JPS61235685A - Temperature control device in waste heat retrieving device for thermal plant - Google Patents

Abstract

PURPOSE:To eliminate low-temperature corrosion of a flue due to sulfur content and permit to maintain stabilized combustion of a burner by a method wherein the temperatures of heating fluid and fluid to be heated are controlled so as to be maintained within an allowable range even when there is fluctuation in the load of the plant. CONSTITUTION:The condensing section 10 of a separate type heat pipe heat exchanger is arranged in a line supplying fuel or combustion air to the boiler 1 of the thermal plant and the evaporating section 9 of said heat exchanger is arranged in the line 6 discharging exhaust gas from the boiler while the condensing section 10 and the evaporating section 9 are connected through a circulating pipeline 13 to circulate operating fluid. In such a waste heat retrieving device for the thermal plant, a control valve 15, controlling the circulation of the operating fluid, is provided on the way of the circulation pipeline 13 and a supplying pipeline 16, supplying steam from the outside of the system, is connected to the condensing section 10 of the heat exchanger, further, a discharging pipeline 18, discharging condensed liquid to the outside of the system, is connected to the outlet side of the condensing section 10 while these pipelines 16, 18 are provided with the valves 17, 19, which control the supplying amount of steam and the discharging amount of condensed liquid.

Description

[Detailed Description of the Invention] [Industrial Application Field] The invention relates to a temperature control device in an exhaust heat recovery device of a thermal equipment, and in particular, relates to a temperature control device for a waste heat recovery device of a thermal equipment. The present invention relates to a device that adjusts the temperature of the exhaust gas and fuel or combustion air in a device that recovers exhaust heat held by the exhaust gas into fuel or combustion air supplied to a boiler.

[Conventional technology]

Conventionally, as an exhaust heat recovery device for thermal equipment including a boiler, the evaporation part (heat receiving part) of a heat pipe heat exchanger is placed in the exhaust gas (i.e. heating fluid) line from the boiler, and the heat pipe heat exchanger is used. There is a known device in which the condensing part (heat radiation part) of the boiler is placed in the line of fuel or combustion air (i.e. heated fluid) to the boiler, and the waste heat held by the heated fluid is given to the heated fluid and recovered. There is.

In this exhaust heat recovery device, if the evaporation section and the condensation section are disturbed by a considerable distance from each other, a separate type heat pipe heat exchanger as disclosed in Japanese Patent Publication No. 57-10997, for example, may be used. The operating principle of the separate type heat pipe heat exchanger used is that the evaporating section and the condensing section are connected by two mutually insulated wooden pipes, and the working fluid (
Pure water is usually used. ) flows from the evaporator section through one pipe to the condensing section, and the condensate flows from the condensing section through the other pipe to the evaporation section, thereby causing a working fluid to flow between the evaporation section and the condensation section. It circulates through phase transformation.

[Problem that the invention seeks to solve]

However, in such a conventional waste heat recovery device for heat equipment, when the load on the heat equipment body fluctuates, the exhaust gas and heated fluid, which is the heating fluid of the separate heat pipe heat exchanger, changes accordingly. The temperature and flow rate of certain fuels or combustion air may change, creating undesirable problems.

In particular, when the load on the heat equipment decreases, if the heating fluid is exhaust gas, the flow rate of the exhaust gas decreases and the temperature drops.If the exhaust gas is further recovered by a heat exchanger, the temperature will drop too much. The flue corrodes at low temperatures due to the sulfur content contained in the moon.

In addition, due to a decrease in load, the flow of the heated fluid decreases, and the temperature falls within the allowable range F, causing a change in the flow of fuel from the burner nozzle section of the boiler, resulting in unstable burner combustion. There was a point.

This invention was made in response to the conventional problems [1].In exhaust heat recovery equipment for thermal equipment, the temperature of the heating fluid or heated fluid can be maintained within an allowable range even when the load fluctuates. It is an object of the present invention to provide a temperature control device that can maintain stable combustion in a burner by eliminating low temperature corrosion of the flue due to sulfur content.

[Failure to solve the problem]

Therefore, the temperature control device in the exhaust heat recovery device for heat equipment according to the present invention has a condensing section of a Sepacy 1-type heat pipe heat exchanger arranged in a line that supplies fuel or combustion air to the boiler of the heat equipment, In an exhaust heat recovery device for heat equipment, the evaporation part of the heat exchanger is placed in the line that discharges IJF gas from the boiler, and the condensation part and evaporation part are connected to the circulation piping to circulate the working fluid. In addition to providing a valve to control the circulation of the working fluid in the middle of the heat exchanger, a supply pipe for supplying steam from outside the system is connected to the inlet side of the condensing section of the heat exchanger, and a supply piping for supplying steam from outside the system is connected to the condensing section outlet side of the heat exchanger. A discharge pipe for discharging steam is connected, and a valve is provided in the supply pipe and the discharge pipe to adjust the amount of steam supplied and the amount of condensed liquid discharged.

[Effect]

The function of the temperature control device in the waste heat recovery device of the heat equipment described above is that when the load of the heat equipment is 100% of the normal load, the separate heat pipe ° valve installed in the circulation pipe of the heat exchanger is Then, the valves of the supply piping to the condensing section of the heat exchanger and the valves of the discharge piping from the condensing section are closed, and the exhaust heat recovery device is operated normally to remove the heated fluid from the exhaust gas, which is the heating fluid. Recover waste heat with some fuel or combustion air.

In addition, when the load decreases, the valve of the circulation pipe of the heat exchanger is closed to prevent the heat exchanger from recovering exhaust heat from the exhaust gas, thereby preventing a drop in the temperature of the exhaust gas and at the same time supplying Open the valves of the service piping and the valves of the discharge piping to supply steam from outside the system to the condensing section, and give the latent heat of this steam to the heated fluid, fuel 1:1 or combustion air, to cool the fuel or The temperature of the combustion air is maintained within an allowable range, thereby preventing low-temperature corrosion of the flue due to the sulfur content of the exhaust gas, and maintaining stable combustion in the burner.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, to first explain the configuration, 1 is a boiler that constitutes the heat equipment, 2 is a burner, 3 is a blower that supplies combustion air, and 4 is a combustion air supply that supplies combustion air from the blower 3 to the burner 2. line 5 is a fuel supply line 6 that supplies fuel such as blast furnace gas and coke oven gas to the burner 2;
7 is an exhaust gas line (or exhaust gas flue) that discharges exhaust gas from the boiler 1, and 7 is a chimney, and these constitute the heat equipment.

Reference numeral 8 denotes, for example, a Jungstrom type air preheater, which preheats the combustion air using the exhaust gas from the exhaust gas line 6.

9 is an evaporation part (heat receiving part) of the separate heat pipe heat exchanger, IO is a condensation part (heat radiation part) of the separate heat pipe heat exchanger, 11 is a condensed water tank, and 12 is a circulation pump. are connected in a closed loop by a circulation pipe 13, and a working fluid (steam or pure water) is circulated within the system. This system constitutes an exhaust heat recovery device.

Controls the circulation of the working fluid in the circulation piping 13, for example, between the circulation pump 12 and the evaporation section 9 in the system of the 1F heat recovery device (
Valve 15 that increases/decreases the amount of circulation or stops the circulation
is provided. Further, a supply pipe 16 for supplying steam from outside the exhaust heat recovery device is connected to the inlet side of the condensing part 10,
An intake valve 17 is provided in the middle of the supply pipe 16 to adjust the amount of steam supplied, and a discharge pipe 1 is provided on the outlet side of the condensing part 10 to discharge condensed water from the condensing part IO to the outside of the system.
8 is connected, and a take-out valve 19 is provided in the middle of the discharge pipe 18 to adjust the discharge amount of the condensed water. These constitute a temperature control device.

Next, the operation of the above embodiment will be explained.

When the load of the boiler 1 is 100% of the normal load, the valve 15 of the circulation pipe 13 of the separate heat pipe heat exchanger
is opened, and the intake valve 17 of the supply pipe 16 and the take-out valve 19 of the discharge pipe 18 are closed, and the waste gas is discharged from the exhaust gas to the combustion air 1 or combustion air using the exhaust heat recovery device as usual. ) to recover waste heat.

To explain more specifically, blast furnace gas at a temperature of about 35°C and a flow rate of about 190.000 Nm/H is input from the fuel supply line 5 as a fuel, and a blast furnace gas at a temperature of about 200°C and a flow rate of about 350.0 Nm/H is input from the fuel supply line 5.
0ON m/lI of exhaust gas is discharged from the boiler 1. Then, when the separate heat pipe heat exchanger is operated, the temperature of the exhaust gas decreases to about 130°C, and the blast furnace gas reaches a temperature of about 170°C.

At this temperature of the exhaust gas, low-temperature corrosion of the flue due to its sulfur content does not occur, and at the above temperature of the blast furnace gas, combustion in the burner 2 is stable.

At this time, in addition to the fuel supply tube 5, the coke oven gas is turned on at about 5.60 ON. /H is inserted.

Next, when the load of the boiler 1 decreases to 50%, in the specific example mentioned above, the temperature of the exhaust gas on the inlet side of the evaporator section 9 of the separate heat pipe heat exchanger becomes approximately 160°C, and the load decreases to 100%. When the heat exchanger is operated to recover exhaust heat in the same manner as in the above case, the temperature of the exhaust gas on the outlet side of the evaporator 9 drops to around 100°C. At this time, if fuel with a high sulfur content is used, low-temperature corrosion particularly occurs in the flue.

Therefore, if the operation of the heat exchanger is stopped to prevent the temperature of the exhaust gas from decreasing, the temperature of the exhaust gas will exceed the allowable lower limit, but since the temperature of the blast furnace gas supplied to the burner 2 is low, the combustion of the burner 2 becomes unstable.

Therefore, when the load on the boiler 1 decreases, the valve 15 is closed to stop the operation of the heat exchanger to maintain the exhaust gas temperature within the allowable range, and the intake valve 17 of the supply pipe 16 is opened. Then, steam is supplied from outside the system to the condensing section 10, and the latent heat of the steam heats the blast furnace gas to bring the stomach temperature within the permissible range, thereby maintaining stable combustion of No. 2.

The steam outside the system gives thermal energy to the blast furnace gas, and the condensed water (hot water) is discharged from the discharge pipe 1 by opening the take-out valve 19.
This condensed water is preferably recovered, for example in a turbine condensate system.

In this case, by detecting the temperature of the fuel gas and controlling the steam outside the system, the temperature of the fuel gas can be detected. '+71 degrees of gas can be maintained within the allowable range.

In the embodiments described above, a case has been described in which the exhaust heat held in the exhaust gas is given to the fuel and recovered, but the exhaust heat may be given to the combustion air and recovered.

〔Effect of the invention〕

- As explained above, according to the temperature control device in the exhaust heat recovery device for heat equipment according to the present invention, when the load on the heat equipment is normal, the i1m separate heat pipe heat exchanger is operated as usual. When the load decreases and the exhaust gas temperature drops, the heat exchanger operation is stopped and steam from outside the system is used to recover the exhaust heat held by the exhaust gas into fuel or combustion air. Since the combustion air is heated, it is possible to prevent the temperature of the exhaust gas from decreasing and keep the temperature of the fuel or combustion air within the allowable range, not only when the load is normal but also when the load decreases. Therefore, low-temperature corrosion of the flue due to the sulfur content contained in the fuel can be prevented, and stable combustion of the burner can be maintained.

[Brief explanation of drawings]

The figure is a diagram showing an embodiment of a temperature control device in an exhaust heat recovery device for a thermal facility according to the present invention. 1... Boiler, 4... Combustion air supply line, 5...
...Fuel supply line, 6...Exhaust gas line, 9...
Evaporation section, 10... Condensation section, 13... Circulation piping, 15
...Valve, 16... Supply pipe, 17... Intake valve, 18... Discharge pipe, 19... Take-out valve.

Claims (1)

[Claims] A condensing part of a separate heat pipe heat exchanger is arranged in a line that supplies fuel or combustion air to a boiler of the heat equipment, an evaporation part of the heat exchanger is arranged in a line that exhausts exhaust gas from the boiler, and In an exhaust heat recovery device for thermal equipment configured by connecting a condensing part and the evaporating part by a circulation pipe and circulating a working fluid, a valve for controlling circulation of the working fluid is provided in the middle of the circulation pipe, and a valve for controlling the circulation of the working fluid is provided in the middle of the circulation pipe. A supply pipe for supplying steam from outside the system is connected to the inlet side of the condensing part of the vessel, and a discharge pipe for discharging condensed liquid to the outside of the system is connected to the outlet side of the condensing part. 1. A temperature control device for an exhaust heat recovery device of a heat equipment, characterized in that a valve for adjusting the amount of steam supplied and the amount of condensed liquid discharged is provided in the pipe.