JP4823043B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger used for cooling a pressurized high-temperature gas or the like. For example, a heat exchanger used in a pressure vessel such as a coal gasification furnace, an oil gasification furnace, or a biomass gasification furnace is provided. The present invention can be applied to a gasification cooler or a heat recovery device for pressurized hot gas.

2. Description of the Related Art Conventionally, in a coal gasification combined power generation system (IGCC), a coal gasification furnace facility that gasifies fuel such as coal in a gasification furnace to generate a high-temperature gas is known.
However, since the produced gas of the coal gasification furnace contains a large amount of dust such as char and slag, there is a problem that this dust adheres to the heat transfer tube and reduces the heat recovery efficiency.

Increasing the flow rate of the product gas is effective as a technique for suppressing dust adhesion to the heat transfer tubes. There are the following known techniques as conventional techniques for realizing this.
As a first known technique, a method of installing a partition plate in a product gas flow path has been proposed. (For example, see Patent Document 1)
As a second known technique, there has been proposed a method of expanding the effective area of the heat transfer tube by installing fins on the heat transfer tube. (For example, see Patent Document 2)

As a third known technique, there is a method of obtaining the effect of suppressing the dust accumulation on the heat transfer tubes by making the flow direction of the product gas a return flow type and not excessively increasing the vertical duct area. Proposed. (For example, see Patent Document 3)
JP 2004-51915 A JP-A-2-21197 JP 2006-214712 A

However, the following technical problems have been pointed out with respect to the above known technique.
The first known technique has a technical problem that the height of the apparatus becomes very large due to the configuration in which the product gas cooling apparatus is arranged in the upper part of the gasification furnace.
In general, the gas flow rate increases at a portion where the pressure loss is low, but in the above-described known technique in which a partition plate is installed between the heat transfer tube groups, the generated gas flow rate increases near the partition plate without the heat transfer tube.
For this reason, the flow rate of the product gas in the heat exchange portion is lower than before the partition plate is installed, and dust is likely to accumulate in the tube group. In addition, since the generated gas flows in parallel with the heat transfer tubes, dust tends to accumulate toward the lower side of the tube group due to gravity.
Further, on the upper side of the partition plate, a stagnation region is generated near the plate due to the influence of the secondary flow toward the inlet side. For this reason, ducts may accumulate on the partition plate above the partition plate on the inlet side.
As described above, the heat transfer tube that is not closed has a higher heat load, and the closed heat transfer tube has a lower load, so the non-uniformity of the heat load distribution in the tube group is remarkable. Since the life of the product is determined on the high load side, it is considered that the first known technology with remarkable non-uniformity of the heat load does not have a sufficient life as a product.

In the second known technique, by installing fins in the heat transfer tube, the heat transfer area is expanded and the heat recovery efficiency is improved. Since the flow path area between the fins is reduced by the installation of the fins, the gas flow velocity in this portion is considered to be high. After passing through a narrow portion between the fins, the flow path area suddenly expands, so that a back flow of the secondary flow toward the fins occurs and forms a stagnation region. Dust tends to accumulate in this stagnation area, and the problem of promoting blockage of the tube group has been pointed out by installing fins.
The third known technique is that the flow direction of the product gas is a return flow type, the duct area in the vertical direction is not excessively increased, and the gas flow rate is increased, so that the cooler is made compact and the dust is deposited on the heat transfer tubes. It is possible to obtain the suppression effect.
However, because of the return flow type, there is a duct elbow at each of the downflow and upflow inlets, and a stagnation region is formed inside the elbow due to the secondary flow of the product gas. For this reason, in the heat exchanger tube group on each inlet side, the heat transfer tubes on the inner side of the elbow are more likely to accumulate dust and the load is less likely to accumulate on the heat transfer tubes on the outer side of the elbow.

Thus, in a heat exchanger such as a gasification cooler that cools a generated gas containing a large amount of dust such as char or slag in the gas, such as a generated gas generated in a coal gasification furnace, for example. It is desired to prevent the tube group from being blocked due to dust accumulation and to eliminate the non-uniformity of the heat load that reduces the durability of the heat transfer tube.
The present invention has been made in view of the above circumstances, and the object of the present invention is to prevent non-uniformity of the heat load that reduces tube group blockage due to dust accumulation and reduces the durability of the heat transfer tube. It is to provide a heat exchanger that has been eliminated.

In order to solve the above problems, the present invention employs the following means.
In the heat exchanger according to the present invention, a flue for flowing a product gas introduced from a gasification furnace is formed in a pressure vessel, and a fluid flowing inside a heat transfer tube installed in the flue and the product gas A heat exchanger for exchanging heat, a solid triangular cross-section protrusion provided upstream of the heat transfer tube, and a solid and substantially rectangular cross-section secondary flow suppression provided on the downstream side of the heat transfer tube Means .

According to such a heat exchanger, the solid triangular section protrusion provided on the upstream side of the heat transfer tube and the solid and substantially rectangular cross section secondary flow suppression provided on the downstream side of the heat transfer tube. And means for preventing or suppressing dust contained in the product gas from accumulating on the heat transfer tubes.
In addition, by making the material of the protrusions better heat transfer tube material or equivalent heat transfer material, the thermal resistance between the product gas and the fluid in the heat transfer tube can be reduced, and the heat recovery efficiency Can be improved.
As the protrusion on the upstream side of the heat transfer tube, for example, by setting the angle of the apex in an inverted V shape to be smaller than the angle of repose during dust accumulation, dust accumulation can be effectively suppressed. However, since the thermal resistance between the generated gas and the heat transfer tube can be reduced even if the angle of the protrusion vertex is larger than the angle of repose at the time of dust accumulation, the heat recovery efficiency can be improved.
Such protrusions are desirably installed on all the heat transfer tubes, but when limited to a part of the projecting portions, it is desirable to provide the heat transfer tubes on the high dust concentration side.

And since the secondary flow suppression means is provided in the downstream of the heat exchanger tube which forms a heat exchanger, it is hard to produce a secondary flow in the downstream of the heat exchanger tube. For this reason, since a negative pressure region is not formed on the downstream side of the heat transfer tube, dust does not easily accumulate in the downstream region of the heat transfer tube, and the heat recovery performance does not deteriorate. Moreover, since a dust bridge is not formed between the heat transfer tube located on the downstream side, the heat recovery performance is not lowered even in the downstream heat transfer tube, and high heat recovery performance can be maintained.

In the above heat exchanger, an introduction flow path corner portion for introducing a high temperature gas into the flue, a discharge flow path corner portion for discharging a generated gas from the flue, and a partition wall for partitioning a vertical flow in the flue At least one of the flow direction changing part is provided with a product gas channel rounded to R shape, the radius of curvature of the rounded R shape, set to 1 / 10D~2D relative to the inner diameter D of the channel It is preferable that

According to such a heat exchanger, the introduction flow path corner section for introducing the high temperature gas into the flue, the discharge flow path corner section for discharging the generated gas from the flue, and the partition wall for partitioning the vertical flow in the flue. At least one of the flow direction changing part is provided with a product gas channel rounded to R shape, the radius of curvature of the rounded R shape, set to 1 / 10D~2D relative to the inner diameter D of the channel since it is, it is possible to prevent or suppress the formation of formation or stagnation zone of the secondary flow of hot gas produced in the flue.

Said heat exchanger WHEREIN: It is preferable to arrange | position the tube group of the said heat exchanger tube in the high flow-velocity part of the product gas which flows through the inside of the said flue .

  According to such a heat exchanger, since the tube group of the heat transfer tubes is arranged at the high flow velocity portion of the product gas flowing in the flue, the tube group can be used as a flow pressure drop resistor, and the heat of the tube group can be used. The load can be made uniform, and the shortening of the product from the planned life due to the uneven heat load can be suppressed.

According to the present invention described above, dust can be prevented or suppressed from accumulating on the heat transfer tubes forming the heat exchanger, so that tube group blockage due to dust is prevented and good heat recovery efficiency of the heat exchanger is maintained. It becomes possible.
In addition, since the non-uniformity of the heat load that reduces the durability of the heat transfer tubes forming the heat exchanger can be eliminated, the planned life of the heat exchanger is shortened due to the non-uniform heat load Can be suppressed.

Hereinafter, one embodiment of a heat exchanger concerning the present invention is described based on a drawing.
FIG. 5 is a schematic configuration diagram of a coal gasification facility used in an integrated coal gasification combined power generation system (IGCC), in which a coal gasification facility that gasifies fuel such as coal in a gasification furnace and generates high-temperature gas is shown. It has been known.
This coal gasification furnace equipment mainly comprises a coal supply equipment 100, a gasification furnace 200, a gasification cooler (heat exchanger) 300 of a gasification cooler that is a subject of the present invention, a char recovery equipment 400, and the like. As an element.

Here, as shown in FIG. 6, for example, the gasification cooler 300 is supplied with a generated gas of about 1100 ° C. containing char from the gasifying furnace 200, and this generated gas is supplied to the downstream side of the gasifying furnace equipment. Is a heat exchanger that cools to about 450 ° C., which is a temperature suitable for a gas purification facility (not shown), and recovers thermal energy from the generated gas.
In addition, the gasification cooler 300 includes an evaporator (EVA) 310, a secondary superheater (2SH) 320, and a primary in a flue 301 that is formed inside the pressure vessel 350 and serves as a flow path for product gas. The heat exchangers of the superheater (1SH) 330 and the economizer (ECO: economizer) 340 are arranged in order from the top, and are configured to absorb heat from the generated gas flowing from the top to the bottom in the flue 301 and cool it. Has been.

Such gasification coolers include what is called a return flow type.
The return flow type gasification cooler 10 shown in FIGS. 7 and 8 has a flue 20 formed by a peripheral wall 23 in a pressure vessel 11 having a circular cross section, and the internal cross section of the flue 20 is divided by a partition wall 30. It is. This return flow type structure has a first flue (down flow in the configuration of FIG. 7) 21 and a second flue (up flow in the configuration of FIG. 7) 22 formed by dividing the flue 20 by a partition wall 30. The generated gas generated in the gasification furnace equipment is introduced from the top of the pressure vessel 10, and the introduced gas introduced at the bottom of the pressure vessel 10 is folded and flows in the opposite direction. Can be reduced, and the apparatus can be made compact. Further, the folded portion 24 may be provided with a char recovery mechanism. In addition, about introduction | transduction and return | folding of product gas, it is good also as a structure where a top part and a bottom part are reverse.

In the example of FIG. 8, the heat insulating material 12 is attached to the inner peripheral surface of the pressure vessel 11, and the flue 20 is formed in the internal space of the pressure vessel 11. The cross-sectional area division ratio at which the flue 20 is divided into the first flue 21 and the second flue 22 is set so that the flow rates of the high-temperature gases that flow in opposite directions are substantially the same. This cross-sectional area division ratio is an ascending portion where the cross-sectional area ratio of the first flue 21 that is the descending portion that flows the introduced product gas into the downflow flows the product gas that is turned back at the bottom of the pressure vessel 10 into the upflow. The value is larger than the cross-sectional area ratio of the second flue 22 (for example, 2: 1).
In addition, the first flue 21 and the second flue 22 are each provided with a panel 50 through which a refrigerant flows to constitute a heat exchanger 40.

  In the first flue 21 at the descending portion where the product gas flows into the downflow, an evaporator (EVA) 41, a secondary superheater (2SH; secondary superheater) 42 functioning as a heat exchanger 40, A primary superheater (1SH; primary superheater) 43 is arranged in order from the top. In addition, an economizer (ECO) 44 that functions as a heat exchanger 40 is disposed in the second flue 22 at the rising portion where the product gas folded at the bottom flows upward.

Here, the panel 50 of the heat exchanger 40 described above is a heat transfer tube in which a heat transfer tube 51 such as a carbon steel tube for a boiler heat exchanger, an alloy steel tube, a stainless steel tube or the like for flowing a refrigerant (fluid) exchanges heat with the generated gas. A number of these heat transfer tubes are formed in a substantially U shape and arranged to form a panel 50. Both end portions of each heat transfer tube 51 are connected to the refrigerant inlet portion and the refrigerant outlet portion of the header 52, respectively. Therefore, by arranging this panel 50 in the flue 20, the surface of the heat transfer tube 51 becomes a heat transfer surface, and the refrigerant absorbs heat while circulating in the heat transfer tube 51 from the generated gas flowing in the flue 20. A heat exchanger 40 that cools the product gas and recovers heat from the product gas is configured.
The configuration of each heat exchanger installed in the gasification cooler 300 shown in FIG. 6 is substantially the same as that of the heat exchanger 40 installed in the return flow type gas cooler 10.

<First Embodiment>
For example, as shown in FIG. 1, the heat transfer tube 51 of the heat exchanger 40 described above is provided with a protrusion 60 on the upstream side of the tube surface in the direction of product gas flow.
By making the material of the protrusion 60 better than that of the heat transfer tube 51 or having the same heat transfer property, the thermal resistance between the generated gas and the fluid in the heat transfer tube 51 can be reduced, Recovery efficiency can be improved.
It is preferable that the protrusion 60 has a triangular shape with an angle θ of the upper end portion set to be smaller than the repose angle of dust, which is powder, or a similar shape thereof. That is, if the protrusion 60 has an inclined surface at which the powdered dust slides without staying on the surface of the protrusion 60, even if R (roundness) is formed at the tip corner. Alternatively, it may be a curved surface or an inclined surface that changes its angle in a plurality of stages. However, even when the angle θ at the upper end is larger than the angle of repose of dust, which is powder, the heat resistance between the generated gas and the refrigerant flowing in the heat transfer tube 51 is reduced, so that the heat recovery efficiency It is possible to improve.
In addition, although such a projection part 60 may be provided in all the heat exchanger tubes 51, when the effect and economy are considered, it is provided in the heat exchanger tube 51 which becomes the high dust density | concentration side in the flow direction of product gas. It is preferable.

  Further, the protrusion 60 may be either solid or hollow (for example, a plate is attached in an inverted V shape), but in the case of being hollow, the thermal resistance is increased by the deposit, so that it is preferably solid. The solid protrusion 60 may be formed integrally with the heat transfer tube 51 by drawing or extruding, or may be a member attached separately by welding or the like.

  On the downstream side of the heat transfer tube 51 described above, a negative pressure region is formed on the downstream side of the tube in the flow direction of the product gas. For this reason, a secondary flow is generated from the main flow of the product gas toward the negative pressure region formed on the downstream side of the heat transfer tube 51, and dust is likely to accumulate on the downstream side of the tube to form a stagnation region. As a secondary flow suppressing means for suppressing dust accumulation on the downstream side, a solid covering portion 70 having a substantially rectangular cross-sectional shape is provided so as to cover the downstream side of the pipe surface. The covering portion 70 forms a wall surface that hangs down in the vertical direction substantially coincident with the flow direction of the product gas along the outer diameter D that is the maximum width of the heat transfer tube 51.

  As the covering portion 70 in this case, for example, as shown in FIG. 1, there is a solid member integrated with the heat transfer tube 51. Moreover, as a modification of the covering portion 70 serving as the secondary flow suppressing means, for example, as shown in the first modification shown in FIG. 2A, left and right hanging along the outer diameter D that is the maximum width of the heat transfer tube 51. The pair of plate members 71 or the flow of the generated gas after the heat transfer tube 51, such as a solid covering portion 72 having a substantially triangular cross-sectional shape with an acute angle at the lower end, as in the second modification shown in FIG. Any wall that forms a secondary flow in the basin and does not form a stagnation region may be used.

Either one of the protrusion 60 and the cover 70 described above may be provided alone with respect to the heat transfer tube 51, or both may be provided together.
The heat transfer tube 51 provided with at least one of the protrusion 60 and the cover 70 may have a grid arrangement shown in FIG. 3A or a staggered pattern shown in FIG. 3B. It may be an array.

As described above, in the gasification cooler 300 (FIG. 6) or the return flow type gasification cooler 10 (FIG. 7 or FIG. 9) in which the heat exchanger 40 is configured by the heat transfer tube 51 including the protrusions 60. Since it is possible to reduce the thermal resistance due to the accumulation of dust on the heat transfer tube 51, it is possible to maintain good heat exchange efficiency.
That is, in the state where dust adheres around the heat transfer tube 51, the dust becomes a thermal resistor that hinders heat transfer, so the temperature difference between the temperature of the generated gas and the refrigerant in the heat transfer tube 51 increases. For this reason, although the heat recovery efficiency of the heat exchanger that cools the generated gas with the refrigerant flowing in the heat transfer tube 51 is reduced due to dust adhesion, the provision of the above-described protrusion 60, the covering portion 70, etc. increases the thermal resistance. It is possible to maintain or maintain good heat recovery efficiency.

上式の変数は、一般値として次のように定める。ダストの厚みは１０ｍｍ、管の長さは１ｍとする。式（１）の左辺は総括熱抵抗であり、右辺第一項は管内の対流による熱抵抗（Ｒ₁ ）、右辺第二項は管の熱伝導による熱抵抗（Ｒ₂ ）、右辺第三項は管外の対流による熱抵抗（Ｒ₃ ）、右辺第四項はダストによる熱抵抗（Ｒ₄ ）である。
Ａ_out:管外伝熱面積 [ｍ²] (＝0.0785ｍ²)
Ａ_in:管内伝熱面積 [ｍ²] (＝0.0628ｍ²)
ｄ_i:伝熱管の内径 [ｍ] (＝0.020ｍ)
ｄ_o:伝熱管の外径 [ｍ] (＝0.025ｍ)
Ｒ:熱抵抗 [Ｋ／Ｗ]
α_in:管内熱伝達率 [Ｗ／ｍ²Ｋ] （＝3000Ｗ／ｍ²Ｋ）
α_out:管外熱伝達率 [Ｗ／ｍ²Ｋ] （＝100Ｗ／ｍ²Ｋ）
δ:ダストの厚み [ｍ] （＝０．０１０ｍ）
λ_d:ダストの熱伝導率 [Ｗ／ｍＫ] （＝０．１Ｗ／ｍＫ）
λ_s:伝熱管の熱伝導率 [Ｗ／ｍＫ] （＝４０Ｗ／ｍＫ）
上の値を式（１）に代入して各熱抵抗を求めると、管内の対流による熱抵抗Ｒ₁ ＝０．００５３Ｋ／Ｗ、管の熱伝導による熱抵抗Ｒ₂ ＝０．００５６Ｋ／Ｗ、管外の対流による熱抵抗Ｒ₃ ＝０．１２７Ｋ／Ｗ、ダストによる熱抵抗Ｒ₄ ＝１．２７４Ｋ／Ｗである。このように、総括熱抵抗１．４１２Ｗ／ｍＫのうち約８８％がダストによる熱抵抗であり、ダストの堆積を抑制することが熱回収効率の向上ため有効であることが分かる。 The increase in thermal resistance due to dust adhesion will be described below. The overall thermal resistance is given by equation (1).

The variables in the above equation are defined as general values as follows. The thickness of the dust is 10 mm, and the length of the tube is 1 m. The left side of equation (1) is the overall thermal resistance, the first term on the right side is the thermal resistance (R ₁ ) due to convection in the tube, the second term on the right side is the thermal resistance (R ₂ ) due to heat conduction in the tube, and the third term on the right side Is the thermal resistance (R ₃ ) due to convection outside the tube, and the fourth term on the right side is the thermal resistance (R ₄ ) due to dust.
A _out : Heat transfer area outside the tube [m ² ] (= 0.0785m ² )
A _in : Heat transfer area _{in the} pipe [m ² ] (= 0.0628m ² )
d _i : Inner diameter of heat transfer tube [m] (= 0.020m)
d _o: outer diameter of the heat transfer tube [m] (= 0.025m)
R: Thermal resistance [K / W]
α _in : Heat transfer coefficient _{in the} tube [W / m ² K] (= 3000 W / m ² K)
α _out : Heat transfer coefficient outside the tube [W / m ² K] (= 100 W / m ² K)
δ: Dust thickness [m] (= 0.010m)
λ _d : Thermal conductivity of dust [W / mK] (= 0.1 W / mK)
λ _s : thermal conductivity of heat transfer tube [W / mK] (= 40W / mK)
Substituting the above value into the equation (1) to obtain each thermal resistance, thermal resistance R ₁ = 0.0053 K / W due to convection in the pipe, thermal resistance R ₂ = 0.0056 K / W due to thermal conduction in the pipe, Thermal resistance R ₃ due to convection outside the tube = 0.127 K / W, and thermal resistance R ₄ due to dust = 1.274 K / W. Thus, it can be seen that about 88% of the overall thermal resistance of 1.412 W / mK is the thermal resistance due to dust, and it is effective to suppress the accumulation of dust to improve the heat recovery efficiency.

式（２）において、Ｕ：ガス流速[ｍ／ｓ]、ｄ_o：伝熱管の外径[ｍ]、ｖｇ：ガスの動粘性係数[ｍ² ／ｓ]である。
汚れ係数Ｒ₄ は、式（１）の右辺第四項であり、式（３）で定義される。

図４に示すように、レイノルズ数が大きい、即ちガス流速が高いほど、伝熱管５１に対するダストの熱抵抗を示す汚れ係数が低下するとの知見を得た。このことは、ガス化炉２００で生成され、ガス化冷却器１０，３００内に導入された生成ガスの流速が大きいほど汚れ係数も低下し、伝熱管５１にダストが付着しにくいことを意味している。 As a result of the gasification test, the present inventors have obtained the knowledge that the relationship between the Reynolds number (Re) and the fouling coefficient (R ₄ ) can be arranged in a manner similar to general heat transfer characteristics. .
Here, the Reynolds number Re is defined by the ratio between the inertial force and the viscous force as shown in Equation (2).

In equation (2), U: gas flow velocity [m / s], d _o : outer diameter of heat transfer tube [m], vg: kinematic viscosity coefficient [m ² / s] of gas.
The contamination coefficient R ₄ is the fourth term on the right side of the equation (1) and is defined by the equation (3).

As shown in FIG. 4, it was found that the greater the Reynolds number, that is, the higher the gas flow rate, the lower the fouling coefficient indicating the thermal resistance of dust to the heat transfer tube 51. This means that the greater the flow rate of the product gas generated in the gasification furnace 200 and introduced into the gasification coolers 10 and 300, the lower the fouling coefficient, and the less the dust adheres to the heat transfer tubes 51. ing.

従って、熱交換器４０としての熱回収効率を高効率に維持するためには、生成ガスの流速を上げるだけでは限界があるので、伝熱管５１に上述した突起部６０や被覆部７０を設置することが有効となる。 However, the above-mentioned product gas flow rate has an upper limit due to wear, and therefore there is a limit to reducing the contamination coefficient. That is, the flow rate U _CR of the product gas that enables the reduction of the contamination coefficient is limited by the flow rate corresponding to the Reynolds number Re _CR shown in FIG. 4, and if the product gas is flowed at a higher speed than this, it is transmitted by the collision of dust. Since wear of the heat pipe 51 is promoted, it is not preferable.
Here, the critical Reynolds number Re _CR is defined by equation (4).

Therefore, in order to maintain the heat recovery efficiency as the heat exchanger 40 with high efficiency, there is a limit only by increasing the flow rate of the generated gas. Therefore, the above-described protrusion 60 and the covering part 70 are installed in the heat transfer tube 51. Is effective.

<Second Embodiment>
Subsequently, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part similar to embodiment mentioned above, and the detailed description is abbreviate | omitted.
The gasification cooler 10A shown in FIG. 9 is a return flow type similar to the gasification cooler 10 shown in FIG. The gasification cooler 10A includes an introduction flow path corner portion for introducing a generated gas into the flue 20A, a discharge flow path corner portion for discharging the generated gas from the flue 20A, and a partition that partitions the flow in the flue 20A. A generated gas flow path is provided in which at least one corner portion of the 30A flow direction changing portion is rounded.

  More specifically, the introduction duct flow path corner portion serving as the first flue inlet 25 for introducing the generated gas from the gasification furnace (not shown) into the first flue 21A is rounded and has a secondary flow. Try not to form a stagnation zone. That is, when the flow of the product gas is bent at the corner portion near the first flue inlet 25, a stagnation region due to the secondary flow is formed, near the wall surface on the downstream side of the corner portion where the curvature radius is small. A stagnation area S1 is produced. As a result, a region having a flow velocity higher than the average flow velocity is formed around the first flue inlet 25 at a position distant from the stagnation region S1, as shown by a velocity distribution Vd shown in the drawing. Since the momentum of the dust colliding with the heat transfer tube 51 is large and the wear amount at the time of the collision is large in the high flow velocity region, the wear rate becomes nonuniform according to the dust velocity distribution Vd, and the life of the designed heat exchanger 40 is increased. Cannot be obtained.

However, since the formation of the stagnation region due to the secondary flow described above is prevented or suppressed by giving the first flue inlet 25 an appropriate roundness, the speed difference of the speed distribution Vd can be made uniform. Accordingly, since the velocity distribution of the dust colliding with the heat transfer tube 51 is made uniform, it is possible to obtain the life of the designed heat exchanger 40 by eliminating the non-uniform wear progression according to the velocity distribution Vd.
In this way, the R-shaped roundness is provided in the product gas passage duct to prevent or suppress the formation of the stagnation region due to the secondary flow, in addition to the first flue inlet 25 described above. The stagnation area S2 is formed because it becomes a flow path corner portion near the discharge flow channel outlet 26 that discharges the generated gas from the road 22A toward the char recovery facility, or a flow direction changing portion of the partition wall 30A that partitions the flow in the flue 20A. The same applies to the resulting folded portion 24A.

Such R-shaped roundness flows up-flow from the flow path corner near the first flue inlet 25, the flow path corner near the second flue outlet 26, and the first flue 21A flowing down. Although it is preferable to employ it in the vicinity of the turn-around portion 24A that changes the flow direction to the second flue 22A, it may be applied to only one location. In addition, what is necessary is just to give moderate rounding to the lower end part 31 of the partition 30A for the roundness of R shape of the folding | turning part 24A.
By the way, it is preferable that the radius of curvature of the rounded R-shape described above is approximately 1 / 10D to 2D, based on the inner diameter D of the flow path.
Such rounded R shape is also applicable in the gasification cooler 300 without the folded portion 24A even when there are flow path corner portions near the flue inlet and near the flue outlet.

Further, due to the influence of the formation of the stagnation region due to the secondary flow described above, the heat flow on the high dust concentration side closer to the first flue 21A (evaporator 41A in the example of FIG. 9) has a lower flow rate due to the formation of the stagnation region. Since dust tends to accumulate on the furnace wall 27 side, the planned heat recovery efficiency cannot be obtained due to an increase in thermal resistance due to dust accumulation.
Therefore, by arranging the heat exchangers at the high flow velocity portions in the respective flues on both the first flue 21A side that is the downflow flow and the second flue 22A side that is the upflow flow, Is used as a pressure loss resistor.

  In the example shown in FIG. 9, the evaporator 41A at the entrance of the first flue where the dust concentration of the product gas is the highest is installed at a location where the velocity distribution Vd is larger than the average flow velocity. That is, the evaporator 41A is not disposed in the stagnation region S1 in the vicinity of the furnace wall 27 where the velocity distribution Vd is small due to the formation of the stagnation region by the secondary flow, and this is disposed at an appropriate interval L from the furnace wall 27. Yes. As a result, the evaporator 41A functions as a pressure loss resistor, and the secondary secondary heater and the primary superheater on the downstream side can obtain a uniform speed distribution, that is, a uniform heat load distribution, and a planned life can be obtained. However, when the evaporator 41A is used as the pressure loss resistor, it is necessary to determine the specifications of the heat transfer tube in consideration of the locally high gas flow rate and the higher wear rate than other heat exchangers.

According to the above-described present invention, dust can be prevented or suppressed from accumulating on the heat transfer tubes 51 forming the heat exchanger such as the evaporator 41. Therefore, the gasification cooler 10, Good heat recovery efficiency of 10A, 300 can be maintained.
Moreover, since the nonuniformity of the heat load that reduces the durability of the heat transfer tube 51 forming the heat exchanger such as the evaporator 41 can be eliminated, the heat exchanger and the gas including the heat exchanger as a constituent element can be eliminated. The durability of the chemical cooler 10, 10a, 300 can be improved.

Furthermore, in the first embodiment and the second embodiment described above, the effect of maintaining the heat recovery efficiency and improving the durability become even more remarkable by mutual combination.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

It is a figure which shows 1st Embodiment which concerns on the gasification cooler of this invention, and is sectional drawing which shows the structure of the heat exchanger tube provided with the projection part and the coating | coated part. It is a figure which shows the modification of the coating | coated part shown in FIG. 1, (a) is sectional drawing which shows the board | plate material of a 1st modification, (b) is sectional drawing which shows the substantially triangular cross-sectional shape of a 2nd modification. It is a figure which shows the example of arrangement | positioning of a heat exchanger tube, (a) is an example of grid arrangement, (b) is an example of zigzag arrangement. Is a diagram showing the relationship between the Reynolds number (Re) and dirt coefficient (R _4). It is a schematic block diagram of the coal gasification facility used for a coal gasification combined cycle power plant (IGCC). It is a schematic block diagram of a gasification cooler. It is a schematic block diagram of the gasification cooler made into the return flow type. It is a cross-sectional view of the gasification cooler shown in FIG. It is a schematic block diagram which shows a return flow type gasification cooler as 2nd Embodiment which concerns on the gasification cooler of this invention.

Explanation of symbols

10, 10A, 300 Gasification cooler 51 Heat transfer tube 60 Projection part 70 Cover part (secondary flow suppression means)
71 Plate material (secondary flow suppression means)
72 Solid coating part (secondary flow control means)
20, 20A, 301 Flue 24, 24A Turn-up part 25 First flue inlet 26 Second flue outlet

Claims (3)

A heat exchanger in which a flue through which a product gas introduced from a gasification furnace flows is formed in a pressure vessel, and heat is exchanged between the fluid flowing through a heat transfer pipe installed in the flue and the product gas. ,
A solid triangular section protrusion provided on the upstream side of the heat transfer tube, and a solid and substantially rectangular cross section secondary flow suppression means provided on the downstream side of the heat transfer tube, Heat exchanger. At least one of an introduction flow path corner portion for introducing a high temperature gas into the flue, a discharge flow passage corner portion for discharging a generated gas from the flue, and a flow direction changing portion of a partition wall that partitions a vertical flow in the flue. One is provided with a product gas flow path having a rounded R shape, and the radius of curvature of the rounded R shape is set to 1 / 10D to 2D with reference to the inner diameter D of the flow path. The heat exchanger according to claim 1 . The heat exchanger according to claim 1 or 2, wherein a tube group of the heat transfer tubes is arranged at a high flow velocity portion of the product gas flowing in the flue.

Images