CN1344890A

CN1344890A - Venturi tube

Info

Publication number: CN1344890A
Application number: CN01111246A
Authority: CN
Inventors: 帕斯德里诺－乔治
Original assignee: Lialu S P A
Current assignee: Lialu S P A
Priority date: 2000-03-03
Filing date: 2001-03-05
Publication date: 2002-04-17
Also published as: EP1130319B1; ES2240007T3; DE60020517T2; EP1130319A1; ATE296994T1; DE60020517D1

Abstract

In order to improve the performance of the flue gases exhaust from the tight chamber boiler, IABER limited liability company uses a hooked pressure tube and a venturi tube, mounted inside the scroll. The location of the venturi and pressure tubes within the fan scroll allow pressure detectors not be affected by the intake air flow, caused by the natural draught of the stack, when the boiler is off. Also the venturi tube alone is useful to this purpose; actually, the solution providing for the only presence of the venturi tube allows a higher stability of the pressure signal reaching the pressure switch and assures that the boiler is shut-off in case of abnormal machine operation.

Description

Venturi tube

The objective of the invention is to improve the performance of closed chamber type boiler, make it pass through the required test of prEN483 standard of constructing about C5.

About the prEN483 standard.The prEN483 standard has covered C type (closed type) boiler that is equipped with the atmospheric combustion device, and its thermal power rating is equal to or less than 70Kw.

This standard code be designed for the requirement and the method for testing of reasonable use, classification and sign aspect of structure, security, performance, the energy of the gas fired-boiler of central authorities heating.

Construct about C5.The C5 structure is the such system that is limited by the prEN483 standard, that is, wherein C type (closed type) boiler is connected in two terminal units by independent pipeline, and these two unit lay respectively in the zone with different pressures.In the practice, following two kinds of situations will take place:

One is air-breathing on a wall, and exhaust (referring to Fig. 1) on another relative wall

One is air-breathing by wall, and by the top exhaust.

PrEN483 points out that the smoke discharge pipe of An Zhuaning should be endowed 2 millibars vacuum according to this configuration; Under these conditions, machine should be lighted frequently, and it is stable that flame should keep.

As-Is is that the IABER boiler can not pass through this test.Force pipe and Venturi tube are installed in fan connector inside (referring to Fig. 2).

This force pipe can be read static pressure, and Venturi tube can be read vacuum tightness, and its reading is along with the variation of air velocity by it changes.

These two members are connected in one can measure pressure switch that any pressure changes (referring to Fig. 3 a).

This pressure switch is an electromechanical assembly, its position of " opening " 100+/-6Pa, and the position of " pass " 72+/-5Pa.

When boiler startup, for security reasons, the software of control boiler attendance is checked the position of pressure switch.Have only when pressure switch is in the position of " pass ", just agree boiler startup.

Under the test condition of C5 structure, 2 millibars the vacuum that puts on smoke discharge pipe can produce an airflow that causes the boiler internal pressure to change, thereby makes pressure switch turn to " opening " position.Therefore, software can not agreed boiler startup.

Fig. 1 is the synoptic diagram of C type boiler;

Fig. 2 a is the synoptic diagram of basic scheme of the present invention;

Fig. 2 b is another synoptic diagram;

Fig. 3 a is the synoptic diagram of pressure switch;

Fig. 3 b is the synoptic diagram of differential pressure switch;

Fig. 4 is the synoptic diagram of Venturi tube;

Fig. 5 is the synoptic diagram of force pipe;

Fig. 6 is the synoptic diagram of force pipe installation site;

The various details scheme.The FIME fan type GR00680P device that is used for alkaline boiler has been installed Venturi tube (referring to Fig. 4) and hook-type force pipe (referring to Fig. 5) in volute.

Venturi tube can be read a force value, and this force value is lower than the static pressure in the volute, and is directly proportional with combustion gas speed on this aspect.

The selection (referring to Fig. 6) of force pipe position has been become the factor of most critical.But actual measured value is read by the pressure switch that a detected pressures changes.The reading of this pressure switch should be stable under normal operational circumstances, should reduce under the operational circumstances of abnormality, switches to " pass " to guarantee boiler.Whether signal can correctly reduce depends on Venturi tube and the position of hook-type force pipe in fan volute.Therefore, the position of two pressure detectors is very important, needs could determine through test of long duration.

Venturi tube and the hook-type pipe position (as shown in Figure 6) in fan volute can be guaranteed by C5 test (according to prEN 483/1998 standard), this is because these two pressure detectors can not close the stopping time at boiler and be subjected to influence because of the air inlet flow that natural suction caused of chimney.

With in the pipe of combustion gas connector, compare, done significant advantage like this.In fact, in the case,, should read a vacuum values, thereby it is difficult to by test in the Venturi tube at fluid network center if apply a suction force (for example will test required suction force) by C5.On the contrary,, just can make it exempt from the influence that sucks airflow if Venturi tube is arranged in the fan volute, thus can be by test.

Therefore, Venturi tube should be very inresponsive to the fluid that the simulation boiler pass suction force that the stopping time produced (test C5) is forced, but the velocity variations in the time of should be to fan work in the fluid network is extremely sensitive, so just can break down or gas emission pipe accident when closing, boiler is automatically closed down at fan.

In fact, the test of being carried out shows that before boiler was closed down owing to the effect of pressure switch, the concentration of emanation kept below 2000ppm CO, and is lower than 1000ppm CO when restarting, and meets the requirement of prEN483/1998.Except above-mentioned advantage, this scheme can also be saved cost greatly.

This standard code be designed for the requirement and the method for testing of reasonable use, classification and sign aspect of structure, security, performance, the energy of the gas fired-boiler that central authorities heat.

Construct about C5.The C5 structure is a system that is limited by the prEN483 standard, and wherein C type (closed type) boiler is connected in two terminal units by independent pipeline, and these two unit are positioned at the zone with different pressures.In the practice, following two kinds of situations will take place:

-air-breathing on a wall, and go up with different pressures exhaust (referring to Fig. 1) at another wall (not being at that relative wall)

-air-breathing by wall, and by the top exhaust.

PrEN483 points out that the flue gas of the boiler of An Zhuaning should be endowed 2 millibars vacuum according to this configuration; In the case, machine should be lighted frequently, and it is stable that flame should keep.

Force pipe can be read vacuum values, and this reading is along with the variation of the air velocity by force pipe changes.

When boiler startup, for security reasons, the software of control boiler attendance is checked the position of pressure switch.Have only when pressure switch during, just agree boiler startup for the position of " pass ".

Under the test condition of C5 structure, 2 millibars the vacuum that puts on the gas emission pipe can produce an airflow that causes the boiler internal pressure to change, thereby makes pressure switch turn to " opening " position.Therefore, software can not agreed boiler startup.

The FIME fan type GR00680P device that is used for alkaline boiler is installed in (referring to Figure 4 and 5) in the volute with Venturi tube.

Venturi tube can read at that point one pressure of inspiration(Pi) value that is directly proportional with velocity of flue gas; The vacuum signal of Chan Shenging can be detected by pressure switch like this.Therefore, it can " perception " change (PD) by two pressure that pressure signal produced that come from a Venturi tube and a static tube (referring to Fig. 3).

Under afore-mentioned, static tube constitutes (referring to Fig. 2) by a straight tube, gathers the signal that comes from smoke discharge pipe.Present static tube just is made up of the forward voltage diode of pressure switch, reads vacuum values in the boiler bellows (referring to Fig. 3 and the scheme that is used for alkaline boiler).

Can guarantee under worst condition (that is, pipe has maximum width, and works) that PD minimum in the course of work of boiler is 120Pa under the situation of peak power.

This PD value is to produce like this, that is, make Venturi tube be positioned at the position of volute, and the diameter of venturi groove be 4.6+/-0.1mm.

Owing to carried out these adjusting measures, Venturi tube can produce the vacuum signal of about 150Pa.

Under these conditions, but the second pressure transducer perception one of pressure switch is approximately the vacuum signal of 30Pa.

Therefore, be 120Pa (150Pa of Venturi tube-direct air-breathing 30Pa=120Pa) by the detected PD value of this pressure switch.

The advantage of this scheme mainly is reflected on the high stability of pressure signal.

Under normal operating conditions, the signal that arrives at pressure switch should be stable, but should reduce under the operating conditions of abnormality, thereby guarantees that boiler closes down.Signal can correctly reduce the normally result of venturi positive interaction.

In addition, the configuration (as shown in Figure 5) of Venturi tube in fan volute makes boiler can test (standard that meets prEN483/1998) by C5.In fact, Venturi tube can not closed the stopping time at boiler and is subjected to influence because of the air inlet flow that natural suction caused of chimney on this position.

So just constitute a significant advantage.In fact, in fan volute, Venturi tube is on the position that exempts from fluid influence, thereby can test (2 millibars vacuum draves) by C5.

Therefore, when boiler closes the stopping time (C5 test), Venturi tube should be unable to be sensitive to because of simulation and vacuumize the fluid of forcing, but when fan work, should be extremely sensitive in the velocity variations of fluid network, so just can break down or smoke discharge pipe accident when closing, boiler is automatically closed down at fan.

At IABER R﹠amp; The test that carry out in the D laboratory shows that before boiler was closed down owing to the effect of pressure switch, the concentration of emanation kept below 2000ppm CO, and is lower than 1000ppmCO when restarting, and meets the requirement of prEN483/1998.

Claims

1. a method is characterized in that, the reposition of force pipe.

2. the method for claim 1 is characterized in that, the reposition of hook-type pipe.

3. the method for claim 1 is characterized in that, new revised restarting.

4. the method for claim 1 is characterized in that, the new di of venturi groove.

5. the method for claim 1 is characterized in that, one second sensor occurred.