A unit capable of suppressing overheating of boiler reheater

Abstract

The present invention relates to a unit capable of suppressing overheating of a boiler reheater. The unit comprises a boiler, a first cylinder and a second cylinder which are connected in sequence. The gas pressure of the first cylinder is greater than that of the second cylinder. The first reheater and the second reheater which are connected in sequence are arranged in the flue of the boiler. The unit also comprises a reheat overtemperature suppression device which is arranged outside the flue of the boiler. The device comprises a shell with an inlet and an outlet, and a heat exchange tube arranged in the shell. One end of the heat exchange tube is connected to the heat exchange medium outlet of the first reheater, and the other end is connected to the heat exchange medium inlet of the second reheater. The shell inlet is connected to the air outlet of the first cylinder, and the shell outlet is connected to the air inlet of the second cylinder. The present invention solves the problem of overheating of the reheater, improves the efficiency of the boiler and the cylinder, and the system can be traced back to the original design state. The reheat steam temperature can still reach the rated value under pure condensation conditions, and the input of reheater cooling water can be reduced or even eliminated, thereby improving the economy of the unit and reducing the heat consumption rate.

Description

Technical Field

[0001] The invention belongs to the field of thermal power generating sets, and in particular relates to a set capable of suppressing overtemperature of a boiler reheater. Background Art

[0002] At present, the global society is facing serious energy crises and environmental pollution problems, forcing people to strengthen the transformation of existing energy-consuming systems while developing new energy-saving technologies, so as to achieve cost reduction and efficiency improvement, and strive to achieve carbon peak and carbon neutrality. In recent years, with the transformation and upgrading of domestic industry and the improvement of industrial manufacturing capacity, the demand for industrial steam has increased year by year, and the operating conditions of coal-fired power units that have undergone industrial steam supply transformation have been greatly improved. Therefore, industrial steam supply transformation is also an important direction for energy conservation and consumption reduction of coal-fired power units.

[0003] However, in the process of industrial steam supply transformation, reheat units often encounter the phenomenon of reheater overheating due to the mismatch between the main steam and reheat steam flow. The main reason for this problem is that after the steam extraction for heating, the balance between the original boiler pipeline layout and the heat absorption layout is broken. Less reheat cold steam enters the reheater, while relatively more hot flue gas enters the horizontal flue of the reheater, resulting in reheat overheating. In some units with more serious conditions, the momentum of reheater overheating cannot be suppressed even if all the emergency water spray (reheating desuperheating water) is put into use.

[0004] Therefore, with the increase in industrial steam flow, reheater overheating is a difficult problem that many units must solve. At present, most coal-fired power units reduce the reheater temperature by reducing the boiler reheater area, but this method requires construction of the heating surface of the boiler body, which takes a long time and has an adverse effect on boiler efficiency. In addition, when the heat supply decreases (or pure condensing conditions), the reheat steam temperature cannot reach the rated value, etc. There are many unfavorable factors. Some units obtain the ability to extract steam from the reheater to heat by modifying the flow of the turbine, but this method requires a large investment.

[0005] In addition to the above two approaches, there are currently no other options for solving the problem of reheater overheating. Some combustion adjustment methods can only slightly alleviate the overheating phenomenon, but cannot solve the fundamental problem of mismatch of the reheater heating surface after steam extraction for heating.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a unit capable of suppressing overheating of a boiler reheater, avoiding modification of the heating area of ​​the reheater, and ensuring that the reheater can normally reach the rated output temperature.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A unit capable of suppressing overheating of a boiler reheater, the unit comprising a boiler, a first cylinder, and a second cylinder, the boiler being connected to an air inlet of the first cylinder, the air outlet of the first cylinder being connected to an air inlet of the second cylinder, the air pressure of the first cylinder being greater than the air pressure of the second cylinder, a reheater being arranged in a flue of the boiler, the reheater comprising a first reheater and a second reheater, a heat exchange medium outlet of the first reheater being connected to a heat exchange medium inlet of the second reheater, the unit further comprising a reheat overtemperature suppression device, the reheat overtemperature suppression device being arranged outside the flue of the boiler, the reheat overtemperature suppression device comprising a shell and a heat exchange tube, the heat exchange tube being arranged in the shell, one end of the heat exchange tube being connected to the heat exchange medium outlet of the first reheater, and the other end being connected to the heat exchange medium inlet of the second reheater, the shell having an inlet and an outlet, the inlet of the shell being connected to the air outlet of the first cylinder, and the outlet of the shell being connected to the air inlet of the second cylinder.

[0010] Preferably, the reheat overtemperature suppression device further includes a temperature reducing component, which is used to reduce the steam temperature at the outlet of the shell, and the temperature reducing component is connected to a pipeline between the outlet of the shell and the air intake of the second cylinder.

[0011] Further preferably, the cooling component includes a condenser and a cooling water pipeline, and the condenser is connected to the pipeline between the outlet of the shell and the air inlet of the second cylinder through the cooling water pipeline.

[0012] More preferably, the condenser is connected to the air outlet of the second cylinder, and the condenser is used to condense the exhaust gas of the second cylinder into condensed water, and then transport the condensed water to the outlet of the shell through the cooling water pipe.

[0013] Still further preferably, the cooling water pipeline is provided with a water pump and a cooling water flow valve.

[0014] Preferably, the heat exchange tube has a plurality of bent sections and / or spiral sections.

[0015] Preferably, the number of the reheaters is at least three, and one reheat over-temperature suppression device is provided between two of the reheaters or the reheat over-temperature suppression device is not provided.

[0016] Preferably, a first flow valve is provided between the heat exchange medium outlet of the first reheater and the heat exchange medium inlet of the second reheater, and a second flow valve is provided between the heat exchange medium outlet of the first reheater and one end of the heat exchange tube.

[0017] Preferably, a third flow valve is provided between the air outlet of the first cylinder and the air inlet of the second cylinder, and a fourth flow valve is provided between the air outlet of the first cylinder and the inlet of the housing.

[0018] Preferably, the unit further includes a third cylinder, an air inlet and an air outlet of the third cylinder are both connected to the boiler, and the air pressure of the third cylinder is greater than the air pressure of the first cylinder.

[0019] Further preferably, the unit also includes a steam ejector, the ejector pipe of the steam ejector is connected to the air inlet of the third cylinder and the pipeline between the boiler, the exhaust pipe of the steam ejector is connected to at least one of the first cylinder, the second cylinder and the third cylinder, and the outlet pipe of the steam ejector is connected to the inlet of the shell.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0021] The present invention solves the problem of overheating of the boiler reheater, increases the heat absorption of the boiler, and improves the boiler efficiency; the structure for suppressing the overheating of the reheater can participate in the operation of the unit cylinder, thereby improving the cylinder efficiency; at the same time, the heating surface of the reheater is not modified, and the system can still be traced back to the original design state, and the reheat steam temperature can still reach the rated value under pure condensing conditions; the investment in reheater cooling water can be reduced or even eliminated, thereby improving the economy of the unit and reducing the heat consumption rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 This is a schematic diagram of the structure of the reheat over-temperature suppression device and the reheater in this embodiment;

[0023] Attached Figure 2 It is a schematic diagram of the structure of the reheat over-temperature suppression device and the cylinder in this embodiment.

[0024] In the above drawings: 1, boiler; 21, first cylinder; 22, second cylinder; 23, third cylinder; 31, first reheater; 32, second reheater; 4, reheat over-temperature suppression device, device; 41, shell; 42, heat exchange tube; 51, condenser; 52, cooling water pipeline; 53, water pump; 54, cooling water flow valve; 61, first flow valve; 62, second flow valve; 63, third flow valve; 64, fourth flow valve. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] like Figure 1 , 2 As shown, a unit capable of suppressing overheating of a boiler reheater comprises a boiler 1, a first cylinder 21, a second cylinder 22, and a third cylinder 23. The boiler 1 is connected to the air inlet of the first cylinder 21, the air outlet of the first cylinder 21 is connected to the air inlet of the second cylinder 22, the air outlet of the second cylinder 22 exhausts air, the air inlet and the air outlet of the third cylinder 23 are both connected to the boiler 1, the air pressure of the third cylinder 23 is greater than the air pressure of the first cylinder 21, and the air pressure of the second cylinder 22 is greater than the air pressure of the second cylinder 22, that is, the third cylinder 23 is a high-pressure cylinder, the first cylinder 21 is a medium-pressure cylinder, and the second cylinder 22 is a low-pressure cylinder. A reheater is arranged in the flue of the boiler 1, and the reheater is usually designed with multiple headers or sections, and the reheater comprises a first reheater 31 and a second reheater 32, and the first reheater 31 and the second reheater 32 are different headers or sections. The heat exchange medium outlet of the first reheater 31 is connected to the heat exchange medium inlet of the second reheater 32, that is, the flue gas first flows through the first reheater 31 and then flows through the second reheater 32. If the reheat flow rate share decreases, it is easy to cause the reheater to overheat. The unit also includes a reheat overtemperature suppression device 4 to prevent the reheater from overheating. The reheat overtemperature suppression device 4 is arranged outside the flue of the boiler 1 to reduce the modification cost. The reheater can be returned to the original design state without modifying the heating surface of the reheater.

[0029] The reheat overtemperature suppression device 4 includes a shell 41 and a heat exchange tube 42. The shell 41 has an inlet and an outlet. The inlet of the shell 41 is connected to low-temperature steam, and the outlet of the shell 41 outputs high-temperature steam and can be added to the unit to participate in the cycle. The heat exchange tube 42 is arranged in the shell 41. One end of the heat exchange tube 42 is connected to the heat exchange medium outlet of the first reheater 31, and the other end is connected to the heat exchange medium inlet of the second reheater 32. After the low-temperature steam passes through the device 4, the temperature is increased; after the high-temperature reheat steam passes through the device 4, the temperature drops, thereby ensuring the safe operation of the reheater. Specifically, the inlet of the shell 41 is connected to the air outlet of the first cylinder 21, and the outlet of the shell 41 is connected to the air inlet of the second cylinder 22. The temperature deviation between the exhaust gas of the intermediate pressure cylinder and the cold reheat steam is generally between 0-50°C, which is relatively close. The low-temperature steam entering the shell 41 is used to cool the reheat steam. The high-temperature steam after heating enters the low-pressure cylinder, which relatively improves the initial parameters of the low-pressure cylinder, which is conducive to improving the efficiency and output of the low-pressure cylinder. In order to improve the heat exchange effect, the heat exchange tube 42 has multiple bending sections or multiple spiral sections or a combination of bending sections and spiral sections, which extends the heat exchange area and makes the reheater cool down more thoroughly.

[0030] In order to prevent the steam temperature entering the air inlet of the second cylinder 22 from being too high, the device 4 also includes a cooling component, which is used to reduce the steam temperature at the outlet of the shell 41 so that the high-temperature steam output by the device 4 is adjusted to the air inlet range allowed by the second cylinder 22. The cooling component is connected to the pipeline between the outlet of the shell 41 and the air inlet of the second cylinder 22, and a cooling medium can be added to the high-temperature steam output by the shell 41 before entering the second cylinder 22. The cooling component includes a condenser 51 and a cooling water pipeline 52. The condenser 51 is connected to the pipeline between the outlet of the shell 41 and the air inlet of the second cylinder 22 through the cooling water pipeline 52. The cooling water pipeline 52 passes the condensed water produced by the condenser 51 to the gas transmission path from the outlet of the shell 41 to the second cylinder 22. In order to improve the economy of the unit, the condenser 51 is connected to the air outlet of the second cylinder 22. The condenser 51 is used to condense the exhaust gas of the second cylinder 22 into condensed water, and then transport the condensed water to the outlet of the shell 41 through the cooling water pipe 52. Therefore, the inlet end of the cooling water pipe 52 is connected to the air outlet of the second cylinder 22, and the outlet end of the cooling water pipe 52 is connected between the outlet of the shell 41 and the air inlet of the second cylinder 22. At the same time, a water pump 53 and a cooling water flow valve 54 are provided on the cooling water pipe 52 to facilitate the control of the flow of condensed water.

[0031] The number of reheaters (i.e., the number of chassis or sections) may be more than the first reheater 31 and the second reheater 32. When there are more than three reheaters, multiple reheat over-temperature suppression devices 4 are also provided. It is selected to provide one device 4 or not to provide device 4 between every two reheaters, and it is not necessary to provide device 4 between every two reheaters.

[0032] In order to better control the reheat overtemperature suppression device 4 to change the working state in time according to the requirements in the unit, multiple flow valves are added in the unit. A first flow valve 61 is arranged between the heat exchange medium outlet of the first reheater 31 and the heat exchange medium inlet of the second reheater 32, and a second flow valve 62 is arranged between the heat exchange medium outlet of the first reheater 31 and one end of the heat exchange tube 42 to control the steam amount of the reheater that needs to be cooled according to the situation; a third flow valve 63 is arranged between the air outlet of the first cylinder 21 and the air inlet of the second cylinder 22, and a fourth flow valve 64 is arranged between the air outlet of the first cylinder 21 and the inlet of the shell 41 to control the steam amount of the first cylinder 21 used to cool the reheater according to the situation.

[0033] The unit also includes a steam ejector, through which steam is extracted for heating. The ejector pipe of the steam ejector is connected to the air inlet of the third cylinder 23 and the pipeline between the boiler 1. The exhaust pipe of the steam ejector is connected to at least one of the first cylinder 21, the second cylinder 22, and the third cylinder 23. The exhaust pipe of the steam ejector is connected to the inlet of the shell 41. The steam ejector is used to extract low-temperature steam from the cylinder. After the low-temperature steam is heated to high-temperature steam through the reheat over-temperature suppression device 4, it can enter the thermal system for heating after pressure and temperature regulation.

[0034] In this embodiment, it should be noted that after the exhaust steam of the second cylinder 22 is heated, it will have a certain impact on the exhaust steam pressure of the second cylinder 22 (especially after the cooling device 4 is put into condensed water to adjust the steam temperature). It is necessary to simultaneously consider the allowable range of the exhaust steam pressure of the first cylinder 21 to ensure that the axial thrust of the turbine is within the allowable range. The second cylinder 22 of this embodiment is symmetrically arranged, so the change in pressure has basically no effect on the axial thrust of the second cylinder 22.

[0035] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A unit capable of suppressing overheating of a boiler reheater, the unit comprising a boiler, a first cylinder, and a second cylinder, the boiler being connected to an air inlet of the first cylinder, an air outlet of the first cylinder being connected to an air inlet of the second cylinder, an air pressure of the first cylinder being greater than an air pressure of the second cylinder, a reheater being arranged in a flue of the boiler, the reheater comprising a first reheater and a second reheater, a heat exchange medium outlet of the first reheater being connected to a heat exchange medium inlet of the second reheater, characterized in that: The unit further includes a reheat over-temperature suppression device, which is arranged outside the flue of the boiler, and includes a shell and a heat exchange tube, wherein the heat exchange tube is arranged in the shell, one end of the heat exchange tube is connected to the heat exchange medium outlet of the first reheater, and the other end is connected to the heat exchange medium inlet of the second reheater, the shell has an inlet and an outlet, the inlet of the shell is connected to the air outlet of the first cylinder, and the outlet of the shell is connected to the air inlet of the second cylinder; The reheat overtemperature suppression device further includes a temperature reduction component, which is used to reduce the steam temperature at the outlet of the shell, and the temperature reduction component is connected to a pipeline between the outlet of the shell and the air intake of the second cylinder.

2. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: The temperature reduction component includes a condenser and a temperature reduction water pipeline. The condenser is connected to the pipeline between the outlet of the shell and the air inlet of the second cylinder through the temperature reduction water pipeline.

3. The unit capable of suppressing overheating of a boiler reheater according to claim 2, characterized in that: The condenser is connected to the gas outlet of the second cylinder, and is used to condense the exhaust gas of the second cylinder into condensed water, and then transport the condensed water to the outlet of the shell through the cooling water pipeline.

4. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: The heat exchange tube has a plurality of bent sections and / or spiral sections.

5. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: The number of the reheaters is set to be at least three, and one reheat over-temperature suppression device is set between two of the reheaters, or the reheat over-temperature suppression device is not set.

6. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: A first flow valve is provided between the heat exchange medium outlet of the first reheater and the heat exchange medium inlet of the second reheater, and a second flow valve is provided between the heat exchange medium outlet of the first reheater and one end of the heat exchange tube.

7. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: A third flow valve is provided between the air outlet of the first cylinder and the air inlet of the second cylinder, and a fourth flow valve is provided between the air outlet of the first cylinder and the inlet of the housing.

8. The unit capable of suppressing overheating of a boiler reheater according to claim 1, characterized in that: The unit further includes a third cylinder, an air inlet and an air outlet of the third cylinder are both connected to the boiler, and an air pressure of the third cylinder is greater than an air pressure of the first cylinder.

9. The unit capable of suppressing overheating of a boiler reheater according to claim 8, characterized in that: The unit also includes a steam ejector, the ejector pipe of the steam ejector is connected to the air inlet of the third cylinder and the pipeline between the boiler, the exhaust pipe of the steam ejector is connected to at least one of the first cylinder, the second cylinder and the third cylinder, and the outlet pipe of the steam ejector is connected to the inlet of the shell.

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