DE3211018A1 - Automatic draught regulating device for solid-fuel boiler - Google Patents

Abstract

In a regulating circuit for automatic draught regulation, a thermal firing regulator is used as control member. The firing regulator is, however, not adjusted by hand, but by a motor which receives its actuating signals from a control. The control detects, via temperature sensors, boiler forward run temperature, external temperature and flue gas temperature and, via a resistance value, the adjustment of the handwheel. The overall control is divided into a control part, which essentially ensures an adjustment of the handwheel dependent on the external temperature, and an auxiliary regulator which, by corresponding design of its electronics, ensures that the air flap has a constantly small degree of opening during the heating phase and that the air flap closes completely when the fire is going out. By the electronic air-flap control, an optimally energy-saving and uniform permanent combustion is achieved, which ensures a high degree of efficiency of an installation regulated in such a manner. Further advantages of such regulation are the easy mountability and retrofittability and safety against overheating by the firing regulator.

Description

DESCRIPTION

Automatic 7 ug control device for solid fuel boilers The invention concerns an automatic draft control of a solid fuel boiler with inclusion the effect of a thermal combustion controller with additional evaluation of the flue gas temperature for setting the opening angle of an air or combustion flap. The setting the combustion controller is also dependent on the outside temperature.

The control of the heating output of solid fuel boilers is already technically resolved in different ways and distances.

If you look at the possibility of changing the amount of fuel supplied As in the case of shaking grate systems, for example, the performance is usually through Regulation of the air supply controlled.

In this context, methods are known in which the air pressure in the combustion chamber is the input variable of a control loop, the manipulated variable of which is the speed of a fan motor continuously changed. (D 28 33 463) With others Method (D 27 18 520) is the speed of a fan motor as a function of the Oxygen and / or CO2 content of the exhaust gas is continuously regulated.

Furthermore, a control is known in which the gas pressure is also known serves as a measured variable in the combustion chamber. It is compared to atmospheric pressure and controls a motor via appropriate electronic devices regulates the degree of opening of the air flap.

Other regulations that primer the pressure difference between the combustion chamber and the environment to control the air flap make the degree of opening of the Air flap in addition to the heat requirement of the heating system and / or the oxygen concentration in supply air or exhaust gas dependent. (Japan No.

Sho 53 - 01451718) There is also a known regulation that depends on from the minimum value of the exhaust gas temperature by means of corresponding electrical signals controls a variable speed motor. for this purpose an NTC thermistor is arranged in the exhaust duct, which is included in a bridge circuit. This regulation is however for oil boilers designed. (DE 24 21 873 from Dannfoss) The Buderus company controls an induced draft regulator for solid fuel boilers as a function of the boiler load resulting from the flow rate and temperature difference between boiler flow and boiler return. (DE 30 25 966) In the case of oil boilers, according to DE 29 50 689, the value of the smoke gas or soot density is used as regulating measured variable used to control the supply air volume.

In DE 2757 843 a valve in the flue gas exhaust pipe is a function opened continuously to the temperature detected by a sensor in the flue gas duct or closed.

In another automatic draft regulation on a heater core for solid fuel is a temperature sensor that in the heat radiation range of the exhaust pipe is arranged, remainder of a circuit arrangement which has a Control circuit switching signals for an electromagnet that generates the degree of opening a combustion flap controls. (DE 29 09 539) For a long time already thermostatic combustion controller known. (Samson company, Frankfurt; Krona company) These Regulators work on the principle of liquid expansion, steam expansion or similar principles. The expansion caused by the warming is over Lever devices or the like in a sufficiently large control path for the air or combustion flap implemented.

An improved form of this type of combustion controller is through suitable mechanics, which are thermostatically controlled, if the value falls below this limit the temperature set on the handwheel by a larger amount the air or Firing flap closed. This prevents cooling losses to a considerable extent via the flue gas duct when the fire goes out.

Many of the above options are due to their design only with a disproportionate amount of effort, sometimes not at all afterwards mountable. Other solutions only cover part of the energy saving Solution necessary readings.

It is now the object of the invention to regulate the output of a heating boiler to create for solid fuels of the type mentioned at the beginning in which the said Disadvantages are avoided.

According to the invention, the object is achieved in that a control device with corresponding temperature sensors on an actuator, that is from a motor Setting of the handwheel is operated, so that this setting in Essential is a function of the outside temperature. In addition, the flue gas and flow temperature of the boiler is detected and converted into control signals by appropriate electronic circuits implemented for the rotor, so that in the heating-up phase energy losses due to excessive Flue gas temperatures are avoided and the boiler cools down in the cooling phase is slowed down. Thanks to the electronic air flap control depending on the Measured temperatures, a metered air supply is then achieved that a optimal and energy-saving combustion is guaranteed.

The following is a suggested implementation for the connection of thermal combustion controller as an actuator and the actuating motor (Claim 1). Description and numbers refer to Figure 1 of the drawings.

A gear 1 with a centric-cylindrical opening that of the shape of the handwheel of a combustion controller 3 is adapted is attached to the handwheel 2 and, if necessary, securely fastened by a screw 4. The speed of a motor 5 becomes through a gear 6 firmly connected to the rotor to five to ten revolutions reduced per minute on gear 7. The engine and the associated gearbox are attached to two retaining brackets 8 (one behind the other in FIG. 1). The retaining bracket are welded to one-half of a clamp 9. With two screws 10 is the clamp attached to the combustion controller in the manner shown.

Via the gear 7, gear 1 and thereby the handwheel in turn can now 2 are operated. The air or combustion flap is then activated in a known manner a lever rod 11 is confirmed by a chain not shown in FIG.

There are limit switches at a suitable point for safety reasons to be provided.

The following is an exemplary embodiment for the control-related Structure of the automatic draft control device with reference to FIG. 2 in more detail to be explained.

The overall task of the regulation is basically divided into four Sub-tasks: 1. The outside temperature-dependent setting of the handwheel on the combustion controller (possibly with a restriction to a minimum of 60 ° C for wood burning).

2. In the heating-up phase, the temperature should be set on the handwheel 10 to 15 ° C above the boiler flow temperature.

3. If the flow temperature falls below 15 to 20 oC the required value, depending on the outside temperature, the combustion flap should close completely.

4. If the smoke temperature is higher than 250 to 300 0C (adjustable depending on the type of boiler), the air damper should be fully open for a short time or partially close.

Regarding point 1: The value of one of the outside temperature sensors in the form of a thermistor 1, the reference variable w of a controller S is its manipulated variable ys forms the reference variable w 'of an auxiliary controller HR. The auxiliary regulator becomes then depending on the type of manipulated variable ys of the control S (signal "close" or signal "open")) affects the motor of the control element. (See also point 2) Regarding point 2: The task of this part of the control is to prevent during the heating-up phase the air flap too far is open and amit due to excessive air supply Significant energy losses to the incineration process due to excessive flue gas temperatures develop.

rend the entire hoof heater, d. H. until the flow temperature setting is reached on the handwheel which is required due to the outside temperature (see section 1) the control S sends an "open" signal (manipulated variable ys).

However, this does not affect the rotor, but is a reference variable w 'of the auxiliary controller HR. During this time, the auxiliary controller constantly compares the operating variable x (boiler flow temperature) and auxiliary command variable w ''. This auxiliary guide is connected to the actuator and therefore proportional to this variable Photentiometer generated. Depending on these values, the auxiliary controller generates a Control signal y for the motor, so that the setting of the handwheel cd. 1 (3 to 15 OC (adjustable) is above the boiler flow temperature.

as a result, the air flap is even during the entire heating-up time Depending on the setting, one to two centimeters open, which means an optimal air supply is achieved.

Regarding point 3: If no signal ys is given by the controller S, compare the auxiliary controller HR auxiliary command variable w '' (resistance value depending on the handwheel setting see also point 2) and operating variable x (boiler flow temperature). Will the farm size x by more than 15 to 20 0C (adjustable) smaller than the auxiliary command variable w "so the air kiaone is closed. At the same time, a signal (optical or acoustically) the closing of the air duct due to lack of fuel is indicated.

Throws through an elector mechanical or electronic circuit It also ensures that the air flap will only be activated again when the boiler temperature rises opens.

Regarding point 4: A thermal element Th constantly determines the flue gas temperature recorded. If the temperature rises above a value of 250 to 300 ° C (adjustable for each depending on the design of the boiler), a threshold value switch @ 1-ter 3 turns it into the auxiliary controller A signal is generated for the motor, so that the air flap briefly wholly or partially closes. After the flue gas temperature has fallen below the set value, it is activated the flap is regulated again according to point 2 or 3.

As an additional facility, the adjustment of the handwheel is via the motor can also be operated manually. This is done by a potentiometer 2 which then instead of the thermistor it becomes the reference variable w of the control system.

It would also be conceivable that the heating pump after closing the air flap is switched off according to point 3.

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Claims (8)

P A T E N T A N S P RÜ C H E 1. Device for energy-saving automatic draft regulation for stoves or firing boilers for solid fuels characterized in that the actuator of a control system is a thermal Combustion controller is and a geared motor is attached to it and / or is screwed or connected in any other suitable manner, so that the rotor adjusts the opening angle by turning the handwheel of the combustion controller the air or combustion flap. 2. Device according to claim 1, characterized by a sensing device, preferably a thermistor, which is suitable for the weather conditions (temperature, wind, sun) is subject to and part of a circuit arrangement that the actuator off Claim 1 affects such that the opening angle of the air or combustion flap from claim 1 is essentially a function of the above-mentioned measured value. 3. Device according to Ansnruch 1, characterized by one with the Actuator directly connected and therefore proportional to this variable potentiometer. 4. Apparatus according to claim 1, characterized by a further Temperature sensor, preferably an NTC thermistor, which records the Ressel flow temperature serves. 5. Apparatus according to claim 1, characterized by an auxiliary control device HR, which records the values according to claims 2 to 4, compares them and uses them accordingly Signals to the rotor a constant, optimal opening angle of the primary air flap guaranteed during the heating-up phase. 6, device according to claim 5, characterized in that the auxiliary control device HR detects the values according to claims 3 and 4 after the end of the heating-up phase, compares them and when the boiler flow temperature decreases by an adjustable amount, the air or the combustion flap closes with priority. 7. Device according to Ansnruch 5, characterized in that according to the Closing the air or furnace chamber on the basis of the conditions according to claim 6 this is indicated by a signal. 8. Device according to claims 1 and 5, characterized by a further Sensing device, preferably a thermocouple, those in the smoke exhaust pipe is subject to the prevailing temperature, as well as an associated threshold switch, which ensures that at a certain, adjustable temperature, the fire will open The flap closes partially or completely for a short time.