CN102519067A - Heating energy saving device with additional back pressure generator for extraction condensing unit and heating energy saving method - Google Patents

Abstract

The invention belongs to the technical field of thermoelectricity, and relates to a heating energy-saving device and an energy-saving method for a condensing extraction unit equipped with a back pressure machine. A back pressure machine is installed between the steam inlets of the heater, the inlet of the steam extraction control valve is connected to the steam extraction port on the turbine side of the connecting pipe of the medium and low pressure cylinder, the outlet of the steam extraction control valve is connected to the inlet of the steam inlet control valve of the back pressure machine and the back pressure machine The inlet of the bypass valve is connected, the outlet of the steam inlet control valve of the back pressure machine is connected to the steam inlet of the back pressure machine, the outlet of the bypass valve of the back pressure machine is connected to the steam inlet of the heat network heater, and the steam exhaust port of the back pressure machine is connected to the heater Inlet connection. In the present invention, by installing a back pressure machine, power recovery is performed on the high-grade heat-supply steam, and the maximum working capacity of the heat-supply flow is reasonably excavated, which solves the problem of not saving energy by using high-grade steam for external heating. It is suitable for efficiency and energy-saving transformation of 300MW or 600MW capacity units of extraction condensing cogeneration in electric power enterprises.

Description

Heat-supply energy-saving device and energy-saving method of adding back pressure machine to condensing unit

technical field

The invention belongs to the technical field of thermoelectricity, and in particular relates to a heating energy-saving device and an energy-saving method for a condensing unit equipped with a back pressure machine.

Background technique

In the "Energy Conservation Law of the People's Republic of China", the state encourages the development of cogeneration of heat and power, centralized heating, and improves the utilization rate of thermal power units. The "National Regulations on the Development of Cogeneration of Heat and Power" also pointed out that cogeneration of heat and power can save energy, improve the environment, improve the quality of heat supply, and increase power supply. Measures are an important part of central heating and a public welfare infrastructure to improve people's quality of life. At present, my country's urban central heating mainly relies on small-scale heating units, but its energy consumption is high and the energy utilization rate is low, so the heating units are developing towards large-scale. Large units with heating load can be divided into two categories, one is the heating unit, that is, the unit is completely designed according to the heating unit; the other is the pure condensing reformed unit, that is, it is transformed from the original pure condensing unit. The steam extraction pressure of a large-scale unit designed as a heat supplier is generally 0.3-0.5 MPa, while the steam turbine of the reformed unit is a designed pure condensing machine, and the pressure series of the medium-pressure cylinder is less than that of the designed heat supplier, resulting in The pressure is limited by the safety of the last-stage vane of the middle sub-cylinder, and there is a lower limit of the ultimate back pressure of the medium-pressure cylinder during rated load operation, and the extraction pressure is as high as 0.8-1.0MPa.

The heat network heater mainly uses the latent heat of vaporization of the heat supply and extraction to heat the water in the heat network, and the change of the heating pressure has little effect on the latent heat of vaporization in a relatively low pressure range. At present, in the operation of my country's heating network, the temperature of supply and return water is generally 130°C/70°C. Considering that there is a 10°C end difference in the heat exchange process, the required saturation temperature of extraction steam is 140°C. This temperature corresponds to The extraction pressure is 0.33MPa. However, during the heating process of large-scale pure condensing heating units, steam with a pressure of 0.8-1.0 MPa is generally used to directly heat the water in the heating network. The mismatch of energy grade will undoubtedly cause a huge loss of available energy. my country's 300MW and 600MW units are generally built in pairs. If the heating network heaters of the two units are connected in series, and the heating network heaters of each stage share the temperature difference between the supply and return water, the heating network water will be heated by the first stage heating network heater. 100°C, also considering the end difference of 10°C, the saturated vapor pressure at this temperature is required to be 0.14MPa. Therefore, there is a need for an energy-saving device and energy-saving method that can reduce the grade of heat supply flow and recover power under the premise of ensuring heat supply, so as to solve the key problem of cogeneration heat supply and energy saving.

Contents of the invention

The purpose of the present invention is to solve the need for an energy-saving device and method that can reduce the grade of the heat supply flow and recover power under the premise of ensuring the heat supply as described in the background technology, and solve the key problem of cogeneration heat supply and energy saving. Provide a heat supply energy-saving device and energy-saving method for a condensing unit equipped with a back pressure machine, the technical scheme of which is:

The heating and energy-saving device of adding back pressure machine to the condensing unit is as follows: in large-scale heating units, the exhaust port 13 of the medium-pressure cylinder of the medium-pressure cylinder 1 is connected to the low-pressure cylinder of the low-pressure cylinder 2 by the connecting pipe 3 of the medium- and low-pressure cylinder. Port 14 is connected, the low-pressure cylinder regulating valve 8 is connected in series in the connecting pipe 3 of the medium and low-pressure cylinder, the exhaust port 15 of the low-pressure cylinder is connected with the steam inlet of the condenser 6, and the heater hot water inlet 19 of the heating network heater 7 is connected with the The heating network return pipe 21 is connected, the heater hot water outlet 20 of the heating network heater 7 is connected to the heating network water supply pipe 22, and the medium and low pressure cylinder connecting pipe 3 before the inlet of the low pressure cylinder regulating valve 8 is connected to the steam turbine side extraction port 5 A back pressure machine 4 is installed between the heater steam inlet 18 of the heat network heater 7, and the inlet of the steam extraction control valve 9 is connected to the steam turbine side extraction port 5 on the medium and low pressure cylinder communication pipe 3, and the steam extraction control valve The outlet of 9 is connected to the inlet of the back pressure machine steam inlet control valve 10 and the back pressure machine bypass valve 11 inlet, the outlet of the back pressure machine steam inlet control valve 10 is connected to the back pressure machine steam inlet 16, and the back pressure machine bypass The outlet of the valve 11 is connected with the heater steam inlet 18 of the heat network heater 7, and the back pressure machine exhaust port 17 is connected with the heater steam inlet 18.

The power of the large heat supply unit is 300MW or 600MW capacity level.

The heat supply and energy saving method of adding a back pressure machine to the condensing unit is as follows:

1) According to the power of the large-scale heating unit and the steam extraction volume of the heating network heater 7 in the middle stage of heating, design the rated steam intake volume of the back pressure machine 4 and the steam intake volume for safe operation;

2) At the initial or final stage of heating, the outdoor ambient temperature is relatively high and the heat load is small. The steam parameters required by the heating network heater 7 cannot meet the requirements for the safe operation of the back pressure machine 4. Turn off the back pressure Machine inlet steam control valve 10, open the back pressure machine bypass valve 11, the steam is drawn out from the middle and low pressure cylinder connecting pipe 3 and directly heats the heating network heater 7;

3) In the middle stage of heating, the outdoor temperature is low, the heating load increases, the steam parameters required by the heating network heater 7 meet the requirements of the safe operation of the back pressure machine 4, and the back pressure machine steam intake control is turned on The valve 10 closes the back pressure machine bypass valve 11, the back pressure machine 4 is put into operation, and the power is recovered.

The installed capacity of thermal power generators in my country accounts for about 10% of the capacity of thermal power generators, and it is becoming more and more large-scale. With the expansion of unit capacity, the waste of energy due to unreasonable extraction pressure is becoming more and more obvious. The waste of units after heating transformation is even more serious. The present invention proposes a solution to this unreasonable heating situation, that is, an innovative design is carried out on the basis of the traditional condensing mode. After the high-grade steam is extracted from the middle and low pressure connecting pipe of the steam turbine, it first passes through a reasonably designed back pressure machine. For power recovery, after the steam is discharged from the back pressure machine, it is introduced into the heating network heater to heat the heating network water. In the process of installing the back pressure machine, install the back pressure machine bypass system to ensure the safe operation of the heating and back pressure machine. At the beginning or end of the heating period, the outdoor ambient temperature is relatively high, the heat load is small, and the operation requirements of the back pressure machine cannot be met, the steam is directly introduced into the heating network heater through the back pressure machine bypass system, which is equivalent to the traditional steam It is directly drawn out from the connecting pipe of the middle and low pressure cylinders and then directly heated by the heating network heater. When entering the middle stage of heating supply, the outdoor temperature is low, the heating load increases, and the required steam parameters meet the operation requirements of the back pressure machine, the back pressure machine will be put into operation to recover the power to meet the external heat supply requirements, and at the same time make the energy saving effect to reach maximum.

The beneficial effect of the present invention is that the present invention solves the problem of energy waste in the operation due to the limitation of the steam extraction position in the heating process of the large-scale extraction condensing cogeneration unit. A back pressure machine is installed to recover power from the high-grade heat-supply steam, reasonably excavate the maximum working capacity of the heat-supply flow, and solve the problem of energy-saving external heating with high-grade steam. It is suitable for efficiency and energy-saving transformation of 300MW or 600MW capacity units of extraction condensing cogeneration in electric power enterprises.

Description of drawings

Fig. 1 is a schematic diagram of a heating energy-saving device equipped with a back pressure machine in a condensing unit;

Fig. 2 is a schematic diagram of the heating mode of the heating unit with a back pressure machine installed;

Figure 3 is a schematic diagram of the heating mode of the pure condensing reformed heating unit with the addition of a back pressure machine.

In the figure, 1--medium pressure cylinder, 2--low pressure cylinder, 3--connecting pipe of medium and low pressure cylinder, 4--back pressure machine, 5--back pressure machine bypass, 6--condenser, 7- -Heating network heater, 8--low pressure cylinder regulating valve, 9-extraction control valve, 10-back pressure machine inlet control valve, 11-back pressure machine bypass valve, 12-medium pressure cylinder inlet Steam port, 13--exhaust port of medium pressure cylinder 13, 14--steam inlet of low-pressure cylinder, 15--exhaust port of low-pressure cylinder, 16--steam inlet of back pressure machine, 17--exhaust steam of back pressure machine 18--heater steam inlet, 19--heater hot water inlet, 20--heater hot water outlet, 21--heating network return pipe, 22--heating network water supply pipe, 23--the first Stage heater, 24--Second stage heater.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples.

Figure 1 is a schematic diagram of a heat supply energy-saving device with a back pressure machine installed in a condensing unit. In a large-scale heating unit (including a designed heating unit and a pure condensing reformed heating unit), the medium-pressure cylinder of the medium-pressure cylinder 1 enters the steam Port 12 is connected to the steam outlet of the high-pressure cylinder, the medium-pressure cylinder exhaust port 13 of the medium-pressure cylinder 1 is connected to the low-pressure cylinder steam inlet 14 of the low-pressure cylinder 2 with the medium-low pressure cylinder connecting pipe 3, and the low-pressure cylinder regulating valve 8 is connected in series In the connecting pipe 3 of the medium and low pressure cylinder, the exhaust port 15 of the low pressure cylinder is connected with the steam inlet of the condenser 6, the heater hot water inlet 19 of the heating network heater 7 is connected with the heating network return pipe 21, and the heating network heater The hot water outlet 20 of the heater 7 is connected to the water supply pipe 22 of the heating network, and the steam inlet of the steam turbine side extraction port 5 on the middle and low pressure cylinder connecting pipe 3 before the inlet of the low pressure cylinder regulating valve 8 is connected to the heater inlet of the heating network heater 7 A back pressure machine 4 is installed between the ports 18, the inlet of the steam extraction control valve 9 is connected to the steam extraction port 5 on the turbine side on the medium and low pressure cylinder communication pipe 3, and the outlet of the steam extraction control valve 9 is connected to the steam inlet control valve of the back pressure machine The inlet of 10 is connected to the inlet of back pressure machine bypass valve 11, the outlet of back pressure machine steam inlet control valve 10 is connected to back pressure machine steam inlet 16, the outlet of back pressure machine bypass valve 11 is connected to the outlet of heat network heater 7 The heater steam inlet 18 is connected, and the back pressure machine exhaust port 17 is connected with the heater steam inlet 18.

In my country, large-capacity heating units such as 300MW and 600MW capacity units are generally built in pairs. Considering the two units comprehensively, two heating network heaters are set up in series mode, and the two-stage heating network heaters are equally divided into heating network water. The temperature rise of the first-stage heating network heater is heated from 70°C to 100°C, and the water temperature of the second-stage heating network heater is heated from 100°C to 130°C. Therefore, the steam turbine extraction pressure required by the two heat network heaters is different. Different solutions have been obtained according to the pressure differences of the middle and low pressure sub-cylinders of the designed heating unit and the pure condensing heating reformed unit.

Embodiment 1 is the heat supply mode of the heating unit with a back pressure machine installed. As shown in Figure 2, the unit I is equipped with a back pressure machine 4, the sub-cylinder pressure of the middle and low pressure cylinders is about 0.3-0.5 MPa, and the saturation temperature is 133.53 ~151.84°C, can be directly used as the heat source of the second-stage heating network heater 24 to heat the heating network water, but it is unreasonable to use steam with a pressure of 0.3-0.5MPa to heat the heating network water in the first-stage heating network heater 23 Therefore, after the steam is extracted from the middle and low pressure cylinder connecting pipe 3, it passes through a back pressure machine 4 to utilize the high-grade steam first, and after the steam pressure is reduced to 0.14MP, it is introduced into the first-stage heat network heater 23 to Hot grid water for heating. The heat network heater drains water into the deaerator.

Embodiment 2 is the heat supply mode of the pure condensing reform heating unit with the addition of a back pressure machine. As shown in Figure 3, for the pure condensing reform heating unit, both unit I and unit II are equipped with a back pressure machine 4. The sub-cylinder pressure of the low-pressure cylinder is relatively high, about 0.8-1.0MPa, which is far higher than the saturation pressure required by the heating network water in the second-stage heater 24, so two back pressure machines 4 need to be installed in the first Before the first stage heater 23 and the second stage heater 24, the back pressure machine 4 before the second stage heater 24 reduces the extraction pressure from 0.8 to 1.0MPa to 0.33MPa and then introduces the second stage heater 24 to the heat network The water is heated. The back pressure machine 4 in front of the first-stage heater 23 reduces the extraction pressure from 0.8 to 1.0 MPa to 0.14 MPa, and then introduces a first-stage heat network heater to heat the heat network water. The drains of the two heaters are introduced into the deaerators of their respective units.

The adjustment of the back pressure machine system is as follows: in the early stage of heating, the ambient temperature is relatively high, and the required water temperature of the heating network is relatively low. , when a small amount of steam cannot meet the operation requirements of the back pressure machine, it can be directly introduced into the heating network heater through the bypass system of the back pressure machine to heat the water in the heating network; When increasing, to meet the operation requirements of the back pressure machine and to ensure the heat supply, close the bypass to let the steam recover the power through the back pressure machine and then introduce it into the heating network heater; When it is too small to meet the operation requirements of the back pressure machine, the back pressure machine will be disabled, and the steam will enter the heat network heater from the bypass until the heating cycle is over and the unit will run in pure condensation.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (3)

1. take out the heating energy-saving device that unit with fixed attention installs the back pressure machine additional for one kind; In large-scale heat supply unit; The intermediate pressure cylinder steam drain (13) of intermediate pressure cylinder (1) was connected with the low pressure (LP) cylinder air intake (14) of low pressure (LP) cylinder (2) with mesolow cylinder communicating pipe (3); Low pressure (LP) cylinder control valve (8) was serially connected in mesolow cylinder communicating pipe (3); Low pressure (LP) cylinder steam drain (15) is connected with the air intake of condenser (6); The heater hot water inlet (19) of heat exchangers for district heating (7) is connected with heat supply network return pipe (21), and the heater hot water outlet (20) of heat exchangers for district heating (7) is connected with heat supply network feed pipe (22), it is characterized in that; Install back pressure machine (4) additional between the heater air intake (18) of steam turbine side extraction opening (5) and heat exchangers for district heating (7) on mesolow cylinder communicating pipe (3) before the import of low pressure (LP) cylinder control valve (8); The import of extraction control valve (9) is connected with steamer pusher side extraction opening (5) on mesolow cylinder communicating pipe (3), and import is connected with back pressure machine bypass valve (11) in the import of the outlet of extraction control valve (9) and back pressure machine admission control valve (10), and the outlet of back pressure machine admission control valve (10) is connected with back pressure machine air intake (16); The outlet of back pressure machine bypass valve (11) is connected with the heater air intake (18) of heat exchangers for district heating (7), and back pressure machine steam drain (17) is connected with heater air intake (18).

2. according to claim 1 taking out coagulated the heating energy-saving device that unit installs the back pressure machine additional, it is characterized in that the power of said large-scale heat supply unit is 300MW or 600MW capacitance grade.

3. take out the heating energy-saving method that unit with fixed attention installs the back pressure machine additional for one kind, it is characterized in that, uses as claimed in claim 2 taking out to coagulate the power-economizing method that unit installs the heating energy-saving device of back pressure machine additional and be:

1) according to the amount of drawing gas of the power and the heat supply heat exchangers for district heating in mid-term (7) of large-scale heat supply unit, the specified throttle flow and the safe operation throttle flow of design back pressure machine (4);

2) in heat supply initial stage or latter stage; Outdoor environment temperature is higher relatively; Thermic load is less, and back pressure machine admission control valve (10) is closed in the requirement that the required steam parameter of heat exchangers for district heating (7) does not reach the safe operation throttle flow of back pressure machine (4); Open back pressure machine bypass valve (11), steam is therefrom extracted directly heating heat exchangers for district heating (7) of back low pressure (LP) cylinder communicating pipe (3) out;

3) getting into heat supply mid-term; Outdoor temperature is lower, and heating demand increases, and the required steam parameter of heat exchangers for district heating (7) reaches the requirement of the safe operation throttle flow of back pressure machine (4); Open back pressure machine admission control valve (10); Close back pressure machine bypass valve (11), back pressure machine (4) puts into operation, reclaims power.

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