WO2019042020A1

WO2019042020A1 - Heat recovery device

Info

Publication number: WO2019042020A1
Application number: PCT/CN2018/095071
Authority: WO
Inventors: 冯煜珵
Original assignee: 冯煜珵
Priority date: 2017-08-31
Filing date: 2018-07-10
Publication date: 2019-03-07
Also published as: CN107388231A

Abstract

A heat recovery device, which comprises a primary steam pipe (2), an ancillary pipe (01), a water-feeding heater, and a steam-side regulation valve (02) that is provided on the ancillary pipe (01), wherein the steam-side regulation valve (02) is configured to regulate the primary steam in the ancillary pipe (01) so as to control the steam extraction pressure behind the stream-side regulation valve (02) so that the exit temperature of the water-feeding heater is controlled, thereby reaching a pre-set water-feeding temperature.

Description

Heat recovery equipment

The present application claims the priority of the Chinese Patent Application, filed Jan.

Technical field

The present disclosure relates to the field of thermal power generation, for example, to a regenerative device.

Background technique

China's electric power is mainly regulated by thermal power generating units, and the low-load operation of thermal power generating units has become the norm. With the official release of China's "Eleventh Five-Year Plan for Electric Power Development (2016-2020)", "adding emphasis on peak capacity building and improving system flexibility" has become one of the important tasks of thermal power generating units, which means firepower. The deep peak shaving and system flexibility of the generator set put forward higher requirements. Even the concept of “ultra-low-load operation” has been put forward in the industry. In fact, the thermal power generating unit operates at low load and is environmentally friendly and safe. Economic and other difficulties, including Selective Catalytic Reduction (SCR) denitration devices need to exit operational problems, boiler hydrodynamic instability, boiler combustion instability and low cycle efficiency issues.

Chinese patent ZL201110459533.2 discloses an adjustable feed water regenerative device, that is, compared with the conventional steam turbine generator set, the final stage extraction pressure set on the high pressure cylinder is higher than the conventional maximum extraction pressure of the high pressure cylinder; An extraction steam regulating valve is disposed on the final stage steam extraction pipe, and then the feed water is heated back and forth through the feed water heater. During the operation, the final stage extraction can be adjusted through the valve, so that the pressure after the extraction control valve is basically unchanged when the unit is under variable load, and the temperature of the boiler feed water is maintained substantially unchanged by the final stage feed water heater. .

However, the system and method provided by the patent still have shortcomings. Due to the sliding pressure operation of the unit, the pressure of the extraction port is also low when the unit is in the ultra-low load and the starting stage, and the denitration in the start-up phase or the ultra-low-load phase is still not achieved. In addition, for subcritical units, due to the low pressure parameters of the subcritical units, there is also the problem that the denitration does not meet the requirements and exits during the low load phase; more importantly, the system and method provided by the patent It also has application limitations, and it cannot be directly applied to units with no additional extraction ports for steam turbines.

On the other hand, modern thermal power generators are equipped with a bypass system to meet the requirements of start-stop and accident conditions of the unit. When the unit starts, a large amount of steam generated by burning coal and fuel is passed through the boiler. The road system is finally fed into the condenser until the steam turbine has passed the steam quality and the steam parameters meet the rushing conditions. The steam turbine is started to rush, and finally the grid is connected to the grid, and the bypass is finally closed. The cold start of the traditional thermal power generating unit is about 8-10 hours from ignition to grid connection. During this period, a large amount of steam is sent to the condenser through the bypass system, and the heat is lost although the working medium is recovered. In addition, there are problems such as low temperature condensation, ash blocking and corrosion in equipment such as low pulverized coal burning rate, fuel black smoke and tail flue air preheater in the start-up phase.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

In view of this, the present disclosure provides a method of regenerative equipment, which can solve the problems faced by the above-mentioned low load, start-up phase and the deficiencies of the adjustable feedwater regenerative equipment in the related art.

The application provides a regenerative device, including:

Main steam pipe

High pressure cylinder

a final feedwater heater that uses the main steam in the main steam line as a heat source;

The final stage extraction pipe connects the high pressure cylinder and the final stage feed water heater;

An additional pipe added to the main steam pipe, the additional pipe being connected to the feed water heater;

a steam side regulating valve disposed on the additional pipe, configured to adjust main steam in the additional pipe to control an extraction pressure after the steam side regulating valve to control an outlet temperature of the feedwater heater To reach the preset feed water temperature.

In an embodiment, further comprising an isolation valve respectively disposed on the final stage extraction conduit and the additional conduit;

In an embodiment, further comprising an additional adjustable final stage feedwater heater, the additional adjustable final stage feedwater heater being disposed at a rear of the final feedwater heater according to a water flow direction; the additional conduit connection The main steam line and the additional adjustable final stage feed water heater.

In an embodiment, at least one water side regulating valve is further included, the water side regulating valve being connected in parallel with the additional adjustable rear final stage feedwater heater.

The regenerative equipment of this embodiment does not need to provide an additional steam turbine extraction port, including the subcritical unit. In the normal load operation phase of the unit, the main steam can still have the main steam pressure and the super low load pressure of the unit. Sufficient pressure to meet the requirements of increasing the feed water temperature to meet the denitration operation.

The regenerative device of the embodiment can be put into use in the startup phase of the unit, and a part of the heat of a large amount of steam originally sent to the condenser through the bypass system can be recovered, used for supplemental heating boiler feed water in the startup phase, and the feed water temperature is increased. Indirect replenishment preheats the entire boiler, which can significantly reduce the fuel and coal consumption during the start-up phase. Since the regenerative equipment can be put into operation during the start-up phase, equipment such as an empty preheater with low pulverized coal combustion rate, black smoke and tail flue is prone to low temperature condensation, ashing and corrosion. Such problems can be ensured that the unit can be put into the SCR denitration unit before the grid connection, and the life of the SCR catalyst can be extended.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a schematic structural view of a regenerative device provided in Embodiment 1.

2 is a schematic structural view of a heat recovery device provided in Embodiment 2.

3 is a schematic structural view of a regenerative device provided in Embodiment 3.

Among them: 1 - final stage extraction port; 10 - final stage extraction pipe; 11 - final stage feed water heater; 2 - main steam line; 3 - other devices; 4 - high pressure cylinder; 5 - final feed water; 6 - water Side regulating valve; 01-additional pipe; 02-steam side regulating valve; 03-additional adjustable rear final stage feedwater heater; 04, 04'-insulation valve.

Detailed ways

Example 1

1 is a schematic structural view of a regenerative apparatus provided in Embodiment 1, which is provided on the basis of a final stage extraction port 1, a final stage extraction steam 10, a final stage feed water heater 11, and a main steam line 2. An additional pipe 01, a steam side regulating valve 02 on the additional pipe, and an additional adjustable final stage feed water heater 03 are provided.

The additional adjustable rear final stage feed water heater 03 is connected to the main steam line 2 via an additional line 01, which is arranged on the additional line 01. The steam side regulating valve 02 is for regulating the main steam in the additional pipe 01, and controls the feed water temperature of the outlet of the additional adjustable rear final stage feed water heater 03 by controlling the pressure after the steam side regulating valve 02.

The control method of the present embodiment will be described in detail by taking an example of a 1000 MW unit of a power plant, wherein the steam turbine is an ultra-supercritical single-shaft, one-time reheat or four-cylinder four-row steam condensing steam turbine.

For example, the main steam parameter at rated operating conditions (1000 WM) is 27 MPa/600 °C. During the operation phase of the unit, as the unit load decreases, the pressure of the feed water heater is controlled to be about 8.5 MPa by adjusting the steam side regulating valve to maintain the feed water temperature at about 300 °C.

During the start-up phase of the unit, the steam generated by the consumption of coal and fuel can be replenished by the additional pipe 01 into the additional adjustable rear final stage feed water heater 03 to increase the feed water temperature during the start-up phase, reducing the feed water temperature during the start-up phase. The inlet of the water wall in the start-up phase is low, which solves the problem of hydrodynamic instability during the start-up phase, which creates favorable conditions for the quick start of the unit, achieves a significant reduction in the starting energy consumption, and solves the pulverized coal combustion generated in the traditional start-up phase. Equipment such as low enthalpy rate, black smoke from fuel, and air preheaters in the tail flue are prone to low temperature condensation, ashing and corrosion, and can ensure that the unit can be put into the SCR denitration unit before being connected to the grid. SCR catalyst life.

Example 2

2 is a schematic structural view of a regenerative apparatus provided in Embodiment 2. This embodiment is provided on the basis of the final stage extraction port 1, the final stage extraction steam 10, the final stage feed water heater 11, and the main steam line 2. An additional pipe 01, a steam side regulating valve 02 on the additional pipe, an additional adjustable rear final stage feed water heater 03, and a water side regulating valve 6 are provided.

The difference between this embodiment and the embodiment 1 is that a water side regulating valve 6 is added, which is connected in parallel with the additional adjustable rear final stage feed water heater 03. Therefore, the additional adjustable rear final stage feed water heater 03 can be designed as a partial capacity. The feed water heater reduces the cost of the heater.

The method of using the regenerative apparatus of the present embodiment differs from that of the first embodiment in that the feed water temperature is the feed water temperature after the additional adjustable rear stage feed water heater 03 outlet and the water side regulating valve 6 outlet are mixed. The rest are consistent and will not be described here.

Example 3

3 is a schematic structural view of a regenerative apparatus provided in Embodiment 3. In this embodiment, the isolation valve 04' and the final stage water supply are provided at the final stage extraction port 1, the final stage extraction steam 10, and the final stage extraction stage 10. On the basis of the heater 11 and the main steam pipe 2, an additional pipe 01, a steam side regulating valve 02 on the additional pipe, and an isolation valve 04 are added.

The difference between this embodiment and the first embodiment is that there is no additional adjustable rear final stage feed water heater 03, and an additional isolation valve 04 is added to the additional pipeline to facilitate the high load operation of the unit, such as when the heat recovery device is not required. The isolation valve 04 can be used to close, and when the unit load is low to a preset level or when the unit is started, the final feed water temperature cannot meet the requirements of the denitration device operation. At this time, the isolation valve 04 can be switched to the present. The heat recovery device, at the same time, closes the isolation valve 04' on the final stage extraction steam, and uses the main steam to throttle through the regulating valve 02. Since the main steam pressure itself is high, sufficient feed water temperature can be ensured. The rest of the method for using the regenerative device of this embodiment is the same as that of Embodiment 1, and details are not described herein again.

The embodiments of the present application have been described in detail above. The regenerative device of the present application may have various combinations according to whether the water side regulating valve is disposed on the water side, whether the additional adjustable rear final stage feed water heater is provided, and the adjustable adjustable rear final stage feed water heater has different capacities.

Claims

A regenerative device comprising:

Main steam pipe

High pressure cylinder

a final stage feed water heater, wherein the final stage feed water heater is configured to use main steam in the main steam line as a heat source;

The final stage extraction pipe is arranged to connect the high pressure cylinder and the final stage feed water heater;

An additional conduit disposed on the main steam conduit and configured to connect the additional conduit to the feedwater heater;

a steam side regulating valve disposed on the additional pipe, configured to adjust main steam in the additional pipe to control an extraction pressure after the steam side regulating valve to control an outlet temperature of the feedwater heater To reach the preset feed water temperature.
The regenerative apparatus according to claim 1, further comprising an isolation valve provided on said last stage extraction duct and said additional duct, respectively.
A regenerative apparatus according to claim 2, further comprising an additional adjustable rear final stage feed water heater, said additional adjustable rear final stage feed water heater being disposed at a rear portion of said last stage feed water heater according to a water flow direction; An additional conduit is provided to connect the main steam conduit and the additional adjustable final stage feedwater heater.
The regenerative apparatus according to claim 3, further comprising at least one water side regulating valve disposed to be connected in parallel with said additional adjustable rear final stage feed water heater.