CN115406131B - Water-heat cogeneration system based on ejector and operation method - Google Patents

Abstract

The invention provides an ejector-based water, heat and power cogeneration system and an operating method, which belong to the technical field of water, heat and power cogeneration. The ejector-based water, heat and power cogeneration system includes: a first thermal compressor, a second thermal compressor machine, a preheater group, an evaporator group, a condenser, a first heater, and a second heater; the evaporator group includes multiple evaporators that are connected in sequence; the preheater group includes multiple preheaters that are connected in sequence; The condensed water outlet of each effect evaporator in the evaporator group is connected to the fresh water outlet pipe. The ejector-based water, heat and power cogeneration system provided by the present invention adopts a multi-effect processing method. The first thermal compressor and the second thermal compressor are connected in series. The first thermal compressor injects the outlet steam of the second thermal compressor, which improves efficiency. The injection ratio further utilizes the steam waste heat of the final effect evaporator. At the same time, the preheater group is used to make full use of the low-grade waste heat in the heating process and save the consumption of high-grade steam.

Description

An ejector-based water, heat and power cogeneration system and operation method

Technical field

The invention relates to the technical field of water, heat and power cogeneration, and in particular to an ejector-based water, heat and power cogeneration system and an operating method.

Background technique

Combined heat and power (also known as steam and electricity symbiosis, English: Cogeneration, combined heat and power, abbreviation: CHP) uses a heat engine or power station to produce electricity and useful heat at the same time. Trigeneration or combined cooling, heat and power (CCHP) refers to the simultaneous generation of electricity and useful heat and cooling from fuel combustion or solar collectors.

Cogeneration is a process that produces electricity and heat energy at the same time. Compared with heat and power division, it can significantly improve fuel utilization, has good economic and social benefits, and is an important technical means to achieve a circular economy. Thermal power unit combined heating system and low-temperature multi-effect distillation seawater desalination technology have become a new method of water, heat and power cogeneration. Large thermal power units have the problem of a large amount of waste heat being wasted during seawater desalination and heating. How to optimize the system configuration? Therefore, improving the energy utilization efficiency of water, heat and electricity trigeneration is an urgent problem to be solved.

The single-stage steam ejector uses the steam extracted from the power plant as its motive steam to inject certain-effect secondary steam of the low-temperature multi-effect distillation seawater desalination system, and the outlet steam is used as the first-effect heating steam of the desalination system. Single-stage steam ejector can also be used for heating or industrial steam; although single-stage steam ejector can achieve steam parameter matching between thermal power units and desalination systems, it cannot achieve better cascade utilization of energy. In industrial steam systems, many temperature reducing and pressure reducing valves are used, which wastes a lot of steam. In addition, the flexibility of water, heat and power cogeneration is not high enough. When the thermal power unit is running at low load, the steam injector is changing. The performance deteriorates under working conditions, resulting in a reduction in the ejection coefficient and ejection capability, which directly affects the operation of the water-thermal-electric coupling system.

Contents of the invention

Therefore, the present invention provides an ejector-based water heat and power cogeneration system and an operating method.

In order to solve the above technical problems, the present invention provides an ejector-based water heat and power cogeneration system, including:

A first thermal compressor, a second thermal compressor, a preheater group, an evaporator group, a condenser, a first heater, and a second heater;

The evaporator group includes a plurality of evaporators connected in sequence, with a first-effect evaporator and a final-effect evaporator at the beginning and end respectively;

The preheater group includes a plurality of preheaters connected in sequence, with the first and last preheaters being the No. 1 preheater and the last preheater respectively;

The steam inlet of the first-effect evaporator is connected to the first thermal compressor, and the condensed water outlet of each effect evaporator in the evaporator group is connected to the fresh water outlet pipe;

The secondary steam outlet of the final effect evaporator is connected to the condenser and the second thermal compressor respectively, and the steam outlet of the second thermal compressor is connected to the injection steam inlet of the first thermal compressor;

The seawater inlet of the condenser is connected to the feed seawater pipeline, and the seawater outlet of the condenser is connected to the seawater inlet of the last preheater;

Among them, the seawater outlet from the second preheater to the last preheater is divided into two paths, one is connected to the previous preheater, and the other corresponds to the seawater inlet connecting the second effect evaporator to the last effect evaporator.

Optionally, the first heater is connected to the return water of the heating network, and the steam outlet of the second thermal compressor is connected to the steam inlet of the first heater;

The hot water outlet of the first heater is connected to the hot water inlet of the second heater, and the drain port of the second heater is connected to the hot end inlet of the No. 1 preheater.

Optionally, the number of evaporators in the evaporator group is greater than or equal to 4.

Optionally, the number of preheaters in the preheater group is greater than or equal to 4.

Methods of operation are also provided, including the ejector-based water cogeneration system described above, further comprising the following steps:

The seawater is preheated in the preheater group and then enters the evaporator group respectively. The steam from the first thermal compressor enters the first-effect evaporator and condenses and releases heat. The seawater is heated, the temperature rises, and then partially vaporizes, generating a certain mass flow rate. The secondary steam of the first-effect evaporator condenses and releases heat in the second-effect evaporator, heats the material seawater flowing into it, and generates steam for the next-effect evaporator, until the final-effect evaporator, and the evaporator group The condensed steam after internal heat exchange enters the fresh water outlet pipe;

The second thermal compressor uses the driving steam to inject, and the outlet steam of the second thermal compressor is injected by the first thermal compressor using the driving steam, and then enters the first-effect evaporator after mixing.

Optionally, it also includes the step of sequentially entering the return water from the heating network into the first heater and the second heater to absorb heat and then provide external heating.

Optionally, the water drained from the first heater and the hot end outlet water of the last preheater are refined and then flowed into the condenser of the steam turbine unit.

Optionally, the hot water network absorbs heat in the first heater and the second heater respectively through pipelines and then provides external heating.

Optionally, the raw seawater is divided into two parts after being preheated in the condenser, one part is discharged back to the environment, and the other part enters each effect evaporator as raw seawater.

Optionally, the heat source of the first heater is the mixed steam after the second thermal compressor uses the driving steam to inject the secondary steam of the final effect evaporator.

The technical solution of the present invention has the following advantages:

1. The ejector-based water, heat and power cogeneration system provided by the present invention adopts a multi-effect processing method. The first thermal compressor and the second thermal compressor are connected in series. The first thermal compressor injects the outlet steam of the second thermal compressor. The injection ratio is increased and the steam waste heat of the final effect evaporator is further utilized. At the same time, the preheater group is used to make full use of the low-grade waste heat in the heating process and save the consumption of high-grade steam.

2. The ejector-based water, heat and power cogeneration system provided by the present invention makes full use of the low-grade waste heat in the seawater desalination process to replace part of the high-grade steam, thereby reducing heating costs.

Description of the drawings

In order to more clearly explain the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings that need to be used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description The drawings illustrate some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a schematic structural diagram of an ejector-based water heat and power cogeneration system provided by an embodiment of the present invention.

Explanation of reference symbols:

1. The first thermal compressor; 21. First effect evaporator; 22. Second effect evaporator; 23. Third effect evaporator; 24. Final effect evaporator; 3. Condenser; 41. No. 1 preheater; 42 , No. 2 preheater; 43. No. 1 preheater; 5. Concentrated seawater outlet pipe; 6. Fresh water outlet pipe; 7. Second thermal compressor; 8. First heater; 10. Second heater; 11. Feed seawater pipeline.

Detailed ways

The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limitations of the invention. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Example 1

This embodiment provides a specific implementation of an ejector-based water heat and power cogeneration system, as shown in Figure 1, including a first thermal compressor 1, a second thermal compressor 7, a preheater group, and an evaporator. Group, condenser 3, first heater 8, second heater 10. The evaporator group includes a plurality of sequentially connected evaporators, with the first-effect evaporator 21 and the last-effect evaporator 24 at the beginning and end respectively; the preheater group includes a plurality of preheaters connected in sequence, with the first-effect evaporator 41 at the beginning and end respectively. and the last preheater 43; the steam inlet of the first effect evaporator 21 is connected to the first thermal compressor 1, and the condensed water outlet of each effect evaporator in the evaporator group is connected to the fresh water outlet pipe 6; the last effect evaporator 24 The secondary steam outlet of the second thermal compressor 7 is connected to the condenser 3 and the second thermal compressor 7 respectively. The steam outlet of the second thermal compressor 7 is connected to the injection steam inlet of the first thermal compressor 1; the seawater inlet of the condenser 3 is connected to the inlet. The feed seawater pipe 11 is connected, and the seawater outlet of the condenser 3 is connected with the seawater inlet of the last preheater 43; among them, the seawater outlet of the second preheater 42 to the last preheater 43 is divided into two roads, one road is connected to the seawater inlet of the last preheater 43. The No. 1 preheater is connected, and the other path corresponds to the seawater inlet connecting the second-effect evaporator 22 to the final-effect evaporator 24 respectively.

Specifically, the first heater 8 is connected with the return water of the heating network, the steam outlet of the second thermal compressor 7 is connected with the steam inlet of the first heater, and the hot water outlet of the first heater 8 is connected with the second heater 10 The water inlet of the network is connected, and the drain port of the second heater 10 is connected with the hot end inlet of the No. 1 preheater 41 .

Specifically, the number of evaporators in the evaporator group is not less than 4; the number of preheaters in the preheater group is not less than 4. Among them, the number of evaporators is set corresponding to the number of preheaters. As shown in Figure 1, they are the first effect evaporator 21, the second effect evaporator 22, the third effect evaporator 23... the final effect evaporator 24, the No. 1 preheater 41, the No. 2 preheater 42... the last preheater 43, the reference numbers are only for illustration and do not refer to the number and order of evaporators and preheaters. Among them, the seawater outlet of condenser 3 is connected to the seawater inlet of the last preheater 43. The seawater outlet of the last preheater 43 is divided into two channels. One channel flows into the previous preheater, and the other channel flows to the final effect evaporator. Within 24. The seawater outlet of the No. 1 preheater 41 is connected with the seawater inlet of the first-effect evaporator 21 . The seawater outlet of the No. 2 preheater 42 is divided into two channels, one channel flows into the No. 1 preheater 41, and the other channel flows into the second effect evaporator 22.

The steam from the extraction port of the steam turbine unit passes through the second heater 10 to heat the return water of the heating network, and then enters the preheater group to heat the sea water. Specifically, the second heater 10 is a peak heater.

The first thermal compressor 1 and the second thermal compressor 7 are connected in series, and the steam inlet of the first thermal compressor 1 is connected with the steam outlet of the second thermal compressor 7 .

Specifically, each effect evaporator in the evaporator group is connected to a concentrated seawater outlet pipe 5, and is finally discharged from the concentrated seawater outlet pipe 5 of the final effect evaporator 24.

Example 2

This embodiment provides a specific implementation of the operation method, which is implemented using the ejector-based water cogeneration system in Embodiment 1, including the following steps: seawater is sequentially preheated in the preheater group and then evaporated respectively. The steam from the first thermal compressor 1 enters the first-effect evaporator 21 and condenses and releases heat. The seawater is heated, the temperature rises, and then partially vaporizes to generate secondary steam with a certain mass flow. The second-effect evaporator 21 The secondary steam condenses and releases heat in the second-effect evaporator 22, heating the material seawater flowing into it, and generating steam for the next-effect evaporator until the final-effect evaporator 24. The cooled steam enters after heat exchange in the evaporator group. Fresh water outlet pipe 6; the second thermal compressor 7 uses driving steam to inject, and the outlet steam of the second thermal compressor 7 is injected by the first thermal compressor 1 using the driving steam, and then enters the first-effect evaporator 21 after mixing. It also includes the step of sequentially entering the return water from the heating network into the first heater 8 and the second heater 10 to absorb heat and then provide external heating.

Among them, in the evaporator group, since the pressure of the last effect evaporator is lower than the pressure of the previous effect evaporator, the remaining unevaporated seawater in the previous effect evaporator 21 flows in step by step without the need for a raw material pump. In the next effect evaporator, the concentrated seawater from the previous effect can flash evaporate in the latter effect evaporator. This process is repeated until the final effect evaporator 24; the secondary steam of the final effect evaporator 24 One part leads to the condenser 3, and the feed seawater is initially heated through the condenser 3. A part is ejected by the second thermal compressor 7 using driving steam, and the outlet steam of the second thermal compressor 7 is driven by the first thermal compressor 1. The steam is injected, mixed and then enters the first-effect evaporator 21 as a heat source.

The water drained from the first heater 8 and the hot end outlet water of the last preheater 43 is refined and then flows into the condenser of the steam turbine unit.

The raw seawater is divided into two parts after being preheated in the condenser 3, one part is discharged back to the environment, and the other part enters each effect evaporator as raw seawater.

The heat source of the first heater 8 is the mixed steam after the second thermal compressor 7 uses the driving steam to inject the secondary steam of the final effect evaporator 24 .

The return water from the heating network enters the first heater 8 and the second heater 10 in turn to absorb heat and provide external heating; the heat source steam of the first heater 8 is used by the second thermal compressor 7 to drive the steam to the final evaporator. The mixed steam after the secondary steam of 24; the heat source end steam of the second heater 10 is the steam extraction port in the steam turbine unit that matches the steam parameter requirements.

Obviously, the above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. An exhaustive list of all implementations is neither necessary nor possible. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims (9)

1. An ejector-based water heat and power cogeneration system, characterized by including: The first thermal compressor (1), the second thermal compressor (7), the preheater group, the evaporator group, the condenser (3), the first heater (8), and the second heater (10); The evaporator group includes a plurality of evaporators connected in sequence, with a first-effect evaporator (21) and a final-effect evaporator (24) at the beginning and end respectively; The preheater group includes a plurality of preheaters connected in sequence, with the first and last preheaters (41) and the last preheater (43) respectively; The steam inlet of the first effect evaporator (21) is connected to the first thermal compressor (1), and the condensed water outlet of each effect evaporator in the evaporator group is connected to the fresh water outlet pipe (6); The secondary steam outlet of the final effect evaporator (24) is connected to the condenser (3) and the second thermal compressor (7) respectively, and the steam outlet of the second thermal compressor (7) is connected to the first thermal compressor. The injection steam inlet of the thermal compressor (1) is connected; The seawater inlet of the condenser (3) is connected to the feed seawater pipe (11), and the seawater outlet of the condenser (3) is connected to the seawater inlet of the last preheater (43); Among them, the seawater outlet from the No. 2 preheater (42) to the last preheater (43) is divided into two channels, one channel is connected to the previous No. 1 preheater, and the other channel is connected to the second-effect evaporator (22) to Seawater inlet of the final effect evaporator (24); The first heater is connected to the return water of the heating network, and the steam outlet of the second thermal compressor (7) is connected to the steam inlet of the first heater; The hot network water outlet of the first heater is connected to the hot network water inlet of the second heater (10), and the drain port of the second heater (10) is connected to the hot end inlet of the No. 1 preheater (41). Connected. 2. The ejector-based water cogeneration system according to claim 1, wherein the number of evaporators is greater than or equal to 4. 3. The ejector-based water cogeneration system according to claim 1, characterized in that the number of the preheaters is greater than or equal to 4. 4. The operating method includes the ejector-based water heat and power cogeneration system according to any one of claims 1 to 3, characterized in that it also includes the following steps: The seawater is preheated in the preheater group in turn and then enters the evaporator group respectively. The steam from the first thermal compressor (1) enters the first-effect evaporator (21) and condenses and releases heat. The seawater is heated and the temperature rises, thereby partially Vaporization produces secondary steam with a certain mass flow. The secondary steam of the first-effect evaporator (21) condenses and releases heat in the second-effect evaporator (22), heats the material seawater flowing into it, and generates water for use in the next-effect evaporator. The steam reaches the final effect evaporator (24), and the condensed steam after heat exchange in the evaporator group enters the fresh water outlet pipe (6); The second thermal compressor (7) uses driving steam to inject, and the outlet steam of the second thermal compressor (7) is injected by the first thermal compressor (1) using the driving steam, and then enters the first-effect evaporator (21) after mixing. . 5. The operation method according to claim 4, further comprising the step of sequentially entering the return water from the heating network into the first heater (8) and the second heater (10) to absorb heat and provide external heating. 6. The operation method according to claim 4, characterized in that the first heater hydrophobic and hot end outlet water of the last preheater (43) are refined and then flowed into the condenser of the steam turbine unit. 7. The operation method according to claim 4, characterized in that the hot network water absorbs heat in the first heater (8) and the second heater (10) respectively through the pipeline and then supplies heat to the outside. 8. The operation method according to claim 4, characterized in that the raw seawater is divided into two parts after being preheated in the condenser (3), one part is discharged back to the environment, and the other part enters each effect evaporator as raw seawater. . 9. The operating method according to claim 8, characterized in that the heat source of the first heater (8) is the second thermal compressor (7) using the driving steam to inject the two ends of the final effect evaporator (24). Mixed steam after secondary steam.