A split compartment guide plate structure for a waste heat boiler expanded flue

Abstract

The present invention discloses a split-bin type guide plate structure for an expanded flue of a waste heat boiler, comprising a plurality of circular tubes, a plurality of first connecting pieces and a plurality of second connecting pieces, wherein one circular tube corresponds to one first connecting piece and one second connecting piece, one end of the circular tube is connected to the inner wall on one side of the flue through the corresponding first connecting piece, and the other end of the circular tube is connected to the inner wall on the other side of the flue through the corresponding second connecting piece, and a plurality of rib plates are fixed between two adjacent circular tubes. The structure can adapt to the characteristics of high temperature, high flow rate, high pressure and rotation of flue gas at a gas turbine outlet and the heat-insulating structure in the expanded flue, so as to ensure the stable, efficient, economical and reliable operation of the SCR denitrification system.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR denitration of a gas-steam combined cycle unit, and relates to a split-bin type guide plate structure for an expanded flue of a waste heat boiler. Background Art

[0002] Gas-steam combined cycle power generation technology has been widely used in my country due to its clean and efficient characteristics. Usually, the NOx emission concentration at the outlet of the gas turbine can be controlled at 50mg / m 3 (Standard state, dry basis, 15%O 2 In recent years, with the improvement of national environmental protection standards, many regions have put forward more stringent requirements for NOx emissions from gas turbines. For example, Beijing issued the local standard DB11 / 847-2011 (Stationary Gas Turbine Air Pollutant Emission Standard) in 2011, requiring NOx emissions to be less than 30mg / m 3 The Shenzhen Municipal People's Government issued the document No. 1

[2017] "Shenzhen Air Quality Improvement Plan (2017-2020)" requiring that the NOx emission concentration of newly built gas-fired generators be controlled at 15mg / m 3 Before 2020, the NOx emission concentration of E-class gas generator sets will be controlled at 25mg / m 3 Below, the NOx emission concentration of F-class gas generator sets is controlled at 15mg / m 3 In this case, it is difficult to meet the NOx emission requirements by relying solely on the low-nitrogen combustion technology of the gas turbine. Placing a catalyst in the waste heat boiler and using SCR denitrification technology becomes a feasible solution.

[0003] In SCR denitrification technology, the flue gas flow field index is an important factor affecting the performance of the denitrification system. For the gas-steam combined cycle SCR denitrification technology, the cross-section of the gas turbine exhaust flue is relatively small, while the cross-section size of the waste heat boiler at the rear is relatively large. For example, for a 9F-class gas turbine, the diameter of the gas turbine exhaust flue is 6.3m, while the cross-section width and height of the waste heat boiler at the rear are 10m and 20m, respectively. There is usually an expanded flue between the gas turbine outlet flue and the waste heat boiler, but due to the limitation of the site space, the length of the expanded flue cannot be set too long. Therefore, the flue gas velocity distribution uniformity on the cross-section of the waste heat boiler is poor. The catalyst used in SCR denitrification has high requirements for the velocity uniformity and the uniformity of the ammonia nitrogen molar ratio on the inlet cross-section. Unqualified flue gas flow field will cause the ammonia escape of the denitrification system to increase, and increase the operating cost; in some units with a denitrification efficiency requirement of more than 90%, it is even impossible to stably meet the standard. Therefore, it is a better solution to add a guide device to the expanded flue to improve the uniformity of the flue gas flow field distribution on the cross-section of the waste heat boiler. However, adding a guide device to the expanded flue of the waste heat boiler faces the following difficulties: (1) The flue gas velocity, temperature and positive pressure of the exhaust gas from the gas turbine are relatively high; (2) The waste heat boiler and the expanded flue are internally insulated. For large gas turbines, the expanded flue is relatively large in size. When using conventional guide plates, the pressure difference between the windward and leeward sides of the guide plates is relatively large, and the guide plates are subjected to relatively high pressure;

[0004] On the other hand, the thermal insulation structure in the flue puts forward higher requirements on the support structure of the guide plate. Not only the strength requirements of the support structure need to be considered, but also factors such as thermal expansion. In addition, the flue gas at the outlet of the gas turbine also has a certain swirl intensity, and the design of the guide plate also needs to consider the influence of vibration.

[0005] Therefore, in order to make the SCR denitration system of the gas-steam combined cycle unit operate stably, efficiently, economically and reliably, it is necessary to design a guide plate structure suitable for the expanded flue at the inlet of the waste heat boiler. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a split-chamber guide plate structure for a waste heat boiler expanded flue, which can adapt to the characteristics of high temperature, high flow velocity, high pressure and rotation of the gas turbine outlet flue gas and the insulation structure in the expanded flue, thereby ensuring the stable, efficient, economical and reliable operation of the SCR denitrification system.

[0007] To achieve the above-mentioned purpose, the split-bin type guide plate structure for the expanded flue of a waste heat boiler described in the present invention comprises a plurality of circular tubes, a plurality of first connecting members and a plurality of second connecting members, wherein one circular tube corresponds to one first connecting member and one second connecting member, one end of the circular tube is connected to the inner wall on one side of the flue through the corresponding first connecting member, and the other end of the circular tube is connected to the inner wall on the other side of the flue through the corresponding second connecting member, and a plurality of rib plates are fixed between two adjacent circular tubes;

[0008] Two adjacent circular tubes and two adjacent rib plates therebetween form a hollow structure, and steel plates are arranged at both ends of the hollow structure to form a cabin.

[0009] The first connecting member and the second connecting member both include a first support, a connecting steel plate and a second support, wherein the first support is fixed on the inner wall of the flue, the connecting steel plate is fixed on the first support, the second support is fixed on the connecting steel plate, the second support is provided with a through hole, the round tube is inserted into the through hole, and the insertion depth of the round tube is less than the length of the through hole.

[0010] A plurality of notches are formed on the first support in the circumferential direction.

[0011] The distance between the round tube and the corresponding connecting steel plate in the first connecting member is equal to the distance between the round tube and the corresponding connecting steel plate in the second connecting member.

[0012] The number of round tubes is two.

[0013] There are three circular tubes, and the axes of the three circular tubes are not in the same plane.

[0014] The inner diameter of the through hole in the second support upstream of the smoke is 6mm-8mm larger than the outer diameter of the circular tube upstream of the smoke, and the cross section of the through hole in the second support downstream of the smoke is an elliptical structure.

[0015] The three circular tubes are arranged in sequence along the direction of smoke flow, and the inner diameter of the through hole in the second support connected to the middle circular tube is 6mm-8mm larger than the outer diameter of the middle circular tube; the cross-section of the through hole in the second support connected to the circular tubes on both sides is an elliptical structure.

[0016] The present invention has the following beneficial effects:

[0017] The split compartment guide plate structure for the expanded flue of a waste heat boiler described in the present invention is divided into a number of independent compartments by the rib plates during specific operation to strengthen the strength of the guide plate, improve the pressure-bearing capacity of the guide plate, ensure the normal and stable operation of the guide plate inside the expanded flue, meet the flow field indicators of the SCR denitrification system to meet the design requirements, adapt to the characteristics of high temperature, high flow velocity, high pressure and rotation of the flue gas at the gas turbine outlet and the insulation structure in the expanded flue, and ensure the stable, efficient, economical and reliable operation of the SCR denitrification system.

[0018] Furthermore, sufficient expansion space is reserved between the circular tube and the through hole to ensure that the guide plate inside the expanded flue will not be deformed or stressed due to thermal expansion.

[0019] Furthermore, a plurality of notches are provided on the circumferential edge of the first support to reduce the heat transfer of the high-temperature flue gas inside the flue to the outer wall of the flue, reduce the temperature of the outer wall of the expanded flue, and ensure the safety of the boiler's external structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention when the number of the circular tubes 2 is 2;

[0021] Figure 2 for Figure 1 Cross-section view along the AA direction;

[0022] Figure 3 This is a schematic diagram of the structure of the present invention when the number of the circular tubes 2 is 3;

[0023] Figure 4 for Figure 3 Cross-section along the BB direction;

[0024] Figure 5 is a schematic structural diagram of the first support 4;

[0025] Figure 6 for Figure 5 Cross-sectional view in the CC direction;

[0026] Figure 7 It is a schematic diagram of the structure of the second support 6 upstream of the flue gas;

[0027] Figure 8 for Figure 7 Cross-section along the mid-DD direction;

[0028] Fig. 9 It is a structural schematic diagram of the second support 6 downstream of the flue gas;

[0029] Fig.10 for Fig. 9 Cross-sectional view along the EE direction.

[0030] Among them, 1 is a steel plate, 2 is a round tube, 3 is a rib plate, 4 is a first support, 5 is a connecting steel plate, 6 is a second support, 7 is a notch, 81 is a first connecting piece, and 82 is a second connecting piece. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0032] refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 The split-chamber guide plate structure for the expanded flue of a waste heat boiler described in the present invention comprises a plurality of circular tubes 2, a plurality of first connecting members 81 and a plurality of second connecting members 82, wherein one circular tube 2 corresponds to one first connecting member 81 and one second connecting member 82, one end of the circular tube 2 is connected to the inner wall on one side of the flue through the corresponding first connecting member 81, and the other end of the circular tube 2 is connected to the inner wall on the other side of the flue through the corresponding second connecting member 82, and a plurality of ribs 3 are fixed between two adjacent circular tubes 2; two adjacent circular tubes 2 and two adjacent ribs 3 therebetween form a hollow structure, and steel plates 1 are provided at both ends of the hollow structure to form a compartment.

[0033] refer to Figures 5 to 10 The first connecting member 81 and the second connecting member 82 both include a first support 4, a connecting steel plate 5 and a second support 6, wherein the first support 4 is fixed on the inner wall of the flue, the connecting steel plate 5 is fixed on the first support 4, the second support 6 is fixed on the connecting steel plate 5, the second support 6 is provided with a through hole, the round tube 2 is inserted into the through hole, the insertion depth of the round tube 2 is less than the length of the through hole, a plurality of notches 7 are provided on the first support 4 along the circumferential direction, and the spacing between the round tube 2 and the corresponding connecting steel plate 5 in the first connecting member 81 is equal to the distance between the round tube 2 and the corresponding connecting steel plate 5 in the second connecting member 82.

[0034] A number of ribs 3 are arranged between adjacent circular tubes 2, and the diameter and thickness of the two circular tubes 2 can be adjusted as needed to withstand the high pressure generated by the high-speed airflow. Coupled with a reasonable support structure design, the uniformity of velocity distribution on the cross section of the waste heat boiler can be improved while ensuring safe and reliable operation.

[0035] Embodiment 1

[0036] refer to Figure 1 and Figure 2 The number of the circular tubes 2 is two, the inner diameter of the through hole in the second support 6 upstream of the flue gas is 6mm-8mm larger than the outer diameter of the circular tube 2 upstream of the flue gas, the cross-section of the through hole in the second support 6 downstream of the flue gas is an elliptical structure, and the guide plate structure is a flat plate structure.

[0037] Embodiment 2

[0038] Refer to Figure 3 and Figure 4 There are three circular tubes 2, and the axes of the three circular tubes 2 are not in the same plane. The three circular tubes 2 are arranged in sequence along the direction of smoke flow. The guide plate structure is a bent structure, and the inner diameter of the through hole in the second support 6 connected to the middle circular tube 2 is 6mm-8mm larger than the outer diameter of the middle circular tube 2; the cross-section of the through hole in the second support 6 connected to the circular tubes 2 on both sides is an elliptical structure.

[0039] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the scope of protection of the invention.

Claims

1. A split compartment type guide plate structure for a waste heat boiler expanded flue, characterized in that: The invention comprises a plurality of circular tubes (2), a plurality of first connecting pieces (81) and a plurality of second connecting pieces (82), wherein one circular tube (2) corresponds to one first connecting piece (81) and one second connecting piece (82), one end of the circular tube (2) is connected to the inner wall of one side of the flue through the corresponding first connecting piece (81), and the other end of the circular tube (2) is connected to the inner wall of the other side of the flue through the corresponding second connecting piece (82), and a plurality of rib plates (3) are fixed between two adjacent circular tubes (2); Two adjacent circular tubes (2) and two adjacent rib plates (3) therebetween form a hollow structure, and steel plates (1) are provided at both ends of the hollow structure to form a cabin; The first connecting member (81) and the second connecting member (82) both comprise a first support (4), a connecting steel plate (5) and a second support (6), wherein the first support (4) is fixed to the inner wall of the flue, the connecting steel plate (5) is fixed to the first support (4), the second support (6) is fixed to the connecting steel plate (5), the second support (6) is provided with a through hole, the round tube (2) is inserted into the through hole, and the insertion depth of the round tube (2) is less than the length of the through hole; A plurality of notches (7) are formed on the upper circumference of the first support (4); The distance between the circular tube (2) and the connecting steel plate (5) in the corresponding first connecting member (81) is equal to the distance between the circular tube (2) and the connecting steel plate (5) in the corresponding second connecting member (82); The number of the circular tubes (2) is three, and the axes of the three circular tubes (2) are not in the same plane; The three circular tubes (2) are arranged in sequence along the direction of smoke flow, and the inner diameter of the through hole in the second support (6) connected to the middle circular tube (2) is 6 mm to 8 mm larger than the outer diameter of the middle circular tube (2); the cross section of the through hole in the second support (6) connected to the circular tubes (2) on both sides is an elliptical structure.

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