DE60032725T2 - Control system for boiler - Google Patents

Abstract

The system for the combined adjustment of air and gas, for the control of combustion and for an optimum efficiency at variable thermal loads in gas-fired boilers, can be used on a wide range of boilers. At the starting of the boiler, a control and adaptation cycle of the fan system, air sensor and flue-gas exhaust is carried out; if these tests give satisfactory results, the machine is started. The system offers two different types of control: simplified and complete. <IMAGE>

Description

The System for the combined regulation of air and gas to control combustion and to achieve optimized variable thermal performance Loads in gas fired boilers can, thanks to some simplifications across from usual Systems used in many boilers. A combined air / gas regulation system according to the preamble of claim 1 is known from the document EP-A-0909922 known.

1. Description

a) Complete control

• – Sensor zum Erfassen einer Wassertemperatur S1 (40);
• – ein Potentiometer zum Einstellen der erforderlichen Temperatur P1 (PTS Sanitär-Temperatur, PTR Umgebungserwärmung);
• – ein Gebläse (FA1) (36), dessen Geschwindigkeiten durch das mP-basierte Steuerpult gesteuert wird;
• – ein Differenz-Analog-Druckschalter (P.A.D.) (39) zum Steuern des Vakuums in der Verbrennungskammer;
• – Ein Gasmodulator (MOD.) (41), der durch das mP-basierte Steuerpult gesteuert wird; und
• – ein Sicherheitsthermostat, das an dem Kessel angeordnet ist.

The main components of this controller ( 1 ) are the following:

• Sensor for detecting a water temperature S1 ( 40 );
• - a potentiometer for setting the required temperature P1 (PTS plumbing temperature, PTR ambient heating);
• A blower (FA1) ( 36 ) whose speeds are controlled by the mP-based controller;
• - a differential analogue pressure switch (PAD) ( 39 ) for controlling the vacuum in the combustion chamber;
• A gas modulator (MOD.) ( 41 ) controlled by the mP-based controller; and
• - A safety thermostat, which is located on the boiler.

At the Start of the boiler is a control and adaptation cycle of the blower system, performed the air sensor and the exhaust gas.

• – Der Signalwert, der durch den P.A.D. erzeugt wird, wird überprüft. Ein solches Signal sollte einen festen Wert nicht überschreiten. Diese Operation stellt sicher, dass keine Upwind-Erscheinung (upwind) oder möglicher Fehler in dem Sensor/Elektroniksystem vorliegt.
• – Wenn die zuvor beschriebene Überprüfung zufriedenstellend ist, wird das Gebläse gestartet. Das P.A.D.-Signal sollte größer als der zuvor genannte Wert plus einer vorgegebenen Konstante sein, um sicherzustellen, dass ein ordnungsgemäßes Vakuum in den Brennkammern vorliegt und die Adaption der Gebläsegeschwindigkeit an das Abgassystem ordnungsgemäß erfolgt ist.
• – Sollte auch diese Überprüfung zufriedenstellende Ergebnisse liefern, wird der Brenner gestartet.
• – Während der Operation wird der Druck in der Brennkammer kontinuierlich überwacht. Wenn der Vakuumwert unter einer vorbestimmten Grenze fällt, wird der Brenner abgeschaltet.

The operations performed are the following:

• - The signal value generated by the PAD is checked. Such a signal should not exceed a fixed value. This operation ensures that there is no upwind or potential error in the sensor / electronics system.
• - If the above check is satisfactory, the blower starts. The PAD signal should be greater than the aforementioned value plus a predetermined constant to ensure that proper vacuum is present in the combustion chambers and that the fan speed adaptation to the exhaust system has occurred properly.
• - Should this check give satisfactory results, the burner will start.
• - During the operation, the pressure in the combustion chamber is continuously monitored. If the vacuum level falls below a predetermined limit, the burner is shut down.

According to the wiring diagram in 2 the required temperature is selected by means of a potentiometer P1 and compared in the circuit PIDA with the temperature detected by the sensor S1. The fan speed is calculated as a function of the difference between these values to achieve the required capacity. The fan speed is controlled by means of a PIDB regulation system to ensure the required speed stability, using as feedback signal the vacuum present in the combustion chamber detected by the analog pressure switch PAD.

When a function of this vacuum, the controller generates the current one Value to be sent to the modulator, so that a constant and optimal air-gas ratio is achieved. This will ensure that the combustion with emission levels within the required limits, while optimum efficiency is maintained at every thermal load.

The Placing a thermostat on the burner ensures that the Boiler always within the required emission limits and safe is operated. As a function of its temperature, the burner can in the case of an abnormal rise in temperature due to a fault even stop the flame in the air or gas control system.

One such thermostat is electrically connected in series with respect to already existing limit thermostat arranged. An intervention of this Thermostats convict the Boiler then into a state of non-volatile shutdown.

2 also shows the block ACF, which checks the presence of the flame and ensures the safety functions by acting on the gas valve actuators.

3 shows the functional diagram of such a system.

In represents this diagram T (PTS) the value for a required sanitary temperature (or Ambient heating temperature) which is determined by means of the potentiometer P1. T (SS) represents the value of the water temperature detected by the sensor S1. These values are compared in the sum block A1, and the result the error e (T) is supplied to a control system PID which through the blocks Kp e (T), Ki Int [e (T)], Kd d [e (T)] e A2 is represented by the value V (N) to obtain the value of the required vacuum in the Combustion chamber represents the thermal load.

This value is in the sum block A4 with the feedback value Vc (H) produced by the PAD and the value of the actual vacuum generated by the blower. The result, the error e (H), is supplied to a control system PID represented by the blocks Kp e (H), Ki Int [e (T)], Kd d [e (T)] dt and one block V (F) = f [e (H)] to obtain VF representing the required blower speed required for the blower to generate the required vacuum in the combustion chamber.

Of the Return Value Vc (H) generated by the P.A.D. is also produced is used as the input of the block T, the I (mod), the Modulatorstromwert, according to a generated predetermined curve that correlates with Vc (mod) to I (mod), about the relationship of air (generated by the blower at a speed VF) and gas (he testifies through the modulator with a current I (mod)) and optimum combustion ensure while a uniform thermal Efficiency is maintained under varying loading conditions. The current the value I (mod) supplied to the modulator of the gas valve, generates the actual pressure P (gas) in the combustion chamber.

in the Trap of overheating burner due to poor combustion with non-standard emissions the burner thermostat (THERM BURN) is switched on, which causes the Burner is turned off, so that the boiler safely shut off becomes.

b) Simplified control

• – Ein Sensor zum Erfassen einer Wassertemperatur S1 (40);
• – ein Potentiometer zum Einstellen der erforderlichen Temperatur P1 (PTS Sanitär-Temperatur, PTR Umgebungserwärmung);
• – ein Gebläse (FA1) (36), dessen Geschwindigkeit durch das mP-basierte Steuerpult gesteuert wird;
• – ein Minimum-Differenz-Druckschalter (PD.) (39) zum Steuern des Vakuums in der Verbrennungskammer;
• – ein Gasmodulator (MOD.) (41), der durch das mP-basierte Steuerpult gesteuert wird; und
• – ein Sicherheitsthermostat, das an dem Brenner angeordnet ist.

The main components of this control, as in 4 are shown are:

• A sensor for detecting a water temperature S1 ( 40 );
• - a potentiometer for setting the required temperature P1 (PTS plumbing temperature, PTR ambient heating);
• A blower (FA1) ( 36 ) whose speed is controlled by the mP-based controller;
• A minimum difference pressure switch (PD.) ( 39 ) for controlling the vacuum in the combustion chamber;
• A gas modulator (MOD.) ( 41 ) controlled by the mP-based controller; and
• - A safety thermostat, which is located on the burner.

According to the in 5 The circuit diagram shown, the required temperature is selected by means of a potentiometer P1 and compared in the circuit PID of the character A with the detected by the sensor S1 temperature. The fan speed is calculated as a function of the difference between these values to achieve a constant air to gas ratio and to ensure that combustion with emission levels is within the required limits while maintaining optimum efficiency at each thermal load.

at every start of the boiler, a control cycle of the blower system, performed the air sensor and the exhaust gas.

Of the Value of the by the P.D. generated signal is checked. Such a signal should his consent not in the absence of the blower operation give; so there is no upwind appearance or possible Error in the pressure switch / electronics system.

at heat demand becomes the fan started at maximum speed to connect the differential pressure switch to ensure that the proper operation of the Blower / exhaust system to check.

During the Operation, the negative pressure in the pressure chamber is continuously monitored. When the vacuum level drops below a predetermined limit, there is the pressure switch P.D. no longer his approval, so that the boiler is switched off.

The Add a thermostat to the burner ensures that the boiler always within the required emission limits and with complete safety is operated. As a function of its temperature, the burner can in the case of an abnormal temperature rise due to a fault of the air or gas control system stop the flame.

One Such thermostat is in relation to the already existing limit thermostat electrically connected in series. An intervention of this thermostat converts the Boiler therefore in a state of non-volatile shutdown.

5 also shows the block ACF, which checks the presence of the flame and ensures the safety functions by acting on the gas valve actuators.

6 shows the functional diagram of such a system.

In this diagram, T (PTS) represents the value of the required sanitary temperature (or ambient heating temperature) detected by the potentiometer P1. T (SS) represents the water temperature value detected by the sensor S1. These values are compared in the sum block A1, and the result, the error e (T), is fed to a control system PID to obtain the value V (FAN) which is the value of the Ge blowing speed as a function of the demand of the thermal load.

This Value (V (fan)) corresponding to the blower (block V (F) = f [e (H)]) will generate the actual Speed VF.

Of the Value V (fan) is also used as the input of the block T, which is I (mod), the Modulatorstromwert, according to a predetermined curve, which correlates with V (fan) to I (mod) generates, around the air-gas ratio, which is generated by the modulator with the current I (mod) to maintain and to ensure optimal combustion while maintaining a constant thermal Efficiency is maintained under varying load conditions. Of the Current value I (mod), which is supplied to the gas valve modulator generated the actual Pressure P (gas) in the combustion chamber.

Claims (1)

A boiler air / gas control system comprising: a combustor having a burner (BURNER); a sensor ( 40 , S1) for detecting water temperature; a potentiometer (P1) for setting a required temperature; a blower ( 36 , FAN) whose speed is controlled by a microprocessor based control panel; a differential analog pressure switch (PAD) providing a signal correlating with the negative pressure in the combustion chamber; a gas modulator ( 41 , MOD) controlled by the microprocessor-based control panel; a first control device (PIDA, PIDB, PIDA) for controlling the speed of the fan ( 36 FAN) based on the negative pressure signal, the first controller (PIDA, PIDB; PIDA) including: a first PID controller (PIDA) for calculating a required fan speed as a function of a difference between the required one selected by the potentiometer (P1) Temperature and the water temperature detected by the sensor (S1); a second PID control unit (PIDB) for controlling the fan speed as a function of the required fan speed and the vacuum signal; a second controller (AIR / GAS RATIO) which generates a current as a function of the signal to control the gas modulator to achieve a constant and optimum air-to-gas ratio, characterized by comprising: a first one Activation device configured to selectively start the fan ( 36 FAN) on the condition that the negative pressure signal is below a predetermined value before the fan is started, selectively activating the burner (BURNER) on the condition that the signal is above the set value plus a predetermined constant after starting the burner Blower ( 36 , FAN) and that deactivates the burner (BURNER) when, in use, a vacuum level falls below a predetermined limit; a thermostat (BURN THERM) located on the burner and a second activation device (BURN THERM SAFETY CONTROL; SAFETY CONTROL) coupled to the thermostat (BORN THERM) and the burner (BURNER) to connect the burner (BURNER ) to be selectively activated based on the temperature measurement of the thermostat (BURN THERM); and another limit thermostat arranged in series with the thermostat (BORN THERM) of the safety device.