JPS5839468B2 - Vertical gasifier that operates continuously and its operating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuously operated vertical gasifier and a method of operating the same.

The use of steam in furnaces is well known.

Steam is used for two purposes.

That is, firstly, it is used as a means for cooling,
Secondly, it is used as a means to promote more effective combustion of the fuel or charge to be combusted.

Steam, air, and carbon are combined in a high-temperature furnace mix (fur
When present in nacemix), an endothermic reaction proceeds,
The result is highly flammable reaction products, including hydrogen and carbon monoxide, which burn in the presence of oxygen, producing intense heat that is transferred to the fuel or load being combusted. Promotes more efficient combustion of materials.

A furnace that utilizes an endothermic reaction of the supplied steam as a cooling means, or a furnace that utilizes an exothermic reaction due to combustion of a highly flammable reaction product as a more effective combustion means, or a furnace that utilizes an endothermic reaction of the steam. Furnaces that combine cooling and exothermic reactions are known.

The above two effects have been used in furnaces by providing separate steam introduction devices at different locations within the furnace to achieve specific objectives.

While furnaces that use steam have the sole purpose of those furnaces to burn fuel or other materials, the present invention relates to the gasification of waste.

Traditionally, when steam and air are used in a furnace,
There has always been interest in methods of injecting or delivering steam and air into a furnace.

This interest is evidenced by the desire to control either the endothermic or exothermic reactions of the steam in the furnace and to obtain a homogeneous mixture of air and steam.

In a sealed, continuously operating furnace, a double tilting valve is used to ensure a tight seal and evacuate the ash from the furnace.
A mechanical device such as a tipping valve is used.

Such devices typically have dual seals to maintain one seal while discharging the ash.

Another mechanical device is a cone that rotates eccentrically above the furnace outlet.

The cone supports the charge layer and agitates the charge as the cone rotates, causing ash to fall from between the cone and the furnace wall into a sealed hopper.

It is desirable to avoid moving mechanical ash evacuation equipment in the immediate vicinity of the furnace body and outlet to allow for repairs and replacement without significantly affecting furnace operation. .

According to the invention, the ash hopper of the furnace is such that the ash in this hopper supports the layer of charge and no mechanical support devices are provided in the furnace or attached to the outlet. Designed to.

The invention makes it possible to continuously discharge ash from the gasifier without having to provide any movable mechanical equipment in close contact with the furnace outlet.

The present invention will now be described in detail from various angles with reference to the accompanying drawings.

The invention will be understood by those skilled in the art by reference to FIG. 1, which is a cross-sectional view of a preferred embodiment of the furnace of the invention, which is, for example, a continuously operating vertical gasifier.

The furnace of FIG. 1 is shown only as an example for explaining the present invention, and the type of furnace of the present invention or the applicability of the furnace of the present invention should not be limited by the furnace illustrated in FIG. isn't it.

The basic furnace of the invention has three parts: a feed part 7;
It can be divided into a main body part 8 and a discharge part 9.

These three parts of the furnace are supported by a superstructure 10.

The feed section 7 of the furnace has a charging port 12 and a device for feeding the charge into the charging port 12, such as a conveyor belt 13, for example.

A charging hopper 14 is arranged adjacent to the charging port 12, and at least two rollers 15 are arranged between the hopper 14 and the main body 8 of the furnace.

A trap door (tr) is provided between the roller 15 and the main body 8.
apdoor) 17 or a sealing gate or other suitable sealing device may be provided.

The conveyor belt 13 mounted on the superstructure 10 is
It is arranged to bring the charge to the charging port 12.

Since the furnace should be sealed from the surrounding air, charging port 12
A device is provided for sealing.

One such device is an inlet gate 34 that can be closed when no charge is being fed by the conveyor belt 13, thereby forming a seal at the furnace charge 12.

Hopper 14 receives the charge coming through charging port 12.

Bridging of the charge in hopper 14
g) In order to prevent this, rocking devices such as movable walls 35 are provided.

The charge moves from the hopper 13 past at least two rollers 15 and then through the furnace inlet 23 into the furnace chamber 2.
Sent into 2.

A device 38 is provided for controlling the spacing between the two rollers.

The spacing between the two rollers 15 is such that the rollers 15 are generally in contact and the charge fed between these rollers is compressed as it enters the furnace, or the charge is It can be modified in such a way that the two rollers 15 can be moved apart so that they can fall freely from the hopper 14 into the furnace chamber 22.

Preferably, at least one of the two rollers is driven, so that the charge in the hopper 14 can be drawn into the furnace chamber 22 by the action of said driven roller.

Between the roller 15 and the furnace chamber 22, there is a furnace inlet 23;
a sealed gate or at least one trap door 17
There is a device for sealing the inlet 23 of the furnace, such as the following.

The trap door 17 consists of two doors, one on each side of the furnace inlet 23, which close together to seal the furnace chamber 22 from the furnace supply 7. Preferably, a second seal is formed.

The rate at which the charge is fed between the rollers 15 and into the furnace chamber 22 can be controlled.

The preset feed rate from conveyor belt 13 is determined based on the charge weight required for proper operation of the furnace.

Additionally, devices are provided for sensing the level of the charge in the hopper 14, such as an upper level detector 39 and a lower level detector 40 mounted on the wall of the hopper 14.

These detectors can issue signals to increase or decrease the feed rate of the conveyor belt 13.

The rate at which conveyor belt 13 feeds the charge into hopper 14 can be varied by varying the density of the charge.

The furnace body 8 has suitable furnace walls 21 made of refractory support materials known in the art.

A furnace chamber 22 is sealed inside the furnace wall 21.

The charge enters the furnace chamber 22 from the feed 7 through the furnace inlet 23 .

The gas generated in the furnace is passed through the furnace wall 21 at the upper part of the furnace chamber 22.
It goes out through the gas vent 20 that penetrates the.

The outlet end 41 preferably tapers downwardly to the outlet 25 and has a conical portion 42 .

Fuel and air inlet devices and steam inlet devices are strategically placed within the conical portion 42 of the discharge end 41 to achieve complete and immediate mixing of air and steam.

Furnace chamber 22 is sealed from the surrounding air.

The steam inlet device and the air inlet device are arranged in a plane perpendicular to the furnace axis and within the discharge end 41 of the furnace on at least one circle centered on the furnace axis.

If the steam inlet device and the air inlet device are arranged on a plurality of circles, it is provided that these circles lie in different planes perpendicular to the axis of the furnace at the discharge end 41 and have different diameters. Make it.

The preferred embodiment has two circles, with 4 to 12 air ports and 4 to 12 steam ports per country.

Steam vents and air vents are arranged alternately in each country,
and are equally spaced.

The air and steam ports are oriented to simultaneously supply air and steam in a direction tangential to the circle.

It has been found that the above-described spacing of the steam and air ports allows uniform, complete and immediate mixing of air and steam within the chargebed. .

2 and 3 show two possible embodiments of arranging the air inlet device and the steam inlet device.

A indicates the air inlet device and B indicates the steam inlet device.

In a preferred embodiment of the invention, the steam inlet devices for introducing steam into the furnace are located in at least one plane perpendicular to the axis of the furnace and preferably equidistant from each other in the conical section 42. Multiple steam ports 44 arranged inside
has.

These steam ports 44 are oriented to supply steam tangentially to the circle formed by the plane and the furnace wall.

In the plane in which the steam ports 44 are arranged, each air inlet device such as an air port 45 is centrally located between two corresponding steam ports 44 .

These air ports 45 are oriented to supply air tangentially to the circle formed by the plane and the oven wall.

If additional air or steam vents are required, they are arranged in two or more planes within the conical portion 42, with at least 4 and no more than 12 steam vents in each plane; An air port corresponding to this can be provided.

The air port 45 may be the same inlet that delivers fuel into the furnace or into the starter burner 46 .

A schematic arrangement of the air port 45 and steam port 44 in this embodiment is shown in FIG.

An alternative embodiment to the embodiment described above is an upright cone 60 made of a metal alloy placed at the bottom of the furnace with its apex toward the furnace inlet and its axis approximately along the furnace axis. It is.

A schematic diagram showing the arrangement of the air and steam inlet devices in this embodiment is shown in FIG.

The air and steam are immediately mixed and discharged along the surface of the upright cone 60 so that they are evenly distributed across the cross section of the furnace.

The steam inlet device for introducing steam into the furnace has a plurality of steam ports arranged on the surface of the cone 60 and equally spaced from each other in at least one plane perpendicular to the axis of the cone.

The steam port is oriented to supply steam tangentially to the circle formed by the plane and the surface of the cone.

The air inlet device for introducing air into the furnace is such that each air inlet has two steam ports on the surface of the cone 60 and in at least one plane perpendicular to the axis of the cone 60 in which the steam ports are arranged. It is preferable to have a plurality of air ports located centrally between the air holes.

The air port is oriented to supply air tangentially to the circle formed by the plane and the surface of the cone.

Of course, as illustrated in FIG. 2 and already explained,
The cone 60 can be used in furnaces with additional steam and air inlet devices located in the conical section 42 of the discharge end 41 of the furnace.

It is important that the air and steam are fed into the lower part of the furnace uniformly with respect to each other and across the cross-section of the furnace perpendicular to the longitudinal axis of the furnace.

The above is preferably accomplished by the air and steam ports shown in FIGS. 1, 2 and 3 and previously described.

The outlet 25 opens into a sealed outlet 9 which has an ash hopper 27 which can be provided with a movable drawer 28 as a bottom.

The ash hopper 27 is connected to the furnace in such a way as to ensure a tight seal and can open into the collection hopper 30 , from which the screw conveyor 31
The ash is removed by a conveying device such as.

The outlet 9 is sealed from the surrounding air.

In the vertical furnace of the invention, the charge is conveyed through the furnace by gravity and the ash is discharged through the outlet 25.

The ash in the ash hopper 27 can be used as a means of supporting the charge layer 47 in the furnace chamber 22.

When the ash is discharged from the outlet 25, it falls into the ash hopper 27 and accumulates on its bottom surface 29.

The height, length and width of the ash hopper 27 are determined by the ash layer (as
k bed) is designed to allow the dormancy angle α of the ash layer necessary to support the charge layer 47 in the furnace.

Said resting angle is defined as the angle between the plane passing through the bottom surface 29 of the ash hopper 27 and the ash layer 48 (see FIG. 1).

Ash continues to be discharged from the furnace chamber 22 until the rest angle α reaches a critical minimum value.

The critical minimum rest angle depends not only on the shape of the ash hopper 27, but also on
It depends on the material in the charge layer and the type of ash.

Taking these factors into account, the critical minimum resting angle is determined empirically.

Therefore, the ash hopper 27 has its dimensions, namely the width W
and length L (not shown) cooperate with height H,
The ash layer 48 is designed to allow the ash layer 48 to have the critical minimum angle of repose necessary to support the layer 47 of the charge of a particular type of material within the furnace chamber 22 .

The bottom of the ash hopper 27 is a draw plate 28 that can be moved by a suitable device such as a hydraulic piston 50.

The puller plate 28 can be pushed in and out to rock under the ash layer 48, causing the ash to move horizontally over the puller plate 28 and into the booklet hopper 30 below. Allow it to fall.

A screen 32 may be disposed between the ash hopper 27 and the collection hopper 30 to remove large pieces or debris of the ash.

The pull plate 28 swings in response to a signal emitted by a device that measures the level of the charge layer 47 in the furnace chamber 22 .

When the level is too high, the pull plate 28 swings so that the ash falls from the ash hopper 27 through the discharge port and into the collection hopper 30.

Ash then falls from the furnace into the ash hopper 27, lowering the level of the charge layer.

When the bell is low enough, the pull plate 28 receives a signal to stop its rocking and the ash continues to fall from the furnace until the critical rest angle is reached.

The entire ash hopper system, the family hopper 27 and the stack hopper 30, can be sealed from the surrounding air.

A screw conveyor 31 removes ash from the collection hopper 30.

The basic method of operating the furnace of the invention is to feed the charge into the charge port 12 by suitable equipment.

When no charge is being fed, the inlet gate 34 can be closed to seal the furnace from ambient air.

The feed passes from the charging port 12 to the hopper 14, where it remains.

If the charge were to bridge above the rollers 15, the charge would not be fed into the furnace chamber 22.

The hopper 14 is provided with a movable wall 35 which can swing the charge and prevent the formation of bridges in the hopper 15 above the rollers 15.

A pair of rollers 1 is provided between the hopper 14 and the furnace chamber 22.
5 and an inlet 23 of the furnace.

The rollers 15 rotate in opposite directions, one roller in the same direction as the hour hand and one roller in the opposite direction.

Therefore, at the engagement portion of the rollers 15, the outer periphery of the rollers 15 moves from the direction of the hopper 14 to the direction of the furnace chamber 22.

Preferably, at least one of the rollers 15 is driven.

Driven rollers 15 pull the charge from hopper 14 and send it through furnace inlet 23 towards furnace chamber 22 .

The feed rate of the charge into the furnace is predetermined by the composition of the charge and the operating conditions of the furnace.

The level of the charge in the charging hopper 14 is determined by the level detector 3.
9 and 40 continuously.

This level detector increases the speed of roller 15 depending on whether more or less charge is required to maintain the desired level. A signal is sent to the roller 15 to either slow down or slow down.

When the level is too high, the speed of the roller 15 increases; when the level is too low, the speed of the roller decreases.

The spacing between the two rollers 15 can vary depending on the type of charge, the degree of compaction of the charge desired by the rollers 15 and the desired feed rate.

As the charge is pulled from the hopper 14 between the rollers 15 towards the furnace chamber 22, the two rollers 15
The degree of compaction of the charge can be varied by how close the two are placed together.

Furnace chamber 2 by compressing the charge passing through rollers
An additional seal is provided between 2 and the surrounding air.

The charge can be compacted to a desired density, which can be determined by the spacing of the two rollers 15 and the density of the charge being fed into the charge port 12.

In this way, the charge is fed into the furnace chamber 22 and the furnace is sealed from the surrounding air.

There is a furnace inlet 23 between the roller 15 and the furnace chamber 22,
The inlet 23 of this furnace has a sliding gate or at least one
It preferably has a suitable sealing device such as two trap doors 17.

During operation, trap door 17 is generally left open.

If the furnace does not require a charge, trap door 1
7 can be closed to prevent the rollers from being heated by the radiant heat of the mass in the furnace and to prevent loss of the seal between the furnace and the surrounding air.

The charge is passed into the furnace chamber 22 and remains there forming a layer 47 of charge.

The charge layer 47 extends from the point where the charge is taken from the feed 7 to the outlet 25 of the furnace chamber 22 .

In the illustrated embodiment of the invention, the furnace has at least two zones: a volatilization zone 53 and a carbonization reaction zone (cha
reaction zone ) 54 is present in the layer 47 of the charge.

The volatilization zone 53 is an area where light hydrocarbon volatilization occurs.

Volatilization zone 53 is adjacent to carbonization reaction zone 54 and is between it and charge port 12 .

The carbonization reaction zone 54 is a zone in which a chemical reaction is caused to the charge.

Carbonization reaction zone 54 is adjacent to volatilization zone 53 and is between this zone and outlet 25 .

Having these two zones inside the same gasifier uses two processes that may be considered incompatible, but allows for careful control of the air and steam introduced into the conical section 42 of the furnace. By doing so, the two zones can exist simultaneously under desired conditions.

Light hydrocarbons are pyrolyzed from the volatile zone and degassed 20
Exit the furnace through.

The volatilization zone 53 contains highly flammable gases which, when combined with a sufficient amount of oxygen at suitable humidity, result in combustion or the possibility of an explosion.

There should not be more than about 5% oxygen present in the volatilization zone 53.

Adjacent to said zone 53 is a carbonization reaction zone 54 in which steam and air are present.

The amount of steam and air within the carbonization reaction zone 54 must be carefully controlled to control the endothermic and exothermic reactions that occur within this zone.

Heat is released as a result of the exothermic combustion reaction between the oxygen and the waste, while heat is dissipated as a result of the endothermic reaction of the water gas.

The amount of oxygen fed into the carbonization reaction zone is adjusted to control combustion and to ensure that only a controlled amount of oxygen is allowed to enter said zone, or to ensure that only a controlled amount of oxygen is allowed to enter said zone. must be controlled to ensure that no

The hydrogen and carbon monoxide produced in the water gas reaction leave the furnace with the flue gas.

Most of them do not oxidize because the amount of air in the carbonization reaction zone is controlled.

During operation, a zone may be formed between the charging port 12 and the volatilization zone 53.

This zone is a drying zone 55 where water evaporates from the charge layer.

The water leaves the furnace through the vent 20 along with gases created by combustion and volatilization occurring inside the furnace chamber 22.

Finally, adjacent to the carbonization reaction zone 54 and between this zone 54 and the outlet 25 there is an ash zone 56 .

Steam and air are supplied into the ash area 56 by suitable steam and air inlet devices.

The steam port 44, like the air port 45, connects to the carbonization reaction zone 54.
It is formed inside the ash area 56 near the ash area 56.

As the air rises through the ash area 56, it cools the ash as it moves progressively towards the outlet 25.

The air itself is heated by the hot ash as it rises through the ash zone 56 in a direction opposite the ash flow.

The weight of a charge of known heat value is measured as it enters the furnace.

By knowing the calorific value of the waste in pounds of BTU and the number of pounds of waste per hour, the calorific value per unit time and BTU per hour during the reaction of the waste can be determined.

The amount of air required to react the portion of fixed carbon in a given charge in the carbonization reaction zone can also be determined and preset.

water gas shift reaction
steam is added as a means of cooling the carbonization reaction zone which is reacted to generate carbon oxide and hydrogen.

The water gas shift reaction is endothermic, so the addition of steam helps moderate the temperature of the carbonization reaction zone.

Additionally, the ash moving downward through the carbonization reaction zone carries away sensible heat.

Different charges produce different amounts and compositions of ashes, and these ashes carry away different amounts of heat.

The amount of steam therefore depends on the composition of the charge and the cooling power of the steam.

The air to steam ratio is then determined by knowing the carbon to ash ratio and can also be preset.

The amount of air required to gasify a fixed amount of charge with a known calorific value is determined and a signal is sent to a controller that sends a measured flow rate of steam to maintain the desired air-to-steam ratio. It will be done.

The humidity in the carbonization reaction zone 54 is continuously measured.

This temperature can be varied depending on the nature of the waste being charged.

Once the change in temperature is measured, the introduction of more or less air or steam is controlled accordingly.

The temperature of the carbonization reaction zone should also be monitored to keep it below the temperature at which the ash melts to avoid melting or clinkerization of the ash material passing through this zone.

For example, in the case of waste paper, reaction temperatures can be allowed to reach approximately 1093° C. (below 2000° C.) without adverse effects regarding clinkering and/or slagging.

However, when dried municipal sludge is used, the reaction temperature is around 871°C to avoid slagging due to the low melting point salts present in the ash.
(1600'F) or below.

An example of a preferred method of operation of the present invention is the operation of a continuous gasifier in which there are four zones.

In this example, the amount of heat of the waste material charged is 4111 ~
4166Kcal/, p(7400~7500BTU
/ pound).

The temperature at the top of drying zone 55 is maintained at approximately 413°C (below 775°C).

The humidity at the top of the volatilization zone 53 is approximately 538°C (below 1000°C)
It is.

The temperature at the top of the carbonization reaction zone 54 is approximately 1093°C (200°C).
0 below).

The temperature at the top of the ash zone 56 is maintained at approximately 600"F.

The temperature of the ash at outlet 25 is approximately 204°C (400”F).
) will be maintained.

The air to steam ratio is approximately 13.5.

The ash is discharged from the furnace chamber 22 through the outlet 25 into the ash hopper 27 and deposited on the draw plate 28.

The ash collects in the ash hopper 27 until the angle of rest α of the ash in the ash hopper reaches a critical minimum angle of rest.

When the angle of rest of the ash reaches the critical minimum angle of rest, the ash is no longer discharged and the layer of charge is supported on the draw plate 28 by the ash itself.

At least one level detector 51 is mounted on the furnace wall 21 inside the furnace chamber 22 .

When the level of the charge layer is higher than the specified level, the pull plate 28 is signaled to advance or retract in an oscillating manner.

The ash passes from the drawer plate 28 through the discharge port 25 to the collection hopper 3.
0, the rest angle increases and more ash falls from the discharge port 25 into the ash hopper 2T.

When the level of the layer of the charge falls below a certain level, the pulling plate 28 stops its rocking movement and the ash falls until the minimum angle of rest α is obtained, and the ash in the ash hopper 27 is removed from the charge. layer 4
It acts to stop and support 7 so that it does not move.

Ash is discharged from the ash hopper 27 through the discharge port by pulling the draw plate 28.

The debris is transferred from the ash to the screen 3 to the collection hopper 30.
It can be sieved by 2.

The furnace of the present invention can be operated such that the amount of particles emitted from the vent 20 is minimized.

This is accomplished by controlling the flow rate of gas through the charge layer 47.

Only a sufficient amount of combustion air is required to react with the fixed carbon portion of the waste.

By having a low flow rate, particle entrapment by the gas flow is minimized.

Under optimal operating conditions, very few particles will be emitted.

[Brief explanation of drawings]

1 is a cross-sectional view of the furnace of the present invention; FIG. 2 is a schematic diagram of the discharge end of the furnace showing the air and steam inlet devices; and FIG. FIG. 2 is a schematic diagram illustrating the arrangement of steam inlets. In the figure, 7 is the "supply section"; 8 is the "main body section"; 9
12 is the ``charging port''; 13 is the ``conveyor/
14 is the "charging hopper"; 15 is the "roller"; 17 is the "trap door"; 20 is the "gas vent 1"; 21 is the "furnace wall"; 22 is the "furnace chamber"; 23 is the "
Furnace inlet”; 25 is “discharge port”; 27 is “ash hopper”
; 28 is the "drawing board"; 30 is the "collection hopper"; 3
2 is the “screen”; 44 is the “steam port”; 45 is the “air port”; 47 is the “charge layer”; 48 is the “ash layer”
; 53 is "volatile zone"; 54 is "reaction zone"; 55
56 is the "ash area"; 50 is the "hydraulic piston"; 51 is the "level detector".

Claims (1)

Claims: 1. Continuously operated combustion chamber having a vertically oriented combustion chamber with a furnace inlet at the upper end and an ash outlet at the lower end, and a device for collecting and discharging ash from said ash outlet. In a vertical gasifier, the device for collecting and discharging ash has an ash hopper disposed below the ash outlet, and the ash hopper is slidably mounted therein. A flat plate forming the bottom of the ash hopper is provided, and ash falling from the ash outlet is collected on the flat plate,
the flat plate is positioned such that a deposit of ash forming an angle of rest thereon and accumulating serves to seal the ash outlet and support the material charged into the combustion chamber; and further comprising a device for periodically reciprocating the plate to cause ash to be discharged from the hopper. 2. The furnace according to claim 1, further comprising: a device for detecting the level of the layer of charge in the combustion chamber and generating a signal in response thereto; 2. A furnace according to claim 1, characterized in that a device is provided for moving said plate so as to discharge ash from said ash hopper. 3. A method of operating a continuously operating vertical gasifier, comprising forming in the furnace a layer of a charge of material to be combusted and feeding the charge to the top of the layer. ash exiting from the bottom of the bed in a method comprising: allowing the charge to pass downwardly through the bed; and removing ash from the bottom of the bed through an outlet. , collecting in an ash hopper located in the lower part of the furnace below the outlet and having a substantially horizontal bottom plate, the collected ash forming a pile having a critical rest angle on the bottom plate; allowing the collected ash to accumulate on the bottom plate until the collected ash pile reaches the outlet in the lower part of the furnace and seals the outlet; and of sufficient dimensions to thereby cause the ash pile to support the layer of charge in the furnace and to seal the outlet and maintain support for the layer of charge. A method characterized in that ash is periodically or continuously removed from the ash hopper at a rate such that the ash buildup is maintained at a rate that maintains the ash build-up. 4. The method of claim 3, wherein the level of the charge layer in the furnace is monitored and the ash is removed from the ash at a rate sufficient to maintain this level substantially constant. A method characterized by discharging from a hopper. 5. The method according to claim 3 or 4, wherein the ash is removed by reciprocating the bottom plate so as to transport the ash laterally from the ash hopper and discharge the ash into the collection hopper. from said ash hopper.