Boiler reheat steam temperature adjusting system

Abstract

The utility model discloses a boiler reheat steam temperature adjusting system which comprises a steam turbine, a reheater water spraying desuperheater, a low-temperature reheater inlet header, a low-temperature reheater, a low-temperature reheater outlet header, a high-temperature reheater, a water feeding pump, an adjusting valve set, a reheat steam bypass, an electric valve and a manual valve. Primary temperature coarse adjustment is carried out through the reheat steam bypass, secondary temperature fine adjustment is carried out through water spraying temperature reduction, the flue gas flow field of the boiler cannot be affected, the occupied area of the boiler cannot be increased, the system is suitable for various types of boilers, system adjustment is simple, investment is low, the fault rate is low, maintenance is easy, and the efficiency of a boiler unit is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of boiler technology, and in particular to a boiler reheat steam temperature regulation system. Background Technology

[0002] Equipping boiler units with reheat systems can effectively improve their power generation efficiency. Currently, there are three main methods for regulating boiler reheat steam temperature:

[0003] Temperature control for flue gas damper.

[0004] Flue gas damper temperature control is achieved by controlling the opening of the damper gate, thereby changing the flue gas flow rate in the low-temperature reheater flue. By increasing or decreasing the flue gas flow rate, the amount of heat absorbed by the low-temperature reheater is controlled, thus achieving the purpose of regulating the reheat steam temperature.

[0005] Flue gas recirculation and temperature adjustment.

[0006] Flue gas recirculation temperature control utilizes a flue gas recirculation fan to draw a portion of low-temperature flue gas from the boiler's tail flue and directly feed it into the furnace through nozzles or through ducts and burners before entering the furnace, forming a flue gas recirculation process. After the low-temperature flue gas drawn from the boiler tail re-enters the furnace, it increases the flue gas flow rate in the reheater flue, enhances convective heat transfer, and raises the reheater outlet steam temperature. The reheat steam temperature is controlled by adjusting the flue gas flow rate using the fan.

[0007] Temperature adjustment using a water spray desuperheater.

[0008] Temperature regulation of the water spray desuperheater is achieved by supplying medium-pressure desuperheating water from the intermediate tap of the water pump, which is then sprayed into the reheat desuperheater on the reheat steam inlet pipe. The reheat steam temperature is controlled by adjusting the flow rate of the desuperheating water.

[0009] Flue gas regulating dampers adjust the reheat steam temperature by controlling the flue gas flow in two or three flue ducts. The varying flue gas flow rates at the outlets of each damper result in an uneven flue gas flow field, affecting heat exchange in subsequent heating surfaces and increasing the temperature difference between the flue gas and the surrounding air. Furthermore, in small combustion boilers and dry quenching waste heat boilers, flue gas dampers are unsuitable due to their small flue cross-sections. In gas turbine waste heat boilers, however, the large flue cross-sections and compact heating surface structure make the use of flue gas dampers not only costly but also increase the boiler's footprint.

[0010] Flue gas recirculation temperature control adds a recirculation fan, making system adjustment complex, increasing investment costs, and resulting in a high fan failure rate and difficulty in maintenance. On the other hand, the introduction of a large amount of low-temperature flue gas into the furnace will lower the furnace temperature and reduce the oxygen concentration inside the furnace, affecting the complete combustion of boiler fuels, especially low-calorific-value fuels, and reducing boiler efficiency.

[0011] Water spray desuperheaters are sensitive in temperature regulation. However, reheat water spray desuperheating increases the working fluid flow rate in the intermediate and low-pressure cylinders. This steam only performs work in the intermediate and low-pressure cylinders, thus limiting the work capacity of the high-pressure cylinder. This means that the efficiency of the high-pressure cylinder is affected in the entire regenerative system, consequently impacting the overall unit efficiency. In ultra-high-pressure units, using water spray desuperheating to regulate reheat steam temperature reduces unit efficiency by approximately 0.1-0.2%. This indicates that while water spray desuperheating is a sensitive method for adjusting steam temperature, it reduces boiler unit efficiency. Utility Model Content

[0012] To address the aforementioned technical problems, this utility model designs a boiler reheat steam temperature regulation system. Reheat steam bypass temperature regulation controls the steam flow rate entering the low-temperature reheater, thereby controlling the heat absorption of the reheater and achieving the purpose of regulating the steam temperature. Primary temperature coarse adjustment is performed via reheat steam bypass, and secondary temperature fine adjustment is performed via water spray desuperheating. This does not affect the boiler's flue gas flow field, does not increase the boiler's footprint, is suitable for various types of boilers, and features simple system adjustment, low investment, low failure rate, easy maintenance, and effectively improves boiler unit efficiency.

[0013] The present invention adopts the following technical solution:

[0014] A boiler reheat steam temperature regulation system includes a steam turbine, a reheater spray desuperheater, a low-temperature reheater inlet header, a low-temperature reheater, a low-temperature reheater outlet header, a high-temperature reheater, a feedwater pump, and a regulating valve group. The high-pressure cylinder exhaust steam of the steam turbine sequentially enters the reheater spray desuperheater, the low-temperature reheater inlet header, the low-temperature reheater, and the low-temperature reheater outlet header before entering the high-temperature reheater. Desuperheating water from the intermediate tap of the boiler feedwater pump is introduced into the reheater spray desuperheater after passing through the regulating valve group. The low-temperature reheater inlet header and the low-temperature reheater outlet header are connected by at least one reheat steam bypass, and a control valve is installed on the reheat steam bypass.

[0015] Preferably, the control valve includes a manual valve and an electric valve arranged in sequence.

[0016] Preferably, the reheat steam bypass is provided with 1 to 3 paths to improve the regulation performance of the reheat bypass.

[0017] Preferably, both the manual and electric valves on the reheat steam bypass are gate valves, which effectively reduces the resistance of the bypass pipeline.

[0018] Preferably, the reheater spray desuperheater adopts an inner sleeve structure to avoid damage to the equipment caused by excessive temperature difference.

[0019] The beneficial effects of this utility model are as follows: This utility model designs a boiler reheat steam temperature regulation system, which performs primary temperature coarse adjustment through reheat steam bypass and secondary temperature fine adjustment through water spray desuperheating. It does not affect the flue gas flow field of the boiler, does not increase the boiler footprint, is suitable for various types of boilers, has simple system adjustment, low investment, low failure rate, is easy to maintain, and effectively improves the efficiency of boiler units. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model;

[0021] In the diagram: 1. Steam turbine, 2. Reheater spray desuperheater, 3. Low-temperature reheater inlet header, 4. Low-temperature reheater, 5. Low-temperature reheater outlet header, 6. High-temperature reheater, 7. Feedwater pump, 8. Control valve group, 9. Reheat steam bypass, 10. Electric valve, 11. Manual valve. Detailed Implementation

[0022] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0023] Example: Figure 1 As shown, a boiler reheat steam temperature regulation system includes a steam turbine 1, a reheater spray desuperheater 2, a low-temperature reheater inlet header 3, a low-temperature reheater 4, a low-temperature reheater outlet header 5, a high-temperature reheater 6, a feedwater pump 7, a regulating valve group 8, a reheat steam bypass 9, an electric valve 10, and a manual valve 11.

[0024] The exhaust steam from the high-pressure cylinder of turbine 1 enters the reheater spray desuperheater 2, the low-temperature reheater inlet header 3, the low-temperature reheater 4, and the low-temperature reheater outlet header 5 in sequence before entering the high-temperature reheater 6. The desuperheating water from the intermediate tap of the boiler feedwater pump 7 is introduced into the reheater spray desuperheater 2 through the regulating valve group 8. The low-temperature reheater inlet header 3 and the low-temperature reheater outlet header 5 are connected by a reheat steam bypass 9, on which a manual valve 11 and an electric valve 10 are installed in sequence.

[0025] This invention uses a reheat steam bypass for primary temperature coarse adjustment and water spray desuperheating for secondary temperature fine adjustment. It does not affect the flue gas flow field of the boiler, does not increase the boiler footprint, is suitable for various types of boilers, has simple system adjustment, low investment, low failure rate, is easy to maintain, and effectively improves the efficiency of boiler units.

[0026] One to three reheat steam bypasses can be set up to improve the regulation performance of the reheat bypass.

[0027] Both manual and electric valves on the reheat steam bypass are gate valves, which effectively reduces the resistance of the bypass pipeline.

[0028] The reheater spray desuperheater adopts an inner sleeve structure to avoid equipment damage caused by excessive temperature difference.

[0029] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A boiler reheat steam temperature control system, characterized in that, It includes a steam turbine, a reheater spray desuperheater, a low-temperature reheater inlet header, a low-temperature reheater, a low-temperature reheater outlet header, a high-temperature reheater, a feedwater pump, and a regulating valve group. The high-pressure cylinder exhaust steam of the steam turbine sequentially enters the reheater spray desuperheater, the low-temperature reheater inlet header, the low-temperature reheater, and the low-temperature reheater outlet header before entering the high-temperature reheater. Desuperheating water from the intermediate tap of the boiler feedwater pump is introduced into the reheater spray desuperheater after passing through the regulating valve group. The low-temperature reheater inlet header and the low-temperature reheater outlet header are connected by at least one reheat steam bypass, and a control valve is installed on the reheat steam bypass.

2. The boiler reheat steam temperature control system according to claim 1, characterized in that, The control valves include a manual valve and an electric valve arranged in sequence.

3. The boiler reheat steam temperature control system according to claim 1, characterized in that, The reheat steam bypass is provided with 1 to 3 paths.

4. The boiler reheat steam temperature control system according to claim 2, characterized in that, Both the manual and electric valves on the reheat steam bypass are gate valves.

5. The boiler reheat steam temperature control system according to claim 1, characterized in that, The reheater spray desuperheater adopts an inner sleeve structure.

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