阅读说明：本技术 一种燃煤发电机组热力储能调频系统及方法 (Thermal energy storage frequency modulation system and method for coal-fired power generating unit ) 是由 赵国钦 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种燃煤发电机组热力储能调频系统及方法,包括锅炉过热器、锅炉再热器、高压缸、中压缸、低压缸、凝结水泵、凝结水调节阀、第三低压加热器抽汽调节阀、第四低压加热器抽汽调节阀、凝汽器、第一级低压换热器、第二级低压换热器、第三级低压换热器、第四级低压换热器、除氧器、第一级高压换热器、第二级高压换热器、第三级高压换热器、给水泵；本发明能够提高发电机的发电功率,不仅满足燃煤汽轮机组调频的需求,而且整个系统的投资成本低,结构简单,控制简便,使用寿命长,不需要定期更换设备。(The invention discloses a thermal energy storage frequency modulation system and method for a coal-fired generator set, and the system comprises a boiler superheater, a boiler reheater, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a condensate pump, a condensate water regulating valve, a third low-pressure heater steam extraction regulating valve, a fourth low-pressure heater steam extraction regulating valve, a condenser, a first-stage low-pressure heat exchanger, a second-stage low-pressure heat exchanger, a third-stage low-pressure heat exchanger, a fourth-stage low-pressure heat exchanger, a deaerator, a first-stage high-pressure heat exchanger, a second-stage high-pressure heat exchanger, a third-; the invention can improve the generating power of the generator, not only meets the requirement of frequency modulation of the coal-fired steam turbine set, but also has the advantages of low investment cost of the whole system, simple structure, simple and convenient control, long service life and no need of regularly replacing equipment.)

1. A coal-fired generating set thermal energy storage frequency modulation system which is characterized by comprising:

a working steam loop: sequentially flows through a boiler superheater (14a), a high-pressure cylinder (16), a boiler reheater (14b), an intermediate-pressure cylinder (17) and a low-pressure cylinder (18);

a condensed water loop: sequentially flows through a condenser (5), a condensate pump (1), a condensate regulating valve (2), a first-stage low-pressure heat exchanger (6), a second-stage low-pressure heat exchanger (7), a third-stage low-pressure heat exchanger (8), a fourth-stage low-pressure heat exchanger (9) and a deaerator (10);

a water supply loop: the waste water flows from the deaerator (10) to a boiler superheater (14a) through a feed water pump (15), a first-stage high-pressure heat exchanger (11), a second-stage high-pressure heat exchanger (12) and a third-stage high-pressure heat exchanger (13) in sequence;

nine steam pumping branches: the high-pressure heat exchanger (13) from a high-pressure cylinder (16) to a third-stage high-pressure heat exchanger, the high-pressure heat exchanger (12) from the high-pressure cylinder (16) to a second-stage high-pressure heat exchanger, the deaerator (10) from an intermediate-pressure cylinder (17), the first-stage high-pressure heat exchanger (11) from the intermediate-pressure cylinder (17), the condenser (5) from the low-pressure cylinder (18), the first-stage low-pressure heat exchanger (6) from the low-pressure cylinder (18), the second-stage low-pressure heat exchanger (7) from the low-pressure cylinder (7), the steam extraction regulating valve (3) from the low-pressure cylinder (18) to a third-stage low-pressure heat exchanger (8) from a third low-pressure heater, and the steam extraction.

2. The system for modulating the thermal energy storage and frequency modulation of a coal-fired power generating unit according to claim 1, wherein the third low-pressure heater steam extraction regulating valve (3) and the fourth low-pressure heater steam extraction regulating valve (4) are controlled by a control system.

3. The thermal energy storage frequency modulation system of the coal-fired power generating unit according to claim 1, wherein two steam outlets are symmetrically arranged at two axial ends of the low pressure cylinder (18), and both the two steam outlets are connected with a condenser.

4. A coal-fired power generating unit thermal energy storage frequency modulation method is characterized in that the frequency modulation method is based on the coal-fired power generating unit thermal energy storage frequency modulation system of claim 1, and comprises the following steps:

a, when the turbo generator set responds to the quick load up-regulation of the power grid:

closing the third low-pressure heater steam extraction regulating valve (3), reducing the opening degrees of the fourth low-pressure heater steam extraction regulating valve (4) and the condensed water regulating valve (2), reducing the water supply quantity and the extracted steam quantity at the outlet of the condensed water regulating valve (2), and enabling the steam which originally flows to the first-stage low-pressure heat exchanger (6), the second-stage low-pressure heat exchanger (7), the third-stage low-pressure heat exchanger (8) and the fourth-stage low-pressure heat exchanger (9) to flow back to the low-pressure cylinder (18) to continue to do work, so that the work quantity of the low-pressure cylinder (18) is increased, and the power generation power of the generator is increased;

the steam extraction amount of the first-stage high-pressure heat exchanger (11), the second-stage high-pressure heat exchanger (12) and the third-stage high-pressure heat exchanger (13) is unchanged, the coal supply amount of a boiler superheater (14a) and a boiler reheater (14b) is increased, the pressure of the feed water pump (15) is increased to increase the feed water amount conveyed to the boiler superheater (14a) and the boiler reheater (14b), so that the work amount of the high-pressure cylinder (16) and the medium-pressure cylinder (17) is increased, and the power generation power of the generator is further improved;

b, when the load of the steam turbine generator unit responding to the power grid is kept stable:

gradually opening the steam extraction regulating valve (3) of the third low-pressure heater, increasing the opening degree of the steam extraction regulating valve (4) of the fourth low-pressure heater and the condensed water regulating valve (2), recovering the water supply quantity of the outlet of the condensed water regulating valve (2), leading the steam extraction quantity of the low-pressure cylinder (18) to tend to be stable, leading the extracted steam to respectively enter the first-stage low-pressure heat exchanger (6), the second-stage low-pressure heat exchanger (7), the third-stage low-pressure heat exchanger (8) and the fourth-stage low-pressure heat exchanger (9) as heat sources to exchange heat with the condensed water flowing out of the condensed water regulating valve (2), leading the condensed water after heat exchange to sequentially pass through the deaerator (10), the water supply pump (15), the first-stage high-pressure heat exchanger (11), the second-stage high-pressure heat exchanger (12) and the third-stage high-pressure heat exchanger (13) and then enter a boiler superheater (14a) to form steam to, thereby keeping the generator stable generating power.

5. The coal-fired power generation unit thermal energy storage frequency modulation method according to claim 4, characterized in that the amount of water stored in the deaerator is larger than the maximum water usage amount of a boiler superheater (14a) in five minutes.

6. The coal-fired power generating set thermal energy storage frequency modulation method according to claim 4, wherein in the step A, the steps of closing the third low-pressure heater steam extraction regulating valve (3) and reducing the opening degrees of the fourth low-pressure heater steam extraction regulating valve (4) and the condensed water regulating valve (2) are completed within 2-3 seconds.

Technical Field

The invention relates to a thermal energy storage frequency modulation system of a coal-fired generator set. The invention also relates to a thermal energy storage frequency modulation method for the coal-fired power generating unit.

Background

The coal-fired steam combined system is characterized in that exhaust gas of a steam turbine is introduced into a boiler, high-temperature and high-pressure steam generated by the boiler drives a steam turbine set, and the steam turbine set drives a generator to generate electricity.

At present, along with the rapid improvement of the power generation proportion of new energy, the problem of insufficient frequency modulation capacity of a power grid is increasingly revealed, and the requirements on the flexibility of a coal-fired power generator set and the energy storage frequency modulation technology are higher and higher. The frequency modulation of the existing coal-fired generator set is mainly applied to a combined energy storage frequency modulation system, namely, an energy storage lithium battery pack and a power bidirectional conversion device are adopted as cores, and a data acquisition and monitoring system, a direct-current power distribution cabinet, a lightning protection grounding facility and the like are adopted as auxiliary equipment and are installed in an independent closed workshop. The combined energy storage frequency modulation system is a main energy storage frequency modulation system at present, has good frequency modulation flexibility and stable performance, but has the following problems:

(1) the theoretical charging and discharging times of the lithium battery are 2000 times, but when the unit normally operates, peak frequency modulation is required at least 2-4 times every day, namely, the battery needs to be charged and discharged 2-4 times every day. The generator set runs for about 300 days every year, so that the actual service life of the battery is only 1.7-3.3 years, and a large number of battery packs need to be replaced when the service life expires.

(2) The environmental protection problem of old and useless lithium cell processing, the processing of old and useless lithium cell has not realized innocent treatment yet, still discharges a large amount of harmful heavy metal and toxic substance to the environment in the processing procedure.

(3) The investment cost is high, and the investment of the combined energy storage frequency modulation system is high currently. Taking a 600MW unit as an example, the energy storage system needs 18MWh capacity, and the investment cost of the whole set of equipment is about 10000 ten thousand yuan.

(4) The problem of occupying the site, the combined energy storage frequency modulation system needs a special site to construct a totally-enclosed plant, taking a 600MW unit as an example, the occupied area of the plant is large.

Disclosure of Invention

The invention provides a thermal energy storage frequency modulation system of a coal-fired power generating set.

The invention aims to solve the second technical problem of providing a thermal energy storage frequency modulation method of a coal-fired power generating unit corresponding to the system.

The frequency modulation system and the method can rapidly improve the power generation power of the generator, not only meet the requirement of peak frequency modulation of the coal-fired steam turbine set, but also have the advantages of small occupied area and low investment cost of the whole system.

To solve the first technical problem, the technical solution adopted by the present invention is as follows:

a coal-fired generating set thermal energy storage frequency modulation system which characterized in that includes:

a working steam loop: sequentially flowing through a boiler superheater, a high-pressure cylinder, a boiler reheater, an intermediate-pressure cylinder and a low-pressure cylinder;

a condensed water loop: the system comprises a condenser, a condensate pump, a condensate regulating valve, a first-stage low-pressure heat exchanger, a second-stage low-pressure heat exchanger, a third-stage low-pressure heat exchanger, a fourth-stage low-pressure heat exchanger and a deaerator which sequentially flow through the condenser, the condensate pump, the condensate regulating valve, the first-stage low-pressure heat exchanger, the second-stage low;

a water supply loop: the water flows from the deaerator to a boiler superheater through a water feeding pump, a first-stage high-pressure heat exchanger, a second-stage high-pressure heat exchanger and a third-stage high-pressure heat exchanger in sequence;

nine steam pumping branches: the high-pressure cylinder to the third-stage high-pressure heat exchanger, the high-pressure cylinder to the second-stage high-pressure heat exchanger, the intermediate pressure cylinder to the deaerator, the intermediate pressure cylinder to the first-stage high-pressure heat exchanger, the low-pressure cylinder to the condenser, the low-pressure cylinder to the first-stage low-pressure heat exchanger, the low-pressure cylinder to the second-stage low-pressure heat exchanger, the low-pressure cylinder to the third-stage low-pressure heat exchanger through the third low-pressure heater steam extraction regulating valve, and the low-pressure cylinder to the third-stage low-pressure heat.

The third low-pressure heater steam extraction regulating valve and the fourth low-pressure heater steam extraction regulating valve are controlled by a control system.

Two steam outlets are symmetrically arranged at two axial ends of the low-pressure cylinder, and both the two steam outlets are connected with a condenser.

A thermal energy storage frequency modulation method of a coal-fired power generating unit corresponding to the system is characterized by comprising the following steps:

a, when the turbo generator set responds to the quick load up-regulation of the power grid:

closing the steam extraction regulating valve of the third low-pressure heater, reducing the opening degrees of the steam extraction regulating valve and the condensed water regulating valve of the fourth low-pressure heater, reducing the water supply quantity of the outlet of the condensed water regulating valve and the extracted steam quantity, and enabling the steam which originally flows to the first-stage low-pressure heat exchanger, the second-stage low-pressure heat exchanger, the third-stage low-pressure heat exchanger and the fourth-stage low-pressure heat exchanger to flow back into the low-pressure cylinder to continue to do work, so that the work quantity of the low-pressure cylinder is increased, and the power generation power of the generator is;

the extraction steam volume of the first-stage high-pressure heat exchanger, the second-stage high-pressure heat exchanger and the third-stage high-pressure heat exchanger is unchanged, the coal supply volume of a boiler superheater and a boiler reheater is increased, and the pressure of a feed water pump is increased to increase the water supply volume delivered to the boiler superheater and the boiler reheater, so that the work capacity of a high-pressure cylinder and a medium-pressure cylinder is increased, and the power generation power of a generator is further improved;

b, when the load of the steam turbine generator unit responding to the power grid is kept stable:

the steam extraction regulating valve of the third low-pressure heater is gradually opened, the opening degrees of the steam extraction regulating valve and the condensate regulating valve of the fourth low-pressure heater are increased, the water supply quantity of the outlet of the condensate regulating valve is stable, the steam extraction quantity of the low-pressure cylinder is stable, extracted steam enters the first-stage low-pressure heat exchanger, the second-stage low-pressure heat exchanger, the third-stage low-pressure heat exchanger and the condensate flowing out of the condensate regulating valve as a heat source in the fourth-stage low-pressure heat exchanger to exchange heat, the condensate after heat exchange sequentially passes through the deaerator, the water supply pump, the first-stage high-pressure heat exchanger, the second-stage high-pressure heat exchanger and the third-stage high-pressure heat exchanger and then enters the boiler to form steam to enter the steam turbine set to do.

The water stored in the deaerator is larger than the maximum water consumption of a boiler within five minutes.

In the step A, the closing of the steam extraction regulating valve of the third low-pressure heater and the reduction of the opening degrees of the steam extraction regulating valve and the condensate water regulating valve of the fourth low-pressure heater are all completed within 2-3 seconds.

Compared with the prior art, the technology of the invention has the following advantages:

(1) at the moment that the coal-fired steam turbine set needs a peak to provide higher electric energy, the flow of the superheated steam for heating the condensed water is quickly reduced, the reduced superheated steam flows back to a low-pressure cylinder of the steam turbine set to continuously do work, the mechanical energy of the steam turbine set is improved, the steam turbine set drives a generator to generate electricity, and the mechanical energy is converted into electric energy, so that the power generation power of the generator is quickly improved, the requirement of frequency modulation of the coal-fired steam turbine set is met, the whole system is simple in structure, low in investment cost, simple and convenient to control, long in service life and free of periodical equipment replacement;

(2) the flow rate of condensed water can be reduced, so that the steam flow supplied to the deaerator by the steam turbine unit is reduced, the reduced superheated steam flows back to a low-pressure cylinder of the steam turbine unit to continue acting, the mechanical energy of the steam turbine is improved, and the generator is driven to generate and output electric energy;

(3) the system can continuously provide higher and stable energy for the steam turbine and maintain the generated power of the steam turbine generator unit after being increased;

(4) after the combustion heat load supplied by the boiler combustion part of the coal-fired unit is stably increased, the steam extraction system and the condensed water system of the turbine thermodynamic system are quickly stabilized to a full-flow state, the boiler combustion system continuously increases the coal-fired supply quantity, and the power generation power output by the coal-fired unit can be continuously and stably increased.

Drawings

The invention is described in further detail below with reference to the figures and the specific embodiments

FIG. 1 is a schematic structural diagram of a thermal energy storage frequency modulation system of a coal-fired power generating unit according to the invention;

1-a condensate pump, 2-a condensate water regulating valve, 3-a third low-pressure heater steam extraction regulating valve, 4-a fourth low-pressure heater steam extraction regulating valve, 5-a condenser, 6-a first-stage low-pressure heat exchanger, 7-a second-stage low-pressure heat exchanger, 8-a third-stage low-pressure heat exchanger, 9-a fourth-stage low-pressure heat exchanger, 10-a deaerator, 11-a first-stage high-pressure heat exchanger, 12-a second-stage high-pressure heat exchanger, 13-a third-stage high-pressure heat exchanger, 14 a-a boiler superheater, 14 b-a boiler reheater, 15-a water feed pump, 16-a high-pressure cylinder, 17-an intermediate pressure cylinder and 18-a low.

Detailed Description

Referring to fig. 1, the thermal energy storage frequency modulation system of the coal-fired power generating unit of the embodiment includes a boiler superheater 14a, a boiler reheater 14b, a high-pressure cylinder 16, an intermediate-pressure cylinder 17, a low-pressure cylinder 18, a condensate pump 1, a condensate regulating valve 2, a third low-pressure heater steam extraction regulating valve 3, a fourth low-pressure heater steam extraction regulating valve 4, a condenser 5, a first-stage low-pressure heat exchanger 6, a second-stage low-pressure heat exchanger 7, a third-stage low-pressure heat exchanger 8, a fourth-stage low-pressure heat exchanger 9, a deaerator 10, a first-stage high-pressure heat exchanger 11, a second-stage high-pressure heat exchanger 12, a third-stage;

in fig. 1: the thin solid line is condensed water, the thick solid line is feed water, and the dot-dash line is acting steam; the thin dotted line is the extracted steam.

Working steam flow: an inlet of the high pressure cylinder 16 is connected to an outlet of the boiler superheater 14a, a first outlet of the high pressure cylinder 16 is connected to an inlet of the boiler reheater 14b, an inlet of the intermediate pressure cylinder 17 is connected to an outlet of the boiler reheater 14b, and an inlet of the low pressure cylinder 18 is connected to a third outlet of the intermediate pressure cylinder 17.

Steam extraction flow: a second outlet of the high-pressure cylinder 16 is connected with a second inlet of the third-stage high-pressure heat exchanger 13, and a third outlet of the high-pressure cylinder 16 is connected with a second inlet of the second-stage high-pressure heat exchanger 12; a first outlet of the intermediate pressure cylinder 17 is connected with a first inlet of the deaerator 10, and a second outlet of the intermediate pressure cylinder 17 is connected with a second inlet of the first-stage high-pressure heat exchanger 11; the first outlet of the low-pressure cylinder 18 is connected with the inlet of a fourth low-pressure heater steam extraction regulating valve 4, the outlet of the fourth low-pressure heater steam extraction regulating valve 4 is connected with the second inlet of a fourth-stage low-pressure heat exchanger 9, the second outlet of the low-pressure cylinder 18 is connected with the inlet of a third low-pressure heater steam extraction regulating valve 3, the outlet of the third low-pressure heater steam extraction regulating valve 3 is connected with the second inlet of a third-stage low-pressure heat exchanger 8, the third outlet of the low-pressure cylinder 18 is connected with the second inlet of a second-stage low-pressure heat exchanger 7, the fourth outlet of the low-pressure cylinder 18 is connected with the second inlet of a first-stage low-pressure heat exchanger 6, and the steam exhaust port of the low-pressure cylinder 18 is sequentially connected with a condenser 5, a condensate pump 1 and a.

A water supply flow: an outlet of the deaerator 10 is connected with an inlet of a feed water pump 15, an outlet of the feed water pump 15 is connected with a first inlet of a first-stage high-pressure heat exchanger 11, an outlet of the first-stage high-pressure heat exchanger 11 is connected with a first inlet of a second-stage high-pressure heat exchanger 12, an outlet of the second-stage high-pressure heat exchanger 12 is connected with a first inlet of a third-stage high-pressure heat exchanger 13, and an outlet of the third-stage high-pressure heat exchanger 13 is connected with an inlet of a boiler superheater 14 a;

a condensed water flow: condenser 5 is through condensate pump 1, the water side entry of condensate water regulating valve 2 to first order low pressure heat exchanger 6, the water side export of first order low pressure heat exchanger 6 links to each other with the water side entry of second level low pressure heat exchanger 7, the water side export of second level low pressure heat exchanger 7 links to each other with the water side entry of third level low pressure heat exchanger 8, the water side export of third level low pressure heat exchanger 8 links to each other with the water side entry of fourth level low pressure heat exchanger 9, the water side export of fourth level low pressure heat exchanger 9 links to each other with the water side entry of oxygen-eliminating device 10.

The low pressure cylinder 18 of this embodiment is symmetrically provided with steam outlets at both axial ends, and the steam outlets are connected to the condenser 5.

The thermal energy storage frequency modulation method for the coal-fired power generating unit comprises the following steps:

A. when the power grid needs the fast peak of the coal-fired unit to improve the power generation power, the third low-pressure heater steam extraction regulating valve 3 is closed, and the opening degrees of the fourth low-pressure heater steam extraction regulating valve 4 and the condensed water regulating valve 2 are reduced; the water supply quantity and the extracted steam quantity at the outlet of the condensed water regulating valve 2 are reduced, so that the steam flowing to the first-stage low-pressure heat exchanger 6, the second-stage low-pressure heat exchanger 7, the third-stage low-pressure heat exchanger 8 and the fourth-stage low-pressure heat exchanger 9 flows back to the low-pressure cylinder 18 to continue to do work, the work quantity of the low-pressure cylinder 18 is increased, and the power generation power of the generator is increased;

the extraction steam volume of the first-stage high-pressure heat exchanger 11, the second-stage high-pressure heat exchanger 12 and the third-stage high-pressure heat exchanger 13 is unchanged, the coal supply volume of the boiler superheater 14a and the boiler reheater 14b is increased, the pressure of the water supply pump 15 is increased to increase the water supply volume delivered to the boiler superheater 14a and the boiler reheater 14b, so that the work volume of the hydraulic cylinder 16 and the hydraulic cylinder 17 is increased, and the power generation power of the generator is further improved;

B. when the load of the power grid is kept stable in response to the response of the turbo generator unit, the third low-pressure heater steam extraction regulating valve 3 is gradually opened, the opening degrees of the fourth low-pressure heater steam extraction regulating valve 4 and the condensed water regulating valve 2 are increased, the water supply quantity of the outlet of the condensed water regulating valve 2 is recovered, the steam extraction quantity of the low-pressure cylinder 18 is recovered, extracted steam respectively enters the first-stage low-pressure heat exchanger 6, the second-stage low-pressure heat exchanger 7, the third-stage low-pressure heat exchanger 8 and the fourth-stage low-pressure heat exchanger 9 to be used as a heat source to exchange heat with the condensed water flowing out of the condensed water regulating valve 2, the condensed water after heat exchange sequentially, and the water feeding pump 15, the first-stage high-pressure heat exchanger 11, the second-stage high-pressure heat exchanger 12 and the third-stage high-pressure heat exchanger 13 enter the boiler superheater 14a to form steam, and the steam enters the steam turbine set to do work again, so that the generator keeps stable generating power.

Therefore, the thermal energy storage frequency modulation system and the method thereof for the coal-fired power generating unit in the embodiment can rapidly reduce the flow of the superheated steam for heating the condensed water, the reduced part of the superheated steam flows back to the low-pressure cylinder of the steam turbine unit to continue acting, the mechanical energy of the steam turbine unit is improved, the steam turbine unit drives the power generator to generate power, and the mechanical energy is converted into electric energy, so that the power generation power of the power generator is rapidly improved, the requirement of frequency modulation of the coal-fired steam turbine unit is met, the investment cost of the whole system is low, the structure is simple and convenient to control, the service life is long, and equipment does not need.

The amount of water stored in the deaerator of this embodiment is greater than the maximum water usage of the boiler superheater 14a in five minutes.

In the step a of this embodiment, the closing of the third low-pressure heater steam extraction regulating valve 3 and the reduction of the opening degrees of the fourth low-pressure heater steam extraction regulating valve 4 and the condensate water regulating valve 2 are all completed within 2 to 3 seconds, so that the load factor of the coal-fired power generating unit can be increased by more than 1.3% within 2 to 3 seconds.

The above-described embodiments of the present invention are not intended to limit the scope of the present invention, and the embodiments of the present invention are not limited thereto, and various other modifications, substitutions and alterations can be made to the above-described structure of the present invention without departing from the basic technical concept of the present invention as described above, according to the common technical knowledge and conventional means in the field of the present invention.