KR20000021783A - Device for unifying flow of heat recovery steam generator - Google Patents

Abstract

PURPOSE: A flow unifying device is provided to prevent local overheating of the front end of a fin and a wall of a heat conduction tube of a high pressure super-heater or a reheater. CONSTITUTION: A flow unifying device applying a heat recovery steam generator composed of a high pressure and low pressure super-heater connected to the outlet of a gas turbine, receiving the delivery of heat from exhaust gas and emitting the steam supplied to a steam turbine, a high pressure and lower pressure evaporator, and an economizer is additionally composed of a perforated plate(12) installed on the outlet of the gas turbine and an exhaust gas flow path(2) which is a connected path of a steam generator(1), a honeycomb and a screen grid(13). Herein, the perforated plate, the honeycomb and the screen grid are installed to be vertical to the flow direction of the exhaust gas to form uniform flow in the process of which the exhaust gas passes the perforated plate and the screen grid.

Description

Flow Homogenizer of Heat Recovery Steam Generator

The present invention relates to a flow homogenizer that can be installed in a combined heat recovery steam generator (HRSG) or an exhaust gas boiler, wherein the flow homogenizer is an inlet gas inlet of the heat recovery steam generator. Attached to the inlet, the exhaust gas at the outlet of the gas turbine passes through to eliminate the non-uniformity of temperature and flow rate and to convert into a uniform flow form, which flows into the heat recovery steam generator, thereby improving the efficiency of the heat recovery steam generator and The present invention relates to a device capable of preventing damage to a heat transfer tube of a superheater.

In general, a combined power generation system burns fuel to generate high-pressure, high-temperature combustion gas, and uses the high-temperature, high-pressure combustion gas to drive a gas turbine to generate electricity, and a gas to drive and discharge the gas turbine. It consists of a heat recovery steam generator for recovering heat and a steam turbine system for generating electricity by driving a steam turbine using high temperature and high pressure steam generated from the heat recovery steam generator.

1 is a side cross-sectional view schematically illustrating a structure of a conventional heat recovery steam generator, wherein the heat recovery steam generator or the heat recovery boiler, which is used for combined power generation, is connected to an outlet of a gas turbine to discharge exhaust gas discharged at a high temperature. Used for the purpose of recovering heat while bypassing, it consists of an evaporator that makes saturated liquid into saturated steam, a superheater that heats saturated steam to a high temperature, and a pelletizer that heats the water supplied from the condenser with saturated liquid. The unit is designed to heat up to the temperature conditions required by the steam turbine in the design.

However, when gas turbine exhaust gas (Gas Turbine Exhaust, GTE) is introduced into the array gas steam generator, it is completely turbulent (turbulent flow), it is in a very uneven state in terms of speed and temperature.

With respect to the inlet section of the HRSG, the gas velocity changes by ± 400% and thus the gas temperature by ± 55 ° C.

As shown in FIG. 1, the conventional heat recovery steam generator has an exhaust gas having a non-uniform temperature and a flow rate at a gas turbine outlet as it is introduced into the heat recovery steam generator 1 ′.

Figure 2 is a simulation graph showing the flow non-uniformity of the gas turbine exhaust gas through the numerical analysis it can be seen that the flow is very non-uniform in the inlet duct flue gas passage (2 ').

In addition, FIG. 3 is an example of dividing the velocity distribution layer obtained by the gas turbine outlet flue gas velocity distribution experiment in the AA line of FIG. 2 by the density of diagonal lines. In some regions, the velocity vector may be vertical. In other regions, the flow pattern is uneven enough to exist in a direction opposite to the main flow direction.

Such fluctuations in flue gas temperature and flow pattern are caused by changes in atmospheric temperature, changes in gas turbine load, and injection of steam or water to reduce emissions of the gas turbine.

Therefore, due to the change in the gas turbine outlet exhaust gas (GTE), as shown in FIG. 1, the heat absorption amount of each heat exchanger tube of the evaporator 4 is changed, and the amount of steam generation is often changed. The fin tip temperature or tube wall temperature of the three heat transfer tubes, either high pressure superheater or reheater, which is one of the components of the stage, becomes too high locally. However, fatal troubles that cause the tube wall to break often occur.

Therefore, there is a problem that a tricky circulation system design must be added to supply appropriate water to each heat pipe of the evaporator so that the array gas steam generator operates safely within the critical range.

The present invention devised to solve the above problems is composed of a device for equalizing the flow state of the exhaust gas flowing into the array gas steam generator from the gas turbine, so that the fin tip temperature or the heat transfer pipe wall of the high-pressure superheater or reheater heat transfer pipe is Local heat is prevented from excessive heating, and the heat absorption of each heat pipe of the evaporator and the amount of steam generated according to it are constant and even to extend the life of the heat recovery steam generator and to design the circulation system of the evaporator in consideration of the uneven flow of exhaust gas. The purpose is to provide a fluid homogenizer that does not have to be complicated and has an effect of increasing thermal efficiency.

The object of the present invention is the exhaust gas flow path, which is installed at the outlet of the gas turbine and the exhaust gas flow path on the duct of the array gas steam generator, and comprises a perforated plate, honeycomb, and a screen grid. It can be solved by the flow homogenizer, it will be described in detail with reference to the accompanying drawings.

1 is a side cross-sectional view schematically illustrating the structure of a conventional heat recovery steam generator.

Figure 2 shows numerically the flow nonuniformity of the gas turbine exhaust gas

Simulation graph.

3 is an irregular front face of a gas turbine outlet flue gas at line A-A of FIG.

Graph showing velocity distribution layer.

Figure 4 is a side cross-sectional view of the array recovery steam generator to which the flow homogenization apparatus of the present invention is applied.

* Description of the symbols for the main parts of the drawings *

1. Heat recovery steam generator 2. Flue gas flow path

3. High pressure superheater 4. High pressure evaporator

11. Flow Homogenizer 12. Perforated Plate

13. Screen grid

Figure 4 shows a side cross-sectional view of the array recovery steam generator to which the flow homogenizing device 11 of the present invention is applied.

The present invention is connected to the outlet of the gas turbine in a high-pressure and low-pressure superheater for receiving the heat transfer from the incoming exhaust gas to discharge the steam supplied to the steam turbine, a high-pressure and low-pressure evaporator, an array gas steam generator consisting of a coal mill It consists of a perforated plate 12 or a honeycomb and a screen grid 13, which are installed in the exhaust gas flow passage 2, which is a connection passage between the outlet of the gas turbine and the array gas steam generator (1).

Hereinafter, the operation of the present invention will be described.

According to the present invention, by attaching the flow homogenizer 11 to the heat recovery steam generator 1 or the exhaust gas boiler, the flow pattern of the exhaust gas at the inlet side of the heat recovery steam generator is uniform, thereby eliminating the possibility of breakage of the heat transfer pipe and the evaporator. This is to solve the complexity of the circulatory system design, as shown in FIG.

The flow homogenizing device 11 of the present invention is installed at the front end of the High Pressure Superheater or Reheater 3, which is the exhaust gas inlet side of the heat recovery steam generator.

The gas turbine outlet flue gas (GTE) is discharged under a very uneven flow due to gas turbine load fluctuations, and the duct width is rapidly expanded as shown in the drawing. Due to its shape, the flow pattern rapidly changes, such as recirculation of flue gas or swirl.

As described above, the fluctuations in the flue gas radically change the amount of evaporation in the high-pressure evaporator 4, reduce the thermal efficiency, destabilize the operation of the steam turbine, and further, heat transfer pipe walls or the heat transfer plate of the high-pressure superheater 3. Local overheating can cause serious troubles for the entire heat recovery steam generator (1) or the overall power generation system, such as pipe wall breakage or pin dropout.

Therefore, in order to equalize the flow pattern of the exhaust gas (GTE) at the inlet of the heat recovery steam generator (1), the flow homogenizing device of the present invention, such as a porous plate which is often installed in a wind tunnel and serves to change the flow of smoke. Also in (11), the exhaust gas passes through the perforated plate and the screen grid 13 by placing the flat perforated plate 12 or the honeycomb and the screen grid 13 in a stacked manner or singly so as to be perpendicular to the flow direction of the exhaust gas. In order to form a uniform flow (Uniform Flow) in the

Therefore, due to the change of gas turbine exhaust gas, the heat absorption of each heat exchanger tube of the evaporator is brought uniformly, and the steam generation rate is kept constant, thereby improving the thermal efficiency and operating the steam turbine stably, and the pipe wall such as the high pressure superheater (3). Breakage and pin dropout can be avoided drastically, and the design of the circulation system of the high pressure superheater (3) and the high pressure evaporator (4), which are the remaining stages of the heat recovery steam generator (1), can be simplified.

The present invention relates to a flow homogenizing device for a heat recovery steam generator, and is provided at an inlet portion of a heat recovery steam generator connected to an exhaust gas outlet of a gas turbine and regenerating waste heat, and is a nonuniformity formed in an outlet exhaust gas of the gas turbine. By eliminating the flow pattern, it prevents pipe wall breakage or fin dropping due to local overheating of the heat transfer pipe wall or the heat transfer fins, and makes the heat absorption of the evaporator uniform, thereby making the steam generation constant and improving the thermal efficiency. It has excellent effects such as enabling driving.

Claims (2)

In the array gas steam generator comprising a high pressure and low pressure superheater connected to the outlet of the gas turbine to receive heat transfer from the incoming exhaust gas and discharge the steam supplied to the steam turbine, a high pressure and low pressure evaporator, and a coal mill, etc. A flow homogenizing device for a heat recovery steam generator, comprising a perforated plate (12) and a screen grid (13), which are dually installed in an exhaust gas flow passage (2), which is a connection passage between the outlet of the turbine and the exhaust gas steam generator (1). The device of claim 1, wherein a honeycomb is used instead of the perforated plate (12).