Background
With the diversified development of the electric power market in China, the thermal power plant also takes on the task of supplying steam to industrial thermal users besides generating and supplying heat, and even the construction of some large-scale petroleum and chemical industries needs small and medium-sized thermal power plants as supporting facilities.
Generally, a direct steam supply mode is adopted for supplying steam to industrial heat users by a thermal power plant, according to an industrial process flow, saturated steam is needed by most of heat users at the tail end of the industrial heat users, steam supplied by the thermal power plant is interstage steam extraction of a steam turbine, the steam pressure is very large and unadjustable, the steam pressure is very high compared with the requirement of the heat users, the quality needed by the industrial steam is difficult to be completely matched, for example, 1MPa industrial steam is taken as an example, if supercritical unit steam is used, the air source of the supercritical unit steam extraction can only be three-section steam extraction of the unit, the rated pressure of the three-section steam extraction of the supercritical unit is about 2.1MPa, and the pressure difference of about 1MPa is caused between the industrial steam supply and the requirement of the heat users. Meanwhile, the industrial steam supplied by the steam turbine set generally has a superheat degree of about 100 ℃, even higher, and belongs to high-grade energy, in order to meet the requirements of heat consumers, the superheat degree of the steam is usually reduced in a temperature and pressure reducing mode or the superheated steam is converted into saturated steam, and as a result, the heat of the high-grade superheat degree is depreciated into low-grade energy, especially, a part with working capacity in the high-grade steam is wasted, and most of the processes of using the industrial steam by the heat consumers are not recoverable or polluted, so that the working medium loss of the system is large, the corresponding chemical water supplement amount is also large, and the water treatment system and equipment are huge, so that the operation cost is increased.
Therefore, for an industrial steam supply system in which the quality of the parameters of industrial steam supplied from a steam turbine is far higher than the parameters of steam required by a heat consumer, a simple and reasonable system is needed to convert a part of industrial steam with working capacity into electric energy by means of power equipment, realize the cascade utilization of the energy of the industrial steam and improve the economy of a unit.
SUMMERY OF THE UTILITY MODEL
The utility model discloses the technical problem that needs to solve provides a thermal power plant's industry steam step utilizes asynchronous power generation system, realizes the step utilization of industry steam energy, improves the economic nature of unit.
In order to solve the technical problem, the utility model adopts the following technical proposal.
An asynchronous power generation system for cascade utilization of industrial steam in a thermal power plant comprises an industrial steam supply pipeline for supplying steam to a thermal user, wherein a temperature and pressure reducing device is arranged on the industrial steam supply pipeline; the temperature and pressure reducing device is connected with an adjusting valve for controlling steam supply flow in parallel, an industrial steam supply pipeline adjusting valve is arranged on an industrial steam supply pipeline positioned at the front end of the adjusting valve, and the front end of the industrial steam supply pipeline adjusting valve is connected with a generator set for generating power through a pipeline; the power generating set comprises industrial turbines which are connected to the front side and the rear side of an industrial steam supply pipeline regulating valve through pipelines, the industrial turbines are connected with a power generator for generating power, and the output end of the power generator is connected to a 6kV station service power working section; the industrial steam turbine is connected and is provided with the industry steam turbine steam inlet governing valve on the admission pipeline of industry steam supply pipeline governing valve door front end, and the industry steam turbine is connected and is provided with the industry steam turbine exhaust pipeline valve on the play steam pipeline of industry steam supply pipeline governing valve door rear end.
Above-mentioned asynchronous power generation system is utilized to thermal power plant's industrial steam cascade, the front end of 6kV house service power working section is provided with the circuit breaker that is used for cutting off the power supply.
The asynchronous power generation system for cascade utilization of industrial steam of the thermal power plant is characterized in that the industrial steam turbine is a back pressure steam turbine.
According to the asynchronous power generation system for gradient utilization of industrial steam of the thermal power plant, the power generator (4) is an asynchronous power generator.
According to the asynchronous power generation system for cascade utilization of industrial steam of the thermal power plant, the industrial steam turbine is coaxially connected with the power generator.
Due to the adoption of the technical scheme, the utility model has the following technical progress.
The utility model discloses an add the industry steam turbine and drag asynchronous generator and generate electricity earlier thermal power plant's industrial steam and supply with the heat consumer again, under the electric load operating mode of difference, can enough guarantee normal industry and supply vapour, make the industrial steam energy obtain utilizing the maximize again, realized the step utilization of industrial steam energy.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
An asynchronous power generation system for cascade utilization of industrial steam in a thermal power plant is structurally shown in figure 1 and comprises an industrial steam supply pipeline 1, a temperature and pressure reducing device 8 and a generator set. Industry supplies vapour pipeline 1 to connect on thermal power plant's steam conduit for supply vapour to the heat consumer, and temperature and pressure reducer 8 sets up on industry supplies vapour pipeline, is used for reducing the temperature and the pressure of steam, and generating set connects in parallel and sets up on industry supplies vapour pipeline 1, is used for supplying power for 6kV station service electric working section 10.
The temperature and pressure reducing device 8 is provided with a regulating valve 7 in parallel, the regulating valve 7 is arranged on the industrial steam supply pipeline 1 and used for controlling the steam supply flow of the industrial steam supply pipeline, the industrial steam supply pipeline 1 at the front end of the regulating valve 7 is provided with an industrial steam supply pipeline regulating valve 6, and the generator set is arranged in parallel with the industrial steam supply pipeline regulating valve 6.
The power generating unit includes an industrial steam turbine 3 and a generator 4. The industrial steam wheel group 3 is connected at the both ends of industrial steam supply pipeline adjusting valve 6 through the pipeline, the steam inlet pipeline of industrial steam turbine 3 is connected at the front end of industrial steam supply pipeline adjusting valve 6, be provided with industrial steam turbine steam inlet adjusting valve 2 on the steam inlet pipeline, be used for adjusting the admission flow of industrial steam turbine 3, the rear end at industrial steam supply pipeline adjusting valve 6 is connected to the play steam pipeline of industrial steam turbine 3, be provided with industrial steam turbine exhaust steam pipeline valve 5 on the play steam pipeline, be used for adjusting the play steam flow of industrial steam turbine 3. The industrial turbine is coaxially connected with the generator. The operation and the stop of the industrial turbine 3 are controlled by the industrial turbine steam inlet regulating valve 2 and the industrial turbine steam exhaust pipeline valve 5.
The industrial steam turbine 3 is a back pressure steam turbine, the generator 4 is an asynchronous generator, and compared with a synchronous generator, the system is small in occupied area and low in investment, and is easier to implement.
The output at industrial steam turbine 3 is connected to generator 4, and the output of generator 4 is connected on 6kV station service electric working section 10 for supply power for 6kV station service electric working section 10. The front end of the 6kV auxiliary power working section 10 is provided with a circuit breaker 9 for cutting off power supply, and the power supply can be cut off at any time.
In order to match the industrial steam supply parameter with the steam inlet parameter of the industrial steam turbine 3 and achieve the purpose of gradient utilization of industrial steam energy, and simultaneously, the steam supply of hot users is not influenced, the steam inlet parameter design value of the industrial steam turbine 3 used in the invention is the mean value of the annual average steam supply parameter of the unit before temperature and pressure reduction, and the steam discharge parameter design value of the industrial steam turbine 3 is more than or equal to the steam parameter of the tail-end hot users.
When the industrial steam supply parameter is more than or equal to the designed steam inlet parameter of the industrial steam turbine, the industrial steam turbine is put into use, at the moment, the regulating valve and the temperature and pressure reducing device of the industrial steam supply pipeline are closed, and the steam inlet regulating valve, the steam exhaust pipeline valve and the regulating valve of the industrial steam turbine are opened at the same time, so that the industrial steam turbine operates at rated power without variable working condition regulation; the generated energy of the generator is merged into a 6kV station service power working section and is consumed in the section.
When the industrial steam supply parameter is between the designed steam inlet parameter of the industrial steam turbine and the steam parameter of the end heat user, determining whether the industrial steam turbine is put into use according to whether the steam exhaust parameter of the industrial steam turbine meets the steam parameter of the end heat user, if the steam exhaust parameter of the industrial steam turbine still meets the steam parameter of the end heat user, the industrial steam turbine operates in a mode that an adjusting valve is fully opened, if the steam exhaust parameter of the industrial steam turbine cannot meet the steam parameter of the end heat user, the industrial steam turbine is not put into use, at the moment, an inlet adjusting valve of the industrial steam turbine and an exhaust pipeline valve of the industrial steam turbine are closed, an adjusting valve and an adjusting valve of an industrial steam supply pipeline are opened, and meanwhile, a temperature reduction pressure reducer; when the industrial steam turbine is overhauled or is stopped due to a fault, only the industrial steam supply pipeline regulating valve and the temperature and pressure reducing device are opened, and normal steam supply of the system is ensured.
The utility model provides an independent operation is cut off in commissioning of industrial steam turbine, to industry steam supply system not production influence, after industry turbo generator set generated energy incorporated into host computer station service power working section in addition, this section consumes on the spot, has reduced host computer station service power consumption, has reduced station service power rate.
The effects of the present invention will be described with reference to specific examples.
A No. 1 unit of a certain power plant is a 350MW supercritical, steam extraction heat supply and wet condensing steam type steam turbine, wherein three-section steam extraction of the steam turbine is adopted as an industrial steam supply source, and the rated parameters of the three-section steam extraction are as follows: the pressure is 2.16MPa and the temperature is 453 ℃. The steam parameters for industrial heat load design are as follows: the pressure is 0.8-0.9 MPa, the temperature is 380-400 ℃, the rated industrial steam flow is 50t/h, the industrial steam supply is regulated through the temperature and pressure reducing device, so that the external steam supply is realized, the waste of high-grade steam is caused, and a back pressure turbine asynchronous power generation system is additionally arranged for realizing the gradient utilization of industrial steam energy. The three-stage steam extraction parameters of the unit under the working conditions of 100% THA, 75% THA and 50% THA are shown in Table 1.
TABLE 1 three-stage steam extraction parameters for different load sections
According to three-section steam extraction parameters of different load sections of the unit, when the load of the unit is above 175MW, the three-section steam extraction parameters are all higher than steam parameters for a terminal hot user, and the annual average value of the three-section steam extraction parameters of the unit is counted: the pressure is 1.8MPa, the temperature is 455 ℃ as the design value of the steam inlet parameter of the industrial steam turbine, and the main technical parameters of the added industrial steam turbine are determined to be as follows through checking calculation according to the steam parameter and the steam quantity required by a heat user: the steam admission pressure is 1.8MPa, the steam admission temperature is 455 ℃, and the steam admission amount is 50 t/h; the exhaust pressure is 0.9MPa, the exhaust temperature is 385 ℃, the internal efficiency of the steam turbine is 65 percent, the rated power of the asynchronous generator is 1800kW, the internal efficiency of the asynchronous generator is 95 percent, the mechanical efficiency is 99 percent, and the rotating speed is 3000 r/min. The generated energy of the asynchronous generator is merged into the 6kV working A section of the No. 1 unit to replace part of the auxiliary power of the host.
According to the comparison of three-section steam extraction parameters of different load sections with design parameters of the industrial steam turbine, when the unit operation load is 75% load or above, the unit operation load is put into the industrial steam turbine, and the rest load sections are not put into the industrial steam turbine.
Counting the running time proportion of each working condition of the unit in one year as 100% THA: 75% THA: the 50% THA is 3:5:2, calculated for 300 days of unit operation per year, and the power generation of the industrial turbine is shown in table 2.
TABLE 2 generated energy of industrial steam turbine
Benefit analysis
The industrial steam asynchronous power generation system ensures industrial steam, realizes the gradient utilization of industrial steam energy to the maximum extent, and reduces the plant power consumption rate and the power supply coal consumption of the unit by merging generated energy into a plant power system. The energy-saving benefit calculation takes the following parameters as the benchmark: the industrial steam turbine operates for 240 days all the year, the annual power generation of the unit No. 1 is 18 hundred million kWh, the annual power supply coal consumption of the unit No. 1 is 285g/kWh, the price of the on-grid power is 0.36 yuan/kWh, and the annual total power generation amount after the industrial steam turbine asynchronous power generation system is put into the industrial steam turbine asynchronous power generation system is 928.6 million kWh.
The power generation benefit is as follows: 928.6 ten thousand kWh × 0.36 ═ 334.30 ten thousand yuan
Reducing the plant power rate: 928.6 ÷ (18 × 10000). times.100 ═ 0.52%
The annual power supply coal consumption of the No. 1 unit is reduced: 285 × 0.52% ═ 1.48 g/kWh.