JP2003243019A - Waste power generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste power generating system clean and having high power generation efficiency. <P>SOLUTION: This waste power generating system is equipped with a pyrolysis furnace 1 generating pyrolysis gas by heating waste; a reforming furnace 2 removing tar, soot, or the like in the pyrolysis gas; a gas purification device 4 removing oxidizing gas components such as sulfur components, chlorine components in the reformed gas; and a fuel cell 5 generating power by supplying purified gas. The power generating system also has an exhaust heat recovering facility, and the exhaust heat generating in the fuel cell 5 is used as a heat source of the pyrolysis furnace 1, or high temperature steam is used as heat source and a steam source of the reforming furnace 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste power generation system for generating power from wastes containing organic substances such as general wastes (city waste, septic tanks, sewage sludge, etc.) and industrial wastes, and more particularly to fuels. The present invention relates to a waste power generation system that uses batteries to generate power.

[0002]

2. Description of the Related Art In recent years, problems associated with incineration and landfill treatment of general waste and industrial waste (environmentally influential substances represented by dioxins, securing landfill disposal sites, etc.) are becoming more serious. . Under such circumstances, research and development related to the effective utilization of unused energy, reduction of waste, extension of life of landfill disposal sites, and the recycling of waste in order to solve the above-mentioned problems in waste disposal are advanced. As a part of this, waste power generation technology using waste as a raw material is drawing attention.

[0003] Conventionally, as such a waste power generation system, a method of producing steam by using waste as a heat source of a boiler and generating power with a steam turbine generator, or throwing waste into a gasification and melting furnace to combustible gas ( Pyrolysis gas) is generated, and the purified gas is used to generate electricity with a diesel engine generator or a fuel cell.

[0004]

By the way, looking at the power generation efficiency by each of the above-mentioned power generation methods, the method using the steam turbine generator is at most 25%, the method using the diesel engine generator is at most 30%, and the fuel cell is The method used is at most about 35%, which is extremely low in power generation efficiency. Therefore, in order to obtain abundant power generation for practical use, a large-scale power generation system capable of supplying and processing a large amount of waste at one time. I had no choice but to take the form of. In the case of a fuel cell, a relatively high power generation efficiency of about 55% can be obtained by itself, but in the case of waste power generation, a heat source for gasifying waste is required. It will be about 35% at best.

Further, in the case of a steam turbine generator or a diesel engine generator, there is a problem of environmental pollution due to nitrogen oxides (NOx), sulfur oxides (SOx), soot and the like discharged to the outside, noise and vibration. There was a problem, and in addition, there was a problem that complicated and large-scale equipment was required for these measures. The larger the scale of waste treatment (that is, the scale of the power generation system), the more serious such a problem becomes.

An object of the present invention is to solve the conventional problems and provide a small-scale waste power generation system capable of distributed processing and having high power generation efficiency.

[0007]

[Means for Solving the Problems] That is, according to the present invention as set forth in claim 1, a pyrolysis furnace for heating waste to generate a pyrolysis gas, a tar or soot, a sulfur content in the pyrolysis gas and A reforming facility that removes chlorine and the like to purify a hydrogen-rich gas, and a fuel cell that supplies purified gas to generate power, and further, exhaust heat generated from the fuel cell is used as a heat source of the pyrolysis furnace. It is characterized by having exhaust heat recovery equipment for use.

The present invention according to claim 2 further comprises a pyrolysis furnace for heating waste to generate pyrolysis gas, and removing tar, soot, sulfur and chlorine in the pyrolysis gas. A reforming facility for purifying a hydrogen-rich gas and a fuel cell for supplying purified gas to generate power, and for using exhaust steam generated from the fuel cell as a heat source and a steam source for the reforming facility. It is characterized by being equipped with exhaust heat recovery equipment.

The present invention as set forth in claim 3 removes tar and soot, sulfur content, chlorine content and the like in the pyrolysis furnace that heats waste to generate pyrolysis gas. A reforming facility for purifying a hydrogen-rich gas, and a fuel cell for supplying a purified gas to generate electric power. Further, exhaust heat generated from the fuel cell is used as a heat source for the pyrolysis furnace, and exhaust steam is also used. Is provided with an exhaust heat recovery facility for using as a heat source and a steam source of the reforming facility.

The present invention according to claim 4 is the waste power generation system according to any one of claims 1 to 3, wherein the fuel cell is arranged in an appropriate position in the pyrolysis furnace. It is characterized by that.

According to a fifth aspect of the present invention, in the waste power generation system according to any of the first to fourth aspects, the fuel cell is a high temperature solid oxide fuel cell. It is characterized by that.

In the waste power generation system having the above structure, the exhaust heat of the fuel cell is used as a heat source for pyrolysis gasification (for example, preheating of combustion air, predrying of waste having a large water content, etc.). The thermal efficiency of the decomposition furnace can be improved. In this case, it is efficient to install a fuel cell, which is a heat source, inside the pyrolysis furnace. As a fuel cell, the operating temperature is 500 to 1
It is preferable to use a solid oxide fuel cell at 100 ° C. By using the fuel cell with the above operating temperature, the combustion heat generated in the furnace is raised when the temperature of the cell is raised (The fuel cell generates electricity by a chemical reaction, so it is necessary to raise the internal temperature to an appropriate temperature when starting. Can be used as a heating source
The fuel cell main body does not require a heater facility or the like dedicated to raising the temperature.

Further, since the heat and steam discharged from the fuel cell side are used for the endothermic reaction when reforming the pyrolysis gas, the exothermic reaction for supplying the thermal energy can be suppressed as much as possible.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, the waste power generation system of the present embodiment comprises a pyrolysis furnace 1 (gasification and melting furnace), a reforming furnace 2 constituting a reforming facility, a heat exchanger 3 and a gas purifying apparatus. 4 and
A fuel cell 5 and a heat exchanger 6 that constitutes a facility for recovering exhaust heat and the like.
It is basically composed of a condenser 7 and a condenser 7.

The pyrolysis furnace 1 heats the waste, which is charged together with coke, limestone, etc., in a reducing atmosphere to pyrolyze the pyrolysis gas (combustible gas) and the residue (ash and metal). Of the furnace. Generally, a heat source for thermal decomposition can be obtained by burning a part of waste. Combustion air with a considerably reduced flow rate is supplied to the pyrolysis furnace 1, but if this air is preheated to a high temperature, the temperature inside the gasification furnace is increased by that much,
The calorific value of the pyrolysis gas can be increased. The pyrolysis gas is taken out from the upper part of the pyrolysis furnace 1, and the residue is taken out from the lower part of the pyrolysis furnace 1.

In the reforming furnace 2, CO contained in the pyrolysis gas
Or H ₂ , CO ₂ , soot, Cl ₂ , SO ₂ etc.
Unnecessary combustible components (solid particles) such as tar and soot are removed. Steam heated with pyrolysis gas is injected into the reforming furnace 2, and in the present embodiment, tar and soot are gasified into CO and H ₂ by a known steam reforming method.

The reaction of this steam reforming method is as follows. Reforming reaction (endotherm) C + CO ₂ → 2CO C + H ₂ O → 2CO + H ₂ C _n H _m + nH ₂ O → nCO + (n + 1/2 ・ m) H ₂ exothermic reaction C + O ₂ → CO ₂ C + 1/2 ・ O ₂ → CO This exothermic reaction is necessary for the reforming reaction, for example, 8
It is a reaction that occurs to replenish heat above 00 ° C.
Oxygen (or air) participating in this reaction is supplied together with the steam for the reforming reaction described above.

In the gas purifier 4, Cl ₂ , SO _{2 and the} like contained in the reformed gas from the reforming furnace 2 are removed. The reformed gas from the reforming furnace 2 is cooled through a heat exchanger 3 and then sent to a gas refining device 4 to reduce the content of sulfur, chlorine, and the like to 1000 ppm or less, and further to the heat exchanger 3 Is heated and refined into a hydrogen-rich gas (including CO etc.).

The hydrogen-rich purified gas obtained in the gas purification device 4 is sent to the fuel cell 5. Known fuel cells such as molten carbonate type (MCFC), phosphoric acid type (PAFC), solid polymer type (PEFC), and solid oxide type (SOFC) can be used as the fuel cell.
A high temperature type solid oxide fuel cell such as 00 to 1100 ° C. is used.

The so-called solid oxide fuel cell 5 has oxygen (air) on the air electrode side and fuel gas (H ₂ , CO ₂ ) on the fuel electrode side.
Etc.) is supplied, and a direct electric output is obtained by continuously reacting the fuel electrochemically. The electric output (DC current) of the fuel cell 5 is used as it is or after being converted into AC through an inverter and used inside and outside the system of the present invention. H ₂ O, CO _{2 and the} like are produced as reaction products.

Incidentally, the electrode reaction when H ₂ is used as the fuel is as follows. Air electrode: 1/2 O ₂ + 2e ⁻ → O ^{2 −} Fuel electrode: H ₂ + O ² → → H ₂ O + 2e ⁻ Overall: H ₂ + 1/2 O ₂ → H ₂ O

On the other hand, high-temperature steam, air, CO _{2 and the} like discharged from the fuel cell 5 are once cooled through the heat exchanger 6 into water, and separated into water, air and CO ₂ by the condenser 7. To be done. Among them, air and CO ₂ are exhausted to the outside, water is recovered and heated again through the heat exchanger 6, and 800 required for the exothermic reaction in the reforming furnace 2 is performed.
It becomes high temperature steam above ℃. Since the amount of CO ₂ exhausted is very small and most of it is H ₂ O, an extremely clean power generation system that does not harm the environment can be constructed.

The heated steam is sent to the reforming furnace 2 and used as the steam for the reforming described above and also as the heat energy for the endothermic reaction.
As a result, the exothermic reaction for supplying heat energy can be suppressed as much as possible, the oxygen (or air) supply mechanism to the reforming furnace 2 can be simplified, and the reforming equipment can be made compact.

On the other hand, the exhaust heat from the fuel cell 5 is sent to the pyrolysis furnace 1 and is efficiently used as a heat source for gasification (preheating combustion air, heat source for predrying waste with high water content, etc.). Is used for. Thereby, the thermal efficiency of the thermal decomposition furnace can be improved, and the power generation efficiency of the entire system can be improved to 45 to 50%.

Although not shown, the fuel cell 5 is placed in a suitable position in the thermal decomposition furnace 1, for example, a gasification zone in the furnace (an upper part of a waste layer deposited at the bottom of the furnace, and a decomposition gas generated by heating is generated). The heat of combustion in the furnace can be used as a heating source for raising the temperature of the fuel cell to 500 to 1100 ° C.

Thus, the thermal energy (exhaust heat) generated in the system during power generation and the by-products are effectively discharged in the system without being discharged to the outside.
A highly efficient, safe, and clean power generation system can be constructed, and it is targeted for small and medium-sized applications such as the expected daily waste disposal amount of tens of tons or less (factory, hospital,
This will enable the realization of distributed waste power generation systems such as hotels, office buildings, general households, etc.

[0028]

As described above, according to the present invention,
Since the exhaust heat generated from the fuel cell was used as the heat source of the pyrolysis furnace and the exhaust steam was used as the heat source and steam source of the reforming equipment, the thermal efficiency of the pyrolysis furnace was improved and the power generation efficiency of the system was improved. . As a result, it is possible to realize a small-to-medium-scale distributed waste power generation system with a daily waste disposal amount of several tens of tons or less.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a waste power generation system according to this embodiment.

[Explanation of symbols]

1 Pyrolysis furnace 2 reforming furnace 4 gas purification equipment 5 Fuel cells (solid oxide fuel cells) 3, 6 heat exchanger 7 condenser

Claims (5)

[Claims] 1. A pyrolysis furnace that heats waste to generate pyrolysis gas, and a reformer that removes tar and soot, sulfur and chlorine in the pyrolysis gas, and purifies a hydrogen-rich gas. Disposal characterized by comprising equipment and a fuel cell for supplying purified gas to generate power, and further comprising exhaust heat recovery equipment for using exhaust heat generated from the fuel cell as a heat source of the pyrolysis furnace Power generation system. 2. A pyrolysis furnace that heats waste to generate pyrolysis gas and a reformer that removes tar and soot, sulfur and chlorine in the pyrolysis gas, and purifies a hydrogen-rich gas. And an exhaust heat recovery facility for using the exhaust steam generated from the fuel cell as a heat source and steam source of the reforming facility. And waste power generation system. 3. A pyrolysis furnace that heats waste to generate pyrolysis gas, and a reformer that removes tar and soot, sulfur content, chlorine content, etc. in the pyrolysis gas to purify a hydrogen-rich gas. Equipment and a fuel cell for supplying purified gas to generate electric power, further using exhaust heat generated from the fuel cell as a heat source of the pyrolysis furnace, and using exhaust steam as a heat source and steam source of the reforming equipment. A waste power generation system, characterized in that it is provided with an exhaust heat recovery facility for use in. 4. The waste power generation system according to any one of claims 1 to 3, wherein the fuel cell is arranged in an appropriate place in the pyrolysis furnace. 5. The fuel cell according to claim 1, wherein the fuel cell is a high temperature solid oxide fuel cell.
The waste power generation system according to any one of 1 to 3.