JPH086885B2 - Method for starting exhaust heat recovery heat exchange device and device thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a high temperature exhausted from a gas turbine, a diesel engine, a power generator using a fuel cell, an ironmaking plant, a refuse incineration plant and the like. The present invention relates to a method for starting an exhaust heat recovery heat exchange device that recovers heat from industrial exhaust gas to generate steam, and the device.

(Prior Art) Conventionally, a smoke tube type boiler is often used for an evaporator of a relatively small exhaust heat recovery heat exchange device. Further, when the saturated steam generated in the boiler main body is further heated to generate superheated steam, a superheater is attached. On the other hand, in a smoke tube type boiler, when the feed water temperature is lower than the saturation temperature, a preheater is additionally attached to recover the heat from the exhaust gas that has passed through the evaporator and raise the feed water supplied to the evaporator to near the saturation temperature. It is designed to be warmed. That is, as shown in FIG. 3, the conventional exhaust heat recovery heat exchange device is configured such that the superheater 1, the evaporator 2 and the preheater 3 are arranged in this order from the exhaust gas supply upstream side, and the water supply is performed by the water source valve 12 The saturated steam generated here enters the evaporator 2 by the feed water piping system (pipe line) 15 passing through the preheater 3, and the superheated steam is generated by the steam piping system (pipe line) 16 passing through the superheater 1 and the main steam valve 11. Is supplied to a predetermined place. Exhaust gas is supplied to the evaporator 2 through an exhaust gas piping system 14 that passes through the superheater 1, performs thermal work, and is then discharged to the outside of the system through a preheater 3.

(Problems to be Solved by the Invention) However, in the conventional exhaust heat recovery heat exchange device having the above-described configuration, when heat is generally recovered from industrial exhaust gas,
Exhaust gas as a heat source was often already contaminated. In particular, when the feed water at a temperature close to room temperature is passed through the preheater, there are the following problems. (1) During normal operation (hot start), if feed water having a temperature close to room temperature is passed through the preheater, moisture contained in the exhaust gas will condense on the heat transfer surface such as the heat transfer tube on the exhaust gas side, Furthermore, so-called "sulfuric acid corrosion" is likely to occur, in which sulfurous acid gas or the like is dissolved in the droplets to generate an acid, which significantly corrodes the heat transfer surface.

(2) On the other hand, at the cold start, since no net steam is generated, the superheater and the preheater of the exhaust heat recovery heat exchange device have almost no fluid flow on the water supply side and the water supply side. Therefore, the effective heat transfer part of the heat exchange system is only the evaporator, and it takes a considerable time to complete the startup.

(3) Further, at the cold start, since no steam is generated, the temperature of the heat transfer surface of the superheater becomes close to the temperature of the hot exhaust gas. Therefore, the material is inferior.

The present invention has been made to solve such a problem, and in addition to the water supply piping system and the steam piping system of the conventional exhaust heat recovery heat exchange device, the water supplied to the evaporator (boiler water ) Is supplied to the preheater and the superheater simultaneously or sequentially to the preheater and the superheater, and a method for starting the exhaust heat recovery heat exchange device having a boiler water circulation piping system for returning to the evaporator and its device are provided. I am trying.

[Structure of Invention]

(Means and Actions for Solving the Problem) The present invention has a superheater, an evaporator, and a preheater that are sequentially provided along the flow direction of exhaust gas, and sequentially supplies feed water from the preheater to the evaporator and the superheater. A method for starting an exhaust heat recovery heat exchange device and a device for producing steam by causing the exhaust gas to flow and come into contact with exhaust gas flowing at a heat transfer surface, and a device therefor. The first and second circulation pipes are provided through the circulation pump to the steam outlet side of the device, and at the time of starting the apparatus, first, the feed water accumulated in the evaporator is passed through the first and second circulation pipes to From the preheater to the evaporator and the other from the superheater to the evaporator, they are made to flow to raise the temperature to a predetermined temperature, and then the feed water is sequentially passed from the preheater to the superheater according to the determined route. It is characterized in that it is made to flow to generate steam.

(Embodiment) An embodiment of the exhaust heat recovery heat exchange apparatus of the present invention will be described with reference to FIG.

FIG. 1 shows a system configuration diagram of the exhaust heat recovery heat exchange device, in which the superheater 1, the evaporator 2 and the preheater 3 are arranged in this order from the upstream side of the exhaust gas, and the feed water passes through the feed water source valve 12 and the preheater. Three
The saturated steam generated here enters the evaporator 2 through a water supply piping system (pipe line) 15 that passes through the superheater 1 and the main steam valve 11 through a steam piping system (pipe line) 16 as a superheated steam at a predetermined location. To be supplied to. Further, the industrial exhaust gas is supplied to the evaporator 2 through the exhaust gas piping system (pipe line) 14 passing through the superheater 1, and after performing the work of generating steam, is discharged to the outside of the system through the preheater 3. Has become.

In the exhaust heat recovery heat exchange apparatus of the present invention, in addition to these water supply piping system (pipe) 15, steam piping system (pipe) 16 and exhaust gas piping system (pipe) 14, boiler water circulation piping system (pipe) 5 is provided. That is, this boiler water circulation piping system (pipe line)
As shown in FIG. 1, a superheater 1 includes a boiler water circulation piping system main valve 8, a boiler water circulation pump 4, a flow rate control valve 6, and a superheater supply valve 10 in order from the side connected to the evaporator 2.
From the flow passage that joins the steam piping system 16 on the downstream side and the flow passage that branches on the downstream side of the flow control valve 6 and that joins the water supply piping system 15 upstream of the water supply side of the preheater 3 via the preheater supply valve 9. Become.
Here, the piping system from the evaporator 2 to the feed water inlet side of the preheater 3 is referred to as the first circulation piping or the piping system extending from the steam outlet side of the superheater 1 to the second circulation piping. Also, the water supply piping system
15 is an upstream side of the preheater 3 and has a boiler water circulation piping system 5
A temperature detector 7 is provided downstream of the confluence point with the branch flow path for measuring the inlet water temperature of the preheater, and the valve opening is adjusted in conjunction with the flow rate control valve 6.

The operation of the boiler water circulation piping system (pipe line) 5 thus configured will be described below. First, at the time of normal operation (hot start), when the feed water source valve 12 is opened and the feed water at a temperature close to room temperature is supplied to the feed water piping system 15, the main steam valve 11 is opened and the superheater The supply valve 10 is closed, the preheater supply valve 9 and the boiler water circulation piping system main valve 8 are opened, and the boiler water circulation pump 4 is activated to circulate the boiler water between the evaporator 2 and the preheater 3. Let Further, the feed water temperature at the inlet of the preheater is measured by the temperature detector 7, and the circulating flow rate of the boiler water is adjusted so that the water contained in the exhaust gas does not dew on the heat transfer surface of the preheater 3. The valve opening of 6 is adjusted to mix the feed water and the boiler water at the confluence of the preheater supply valve 9 downstream.

At the cold start, the superheater supply valve 10, the preheater supply valve 9 and the boiler water circulation piping system main valve 8 are opened, and the water supply main valve 12 and the main steam valve 11 are closed. And
The boiler water circulation pump 4 arranged in the boiler water circulation piping system 5 is started to pass the boiler water to the superheater 1 and the preheater 3, and the superheater 1 and the preheater 3 are also effective heat transfer surfaces of the heat exchange system. It is possible to activate the exhaust heat recovery heat exchange device while circulating the boiler water in the boiler water circulation piping system 5.

According to this embodiment, during normal operation of the device (at the time of hot start), the temperature of the feed water flowing into the preheater can be maintained at the dew point or higher, so that corrosion of the heat transfer surface of the preheater is prevented. As a result, the life of the device can be significantly extended. Further, at the time of cold start of this device, the superheater and the preheater act as an effective heat transfer surface of the heat exchange system, so that the time required to complete the startup of the device is significantly shortened.

Another embodiment of the exhaust heat recovery heat exchange apparatus of the present invention is shown in FIG. In FIG. 2, the same components as those of the embodiment of FIG. 1 are basically omitted by using the same reference numerals, and only the differences will be described. In this embodiment, the boiler water circulation piping system 5 including the boiler water circulation piping system main valve 8, the boiler water circulation pump 4, the flow rate control valve 6 and the preheater supply valve 9 is connected to the preheater 3 as viewed from the connection side to the evaporator 2. It joins the water supply piping system 15 on the upstream side. Further, as in the embodiment of FIG. 1, the temperature detector 7
Is installed to measure the inlet water temperature of the preheater. Further, an evaporator supply valve 13 is arranged in the water supply piping system 15 downstream of the water supply side of the superheater 3, and a branch pipe is branched from the upstream pipe of the evaporator supply valve 13 Are joined to the steam piping system 16 downstream of the superheater 1 via the superheater supply valve 10. Here, the pipe system from the evaporator 2 to the feed water inlet side of the preheater 3 is the first circulation pipe, or the pipe system from the feed water outlet side of the preheater 3 to the steam outlet side of the superheater 1 is the second circulation pipe. And Then, as in the embodiment shown in FIG. 1, during normal operation (hot start), the water supply source valve 12 and the main steam valve 11 are opened and the superheater supply valve 10 is closed. , The boiler water circulation piping system main valve 8, the preheater supply valve 9, and the evaporator supply valve 13 are opened, the boiler water circulation pump 4 is started, and the boiler water and the water supply are controlled while adjusting the valve opening of the flow rate control valve 6. While being mixed, water is passed through the preheater 3 to supply water to the evaporator 2. At the cold start, the main valve 8, the flow rate control valve 6, the preheater supply valve 9, and the superheater supply valve 10 are opened,
The main steam valve 11, the water supply source valve 12, and the evaporator supply valve 13 are closed. Then, the boiler water circulation pump 4 is activated so that the boiler water is circulated in the pump water circulation piping system 5 and is sequentially passed through the superheater 1 and the preheater 3 to activate the present apparatus. As a result, dew condensation on the heat transfer surface of the preheater is prevented, and the start-up completion time of the exhaust heat recovery heat exchange device at the cold start is significantly shortened.

〔The invention's effect〕

According to the present invention, since the boiler water circulation piping system is provided in the exhaust heat recovery heat exchange device, corrosion and deterioration of the material of the device constituting the heat exchange system are prevented, and the exhaust heat recovery heat exchange device is required. It has remarkable effects such as a significant reduction in startup time.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the exhaust heat recovery heat exchange device of the present invention, FIG. 2 is a system configuration diagram of another embodiment of the exhaust heat recovery heat exchange device of the present invention, and FIG. 2 is a system configuration diagram of the exhaust heat recovery heat exchange device of FIG. 1 ... Superheater, 2 ... Evaporator, 3 ... Preheater, 4 ... Boiler water circulation pump, 5 ... Boiler water circulation piping system (pipe line), 6 ... Flow control valve, 7 ... Temperature detector , 8 …… Boiler water circulation piping main valve, 9 …… Preheater supply valve, 10 …… Superheater supply valve, 11 …… Main steam valve, 12 …… Water supply main valve, 14 ……
Exhaust gas piping system (pipe), 15 ... Water supply piping system (pipe), 16
...... Steam piping system (pipe line).

Claims (4)

[Claims] 1. A superheater, an evaporator and a preheater which are sequentially provided along a flow direction of exhaust gas, wherein feed water is made to sequentially flow from the preheater to the evaporator and the superheater, and a heat transfer surface separates them. In a method for starting an exhaust heat recovery heat exchange device, which is adapted to generate steam by contacting with exhaust gas flowing therethrough, first and second parts are provided from the evaporator to the feed water inlet side of the preheater and the steam outlet side of the superheater. 2 circulation piping is provided via a circulation pump to start the device,
First, the feed water stored in the evaporator is made to flow through the first and second circulation pipes, one from the preheater to the evaporator, and the other from the superheater to the evaporator to flow to a predetermined temperature. The method for activating an exhaust heat recovery and exchange apparatus is characterized in that the feed water is sequentially flowed from the preheater to the superheater according to a predetermined route to generate steam. 2. A superheater, an evaporator and a preheater which are sequentially provided along a flow direction of the exhaust gas, wherein feed water is made to sequentially flow from the preheater to the evaporator and the superheater, and a heat transfer surface separates them. In a method for starting an exhaust heat recovery heat exchange device, which is adapted to generate steam by contacting with exhaust gas flowing therethrough, first and second parts are provided from the evaporator to the feed water inlet side of the preheater and the steam outlet side of the superheater. A starting device for an exhaust heat recovery heat exchange device, wherein the second circulation pipe is provided via a circulation pump. 3. A superheater, an evaporator, and a preheater which are sequentially provided along a flow direction of exhaust gas, wherein feed water is made to sequentially flow from the preheater to the evaporator and the superheater, and a heat transfer surface separates them. In the starting method of the exhaust heat recovery heat exchange device which is brought into contact with flowing exhaust gas to generate steam, from the evaporator, from the feed water inlet side of the preheater and the feed water outlet side of the preheater of the superheater. First and second circulation pipes are provided to the steam outlet side through a circulation pump, and at the time of starting the apparatus, first, the feed water accumulated in the evaporator is passed through the first circulation pipe, and then the second circulation pipe. It is made to flow through the circulation pipe from the preheater to the superheater in order to raise the temperature to a predetermined temperature.After that, feed water is made to sequentially flow in accordance with a predetermined route from the preheater to the superheater to generate steam. Starting the exhaust heat recovery heat exchanger being characterized in that so as to formed. 4. A superheater, an evaporator, and a preheater which are sequentially provided along a flow direction of exhaust gas, wherein feed water is made to sequentially flow from the preheater to the evaporator and the superheater, and the water is separated by a heat transfer surface. In the starting method of the exhaust heat recovery heat exchange device which is brought into contact with flowing exhaust gas to generate steam, from the evaporator, from the feed water inlet side of the preheater and the feed water outlet side of the preheater of the superheater. A starting device for an exhaust heat recovery heat exchange device, characterized in that first and second circulation pipes are provided to a steam outlet side via a circulation pump.