CN110657578A - Submerged combustion safety control system based on combustion chamber pressure protection - Google Patents

Abstract

The present invention provides an immersion combustion safety control system based on combustion chamber pressure protection, comprising a combustion controller, a gas pressure sensor, an air pressure sensor, a solenoid valve, a flame monitor, a combustion chamber, a smoke pipe, and a water bath, wherein the combustion Both the chamber and the heat exchanger are immersed in the water bath, and the high-temperature flue gas generated by combustion is blown out through the bubbling tube immersed in the water bath of the water bath, and exchanges heat and mass with the water bath, and the water bath exchanges heat with the heat exchanger. Heating the natural gas flowing through the heat exchanger, if the water level depth of the water bath decreases, the pressure of the combustion chamber will decrease, resulting in a change in the ratio of air and gas entering the combustion chamber. Therefore, the air-fuel ratio can be affected by the depth of the water level. When the time limit is set, the air-fuel ratio is greater than the lower limit of the explosion concentration of the gas, and the combustion is terminated to achieve the purpose of safety control.

Description

A safety control system for submerged combustion based on combustion chamber pressure protection

technical field

The invention relates to the technical field of new energy, in particular to an immersion combustion safety control system based on combustion chamber pressure protection.

Background technique

The submerged combustion heating device has high thermal efficiency and compact structure, which is very suitable for liquid heating. For example, liquefied natural gas (LNG) gasification using water bath heating, natural gas heating for antifreeze in stations, etc. In the submerged combustion natural gas heating device, the natural gas heat exchange tube is placed in a water bath, the high temperature flue gas of combustion is directly injected into the water, and the heat is transferred to the natural gas heat exchange tube through the water bath, which can achieve efficient heat exchange. However, natural gas is flammable and explosive, and the method of combustion heating in natural gas stations must be safe and reliable. The submerged combustion water bath is the guarantee of low temperature flue gas (below 100 ℃) emission. If the water bath drops rapidly due to natural gas leakage, especially high-pressure natural gas leakage, the high temperature flue gas may come into contact with the leaked natural gas. Therefore, if the water level drops abnormally, the burner needs to stop working.

At present, the commonly adopted measure is a flame-out control system based on flame sensing. When the flame is extinguished, the gas supply is cut off through an electrical signal sent by the flame sensor, thereby preventing gas leakage. However, the system only cuts off the gas after the flame is extinguished, there is no guarantee that the flame will be extinguished after the water bath is lowered.

SUMMARY OF THE INVENTION

The invention provides a immersion combustion safety control system based on the pressure protection of the combustion chamber, and the specific technical scheme is as follows:

It includes a sensor unit, an air intake unit, a combustion unit, a water bath unit and a heat exchange unit, wherein the sensor unit includes a combustion controller, an air pressure sensor, a gas pressure sensor, a solenoid valve and a flame monitor; the air intake unit includes an air nozzle, Gas nozzle, blower;

The air pressure sensor is arranged at the air outlet of the blower, the solenoid valve is arranged at the gas inlet of the gas injection hole, the gas pressure sensor is arranged at the gas inlet of the gas injection hole and is electrically connected with the solenoid valve, and the flame detector is arranged at the air inlet. The air inlet of the nozzle hole is electrically connected with the solenoid valve, the solenoid valve is arranged at the gas inlet end, and the combustion controller is respectively electrically connected with the air pressure sensor, the gas pressure sensor, the solenoid valve and the flame monitor;

The air nozzle holes and the gas nozzle holes of the air inlet unit are connected with the combustion unit, and the combustion unit and the heat exchange unit are respectively immersed in the water bath unit;

Further, the combustion unit includes a combustion chamber, a smoke pipe and a flue gas nozzle, and both the air outlet of the air nozzle and the gas outlet of the gas nozzle extend into the combustion chamber;

Further, the water bath unit is a water bath box, and a chimney is arranged on the upper part of the water bath box;

Further, the heat exchange unit is a heat exchanger, and cold natural gas is introduced into the heat exchanger;

Further, the air-fuel ratio set by the combustion controller is β ₀ , the flame-out air-fuel ratio of the flame monitor is β′, and the combustion chamber pressure generated by the water level of the water bath during normal operation is Then the relationship between the flameout condition and the set condition parameters is shown in the following formula:

in,

β ₀ , β′ are the design volume air-fuel ratio and flameout air-fuel ratio, Pa;

为正常运行设定水浴水位所产生的燃烧室压力，Pa；

Combustion chamber pressure generated by setting the water level in the water bath for normal operation, Pa;

p _b ′ is the combustion chamber pressure generated by the minimum water bath water level set for safety protection, Pa;

p _g is the gas pressure, Pa;

p _a is the air pressure, Pa;

高2000Pa；Further, the air pressure p _a is higher than the combustion chamber pressure

High 2000Pa;

Further, the gas pressure p _g is 2000Pa higher than the air pressure p _a ;

Further, the volume air-fuel ratio of the combustion controller is β, and the specific formula is:

in,

p _g is the gas pressure, Pa;

p _a is the air pressure, Pa

p _b is the combustion chamber pressure generated by the water level of the water bath, Pa;

Further, in the formula of volume air-fuel ratio β,

in,

K _g is the resistance coefficient of the gas nozzle;

Ka is the resistance coefficient of the air nozzle _;

A _g is the area of the gas nozzle, m2;

A _a is the air nozzle area, m2;

Preferably, a water level sensor can also be provided in the water bath.

Both the combustion chamber and the heat exchanger of the present invention are immersed in a water bath, and the high-temperature flue gas generated by combustion is blown out through a bubbling tube immersed in the water bath of the water bath, and exchanges heat and mass with the water bath, and the water bath communicates with the heat exchanger. Carry out heat exchange and heat the natural gas flowing through the heat exchanger. If the water level depth of the water bath box decreases, the pressure of the combustion chamber decreases, resulting in a change in the ratio of air and gas entering the combustion chamber. Therefore, the air-fuel ratio can be affected by the depth of the water level. When the lower limit of the water level is reached, the air-fuel ratio is made larger than the lower limit of the explosion concentration of the gas, and the combustion is terminated to achieve the purpose of safety control.

Description of drawings

FIG. 1 is a schematic structural diagram of the immersion combustion safety control system based on the pressure protection of the combustion chamber of the present invention.

In the picture: 01-Combustion controller, 02-Air pressure sensor, 03-Gas pressure sensor, 04-Solenoid valve, 05-Flame monitor, 06-Air nozzle, 07-Gas nozzle, 08-Combustion chamber, 09 - water bath box, 10- flue pipe, 11- flue gas nozzle, 12- heat exchanger, 13- chimney, 14- blower.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

则熄火工况与设定工况参数的关系如公式(a)所示。As shown in Fig. 1, the immersion combustion safety control system based on combustion chamber pressure protection of the present invention includes a combustion controller (01), a gas pressure sensor (03), an air pressure sensor (02), a solenoid valve (04), a flame Monitor (05), combustion chamber (08), smoke pipe (10), water bath box (09), set the pressure of combustion chamber (08) when the water bath water level drops to the minimum value set by safety protection as p _b ′, At this time, the air-fuel ratio also increases beyond the flammable concentration range, that is, the flame-out air-fuel ratio β′ is reached, and the set design volume air-fuel ratio is β ₀ , and the combustion chamber pressure generated by the set water bath water level in normal operation is

Then the relationship between the flameout condition and the set condition parameters is shown in formula (a).

in,

β ₀ , β′—design volume air-fuel ratio, flameout air-fuel ratio, Pa;

- The pressure of the combustion chamber generated by the set water level of the water bath during normal operation, Pa;

p _b ′—combustion chamber pressure generated by the minimum water bath water level set by safety protection, Pa;

p _g —gas pressure, Pa;

p _a —air pressure, Pa.

通过设定燃气压力p_g和空气压力p_a，可使水浴箱(09)的水位下降到安全保护设定的最低水位时，燃烧室(08)所产生的压力下降至p_b′，空燃比增大至β′，火焰熄灭，达到安全保护的目的。According to formula (a), when the water level of the water bath is satisfied for normal operation, the resulting combustion chamber pressure is

By setting the gas pressure p _g and the air pressure p _a , when the water level of the water bath (09) drops to the minimum water level set by the safety protection, the pressure generated by the combustion chamber (08) drops to p _b ′, and the air-fuel ratio Increase to β′, the flame is extinguished, and the purpose of safety protection is achieved.

The working principle of the present invention is as follows: when the equipment is in normal operation, the combustion air enters the combustion chamber (08) through the air nozzle (06) through the blower (14), while the combustion gas passes through the gas nozzle (07) at a certain air supply pressure. ) into the combustion chamber (08), when setting the water level of the water bath (09), the combustion controller (01) according to the set air-fuel ratio β and the air pressure p _a value of the air pressure sensor (02), according to the formula ( The algorithm of b) calculates the required gas pressure p _g , and adjusts the solenoid valve (04) through the feedback signal of the gas pressure sensor (03) to achieve the set air-fuel ratio, and in the case of combustion, through the flame monitor (05) ) signal keeps the solenoid valve (04) open to maintain the gas supply, when the flame is extinguished, the combustion controller (01) can not get the signal from the flame monitor (05), it will direct the solenoid valve (04) to cut off the gas supply .

in,

β—volume air-fuel ratio;

p _b - the pressure of the combustion chamber produced by the water level of the water bath, Pa.

in,

K _g - the resistance coefficient of the gas nozzle;

K _a - the resistance coefficient of the air nozzle;

A _g - the area of the gas nozzle, m2;

A _a —Air nozzle area, m².

The flue gas generated in the combustion chamber (08) enters the water bath (09) through the flue gas nozzle (11) through the flue gas pipe (10) to heat the water, and the water reheats the cold natural gas flowing through the heat exchanger (12). The flue gas is cooled and discharged from the chimney (13) through a water bath (09).

When the water level of the water bath box (09) drops, the pressure _Pb of the combustion chamber (08) drops accordingly, and the air-fuel ratio β entering the combustion chamber (08) changes. When the combustion chamber pressure _Pb drops to a certain extent, the air-fuel ratio β exceeds the range of the combustible gas concentration, and the flame is extinguished. At this time, the flame monitor (05) cannot monitor the flame, and the solenoid valve (04) is then controlled to cut off the gas supply. To achieve the purpose of interrupting combustion and cutting off the gas supply for combustion.

则熄火工况与设定工况参数的关系如上述公式(a)所示。Set the pressure of the combustion chamber (08) when the water level of the water bath drops to the lowest value set by the safety protection as p _b ', and the air-fuel ratio also increases beyond the flammable concentration range, that is, the flame-out air-fuel ratio β' is reached, and the set air-fuel ratio is β ₀ , the pressure of the combustion chamber generated by the set water level of the water bath in normal operation is

Then the relationship between the flameout condition and the set condition parameters is shown in the above formula (a).

通过设定燃气压力p_g和空气压力p_a，可使水浴箱(09)的水位下降到安全保护设定的最低水位时，燃烧室(08)所产生的压力下降至p_b′，空燃比增大至β′，火焰熄灭，达到安全保护的目的。According to formula (a), when the water level of the water bath is satisfied for normal operation, the resulting combustion chamber pressure is

By setting the gas pressure p _g and the air pressure p _a , when the water level of the water bath (09) drops to the minimum water level set by the safety protection, the pressure generated by the combustion chamber (08) drops to p _b ′, and the air-fuel ratio Increase to β′, the flame is extinguished, and the purpose of safety protection is achieved.

Air pressure p _a is greater than the pressure of the combustion chamber (08) 2000Pa higher, the gas pressure p _g is 2000Pa higher than the air pressure p _a .

The flame monitor, gas shut-off valve and proportional control valve of the present invention are not limited to a specific form, as long as they can realize sensing and control functions.

In addition, in the system of the present invention, electronic and physical water level sensors can also be added to realize the signal sensing of water level changes.

Compared with the current fire extinguishing control system based only on flame sensing, the immersion combustion safety control system of the present invention can not only cut off the gas supply after the flame is extinguished, but also can ensure that the water bath is lowered to a certain level to terminate the combustion, which is a combination of combustion The dual sensing system of chamber pressure sensing and flame sensing works together, which can terminate the combustion and cut off the gas supply, which can prevent the high temperature flue gas from contacting the combustible gas in the environment and the explosion caused by the continuous combustion after the abnormal drop of the water level. .

The submerged combustion safety control system of the present invention only needs to determine the relationship between the gas pressure, air pressure and water level of the burner, and does not require additional sensing equipment or components. The valve can be realized without increasing the equipment cost.

The above are the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (10)

1. An immersion combustion safety control system based on combustion chamber pressure protection, characterized in that it comprises a sensor unit, an air intake unit, a combustion unit, a water bath unit and a heat exchange unit, wherein the sensor unit includes a combustion controller, an air a pressure sensor, a gas pressure sensor, a solenoid valve and a flame monitor; the air intake unit includes an air nozzle, a gas nozzle, and a blower; The air pressure sensor is arranged at the air outlet of the blower, the solenoid valve is arranged at the gas inlet of the gas injection hole, and the gas pressure sensor is arranged at the gas inlet of the gas injection hole and is connected to the gas inlet of the gas injection hole. The solenoid valve is electrically connected, the flame detector is arranged at the air inlet of the air injection hole and is electrically connected to the solenoid valve, the solenoid valve is arranged at the gas inlet end, and the combustion controller is respectively connected with the air pressure sensor, the gas pressure sensor, the solenoid valve and the flame monitor are electrically connected; The air injection holes and the gas injection holes of the air inlet unit are connected to the combustion unit, and the combustion unit and the heat exchange unit are respectively immersed in the water bath unit. 2 . The immersion combustion safety control system based on combustion chamber pressure protection according to claim 1 , wherein the combustion unit comprises a combustion chamber, a smoke pipe and a smoke injection hole, and an air outlet of the air injection hole is an air outlet. 3 . Both the gas outlet and the gas outlet of the gas injection hole extend into the combustion chamber. 3 . The immersion combustion safety control system based on combustion chamber pressure protection according to claim 2 , wherein the water bath unit is a water bath box, and a chimney is opened on the upper part of the water bath box. 4 . 4 . The submerged combustion safety control system based on combustion chamber pressure protection according to claim 1 , wherein the heat exchange unit is a heat exchanger, and cold natural gas is passed into the heat exchanger. 5 . 5. The immersion combustion safety control system based on combustion chamber pressure protection according to claim 3, wherein the air-fuel ratio set by the combustion controller is β ₀ , and the flame-out air-fuel ratio of the flame monitor is β ', the combustion chamber pressure generated by the water level of the water bath during normal operation is

Then the relationship between the flameout condition and the set condition parameters is shown in the following formula: in, β ₀ , β′ are the design volume air-fuel ratio and flameout air-fuel ratio, Pa; Combustion chamber pressure generated by setting the water level in the water bath for normal operation, Pa; p _b ′ is the combustion chamber pressure generated by the minimum water bath water level set for safety protection, Pa; p _g is the gas pressure, Pa; p _a is the air pressure, Pa. 6. The submerged combustion safety control system based on combustion chamber pressure protection according to claim 5, wherein the air pressure p _a is higher than the combustion chamber pressure

High 2000Pa. 7. The submerged combustion safety control system based on combustion chamber pressure protection according to claim 5, wherein the gas pressure p _g is 2000Pa higher than the air pressure p _a . 8. The submerged combustion safety control system based on combustion chamber pressure protection according to claim 1, wherein the volume air-fuel ratio of the combustion controller is β, and the specific formula is:

in, p _g is the gas pressure, Pa; p _a is the air pressure, Pa p _b is the combustion chamber pressure generated by the water level in the water bath, Pa. 9 . The immersion combustion safety control system based on combustion chamber pressure protection according to claim 8 , wherein, in the formula of the volume air-fuel ratio β,

in, K _g is the resistance coefficient of the gas nozzle; Ka is the resistance coefficient of the air nozzle _; A _g is the area of the gas nozzle, m2; A _a is the air nozzle area, m2. 10 . The immersion combustion safety control system based on combustion chamber pressure protection according to claim 3 , wherein a water level sensor can also be provided in the water bath. 11 .

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