RU2266475C1 - Pipe row of regenerative air heater - Google Patents

Abstract

FIELD: power engineering, in particular, devices for utilization of heat of gases exhausted by apparatuses, primarily for heating air by combustion products, coming from compressor of gas-turbine plant of gas flow apparatus at compressor stations of main gas pipelines.

SUBSTANCE: pipe row of regenerative air heater is made four-drive, while length of inner area of pipe in row is selected dependently on geometrical parameters of pipes, composing pipe row, and on step between longitudinal axes of adjacent pipes of rectilinear branches at different portions of rows, while step and length of inner area of heat exchange pipes of minimal and maximal length is selected in proposed range dependently on pipe diameter. Position of heat exchange pipes in row is selected with fulfilling of criterion, in accordance to which relation of area of inner surface of heat exchange pipes on rectilinear branches of row, positioned perpendicularly to flow of substance to be cooled, to volume, contoured by conditional planes, touching external surfaces of heat exchange pipes of row, with consideration of spaces between pipes, is 0,02-0,12 m^-1.

EFFECT: higher heat exchange efficiency during enveloping by high temperature combustion products of one-packet four drive row of heat exchange pipes, filled with air to be heated, due to use of special relations, considering geometrical parameters of pipe row, including those for heat exchange pipes.

8 cl, 4 dwg, 2 tbl, 2 ex

Description

The invention relates to a power system, and in particular, to devices for recovering heat from exhaust gases from aggregates, in particular for heating air with exhaust products from a compressor of a gas turbine installation of a gas pumping unit at compressor stations of gas mains.

A four-way multi-row bundle of heat-exchange tubes of a regenerative air heater is known (RU No. 17600 F 23 L 15/04, 2000), the pipe row of which includes V-shaped tubes with one bend and two straight branches installed in horizontal rows, each row containing two V-shaped tubes located adjacent to each other.

The disadvantage of this device is that it does not provide high heat transfer efficiency and has a high metal consumption.

The closest analogue is a pipe row of a four-way multi-row bundle of heat-exchange tubes of a regenerative air heater (RU No. 31838 F 23 L 15/04, 2002), containing heat-exchange tubes laid in horizontal rows, each heat-exchange tube of a row having four, five or six bends, forming four rectilinear branches and three knees connecting them.

The disadvantages of the closest analogue include the fact that it does not provide high heat transfer efficiency while ensuring compact stacking, as a result of which the design has an increased metal consumption.

The problem solved by the invention is to increase the efficiency of heat transfer and reduce metal consumption.

The tasks are solved due to the fact that the pipe row of the regenerative air heater is made of four-way and is formed by heat exchange pipes bent in the horizontal plane with the formation of four straight branches and three bends connecting them, bends of which are made with radii R, while the bend sections of two pipes in each predominantly odd row has a length πR, namely, one pipe has an inner bend, the other has two external bends, for the remaining pipes of odd and even rows the bend sections are of length πR / 2 and articulated by means of rectilinear inserts of different lengths for the outer and inner bends of the row pipes, while the parameters of each row pipe are defined by

L _{i + 1} = 2l ' _{i + 1} + 2l " _{i + 1} -Δ + 2H' _{i + 1} + H" _{i + 1} + 3πR, where

L _{i + 1} is the scan length of the (i + 1) th row pipe, [m];

l ' _{i + 1} - the length of the outer straight branch (i + 1) of the row pipe equal

l ' _{i + 1} = l' _i -b, [m];

l " _{i + 1} is the length of the inner rectilinear branch (i + 1) of the row pipe equal to l" _{i + 1} = l ' _i -Δ, [m];

H ' _{i + 1} - the length of the rectilinear inserts of the outer elbows of the (i + 1) th pipe of the row, equal to H' _{i + 1} = H ' _i -2a, [m];

H " _{i + 1} is the length of the straight insert of the inner bend of the (i + 1) th pipe of the row, equal to H" _{i + 1} = H " _i + 2a, [m];

and - the step between the longitudinal axes of the same straight branches adjacent in the row of pipes, [m],

b is the step between the longitudinal axes of the rectilinear inserts of the elbows of adjacent pipes in a row, [m];

Δ is an empirical value equal to [3-12] · 10 ^-3 , [m];

l ' _i , l " _i , Н' _i and H" _i are the corresponding parameters for the i pipe in the row, counting from the outer pipe to the inner pipe in this row, and step a is (1.5-2.5) · d, step b is (1.8-2.8) · d, where d is the outer diameter of the heat exchanger pipe, [m], the scan length L _{min of the} heat transfer pipe of the minimum length is at least 0.75 of the scan length L _{max of the} heat transfer pipe of the maximum length.

The step a between the longitudinal axes of the same straight branches of adjacent pipes in a row can be less or greater than the step b between the longitudinal axes of the rectilinear inserts of the elbows of adjacent pipes in a row, preferably a <b, or step a can be equal to step b.

The placement of the pipe heat exchanger in a row can be selected subject to the condition according to which the ratio of the internal surface area of the heat exchange pipes on the straight branches of the row perpendicular to the flow of the cooled medium to the volume occupied by the series of heat transfer pipes and equal to the volume outlined by the conditional planes touching the outer surfaces the heat exchange tubes of the row, taking into account the gaps between the tubes, is 0.02-0.12 [m ^-1 ], and for each heat exchange tube of the row the distance H between the longitudinal axes e e of the external rectilinear branches is (30-85) d; the length of the straight branches l 'and l "may be (74-145) d and (100-135) d, respectively, where d is the outer diameter of the heat exchanger pipe, [m].

The total length l ' _Σ and l " _{Σ of the} rectilinear outer and inner branches of a series of heat transfer tubes located perpendicular to the flow of the cooled medium can be at least 72% of the total length of the sweeps L _{Σ of the} heat transfer tubes of the row, and the total length of the straight inserts H' _Σ and H" _{Σ of} three elbows of the heat exchange tubes of the row, the heated medium in which is located in countercurrent with the cooled medium, can comprise up to 18% of the total length of the sweeps L _{Σ of the} heat exchange tubes of the row.

The pipe row may contain an even number of pipes, preferably not less than two and not more than ten.

The pipe row may contain an odd number of pipes, preferably not less than three and not more than nine.

The pipes can be arranged along with a variable distance between the axes of the external branches, the smallest value of this distance being the pipe whose ends are embedded in the holes closest to each other of the corresponding single-level rows of holes in the pipe boards of the headers for supplying and discharging a heated medium, preferably air, heat exchange regenerative air heater unit, each subsequent four-branch pipe of the row can be made covering the previous one from the outer side of the external branches and the most The largest value of this distance is for the pipe, the ends of which are embedded in the extreme, farthest from each other holes of the corresponding single-level rows of holes in the pipe boards of the headers for supplying and discharging the heated medium.

Two internal branches of each subsequent pipe in a row with a bend connecting them can be inscribed on the outside into a bend formed by the corresponding branches and a bend of a previous pipe connecting them in a pipe row.

The implementation of the pipe series of the block of the regenerative air heater in accordance with the invention allows for high heat transfer efficiency while ensuring a compact structure and reducing metal consumption.

The technical result, which is achieved by using the invention, is to ensure high heat transfer efficiency when high-temperature combustion products flow around a single-pack four-way series of heat-exchange tubes filled with heated air by using the proposed ratios that take into account the geometric parameters of the tube series, including parameters of heat-exchange tubes.

The pipe series for the heat exchanger is characterized by the geometric characteristics of the heat exchange pipes, including the ratio of the internal surface area of the heat exchange pipes of straight branches in the area of active heat transfer to the volume occupied by a number of heat exchange pipes, taking into account the volume occupied by the annular medium, and the ratios characterizing the series heat exchange pipes.

Achieving effective heat transfer with minimal metal consumption is possible with the simultaneous use of the proposed ranges of values of geometric parameters and with the execution of heat transfer tubes in single-package four-way, the ratio of the step between the pipes in different sections of the pipe row to the outer diameter of the pipe should also be maintained in the proposed range.

This embodiment of the pipe series allows, in addition to increasing the efficiency of heat transfer, also reduce the metal structure.

The invention is illustrated by drawings, which depict:

figure 1 is a top view of a heat exchange unit of a regenerative air heater with a pipe row;

figure 2 is a section aa in figure 1;

figure 3 - node B in figure 1;

figure 4 - heat transfer pipe series.

The pipe row 1 of the regenerative air heater is made of four-way and is formed by heat exchange tubes 2, bent in the horizontal plane with the formation of four straight branches 3 and three bends 4 connecting them, bends 5 of which are made with radii R, while bending sections 5 of two pipes 2 in each mainly the odd 6th row 1 has a length πR, namely, one pipe has an inner bend 7, the other has two external bends 8, for the remaining pipes 2 an odd 6 and even 9 rows 1 sections of bend 5 have a length πR / 2 and are joined by P yamolineynyh inserts 10,11, respectively, for different length external 8 and internal pipe elbows 7 2 rows 1, wherein the parameters of each pipe 2 rows 1 are defined dependencies:

L _{i + 1} = 2l ' _{i + 1} + 2l " _{i + 1} - Δ + 2H' _{i + 1} + H" _{i + 1} + 3πR, where

L _{i + 1} - the length of the scan (i +1) of the 2nd pipe 2 rows 1, [m];

l ' _{i + 1} - the length of the outer 12 straight branch of the 3 (i + 1) -th pipe 2 of row 1, equal to l' _{i + 1} = l ' _i -b, [m];

l " _{i + 1} - the length of the inner 13 straight branch of the 3 (i + 1) -th pipe 2 of row 1, equal to l" _{i + 1} = l ' _i -Δ, [m];

H ' _{i + 1} - the length of the rectilinear inserts 10 of the outer elbows of the 8 (i + 1) th pipe 2 of row 1, equal to H' _{i + 1} = H ' _i -2a, [m];

H " _{i + 1} - the length of the straight insert 11 of the inner elbow of the 7 (i + 1) -th pipe 2 of row 1, equal to H" _{i + 1} = H " _i + 2a, [m];

a - step between the longitudinal axes of the same straight branches 12,13 adjacent in a row of 1 pipe 2, [m];

b is the step between the longitudinal axes of the rectilinear inserts 10.11 elbows 8.7 adjacent pipes 2 in row 1, [m];

Δ is an empirical value equal to [3-12] · 10 ^-3 , [m];

l ' _i , l " _i , Н' _i and H" _i are the corresponding parameters for i pipe 2 in row 1, counting from the outer pipe to the inner pipe in this row, and step a is (1.5-2.5) d, step b is (1.8-2.8) · d, where d is the outer diameter of the heat transfer pipe 2, [m], the scan length L _{min of the} heat transfer pipe 2 of the minimum length is at least 0.75 of the scan length L _{max of the} heat transfer 2 pipes of maximum length.

The step a between the longitudinal axes of the straight branches of the same name 12,13 adjacent pipes 2 in row 1 may be less or greater than the step b between the longitudinal axes of the rectilinear inserts 10,11 bends 8,7 adjacent pipes 2 in row 1, preferably a <b, or step a may be equal to step b.

The location of the heat exchange tubes 2 in row 1 is selected subject to the condition according to which the ratio of the internal surface area of the heat exchange tubes 2 on the straight branches 3 of row 1, perpendicular to the flow of the cooled medium, to the volume occupied by row 1 of the heat exchange tubes 2 and equal to the volume outlined by conventional the planes touching the outer surfaces of the heat exchange tubes 2 of the row 1, taking into account the gaps between the pipes 2, is 0.02-0.12 [m ^-1 ]. For each heat exchange tube 2 of row 1, the distance H between the longitudinal axes of its outer straight branches 12 can be (30-85) d; the length of the straight branches 12 and 13, respectively, l 'and l "can be (74-145) d and (100-135) d, respectively, where d is the outer diameter of the heat exchange tube 2, [m].

The total length l ' _Σ and l " _{Σ of the} rectilinear outer 12 and inner 13 branches 3 of the row 1 of the heat exchanger tubes 2 located perpendicular to the flow of the cooled medium can be at least 72% of the total length of the reamers L _{Σ of the} heat exchanger tubes 2 of the row 1, and the total length of the rectilinear inserts 10.11 N ' _Σ and H " _{Σ of} three elbows 4 heat exchange tubes 2 rows 1, the heated medium in which is located in countercurrent with the cooled medium, can make up to 18% of the total length of the reamers L _Σ heat transfer tubes 2 row 1.

The pipe row 1 may contain an even number of pipes 2, preferably not less than two and not more than ten.

The pipe row 1 may contain an odd number of pipes 2, preferably not less than three and not more than nine.

Pipes 2 can be located in row 1 with a variable distance between the axes of the outer branches 12, the smallest value of this distance at the pipe 2, the ends of which are embedded in the closest closest holes of the corresponding single-level rows of holes in the pipe boards of the collectors for supplying and discharging the heated medium, preferably air, heat exchanger block of the regenerative air heater, each subsequent four-branch pipe 2 of row 1 can be made covering the previous one from the outer side of the external branches 12 and the largest value of this distance is at the pipe 2, the ends of which are embedded in the extreme outermost openings of the corresponding single-level rows of holes in the pipe boards of the headers for supplying and discharging the heated medium.

Two internal branches 13 of each subsequent pipe 2 in row 1 with an elbow 7 connecting them can be inscribed externally into a bend formed by the corresponding branches 13 and connecting an elbow 7 of a previous pipe 2 in a pipe row 1.

The combustion products enter the air heater block and wash the heat exchange tubes 2 with heated air. The supply of combustion products to the heat exchange units is countercurrent with the direction of movement of the heated air, that is, the combustion products enter the heat exchange unit from the location of the collector of the outlet of the heated medium. At the entrance to the heat exchange unit, the combustion products have a temperature of 520-550 ° C. Passing through the heat exchange tubes 2, the air is heated by the combustion products to a temperature of 440-450 ° C and through the tube board and the air exhaust manifold enters the furnace inlet of the gas turbine installation. Combustion products are vented to the atmosphere.

The high heat transfer efficiency of the pipe row 1 of the regenerative air heater block, made according to the invention, is determined by the geometric characteristics of the heat exchange tubes 2 selected using the above experimental ratios, taking into account the geometric parameters for the known properties of the heated medium — air and cooled medium — GTU combustion products. Moreover, the invention provides a reduction in the mass and dimensions of the heat exchange units.

Example No. 1

To construct an odd row of a bundle of heat exchange tubes of a regenerative air heater unit according to this invention.

Given: The pipe row is composed of four-branch bent pipes with a diameter of ⌀25 × 1.0 mm. Each pipe contains two external rectilinear branches of length l ', two internal rectilinear branches of each length l ", two external bends, each formed by two bends of radius R at an angle π / 2 and a length πR / 2 and a straight insert of length H', and one inner an elbow formed by two bends of radius R at an angle π / 2 and a length πR / 2 with a straight insert H ". Pipes in a row are arranged with a step a between the axes of the branches of the same name and a step b between the axes of the straight inserts of the same elbows.

The design of the pipe series is carried out from the condition of the most dense pipe packing in the block.

The dimensions of the internal volume of the block in the plan for placing the rows of heat-exchange tubes forming a bundle are 3130 × 1650 mm. Based on this, we set the dimensions of the pipe elements No. 1 l ' ₁ = 3060 mm, l " ₁ = 2639.5 mm, H' ₁ = 480 mm, h" ₁ = 0 mm. The pitch between the axes of the pipe branches of the same name in the row a = 48 mm; step between the axes of the knees b = 48 mm; bending radius R = 100 mm.

The parameters of the remaining pipes of the series are determined by the dependencies given in the invention.

The results are shown in Table 1.

Table 1 i N ' ₁ , mm N " _i , mm l ' _i , mm l " _i , mm L _i mm 1 480 0 3060 2639.5 13301.5 2 384 96 3012 2645.5 13121.5 3 288 192 2964 2651.5 12941.5 4 192 288 2916 2657.5 12761.5 5 96 384 2868 2663.5 12581.5 6 0 480 2820 2669.5 12401.5,

Example No. 2

To construct an even row of the heat exchange tube bundle of the regenerative air heater unit of the present invention.

Given: The pipe row is composed of four-branch bent pipes with a diameter of 25 × 1.0 mm. Each pipe contains two external rectilinear branches of length l ', two internal rectilinear branches, each of length l ", two external elbows, each formed by two bends of radius R at an angle π / 2 and a length πR / 2 and a rectilinear insert of length H', and one inner bend formed by two bends of radius R at an angle π / 2 and a length πR / 2 with a straight insert H ". Pipes in a row are arranged with a step a between the axes of the branches of the same name and a step b between the axes of the straight inserts of the same elbows.

The design of the pipe series is carried out from the condition of the most dense pipe packing in the block.

The dimensions of the internal volume of the block in the plan for placing the rows of heat-exchange tubes forming a bundle are 3130 × 1650 mm. Based on this, we set the dimensions of the pipe elements No. 1 l ' ₁ = 3036 m, l " ₁ = 2642.5 m, H' ₁ = 432, H" ₁ = 48 m. The pitch between the axes of the pipe branches of the same name in the row a = 48 mm ; step between the axes of the knees b = 48 mm; bending radius R = 100 mm.

The parameters of the remaining pipes of the series are determined by the dependencies given in the invention.

The results are shown in Table 2.

table 2 i N ' _i , mm H " _i mm l ' _i , mm l " _i , mm L _i mm 1 432 48 3036 2642.5 13211.5 2 336 144 2988 2648.5 13031.5 3 240 240 2940 2654.5 12851.5 4 144 336 2892 2660.5 12671.5 5 48 432 2844 2666.5 12491.5

Claims (8)

1. The pipe row of a regenerative air heater, characterized in that it is made of four-way and formed by heat exchange pipes, bent in the horizontal plane with the formation of four straight branches and three bends connecting them, bends of which are made with radii R, while the bend sections of two pipes in each are mainly the odd row have a length πR, namely: one pipe has an inner bend, the other has two outer bends, for the remaining tubes of odd and even rows, the bend sections are πR / 2 and articulated osredstvom rectilinear inserts of different length for the outer and inner tubes knee series, the parameters of each tube row defined dependencies L _{i + 1} = 2l ' _{i + 1} + 2l " _{i + 1} -Δ + 2H' _{i + 1} + H" _{i + 1} + 3πR, where L _{i + 1} is the scan length of the (i + 1) th row pipe, [m]; l ' _{i + 1} is the length of the external straight branch (i + 1) of the row pipe equal to l' _{i + 1} = l ' _i -b, [m]; 1 " _{i + 1} is the length of the internal straight branch (i + 1) of the row pipe equal to l" _{i + 1} , = l ' _i -Δ, [m]; H ' _{i + 1} - the length of the rectilinear inserts of the outer elbows of the (i + 1) th pipe of the row, equal to H' _{i + 1} = H ' ₁ -2a, [m]; N " _{i + 1} is the length of the straight insert of the inner bend of the (i + 1) th pipe of the row, equal to N" _{i + 1} = N " _i + 2a, [m]; a - step between the longitudinal axes of the same straight branches of the same adjacent in a row of pipes, [m]; b is the step between the longitudinal axes of the rectilinear inserts of the elbows of adjacent pipes in a row, [m]; Δ is an empirical value equal to [3-12] · 10 ^-3 , [m]; l ' _i , l " _i , Н' _i and Н" _i are the corresponding parameters for the i-th pipe in the row, counting from the outer pipe to the inner one in this row, and the step a is (1.5-2.5) × d, step b is (1.8-2.8) · d, where d is the outer diameter of the heat exchange pipe, [m], the scan length L _{min of the} heat transfer pipe of the minimum length is at least 0.75 of the scan length L _{max of the} heat transfer pipe maximum length. 2. The pipe row of the regenerative air heater according to claim 1, characterized in that the step a between the longitudinal axes of the same straight branches of adjacent pipes in the row is less than or greater than the step b between the longitudinal axes of the rectilinear inserts of the elbows of adjacent pipes in a row, preferably a <b or step a is equal to step b. 3. The pipe row of the regenerative air heater according to claim 1, characterized in that the placement of the heat exchange pipes in the row is selected subject to the condition according to which the ratio of the internal surface area of the heat transfer pipes on the straight branches of the row, perpendicular to the flow of the cooled medium, to the volume occupied by the number of heat exchange pipes and equal to the volume outlined by the conditional planes touching the outer surfaces of the heat exchange tubes of the row, taking into account the gaps between the pipes, is 0.02-0.12 [m ^-1 ], and for for each heat exchange tube of a series, the distance H between the longitudinal axes of its external straight branches is (30-85) d; the length of the straight branches l 'and l "is (74-145) d and (100-135) d, respectively, where d is the outer diameter of the heat exchanger pipe, [m]. 4. The pipe row of the regenerative air heater according to claim 1, characterized in that the total length l ' _Σ and l " _{Σ of the} rectilinear external and internal branches of a number of heat exchange pipes located perpendicular to the flow of the cooled medium is at least 72% of the total length of the sweeps L _Σ heat exchange tubes of the row, and the total length of the straight inserts H ' _Σ and H " _{Σ of the} three elbows of the heat exchange tubes of the row, the heated medium in which is located in countercurrent with the cooled medium, makes up to 18% of the total length of the sweeps L _{Σ of the} heat exchange tubes but. 5. The pipe row of the regenerative air heater according to claim 1, characterized in that it contains an even number of pipes, preferably not less than two and not more than ten. 6. The pipe series of the regenerative air heater according to claim 1, characterized in that it contains an odd number of pipes, preferably not less than three and not more than nine. 7. The pipe row of the regenerative air heater according to claim 1, characterized in that the pipes are arranged in a row with a variable distance between the axes of the external branches, the smallest value of this distance is the pipe whose ends are sealed in the extreme closest to each other holes of the corresponding sibling rows of holes in pipe boards of manifolds for supplying and discharging a heated medium, preferably air, a heat exchange unit of a regenerative air heater, and each subsequent four-branch pipe of a row has a coverage vayuschey previous to the outer side of the outer legs, and the highest value of this distance in the pipe, the ends of which are embedded in the most extreme we spaced apart openings corresponding single-level rows of holes in tube plates of collectors for supplying and discharging the heated medium. 8. The pipe row of the regenerative air heater according to claim 7, characterized in that the two internal branches of each subsequent pipe in a row with the elbow connecting them are inscribed on the outside in a bend formed by the corresponding branches and the elbow of the previous pipe connecting them in the pipe row.

Images