JPH0867886A - Odorizing of town gas - Google Patents

Abstract

PURPOSE: To provide a method for odorizing a town gas capable of supplying efficient energy saving effects, by shortening an evaporation distance of a odorizing liquid more than a conventional method, not requiring lengthening of gas piping length of an odorizing part and eliminating fining of liquid drop of the odorizing liquid up to an unnecessary degree in operating odorizing liquid. CONSTITUTION: In a method for odorizing a town gas by adding an odorizing liquid to the town gas and evaporating it, an odorizing liquid adding part is equipped with an odorizing liquid atomizer and a gas flow rate measuring part is installed at the upper stream of the odorizing liquid adding part to provide the method for odorizing a town gas capable of controlling the degree of atomization of the odorizing liquid in a device for atomizing the odorizing liquid according to a gas flow rate measured by a measuring part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of odorizing fuel gas, that is, city gas, which is sent from a central supply source to various consumers such as various factories, thermal power plants, and households by pipes, and more specifically, When adding odorant to city gas and evaporating it to odorize the gas, the addition and evaporation can be controlled immediately and accurately, and effective energy saving is also possible. A method for odorizing city gas.

[0002]

2. Description of the Related Art Natural gas or other fuel gas sent from a central supply source to each consumer through a pipe passes through a pressure regulator, a gas meter, an on-off valve and other equipment installed in each pipe. , Burner burner, gas turbine or gas engine, gas stove, gas range, gas rice cooker,
It is sent to and consumed by various combustion appliances such as instant water heaters, bath kettles and gas stoves.

These fuel gases are rarely used continuously all the time, and are often used intermittently as needed and consumed, but they are used regardless of whether the gas is used or not. It is necessary to ensure that there is no leakage from pipes, appliances, and combustion equipment at all times to ensure safety, and it is necessary to pay sufficient attention to the safety of the danger of incomplete combustion in combustion equipment.

Incidentally, the gas leakage can occur not only from the pipes, joints, gas meters, valves, etc., but also from these various combustion appliances themselves.
For this reason, the presence or absence of gas flow is detected, and the flow rate is measured when it is flowing, so that the presence or absence of gas leakage is monitored. Although necessary repairs and management are performed to ensure safety, odorous substances such as mercaptans are added to the gas pipes as one of the methods to immediately recognize the gas leak and warn of the danger. However, there is also adopted a method of easily and immediately detecting the leak by smelling the gas.

FIG. 2 shows one embodiment of the above-mentioned odorizing method for conventional city gas and other fuel gases. In the figure, 1 is a gas pipe, and the arrow (→) is the direction of the gas flow in the pipe 1. Further, 2 is an odorant tank, 3 is an odorant conduit, 4 is an odorant pump provided on the way, and the odorant conduit 3 is connected to an odorant supply pipe 6 through a valve 5. There is. As shown in the figure, the end of the odorant supply pipe 6 is installed in the gas pipe 1 in the form of a nozzle, and the odorant is dropped in a droplet form by the nozzle 7. 8 is the droplet.

A gas flow meter 9 measures the flow rate of the fuel gas passing through the gas pipe 1, and the signal line 10
The odorant is added in an effective amount (that is, an amount necessary to effectively detect the leak at the time of gas leak) according to the flow rate value of the gas sent through. At this time, the odorant liquid whose pressure is increased by the odorant liquid pump 4 is dripped from the nozzle 7 at the tip of the odorant liquid supply pipe 6, and this dripping liquid droplet 8 has a particle size when the gas flow rate is small. (= Diameter) It is atomized to about 0.2 mm to 5 mm, and this is evaporated by heat input from the surrounding gas, and odor is added to the gas.

In this case, when the gas flow rate in the gas pipe 1 is small, the particle size of the dropped liquid droplet 8 is as large as about 5 mm, so that before the entire amount of the liquid droplet evaporates, it drops on the lower surface in the pipe. It drops to form a wet surface, and the odorant is evaporated from this wet surface (in this case, it is necessary to secure the wet area). On the other hand, when the gas flow rate in the gas pipe 1 is high, atomization of the dropped droplets 8 is promoted according to the degree of the flow rate, and the droplets have a particle size of several hundreds μm.

Further, the dripping droplet 8 is directed in the direction of the gas flow (→).
The terminal velocity in the vertical direction of the liquid droplet 8 becomes smaller as the diameter of the liquid droplet becomes smaller due to the gas resistance, and the time to reach the lower surface of the pipe 1 becomes longer accordingly.
The smaller the droplet diameter is, the shorter the time until the evaporation of the droplet is completed. For example, when the droplet diameter is about several 100 μm, the time required to complete the evaporation in the air flow and the piping Since the time to reach the lower surface is almost the same, the flight distance of the droplet in the gas fluid becomes long, and the distance required for the odorant liquid to evaporate, that is, the evaporation distance, depends on [the diameter of the gas pipe 1, etc. However, the pipe diameter is 20B (= 500mm)
In the case of], it will reach several tens of meters.

The odorizing liquid must be contained as a gas in the gas and must be vaporized and vaporized before it reaches the burner or other combustion equipment. If the distance required for the liquid to evaporate) becomes long as described above, the odorizing portion, that is, the pipe after the nozzle 7 must be made longer by that amount, which is essentially unnecessary for supplying gas. Not only the pipe length, but when installing this odorizing part in the front pipe of the above-mentioned various combustion appliances, it is necessary to install it further ahead including the evaporation flight distance, etc. It is extremely inconvenient and uneconomical.

3 (a) and 3 (b) are schematic views for explaining the above-mentioned various relationships in consideration of the relationship with the gas flow velocity. Of these, FIG. 3 (a) shows the gas. Flow velocity (V
₀ ) is large, and FIG. 3B is an explanatory diagram for the case where the gas flow velocity is small. First, in FIG. 3A, when the droplet of the odorizing liquid dropped from the nozzle 7 has a small diameter (indicated by dp ₁ in the figure), it evaporates at a flight distance of l ₁₁ as illustrated. However, if the diameter is large (indicated by dp ₂ in the figure), it follows the locus as shown and disappears at a flight distance l ₁₂ .

On the other hand, in the case of FIG. 3B, that is, when the gas flow velocity (V ₀ ) is small, the flight distance of the dropped liquid droplets becomes short. It can be large [dp _{2 in} Fig. 3 (b), flight distance:
l ₂₂ <l ₂₁ ], therefore, in this case, operating with the droplet size small (dp _{1 in the} figure) means adding unnecessary energy corresponding to the miniaturization.

At this time, the terminal velocity in the vertical direction (Vz) of the dropped liquid droplet, the evaporation time (t) of the liquid droplet, and the flight distance (l) until the evaporation of the liquid droplet are completed are as follows (1),
It is expressed by equations (2), (3) and (4).

[0013]

[Equation 1]

[0014]

[Equation 2]

[0015]

[Equation 3]

[0016]

[Equation 4] Here, in each of the above formulas (1) to (4), dp is the droplet diameter, μ
Is the viscosity of the gas, ρ _l is the droplet density, ρ _g is the gas density,
g is the acceleration of gravity, L is the latent heat of vaporization of the droplet, h _c is the film heat transfer coefficient, Tg is the temperature of the gas, T _l is the temperature of the droplet, C is a constant, and V ₀ is the gas velocity in the pipe. It is shown.

In these equations, as is clear from the equation (4), the flight distance (l) until the vaporization of the droplet is completed is proportional to the vaporization time (t) of the droplet and the gas flow velocity (V ₀ ). The longer the droplet evaporation time (t) and the faster the gas flow velocity (V ₀ ) are, the larger the droplet evaporation time (t) is, as is clear from the equation (3). The droplet diameter (dp) is related (ie, the smaller the droplet diameter, the shorter the evaporation time), and the flight distance (l) to the end of droplet evaporation is It can be seen that the two factors, namely the gas flow velocity (V ₀ ) and the droplet diameter (dp) are directly and largely dependent.

Further, as is clear from the equations (1), (3) and (4), the larger the droplet diameter is (that is, dp
₂ > dp ₁ ), the vertical terminal velocity of the droplet (Vz), the evaporation time (t) of the droplet, and the flight distance (l
₁₂ ) becomes large, and conversely, as the particle size of the droplet becomes smaller (that is, dp ₁ <dp ₂ ), the vertical terminal velocity (Vz) of the droplet, the evaporation time (t) of the droplet, and The flight distance (l ₁₁ ) until the end of evaporation of the droplet is reduced.

In the above-mentioned conventional odorizing method, especially when the gas flow velocity is high, the distance required for the odorizing liquid to evaporate reaches several tens of meters. In order to eliminate the above-mentioned inconvenience, etc., while various efforts have been made and studied from various directions, the above-mentioned relations, that is, the flight distance (l) until the end of vaporization of the liquid droplets is the gas flow velocity (V
₀ ) and the diameter (dp) of the droplet, and the like, and by using this to control the diameter of the droplet depending on the gas flow rate, evaporation can be performed without increasing the flight distance. The present invention has been completed by finding out that it is possible to end the process and also save energy.

[0020]

That is, the present invention is
In the method of odorizing city gas by adding odorant liquid to the city gas as droplets, the added droplets are further atomized (atomized) compared to the above-mentioned conventional method, and this particle size is used as the gas flow velocity. By controlling according to how to shorten the pipe length required for odor, atomization of the droplets (atomization)
And the evaporation can be controlled immediately and accurately, and at the same time, by optimally controlling the energy required for atomization,
It is an object of the present invention to provide a method for odorizing city gas that enables effective energy saving.

[0021]

SUMMARY OF THE INVENTION The present invention relates to a method for odorizing city gas by adding and evaporating the odorant to city gas, and an atomizing device is provided in the odorant adding portion of the gas pipe. Along with the provision of a odorant addition unit, a gas flow velocity measurement unit is installed to control the degree of atomization (atomization) of the odorant liquid depending on the gas flow velocity value obtained by this measurement unit. A method of odorizing a characteristic city gas is provided.

Here, as the atomizing device, an ultrasonic atomizing device, a pressure nozzle type (pressurizing liquid to spray it through pores), and a two-fluid nozzle type (liquid flowing out through pores, Atomizing nozzle type such as high-speed gas flowing to the periphery to atomize the liquid), disk atomizer type (liquid is supplied to the center of the disk rotating at high speed, and the liquid is atomized around the disk by centrifugal force Although various known types can be used, among them, from the viewpoint of not requiring separate rotation power and being easy to control the degree of miniaturization, ultrasonic waves are particularly preferable. Atomizers and pressurized nozzle type atomizers are preferred.

Further, according to the present invention, the droplets atomized by the atomizing device have a normal gas flow rate [for example, when the pipe pressure is 53 Kgf / cm ² , the gas flow rate is Although it fluctuates within a range of approximately 50 to 300 (t / h), the gas flow velocity is approximately 1.7 to 1 correspondingly.
Fluctuates in the range of 0.2 (m / s)], the above-mentioned conventional number 1
Finer than 00 μm with a diameter of several μm to several tens
The atomization is carried out to a particle size in the range of μm, and the degree of atomization in that range is set according to the gas flow rate. This particle size is controlled by, for example, a pressure nozzle type as the atomizing device. It can be implemented by controlling the degree of boosting by the pump.

As the odorant, dimethyl sulfide (H ₃ C--S--CH ₃ , DMS, boiling point = 37.3)
℃), tertiary-butyl mercaptan [C (CH ₃ ) ₃
-SH, TBM, boiling point = 63.7 to 64.7 ° C] and the like, and usually a mixture of both (DMS: TMB = 2:
Although it is used as 3), it is not limited to this in the present invention, and any liquid form can be applied.

[0025]

Embodiments of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to these embodiments. 1 is a schematic view showing one embodiment of the present invention.
The same parts as those in FIG. 2 are designated by the same reference numerals.

Reference numeral 1 denotes a gas pipe, and the arrow (→) indicates the direction of the gas flow in the pipe 1 as in the case of FIG. Denoted at 2 is an odorant tank, 3 is an odorant conduit, 4 is an odorant pump provided on the way, and the odorant conduit 3 is connected to an odorant supply pipe 6 through a valve 5. . As shown in the figure, the end of the odorant supply pipe 6 is installed in the gas pipe 1 in the form of a pressure nozzle, and the odorant is sprayed by the pressure nozzle 7 and added as fine droplets. Is configured. Although the odorant supply pipe 6, the nozzle 7 and the atomizing device 12 are shown separately in FIG. 1, the odorant supply pipe and the nozzle are also integrated when particularly atomizing and spraying in the nozzle form. It is desirable to configure it as an atomizing device.

A gas flow meter 9 measures the flow rate of the fuel gas passing through the gas pipe 1, and the gas flow rate value measured by the gas flow meter 9 is transmitted to the pump 4 through the signal line 10. The necessary amount (that is, an effective amount) of the odorizing liquid is added according to the flow rate, but in the present invention, the gas flow rate corresponding to the gas flow rate is calculated at the same time, and the atomization device 12 is controlled depending on the gas flow rate. This is for controlling the degree of atomization of the odorizing liquid for sessification, that is, the atomization diameter thereof.

In FIG. 1, a calculation unit for calculating the gas flow velocity corresponding to the gas flow rate is not shown, but this calculation is performed by a conventional method, for example, a micro computer connected to the signal line 10. The gas flow velocity value obtained here is transmitted from the microcomputer to the atomization device 12 via the signal line 11, for example, but the gas flow rate and the gas flow velocity are separately measured. When the gas composition and the diameter of the gas pipe are constant, there is a proportional relationship between the gas flow rate and the gas flow rate. Therefore, the gas based on the measurement value of the flow meter 9 is set based on the preset relationship between the two. It can be controlled by the flow rate.

Next, an example of the operation will be explained. When the gas flow velocity in the pipe 1 is high [state of FIG. 3 (a)], the flight distance to the end of evaporation of the droplets in the above-mentioned conventional method. Is longer [l ₁₂ in FIG. 3 (a)], but in this case, the atomizing device 12 according to the present invention atomizes the particle size to a smaller size and shortens the flight distance until the end of evaporation of the droplets []. Figure 3
In (a), l ₁₁ ].

On the other hand, when the gas flow velocity is low [Fig.
(State of (b)], the flight distance until the end of evaporation of the liquid droplets is shortened, so the degree of atomization by the atomizing device 12 is reduced [dp ₂ in FIG. 3 (b)]. As described above, according to the present invention, it is possible to sufficiently atomize and evaporate the odorant liquid without separately lengthening the pipe, avoid unnecessary atomization, and supply the energy required for atomization. It can be made smaller.

In this respect, in the above-mentioned conventional method, only the gas flow rate is used as a guideline to regulate the addition amount of the odorant, but according to the present invention, the diameter of the particles is about several μm to several tens of μm. By atomizing into a diameter, detecting the gas flow rate in addition to the gas flow rate, and controlling the degree of atomization of the odorant liquid, that is, the degree of atomization of the odorant by the atomizer 12 based on this gas flow rate value. The odorant can be effectively and accurately added, evaporated and controlled without separately lengthening the gas pipe for the odorizing part and without adding unnecessary energy.

[0032]

As described above, according to the present invention, in the method for odorizing city gas by adding and evaporating the odorizing liquid as droplets to the city gas, the odorizing liquid mist is separately added at the time of addition. By controlling the degree of atomization of the added odorant liquid by using a gasification device, the evaporation distance can be shortened compared to the conventional odorization method, and the pipe length of the odorization part can be lengthened. You can eliminate the need to do. Further, by controlling the atomizing diameter of the added odorous liquid depending on the gas flow rate, it is possible to eliminate unnecessary miniaturization of the droplets, thereby obtaining an effective energy saving effect.

[Brief description of drawings]

FIG. 1 is a schematic view showing an aspect of an odorizing method according to the present invention.

FIG. 2 is a diagram showing an aspect of a conventional odorizing method for fuel gas such as city gas.

FIG. 3 is a schematic diagram for explaining a relationship between an evaporation distance of an odorizing liquid and a gas flow velocity.

[Explanation of symbols]

 1 Gas pipe 2 Odor liquid tank 3 Odor liquid conduit 4 Odor liquid pump 5 Valve 6 Odor liquid supply pipe 7 Nozzle 8 Odor liquid droplet 9 Gas flow meter 10, 11 Signal line 12 Atomizer

Claims (3)

[Claims] 1. A method for odorizing city gas by adding and evaporating the odorizing solution into a city gas pipe, and an odorizing solution atomizer is provided at the addition part, and the gas flow velocity is measured upstream thereof. By providing the part, the degree of atomization of the odorizing liquid in the odorizing liquid atomizing device is controlled according to the gas flow velocity measured by the flow velocity measuring unit. 2. The method of odorizing city gas according to claim 1, wherein a pressure nozzle type atomizing device or an ultrasonic atomizing device is used as the odorizing liquid atomizing device. 3. The city according to claim 1 or 2, wherein the atomization degree of the odorizing liquid is controlled so that the diameter of the liquid droplet is from several μm to several tens of μm according to the gas flow velocity. Gas odor method.