Energy gradient utilization system for combined heat and power generation of heat supply network initial station heat supply steam differential pressure power generation

Abstract

The invention discloses an energy gradient utilization system for combined heat and power generation of heat supply steam pressure difference power generation of a heat supply network initial station, which is characterized in that heat supply steam passes through a heat supply steam main pipe and flows to a high-temperature heat supply network initial station heat exchanger and at least one low-temperature heat supply network initial station heat exchanger along a heat supply steam branch pipeline; heat supply steam entering the high-temperature heat supply network head station heat exchanger from the heat supply steam main pipe along the heat supply steam branch pipelines generally does not need to pass through a pressure difference power generation device and directly enters the high-temperature heat supply network head station heat exchanger to heat circulating water, and heat supply steam passing through other heat supply steam branch pipelines passes through at least one steam pressure difference power generation device to become reduced pressure steam. And the circulating water enters a low-temperature heat supply network initial station heat exchanger, and the circulating water is heated by at least one low-temperature heat supply network initial station heater and at least one high-temperature heat supply network initial station heater in sequence from low temperature to high temperature, so that the required heating temperature is achieved. The problem that in the prior art, due to the fact that energy and temperature gradient between heat supply steam and a heating medium are too large, work capacity is wasted can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steam heating of the first station of a heat supply network, and particularly relates to an energy gradient utilization system for power generation and heat-electricity cogeneration of steam pressure difference of the first station of a heat supply network. BACKGROUND

[0002] In recent years, with the intensive use of energy and environmental protection requirements, and the increase of the "three combined" of power plant, the city heating more and more use of steam provided by the power plant to central heating. Its heating economy, small pollution to the environment, also brings additional economic benefits to the power plant. The heat supply network station in the heating system of the power plant as the heat source is very important. It will use the steam extraction of steam turbine to heat supply, heat release condensation, and heat exchange with the heating cycle water. If the heating pipe network is compared to the "blood vessels" of the whole heating system, then the heat supply network station is equivalent to the "heart" of the system, which provides a steady stream of heat for the whole heating system. The source of heat comes from the steam extraction of steam turbine, or other boilers, waste heat boiler, etc. Taking the steam extraction of low pressure cylinder in steam turbine as an example, the pressure of the steam extraction is usually between 0.25-1.2Mpa, and the temperature of the heated heat supply network cycle water entering the heat supply network station is 50-70℃, which is heated to 90-130℃ in the heat supply network station. Among them, the typical requirement is from 70℃ to 130℃. Then it is sent to the city to participate in direct or indirect heat exchange, and the heat is sent to thousands of households. We know that the heat energy utilization of steam should follow the principle of energy grade utilization, that is, high energy high use, low energy low use, and temperature and pressure matching. In the process of heat exchange in the heat supply network station, when the superheated steam with an absolute pressure of 0.3Mpa is used as the heat source, the saturation temperature of the steam is about 133℃, and the saturation point phase change is the main steam heat release section, which can heat the cycle water to 130 degrees. However, we notice that the initial temperature of the cycle water entering the heat supply heater is only 70℃, or even 50℃, which forms a certain temperature gradient between the saturation temperature of the steam and the heated cycle water. The saturation pressure of the steam corresponding to 70℃ is about 0.031Mpa (absolute pressure). For example: when we heat the heat supply network cycle water from 70℃ to 80℃, theoretically without considering the cold and hot end difference of the heat exchanger, the saturation steam temperature corresponding to 80℃ is 0.048Mpa, that is, 0.048Mpa steam can be used to heat 70℃ water to 80℃. Then, in the temperature gradient of 70℃ to 80℃, the steam pressure for heating the cycle water is 0.048Mpa, which can be reduced to 0.048Mpa from 0.3Mpa (take the low value in 0.3-0.8Mpa) of the steam extraction of steam turbine through work, and the intermediate 0.252Mpa pressure is used to generate electricity, so as to realize the gradient utilization of energy, high energy high use, low energy low use, and gradient utilization. The smaller the gradient is, the more sufficient the utilization is, and the full use of steam work and heat supply is realized. SUMMARY

[0003] The purpose of the present application is to provide a heat supply network station heating steam pressure difference power cogeneration energy gradient utilization system, which can solve the technical problems of waste of work capacity due to large energy and temperature gradient between heating steam and heating medium in the prior art.

[0004] The technical solution of the present application is: The energy gradient utilization system of heat supply steam pressure difference power generation and heat and power cogeneration in the first station of the heat supply network is characterized in that it comprises: heat supply steam, heat supply steam main pipe, heat supply steam branch pipeline, pressure difference power generation device, reduced pressure steam, high-temperature heat supply network first station heat exchanger, low-temperature heat supply network first station heat exchanger, heat supply network circulating water, and steam drainage; wherein: the heat supply steam flows to the high-temperature heat supply network first station heat exchanger and at least one low-temperature heat supply network first station heat exchanger along the heat supply steam branch pipeline through the heat supply steam main pipe; and the heat supply steam entering the high-temperature heat supply network first station heat exchanger from the heat supply steam main pipe along the heat supply steam branch pipeline directly enters the high-temperature heat supply network first station heat exchanger without passing through the pressure difference power generation device to heat the circulating water, or passes through the pressure difference power generation device to heat the circulating water; the heat supply steam passing through other heat supply steam branch pipelines passes through at least one pressure difference power generation device to become at least one reduced pressure steam, enters at least one low-temperature heat supply network first station heat exchanger, and the temperature of the circulating water is heated from low to high through at least one low-temperature heat supply network first station and high-temperature heat supply network first station heater in sequence to reach the required heating temperature, and the steam becomes condensed water, i.e., steam drainage, which is discharged from the drainage pipe of the corresponding heat supply network first station heat exchanger.

[0005] The high-temperature heat supply network first station heat exchanger is characterized in that the steam source is the heat supply steam branch pipeline, and the high-temperature heat supply network first station heat exchanger is upwardly connected to the heat supply steam main pipe; the steam in the main pipe has been adjusted to a pressure suitable for the high-temperature heat supply network first station heat exchanger before entering the heat supply steam branch pipeline, or a steam pressure difference power generation device is additionally arranged between the heat supply steam branch pipeline and the high-temperature heat supply network first station heat exchanger, and then the reduced pressure steam enters the high-temperature heat supply network first station heat exchanger to heat the circulating water and discharge the drainage.

[0006] The pressure difference power generation device is a steam prime mover or a combination of multiple steam prime movers and other devices, which plays a role in reducing pressure and generating power; one or more pressure difference power generation devices are connected in parallel, series or parallel-serial combination to play a role in reducing pressure and doing work on the steam.

[0007] The low-temperature heat supply network first station heat exchanger uses reduced pressure steam corresponding to the exhaust steam of the pressure difference power generation device, and adopts a single heat exchanger or multiple heat exchangers connected in parallel, series or parallel-serial combination.

[0008] There are more than one pressure difference power generation device and its corresponding low-temperature heat supply network first station heat exchanger as a combination of an application unit along the direction of steam flow, and each application unit is connected in parallel or series; when connected in parallel, the same steam flows into different application units, and when connected in series, the reduced pressure steam discharged from the previous application unit flows into the heat exchanger and the application unit connected in series as the steam source of the pressure difference power generation device of the application unit.

[0009] The pressure difference power generation device, when the exhaust pressure needs negative pressure or smaller positive pressure, installs the vacuumizing device and the interface before and after the corresponding heat network first station pressure reducing steam heat exchanger.

[0010] The flow direction of the circulating water is heated first in the heat exchanger with low steam inlet pressure, and then in the heat exchanger with high steam pressure, or the circulating water is heated by parallel or series-parallel heating and then mixed, so that the water temperature is finally raised to the required temperature, realizing gradient heating of the circulating water and gradient utilization of the steam energy.

[0011] The steam drain of the high-temperature or low-temperature heat network heat exchanger is discharged through the drain pipe, overcooled or not, and then enters the next process separately or as a whole, or flows back to the specified position through the drain backwater pipe.

[0012] Generally, four heat network first stations are provided for each unit, and if the steam flow is 400 t / h, for example, the average steam flow of each of the four heat network first stations is 100 t / h. The "heating steam main pipe" mentioned here refers to a steam main pipe with a flow of 100 t / h, not the large 400 t / h total main pipe. Along the heating steam main pipe, at least two heating steam branch pipelines are connected in parallel and lead to the high-temperature heat network heat exchanger and at least one low-temperature heat network first station heat exchanger. The steam leading to the high-temperature heat network first station heat exchanger passes through the valve and directly enters the high-temperature heat network first station heat exchanger without pressure reduction. This is because, when the heating steam is designed, the relationship between the steam parameters and the maximum temperature of the circulating water heated by the heat network first station heat exchanger should be considered. That is, the steam pressure should match the maximum temperature of the circulating water heated by the heat network first station heat exchanger. When the saturation pressure of the steam is much higher than the maximum temperature of the heat network circulating water, a pressure difference power generation device or other pressure reduction device should be installed at the large total main pipe or a more upstream position. Therefore, after being distributed from the heating steam main pipe, the steam entering the high-temperature heat network first station heat exchanger along the heating steam branch pipeline does not need to be reduced in principle because the high-temperature heat network first station heat exchanger is responsible for heating the circulating water to the maximum heating temperature. That is, the heating steam passes through the heating steam main pipe, the heating steam branch pipeline, and enters the high-temperature heat network first station heat exchanger to heat the circulating water. After the steam releases heat, it becomes saturated or subcooled condensed water, enters the drain backwater pipe, and flows into the next process. However, due to actual working conditions or other reasons, sometimes the heating steam indeed has parameters higher than the demand of the maximum temperature of the heat network circulating water. In this case, a pressure difference power generation device can be considered to be installed before the high-temperature heat network heat exchanger to generate power and reduce the steam pressure, so as to better utilize the steam capacity.

[0013] At least one steam, along with the heating steam main pipe and at least one heating steam branch pipe, enters the low-temperature heat network first station heat exchanger. The task of the low-temperature heat network first station heat exchanger is to raise the temperature of the low-temperature circulating water returned from the heat network, and then enter the high-temperature heat network first station heat exchanger to achieve the required heating temperature of the circulating water. Since the temperature of the heat network circulating water to be heated has a large range, typically 70-130℃, so for example, the high-temperature heat network heater may only need to heat the circulating water from 110℃ to 130℃, while 70-110℃ is completed by other low-temperature heat network heaters. Theoretically, the steam saturation pressure at 110℃ is about 0.14Mpa, and the steam saturation pressure at 130℃ is 0.27Mpa, so a pressure difference power generation device can be installed before the low-temperature heat network heater to generate power after reducing the pressure of the steam. At least 0.13Mpa can be reduced, which is used to generate power, so as to utilize the work function of the steam. Similarly, if the span of 70-110℃ is considered too large, i.e. the gradient is too large, the heating steam can pass through a new pressure difference power generation device through a third heating steam branch pipe, and then enter the second low-temperature heat network first station heat exchanger. For example, the second low-temperature heat network first station heat exchanger raises the temperature of the circulating water by 70-90℃, and then the 90℃ circulating water enters the first low-temperature heat network first station heat exchanger, which heats the circulating water to 110℃, and then enters the high-temperature heat network first station heat exchanger to heat the circulating water from 110℃ to 130℃. Since the highest heating temperature of the second low-temperature heat network first station heat exchanger to the circulating water is 90℃, the corresponding saturation pressure is 0.07Mpa in theory, so theoretically, the 0.27Mpa steam in the main pipe can be reduced by 0.2Mpa (0.27-0.07) for power generation. If the steam of the corresponding pressure difference power generation device of the second low-temperature heat network first station heat exchanger is not sourced from the second heating steam branch pipeline parallel to the heating steam main pipe, but is sourced from the exhaust steam of the pressure difference power generation device after the first heating steam branch pipeline, then the first pressure difference power generation device should consider the steam consumption of the first low-pressure heat network first station heat exchanger and the second low-pressure heat network first station heat exchanger in terms of steam quantity. Correspondingly, the theoretical pressure drop of the steam of the second pressure difference power generation device is 0.14-0.07=0.07Mpa. In this example, three heat network first station heat exchangers are used as a group to heat the circulating water from 70℃ to 130℃, a total temperature rise of 60℃, divided into three stages, each stage of 20℃, from 70-90℃, 90-110℃, and 110-130℃. In actual application, the 60℃ temperature rise can be divided into more stages, with smaller temperature rise in each stage, to facilitate energy gradient utilization, which will not be illustrated one by one here. The condensed water formed after the steam of each heat network first station heat exchanger is discharged will flow back to the system through a separate or parallel drain backwater pipe. During the heating of the circulating water, the circulating water of each group of heat network first stations can flow through the heat exchanger in full flow or in part, and after being heated, return to the circulating water main pipe of each group of heat network heaters to mix and heat the circulating water in the main pipe. Regardless of which way is used, the final heating effect is achieved. Here, no detailed description is given.

[0014] Compared with the prior art, the energy gradient utilization system of the heat network first station heating steam pressure difference power generation cogeneration of the present application has the following beneficial effects: 1. Under the current background of energy-intensive utilization, the circulating water is heated by gradient and the steam energy is utilized by gradient through the system and method, and the heat is generated by cogeneration. The steam power is effectively saved and utilized.

[0015] 2. The additional electric energy generated by the method will effectively reduce the self-consumption of the power plant and the enterprise or reduce the coal consumption of power generation.

[0016] 3. The method effectively reduces the steam pressure and temperature level entering the heat network first station heat exchanger, reduces the investment in system configuration devices such as heat exchangers, valves, and pipelines, and improves the service life. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be further described below in conjunction with the drawings and examples.

[0018] Figure 1 The structure schematic diagram of an embodiment of the present application.

[0019] SUMMARY OF REFERENCE NUMERALS 1, heating steam; 1.1-1.4, reduced pressure steam; 2, heating steam main pipe; 3, valve; 4.0-4.2, heating steam branch pipe; 5.0-5.3, pressure difference power generation device; 6.0, high temperature heat network head station heat exchanger; 6.1-6.3, low temperature heat network head station heat exchanger; 7.0, high temperature heat network head station drain pipe; 7.1-7.3, low temperature heat network head station drain pipe; 7, drain return pipe; 8, vacuum pump; 9.0-9.2, heat network circulating water; 10.0-10.2, circulating water inlet; 11.0-11.2, circulating water outlet; 12.0-12.2, circulating water pipe; 13.0-13.4, steam drain.

[0020] Wherein 9.0, 9.1, 9.2 are heat network circulating water, but the circulating water pipe is arranged in different ways. One of them or similar arrangements can be selected.

[0021] Hereinafter, an embodiment of a heat network head station heating steam pressure difference power generation cogeneration energy gradient utilization system of the present application will be described with reference to the accompanying drawings.

[0022] The embodiments described herein are specific embodiments of the present application, are used to explain the concept of the present application, and are explanatory and exemplary, and should not be interpreted as limiting the embodiments of the present application and the scope of the present application. In addition to the embodiments described herein, those skilled in the art can also employ other technical solutions that are obvious based on the content disclosed in the claims and the specification of the present application, which include any obvious replacement and modification of the embodiments described herein.

[0023] The drawings of the present specification are schematic drawings that assist in explaining the concept of the present application and schematically represent the shape of each part and the relationship between them. Please note that in order to clearly show the structure of each part of the embodiments of the present application, the drawings are not necessarily drawn to the same scale. The same or similar reference numerals are used to represent the same or similar parts.

[0024] A heat network head station heating steam pressure difference power generation cogeneration energy gradient utilization system, comprising: 1, heating steam; 1.1-1.4, reduced pressure steam; 2, heating steam main pipe; 3, valve; 4.0-4.2, heating steam branch pipe; 5.0-5.3, pressure difference power generation device; 6.0, high temperature heat network head station heat exchanger; 6.1-6.3, low temperature heat network head station heat exchanger; 7.0, high temperature heat network head station drain pipe; 7.1-7.3, low temperature heat network head station drain pipe; 7, drain return pipe; 8, vacuum pump; 9.0-9.2, heat network circulating water; 10.0-10.2, circulating water inlet; 11.0-11.2, circulating water outlet; 12.0-12.2, circulating water pipe; 13.0-13.4, steam drain. The 1 heat supply steam from the steam turbine, through 2 heat supply steam main pipe and 3 valve, flows to 6.0 high temperature heat network first station heat exchanger and 6.1 low temperature heat network first station heat exchanger. Along 2 heat supply steam main pipe, at least two 4.0 and 4.1 heat supply steam branch pipelines are connected in parallel, respectively leading to 6.0 high temperature heat network heat exchanger and at least one 6.1 low temperature heat network first station heat exchanger. The steam leading to 6.0 high temperature heat network first station heat exchanger, after passing through 3 valve, directly enters 6.0 high temperature heat network first station heat exchanger without pressure reduction. In principle, it does not need to be matched with pressure reduction, but due to actual working conditions or other reasons, sometimes, 5.0 pressure difference power generation device can be considered to be installed before 6.0 high temperature heat network heater to generate power and reduce the pressure of the steam, and 1.1 reduced pressure steam is discharged, so as to better utilize the work function of the steam. At least one 1 heat supply steam, along 2 heat supply steam main pipe and at least one 4.1 heat supply steam branch pipeline, enters 6.1 low temperature heat network first station heat exchanger. The task of 6.1 low temperature heat network first station heat exchanger is to heat the low temperature circulating water returned from the heat network, and then the low temperature circulating water enters 6.0 high temperature heat network first station heat exchanger to reach the highest heating temperature required by 9.0-9.2 heat network circulating water. Since the heating temperature of 9.0-9.2 heat network circulating water has a large range, 6.0 high temperature heat network heater only needs to heat 9.0-9.2 heat network circulating water from a certain intermediate temperature A to the highest, and from the lowest to the certain intermediate temperature A is responsible for completion by other 6.1 low temperature heat network heater. In theory, the steam pressure required by the certain intermediate temperature A is lower than that required by the highest temperature. Therefore, a 5.0 pressure difference power generation device can be installed before 6.1 low temperature heat network heater to generate power after reducing the pressure of the steam, so as to utilize the work function of the steam. Similarly, if it is considered that the span from the lowest temperature to the certain intermediate temperature A is too large, i.e. the gradient is too large, 1 heat supply steam can be supplied through a new 5.2 pressure difference power generation device through the third 4.2 heat supply steam branch pipeline to enter 6.2 low temperature heat network first station heat exchanger, and the temperature rise of 6.2 low temperature heat network first station heat exchanger for 9.0-9.2 heat network circulating water is a certain temperature B between 10.0-10.2 circulating water inlet temperature and temperature A, and then the circulating water enters 6.1 low temperature heat network first station heat exchanger, and the circulating water is heated by 6.1 low temperature heat network first station heat exchanger from temperature B to temperature A, and then enters 6.0 high temperature heat network first station heat exchanger to be heated to the highest temperature, and flows out from 11.0-11.2 circulating water outlet.

[0025] Since the highest heating temperature of 6.2 low temperature heat network first station heat exchanger for circulating water is temperature B, which is theoretically lower than temperature A, in theory, 1 heat supply steam in 2 heat supply main pipe can be reduced in pressure for work power generation and then reduced in pressure.

[0026] 6.3 Low temperature heat network first station heat exchanger corresponding to 5.3 pressure difference power generation device 1.4 reduced pressure steam is not from parallel to 2 heat supply steam main pipe 4.2 heat supply steam branch pipeline, but from 5.1 pressure difference power generation device exhaust 1.2 reduced pressure steam, then 5.1 pressure difference power generation device should consider the amount of 1.2 reduced pressure steam, parallel 6.1 low pressure heat network first station heat exchanger and 6.3 low pressure heat network first station heat exchanger steam consumption. Corresponding 5.3 pressure difference power generation device steam theoretical pressure drop is 5.1 pressure difference power generation device 1.2 reduced pressure steam pressure minus 5.3 pressure difference power generation device exhaust 1.4 reduced pressure steam pressure.

[0027] In this example, three heat network first station heat exchangers are used as a group. In actual application, temperature rise can be divided into more stages to facilitate energy cascade utilization. Here, it is not described one by one.

[0028] 6.0-6.4 heat network first station heat exchanger steam heat release after the formation of condensate, i.e. 13.1-13.4 steam trap, will be collected in 7 trap return pipe through separate or parallel 7.0-7.3 trap return pipe. In the process of 9.0-9.2 heat network circulating water being heated, for each group of heat network first station circulating water, it can flow through 6.0-6.4 heat network first station heat exchanger in full flow, or part of it can flow through the heat exchanger, and after being heated, it returns to 9.0-9.2 circulating water main pipe of each group of heat network heater, mixes and heats 9.0-9.2 heat network circulating water in 12.0-12.2 circulating water pipe, and flows out from 11.0-11.2 circulating water outlet. No matter which way is used, the final heating effect is achieved. Here, it is not described in detail.

[0029] Further, the heat supply steam can come from the steam extraction of the power plant turbine, other steam boilers, waste heat boilers and other devices that have or can generate steam.

[0030] Further, since the heat network first station usually uses one generator set to heat the circulating water of four (group) heat network first stations, the heat network first station heat exchanger heat supply steam main pipe described in this paper is the main pipe of one group of heat network first stations, not the large main pipe for four heat network first stations to supply steam together, in order to describe clearly.

[0031] Further, the pressure difference power generation device refers to a device that uses the change of steam volume expansion pressure to generate power, and then reduces the steam pressure. To achieve the above functions, it can be a small system itself, or composed of multiple or various devices. It can be a turbine, a screw expander, a steam ejector (thermal pressure machine), etc. and a set of generator and other devices. It can generate power, or can be used to drive other devices to work, etc.

[0032] Further, the pressure difference power generation device can generate power, or can be used to drive other devices.

[0033] Further, after the steam becomes condensed water, i.e. steam drain, a variety of operations such as water tank, drain trap, drain pump, etc. can be used to collect and transport. The condensed water can be subcooled in the first station heat exchanger or connected to the subcooling device, which will not be described here.

[0034] Further, when the exhaust steam of the pressure difference power generation device requires negative pressure, i.e. less than one atmosphere, a vacuum pumping device can be installed in the heat exchanger and the auxiliary system to facilitate the normal operation of the pressure difference power generation device.

[0035] Further, the so-called heat network first station, also known as the heat supply first station, is the heat network first station referred to in this paper. It refers to the indirect heat exchange equipment between the heat supply steam and the primary heat distribution network. The steam can come from a power plant or other steam sources. In addition, the heat supply in power plants, steel plants and chemical plants can also adopt a structure similar to "first station + urban primary heat network" to form a plant first station + plant (primary) heat network. Therefore, these scenarios also apply to "a kind of energy gradient utilization system of heat network first station heat supply steam pressure difference power generation cogeneration".

[0036] The above describes an embodiment of the energy gradient utilization system of heat network first station heat supply steam pressure difference power generation cogeneration. The specific features of the energy gradient utilization system of heat network first station heat supply steam pressure difference power generation cogeneration, such as shape, size and position, can be designed according to the functions of the above disclosed features. These designs are all achievable by those skilled in the art. Moreover, the above disclosed technical features are not limited to the disclosed combinations with other features, and those skilled in the art can also make other combinations between technical features according to the purpose of the present application to achieve the purpose of the present application.

Claims

1. An energy gradient utilization system for combined heat and power (CHP) generation using steam pressure difference from the primary heating station of a heating network, characterized in that it includes: The heat supply steam, the heat supply steam main pipe, the heat supply steam branch pipeline, the pressure difference power generation device, the reduced pressure steam, the high temperature heat network first station heat exchanger, the low temperature heat network first station heat exchanger, the heat network circulating water, and the steam drainage; wherein: the heat supply steam passes through the heat supply steam main pipe, along the heat supply steam branch pipeline, flows to the high temperature heat network first station heat exchanger and at least one low temperature heat network first station heat exchanger; and the heat supply steam from the heat supply steam main pipe along the heat supply steam branch pipeline into the high temperature heat network first station heat exchanger does not pass through the pressure difference power generation device directly into the high temperature heat network first station heat exchanger to heat the circulating water, or passes through the pressure difference power generation device to heat the circulating water; the heat supply steam passing through other heat supply steam branch pipelines passes through at least one pressure difference power generation device to become at least one reduced pressure steam, enters at least one low temperature heat network first station heat exchanger, and the temperature of the circulating water is from low to high, sequentially passes through at least one low temperature heat network first station and high temperature heat network first station heater to heat to reach the required heating temperature, and the steam becomes condensate water, that is, the steam drainage is discharged from the corresponding heat network first station heat exchanger drainage pipe.

2. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, characterized in that: The high temperature heat network first station heat exchanger, the steam source of which is the heat supply steam branch pipeline, the high temperature heat network first station heat exchanger is upwardly connected with the heat supply steam main pipe; the steam in the main pipe has been adjusted to a pressure suitable for the high temperature heat network first station heat exchanger before entering the heat supply steam branch pipe, or a steam pressure difference power generation device is additionally arranged between the heat supply steam branch pipeline and the high temperature heat network first station heat exchanger, and then the reduced pressure steam enters the high temperature heat network first station heater to heat the circulating water and discharge the drainage.

3. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, characterized in that: The pressure difference power generation device is a steam prime mover or a combination of multiple steam prime movers and other devices, which plays a role of reducing pressure and generating power; one or more reduced pressure power generation devices are connected in parallel, series or parallel-serial combination to play a role of working on steam to reduce pressure.

4. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, characterized in that: The low temperature heat network first station heat exchanger uses the reduced pressure steam corresponding to the exhaust steam of the pressure difference power generation device, and adopts a single heat exchanger or multiple heat exchangers connected in parallel, series or parallel-serial combination.

5. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, 2, 3 or 4, characterized in that: In the direction of steam flow, when there is more than one pressure difference power generation device and its corresponding low temperature heat network first station heat exchanger as a combination of an application unit, each application unit is connected in parallel or series, the same steam flows into different application units in parallel, and in series, a part of the reduced pressure steam discharged from the previous steam flow enters the heat exchanger, and the other part flows into the serially connected application unit as the steam source of the reduced pressure power generation device thereof.

6. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, characterized in that: When the exhaust pressure of the pressure difference power generation device needs to be negative pressure or small positive pressure, a vacuum pumping device and an interface are arranged before and after the corresponding heat network first station reduced pressure steam heat exchanger.

7. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 2, characterized in that: The circulating water flows from the steam inlet of the heat exchanger with low pressure first, and then flows to the heat exchanger with high pressure for heating, or the circulating water is heated by the parallel or series-parallel heating of the main circulating water, and finally the water temperature is raised to the required temperature, realizing the gradient heating of the circulating water and the gradient utilization of the steam energy.

8. The energy gradient utilization system of heat supply and power cogeneration by pressure difference of heat supply steam in the first station of heat supply network according to claim 1, 2, 3 or 4, characterized in that: The steam drainage of the high temperature or low temperature heat network heat exchanger is discharged through the drainage pipe, and is supercooled or not, and is respectively or integrally input into the next process, or flows back to the specified position through the drainage return pipe.

Images