JPS58164907A - Boiler device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiler system, and more particularly to a boiler system provided with means for preventing low-temperature corrosion of an economizer.

When using fuel containing sulfur in the boiler components, the exhaust gas contains sulfur dioxide gas (SO3), and when this exhaust gas comes into contact with low-temperature components, the steam it contains reaches its dew point and condenses. SO3 dissolves into this and turns into sulfuric acid, corroding the parts and causing an accident. Such components include air preheaters, energy savers,
It is known that steel plates and the like that form ducts fall under this category. Among these problems, when water leaks due to corrosion in the heat exchanger tubes of the energy saver that heats the pressurized water supply, there is a problem in that the operation must be shut down, and the energy saver must be repaired or replaced.

This invention can be applied to existing boilers without causing such low-temperature corrosion, and the boiler equipment can be easily modified by adding pipes, etc. Moreover, in new boilers, the feed water heater and heating type deaerator can be easily modified. The purpose of this study is to propose a boiler structure that prevents corrosion of the economizer and eliminates the need for such devices.

In short, this invention bypasses a portion of the water supply □ before entering the economizer and supplies it to the water supply inlet pipe of the drum, and recirculates the heated feed water at the outlet of the economizer. Supply the inlet and control these flow rates: ′,
, :: The present invention is characterized in that the temperature of the water supply at the outlet of the economizer and the temperature of the water supply at the inlet of the economizer are automatically controlled using signals.

FIG. 1 is a diagram showing the sulfur content in heavy oil fuel (the horizontal axis is rust, and the vertical axis is the minimum corrosion-preventing tube metal humidity) when water is flowing inside a carbon steel tube. If there is no scale inside the heat transfer tube, the tube metal temperature can be considered to be approximately the temperature of the fluid inside the tube.Curve (A)
shows the minimum tube metal humidity for preventing corrosion when the fuel does not contain vanadium in the case of a heavy oil-fired boiler, and the curve (
b) Vanadium contained in the combustion residue (ash) is approximately 3
．． The case of 5% is shown.

As is clearer from FIG. 1, the temperature of the fluid (supply water) needs to be higher than this curve.

In conventional boilers, a feed water heater or a heated deaerator was installed as a means of raising the feed water temperature to prevent such low-temperature corrosion, but this resulted in a problem of high equipment costs. 6o, ゛:' The present invention solves this problem by providing a simple feedwater bypass line and recirculation line for the main water supply line.

FIG. 2 is a pipe system diagram showing one embodiment of the present invention.

In this case, water is supplied to the boiler 1 from a water supply tank 2 through a boiler water supply pump 4, a main water flow rate control valve 5, and a main water supply pipe 3 which connects each member to form a main water supply system.
The water is supplied to the upper shell 1a of the boiler via the main water supply flow meter 6 and the energy saver 7. The main water supply conduit 3 consists of a conduit 3a that connects the inlet of the economizer 7 and the water supply tank 2, and a conduit 3b that connects the outlet of the economizer and the upper body 1a. The water supply bypass pipe 8 is provided with a bypass amount adjustment valve (automatic humidity control valve) 9, one end of the water supply bypass pipe 8 is connected to the pipe 3a at a connecting part 8a, and the other end is connected to the drum ( (Upper body) Connect at the nearby connecting part 8b that connects to the inlet.

The feed water recirculation line 10 also connects at one end with the line 3a downstream of the connection 8a for the feed water flow at a connection 10a and at the other end at the connection 1 upstream of the line 3b at the connection 8b.
Connect with 0b. This water supply recirculation line 10 is provided with a recirculation pump 11 and a recirculation amount control valve (automatic humidity control valve) 12.

The combustion gas G flows from the boiler 1 to the economizer 7 via the flue 13, exchanges heat with the feed water, and then flows through the flue 14. It is discharged via the chimney 15.

In such a device, the water supply in the water supply tank 2 is at almost the outside temperature, and if the temperature is 15°C, the heat exchanger tube near the water supply inlet of the economizer will be heated as shown in Fig. 1, regardless of the sulfur content percentage in the fuel. This will cause low-temperature corrosion.

In this case, the bypass water supply amount is controlled from the connection part 8a via the water supply bypass pipe line 8 and the bypass amount control valve (automatic temperature control valve) 9, and the feed water recirculation pipe line 10 is connected to the outlet connection part of the energy saver 7. A part of the heated feed water extracted from 10b is pressurized by a recirculation pump 11, and its flow rate is controlled by a recirculation flow rate control valve (automatic temperature control valve) 12, and the flow rate is controlled by a recirculation flow rate control valve (automatic temperature control valve) 12.
If the water is supplied to the water tank, it mixes with the water supplied from the water supply tank, increases the humidity of the water supply at the inlet of the economizer, and prevents low-temperature corrosion.

In addition, since the water economizer outlet water supply humidity is controlled, the water economizer outlet water temperature can be kept below the saturation temperature for the boiler pressure, causing a water hammer phenomenon in the main water supply pipe including the economizer. This can prevent the occurrence of

The recirculation water supply amount from the recirculation amount control valve 12 is determined by the connection part 10.
A feed water temperature signal from a temperature transmitter 16 installed downstream of the temperature transmitter 16 is sent to the economizer inlet temperature regulator 17, and a recirculation amount control valve (automatic temperature control (valve) 12. Similarly, economizer 7
outlet conduit.

The signal from the temperature transmitter 18 provided at 3b is sent to the economizer outlet temperature regulator 18, and the bypass amount control valve (automatic humidity control valve) 9 is controlled by the command signal.

Figure 3 shows the signal from the exhaust gas hygrometer 21 and the temperature transmitter 1.
6.18 is sent to the main control box 20 of the boiler which stores and issues command signals. A load signal is sent to this main control box 20, and a water supply flow rate signal from the main feed water flow meter 6 is also sent. These signals are compared with the stored values in the main control box, and the main water flow rate control valve 5, bypass amount control valve 9, and recirculation amount control valve 12 are sent to t'7.
1 Command signals are sent and each flow rate is adjusted.

By implementing this invention, the amount of bypass and recirculation of the water supply is controlled, and the humidity of the water supply at the inlet of the economizer is controlled to an appropriate temperature higher than the temperature of the low-temperature corrosion metal, thereby preventing low-temperature corrosion of the economizer and preventing water hammer. This has the effect that it is possible to provide a boiler device that prevents the phenomenon from occurring.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the metal temperature of steel pipes and the sulfur content in the fuel to prevent low-temperature corrosion, Fig. 2 is a pipe system reading diagram of the boiler equipment according to the present invention, and Fig. 3 is It is a drawing showing a control system when each water supply flow rate control valve is controlled by a main control box. 1...Boiler 3...Main water supply pipe:. 3a, 3b1: Pipe line 8... Water supply bypass pipe line 9... Bypass amount control valve (automatic temperature control valve) 1
0... Water supply recirculation pipe (8) 11... Recirculation pump 12... Recirculation amount control valve (automatic temperature control valve) 2
0...Main control box Fig. 1 1C%)

Claims (1)

[Scope of Claims] 1. The main water supply system of the boiler is formed by connecting a water tank, a boiler water supply pump, a main water supply flow rate control valve, a main water supply flow meter, and a energy saver in this order through pipes, and the main water supply system is formed by connecting a water supply tank, a boiler water supply pump, a main water supply flow rate control valve, a main water supply flow meter, and a energy saver in this order. A water supply bypass pipe is provided that connects the downstream water supply pipe and the drum inlet water supply pipe and has a bypass amount adjustment valve in the pipe, and the connection part on the main water flow meter side of this water supply bypass pipe and the energy saver are connected. The main water supply pipe between the inlet and the main water supply pipe on the outlet side of the energy saver is connected, and the water supply recirculation pipe is provided with a recirculation pump and a recirculation amount control valve. boiler equipment. 2. The bypass amount control valve is an automatic temperature control valve that controls the bypass amount of the feed water using the outlet temperature of the economizer as a signal, and the recirculation amount control valve uses the inlet temperature of the economizer as a signal to control the recirculation amount of the feed water. The boiler apparatus according to claim 1, characterized in that it is an automatic temperature control valve that controls the temperature. 3゜ Send the signals of the exhaust gas temperature at the inlet of the economizer, the water supply temperature at the inlet of the economizer, and the water supply temperature at the outlet of the economizer to the main control box of the boiler that outputs memory and command signals, and also sends the boiler load signal and the water supply flow rate signal as described above. It is configured such that the metal humidity of the economizer heat transfer tube can be maintained at a temperature higher than the temperature that causes low-temperature corrosion by sending it to the main control box and controlling the bypass amount adjustment valve, recirculation amount adjustment valve, and main water supply flow rate adjustment valve. A boiler device according to claim 1, characterized in that: