A shaft sealing system for a small steam turbine thermal system

Abstract

The present invention relates to a shaft sealing system of a small steam turbine thermal system, the shaft sealing system comprising a steam turbine, a three-way valve and a regulating valve; the front end shaft portion of the steam turbine is provided with a front steam seal body, and the rear end shaft portion is provided with a rear steam seal body; the first port of the three-way valve is connected to a steam source through the regulating valve, the second port is connected to the front steam seal body, and the third port is connected to the rear steam seal body; when starting the machine, the steam source leaks steam through a regulating valve and the three-way valve to the front steam seal, which greatly shortens the start-up time; and the front steam seal body is connected to the rear steam seal body through a three-way valve, which can achieve a self-sealing effect.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbines, and in particular to a shaft sealing system of a thermal system of a small steam turbine. Background Art

[0002] In recent years, high-speed steam turbines have been widely used around the world, and low-speed direct-connected units are gradually unable to meet users' demands for unit efficiency and energy saving and consumption reduction.

[0003] In the industry, small steam turbines generally refer to steam turbines with a power of less than 5MW. Due to their small power, they are mostly used in small regional power plants, industrial enterprise self-provided power plants, cogeneration power plants, fans and pump drivers, etc. In recent years, due to the rise in the prices of various fuels, in order to improve energy efficiency, users have continuously increased their requirements for the efficiency of steam turbine generator sets, and small steam turbines have begun to develop in the direction of high steam inlet parameters, high speed, and high efficiency.

[0004] At present, the efficiency of traditional small steam turbine products is generally low. Under the general situation of promoting green and low-carbon development of energy and structural transformation, such products are in urgent need of innovation and upgrading. The end-user transformation and new power plant construction have an urgent demand for energy-saving and high-efficiency energy and power equipment. The development of small high-parameter and high-speed steam turbines is a technical development direction and trend led by market demand. Summary of the invention

[0005] Aiming at the technical problems existing in the prior art, the present invention provides a shaft sealing system for a thermal system of a small steam turbine, abandons the pressure equalizing box required by traditional large turbines, and uses a three-way valve and a regulating valve to adjust the shaft sealing system, which greatly shortens the startup time.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: a shaft sealing system of a small steam turbine thermal system, the shaft sealing system comprising a steam turbine, a three-way valve and a regulating valve; a front steam seal body is arranged at the front shaft of the steam turbine, and a rear steam seal body is arranged at the rear shaft;

[0007] The first port of the three-way valve is connected to the steam source through the regulating valve, the second port is connected to the front steam seal body, and the third port is connected to the rear steam seal body.

[0008] The beneficial effects of the present invention are as follows: when starting the machine, the steam source leaks through a regulating valve and a three-way valve to the front steam seal, which greatly shortens the startup time; and the front steam seal body is connected to the rear steam seal body through a three-way valve, which can achieve a self-sealing effect.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the second port of the three-way valve is connected to one end of the front steam seal body close to the steam turbine, and the third port is connected to one end of the rear steam seal body close to the steam turbine.

[0011] Furthermore, new steam enters the steam inlet at the front end of the steam turbine through an integrated main steam fast-closing regulating valve; the front steam seal body and the rear steam seal body are commonly connected to the integrated main steam fast-closing regulating valve.

[0012] Furthermore, the integrated main steam fast-closing regulating valve connects one end of the front steam seal body away from the steam turbine and one end of the rear steam seal body away from the steam turbine.

[0013] Furthermore, the shaft seal system further comprises a condenser, a condensate pump and a steam seal heater; the top of the condenser is connected to the steam extraction port at the rear end of the steam turbine, and the bottom is connected to the water inlet of the condensate pump;

[0014] The water outlet of the condensate pump discharges the condensate through the steam seal heater; the steam seal heater is also connected to the front steam seal body and the rear steam seal body.

[0015] Furthermore, the steam seal heater connects one end of the front steam seal body away from the steam turbine and one end of the rear steam seal body away from the steam turbine.

[0016] Further, the third port of the three-way valve is connected to the top of the condenser.

[0017] Furthermore, the water outlet of the condensate pump is connected to the condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic structural diagram of a shaft sealing system of a small steam turbine thermal system.

[0019] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0020] 1. Steam turbine, 2. Integrated main steam fast closing regulating valve, 3. Condenser, 4. Condensate pump, 5. Front steam seal body, 6. Rear steam seal body, 7. Three-way valve, 8. Regulating valve, 9. Steam seal heater. DETAILED DESCRIPTION

[0021] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] like Figure 1As shown, a shaft sealing system of a small steam turbine thermal system includes a steam turbine 1, an integrated main steam fast-closing regulating valve 2, a condenser 3 and a condensate pump 4. The top of the condenser 3 is connected to the steam extraction port at the rear end of the steam turbine 1, and the bottom is connected to the water inlet of the condensate pump 4. New steam enters the steam turbine 1 from the steam inlet at the front end of the steam turbine 1 through the integrated main steam fast-closing regulating valve 2, and is extracted from the steam turbine 1 by the condenser 3, so that the steam turbine 1 performs work. The condenser 3 of this embodiment is a small condenser with a small footprint and high heat exchange efficiency. It can be suitable for various variable operating conditions, has four processes, a simple internal structure, is easy to manufacture and maintain, and has a size of about 2500x1500x2200mm. In addition, the main steam valve and the regulating valve are integrated and designed as an integrated main steam fast-closing regulating valve 2, which is small in size and has a regulating fast-closing function. It can be installed on the side of the head of the steam turbine 1 to reduce the footprint.

[0023] The shaft seal system further includes a front steam seal body 5, a rear steam seal body 6, a three-way valve 7, a regulating valve 8 and a steam seal heater 9. The front end shaft of the steam turbine 1 is equipped with the front steam seal body 4, and the rear end shaft is equipped with the rear steam seal body 5.

[0024] The first port of the three-way valve 7 is connected to the steam source through the regulating valve 8, the second port is connected to the end of the front steam seal body 5 close to the steam turbine 1, and the third port is connected to the end of the rear steam seal body 5 close to the steam turbine and the top of the condenser 3. And in this embodiment, the regulating valve 8 is an intelligent integrated regulating valve. The shaft sealing system of this embodiment abandons the pressure equalizing box required by the traditional large machine, and uses the three-way valve 7 and the intelligent integrated regulating valve 8 to adjust the shaft sealing system. The end of the front steam seal body 5 close to the steam turbine 1 is connected to the end of the rear steam seal body 5 close to the steam turbine through a three-way valve 7 to achieve a self-sealing effect. And when starting up, the steam source passes through an intelligent integrated regulating valve 8 and the three-way valve 7 to the front steam seal body 4, which greatly shortens the startup time. In this embodiment, the opening of the three-way valve 7 can also be controlled by an electrical signal to keep the output pressure at the required operating value. For example, when the steam flows back from the front steam seal body 4 to the three-way valve 7, the three-way valve 7 will discharge the excess steam into the condenser 3 to keep the pressure constant.

[0025] The water outlet of the condensate pump 4 discharges the excess condensate through the steam seal heater 9, and the water outlet of the condensate pump 4 is also connected to the condenser 3, so that the condensate can enter the condenser 3 to adjust the water level in the condenser 3 and better maintain the vacuum in the condenser 3.

[0026] The steam seal heater 9 is connected to the integrated main steam fast closing regulating valve 2, the end of the front steam seal body 4 away from the steam turbine 1, and the end of the rear steam seal body 5 away from the steam turbine 1, forming a shaft seal loop, further playing the role of self-sealing between the front steam seal body 4 and the rear steam seal body 5. In addition, the steam seal heater 9 can use the leaking steam to heat the condensed water to improve the circulation efficiency and keep each chamber at a vacuum of 0.001-0.005MPa.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A shaft sealing system for a small steam turbine thermal system, characterized in that: The shaft seal system includes a steam turbine, a three-way valve, a regulating valve, a condenser, a condensate pump and a steam seal heater; the front shaft of the steam turbine is provided with a front steam seal body, and the rear shaft is provided with a rear steam seal body; The first port of the three-way valve is connected to the steam source through the regulating valve, the second port is connected to one end of the front steam seal body close to the steam turbine, and the third port is connected to one end of the rear steam seal body close to the steam turbine and the top of the condenser; New steam enters the steam inlet at the front end of the steam turbine through an integrated main steam fast-closing regulating valve; the front steam seal and the rear steam seal are connected to the integrated main steam fast-closing regulating valve; the integrated main steam fast-closing regulating valve connects one end of the front steam seal away from the steam turbine and one end of the rear steam seal away from the steam turbine; The top of the condenser is connected to the steam extraction port at the rear end of the steam turbine, and the bottom is connected to the water inlet of the condensate pump; The water outlet of the condensate pump discharges the condensate through the steam seal heater; the steam seal heater is also connected to the front steam seal body and the rear steam seal body.

2. The shaft sealing system of the small steam turbine thermal system according to claim 1, characterized in that: The steam seal heater connects one end of the front steam seal body away from the steam turbine and one end of the rear steam seal body away from the steam turbine.

3. The shaft sealing system of the small steam turbine thermal system according to claim 1, characterized in that: The water outlet of the condensate pump is connected to the condenser.

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