FR2733303A1 - Combined heater and waste burner - Google Patents

Abstract

The heater and burner comprises a hearth (2) into which a fuel is placed. the burner has a grill (3) to receive the waste to be burned. A heat exchanger (4) is positioned in the central part of the burner to heat a fluid in the exchanger. There is a chimney (6) in the upper part for the evacuation of the products of combustion. The heater can include at least two burners (21,23) for staged combustion. The fuel for the burners can be a liquid fuel supplied to the burners in the presence of an oxidising fluid.

Description

 The subject of the invention is a boiler intended for heating a fluid, in particular for producing heating water or domestic hot water intended for family use, preferably operating on natural gas and suitable for also being used as an incinerator. particularly household waste.

 At present, especially in highly industrialized countries, it is becoming increasingly necessary to transform waste, in particular to meet environmental protection and waste recovery requirements.

 For household waste, the quantity of which is only increasing, numerous problems arise concerning collection, storage, sorting, treatment, recovery. Many attempts are made to improve the economic and ecological efficiency of the entire chain.

 The solution of the invention consists of a boiler capable of treating the combustible elements that can be recovered by incineration.

This waste boiler-incinerator comprises in its lower part a hearth into which fuel is introduced and where a grid receiving the waste to be incinerated is arranged, an exchanger in the central part for heating a fluid circulating in the exchanger using combustion products from the fireplace, a chimney in its upper part for the evacuation of combustion products.

To solve the general problem, the invention also proposes a method of operating a boiler-incinerator in which:
- heating by combustion products generated by combustion at the location of at least one combustion zone at least one exchanger in which circulates a fluid to be heated,
- And the place of at least this waste combustion zone is incinerated, the heat produced by this incineration completing the heating of said exchanger.

 Household waste being composed of approximately 70% of combustible materials including approximately 50% of paper, cardboard and vegetable materials, the invention therefore has significant ecological potential and consequent possibilities of supplying combustible material.

 In addition, in the "residential" context for an individual or for a reduced community such as a building, it encourages the sorting of waste at source, desirable for a global treatment and a global recovery of more efficient waste. it makes sorting at source appear to be less restrictive, it does not generate the cost of collecting waste or the cost of distributing incineration energy for a large part of the waste produced, and raises awareness individuals or communities using this solution to the problem of waste treatment, that they are directly beneficiaries.

 Another characteristic of the invention aims to improve the incineration of waste. For this, the boiler-incinerator comprises at least two burners for achieving staged combustion, the fuel being constituted by a combustible fluid supplying said burners in the presence of oxidizing fluid.

As part of the process, the solution is that combustion takes place in two stages between which the waste is placed:
- one upstream from the direction of propagation of the combustion products, where the conditions are particularly favorable for incineration,
- the other downstream, where the combustion products from the upstream stage are re-burned.

 Another characteristic of the invention aims to reduce polluting emissions. For this, the combustion takes place in excess of oxidizing fluid relative to the fuel on the upstream stage, and in the absence of oxidizing fluid relative to the fuel on the downstream stage. The re-burning operation carried out in the downstream area makes it possible to reduce polluting emissions based on nitrogen oxides, in particular while improving the conditions for incineration of waste upstream.

Another characteristic of the invention aims to store waste under good security conditions. For this, the boiler includes a system for introducing waste into the home, comprising:
- an entry airlock for the storage of waste,
- Means for bringing waste from the airlock to the hearth, these feeding means having a passage section smaller than that of the airlock, and isolating the airlock from combustion in the hearth. This system makes it possible to gradually introduce the waste so as to manage its incineration as required by isolating it in the airlock of the combustion chamber.

 Another characteristic of the invention aims to facilitate the incineration of waste. For this, the waste introduction system comprises a crusher placed between the airlock and the supply means. The shredding of waste such as paper and cardboard significantly promotes their combustion.

 Another characteristic of the invention consists in a preferred embodiment of the supply means constituted by a supply screw mounted tightly in the body in which it rotates. This solution makes it possible to control the arrival of waste and prevents the flames from rising in the airlock. It is also possible to compact favorably (without excess) the waste to be incinerated.

Other characteristics and advantages of the invention will appear from the description which follows, given with reference to the appended drawings, representing an incinerator boiler according to different variant embodiments and in which:
FIG. 1 represents a first embodiment of an incinerator boiler,
FIG. 2 represents a second embodiment of an incinerator boiler,
- Figure 3 shows a third embodiment of an incinerator boiler.

 Referring to Figures 1 to 3, there is illustrated a boiler incinerator according to the invention referenced as a whole 1, intended to incinerate waste in particular household consisting of combustible materials such as paper, cardboard and plant materials.

 The boiler-incinerator comprises a hearth 2 in its lower part, an exchanger 4 in the central part, a chimney 6 in its upper part and a grate 3 for receiving the waste in the hearth.

 The hearth 2 includes a grid 3 which can be slightly inclined relative to the horizontal to receive the waste. When it is paper or cardboard, the waste is advantageously placed in the waste introduction system 8 comprising an airlock 10 and a hatch 12, then shredded by the crusher 14 and finally introduced into the hearth 2 of the boiler by the feed screw 16. The other fuels such as wood, textiles or plants are introduced directly into the hearth by a first drawer 18. The airlock 10 makes it possible to store the waste so as to gradually introduce it into the hearth.

 The incinerator hearth has two zones on either side of the grid receiving combustible fluid. In the upstream zone 20, the combustion is carried out by excess of oxidizing fluid in order to obtain a more complete incineration of the waste, while in the downstream zone 22 the combustible fluid is injected to adjust the characteristics of the combustion and approach stoichiometric conditions. This re-burning operation has the effect of reducing the formation of polluting emissions based in particular on nitrogen oxides.

 On the other hand, during the ignition operation of the boiler, given the specific characteristics of each of these burners (21, 23), the one operating in excess of air will be lit first, located in the upstream area of the fireplace, then the one operating in the absence of air located in the downstream area.

 The exchanger 4 is constituted by a tube wound in a helix so as to favor the heat exchange between the products of combustion of the exchange zone which has a high temperature and the fluid to be heated circulating in the tube as indicated by arrows 24 and 26.

 The lower part of the hearth comprises an ash evacuation system constituted by a second drawer 28 with automatic opening with prohibition of starting the boiler in the event of opening.

 In Figures 2 and 3, we see two alternative embodiments of operating under vacuum or overpressure inside the boiler.

 Figure 2 shows a slightly pressurized system where a fan 32 is placed on the waste introduction system, the hatch 12 for putting them in this system is then placed laterally.

In this case the hatch 12 of the waste introduction system is magnetically locked.

 In FIG. 3, the system operating under vacuum with respect to the atmosphere is equipped with a mechanical vacuum cleaner 34, a flap 36 regulating the temperature of the combustion products and a direct ventilation flap 30 of the hearth provided at -above the ash pan and regulating the vacuum in the hearth regardless of the size of the waste introduction circuit.

Claims (9)

 1. Boiler-incinerator (1) of waste comprising in its lower part a hearth (2) into which fuel is introduced, and where is disposed a grid (3) receiving the waste to be incinerated, an exchanger (4) in the central part to heat a fluid circulating in the exchanger using combustion products from the hearth, a chimney (6) in its upper part for the evacuation of combustion products.  2. Boiler according to claim 1, characterized in that it comprises at least two burners (21, 23) for achieving staged combustion, the fuel being constituted by a combustible fluid supplying said burners in the presence of oxidizing fluid.  3. Boiler according to one of the preceding claims, characterized in that it comprises a system for introducing waste (8) into the hearth comprising:  - an entry airlock (10) for the storage of waste,  - Means for bringing (16) waste from the airlock to the hearth, these feeding means having a passage section smaller than that of the airlock, and isolating the airlock from combustion in the hearth.  4. Boiler according to claim 3, characterized in that the waste introduction system also comprises a crusher (14) placed between the airlock and the supply means (16).  5. Boiler according to claim 3 or 4, characterized in that the supply means (16) consist of a supply screw mounted tightly in the body in which it rotates.  6. Use of the boiler (1) according to one of the preceding claims in the residential setting for an individual or for a reduced community such as a building.  7. Operating method of a boiler-incinerator in which:  - at least one exchanger in which a fluid to be heated circulates is heated by combustion products generated by combustion at the location of at least one combustion zone,  - And waste is incinerated at the location of at least this combustion zone, the heat produced by this incineration completing the heating of said exchanger.  8. Method according to claim 7, characterized in that the combustion takes place in two stages between which the waste is placed:  - one upstream from the direction of propagation of the combustion products, where the conditions are particularly favorable for incineration,  - the other downstream, where the combustion products from the upstream stage are re-burned.  9. Method according to claim 8, characterized in that the combustion takes place in excess of oxidizing fluid relative to the fuel in the upstream stage, and in the absence of oxidizing fluid relative to the fuel in the downstream stage.