JP6945339B2 - Flue gas purification and reheating methods and equipment - Google Patents

Description

The present invention relates to a method for purifying and reheating flue gas, in which a high temperature flue gas radiates heat through a heat exchanger, then a flue gas purifier, and then absorbs heat. While passing through the heat exchanger, it is further supplied to the flue gas. The present invention further relates to a purifying and reheating device for flue gas flowing in a predetermined flow direction, which device comprises a heat exchanger casing through which the reheating gas passes and a heat exchange member.

Such methods and devices are used, for example, to purify flue gas in coal or petroleum-fired power plants (both abbreviated as "power plants").

An object of the present invention is to prevent contamination of the heat exchanger by hard solid deposits. These solid deposits increase the pressure loss in the heat exchanger, incur significant cleaning costs and, in the worst case, may even force the power plant to shut down for an undesired short period of time.

Power plants typically reheat flue gas downstream of the flue gas purifier in order to expel flue gas, residual sulfuric acid and microdust contained in the flue gas into the atmosphere as high as possible. The device is equipped. Without this reheating, usually condensed water is already formed in the chimney. This condensed water usually occurs on the wall of the chimney or near the wall of the chimney and then aggregates to form large droplets. In addition, large wash water droplets resulting from the cleaning of the droplet separator of the flue gas purifier are also carried into the chimney along with the flue gas and then discharged from the chimney. If the flue gas was reheated, the droplets and wash water droplets would have been evaporated in the heat exchanger. The droplets (large condensed water droplets and large cleaning water droplets) are then discharged from the chimney and scattered in the immediate surrounding environment.

This so-called stack rain is naturally acidic (sulfuric acid as a component), due to corrosion, vehicles (paint damage and corrosion), buildings (decomposition of concrete and building materials), severe damage to (industrial and private) facilities, and plants and gardens. It may also cause damage (acid rain). This, of course, must be absolutely avoided, especially in residential areas. It is conceivable that there will be constant conflict with local residents who have no choice but to watch the destruction of private cars, houses, business facilities, etc. by acid rain.

This problem is avoided by reheating the flue gas to avoid the formation of condensed water and by reheating the droplets to evaporate and condense for the first time outside the chimney. The flue gas heats up and rises, and the condensed water remains small at first and then evaporates in the surrounding air before reaching the ground.

For decades, so-called Jungstrom heat exchangers (rotary regenerative heat exchangers) have been used for reheating. Jungstrom heat exchangers consist of a maximum number of heat exchanger surfaces, which first absorb heat in the hot raw gas stream upstream of the flue gas purifier ( It also cools the flue gas), then makes a half turn to supply heat again to the clean gas arriving from the flue gas purifier in the countercurrent. The heat exchanger surface absorbs and stores heat from the hot raw gas stream, then rotates further into the countercurrent, and then supplies the stored heat to the countercurrent again.

This regenerative heat exchanger has the following drawbacks in particular.

During raw gas heating, this heat exchanger absorbs not only heat but also dust components. In addition, regenerative heat exchangers are sparse and leaky, and high temperature raw gas may leak into a clean, low temperature clean gas stream through the leak. Based on these two actions, a predetermined amount of dust components that would have been separated in the flue gas purification device are brought into the flue gas flow to increase the dust load, and the downstream side of the flue gas purification device. The clean gas is still dust-loaded.

This is of course undesirable and power plant dust emissions should be minimized. Therefore, it is not desirable to contaminate the clean gas with fine dust through such a leak in the regenerative heat exchanger.

Therefore, the concept of a leak-free heat exchanger was developed. Such a heat exchanger may be formed as a gas / gas-heat exchanger and may have a tubing system through which raw gas flows on the inside and clean gas passes on the outside. However, the heat exchanger may also be formed as a gas / liquid-heat exchanger. In the case of gas / liquid-heat exchangers, the two gas streams are separated by a single liquid circuit, which transfers heat from the raw gas to the clean gas. Flue gas passes through a tubular or plate heat exchanger with a liquid on one side and a transport liquid on the other side. The hot raw gas supplies its heat to the coolant. The liquid is then guided to the clean gas side, where the heat is again returned to the clean gas in a similar tubular or plate heat exchanger.

Leakage of raw gas and fine dust components to the clean gas side cannot occur in both of the above configurations of the heat exchanger.

However, the experience of operating these leak-free heat exchangers has been that the heat exchangers can be severely contaminated during operation. Deposits are formed on the surface of the heat exchanger through which the flue gas flows. These deposits consist of gypsum, limestone, microdust, and other components of the flue gas or, more precisely, the residual droplets in this flue gas, often with the surface of the heat exchanger and strong. It has a rigid structure as well as being bonded to, and also has a partially crystalline structure. Deposits are particularly formed where the flue gas stream flows into the surface of the heat exchanger.

As a result of these deposits, the pressure loss increases and the heat exchange capacity decreases.

The deposits grow larger and larger over time and invade and multiply in the path of flue gas through the tubes or plates of the heat exchanger. As a result, the passage space for the flue gas is narrowed, the speed is increased, and the pressure loss is increased. Moreover, the rate of contamination (ie, the formation of deposits) increases as the thickness of the deposits increases. The deposits create a vortex in the free passage between each heat exchanger surface, thus allowing more liquid to hit the heat exchanger surface and adhere to it. The increase in pressure drop may be so rapid that the boiler must be adjusted downwards or shut off completely. And, of course, a large increase in pressure loss leads to a considerable operating cost. The flue gas fan must operate against this pressure loss, forcing it to consume significantly more current than under normal clean conditions. This self-consumption reduces the output to be allocated and thus the sales and profits of the power plant.

The heat exchange capacity diminishes over time and reheating no longer works. The deposits usually do not conduct heat very well and act as an insulating layer between the flue gas and the surface of the heat exchanger.

In addition, corrosion often occurs in connection with deposits. The exposed, relatively clean surface of the heat exchanger shows little or no corrosion, whereas significant corrosion often occurs under the deposits. The deposits actually act like a protective layer under which the corrosive liquid can act on the heat exchanger surface and corrode the heat exchanger surface.

Cleaning contaminated heat exchangers is generally difficult. The deposits are not only extremely hard, but may also be tightly bound to the surface of the heat exchanger member. This bond must be broken by mechanical force and the deposits need to be removed by high pressure washing. Not only is this extremely laborious, but it also leads to damage to the heat exchanger material. This is because the peeling force of the high pressure washer not only peels off the deposits but also completely peels off the surface of the heat exchanger. This shortens the life of this relatively expensive heat exchanger.

Moreover, this wash is extremely time consuming and can last for much longer, not just hours. Pauses to clean the heat exchanger should not normally be done. That is, if the pressure loss increases significantly before the end of the operation cycle and the heating by heat is hindered in connection with this, it is inevitable to stop the operation for a relatively long period of time.

The cleaning is also extremely expensive. The members of the heat exchanger to be cleaned, such as tube bundles or plate bundles, are in fact inaccessible and need to be lifted many times from their position for cleaning. Therefore, in this case, a crane having a considerable lifting force is required. Even a clean bundle already has a considerable weight, so as the contamination progresses, the bundle becomes heavier and heavier. And cleaning a special place requires a considerable amount of time and manpower, depending on the nature and thickness of the deposits.

Unfortunately, it is usually impossible to remove all deposits. For that purpose, normal inspection does not have enough time and manpower. Moreover, the surface of the heat exchanger located inside can only be reached in a very limited manner. The residual deposits remaining in the heat exchanger in this case act to accelerate the formation of new deposits. Furthermore, cleaning with a high pressure washer roughens the surface of the heat exchanger, which also accelerates the formation of new deposits. The rough surface and the residual deposits serve to promote or accelerate the adhesion. New deposits can deposit on these rough or residual deposits more rapidly than on smooth, clean surfaces.

In addition, the cleaning means promotes damage to the heat exchanger. On the one hand, it can cause peeling and damage to the surface of the heat exchanger, and on the other hand, it can lead to expansion and recombination to other damage in the structure of the heat exchanger. The life of the heat exchanger is shortened. Experience has shown that a single wash has the effect of significantly shortening the life of the product compared to 12 months of operation.

These experiences led to a ponder on the cleaning equipment, which led to the incorporation of the cleaning equipment. The purpose of these cleaning devices is to prevent or delay contamination, thus ensuring the operation of the power plant during the period of operation and, on the other hand, reducing operating and cleaning costs.

The cleaning device was initially installed only on the upstream side of the heat exchanger bundle on the upstream side when viewed in the flow direction of the flue gas. The experience was that in this case the prominent and most violent deposits were formed. Initially working with compressed air and steam, it was quickly confirmed that this did not produce the desired effect of prolonging the operating time. Next, it was washed with high pressure water.

Cleaning with high pressure was actually able to significantly reduce the contamination of the upstream bundles. The deposits could not be completely avoided, but they were no longer violently formed. First, the increase in pressure loss was avoided and the heat loss was kept within the limit.

However, we have also experienced deposits on the bundles located further downstream of the heat exchanger, that is, in areas that were previously completely or relatively slightly affected. These deposits were generated with some delay (relatively long operating time), which significantly increased the cleaning effort in terms of time and cost.

Some power plants were also additionally equipped with multiple cleaning systems. There was no space for that at another power plant. In the latter power plant, for cost reasons, each passage filled with heat exchangers was formed as small and densely as possible.

However, from that point on, it was recognized that the deposits were only "only" shifted further downstream toward another heat exchanger bundle by another cleaning device, and the cleaning effort or damage to the heat exchanger was further increased. Has also taken root. In addition, multiple cleaning systems lead to considerable investment and operating costs. Ultimately, each wash naturally results in immediate cooling of flue gas, influx of liquid into the chimney, and then influx into the environment. However, this is exactly what should be avoided.

It has become established that multiple cleaning systems may not actually perform the desired function. On the one hand, investment costs and operating costs have increased, and on the other hand, cleaning means are only limited and sufficient, and on the contrary, the cleaning costs have increased in the stopped operation state.

The explanation for these malfunctions of the cleaning device is relatively simple. When droplets contaminated with solids hit a heated or even hot surface, some of the liquid remains on the surface and wets the surface. The liquid is then evaporated by the constantly supplied heat, leaving only the solids. When this solid matter evaporates, it binds to the surface of the heat exchanger and invades and fills the minute gaps and holes on the surface. Over time, it then grows into extremely thick and hard deposits.

When such formation of deposits is reduced by cleaning, cleaning droplets having the same function as the original droplets arriving from the flue gas purifier are generated further downstream in the heat exchanger. When the final heat exchanger is also cleaned, the cleaning droplets will jump into the aisles and chimneys and then scatter into the surrounding environment as stack rain.

That is, the cleaning action of the cleaning system at one location leads to the contamination action at the other location. Then, the temporary cooling of the flue gas during cleaning or the temporary release of the cleaning liquid from the chimney cancels out the heating action again and leads to an environmental disturbance that should be avoided by heating. On the contrary, in some cases there are problems with the regulatory agency. This is because, in the above case, the standard value of the authorities cannot be met temporarily.

Therefore, from these experiences, it can be summarized that cleaning of heat exchangers should be avoided. This is because cleaning during operation involves more problems and costs than benefits.

Therefore, it was considered to arrange the flue gas purification device on the upstream side of the heat exchanger in yet another target direction. This view that improved separation can reduce the amount and rate of pollutant formation was quite correct. As a result of this consideration, the droplet separator of the flue gas purifier was formed in three stages, and in some cases four stages, and the function of the droplet separator was improved by another equipment-specific means. ..

This has certainly made progress. The amount of deposits decreased and the formation of deposits slowed down. The improved droplet separator, on the one hand, allowed less droplets to pass through during operation (improved separation function), and on the other hand, the contamination of the droplets with solids was reduced on average.

Triple or even quadruple droplet separators simply have better separation function than double droplet separators. It is clear that any droplet separator collects only 98% to 99.9% of relatively large droplets and never 100%. More steps mean a higher degree of separation.

Further, in this way, the amount of solid matter in the droplet is also reduced. Most of the droplets downstream of the droplet separator have been stripped from the final droplet separator cleaning process. If this last droplet separator is relatively heavily contaminated, the exfoliating wash droplets will also be heavily contaminated with solids. Conversely, if the last droplet separator is uncontaminated and extremely clean, the cleaning droplets are also slightly contaminated. In other words, if a 3-stage or even 4-stage droplet separator with high cleaning ability is provided, the final stage cleaning entrainment is significantly more contaminated than the cleaning entrainment generated from the 2-stage droplet separator. It is decreasing.

In short, the improved separation was able to significantly reduce the formation of deposits. This allowed most equipment to operate uninterrupted in one complete run cycle. However,
Two problems remained: 1) considerable cleaning effort and 2) constantly formed pressure drop.

It was found that the above method had reached its limit and no further improvement was possible.

Therefore, an object underlying the present invention is to provide an improved method for the above-mentioned problems and an apparatus suitable for carrying out the method. The separation concept found for this is:
1. 1. High separation capacity for large droplets is permanently guaranteed. That is, the progress of contamination does not reduce the separation capacity.
2. Cleaning peeling must be avoided. In the conventional equipment, the cleaning ability for fine dust is doubled by avoiding the cleaning peeling which is the cause of 60% to 70% of the total liquid peeling.
3. 3. No increase in pressure loss should occur. The increase in pressure drop caused by the formation of deposits is avoided,
It meets the three conditions.

There are various droplet separator concepts that can separate droplets from flue gas, one of which is a multi-layered droplet separator with various configurations provided in an absorber as a prior art.

A particularly successful initiative is the so-called "roller separator". Unlike conventional laminated plate separators, roller separators use tube segments as collision bodies, and extruded, specially molded members are used for these tube segments.

It has been found that this roller separator is extremely resistant to dirt and deposits during operation and nevertheless provides a relatively acceptable separation capability for the separation of conventional laminate separators. However, roller separators have generally been used only as coarse separators in the past. This is because the laminated plate separator is superior to the roller separator when used as a fine separator.

Roller separators have traditionally been primarily used to purify existing droplet separators. During that time, we were able to accumulate sufficient experience in these purified equipment to serve as a basis for use in new equipment.

It is well known that particularly large droplets induce the action of deposit formation.

No small droplets reach the surface. Small droplets have a small mass, so they dodge heat exchanger tubes or heat exchanger plates with flue gas, fly around them, and do not collide. The heat supply then evaporates the small droplets and the solids continue to fly as microdust.

Medium-sized droplets either partially dodge the flow resistance, depending on the flight path, or contact only the surface of the heat exchanger, then are often split into multiple partial droplets that continue to fly with the flue gas. After that, it still evaporates.

Only large droplets hit the hot surface of the heat exchanger without being able to dodge the flow resistance of the heat exchanger tube or heat exchanger plate based on its mass. There is then a temporary wetting of a small surface area, which subsequently evaporates on the surface, leaving a tightly bonded hard coating.

The large droplets are large cleaning droplets that are generated and detached by the final separator cleaning, or are ceilings, walls, or another in the flue gas passage between the separator and the heat exchanger. Large condensed water droplets that peel off from the peeling edge. These condensed water droplets are generated because the ambient temperature is significantly lower than the flue gas temperature, and even if the flue gas passage is well insulated, a considerable temperature difference acts. Delamination may accumulate on the wall and agglomerate before it is exfoliated again.

Condensed water droplets also have some solid content. Dust also accumulates on the walls and ceiling of the flue gas passage, which, in the form of partially dry dust, continues to remain in contact with the wet surface and, in part, also in contact with the surface. It is due to the small droplets having a solid component that are deposited there. If sufficient liquid from the condensed water and deposits adheres, the droplets will separate back into the flue gas and fly towards the heat exchanger.

It is not possible with conventional droplet separators to prevent these large droplets from reaching the heat exchanger or to pre-remove the large droplets from the flue gas stream. Ordinary separators are provided with a laminate and are located in the absorber, which has the disadvantage of facilitating deposition on the laminate, which also forms deposits until occluded. Further, a considerable amount of condensed water may be generated between the absorber and the heat exchanger depending on the temperature condition of the surrounding environment.

In order to take measures against this, in the flue gas purification and reheating method according to the present invention, the high-temperature flue gas radiates heat and passes through the heat exchanger, and then passes through the flue gas purification device. After that, the heat exchanger is passed through while absorbing heat, and then it is supplied to the chimney, and the flue gas is arranged on the downstream side of the flue gas purifier and on the upstream side of the heat exchanger when viewed in the flow direction. Guided through an additional liquid separator.

That is, the relative proximity of the additional liquid separator to the heat exchanger results in the formation of condensed water droplets between the liquid separator and the heat exchanger, which then form the condensed water droplets in the heat exchanger as described above. It is avoided to bring about the pollution problem.

Preferably, in the means of constructing the method according to the invention, the flue gas passes through the heat exchanger in a substantially horizontal direction while absorbing heat.

In a particularly preferred improvement of the method according to the invention, the liquid separator has a plurality of elongated three-dimensional colliding bodies, the longitudinal extension of these colliding bodies in the direction of flue gas flow. On the other hand, the size and arrangement of the colliding bodies diagonally or laterally and diagonally or laterally with respect to the longitudinal extension of the colliding body are such that each colliding body is flue gas as seen from the projection. It is set to overlap in the flow direction of the flue gas, which prevents the flue gas from passing through the liquid separator without changing the flow direction.

The present invention also relates to a purifying and reheating device for flue gas flowing in a predetermined flow direction, which device comprises a heat exchanger having a heat exchanger casing for reheating the heat exchanger. Gas flows through, and a liquid separator is arranged in the heat exchanger casing on the upstream side of the heat exchanger when viewed in the flow direction of the flue gas. By arranging the liquid separator within the heat exchanger casing, on the one hand, the liquid separator is relatively close to the heat exchanger in favor of carrying out the method according to the invention. On the other hand, the flow rate of flue gas through the heat exchanger is relatively low due to the normally relatively large volume of the heat exchanger casing, and thus the inflow rate into the liquid separator is also relatively high. The lower result provides improved separation capability for large droplets.

Surprisingly, it has been found that liquid separators with multiple colliding bodies are particularly suitable for use within heat exchanger casings.

It is extremely preferable that the colliding body is elongated and three-dimensionally formed, preferably, for example, a tubular shape. Such a liquid separator is also referred to as a "roller separator". The roller separator itself is known to have relatively poor separator capabilities, so the use of such a roller separator in the heat exchanger casing seems meaningless at first glance. I was broken.

Nevertheless, it is suggested to use a roller separator as a protective measure for the heat exchanger. As is well known, the roller separator is a poor separator as compared with the laminated plate separator. So this is inconsistent with the current teaching that the last separator must provide the best separation capability.

In practice, the current teachings should be modified based on the present invention. That is, the separation capacity must be gradually increased, and the current teaching in which all the droplet separators are continuously incorporated in the absorber causes a jam. Current teachings do not take into account that certain separation capacities cause greater contamination when the gas contains solids than when unavoidable cleaning is reduced. Furthermore, the arrangement format is also a problem.

In other words, such an droplet separator is extremely contaminated and must be cleaned frequently, as the improvement in separation capacity in the final stage results in very small spacing between the separation laminates. Cleaning causes severe delamination, which causes more debris than the detergency-enhanced separator stage filters from flue gas. In other words, it is inevitable to go one step further and take two steps down.

Therefore, the solution according to the present invention goes the opposite way. Surprisingly, the specific separation capabilities of the entire system have shown that cleaning produces most of the emissions, especially in heat exchangers, which produces annoying deposits leading to blockages.

Therefore, an object of the configuration according to the present invention is to find a solution that does not require cleaning of the final separation stage at all. In this case, it is considered that the final stage provides a relatively poor separation capacity.

It was found that the inside of the roller separator was kept completely clean without cleaning or was slightly contaminated even during long-term operation. And this contamination of the rollers has little effect on the total amount of delamination from the separator system.

In addition, roller separators have been found to be particularly suitable for use as a protective measure on the upstream side of reheating heat exchangers. It can be explained that the roller separator can separate particularly large droplets well. As mentioned above, the main role of the final separator is exactly to collect and separate the stripped wash droplets of the separator located upstream. As is well known, these washing droplets are rather large to extremely large droplets.

Also, placing the roller separator inside the heat exchanger casing results in a rather low flue gas velocity, based on the size of the heat exchanger casing, which results in a droplet separator and heat exchanger. It was also confirmed that negative effects such as condensed water between the two were avoided.

In this case, it was found that the drawback that the small droplets produced by the separation stage located on the upstream side are not separated can be ignored. These small droplets occupy only a relatively small portion of the amount of liquid reaching the roller separator. Depending on the cleaning frequency, 90% to 99% of the liquid amount is separated from the cleaning process of the separation stage located on the upstream side.

A liquid separator formed as a roller separator must have staggered tubes (or tubular impactors) consisting of at least two layers, which completely block the path in the flow direction. That is, they are configured to overlap each other. This ensures that at least the majority of the large droplets hit the impactor.

Preferably, the roller separator has three or four tube layers. The third and fourth tube layers are particularly significant when the separator is installed very close to the heat exchanger. In this case, the third layer and, in some cases, the fourth layer capture the radiant heat of the heat exchanger to prevent the droplets on the collision tube from evaporating after the first tube layer is heated. ..

The separator should be installed as close to the heat exchanger as possible. Normally, the flue gas passage extends upstream of the heat exchanger. This is because, in general, the flue gas velocity in the heat exchanger must be lower than in the aisle. Tube separators also require the lowest possible flue gas velocities to function well. Furthermore, in this case, no condensed water droplets are expected anymore between the separator and the heat exchanger. The radiant heat of the heat exchanger is usually sufficient to keep the passages dry at intervals of up to 2.5 m, i.e. to avoid condensate water. However, if the distance to the heat exchanger is less than 0.5 m, it may lead to heating of the tube separator, and this heating is not desirable. This is because, in that case, the tube separator may have a drying process that may reduce the function of the tube separator and increase the pressure loss.

Therefore, the distance between the liquid separator and the heat exchanger is preferably 0.5 m to 2.5 m, preferably 1 m to 2 m, and particularly preferably about 1.5 m.

The heat exchanger may be particularly preferably formed as a leak-free, particularly gas / gas-heat exchanger.

Further, a cleaning system may be provided for cleaning the liquid separator as needed, but this cleaning system is preferably operable, especially when the device is stopped.

The present invention will be further described with reference to the accompanying drawings.
FIG. 5 is a schematic partial cross-sectional view of a flue gas purification and reheating device having a heat exchanger, a flue gas purification device, and a molded brick (chimney). It is also the figure which showed by enlarging a part of the heat exchanger of the apparatus by this invention.

In the device shown in FIG. 1, high-temperature flue gas (also referred to as “raw gas”) generated from a power plant (not shown) passes through the supply conduit 1 in the flow direction S and toward the heat exchanger 2. It flows.

The heat exchanger 2 has a heat exchanger casing 3 and a heat exchanger member 4. The heat exchanger member 4 is formed in a tubular shape in the illustrated embodiment, and the high-temperature flue gas passes through while radiating heat.

The raw gas cooled at this time is then supplied to the flue gas purification device 6 via the outlet pipe 5. The flue gas purification device 6 has a plurality of droplet separation units 7, and the cooled raw gas is purified by flowing through these droplet separation units 7 from below to so-called. Becomes clean gas. The flue gas purification device 6 may have a cleaning device for the droplet separation unit (not shown). The cooled clean gas is introduced into the heat exchanger casing 3 via another supply conduit 8. Inside the heat exchanger casing 3, a liquid separator 9 is provided on the upstream side of the heat exchanger member 4 when viewed in the flow direction. The liquid separator 9 may have a plurality of tubular colliding bodies 10 extending laterally with respect to the gas flow direction S (as seen in FIG. 2).

In the embodiment shown in FIG. 2, the colliding bodies 10 in three rows 11, 12, and 13 are provided. The colliding bodies 10 are dimensioned and arranged so as to overlap in the flow direction when viewed from the projection drawing in the flow direction.

After passing through the liquid separator 9, the clean gas flows while absorbing heat around the outer periphery of the heat exchanger member 4.

The reheated clean gas is then supplied to the chimney 15 via another outlet pipe 14.

1 Supply conduit 2 Heat exchanger 3 Heat exchanger casing 4 Heat exchanger member 5 Outlet pipe 6 Smoke path gas purification device 7 Droplet separation unit 8 Supply conduit 9 Liquid separator 10 Collision body 11, 12, 13 rows 14 Outlet pipe 15 Chimney S Flow direction

Claims (10)

A method of purifying and reheating flue gas, in which high-temperature flue gas dissipates heat and passes through a heat exchanger (2), then through a flue gas purifier (6), and then absorbs heat. In a method in which the heat exchanger (2) is passed through the heat exchanger (2) and then supplied to the flue gas (15).
The flue gas purification device (6) has a droplet separation unit (7).
The flue gas passes through the liquid separator (9) on the downstream side of the flue gas purifier (6) and on the upstream side of the heat exchanger (2) when viewed in the flow direction (S). A method for purifying and reheating flue gas, which comprises. The method according to claim 1, wherein the flue gas passes through the heat exchanger (2) in a substantially horizontal direction while absorbing heat. The liquid separator (9) has a plurality of elongated three-dimensional colliding bodies (10), and a longitudinally extending portion of these colliding bodies (10) is formed in the flow direction of the flue gas (10). The size and arrangement form of the colliding body (10), which is oriented diagonally or laterally with respect to S) and diagonally or laterally with respect to the extending portion in the longitudinal direction, can be seen in the projected view. The colliding bodies (10) are set so as to overlap each other in the flow direction (S) of the flowing flue gas, whereby the flue gas separates the liquid without changing the flow direction. The method according to claim 1 or 2, wherein the vessel (9) cannot be passed through. A cleaning and reheating device of the flue gases flowing in a predetermined flow direction (S), and the heat exchanger casing (3) and a heat exchanger member provided on the heat exchanger casing (3) in In those provided with a heat exchanger (2)
The high-temperature flue gas dissipates heat and passes through the heat exchanger (2), and then absorbs heat and passes through the heat exchanger (2).
The liquid separator (9) is arranged in the heat exchanger casing (3) on the upstream side of the heat exchanger member (4) when viewed in the flow direction (S) of the flue gas. A flue gas purification and reheating device. The device according to claim 4, wherein the liquid separator (9) has a plurality of colliding bodies (10). The collision member (10) is made form the elongated three-dimensional apparatus of claim 5, wherein. The device according to claim 6, wherein each of the colliding bodies (10) is formed so as to overlap each other in the flow direction (S) as viewed from a projection drawing. The apparatus according to any one of claims 4 to 7, wherein the minimum distance between the heat exchanger member (4) and the liquid separator (9) is 0.5 m to 2.5 m. The device according to any one of claims 4 to 8, wherein the heat exchanger (2) is formed as a gas / gas-heat exchanger without leakage. Cleaning system for cleaning the liquid separator (9) as required when stopping of those said device is provided, apparatus of any one of claims 4 to 9.

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