JPH0647226A - Dust removing device for high temperature gas - Google Patents

Abstract

PURPOSE:To provide a dust removing device for high temp. gas capable of preventing abnormal deposition of dust on a ceramic filter even when a large quantity of dust arrives and being free from the damage of ceramic filter caused by thermal even when used for the removal of dust in a gas containing an unburned portion such as soot. CONSTITUTION:A defuser 8 is provided near a gas introducing opening 10, a gas passage 13 is provided between a defuser inlet part 19 and a hopper part 13 and the dust containing gas is refluxed from the hopper part 7 to a gas inlet chamber 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power plant using a pressurized fluidized bed boiler, a direct coal combustion apparatus (Coal Di).
The present invention relates to a high temperature gas dust remover in which a filter made of porous ceramics suitable for dust removal of a high temperature dust-containing gas discharged in a combustion process such as rect firing) or a coal gasification plant is incorporated.

[0002]

2. Description of the Related Art The technology relating to a high temperature gas dust remover incorporating a ceramic filter is considered to be a next-generation highly efficient and clean (emission exhaust gas is low NO _x , low SO _x ) coal utilization technology. It is considered to be a key technology for realizing a coal gasification plant and a power plant using a pressurized fluidized bed boiler, which are currently being worked hard in various countries around the world.

When the dust remover is used by incorporating it into these plants, the behavior of dust at high temperatures is of particular concern. That is, since the viscosity coefficient of gas generally increases as the temperature rises, dust is strongly affected by the flow of gas at high temperatures, and the main dust content in the dust removal chamber (the part where solid-gas separation is performed in the dust removal device). Even if the gas flow is configured to be generally downward, a part of fine dust tends to flow against the gravity along with the disturbed gas flow and does not easily fall to the hopper.

In an actual plant, the flow in the dust removing chamber is constantly changing due to the turbulence caused by the operating conditions of the dust removing apparatus itself or the disturbance in the upstream system or the downstream system, and the turbulent flow accompanied by various sidestreams removes dust. It exists inside the device.

As a result, the following problematic phenomena occur in the dust removing device. a. Dust bridging: A phenomenon seen in so-called candle type dust removers that use tubular ceramic filters with one end closed, and cross flow type dust removers that use plate-shaped ceramic filters. Due to the presence of the sidestream of the dust, the dust does not drop into the lower hopper even when backwashing the ceramic filter, and it adheres to the nearby ceramic filter again, and while this is repeated, the dust is steadily on the surface of the ceramic filter. It is a phenomenon in which a part of the passage on the dust-containing gas side of the ceramic filter is finally blocked by the accumulated dust, or a part of the filtering surface of the ceramic filter is covered with a thick dust accumulation layer.

[0006] Therefore, when bridging of dust occurs, the effective filtration area of the filter gradually decreases and the treatment capacity of the dust remover decreases, but when removing the combustion gas from the pressurized fluidized bed boiler, The unburned components contained in the bridged dust often ignite and burn, causing fatal damage (cracks or damage) such as damage to the ceramic filter in the dust remover due to thermal stress.

Further, in the dust removal treatment of synthesis gas in a coal gasification plant, when the state replaced with non-oxidizing gas immediately after the operation is stopped is changed to air or when the operation is restarted, the oxidizing atmosphere containing oxygen is changed. When the gas is present in the dust remover, the unburned components in the bridging dust ignite and cause fatal thermal stress damage to the ceramic filter of the dust remover.

B. When the load on the plant fluctuates, a large amount of unburned components including soot are discharged into the combustion gas and are deposited on the surface of the ceramic filter, and then ignite and abnormally burn. For example, when removing the combustion gas from a pressurized fluidized bed boiler, when trying to increase the boiler load from a low load state, a large amount of unburned components are generated despite the high oxygen concentration, and a large amount of dust is contained in the dust. Combustion gases containing soot (sometimes up to 30%) and more than 1000 ppm carbon monoxide may be evolved.

In a pressurized fluidized bed boiler, a method for introducing combustion gas, which is roughly dust-removed by a cyclone, into a dust-removing device having a built-in ceramic filter is generally aimed, but in the cyclone, the dust concentration in the dust-containing gas rapidly increases. In such a transient state, dust overflows and the dust removal function is not sufficiently exerted.

Therefore, the dust containing a large amount of unburned components passing through the cyclone reaches the ceramic filter of the dust remover. At this time, since the dust concentration in the dust-containing gas increases 5 to 10 times the dust concentration in the steady state, the increase gradient of the filtration differential pressure also increases to 5 to 10 times the steady state.

In the candle type dust removing device, since the flow passage cross-sectional area on the dust-containing gas side of the dust removing chamber is large, it is difficult to make the flow of the dust-containing gas a complete downward flow, and the dust is partially absorbed in the tubular ceramic filter. There is a tendency for a large amount to adhere, and there is a high risk of ignition if the dust contains a large amount of unburned components.

A tubular filter is incorporated as a ceramic filter, and the inside of the container is partitioned by a plurality of horizontal tube plates,
A plurality of tubular ceramic filters are held by a tube plate at their ends, and a dust removal device configured to allow dust-containing gas to pass through the inside of the tubular ceramic filters and flow downward (Japanese Patent Publication No. 63-40567). 2-22689, Japanese Patent Publication No. 3-24251, Japanese Patent Publication No. 3-61076, and Japanese Patent Laid-Open No. 1-310.
03397, etc., describes this type of dust remover. In the following, referred to as a tube type dust remover), the flow path cross-sectional area on the dust-containing gas side is small, and the flow on the dust-containing gas side is almost complete downward flow. Has been done.

Therefore, under normal operating conditions, dust does not deposit thickly on the filtration surface of the tubular ceramic filter, the absolute amount of the unburned components that fly in does not fluctuate significantly, and the amount of dust is always less than about 10% in dust. Contains unburned components,
As long as it burns constantly and gradually, there is no problem of damaging the tubular ceramic filter.

However, even in the case of the tube type dust remover, when a dust-containing gas containing a large amount of unburned components is introduced in a short time, the dust is discharged on the inner surface of the lower end of the tubular ceramic filter where the downward gas flow velocity is close to zero. A large amount of dust will be accumulated, and this dust will ignite and burn all at once, causing the temperature inside the tubular ceramic filter to rise rapidly, and the temperature difference with the outside of the tubular ceramic filter will exceed the allowable temperature difference of the ceramic material. A phenomenon occurs in which the ceramic filter is damaged by thermal stress.

That is, at the lower end of the tubular ceramic filter, the distribution of the pressure and velocity in the gas inlet chamber of the container affects the tubular ceramic filters, and the flow rate of the dust-containing gas varies among the tubular ceramic filters, resulting in a tubular ceramic having a flow velocity of almost zero. It has become clear that some filters exist, and some tubular ceramic filters allow gas to flow back from within the hopper.

Furthermore, the distribution of pressure and velocity in the gas inlet chamber is affected by fluctuations in the upstream of the plant regardless of whether it is a tube type dust remover or a candle type dust remover, and changes momentarily, which disturbs the dust remover chamber and the hopper. It has also become clear that it is one of the causes of gas flow.

In the tube type dust remover, Japanese Patent Publication No.
In 24251, a dust removal method of extracting dust-containing gas from the hopper and returning it to the upstream side has been proposed for the purpose of reducing the filtration differential pressure and reducing the backwash frequency.

This proposal is a useful method which can solve the above-mentioned problems in both the tube type dust removing device and the candle type dust removing device. A large amount of dust-containing gas is emitted, and a corresponding power is required to recirculate the gas upstream.

In order to transfer a gas having a high dust concentration, it is most practical to use an ejector driven by steam or high pressure air. However, the efficiency of the ejector using compressed air is at most 4%, and it is not realistic to secure the gas recirculation amount recommended by the above proposal with a dust remover with a large amount of treated gas.

Particularly, in the case of the candle type dust remover, since the flow passage cross-sectional area of the dust-containing gas in the dust removing chamber is large and the required gas recirculation amount is larger than that of the tube type dust remover,
Usage of utilities such as compressed air has a great impact on plant efficiency.

In order to obtain the same effect as the reflux, it is also effective to extract a part of the dust-containing gas together with the dust and take it out to the external system, but since the extraction of a large amount of dust-containing gas affects the efficiency of the plant, In the power generation plant, the amount of dust-containing gas extracted is suppressed to 1 to 2%. Therefore, this method cannot obtain a sufficient recirculation effect, and if a large amount of dust containing unburned components such as soot flies during a load change or the like, it is inevitable that a large amount of dust will be deposited on the surface of the ceramic filter.

[0022]

In view of the above-mentioned problems of the prior art, an object of the present invention is to remove dust from exhaust gas from a high temperature pressurized combustion process such as a pressurized fluidized bed boiler or a coal gasification plant. An object of the present invention is to provide a dust removal device for high temperature gas, which is suitable for treatment and has a practical means capable of extracting the dust-containing gas from the hopper portion and returning it to the dust-containing gas introduction portion with a small amount of energy consumption. is there.

[0023]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and a high temperature gas dust removing apparatus of the present invention has a ceramic filter built in a container and is captured by the ceramic filter. The dust removing device is equipped with a backwashing means for reclaiming the dust and regenerating the ceramic filter, and the lower part of the container serves as a hopper for collecting the removed dust. A diffuser is attached to the dust gas introduction pipe, and a gas passage that connects the inlet of the diffuser (sue-wide cylinder) that has a relatively low static pressure and the hopper is provided. Part of the dust-containing gas in the hopper is the gas passage. It is characterized in that it is recirculated to the dust-containing gas introduction portion of the container via the diffuser and.

The gas flow velocity in the pipe for introducing the dust-containing gas into the dust remover is set to a large value within the range where erosion does not occur in order to avoid adhesion and accumulation of dust in the pipe, and in the dust remover of the present invention, , Most of the dynamic pressure of the introduced gas is converted to static pressure by the diffuser to increase the pressure in the dust removal chamber, and the resulting differential pressure causes the dust-containing gas to flow from the hopper through the gas passage to the upstream side of the dust removal device. Means are provided for refluxing.

More specifically, the diffuser is provided in the vicinity of the gas introduction port of the container, and the gas passage communicating with the hopper is provided in the low static pressure portion of the inlet of the diffuser. As long as such a recirculation means is provided, the design of the dust-containing gas introduction pipe, the model of the dust removing device, the type of plant to be applied, and the variation in the operating conditions of the plant upstream and downstream, which can cope with fluctuations in the hopper, It is possible to secure the flow rate of the dust-containing gas to the dust-containing gas introduction portion.

Here, the diffuser includes a diffuser that exerts a function of a diffuser hydrodynamically, that is, a pressure recovery function, and does not mean only a divergent diffusion tube.
For example, a large R (R) may be provided at the gas introduction port to the container, or an orifice may be provided at the gas introduction port to the container so that the pressure is low immediately downstream of the orifice and the gas flow spreads downstream thereof It may be configured to restore pressure.

In the high-temperature dust-containing gas dust remover of the present invention, when the dust remover is a tube-type dust remover, the recirculation rate of the dust-containing gas from the hopper to the dust-containing gas inlet is introduced into the dust remover. It is preferably 3 to 15% of the dust-containing gas. Further, when the dust removing device is a candle type dust removing device, it is preferable that the reflux rate of the dust-containing gas is also 5 to 25%.

If the flow rate of the dust-containing gas is less than 3% (6% in the candle-type dust remover), the effect of preventing abnormal accumulation of dust on the partial surface of the filter tube is small.
If it is more than 0%, dust is likely to be rolled up from the hopper portion, and energy consumed is increased.

In the preferred high temperature gas dust remover of the present invention, the ceramic filter is a tubular ceramic filter, the interior of the container is partitioned by a plurality of horizontal tube plates, and a gas inlet chamber is provided above the uppermost tube plate. A plurality of tubular ceramic filters are respectively held by the tube sheet at their ends, and the dust-containing gas is configured to flow inside the tubular ceramic filter.

In the tube type dust remover, since the flow path of the dust-containing gas in the dust removing chamber is provided inside the filter tube, the cross-sectional area of the flow path of the dust-containing gas is small, and the dust-containing gas of a relatively small amount is contained. Even if a dust-containing gas containing a large amount of dust is introduced into the dust remover by recirculating the gas from the hopper to the gas inlet chamber, a large amount of dust is accumulated on the filtration surface or the dust-containing gas flow path due to the dust The clogging of the filter tube can be prevented, and even if a large amount of dust containing the unburned component is introduced into the dust remover, the problem that the unburned component is ignited near the surface of the filter tube and the filter tube is thermally damaged is avoided. You can

In another preferred high temperature gas dust remover of the present invention, the ceramic filter is a tubular ceramic filter with one end closed, and a plurality of tubular ceramic filters are attached vertically below or above the clean gas header in a substantially vertical manner. The unit is disposed in the container, and the dust-containing gas is configured to be sequentially lowered from the upper portion of the dust removing unit to remove the dust.

When the high temperature gas dust remover is a candle type dust remover in which such a dust remover is provided in the container, the cross sectional area of the dust containing gas in the dust remover is large,
It is necessary to recirculate a considerable amount of dust-containing gas from the hopper to the dust-containing gas inlet.

In the dust remover for high temperature gas of the present invention, the dust-containing gas having a low static pressure sent at a high flow rate is caused to flow through the diffuser to convert the dynamic pressure into static pressure, thereby increasing the pressure in the container of the dust remover. A suction port is provided at a low static pressure portion of the diffuser inlet, and the dust-containing gas in the hopper is sucked through the gas passage, and the dust-containing gas is returned to the dust-containing gas introduction portion of the dust remover. Therefore, it is possible to recirculate a sufficient amount of dust-containing gas without particularly exhausting the utility such as compressed air.

In another preferred high temperature gas dust removing apparatus of the present invention, a plurality of dust removing units are arranged vertically and / or horizontally in the container. A large Tiered dust removal unit with multiple layers arranged in a container
In the case of the candle type dust remover of the type, there are several places where the gas flow stagnates in the dust-containing gas space, but in the dust remover of the present invention, it is sufficient to provide a plurality of suction ports. It is possible to recirculate a large amount of dust-containing gas from the hopper to the dust-containing gas introduction portion, thus forming a large-scale practical dust remover that does not tend to accumulate a large amount of dust on a part of the filtration surface of the filter tube. be able to.

In another preferred high-temperature gas dust remover of the present invention, a throttle pipe or an ejector nozzle is attached on the upstream side of the diffuser inlet, and an ejector is arranged at the diffuser inlet. That is, the ejector is one in which a throttle pipe or an ejector nozzle is combined on the upstream side of the inlet part of the diffuser, and an intake port is provided at the inlet part of the diffuser, and the diffuser is included as a part of the ejector. Even if the dynamic pressure of the dust gas is small, it is possible to secure a sufficient suction capability of the dust-containing gas from the gas passage.

Generally, although the flow velocity in the dust-containing gas introduction pipe to the dust remover is set to be relatively high, a diffuser is provided at the dust-containing gas introduction part of the dust remover for the purpose of recovering static pressure in the related art. The examples given are not known.
Therefore, compared with the conventional design without the diffuser, even if the ejector structure is provided with the throttle pipe on the upstream side of the diffuser, the increase in the pressure loss in the dust removing device is suppressed to the extent equivalent to the pipe resistance required for gas recirculation at the most. be able to.

In another preferred high temperature gas dust remover of the present invention, the container is a pressure container, and the gas passage is provided inside the pressure container.

Since the gas passage for returning the dust-containing gas from the hopper to the dust-containing gas introduction portion of the dust removing device can be shortened by being provided inside the pressure vessel, it is necessary for the circulation of the dust-containing gas. It is possible to reduce the driving force to be used, and there is no need to provide a passage outside the container, so there is no need to install a heat insulating material outside the passage. Since it is not necessary to add the device, the cost required for constructing the device can be reduced.

The high temperature gas dust remover of the present invention is a pressurized fluidized bed boiler which is a future energy technology which uses coal and has high efficiency and is clean (a small amount of SO _x and NO _x is discharged.). Is particularly suitable for a power plant in which In this type of power plant, it is possible to obtain high power generation efficiency by using a steam turbine with steam of a boiler and a gas turbine driven by combustion gas together, and the dust remover is in a pressurized state. It is used for the purpose of removing dust in the combustion gas that is harmful when the gas is used to drive the gas turbine (wears the gas turbine and shortens its life).

The high-temperature gas dust remover of the present invention can be used for removing dust of high-temperature dust-containing gas containing a large amount of unburned components which is temporarily generated when the boiler load is increased.
By preventing a large amount of dust containing a large amount of unburned components from accumulating on the filtration surface of the ceramic filter, the unburned components in the deposited dust are less likely to ignite, and are incorporated even if they ignite and burn. It is possible to avoid catastrophic thermal stress damage to the ceramic filter.

[0041]

EXAMPLES Examples of the high temperature gas dust removing apparatus of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these examples.

FIG. 1 is a vertical sectional view showing an embodiment in which the high temperature gas dust remover according to the present invention is applied to a tube type dust remover. In FIG. 1, 1 is a tube type dust remover, 2 is a pressure vessel, 3 is a tubular ceramic filter (filter tube), 5a, 5b, 5c and 5d support each filter tube and the inside of the pressure vessel is horizontal. A tube plate (5a and 5d partition between the dust-containing gas space and the clean gas chamber, and another tube plate partitions between the clean gas chambers), and 6 is a filter tube for the inflowing gas. Is a hopper portion, 8 is a diffuser, 9a, 9b and 9c are upper, middle and lower clean gas chambers, and 10 is a gas inlet. A heat insulating material is lined inside the pressure vessel 2, but this is omitted in FIG. 1.

Further, 11a, 11b and 11c are clean gas outlet pipes which also serve as diffusers of ejectors for injecting backwash gas into the upper, middle and lower clean gas chambers respectively, 12 is a clean gas outlet and 13 is a hopper. Gas passages made of a heat-resistant metal tube through which the dust-containing gas emitted passes, 14a, 14
b and 14c are ejector nozzles for ejecting backwashing compressed air to the respective clean gas outlet pipes, 15 is a skirt provided at the lower end of the filter pipe 3, and 16 is a suction passage in which the gas passage 13 is open to the hopper. A port, 17 is an ejector having the diffuser 8 as a part thereof, and 18 is an ejector nozzle attached to the gas introduction port 10.

Here, the heat-resistant metal pipe of the gas passage 13 also serves as a support for supporting the diffuser 8, 19 is an inlet portion of the diffuser 8, and 20 is an inlet for sucking dust-containing gas from the hopper portion 7 through the gas passage 16. Is. This gas passage 1
Of the three, the portion passing through the clean gas chamber may be used as a filter tube and the filter tube may be used as a gas passage.

In the dust remover of FIG. 1, the ejector nozzle 18 attached to the gas inlet 10 is separated in the middle so as to absorb the deviation due to the thermal expansion of the heat-resistant metal tube forming the gas passage 13, and the fitting structure. It is said that. Also,
The dust-containing gas flows in from the gas inlet 10 in the direction of the arrow, and is ejected by the ejector nozzle 18 into the inlet portion 19 of the diffuser 8.
To form a low static pressure, suck the dust-containing gas in the gas passage 13 from the suction port 20 provided at the inlet 19 of the diffuser with the smallest diameter, and gradually recover the static pressure in the diffuser 8. Then, the gas flows into the gas inlet chamber 6 at a static pressure that is, for example, 1000 mmAq higher than the static pressure of the inlet portion 19 of the diffuser.

In the gas inlet chamber 6, inevitably a maximum of 70 m
Since there is a static pressure distribution having a difference of about mAq, there is some variation in the flow velocity of the gas flowing into each filter tube 3. In addition, since the static pressure and flow rate of the dust-containing gas flowing into the gas inlet 10 fluctuate from moment to moment, the static pressure and velocity vector in the gas inlet chamber 6 also change accordingly, and each filter tube The flow rate of the gas flowing into 3 also changes.

The dust-containing gas distributed to each filter tube 3 is
While descending inside the filter tube 3, it is filtered by the inner surface of the filter tube 3 to become clean gas, and the clean gas chambers 9a, 9
It flows into b and 9c. The gases exiting the clean gas chambers 9a, 9b, 9c are clean gas outlet pipes 11a, 11b, 11 respectively.
After passing through c, they are collected and sent from the clean gas outlet 12 to the downstream system.

The dust-containing gas flowing in the filter tube 3 is exuded outward while flowing in the filter tube 3, so that the descending speed is gradually decreased downward, and the filter tubes are different at different speeds. It flows into the hopper part 7 from the lower side of the skirt 15 attached to the lower part.

If the static pressure distribution in the gas inlet chamber 6 is uniform and the ventilation pressure loss of the filter tube is almost uniform, the dust-containing gas should flow into the hopper portion 7 from the lower end of each skirt 15 at substantially the same speed. Yes, but in reality this is not the case. The skirt 15 is provided so that dust falling from the lower end of the filter tube 3 can be directly used as the suction port 1 of the gas passage 13.
In order to prevent the dust from accumulating on the bottom of the hopper portion 7, it is preferable that the dust accumulated on the bottom of the hopper portion 7 be lengthened.

Considering gas pulsation in the hopper 7, the distance from the tip of the skirt 15 to the suction port 16 of the gas passage 13 is preferably 100 mm or more, more preferably 200 mm or more. The sucked dust-containing gas passes through the gas passage 13 and the suction port 20 to the diffuser 8
Is sucked in and is recirculated to the gas inlet chamber 6.

When a static pressure difference of 300 to 1000 mmAq is provided between the outlet and the inlet of the diffuser 8, the dust-containing gas introduced into the dust remover varies depending on the design of the tube type dust remover, the type of the applied plant, etc. About 7 to 15%
It becomes possible to recirculate, and it is possible to secure the descending speed of the dust-containing gas at the lower end portions of all the filter tubes.

When the dust-containing gas is introduced into the dust remover and dust accumulates on the inner surface of the filter tube 3, the gas inlet chamber 6
The filtration differential pressure between the clean gas outlet pipes 11a, 11b, and 11c begins to gradually increase. The filtration differential pressure is normally maintained within a predetermined low differential pressure range by performing backwashing at regular intervals.

For backwashing the filter tube, compressed air is ejected by opening and closing a control valve that operates at high speed.
4a, 14b, and 14c are sequentially ejected, the pressure in the corresponding clean gas chambers 9a, 9b, 9c is made higher than the pressure on the dust-containing gas side, and the gas is made to flow backward from the outside of the filter pipe 3 to the inside thereof. It is carried out sequentially by removing the dust accumulated in the.

Opening time of these control valves (fully closed to fully open,
The time required for full closing) is usually 0.1 to 0.5 seconds.
What is particularly important for effective backwashing is the time required from full close to full open and the holding time in the fully open state.If the time required from full close to full open is too long, the pressure outside the filter tube and the pressure inside the filter tube are increased. Difference (hereinafter referred to as backwash differential pressure) cannot be made sufficiently large, and if the holding time in the fully opened state is too short, the rise of backwash differential pressure will be insufficient and regeneration of the filtering function of the dust remover will be incomplete. Becomes

If regeneration by backwashing is incomplete, the dust removal capacity becomes unstable as the filtration differential pressure gradually increases.
Backwash conditions are control valve type, size, compressed air pressure,
There is an optimum valve opening time depending on the thickness of the compressed air pipe, the effective filtration surface area of the filter pipe for backwashing, the dead volume outside the filter pipe (volume of the clean gas chamber), and the like.

Backwash is performed at regular time intervals (for example, every 15 minutes)
The cleaning gas chambers of 9a, 9b, and 9c may be intermittently carried out at intervals of 60 seconds or less.
The clean gas chambers 9b and 9c may be backwashed at regular time intervals (for example, 5 minutes).

FIG. 2 is a vertical cross-sectional view showing an example in which the high temperature gas dust remover of the present invention is applied to a so-called Tiered type candle dust remover. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. 2 is taken as a sectional view taken along the line BB of FIG.

In FIG. 2, 31 is a candle type dust remover, 32 is a gas inlet, 33 is a clean gas outlet, 34 is a pressure vessel, 35 is a heat insulating material attached inside the pressure vessel 34, and 36 is one end closed. Filter pipe, 37 is a clean gas header, 38 is a backwashing ejector (not shown) inside, and a plurality of filter pipes 36 are attached to the lower side of the clean gas header 37 in a substantially vertical direction.
9 is provided inside the pressure vessel 34 and includes a dust removing unit 38.
It is a tube plate that suspends and separates the dust-containing gas space and the clean gas space 51.

Further, 40 is an ejector nozzle for backwashing inserted in each dust removing unit, 41 is a gas inlet 32.
A guide cylinder for directing the flow direction of the dust-containing gas flowing downward from the filter pipe 36, 42 is a hopper portion, 43 is a gas passage, 44 is a diffuser, and 45 is a gas passage opened to the hopper portion 42. 43 is a suction port, 46 is a diffuser inlet part, 47 is a throttle pipe provided on the upstream side of the diffuser inlet part 46, and 48 is a suction port opened to the diffuser inlet part 46 for sucking dust-containing gas from the gas passage 43. , 50 are dust removing chambers surrounded by the guide cylinder 41.

In FIG. 2, the dust-containing gas is introduced into the gas inlet 32.
Further, it flows into the dust removing device 31, is diverted from the upward flow to the downward flow by the guide cylinder 41 as shown by the arrow, flows into the upper part of the upper dust removing unit, and enters the dust removing chamber 50. Here, the dust-containing gas is the filter tubes 36 of the upper two sets of dust removal units.
And flows down to reach the hopper section 42. Part of the dust-containing gas is returned from the suction port 45 to the diffuser inlet 46 via the gas passage 43, and is sent to the upper part of the dust removing chamber 50 together with the dust-containing gas introduced into the dust removing device.

By circulating the dust-containing gas in this manner, the dust removing unit 3 in the dust removing chamber 50 is used in this dust removing apparatus.
The gas flow in the horizontal direction between 8 is suppressed, and the gas flow that descends is ensured even at the lower end of the filter tube of the dust removal unit at the lowermost stage where the gas descending speed is minimum in the dust-containing gas side space.

On the other hand, the clean gas filtered by the filter tube 36 rises in the filter tube 36, enters the clean gas header 37, is collected in the clean gas space 51, and is discharged into the clean gas outlet 33.
Sent to the downstream system.

For backwashing, air is ejected from the ejector nozzle 40 for each dust removal unit 38 in order to increase the gas pressure in the clean gas header 37 higher than the pressure on the dust-containing gas side, and the gas flows back to the filter wall of the filter tube 36. It is done by

The ejection of air from the ejector nozzle 40 is controlled such that the valve opening time (the time required from fully closed to fully opened and fully closed) is usually set to 0.1 to 0.5 seconds, as in the case of the tube type dust remover. By a valve (not shown). The dust blown off from the upper dust removal unit 38 by the backwash is sent to the lower portion along with the gas flow without staying in the upper space of the dust removal chamber 50, and a part of the dust is captured by the lower dust removal unit 38, but most of it is captured. Fall into the hopper section 42.

When backwashing the dust removing units 38 on either the left or right side shown in FIG. 3, backwash gas is ejected from the dust removing units, and the gas flow in the dust removing chamber 50 and the hopper section 42 is disturbed for a moment. Since the dust-containing gas is constantly extracted from the suction port 45, the original flow state is immediately restored.

FIG. 4 is a vertical cross-sectional view of another embodiment of the tube type dust remover of the present invention. In the figure, 21 is an orifice, 22 is an R (R) portion, 23 is a gas passage, and 25 is a gas passage.
Is a suction port, and 28 is a suction port. That is, the gas introduction port 10 is provided with the orifice 21 and the R (R) part 22, and the suction port 28 is opened immediately downstream of the orifice 21. The orifice 21 and the R (R) part 22 function as a diffuser. It is designed to work. As other variations, various configurations can be considered within the scope of the present invention, such as forming an ejector in the space around the guide tube.

FIG. 5 is a vertical cross-sectional view of another embodiment of the candle type dust remover according to the present invention, in which 52 is an R portion provided at the gas inlet 32. In this case, even if the orifice is not provided, the function of the diffuser is exerted only in the R portion.

Test Example An example of the test results when the dust remover according to the present invention is applied to a three-stage tube type dust remover provided in a pressurized fluidized bed boiler and when not applied is introduced below.

1) When the dust remover of the present invention is not used (in the dust remover of FIG. 1, the means for recirculating dust-containing gas is omitted): When the boiler load starts to increase, the gradient of filtration differential pressure (unit: unit) (Increment of filtration differential pressure per time) has become 7 times, oxygen concentration has sharply decreased, and a large amount of unburned components are being generated and it is assumed that they are coming in. The boiler load becomes 75% after 5 minutes. Reached

One minute after that, the temperature of the lower clean gas chamber, which was the same as the temperature of the other clean gas chambers until then, suddenly became higher than the temperature of the other clean gas chambers, and three minutes later, It began to fall after the temperature of the clean gas chamber increased by 40 ° C. From this experience, it was determined that the dust containing unburned components adhering to the inner surface of the filter tube in the lower clean gas chamber was burned.

Immediately after that, it was observed that the filtration differential pressure dropped sharply and black smoke was emitted from the exhaust stack downstream. Immediately after stopping the operation of the boiler and inspecting the inside of the dust remover, one of the lower filter tubes (made of cordierite ceramic with an outer diameter of 17 cm, an inner diameter of 14 cm, and a length of 3 m) was within a range of about 70 cm from the bottom. The filter tube was broken and was broken into many small pieces. It was judged that the filter tube was damaged by the thermal stress caused by the burning of the unburned components in the dust from the condition of cracks and other factors.

2) When using the dust remover of the present invention: 10% of the flow rate of the dust-containing gas flowing into the gas inlet of the dust remover configured as shown in FIG. 1 was circulated from the hopper to the gas inlet to operate. . Even if the boiler load was increased and the load was switched to 75% by switching from light oil combustion to coal combustion, the temperature inside the filter tubes in all the lower clean gas chambers was stable as in light oil combustion. Even if the boiler load was increased, the filtration differential pressure and the temperature in the clean gas chamber in the lower stage did not increase in comparison with the temperatures in the clean gas chambers in the other stages. After that, the boiler load was increased from 75% to 100%, and the operation was continued for about 48 hours in total, and then stopped.

As a result of inspection by opening the clean gas chamber in the lower stage of the dust remover, no abnormality was found in the filter tube. Further, there was no evidence that a large amount of dust had accumulated on any part of the filter tube in the dust removing device.

[0074]

EFFECTS OF THE INVENTION If the dust remover for high temperature gas according to the present invention is used for dust removal of high temperature dust-containing gas produced in a combustion process such as a power plant by a pressurized fluidized bed boiler, a coal direct combustion device or a coal gasification plant, , Even if dust-containing gas with a high dust concentration is introduced, there is no phenomenon that a large amount of dust accumulates on the filtration surface of the ceramic filter, and even if dust containing a large amount of unburned components such as soot is introduced, the filter Since it can be safely used without suffering thermal stress damage to the pipe, and the timing of full-scale commercialization of these future coal utilization technologies can be accelerated, its utility value in the energy industry is enormous.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a high temperature gas dust remover of the present invention.

FIG. 2 is a vertical cross-sectional view showing another embodiment of the high temperature gas dust remover of the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a vertical sectional view showing another embodiment of the dust remover for high temperature gas according to the present invention.

FIG. 5 is a vertical sectional view showing another embodiment of the high temperature gas dust remover of the present invention.

[Explanation of symbols]

1: Tube type dust remover 2, 34: Pressure vessel 3, 36: Tubular ceramic filter (filter tube) 4, 35: Heat insulating material 5a, 5b, 5c, 5d, 39: Tube plate 6: Gas inlet chamber 7, 42: Hopper part 8, 44: Diffuser 9a, 9b, 9c: Clean gas chamber 10, 32: Gas inlet 11a, 11b, 11c: Clean gas outlet pipe 12, 33: Clean gas outlet 13, 23, 43: Gas passage 14a, 14b, 14c, 18, 40: Ejector nozzle 15: Skirt 16, 25, 45: Suction port 17, 49: Ejector 19, 46: Diffuser inlet part 20, 28, 48: Suction port 21: Orifice 22, 52: R ( R) part 31: Candle type dust remover 37: Clean gas header 38: Dust removal unit 41: Guide tube 47: Throttling tube 50: Dust removal chamber 51: Clean Gas space

Claims (6)

[Claims] 1. A hopper having a ceramic filter built in a container, a backwashing means for regenerating the ceramic filter by brushing off the dust captured by the ceramic filter, and a lower part of the container for collecting the dust blown off. In the dust removing device, the diffuser is attached to the dust-containing gas introduction portion of the container or the dust-containing gas introduction pipe, and a gas passage that connects the inlet portion of the diffuser and the hopper portion is provided. A high temperature gas dedusting device, characterized in that a part of the dust-containing gas is configured to flow back to the dust-containing gas introduction portion of the container through a gas passage and a diffuser. 2. The ceramic filter according to claim 1, wherein the ceramic filter is a tubular ceramic filter, the interior of the container is partitioned by a plurality of horizontal tube plates, and a gas inlet chamber is provided above the uppermost tube plate. A dust remover for high-temperature gas, wherein tubular ceramic filters are respectively held at their ends by a tube sheet, and dust-containing gas is configured to flow inside the tubular ceramic filters. 3. The dust removing unit according to claim 1, wherein the ceramic filter is a tubular ceramic filter whose one end is closed, and a plurality of tubular ceramic filters are attached to a lower side or an upper side of the clean gas header in a substantially vertical direction to provide one or two dust removing units. A dust remover for high temperature gas, which is disposed in one or more containers and is configured to remove dust-containing gas while sequentially descending from the top of the dust remover unit. 4. The dust remover for high temperature gas according to claim 1, wherein the diffuser is a part of the ejector. 5. The dust remover for high temperature gas according to claim 1, wherein the container is a pressure container, and the gas passage is provided inside the pressure container. 6. The dust remover for high temperature gas according to claim 1, wherein the dust-containing gas to be dust-removed is combustion gas of a pressurized fluidized bed boiler.