CN1248683A

CN1248683A - Pitch changeable type superheater and reheater

Info

Publication number: CN1248683A
Application number: CN 99113926
Authority: CN
Inventors: 缪正清; 徐通模
Original assignee: Shanghai Jiao Tong University
Current assignee: Shanghai Jiao Tong University
Priority date: 1999-07-29
Filing date: 1999-07-29
Publication date: 2000-03-29
Anticipated expiration: 2019-07-29
Also published as: CN1111667C

Abstract

In the interior of convection pass after outlet of furnace chamber, the distribution header and collecting header of superheater and reheater, axially adopt variable-pitch arranged parallelly-connected tube plates (coils) to make the flue pass section between all the tube plates (coils) progressively increase or progressively decrease along the fume flow direction, and urther controlthe fume flow speed of fume passing through between all the tube plates (coils) to control the heat transmission of fume to all the tube plates (coils), and finally obtain the goal of controlling axial enthalpy value deviation of parallelly-connected tube group outlet vapour along header. Said invention possesses good working effect and application value in boiler field, and raises the operation reliability of the plants of boiler and power generator unit.

Description

Pitch changeable type superheater and reheater

What the present invention relates to is a kind of superheater and reheater, and especially a kind of control parallel transistor group belongs to the field of boilers in the mechanical engineering along the pitch changeable type superheater and the reheater of (the collection case is axial) flue width flue gas flow rate deviation and thermal deviation.

Superheater and reheater are the important component parts of power boiler, and along with modern boiler develops to vast capacity and ultra-high parameter direction, the outlet steam temperature of superheater, reheater has used the resistance to extreme temperature of material near it.Superheater, reheater be by forming with screen multitube circle parallel transistor group, and it is along the flue width or along collecting axially pitch arrangement such as employing always of case.Since along inhomogeneous, the flue gas flow rate of flue width fume side heat load distribution distribute inhomogeneous, the steam side flow distribution is inhomogeneous, pipe group structure inhomogeneous, or four kinds of factors can not be cancelled out each other to the influence that steam enthalpy in the parallel transistor group increases deviation, therefore cause superheater, reheater tube group steam enthalpy to increase deviation, local pipe group generation overtemperature tube burst when serious, and directly influence security, reliability and the economy that equipment moves.Through the retrieval of background technology is recognized that present professional has taked some technical measures at fume side that causes superheater and reheater thermal deviation and steam side, to fume side, be mainly the swirl strength that the quadrangle tangential circle jet forms in the weakening furnace, also have on fire box top the radiation shield deviation certain angle of sheet, constitute so-called flow guiding screen; The technical measures that steam side is adopted have: increase the internal diameter of allocation set case, especially increase and compile the internal diameter that collects case; Adopt the U type collection case connected mode of homonymy turnover; Adopt the connected mode that multiple spot is introduced, multiple spot is drawn the collection case; In flow pipe group bigger than normal, add the throttling pipeloop; The ips of amplified flow pipe group less than normal; Adopt state-of-the-art technology: promptly based on static pressure in each parallel transistor group two ends collection case of control along collection case length invariance principle, and design the interior assignment of traffic of control collection case and compile uniform deflector structure, and employing suitably changes along collection case length based on static pressure in each parallel transistor group two ends collection case of control, make parallel transistor group flow satisfy specific distribution, control parallel transistor group flow demand assigned manifold preflowing device structure and design to offset the inhomogeneous thermal deviation influence that causes of fume side heat load distribution.These technology and design reach and all have significant effect within the specific limits for solving the problem of institute at type, but deficiency is arranged respectively yet, especially in heavy duty boiler, if continue to keep DC burner corner tangential firing mode, then must solve the thermal deviation problem of convection superheater and reheater, and four jiaos arranged in the straight flow combustion mode boiler horizontal flue left and right sides smoke speed deviation even reach more than the twice of mean value, like this, if adopt sparse large-size screen monitors deflection water conservancy diversion in the burner hearth (combustion chamber) merely before convection superheater and the reheater or adopt above-mentioned various technical scheme at steam side, its effect is just limited to, or it is economical inadequately (as in flow pipe group bigger than normal, adding the throttling pipeloop, the Flow-rate adjustment that makes minimizing is to original flow pipe group less than normal, and this can be because of the efficient that reduces generating set that enlarges markedly of parallel transistor group flow resistance to reheater).

The objective of the invention is to overcome deficiency of the prior art and defective, proposed a kind of superheater and reheater, can improve security, reliability and the economy of boiler operatiopn along flue width (or axial) change pitch type along the collection case.

Technical program of the present invention lies in increasing and parallel transistor group structural configuration with the enthalpy of parallel transistor group, flow and the heat transfer relation of fume side is the basis, proposed in the convection pass behind furnace outlet, compiling collection case and reheater allocation set case and reheater at superheater allocation set case and superheater compiles the collection case and axially adopts to switch political loyalty and arrange tube panel in parallel (circle) apart from mode, make the flue gas flow channel cross section between each sheet tube panel (circle) increase gradually or dwindle gradually along the flow of flue gas direction, and then the flue gas flow rate between each tube panel (circle) is controlled the heat transfer of flue gas to each tube panel (circle) by the control flue gas, finally reach control parallel transistor group and export steam along collecting the axial enthalpy deviation of case.Superheater allocation set case and superheater compile collection case and reheater allocation set case and reheater compile on the collection case axial tube panel segmentum intercalaris apart from distribute or flue in superheater, reheater along the distribution of tube panel (circle) pitch on the flow of flue gas direction cross section, can satisfy parallel transistor group outlet working medium and determine according to the distribution of given flue entrance cigarette speed, heat load distribution along the condition of cigarette speed between straight basic even desired each screen of the axial enthalpy of collection case.For example, at superheater, the reheater gas approach cuts and flue-gas temperature (thermic load) is even substantially, and that cigarette speed exists along the flue width is serious when inhomogeneous, be in superheater, the reheater tube group in the high cigarette speed of incoming flow zone, pitch between its upstream tube panel should be got smaller value, and the pitch between the tube panel of downstream should be got higher value; And be in regional superheater, the reheater tube group of the low cigarette speed of incoming flow, and the pitch between its upstream tube panel should be got higher value, and the pitch between the tube panel of downstream should be got smaller value.Like this, make that runner amplifies gradually between the high tube panel of import cigarette speed, cigarette speed reduces gradually; And runner dwindles gradually between the fast low tube panel of import cigarette, and cigarette speed increases gradually, thereby makes the average cigarette speed trend between each tube panel consistent, and it is also evenly approaching to conduct heat.When the inlet cigarette of superheater, reheater speed evenly, when there was serious deviation in population cigarette temperature along the flue width, the design principle of horizontal tube panel (circle) pitch distribution was same as described above in the runner.When enter the mouth cigarette speed and cigarette temperature skewness exist simultaneously, can according to heat transfer condition propose to the fast requirement of cigarette between tube panel (circle), channel cross-section between design tube panel (circle), and determine that in view of the above compiling collection case and reheater allocation set case and reheater at superheater allocation set case and superheater compiles pitch distribution between the pitch distribution between tube panel (circle) on the collection case or flue upstream, downstream tube panel (circle).

The present invention has good work effect and use value in field of boilers, improved equipment reliabilities of operation such as boiler, generating set, has solved the long-term unsolved technical barrier of professional.The present invention also can be widely used in public utilities, petrochemical industry and nuclear power generation field, has very considerable economic.

Below with reference to accompanying drawing the present invention is further described:

Fig. 1 boiler overall structure schematic diagram

Runner density is arranged and is N type (or Z type) schematic diagram between Fig. 2 the present invention screen

Fig. 3 N type (or Z type) A-A schematic cross-section

Runner density is arranged and is M type schematic diagram between Fig. 4 the present invention screen

Fig. 5 M type A-A schematic cross-section

Runner density is arranged and is W type schematic diagram between Fig. 6 the present invention screen

Fig. 7 W type A-A schematic cross-section

Shown in Fig. 1～7, when superheater allocation set case 3 and superheater compile collection case 4 and reheater allocation set case 5 and reheater compile adopt respectively on the collection case 6 switch political loyalty apart from the time, make each flue gas flow channel between tube panel be gradually expanded form or convergent shape is arranged.The present invention increases and parallel transistor group structural configuration with the enthalpy of parallel transistor group, the mobile phase heat transfer relation of fume side is the basis, proposed in the convection pass behind furnace outlet, superheater allocation set case 3 and superheater compile collection case 4 and reheater allocation set case 5 and reheater and compile collection case 6 and axially adopt to switch political loyalty and arrange tube panel in parallel (circle) apart from mode, make the flue gas flow channel cross section between each sheet tube panel (circle) increase gradually or dwindle gradually along the flow of flue gas direction, and then the flue gas flow rate between each tube panel (circle) is controlled the heat transfer of flue gas to each tube panel (circle) by the control flue gas, finally reach control parallel transistor group and export steam along collecting the axial enthalpy deviation of case.Superheater allocation set case 3 and superheater compile that collection case 4 and reheater allocation set case 5 and reheater compile that axial pitch on the collection case 6 distributes or flue in superheater 2 and reheater 1 along the distribution of tube panel (circle) pitch on the flow of flue gas direction cross section, can distribute according to given flue entrance cigarette speed, heat load distribution satisfies parallel transistor group outlet working medium and determines along the condition of cigarette speed between basic evenly desired each screen of horizontal flue width enthalpy.Utilize of the present invention three groups can prove absolutely by change in superheater 2 and reheater 1 flue between each tube panel in parallel (circle) flow area regulate each shield between cigarette speed, and then by the heat transfer of each runner flue gas of control to the both sides tube panel, the enthalpy of eliminating each tube panel in parallel (circle) increases deviation.The present invention compiles collection case 4 and reheater allocation set case 5 and reheater to tube panel in parallel (circle) and superheater allocation set case 3 and superheater and compiles pitch that collection case 6 is connected by switching political loyalty apart from designing, compile collection case 4 and reheater allocation set case 5 and reheater at superheater allocation set case 3 and superheater and compile on the collection case 6, tube panel (circle) is drawn the plane and is compiled collection case 4 and reheater allocation set case 5 and reheater perpendicular to superheater allocation set case 3 and superheater and compile and collect case 6 axis on the same group; First row of superheater 2 and reheater 1 reverses an angle and the transition mutually of (snakelike) tube panel (circle) mid portion plane of living in last comb screen under roof tube.And along the flue width, on flue gas flow direction, each is organized flue overall shape layout and is typical N (or Z), M, W shape and combination shape thereof.

Embodiment one: the flue gas speed of incoming flow compiles collection case 4 and reheater allocation set case 5 and reheater along the low superheater allocation set case 3 of flue width one side height, a side and superheater and compiles on the collection case 6 the tube panel pitch and arrange and the runner pattern before superheater 2 and the reheater 1.As Fig. 2, shown in Figure 3, the tube panel pitch is arranged as on this collection case of realization embodiment one: the pitch on the collection case of flue upstream, and a side close (being positioned at the incoming flow high velocity), the pitch on this side downstream collection case is dredged; Opposite side is dredged (being positioned at the incoming flow low regime), and the pitch of tube panel is close on this side downstream collection case.Promptly passage amplifies gradually along flue gas flow direction between each tube panel (circle) in territory, one lateral areas, high cigarette speed district, and passage dwindles gradually along flue gas flow direction between each tube panel (circle) in territory, one lateral areas, low cigarette speed district.That is runner density layout is N shape (or Z type).

Embodiment two: superheater allocation set case 3 that the flue gas speed of incoming flow is high in the middle of the flue width before superheater 2 and the reheater 1, both sides are low and superheater compile collection case 4 and reheater allocation set case 5 and reheater and compile on the collection case 6 the tube panel pitch and arrange and the runner pattern.As Fig. 4, shown in Figure 5, the tube panel pitch is arranged as on this collection case of realization embodiment two, the pitch of tube panel on the collection case of flue upstream, middle close (being positioned at the incoming flow high velocity), middle part tube panel pitch is dredged on the collection case of downstream; (being positioned at the incoming flow low regime) dredged in both sides, and the pitch of tube panel is close on the respective downstream collection case.Promptly passage amplifies gradually along flue gas flow direction between each tube panel (circle) of flue central region, and passage dwindles gradually along flue gas flow direction between each tube panel (circle) of flue two side areas.That is runner density layout is the M type.

Embodiment three: superheater allocation set case 3 that the flue gas speed of incoming flow is low in the middle of the flue width before superheater 2 and the reheater 1, both sides are high and superheater compile collection case 4 and reheater allocation set case 5 and reheater and compile on the collection case 6 the tube panel pitch and arrange and the runner pattern.As Fig. 6, shown in Figure 7, the tube panel pitch is arranged as on this collection case of realization embodiment three: dredge (being positioned at the incoming flow low regime) on the collection case of flue upstream in the middle of the pitch of tube panel, middle part tube panel pitch is close on the collection case of downstream; Both sides close (being positioned at the incoming flow high velocity), the pitch of tube panel is dredged on the respective downstream collection case.Promptly passage dwindles gradually along flue gas flow direction between each tube panel (circle) of flue central region, and passage amplifies gradually along flue gas flow direction between each tube panel (circle) of flue two side areas.That is runner density layout is W shape.

Claims

1. A variable pitch superheater and reheater, characterized in that in the convection flue behind the furnace outlet, the superheater distribution header 3, the superheater collection header 4, the reheater distribution header 5 and the reheat The collector box 6 is axially arranged in a variable-pitch manner to arrange parallel tube panels (circles), so that the cross-section of the flue gas flow passage between each tube panel (circle) gradually increases or decreases along the direction of flue gas flow, and then through the control The flue gas flow rate between each tube panel (circle) controls the heat transfer of the flue gas to each tube panel (circle), and finally achieves the control of the enthalpy deviation of the outlet steam of the parallel tube group along the axial direction of the header.

2. The variable pitch superheater and reheater according to claim 1, further characterized in that its superheater distribution header 3 and superheater collection tank 4 and reheater distribution header 5 and reheat The distribution of the pitch between the axial tube panels on the collector box 6 or the distribution of the pitch of the tube panels (rings) on the cross-section of the superheater 2 and reheater 1 in the flue along the flue gas flow direction can be based on a given flue inlet The smoke velocity distribution and heat load distribution are determined by satisfying the condition of the smoke velocity between the screens that is basically uniform in the axial enthalpy value of the working fluid at the outlet of the parallel tube group along the header.