CN108534126A - It is a kind of with pressure matcher machine stove waste heat coupling utilize system - Google Patents

Abstract

The present invention relates to a kind of, and the machine stove waste heat coupling with pressure matcher utilizes system, including turbine low pressure cylinder, pressure matcher, steam air heater, air preheater and low-level (stack-gas) economizer；Pressure matcher input terminal is connect by the steam discharge extraction line of low pressure (LP) cylinder pump-line and connection low pressure (LP) cylinder discharge duct with turbine low pressure cylinder, for under the driving that steam turbine low-pressure is evacuated, steam turbine low-pressure exhaust is extracted, steam of the pressure between low-pressure pumping steam and low pressure steam discharge is generated；The input terminal of steam air heater is connect by jet chimney with pressure matcher output end, output end is connect with air preheater, for being preheated to the cold wind, the secondary cold wind that enter steam air heater by steam, and a cold wind, the secondary cold wind after preheating are exported to air preheater；Air preheater is connect with low-level (stack-gas) economizer, and low-level (stack-gas) economizer is connected with circulating water inlet road and circulating water outlet pipe road.The present invention solves the problems, such as Steam Turbine exhaust steam waste heat utilization.

Description

A coupled utilization system of machine furnace waste heat with a pressure matcher

technical field

The invention belongs to the technical field of thermal power generation, and in particular relates to a coupling utilization system for residual heat of a machine furnace with a pressure matching device.

Background technique

For thermal power units, the exhaust steam of the steam turbine takes away a huge amount of energy. The exhaust temperature of the wet-cooled unit can reach 30-50°C, and the exhaust temperature of the air-cooled unit can reach 60-70°C. Effective recovery of waste heat from steam turbine exhaust is a difficult problem, mainly manifested in two aspects: first, the energy level of steam turbine exhaust is not high, and the space for low-temperature exhaust steam is small; second, the specific volume of steam turbine exhaust is extremely large If the exhaust steam is directly used for heat exchange, a large heat exchanger and related pipelines need to be designed, which will increase equipment investment and operating costs, and greatly reduce the energy-saving benefits.

Contents of the invention

The object of the present invention is to provide a coupling utilization system of waste heat of a machine furnace with a pressure matching device, so as to solve the problem of utilization of waste heat of exhaust steam of a steam turbine unit.

The invention provides a boiler waste heat coupling utilization system with a pressure matching device, which includes a steam turbine low-pressure cylinder, a pressure matching device, an air heater, an air preheater and a low-temperature economizer;

The input end of the pressure matcher is connected to the low-pressure cylinder of the steam turbine through the suction pipe of the low-pressure cylinder and the exhaust steam extraction pipe connected to the exhaust pipe of the low-pressure cylinder. The steam extraction pipeline extracts the low-pressure exhaust of the steam turbine to generate steam whose pressure is between the low-pressure extraction steam and the low-pressure exhaust steam;

The input end of the air heater is connected to the output end of the pressure matcher through the steam pipe, and the output end of the air heater is connected to the air preheater; The secondary cold air is preheated, and the preheated primary cold air and secondary cold air are output to the air preheater to absorb the heat of the flue gas;

The air preheater is connected with the low-temperature economizer, and the low-temperature economizer is connected with a circulating water inlet pipe and a circulating water outlet pipe.

Further, the low-pressure cylinder air extraction pipeline includes a first low-pressure cylinder air extraction pipeline and a second low-pressure cylinder air extraction pipeline.

Further, the first low-pressure cylinder air extraction pipeline and the second low-pressure cylinder air extraction pipeline are respectively provided with a first valve and a second valve whose opening can be adjusted.

Further, the exhaust steam extraction pipeline is provided with a third valve whose opening can be adjusted.

Further, the circulating water inlet pipe is provided with a fourth valve whose opening can be adjusted.

Further, the system also includes an energy-saving index calculation module for calculating the energy-saving energy index of the unit of the boiler waste heat coupling utilization system, and the opening degrees of the first valve, the second valve, the third valve, and the fourth valve are based on the calculated The energy saving index of the unit and the principle of maximizing the overall economic benefits of the unit are set.

With the above scheme, the following technical effects have been produced through the coupling utilization system of machine furnace waste heat with pressure matching device:

1. Use the pressure matcher to reduce the specific volume of the exhaust steam of the steam turbine, so that the waste heat of the exhaust steam of the steam turbine, which is difficult to be used directly, can be recovered.

2. The recovered waste heat of unit exhaust steam can be used to offset part of the use of boiler flue gas, which increases the heat release of flue gas in the low-temperature economizer system, increases the heat absorption of condensate water, and reduces the use of extraction steam in the heat recovery system.

3. For the conventional system, the lower the atmospheric temperature, the more heat input is required for the steam-gas-steam-gas heater to heat the cold air, the greater the steam extraction consumption of the steam turbine, and the more obvious the decline in the economic benefits of the unit. However, for the present invention, the lower the external steam temperature, the larger the heat exchange temperature difference between the exhaust steam of the turbine and the cold air, the higher the heat exchange efficiency, and the greater the waste heat gain of the machine furnace coupling.

4. Due to the cooling of part of the exhaust steam of the steam turbine in the steam-gas-steam-gas heater, the original circulating water (wet cooling unit) consumption is reduced, and the corresponding circulating water pump power consumption is reduced.

Description of drawings

Fig. 1 is a structural schematic diagram of a coupling utilization system for residual heat of a machine furnace with a pressure matching device according to the present invention.

Labels in the figure:

1-primary cold air; 2-secondary cold air; 3-steam-gas steam-gas heater; 4-air preheater; 5-low temperature economizer; 6-flue gas to dust collector; 7-circulating water Water pipeline; 8-circulating water outlet pipeline; 9-turbine low-pressure cylinder; 10-low-pressure cylinder exhaust pipeline; 12-pressure matching device; 13-steam pipeline; 14-drainage pipeline; 16-second low-pressure cylinder air extraction pipeline; 17-exhaust steam extraction pipeline.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in Figure 1, this embodiment provides a system for coupling utilization of waste heat from a boiler with a pressure matching device, including a steam turbine low-pressure cylinder 9, a pressure matching device 12, a steam-gas steam-gas heater 3, an air preheating device 4 and low temperature economizer 5. The input end of the pressure matching device 12 is connected to the steam turbine low-pressure cylinder 9 through the low-pressure cylinder extraction pipeline and the exhaust steam extraction pipeline 17 connected to the low-pressure cylinder exhaust pipeline 10, and is used to drive the low-pressure extraction of the steam turbine output from the low-pressure cylinder extraction pipeline. Next, the low-pressure exhaust gas of the steam turbine is extracted through the exhaust steam extraction pipeline 17 to generate steam with a stable pressure between the low-pressure extraction steam and the low-pressure exhaust steam.

The input end of the steam-gas steam-gas heater 3 is connected to the output end of the pressure matcher 12 through the steam pipeline 13, and the output end of the steam-gas steam-gas heater 3 is connected to the air preheater 4; the steam-gas The steam-gas heater 3 is used for preheating the primary cold wind and the secondary cold wind entering the steam-gas steam-gas heater 3 by the steam output from the steam pipe 13, and the preheated primary cold wind, secondary The cold air is output to the air preheater 4 to absorb the heat of the flue gas. The air preheater 4 is connected to a low-temperature economizer 5 , and the low-temperature economizer 5 is connected to a circulating water inlet pipe 7 and a circulating water outlet pipe 8 .

The boiler waste heat coupling utilization system with a pressure matching device provided in this embodiment uses the low-pressure steam extraction of the steam turbine to drive the pressure matching device 12 to extract the low-pressure exhaust steam of the steam turbine, and generates steam with a pressure between the low-pressure extraction steam and the exhaust steam that enters the steam- The air heater 3 preheats the primary cold air 1 and the secondary cold air 2 of the boiler, and the preheated primary and secondary cold air continue to enter the air preheater 4 to absorb the heat of the flue gas.

Due to the heat input of the exhaust steam of the steam turbine, the heat release of the flue gas in the air preheater 4 is reduced, and the flue gas carries more heat into the low-temperature economizer 5 to release heat to feed the circulating water, and the circulating water after absorbing heat The effluent returns to the steam turbine recuperation system, reducing the steam extraction volume of the recuperation system, and the saved extraction steam continues to work in the steam turbine unit, realizing energy cascade utilization and improving the overall efficiency of the unit. .

The function of the low-temperature economizer 5 in the system is to use the waste heat of the flue gas at the outlet of the air preheater 4 to heat part of the condensed water extracted from the low-temperature condensed water system (through the circulating water inlet pipe 7), and the heated condensed water passes through the circulation The water outlet pipeline 8 returns to the steam turbine recuperation system to continue absorbing heat.

In this embodiment, the low-pressure cylinder air extraction pipeline includes a first low-pressure cylinder air extraction pipeline 15 and a second low-pressure cylinder air extraction pipeline 16, through which the first low-pressure cylinder air extraction pipeline 15 and the second low-pressure cylinder air extraction pipeline 16 can make The steam turbine low-pressure extraction is extracted from different extraction pipes, which is convenient for control and maintenance.

In this embodiment, the first low-pressure cylinder air extraction pipeline 15, the second low-pressure cylinder air extraction pipeline 16, the exhaust steam extraction pipeline 17, and the circulating water inlet pipeline 7 are all provided with valves, through which the opening can be adjusted. , under different unit loads, the boiler waste heat coupling utilization system can be jointly controlled according to parameters such as the external cold air temperature, steam turbine exhaust temperature and exhaust steam volume.

In this embodiment, a first valve and a second valve are respectively provided on the first low-pressure cylinder exhaust pipeline 15 and the second low-pressure cylinder exhaust pipeline 16, and the valve openings of different extraction pipelines are adjusted according to different load conditions of the unit. Control the steam extraction share to ensure the safe and economical operation of the unit.

In this embodiment, the exhaust steam extraction pipe 17 is provided with a third valve whose opening can be adjusted. By adjusting the opening of the third valve, the amount of exhaust steam entering the pressure matching device 12 is controlled, and the remaining exhaust steam of the steam turbine enters the unit. Existing exhaust cooling system.

In this embodiment, the circulating water inlet pipe 7 is provided with a fourth valve whose opening can be adjusted, and the amount of condensed water drawn is controlled by adjusting the opening of the fourth valve.

In this embodiment, the system also includes a calculation module for calculating the energy saving energy index of the unit of the system for coupling and utilization of waste heat from boilers and boilers. The opening degrees of the first valve, the second valve, the third valve, and the fourth valve are based on The calculated unit energy saving index and the principle of maximizing the overall economic benefits of the unit are set.

The calculation module of energy-saving energy index calculates the energy-saving energy index of the system based on the thermal economic model of the entire unit based on the steam turbine-boiler, and sets the waste heat coupling of the turbine and boiler according to the principle of maximizing the overall economic benefits of the unit on the basis of the safe operation of the unit. Utilize the opening of the valves on the first low-pressure cylinder exhaust pipeline 15, the second low-pressure cylinder exhaust pipeline 16, the exhaust steam extraction pipeline 17, and the circulating water inlet pipeline 7 to control and adjust the low-pressure extraction steam consumption, steam turbine exhaust Steam consumption, condensate extraction, etc.

It should be noted that the energy saving effect of the present invention is different in wet cooling units and air cooling units. Theoretically, the higher the exhaust steam temperature of the steam turbine unit, the greater the energy contained in the exhaust steam, and the more obvious the energy-saving effect of the system for coupling and utilizing waste heat of the machine and boiler of the present invention. At the same time, the area where the air-cooled unit is used is generally in the arid and cold north, where the temperature of the primary and secondary air in winter is very low, and the heat exchange temperature difference in the steam-gas steam-gas heater is large, and the effect of the heat exchanger is obvious.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the technical principle of the present invention. and modifications, these improvements and modifications should also be considered as the protection scope of the present invention.

Claims (6)

1. A coupling utilization system for waste heat of a machine furnace with a pressure matching device, characterized in that it includes a steam turbine low-pressure cylinder, a pressure matching device, a heater, an air preheater and a low-temperature economizer; The input end of the pressure matcher is connected to the low-pressure cylinder of the steam turbine through the low-pressure cylinder suction pipeline and the exhaust steam extraction pipeline connected to the exhaust pipeline of the low-pressure cylinder, and is used for the low-pressure suction of the steam turbine output from the low-pressure cylinder suction pipeline. Driven by the exhaust steam extraction pipeline, the low-pressure exhaust gas of the steam turbine is extracted to generate steam whose pressure is between the low-pressure extraction steam and the low-pressure exhaust steam; The input end of the air heater is connected to the output end of the pressure matcher through a steam pipeline, and the output end of the air heater is connected to the air preheater; the air heater is used to output through the steam pipeline The steam preheats the primary cold air and secondary cold air entering the heater, and outputs the preheated primary cold air and secondary cold air to the air preheater to absorb the heat of flue gas; The air preheater is connected with the low-temperature economizer, and the low-temperature economizer is connected with a circulating water inlet pipe and a circulating water outlet pipe. 2. A system for coupling utilization of residual heat of a machine furnace with a pressure matching device according to claim 1, wherein the low-pressure cylinder air extraction pipeline includes a first low-pressure cylinder air extraction pipeline and a second low-pressure cylinder air extraction pipeline . 3. A system for coupling utilization of residual heat of a machine furnace with a pressure matching device according to claim 2, wherein the first low-pressure cylinder air extraction pipeline and the second low-pressure cylinder air extraction pipeline are respectively provided with adjustable openings. degree of the first valve and the second valve. 4. A coupled utilization system for waste heat of a machine furnace with a pressure matching device according to claim 3, wherein the exhaust steam extraction pipeline is provided with a third valve whose opening can be adjusted. 5 . The coupled utilization system for residual heat of a machine furnace with a pressure matching device according to claim 4 , wherein the circulating water inlet pipe is provided with a fourth valve whose opening can be adjusted. 6 . 6. A system for coupled utilization of machine-furnace waste heat with a pressure matching device according to claim 5, further comprising an energy-saving index calculation module for calculating energy-saving index of units of the machine-furnace waste heat coupled utilization system , the openings of the first valve, the second valve, the third valve and the fourth valve are set based on the calculated unit energy saving index and the principle of maximizing the overall economic benefits of the unit.