CN112050190A - Thermoelectric peak regulation method for coal-fired unit - Google Patents

Abstract

A thermal and electrical peak regulation method for coal-fired units, the method is based on a high-low side double injection system, according to the total thermal and electrical load, to determine the boiler outlet steam flow; The opening of the steam inlet control valve makes the superheated steam split into the high side ejector and the high pressure cylinder of the steam turbine respectively. Adjust the steam flow into the throat of the high-by-pass ejector and the low-pressure cylinder; by adjusting the opening of the inlet-steam regulating valve and the low-pressure bypass regulating valve of the medium-pressure cylinder, the reheated steam is divided into the middle-pressure cylinder and the low-bypass ejection of the steam turbine. The ratio of the inlet steam flow of the medium pressure cylinder to the inlet steam flow of the high pressure cylinder is kept close to the design ratio; the outlet steam of the low bypass ejector goes to the heating steam main pipe; this method realizes the maximum thermal peak regulation and deep ESC peak, significantly improving the unit's adaptive thermal peak shaving capability and deep electrical peak shaving capability.

Description

A method for thermal and electrical peak regulation of coal-fired units

technical field

The invention relates to the power and heat supply technology in the field of energy power, in particular to a thermal and electrical peak regulation method for a coal-fired unit.

Background technique

Heating is a livelihood guarantee project, and the central heating of coal-fired generator sets is the main heating method in cities and towns.

Under the background of the rapid development of new energy and the substantial increase in the proportion of installed capacity, the contradiction between insufficient peak shaving capacity on the power supply side of coal-fired units and new energy consumption continues to deepen. Electric load limitation; power abandonment is serious when heating is maintained, and energy loss is huge.

In order to enhance the peak shaving capability of thermal power, many coal-fired power plants have carried out flexible transformations, mainly including: high back pressure, zero output of low-pressure cylinders, and bypass system transformation. Operation practice shows that these heating operation modes have limited peak shaving capabilities and There are safety problems, for example, the zero output of the low pressure cylinder leads to the damage of the last stage blade of the steam turbine and the flutter of the steam turbine under small volume flow; the use of high and low pressure bypass for heat supply and peak regulation has poor operation reliability of the desuperheater and pressure reducer. , It is easy to be damaged and has problems of failure and poor economy. In order to increase the heating output, some thermal power plants have implemented electric boilers and heat storage systems. There is no technicality in the way of heating, and the investment is too high and the heating economy is too poor. Heat storage and heating are only "peak shifting and filling valleys". the problem of poor adaptability.

At present, the heating peak regulation capacity of coal-fired units is basically limited to the low-pressure cylinder zero output operation mode, which cannot meet the peak heating load demand in extremely cold weather. Only by starting high and low bypass peak regulation for heat supply in thermal power plants can the heating output reach Maximized thermoelectricity can decouple the thermoelectricity completely and realize efficient and adaptive thermoelectricity peak shaving within the range of full heating conditions.

SUMMARY OF THE INVENTION

Based on the above-mentioned prior art, the present invention provides a thermal and electrical peak regulation method for coal-fired units, and the specific technical solutions are as follows:

A thermoelectric peak shaving method for coal-fired units, characterized in that: the thermoelectric peak shaving method for coal-fired units is a thermoelectric peak shaving method based on a high and low side dual ejection system, and the high and low side dual ejection system is a high and low side ejection system. Ejector and its connecting pipeline and regulating gate, reheater and low-by-pass ejector and its connecting pipeline and regulating gate are constituted to achieve complete decoupling of thermoelectricity, maximization of heat supply and deep electrical peak regulation. The specific methods are as follows:

(1) Determine the steam flow at the boiler outlet according to the total thermal and electrical load; according to the thermal load and electrical load, change the opening of the high-pressure bypass valve and the steam inlet valve of the high-pressure cylinder of the turbine, so that the superheated steam is divided into the high-by-pass ejector and the steam turbine. Turbine high pressure cylinder; high bypass ejector outlet steam and high pressure cylinder exhaust steam are combined into reheater;

(2) Adjust the steam flow into the throat of the high-side ejector and the low-pressure cylinder by changing the opening of the low-pressure cylinder steam inlet valve;

(3) By adjusting the opening of the inlet steam regulating valve of the medium pressure cylinder and the low pressure bypass regulating valve, the reheated steam is divided into the middle pressure cylinder and the low bypass ejector of the steam turbine, and the ratio of the inlet steam flow of the middle pressure cylinder and the inlet steam flow of the high pressure cylinder is obtained. The ratio is kept close to the design ratio; the steam at the outlet of the low bypass ejector goes to the heating steam main pipe.

In the above technical scheme, a further technical feature scheme is that: the inlet steam pressure of the high bypass ejector can be supercritical pressure, that is, it can be greater than 22.12MPa; the inlet of the high bypass ejector is connected to the high pressure bypass of the steam turbine. The pipes are connected, the throat of the high side ejector is connected with the exhaust pipe of the medium pressure cylinder, the outlet of the high side ejector is connected with the steam inlet pipe of the reheater; the inlet of the low side ejector is connected with the outlet of the reheater The steam pipeline is connected, the throat of the low bypass ejector is connected with the exhaust steam pipeline of the low pressure cylinder, and the outlet of the low bypass ejector is connected with the heating steam pipeline.

Compared with the prior art, the above technical solution of the present invention has the following advantages.

(1) Coal-fired thermal power plants are completely decoupled from heat and electricity, realize flexible adjustment of heat load and electric load, maximize thermal peak shaving and deep electrical peak shaving, and significantly improve the adaptive thermal peak shaving capability and deep electrical peak shaving capability of units .

(2) The high side ejector can provide long-term stable, safe and efficient heating operation, and ensure the safe operation of the steam turbine during adaptive electrical peak regulation.

(3) The low side ejector can run stably, safely and efficiently for a long time for heating.

Description of drawings

Fig. 1 is a schematic diagram of the thermal and electric peak regulation method of the coal-fired unit of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described below.

As shown in FIG. 1 , the above-mentioned thermal and electrical peak regulation method for coal-fired units provided by the present invention is implemented based on the thermal and electrical peak regulation method of high and low side double injection, and the specific method is as follows:

(1) Install a high-bypass ejector in the high-pressure bypass of the steam turbine, connect the inlet of the high-bypass ejector with the high-pressure bypass pipeline of the turbine, and connect the throat of the high-bypass ejector with the exhaust pipe of the medium-pressure cylinder, Connect the outlet of the high bypass ejector to the inlet steam pipe of the reheater.

(2) Set a low bypass ejector in the low pressure bypass of the steam turbine, connect the inlet of the low bypass ejector with the steam pipe at the outlet of the reheater, connect the throat of the low bypass ejector with the exhaust pipe of the low pressure cylinder, and The outlet of the low bypass ejector is communicated with the heating steam pipeline.

(3) Determine the steam flow at the outlet of the boiler according to the total thermal and electrical load; according to the thermal load and electrical load, adjust the opening of the high-pressure bypass valve 1 and the steam turbine inlet valve 2, so that the superheated steam is divided into the high-bypass ejector and the steam turbine respectively. High pressure cylinder; the steam from the high side ejector and the exhaust steam from the high pressure cylinder are combined into the reheater.

(4) By changing the opening of the low-pressure cylinder inlet steam regulating valve 3, adjust the steam flow into the throat of the high-side ejector and the low-pressure cylinder.

(5) By adjusting the opening of the intermediate pressure cylinder inlet steam regulating valve 4 and the low pressure bypass regulating valve 5, the reheated steam is divided into the steam turbine middle pressure cylinder and the low bypass ejector, and the inlet steam flow of the middle pressure cylinder is the same as that of the high pressure cylinder. The flow ratio is kept close to the design ratio; the steam at the outlet of the low bypass ejector goes to the heating steam main pipe.

In the above-mentioned specific embodiment, the superheated steam at the outlet of the boiler is divided into two paths according to the thermoelectric load: one way enters the high side ejector, ejects the exhaust steam from the medium pressure cylinder, and the other way enters the high pressure cylinder to do work, and the high side ejector exits steam and high pressure. The exhaust steam from the cylinder enters the reheater, part of the reheated steam enters the medium pressure cylinder to do work, and part enters the low side ejector to eject the low pressure cylinder exhaust steam. The ejector thermoelectric peak shaving system makes the thermoelectric flexible regulation, and the thermal peak shaving capability and the deep electric peak shaving capability are significantly enhanced.

Compared with the prior art, the high side ejector is a supercritical pressure and large pressure difference ejector, and the steam pressure at the inlet of the ejector can be greater than 22.12MPa.

This implementation solution solves the problem of thermoelectric coupling of coal-fired thermal power plants. During the heating period in winter, the thermoelectric load can be flexibly adjusted to maximize the heat supply and increase the heat supply output by more than 60%. Electric peak shaving significantly improves the thermal and electrical peak shaving capability and operational adaptability of coal-fired units, and ensures the safety and economy of thermal and electrical peak shaving operations in coal-fired thermal power plants.

Claims (4)

1. A thermoelectric peak regulation method for a coal-fired unit is characterized by comprising the following steps: the thermoelectric peak regulation method of the coal-fired unit is based on a thermoelectric peak regulation method of a high-low side double-injection system, the high-low side double-injection system is composed of a high side injector and a communication pipeline and a regulating valve thereof, a reheater, a low side injector and a communication pipeline and a regulating valve thereof, thermoelectric complete essential decoupling, heat supply maximization and deep electric peak regulation are realized, and the specific method is as follows:

(1) determining the steam flow at the outlet of the boiler according to the total load of the heat and electricity; according to the magnitude of the thermal load and the electrical load, the opening degrees of a high-pressure bypass adjusting valve and a steam inlet adjusting valve of a high-pressure cylinder of the steam turbine are changed, so that superheated steam is shunted and enters a high-pressure bypass ejector and the high-pressure cylinder of the steam turbine respectively; the steam at the outlet of the high-side ejector and the exhaust steam of the high-pressure cylinder are combined and enter a reheater;

(2) regulating the steam flow entering the throat of the high-side ejector and the low-pressure cylinder by changing the opening of a steam inlet regulating valve of the low-pressure cylinder;

(3) the opening degree of the steam inlet regulating valve of the intermediate pressure cylinder and the opening degree of the low-pressure bypass regulating valve are adjusted, so that the reheated steam is shunted to enter the intermediate pressure cylinder and the low-pressure bypass ejector of the steam turbine, and the ratio of the steam inlet flow of the intermediate pressure cylinder to the steam inlet flow of the high pressure cylinder keeps near the design ratio; and the steam at the outlet of the low-side ejector flows to a heat supply steam main pipe.

2. The coal-fired unit thermoelectric peak shaving method of claim 1, characterized in that: the inlet steam pressure of the high side ejector can be supercritical pressure, namely can be more than 22.12 MPa.

3. The coal-fired unit thermoelectric peak shaving method of claim 1, characterized in that: the inlet of the high-side ejector is connected with a high-pressure bypass pipeline of the steam turbine, the throat of the high-side ejector is connected with a medium-pressure cylinder steam exhaust pipeline, and the outlet of the high-side ejector is connected with a reheater steam inlet pipeline.

4. The coal-fired unit thermoelectric peak shaving method of claim 1, characterized in that: the inlet of the low side ejector is connected with the outlet steam pipeline of the reheater, the throat of the low side ejector is connected with the low pressure cylinder steam exhaust pipeline, and the outlet of the low side ejector is connected with the heat supply steam pipeline.

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