·. the air under the substance causes the flue gas to flow upwards, • the pipe or pipes may be placed above the grate ... at the first draft of the boiler. Nk. In the case of the "bottom" 30 combustion process, the opposite is true.

For example, for a fluidized bed with a variable • · · ·; ***; pressure, pipe or pipes may be placed in the combustion chamber, • · · *. for example, above the bubble layer.

• · ·

Combustion / gasification of fuels nowadays takes place in many different types of equipment and installations in the form of furnaces, furnaces, etc. with burners, arinoids, fluidized and / or bubble layers, etc.

5 One of the features of such ovens and furnaces is that e.g. The flue gas emissions of CO, CxHy (hydrocarbon), NOx, SO2, N20, dioxin, PAH are often very high due to poorly combustion optimized plants. Some plants are also equipped with different types of flue gas purification systems, such as electrostatic precipitators or textile filters, SCRs, scrubbers, etc., which are located downstream of the incinerator, which reduces the level of emissions in the subsequent flue / gas duct.

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EP-0 286 077 A2 (Mtill-Verbrennungsanlage Wuppertal) discloses, as an example of well-known devices for minimizing emissions, a process for incinerating waste in which flue gases are sucked out of the furnace and introduced into a rotary motion by adding secondary air.

Secondary air is supplied through the nozzles so that the flow of flue gases • · ·: * in the constant zone of the furnace .. * · * is slowed down and then allowed to linger there for about 8 seconds.

• · - *: 25 • ·. SE, C, 139 072 (Larsson) discloses a furnace specifically designed for heating boilers or for connection to furnaces ... of the same type in boilers in which primary air inlets are located. 30 in the sides of the furnace, which inlet leads to one or more • · **; · * fixed tubes along the furnace, which in turn *: * include a rotatable tube that allows the air to be adjusted by turning the tube around its axis and / or • · · *. moving the tube axially.

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DE, C, 107755 (Lindemann) discloses a device for supplying air above a fuel bed 5, which has a tubular grate having mesh-superposed tubes and side openings so that a plurality of air jets intersect.

5, SE, C, 115 046 (Sinding) discloses a device for preheating and regulating secondary air supplied to furnaces, which is provided with concentric tubes disposed adjacent and extending into a preheating chamber for supplying air to the chamber 10 and being rotatable. with each other such that the openings therein can be angled relative to each other to adjust the passage area and thus the air supply.

For example, feeders in the form of a perforated tube for injection into the combustion chamber are known from WO-A1-91 / 00134 (Fuel Tech Europe), 15 US-A-4 883 003 (Hoskinson) and SE, C, 139 563 (Svenska Maskin-Verken). .

Other examples of prior art are disclosed in SE, C, 45212 (Reck) and SE, B, 458147 (Lantmännen Odal).

• * ·:. * Patent Publication FI-B-87014 (Tampella) discloses a device for feeding granular lime by means of a gas stream instead of • · ί / .j. To feed lime, use a tubular: *. a device for moving the nozzle. The lime is fed to the fireplace at a location that is • • · suitable for the temperature in the flue gas stream. The specification of claim 1 la of the appended claim relates to a process of this type, which may be considered to be the closest prior art.

• · · · ··· *: * None of the above methods and facilities allow for careful optimization of the combustion process so that the combustion or gasification chamber can provide reliable adjustment or adjustment to process variations. by.

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In addition, none of the known systems allows to influence the mixing situation or mixing ratio of the combustion gases and / or these, and the media fed to the combustion chamber, the media supplied.

Accordingly, it is an object of the invention to minimize interference with known combustion and gasification processes and associated plants, thereby increasing the combustion efficiency of the gasification process and reducing emissions.

Another goal is to increase the flexibility of the method and plant to enable quick and simple adjustment from one desired emission level (e.g. high CO and low NO) to another (e.g. low CO and high NO) when needed, depending on the economic output. .

Yet another object is to provide a method of minimizing disturbance nights, respectively, a feeder that simplifies and lowers the cleaning of the pipes, thereby improving the yield of the combustion process.

Another objective is to provide a method, apparatus, • 25 which makes it possible to use the combustion process. continuously or at least almost continuously, i.e..

• · · without interrupting the process to remove soot or to purify, for example, secondary air-fed pipes located in the combustion chamber.

These and other objects are achieved by the method of the present invention, which is similar to the one described above and which. the main features are shown in the characterizing part of claim 1.

··· 35 * * The displacement of at least one of the tubes shown results in a more efficient mixing of the feed medium with the combustion gases 7, allowing for more efficient combustion and optimization of current flue gas or gas parameters. Thus, with the invention, it is possible to select the best mixing situation or mixing ratio for each combustion process.

As shown, the same or different media, for example of the aforementioned type, can be fed through co-operating tubes. For example, it is possible to supply afterburning fuel, which improves the chances of controlling the temperature profile in the combustion chamber.

In order to improve mixing, it is considered appropriate that the tubes 15 for changing the speed, flow pattern and direction of the medium are further rotated about their longitudinal axes.

In this case, it is considered appropriate that the tubes are displaced and / or rotated by the impulses generated by the sensors, which are located outside the chamber and recognize the combustion chamber.

Different types of sensors can be used for this purpose, such as temperature, pressure, flow, •. sensors for flue gas components, etc. present. Optical sensors can also be used for this * · · • · · * purpose.

··· • · · 30 The signals generated by the sensors can also be used to control the supply of solid medium particles to the tubes, · · · · · · · · · · · · · · · · · · · · · · · · · · ·. executed in beats or intermittently. The rotation of the perforated tubes ensures that, if desired, the »1« ••• J 35 feeds at predetermined, variable angles within the combustion chamber.

8 In practice, it is recommended that the tubes be moved by means of holding and actuating means located outside the chamber and preferably communicating with the ends of the tubes, so that the tubes can be completely withdrawn from the chamber.

It will then be possible to combine the cleaning operation with the pull-out operation preferably so that the mechanical brushes or the like are in contact with the outer surface of the tubes 10 to clean them of the soot and other adhered particles during the pull-out operation.

According to one embodiment, the tubes are pulled out into the dead-earth position outside the chamber by the action of one or more impulses generated by one or more sensors which activate the extraction mechanism, for example, in the event of a power outage or power failure.

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In addition, the tubes are preferably mounted interchangeably in a holding and actuating member disposed outside the chamber.

In this case, very simple adaptation to the different operating conditions of the plant · · Σ / ·· will be possible, which can thus be achieved simply by changing it; · *; Sat one or more feed pipes. It is clear that the system also facilitates plant repairs and maintenance, which also reduces costs.

In general, the method according to the invention can be applied to existing combustion plants as well as to new combustion plants. New boilers fireplaces! ***: Can be manufactured with a smaller firebox volume, • · · due to more efficient gas mixing, which reduces costs. In this case, the optimum operating conditions at the optimum emission level in each case can be achieved by • · 9 much simpler than previously known systems.

In addition, a cooling medium may be added to lower the temperature of the tube jacket 5 so that slag or other type of particle deposits on the tube become such that the cleaning of the tubes is facilitated or the number of cleaning operations is minimized.

Such a cooling medium may optionally be fed separately, possibly intermittently and preferably in connection with the withdrawal of the tubes. Preferably, it is fed through an annular slot surrounding each tube. By cooling, slag and other particulate deposits on the tubes become less glassy or sticky, which simplifies and speeds up the cleaning process.

The present invention also relates to a feed device for adjusting the mixing situation or ratio to optimize the flue gas and gas parameters of the medium fed to the combustion or gasification plant 20, wherein The features are set forth in claim 8.

Preferred embodiments of the feeder are defined in the appended claims.

• · • · · · «» ··

Other features of the method and feeder of the invention, respectively, are set forth in the following description ... of some preferred embodiments of the invention. At the same time, reference is made to the accompanying drawing, in which: Fig. 1 is a perspective view of a partially cut-off solid fuel incineration plant, is provided with a feeding device according to the invention.

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Fig. 2 is a side elevational view of a feed device according to the invention comprising perforated tube and means disposed outside the combustion chamber for moving, twisting, adjusting and cleaning the tube. In the figure, the tube is shown in a position introduced into the combustion chamber.

Fig. 3 is a side view corresponding to Fig. 2 with the feeder fully withdrawn from the combustion chamber.

Fig. 4 is a sectional view taken along line IV-IV in Fig. 3.

Fig. 5 is a horizontal sectional view of the combustion chamber showing its three co-operating feeders located on one plane to enhance mixing of the medium with the combustion gases.

Fig. 6 is a schematic elevational view of an alternative embodiment in which a plurality of different feeding devices for the medium are disposed in an "in-line" turret holder located outside the combustion chamber for optional introduction into the combustion chamber.

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In Fig. 1, reference numeral 1 denotes a combustion plant which comprises a furnace 2 for combustion of solid fuels with a grate 3 and an upper combustion chamber 4.

The fuel can be supplied intermittently or continuously. . ·. and the combustion air is blown as primary air from below and • · · «··. • j ·. up through the grate 3.

• ♦ ♦ ... Secondary air is supplied through a plurality of ♦ · · 30 feeders in accordance with the present invention which project into the combustion chamber 4 through special openings in the furnace wall 5 and are described in more detail below. secondary

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air is supplied through said feeders to the gas and • · · ·. to complete the combustion of the formed reaction products in the form of solid particles.

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The particles in the flue gas above the grate 3 consist of ash, slag and / or non-combustible fuel. These may together form larger particles, so-called agglomerates, or may be reduced to smaller, more or less pure ash particles. Flue gases of richer fuels often contain higher concentrations of particulates and slag.

Some of the particles form deposits on the inner wall of the combustion chamber 10, which is often provided with pipes 6 with external insulation. Dust particles also accumulate on the tubes 13, whereby the openings 13a for supplying secondary air are completely or partially blocked, which affects the supply of secondary air, or the deposition 15 occurs directly on the casing surface of the tube.

This causes incomplete combustion, which is not optimal and causes additional problems of this type.

20 Poor mixing conditions in this type of gas chamber reduce the combustion efficiency of the incinerator. This: **: is particularly evident when measures are taken to reduce NOx ··· when non-flammable gases / particulates

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concentrations are higher than before adjustment.

• ·. ·. : 25 The air inlet and / or flue gas recirculation in the oak tree reduces the temperature in the combustion zone and, in addition, develops reduction conditions leading to lower concentrations of N0X- and higher levels of non-combustible gases and particles. Efficient secondary air mix ··· • · · _.

In this case, the requirement of V * 30 dewatering becomes even more important, which ··· * ... · in turn leads to the requirement to perform frequent cleaning or soot removal of the secondary air ducts.

In the plant shown in Fig. 1, the supply pipes 13 for the medium, for example · ♦ * ~ _ ... 5 3b secondary air, are arranged so as to form a curtain system which comprising a plurality of tubes 13, some of which are parallel to 12, to one or more planes in the combustion chamber 4. The tubes 13 are provided with holes 13a located along the entire casing surface of the tubes. The holes may be spaced apart and a row of holes may be located on each side of each respective tube.

The through-flow area of the holes 13a determines the fluid flow at a given pressure. When the velocity profile across the cross-sectional area in question often varies within the combustion or gasification plant 10 where the device is to be installed, compensation must be made when the media are supplied.

The medium, for example high-pressure secondary air, is supplied by a fan 10 connected to a manifold-15 box 11, which is connected to flexible tubes 12 which are connected via quick couplers to the end flanges 13b of the tubes 13. The opposite ends of the tubes may be closed or provided with outlet openings (not shown).

Depending on the combustion process in question, the tubes 13 are introduced into or withdrawn from the chamber 4 in the axial direction ·· · j * ^ 1 at longer or shorter intervals. In this way, the emissions of the ··· combustion process can be kept at an optimum level.

• · · · · · · · · · · · · ·. : 25 Figures 2 and 3 show the mechanisms used to · · · • ·. ·, For transferring the tubes 13 inside the combustion chamber 4, respectively.

• · · 111 to pull it out and rotate it, steer it, and clean it.

··· • · · BO Pipes 13 are housed in a housing 14 which supports some of the said mechanisms. To move the tube, use .j. an electric motor 16 whose drive shaft drives a circular disk • · · ·. ···. size 17. The endless belt or chain 20 is guided around the disk and • · • also around the rollers 18, 19. Attached to the belt 20 is a ··· 35 carrier in the form of a carriage 25 which engages the 13 ends of the tube ***** to form the base 25b so that the 13 tubes can simultaneously be rotated about its longitudinal axis. The holder 25 is movably guided by the guide 26.

In Figure 2, the tube 13 is shown in the position introduced into the combustion chamber 5, while in Figure 3, the tube is completely withdrawn from the chamber. The holder 25 is then arranged such that the tube 13 can be easily replaced in the retracted position.

The electric motor 27 drives a belt 28 which extends over a plurality of rollers 29 which are in contact with the circumferential surface of the tube 13 to rotate it.

As shown in Fig. 4, the holder 25 is provided with fork-15-shaped arms 25a which support the base 25b on which the tube 13 rests. The holder or carriage 25 is movably guided by a guide 26.

The front end of the housing 14 is connected to the housing 30, into which opposing guide rollers 15 for the tube 20 and also a system of steel ridges 21 are disposed, between which the tubes pass as they are pulled out and subsequently inserted. These brushes 21 efficiently clean the pipes to remove dust and slag deposits.

• · I · »» · · ···

It is evident that the system shown will greatly »» · pot the pipes to be cleaned and that the tubes may be pulled out ... one at a time or a few at a time while the combustion process continues because, for example, secondary air »* ' ··· * is fed through pipes still in the combustion chamber.

···> ···; *** · Alternatively or additionally, an automatic • · · * can be connected. shaker (impact mechanism or similar, not shown); or

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35 acoustic soot remover (infrared or ultrasonic) for continuous or intermittent slag removal.

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Figure 5 illustrates how the flow pattern of the medium fed through adjacent tubes 13 can be altered, in part by moving one or more tubes at different locations in the combustion chamber 4 and partly by rotating or rotating 5 one or more tubes. Further, such an effect can be achieved by varying the pressure, velocity and / or flow of the feed medium. As shown in Figure 5, different mixing conditions can be achieved as a result of the media flow flows of adjacent tubes 10 being able to reinforce or reinforce each other, to more or less extinguish each other, or to cause an effect between them.

Post-combustion fuel such as ethanol can be fed through one, two, or all tubes 13 to provide a temperature profile, i.e. temperature in different zones of chamber 4, can be adjusted to achieve optimum combustion process.

Figure 6 illustrates a "revolver system" in which the housing ... 14 is replaced by a housing 14 'which rotates about axis 40 and has a plurality of media supply tubes in which holes 13a are formed with each other • · • · · *. *: Distances and locations differ.

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To cope with various combustion conditions in chamber 4, housing 14 'is rotated such that the medium supply tube 13, which is most appropriate in the prevailing situation, is introduced into combustion chamber 4. Bellows-like tubing 12' is attached to the ends 13 of the tubes 13. • · "* feed into each tube.

In practice, the length of the tubes 13 may vary from 1 to 2.:. m to 5 m and diameter from 120 mm to 200 mm. Reikien * * * * - _, M1; 35 The diameter of the 13a can range from 1-2mm up to 2-4mm, and the distances between • · holes can vary from 10cm to 40cm.

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In addition, the control of the medium supplied to each tube 13 can be accomplished by means of signals from sensors 5 (not shown) for different gas parameters, gas concentrations, temperatures, pressure, flow, etc. These sensors can also be used, for example, via a computer, to determine when to start a cleaning or soot removal procedure. As mentioned above, there is no need to interrupt the incineration process. In Fig. 1011, reference numeral 42 denotes a sensor of this type.

Reference numerals 43, 44 designate an optical sensor, wherein reference numeral 44 relates to a lens. For example, in the event of a power outage or power failure in the plant coolant supply, one or more sensors detect this and send an impulse to pull the tubes into an inactive position outside the chamber. This is a very important security measure within the basic idea of the invention.

The installation of the invention in the combustion chamber results in ... better combustion results with lower concentrations of NOx, CO, N2O, hydrocarbons and non-combustible particles as well as dioxin · · · · ····.

The plant with the feeder according to the invention is easy to install and, as a result, particularly suitable for fireplaces, incinerators and gasification plants already in operation or already on the market. the conversion.

·· 1 2 ♦ ♦ ♦ • · ♦. ***. 30 The tubes need not be horizontal in the combustion chamber.

• · ··· • Thus, one or more tubes may be in an inclined position or may be in an upright position.

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Claims (10)

A method for adjusting mixing conditions in a combustion or gasification plant by means of a feed additive fed through a feeder to optimize flue gas or gas parameters, wherein said plant has a combustion or gasification chamber (4) which is provided with an axially displaceable tube for feeding or for maintaining the gasification process 10, characterized in that at least one of the two or more perforated tubes (13) is moved at longer or shorter intervals in the axial direction of the chamber (4) to effect a predetermined controlled mixing of the media with the combustion gases. Method according to Claim 1, characterized in that the tubes are moved from the outside of the chamber (4) by means of a retaining and actuating means (25; 16, 20), preferably acting on their ends, so that the tubes can be completely withdrawn from the chamber. «» »• ♦ · • · • ♦ Method according to Claim 2, characterized in that the tubes (13) are pulled out into an inactive position 25 outside the chamber by one or more sensors transmitted by the sensor. signal, which activate the extraction mechanism in the event of, for example, a power failure or a power failure in the plant cooling medium. ··· • · · A method according to any one of claims 1 to 3, characterized in that the tubes are further twisted about their longitudinal axis by the pressure, the structure of the flow • · · ·: ***; and / or to change direction. • · · «· · Method according to one of Claims 1 to 4, characterized in that the tubes are moved and / or twisted by the impulse transmitted by one or more sensors (42, 43, 44) located outside the chamber and the combustion situation in the chamber is detected. 6. A method according to claim 2, characterized in that the pipes are interchangeably arranged in connection with the holding and operating means. Method according to one of Claims 2 to 6, characterized in that the pipes are cleaned when they are pulled out. A feeder for adjusting mixing conditions by means of a fluid fed to the combustion or gasification plant for optimizing the flue gas or gas parameters, said plant comprising a combustion or gasification chamber (4) having an axially displaceable tube through which the medium is fed to the , characterized by two or more axially displaceable tubes (13) in the chamber (4); A holding device and actuator (16, 20; 26; 15) communicating with the ends of one or more tubes (13) in the chamber ··· '* · *. (4) externally to move the pipes in a predetermined, adjustable · · · · · * · manner to influence the mixing of the medium • · • · ~ - • *: 25 persons of fuel gas through mutual interaction between the pipes; and ·· «, ϊΣ a device (e.g., 42-44) for controlling the movement of the time and / or combustion space detected in the chamber '· *; subject to. 30 The feeding device according to claim 8, characterized by a ·· device (27, 28, 29; 21, 38, 39) for twisting and / or cleaning the pipes. · ♦ · 35 io. Feeding device according to Claim 8 or 9, characterized in that the holding and operating means are arranged such that they allow the tubes (13) to be completely withdrawn from the chamber and to be replaced. • • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·