JP2006274624A - Road heating facility and its operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road heating facility and its operating method for effectively utilizing generated output and heated effluent by a fuel cell for melting snow. <P>SOLUTION: The road heating facility wherein a heating unit using an electric heater and a heating unit using a hot water pipe are buried under the surface of a road or its analogue, comprises a feeder device and a heat source device connected to the respective units to control the amount of heat generation. The feeder device and the heat source device are arranged in a fuel cell cogeneration system, and the electric heater is preferably laid to gradually increase from the upstream side toward the downstream side of the heating unit using the hot water pipe. In the operating method, the stand-by operation of predetermined output is performed for a predetermined time before the anticipated time of snowfall, and the preheating operation of the heating unit can be performed with its electric power and exhaust heat. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a road heating facility using a fuel cell cogeneration system for melting and removing snow and ice on the surface of roads or the like, such as stairs, parking lots and entrances, and a method for operating the same.

In general, load heating equipment calculates the design calorific value set to cope with most snowfalls based on the past weather conditions at the installation location, etc., and the heating heating unit (electric heater) generates heat from the load heating area. The snow melting ability of the heat source device for the heat generating unit by the power feeding device or the hot water pipe is determined.
In particular, load heating equipment using hot water pipes with a heat source device is said to have a great merit in terms of cost, and has been introduced in many places.
When snowfall is detected in the severe cold season and snow melting is started with the designed heat amount, the road surface temperature is often further lowered than the temperature leading to snow melting. Therefore, in a snow melting facility having an equipment capacity determined from the snow melting capacity, it may take several hours to reach the snow melting temperature.

In road heating, it is one of the important issues to shorten the time until the road surface temperature reaches the snow melting temperature from the temperature at the start of snow melting.
A fuel cell that uses natural gas or the like as a fuel to reform it into a gas rich in hydrogen, generates electricity through an electrochemical reaction between the hydrogen and an oxidant such as air, and can use exhaust heat that is almost equivalent to the amount of power generated. Low pollution, low noise level, and future development as a cogeneration device is expected. In general homes and the like, the generated power is supplied to various electric loads in the home, and this exhaust heat is stored in a hot water tank and used for hot water demand in a bathtub or kitchen.
In cold regions, winter snow cover is an important issue to ensure walking and traffic safety.
Generally, a road heating facility is a snow melting facility that melts snow by supplying commercial power to a heating wire (electric heater) installed in the basement, or a hot water distribution pipe in the basement to supply hot water made by a boiler. Snow melting facilities that supply and melt snow are known.
Japanese Patent Laid-Open No. 2004-100347 JP 2001-228263 A Japanese Patent No. 2825443

  It is an object of the present invention to provide a road heating facility and an operation method thereof that can effectively use the generated power and hot drainage of the fuel cell cogeneration system for melting snow instead of these snow melting facilities.

In order to solve the above problems, in the present invention, a heat generation unit using an electric heater and a heat generation unit using a hot water pipe are embedded in the lower surface of a road or the like and connected to each unit to control the amount of heat generation. A load heating facility including a power supply device and a heat source device, wherein the power supply device and the heat source device are provided in a fuel cell cogeneration system.
In the load heating facility, the heat generating unit using an electric heater can be laid so that the heating capacity gradually increases from the upstream side to the downstream side of the heat generating unit using the hot water pipe, and the fuel cell. The cogeneration system can be a fuel cell cogeneration system using a polymer electrolyte fuel cell.
Further, according to the present invention, in the operation method of the road heating facility, based on weather information, the fuel cell cogeneration system is activated and a standby operation with a predetermined output is performed before a predetermined time when snowfall is expected. The heating method of the road heating equipment is characterized in that preheating operation of the two heat generating units is performed by using electric power and hot exhaust heat.

According to the present invention, even in a polymer electrolyte fuel cell having a relatively short start-up time, it usually takes 40 to 60 minutes for temperature rise of the fuel reformer from start-up to rated operation. If it is predicted that snowfall will occur, a fuel cell start command will be given a predetermined time before the predicted time, and preheating will be performed prior to snowfall as a partial load state (standby operation state) before snowfall Can do. By doing this, when snowfall is detected, the time to reach rated operation can be significantly shortened, and the ground temperature has risen to some extent due to preheating by standby operation in advance. It will be possible.
The melting of snow by the power generated by the fuel cell and the melting of snow by hot water are designed according to the local conditions. When the prediction is in accordance with the predicted situation, the fuel cell system will perform rated operation. If it is determined that the snow melting capacity is sufficient, control can be performed to reduce the power generation output of the fuel cell, and the amount of heat supplied by hot water should be reduced in proportion to the reduction in generated power. Can do.

The present invention is generally applied to a road heating facility, that is, a snow melting facility that melts snow by supplying commercial power to an electric heating wire (electric heater) laid underground, or a hot water distribution pipe laid underground. It is a system that effectively uses the generated power and hot drainage of the fuel cell cogeneration system for melting snow instead of a snow melting facility that melts snow by supplying warm water.
As described above, the fuel cell cogeneration system generates electricity through an electrochemical reaction between hydrogen and an oxidant such as air, and can use exhaust heat that is almost equivalent to the amount of power generation. It is a generation system, and it is possible to operate with high overall efficiency (generally 80% or more) as a fuel cell system by simultaneously using this generated power and hot waste water for melting snow.

In general households, when using this fuel cell cogeneration system, so-called heat main power operation is common, and operation is performed to stop power generation when the amount of stored heat is full. In a snow melting facility using fuel cell cogeneration, all of its electric power and hot water can be used for snow melting, so there is no need to perform power generation control according to electric power or hot water demand.
Moreover, in the season which does not require snow melting other than winter, it can be used as a normal cogeneration system, for example, as a power supply to a household power load and a hot water supply facility for a bath or kitchen.
Further, in the present invention, the heating capability of the heating unit by the heating wire (electric heater) is laid so as to gradually increase from the upstream side to the downstream side of the heating unit by the hot water pipe. In the snow melting equipment by laying hot water pipes, the hot water temperature is high on the upstream side, but as the temperature goes to the downstream side, the temperature decreases and the snow melting ability decreases, so-called “snow melting unevenness” occurs.

In order to solve this problem, the present invention is laid so as to increase the heating capacity of the heating unit by the heating wire (electric heater) from the upstream side to the downstream side of the heating unit by the laid hot water pipe. In addition, it is possible to compensate for a decrease in snow melting ability on the downstream side of the heat generating unit by the hot water pipe, and to avoid “uneven snow melting”.
When a hydrocarbon-based fuel such as natural gas is reformed to generate a gas rich in hydrogen and power is generated using this as a fuel, for example, in a polymer electrolyte fuel cell, it takes time to increase the temperature of the reformer. However, it usually takes 40 to 60 minutes from start to rated power generation, and even if the start is performed when snowfall is recognized, there is a delay in the supply of electric power and hot water, and it is not possible to quickly go to snow melting operation. There is a point.

In the present invention, in a snow melting facility using a fuel cell cogeneration system, a gas rich in hydrogen is generated by reforming a hydrocarbon fuel such as methane, and snow is detected in a system that generates electricity using the gas as a fuel. It takes into account the time delay from the start to the rated operation.
Based on weather information such as weather forecasts, when snowfall is predicted, the system is started before a predetermined time considering the rise time of the fuel cell cogeneration system, and until snowfall is detected, Perform partial load operation (which is said to be about 30% of the rating in a normal system) where the power generation efficiency of the fuel cell does not extremely decrease, and use the electric power and hot drainage generated by this partial load operation to It is intended to preheat.

By doing this, when snowfall is detected, the fuel cell system is already in the standby operation state, so that the operation can be quickly shifted to the rated operation, and the remaining heat is generated using the electric power and hot water generated from the partial load operation. Since it is being carried out, it is possible to immediately shift to snow melting operation.
It is also possible to perform a standby operation in which only the reformer is kept in a hot state without generating power in the fuel cell itself. In this case, preheating is not performed, but the time to rated operation can be shortened.
In the present invention, the fuel cell cogeneration system uses a fuel cell cogeneration system using a polymer electrolyte fuel cell. The polymer electrolyte fuel cell has an advantage that its operating temperature is shorter than that of other types of fuel cells.

Next, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a snow melting system according to the present invention. Electric power generated by a fuel cell is used for heat generation by a heater, and is obtained by heat exchange (described later) with a stack and combustion exhaust gas. The heated water is supplied to the laid snow melting pipeline. The hot water that has become cold due to melting snow is returned to the fuel cell cogeneration system.
FIG. 2 is another schematic diagram for explaining the snow melting system according to the present invention, in which the heating capability of the heating unit by the heating wire (electric heater) is from the upstream side to the downstream side of the heating unit by the hot water pipe. It is laid to gradually increase. In this figure, the heating capacity is gradually increased from the upstream side of the heating unit by the hot water pipe to the downstream side by changing the laying density of the heating wire, but from the upstream side of the heating unit by the hot water pipe. The heating capacity may be gradually increased from the upstream side to the downstream side of the heating unit by the hot water pipe by using a heating wire having a large heating capacity toward the downstream side.

FIG. 3 is a diagram for explaining the operation method of the fuel cell cogeneration system and the snow melting system, omitting valves and other devices unnecessary for the explanation.
The fuel cell cogeneration system includes a fuel cell power generation system and a cogeneration system that uses exhaust heat from the system. The fuel cell system performs steam reforming and carbon monoxide conversion on hydrocarbon fuels typified by natural gas, and also removes carbon monoxide in the case of solid polymer fuel cells. These fuels are rich in hydrogen. Fuel reformer that reforms into gas, stack that performs electrochemical power generation using the reformed gas and air as fuel, converter that converts generated power and supplies it to load, fuel cell control unit, and heat exchanger And auxiliary equipment (partially not shown) such as a circulation pump and a valve.

The heat exchanger 1 is for lowering the gas temperature by exchanging exhaust heat of the combustion exhaust gas, and the heat exchanger 2 is used for exhausting heat generated by the stack accompanying power generation. The stack itself is cooled by an indirect heat exchange system in order to avoid an increase in electrical conductivity inside, and pure water is usually used for the stack cooling water line.
The power converted into AC power by the converter is normally linked to a commercial power source and is used by being connected to a general load such as a lighting / electric appliance in the home.
A normal hot water tank is installed outside the fuel cell system, and the water in the hot water tank is circulated to the heat exchangers 1 and 2 by the hot water tank circulation pump, where heat is exchanged and becomes hot water. Returned to the tank.
For example, since warm waste water from a polymer electrolyte fuel cell is discharged at about 60 to 70 ° C., it is diluted and supplied to an appropriate temperature by a mixing unit depending on the intended use. In addition, when the temperature of the hot water in the hot water tank is low, it may be supplied after being heated (so-called additional cooking) by a water heater.

In general fuel cell cogeneration systems, so-called heat main / electric slave operation is generally performed, and the operation is started according to the power load condition and the power load following operation is performed. When the hot water storage tank is full, the operation is stopped.
In the fuel cell cogeneration system having the snow melting system shown in FIG. 3, in addition to the above-described configuration, a load switching device that switches between a general load and a snow melting load, and a three-way switching the circulation return line to the hot water tank to the snow melting line A valve and a controller for controlling them. The control device may be configured as a part of the fuel cell control device.

During normal operation, the fuel cell is generating electricity and storing heat in the hot water storage tank. When it is determined that snow melting is necessary, the load switching device loads the snow melting heater. Switch to the side and feed power to the snowmelt heater. Hot water in the hot water tank circulation line is supplied to the snow melting pipeline by switching the three-way valve. The hot water that has fallen due to the melting of snow is returned to the lower part of the hot water tank, heated again, and circulated.
It is also preferable to use a signal from a snowfall sensor for switching operation.

  When the fuel cell is stopped, the load switching device switches the load to the snow melting heater, switches the three-way valve to the snow melting pipeline, starts the hot water tank circulation pump, and issues a start command to the fuel cell power generation system. To do. By doing so, when hot water is stored in the hot water storage tank, this hot water can be used for preheating until the fuel cell power generation reaches the rating.

The schematic diagram which shows an example of the snow melting system of this invention. The schematic diagram which shows the other example of the snow melting system of this invention. The flow block diagram which shows an example of the fuel cell cogeneration system used for this invention.

Claims (4)

  Road heating provided with a power supply device and a heat source device that embeds a heat generating unit using an electric heater and a heat generating unit using a hot water pipe under the surface of a road or the like, and controls the amount of heat generated by connecting to each unit. A road heating facility, wherein the power supply device and the heat source device are provided in a fuel cell cogeneration system.   2. The road heat according to claim 1, wherein the heat generating unit using the electric heater is laid so that a heating capacity gradually increases from an upstream side to a downstream side of the heat generating unit using the hot water pipe. Equipment.   The road heating facility according to claim 1 or 2, wherein the fuel cell cogeneration system is a fuel cell cogeneration system using a polymer electrolyte fuel cell.   In the operation method of the road heating equipment according to claim 1, 2, or 3, based on weather information, the fuel cell cogeneration system is activated and a standby operation of a predetermined output is performed before a predetermined time when snowfall is expected, A method for operating a road heating facility, wherein the two heating units are preheated using electric power and hot exhaust heat in standby operation.

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