CN205840930U - A kind of high back pressure little steam turbine heating extraction for heat supply system - Google Patents

Abstract

A high back pressure small steam turbine heating extraction steam heating supply system, mainly including medium pressure cylinder, low pressure cylinder, high back pressure small steam turbine, peak heater, front heater, asynchronous generator, drain pump, electric gate valve, electric adjustment Valves, electric butterfly valves, circulating water pumps, heating network water supply pipelines, and heating network return pipelines are mainly for subcritical 300MW and above steam turbine heating extraction and heating supply renovation projects. Among them, the high-quality steam extracted from the low-pressure connecting pipe is After the high back pressure small steam turbine does work, the steam depressurizes and enters the front heater to heat the circulating water of the heating network. During the heating period, try to keep the high back pressure small steam turbine running at full load, and meet the adjustment requirements of the heating load change through the adjustment of the peak heater. The circulating water of the heating network enters the pre-heater and the peak heater in sequence through the heating network return water pipeline to be heated and then supplied to the heat users through the heating network water supply pipeline. The utility model increases the power generation capacity of the unit, realizes energy cascade utilization, and has good economy and operation flexibility.

Description

A high back pressure small turbine heating extraction steam heating system

technical field

The utility model belongs to the technical field of energy-saving of thermal power plants, and is directly applied to the renovation project of subcritical 300MW and above-capacity steam turbines for heating extraction and heating supply, so as to realize cogeneration of heat and power and improve the cycle efficiency of the unit.

Background technique

At present, the main domestic heating extraction and heat supply transformation scheme is to drill holes in the medium and low pressure connecting pipes of the steam turbine, lead the medium pressure cylinder exhaust steam into the heating network heater to heat the circulating water of the heating network to achieve external heating. The transformation plan is simple to implement for steam turbines with a capacity of 200MW and below, and the initial investment is small. There are already a large number of mature cases in China. High (above 0.7Mpa, far greater than the steam pressure 0.2-0.3MPa required by the heating network heater to heat the circulating water of the heating network). The external heating is realized by heating the circulating water of the heating network, which wastes high-quality steam to a certain extent.

Contents of the invention

The utility model provides a high-back pressure small steam turbine heating and steam extraction heating system. The system can meet the needs of heating, steam extraction and heating while generating a certain amount of electricity, and solves the problem of subcritical 300MW and above capacity steam turbines. The problem of waste of high-quality steam caused by direct external heating after steam decompression.

The technical scheme adopted by the utility model to solve the technical problem is: a heating system with high back pressure small steam turbine, which mainly includes medium pressure cylinder, low pressure cylinder, high back pressure small steam turbine, peak heater, front heating Devices, asynchronous generators, drain pumps, electric gate valves, electric control valves, electric butterfly valves, circulating water pumps, heating network water supply pipelines, and heating network return water pipelines. Both the front heater and the peak heater are surface heaters, which are divided into two parts: the steam side and the water side. The steam side corresponds to the steam inlet and the drain outlet, and the water side corresponds to the water side inlet and the water side outlet. The exhaust port of the medium-pressure cylinder is provided with two branches, one of which is connected to the inlet of the low-pressure cylinder, and an electric butterfly valve is installed on the branch, and the steam intake of the low-pressure cylinder is controlled by the opening of the electric butterfly valve to realize Extraction pressure adjustment function; when the heating period is over, the electric butterfly valve is fully opened, and the unit returns to pure condensation operation; the other branch is the heating steam pipeline, which is divided into two branches, One branch is connected with the small steam turbine with high back pressure. The exhaust steam of the medium pressure cylinder is used as the driving steam source of the small steam turbine with high back pressure to drive the asynchronous generator connected with the small steam turbine with high back pressure to generate electricity. The exhaust steam of the small steam turbine with high back pressure enters the front The inlet of the steam side of the heater; the other branch is connected with the inlet of the steam side of the peak heater. The water side of the pre-heater and the water side of the peak heater are connected in series, the pre-heater heats the circulating water of the heating network sent by the water supply pipeline of the heating network from 70 degrees to 95 degrees, and the peak heater heats the circulating water of the heating network After heating from 95 degrees to 130 degrees or the temperature required by the heating network, it will be supplied to heat users. During the whole heating period, try to keep the small steam turbine with high back pressure running at full load, so that the small steam turbine with high back pressure has high operating economy. The peak heater also has an adjustment function, and when the heat load changes, the temperature of the circulating water supply of the heating network is adjusted through the peak heater. The peak heater is a full-capacity surface heater, which can bear 100% of the heating load of the heating network system, that is, it can directly heat the circulating water of the heating network from 70°C to 130°C or The temperature required by the heating network.

The drainage of the pre-heater and the peak heater is pressurized by the drainage pump and then returned to the condensate system.

An electric regulating valve is installed on the heating steam pipeline. When the heating period is over, the electric regulating valve is closed, and the unit returns to pure condensing operation.

An electric gate valve is installed at the steam inlet of the small steam turbine with high back pressure. When the small steam turbine with high back pressure fails or needs to be shut down, the electric gate valve is closed.

An electric gate valve is installed on the pipeline connecting the return water pipeline of the heating network to the water side outlet of the front heater. When the high back pressure small steam turbine is running normally, the electric gate valve is closed, and when the high back pressure small steam turbine is out of operation, the electric gate valve is opened. At this time, the circulating water of the heating network does not enter the front heater, but directly enters the peak heater for heating.

The beneficial effect of the utility model is that, by adding a small steam turbine with high back pressure in the heating reformation system, steam extraction with a higher parameter is used to generate electricity, and after the parameter is reduced, a front heater is introduced to heat the circulating water of the heating network; the peak heating The setting of the device ensures that the heating system can still meet the heat load requirements when the heat load changes or when the small steam turbine with high back pressure is out of service. The utility model improves the power generation capacity of the unit, realizes energy cascade utilization, and has good economy and operation flexibility.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Fig. 1 is a structural schematic diagram of the utility model.

In the figure 1. Medium pressure cylinder, 2. Low pressure cylinder, 3. High back pressure small steam turbine, 4. Asynchronous generator, 5. Front heater, 6. Peak heater, 7. Drain pump, 8. Electric butterfly valve, 9. Electric gate valve, 10. Circulating water pump, 11. Electric regulating valve, 12. Heat network water supply pipeline, 13. Heat network return water pipeline, 14. Electric gate valve.

detailed description

In the embodiment shown in Figure 1, there are two branches at the exhaust port of the medium-pressure cylinder (1), one branch is connected to the inlet of the low-pressure cylinder (2), and an electric motor is installed on the branch. Butterfly valve (8); the other branch is divided into two branches, one branch is connected with the high back pressure small steam turbine (3), and the high back pressure small steam turbine (3) is connected with the asynchronous generator (4); the other branch is connected with the peak The steam side inlet of the heater (6) is connected. The exhaust steam of the high back pressure small turbine (3) enters the steam side inlet of the front heater (5). The circulating water of the heating network enters the front heater (5) and the peak heater (6) sequentially through the return water pipeline (13) of the heating network, and the circulating water of the heating network coming out of the water side outlet of the peak heater (6) passes through the heating network The water supply pipeline (12) supplies heat consumers. Shut down the small steam turbine (3) with high back pressure during the non-heating period, close the electric regulating valve (11), electric gate valve (14), electric gate valve (9), fully open the electric butterfly valve (8), and the unit returns to pure condensing operation . During the heating period, when the high back pressure small steam turbine (3) fails, it is necessary to remove the high back pressure small steam turbine (3) from the system. At this time, the electric gate valve (14) is closed, the electric gate valve (9) is opened, and the peak heater (6) Directly heat the circulating water of the heating network from 70°C to 130°C or the temperature required by the heating network.

The drainage of the front heater (5) and the peak heater (6) is pressurized by the drainage pump (7) and then returned to the condensate system.

Specifically, this utility model is mainly aimed at the subcritical 300MW and above-capacity steam turbine heating extraction and heat supply renovation project, in which the high-quality steam extracted from the low-pressure connecting pipe first passes through a small steam turbine with high back pressure to do work, and the steam enters after depressurization The pre-heater heats the circulating water of the heating network. In order to ensure the high thermal efficiency of the small steam turbine with high back pressure, during the heating period, try to keep the small steam turbine with high back pressure running at full load, and meet the adjustment requirements of the heating load change through the adjustment of the peak heater. The drainage of the front heater and the peak heater enters the condensate system after being pressurized by the drainage pump. The circulating water of the heating network enters the pre-heater and the peak heater in turn through the return water pipeline of the heating network, and is supplied to the heat user through the water supply pipeline of the heating network after being heated. During the heating operation of the steam turbine, when the heat load is constant, the electrical power of the steam turbine has a minimum limit value to ensure that the steam turbine has sufficient steam intake, and then the low-pressure cylinder has sufficient steam intake to ensure the safety of the low-pressure cylinder operation. According to the different steam turbine capacity, steam extraction parameters and flow rate, the high back pressure small steam turbine can choose a model with a rated power of 5MW-12MW, and the number is 1-2.

Claims (1)

1. A high back pressure small steam turbine heating extraction steam heating supply system, mainly including medium pressure cylinder, low pressure cylinder, high back pressure small steam turbine, peak heater, front heater, asynchronous generator, drain pump, electric gate valve, Electric regulating valve, electric butterfly valve, circulating water pump, heating network water supply pipeline, heating network return water pipeline, characterized in that: the exhaust port of the medium pressure cylinder is provided with two branches, one branch and the inlet of the low pressure cylinder An electric butterfly valve is installed on this branch; the other branch is a heating steam pipeline, which is divided into two branches, one branch is connected with a small steam turbine with high back pressure, and the small steam turbine with high back pressure It is connected with the asynchronous generator, and the exhaust steam of the small steam turbine with high back pressure enters the steam side inlet of the preheater; the other branch is connected with the steam side inlet of the peak heater, and the preheater and the peak heater are both surface type The heater is divided into two parts: the steam side and the water side. The steam side corresponds to the steam inlet and the drain outlet, and the drain outlet is equipped with a drain pump; the water side corresponds to the water side inlet and the water side outlet. The water side of the pre-heater and the peak heating The water side of the heater is connected in series, an electric regulating valve is installed on the heating steam pipeline, and an electric gate valve is installed on the steam inlet of the small steam turbine with high back pressure and the return water pipeline of the heating network connected to the outlet of the water side of the front heater.